From: Vineet Gupta <[email protected]>
Hi Greg,
Here's the updated revision with fixes per your review comments.
-Rebased off tty-next tip.
-Build tested for x86, both as builtin and as module
-Same driver (as module) verified on ARCAngel4 Board.
Please consider applying.
Thanks,
Vineet
v5:
* Driver now builds as module; default !y
* Fixed some build wreckage due to SERIAL_ARC && !SERIAL_ARC_CONSOLE
* Fixed a sparse warning due to forced cast, hence reg offsets now in bytes
v4:
* UAPI disintegration fallout for serial_core.h
* rebased off of tty-next
v3:
* Removed empty arc_serial_set_ldisc()
* More set_termios fixes - CSIZE forced to CS8 (for 8N1)
* global @running_on_iss replaced with platform data, saved in device
specific port structure.
v2:
* ttyARC used as device name
* Dynamic assignment of major/minor numbers.
* Ref counting tty in rx routine to prevent it from disappearing in
case of a hangup
* set_termios fixes:
- hardware flow control/parity are marked as unsupported
- baud written back to termios
* cosmetics such as commenting the need for @running_on_iss, empty lines
etc
Vineet Gupta (1):
serial/arc-uart: Add new driver
drivers/tty/serial/Kconfig | 23 ++
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/arc_uart.c | 754 ++++++++++++++++++++++++++++++++++++++
include/uapi/linux/serial_core.h | 2 +
4 files changed, 780 insertions(+), 0 deletions(-)
create mode 100644 drivers/tty/serial/arc_uart.c
--
1.7.4.1
From: Vineet Gupta <[email protected]>
Driver for non-standard on-chip UART, instantiated in the ARC (Synopsys)
FPGA Boards such as ARCAngel4/ML50x
Signed-off-by: Vineet Gupta <[email protected]>
---
drivers/tty/serial/Kconfig | 23 ++
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/arc_uart.c | 754 ++++++++++++++++++++++++++++++++++++++
include/uapi/linux/serial_core.h | 2 +
4 files changed, 780 insertions(+), 0 deletions(-)
create mode 100644 drivers/tty/serial/arc_uart.c
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 2a53be5..b176801 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1423,4 +1423,27 @@ config SERIAL_EFM32_UART_CONSOLE
depends on SERIAL_EFM32_UART=y
select SERIAL_CORE_CONSOLE
+config SERIAL_ARC
+ tristate "ARC UART driver support"
+ select SERIAL_CORE
+ help
+ Driver for on-chip UART for ARC(Synopsys) for the legacy
+ FPGA Boards (ML50x/ARCAngel4)
+
+config SERIAL_ARC_CONSOLE
+ bool "Console on ARC UART"
+ depends on SERIAL_ARC=y
+ select SERIAL_CORE_CONSOLE
+ help
+ Enable system Console on ARC UART
+
+config SERIAL_ARC_NR_PORTS
+ int "Number of ARC UART ports"
+ depends on SERIAL_ARC
+ range 1 3
+ default "1"
+ help
+ Set this to the number of serial ports you want the driver
+ to support.
+
endmenu
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 4f694da..df1b998 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -82,3 +82,4 @@ obj-$(CONFIG_SERIAL_XILINX_PS_UART) += xilinx_uartps.o
obj-$(CONFIG_SERIAL_SIRFSOC) += sirfsoc_uart.o
obj-$(CONFIG_SERIAL_AR933X) += ar933x_uart.o
obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
+obj-$(CONFIG_SERIAL_ARC) += arc_uart.o
diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
new file mode 100644
index 0000000..c12efae
--- /dev/null
+++ b/drivers/tty/serial/arc_uart.c
@@ -0,0 +1,754 @@
+/*
+ * ARC On-Chip(fpga) UART Driver
+ *
+ * Copyright (C) 2010-2012 Synopsys, Inc. (http://www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * vineetg: July 10th 2012
+ * -Decoupled the driver from arch/arc
+ * +Using platform_get_resource() for irq/membase (thx to bfin_uart.c)
+ * +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
+ *
+ * Vineetg: Aug 21st 2010
+ * -Is uart_tx_stopped() not done in tty write path as it has already been
+ * taken care of, in serial core
+ *
+ * Vineetg: Aug 18th 2010
+ * -New Serial Core based ARC UART driver
+ * -Derived largely from blackfin driver albiet with some major tweaks
+ *
+ * TODO:
+ * -check if sysreq works
+ */
+
+#if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/module.h>
+#include <linux/serial.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/platform_device.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_core.h>
+#include <linux/io.h>
+
+/*************************************
+ * ARC UART Hardware Specs
+ ************************************/
+#define ARC_UART_TX_FIFO_SIZE 1
+
+/*
+ * UART Register set (this is not a Standards Compliant IP)
+ * Also each reg is Word aligned, but only 8 bits wide
+ */
+#define R_ID0 0
+#define R_ID1 4
+#define R_ID2 8
+#define R_ID3 12
+#define R_DATA 16
+#define R_STS 20
+#define R_BAUDL 24
+#define R_BAUDH 28
+
+/* Bits for UART Status Reg (R/W) */
+#define RXIENB 0x04 /* Receive Interrupt Enable */
+#define TXIENB 0x40 /* Transmit Interrupt Enable */
+
+#define RXEMPTY 0x20 /* Receive FIFO Empty: No char receivede */
+#define TXEMPTY 0x80 /* Transmit FIFO Empty, thus char can be written into */
+
+#define RXFULL 0x08 /* Receive FIFO full */
+#define RXFULL1 0x10 /* Receive FIFO has space for 1 char (tot space=4) */
+
+#define RXFERR 0x01 /* Frame Error: Stop Bit not detected */
+#define RXOERR 0x02 /* OverFlow Err: Char recv but RXFULL still set */
+
+/* Uart bit fiddling helpers: lowest level */
+#define RBASE(uart, reg) (uart->port.membase + reg)
+#define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
+#define UART_REG_GET(u, r) readb(RBASE(u, r))
+
+#define UART_REG_OR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
+#define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
+
+/* Uart bit fiddling helpers: API level */
+#define UART_SET_DATA(uart, val) UART_REG_SET(uart, R_DATA, val)
+#define UART_GET_DATA(uart) UART_REG_GET(uart, R_DATA)
+
+#define UART_SET_BAUDH(uart, val) UART_REG_SET(uart, R_BAUDH, val)
+#define UART_SET_BAUDL(uart, val) UART_REG_SET(uart, R_BAUDL, val)
+
+#define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
+#define UART_GET_STATUS(uart) UART_REG_GET(uart, R_STS)
+
+#define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
+#define UART_RX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB)
+#define UART_TX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, TXIENB)
+
+#define UART_ALL_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
+#define UART_RX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB)
+#define UART_TX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, TXIENB)
+
+#define ARC_SERIAL_DEV_NAME "ttyARC"
+
+struct arc_uart_port {
+ struct uart_port port;
+ unsigned long baud;
+ int is_emulated; /* H/w vs. Instruction Set Simulator */
+};
+
+static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
+
+#ifdef CONFIG_SERIAL_ARC_CONSOLE
+static struct console arc_console;
+#endif
+
+#define DRIVER_NAME "arc-uart"
+
+static struct uart_driver arc_uart_driver = {
+ .owner = THIS_MODULE,
+ .driver_name = DRIVER_NAME,
+ .dev_name = ARC_SERIAL_DEV_NAME,
+ .major = 0,
+ .minor = 0,
+ .nr = CONFIG_SERIAL_ARC_NR_PORTS,
+#ifdef CONFIG_SERIAL_ARC_CONSOLE
+ .cons = &arc_console,
+#else
+ .cons = NULL,
+#endif
+};
+
+static void arc_serial_stop_rx(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+
+ UART_RX_IRQ_DISABLE(uart);
+}
+
+static void arc_serial_stop_tx(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+
+ while (!(UART_GET_STATUS(uart) & TXEMPTY))
+ cpu_relax();
+
+ UART_TX_IRQ_DISABLE(uart);
+}
+
+/*
+ * Return TIOCSER_TEMT when transmitter is not busy.
+ */
+static unsigned int arc_serial_tx_empty(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+ unsigned int stat;
+
+ stat = UART_GET_STATUS(uart);
+ if (stat & TXEMPTY)
+ return TIOCSER_TEMT;
+ else
+ return 0;
+}
+
+/*
+ * Driver internal routine, used by both tty(serial core) as well as tx-isr
+ * -Called under spinlock in either cases
+ * -also tty->stopped / tty->hw_stopped has already been checked
+ * = by uart_start( ) before calling us
+ * = tx_ist checks that too before calling
+ */
+static void arc_serial_tx_chars(struct arc_uart_port *uart)
+{
+ struct circ_buf *xmit = &uart->port.state->xmit;
+ int sent = 0;
+ unsigned char ch;
+
+ if (unlikely(uart->port.x_char)) {
+ UART_SET_DATA(uart, uart->port.x_char);
+ uart->port.icount.tx++;
+ uart->port.x_char = 0;
+ sent = 1;
+ } else if (xmit->tail != xmit->head) { /* TODO: uart_circ_empty */
+ ch = xmit->buf[xmit->tail];
+ xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+ uart->port.icount.tx++;
+ while (!(UART_GET_STATUS(uart) & TXEMPTY))
+ cpu_relax();
+ UART_SET_DATA(uart, ch);
+ sent = 1;
+ }
+
+ /*
+ * If num chars in xmit buffer are too few, ask tty layer for more.
+ * By Hard ISR to schedule processing in software interrupt part
+ */
+ if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+ uart_write_wakeup(&uart->port);
+
+ if (sent)
+ UART_TX_IRQ_ENABLE(uart);
+}
+
+/*
+ * port is locked and interrupts are disabled
+ * uart_start( ) calls us under the port spinlock irqsave
+ */
+static void arc_serial_start_tx(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+
+ arc_serial_tx_chars(uart);
+}
+
+static void arc_serial_rx_chars(struct arc_uart_port *uart)
+{
+ struct tty_struct *tty = tty_port_tty_get(&uart->port.state->port);
+ unsigned int status, ch, flg = 0;
+
+ if (!tty)
+ return;
+
+ /*
+ * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
+ * is very subtle. Here's how ...
+ * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
+ * driver reads the DATA Reg and keeps doing that in a loop, until
+ * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
+ * before RX-EMPTY=0, implies some sort of buffering going on in the
+ * controller, which is indeed the Rx-FIFO.
+ */
+ while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
+
+ ch = UART_GET_DATA(uart);
+ uart->port.icount.rx++;
+
+ if (unlikely(status & (RXOERR | RXFERR))) {
+ if (status & RXOERR) {
+ uart->port.icount.overrun++;
+ flg = TTY_OVERRUN;
+ UART_CLR_STATUS(uart, RXOERR);
+ }
+
+ if (status & RXFERR) {
+ uart->port.icount.frame++;
+ flg = TTY_FRAME;
+ UART_CLR_STATUS(uart, RXFERR);
+ }
+ } else
+ flg = TTY_NORMAL;
+
+ if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
+ goto done;
+
+ uart_insert_char(&uart->port, status, RXOERR, ch, flg);
+
+done:
+ tty_flip_buffer_push(tty);
+ }
+
+ tty_kref_put(tty);
+}
+
+/*
+ * A note on the Interrupt handling state machine of this driver
+ *
+ * kernel printk writes funnel thru the console driver framework and in order
+ * to keep things simple as well as efficient, it writes to UART in polled
+ * mode, in one shot, and exits.
+ *
+ * OTOH, Userland output (via tty layer), uses interrupt based writes as there
+ * can be undeterministic delay between char writes.
+ *
+ * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
+ * disabled.
+ *
+ * When tty has some data to send out, serial core calls driver's start_tx
+ * which
+ * -checks-if-tty-buffer-has-char-to-send
+ * -writes-data-to-uart
+ * -enable-tx-intr
+ *
+ * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
+ * The first thing Tx ISR does is disable further Tx interrupts (as this could
+ * be the last char to send, before settling down into the quiet polled mode).
+ * It then calls the exact routine used by tty layer write to send out any
+ * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
+ * of no data, it remains disabled.
+ * This is how the transmit state machine is dynamically switched on/off
+ */
+
+static irqreturn_t arc_serial_isr(int irq, void *dev_id)
+{
+ struct arc_uart_port *uart = dev_id;
+ unsigned int status;
+
+ status = UART_GET_STATUS(uart);
+
+ /*
+ * Single IRQ for both Rx (data available) Tx (room available) Interrupt
+ * notifications from the UART Controller.
+ * To demultiplex between the two, we check the relevant bits
+ */
+ if ((status & RXIENB) && !(status & RXEMPTY)) {
+
+ /* already in ISR, no need of xx_irqsave */
+ spin_lock(&uart->port.lock);
+ arc_serial_rx_chars(uart);
+ spin_unlock(&uart->port.lock);
+ }
+
+ if ((status & TXIENB) && (status & TXEMPTY)) {
+
+ /* Unconditionally disable further Tx-Interrupts.
+ * will be enabled by tx_chars() if needed.
+ */
+ UART_TX_IRQ_DISABLE(uart);
+
+ spin_lock(&uart->port.lock);
+
+ if (!uart_tx_stopped(&uart->port))
+ arc_serial_tx_chars(uart);
+
+ spin_unlock(&uart->port.lock);
+ }
+
+ return IRQ_HANDLED;
+}
+
+static unsigned int arc_serial_get_mctrl(struct uart_port *port)
+{
+ /*
+ * Pretend we have a Modem status reg and following bits are
+ * always set, to satify the serial core state machine
+ * (DSR) Data Set Ready
+ * (CTS) Clear To Send
+ * (CAR) Carrier Detect
+ */
+ return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+}
+
+static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+ /* MCR not present */
+}
+
+/* Enable Modem Status Interrupts */
+
+static void arc_serial_enable_ms(struct uart_port *port)
+{
+ /* MSR not present */
+}
+
+static void arc_serial_break_ctl(struct uart_port *port, int break_state)
+{
+ /* ARC UART doesn't support sending Break signal */
+}
+
+static int arc_serial_startup(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+
+ /* Before we hook up the ISR, Disable all UART Interrupts */
+ UART_ALL_IRQ_DISABLE(uart);
+
+ if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
+ uart)) {
+ pr_warn("Unable to attach ARC UART interrupt\n");
+ return -EBUSY;
+ }
+
+ UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
+
+ return 0;
+}
+
+/* This is not really needed */
+static void arc_serial_shutdown(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+ free_irq(uart->port.irq, uart);
+}
+
+static void
+arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
+ struct ktermios *old)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+ unsigned int baud, uartl, uarth, hw_val;
+ unsigned long flags;
+
+ /*
+ * Use the generic handler so that any specially encoded baud rates
+ * such as SPD_xx flags or "%B0" can be handled
+ * Max Baud I suppose will not be more than current 115K * 4
+ * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
+ * spread over two 8-bit registers
+ */
+ baud = uart_get_baud_rate(port, new, old, 0, 460800);
+
+ hw_val = port->uartclk / (uart->baud * 4) - 1;
+ uartl = hw_val & 0xFF;
+ uarth = (hw_val >> 8) & 0xFF;
+
+ /*
+ * UART ISS(Instruction Set simulator) emulation has a subtle bug:
+ * A existing value of Baudh = 0 is used as a indication to startup
+ * it's internal state machine.
+ * Thus if baudh is set to 0, 2 times, it chokes.
+ * This happens with BAUD=115200 and the formaula above
+ * Until that is fixed, when running on ISS, we will set baudh to !0
+ */
+ if (uart->is_emulated)
+ uarth = 1;
+
+ spin_lock_irqsave(&port->lock, flags);
+
+ UART_ALL_IRQ_DISABLE(uart);
+
+ UART_SET_BAUDL(uart, uartl);
+ UART_SET_BAUDH(uart, uarth);
+
+ UART_RX_IRQ_ENABLE(uart);
+
+ /*
+ * UART doesn't support Parity/Hardware Flow Control;
+ * Only supports 8N1 character size
+ */
+ new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
+ new->c_cflag |= CS8;
+
+ if (old)
+ tty_termios_copy_hw(new, old);
+
+ /* Don't rewrite B0 */
+ if (tty_termios_baud_rate(new))
+ tty_termios_encode_baud_rate(new, baud, baud);
+
+ uart_update_timeout(port, new->c_cflag, baud);
+
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *arc_serial_type(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+
+ return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
+}
+
+/*
+ * Release the memory region(s) being used by 'port'.
+ */
+static void arc_serial_release_port(struct uart_port *port)
+{
+}
+
+/*
+ * Request the memory region(s) being used by 'port'.
+ */
+static int arc_serial_request_port(struct uart_port *port)
+{
+ return 0;
+}
+
+/*
+ * Verify the new serial_struct (for TIOCSSERIAL).
+ */
+static int
+arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+ return 0;
+}
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void arc_serial_config_port(struct uart_port *port, int flags)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+
+ if (flags & UART_CONFIG_TYPE &&
+ arc_serial_request_port(&uart->port) == 0)
+ uart->port.type = PORT_ARC;
+}
+
+#if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
+
+static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+
+ while (!(UART_GET_STATUS(uart) & TXEMPTY))
+ cpu_relax();
+
+ UART_SET_DATA(uart, chr);
+}
+#endif
+
+#ifdef CONFIG_CONSOLE_POLL
+static int arc_serial_poll_getchar(struct uart_port *port)
+{
+ struct arc_uart_port *uart = (struct arc_uart_port *)port;
+ unsigned char chr;
+
+ while (!(UART_GET_STATUS(uart) & RXEMPTY))
+ cpu_relax();
+
+ chr = UART_GET_DATA(uart);
+ return chr;
+}
+#endif
+
+static struct uart_ops arc_serial_pops = {
+ .tx_empty = arc_serial_tx_empty,
+ .set_mctrl = arc_serial_set_mctrl,
+ .get_mctrl = arc_serial_get_mctrl,
+ .stop_tx = arc_serial_stop_tx,
+ .start_tx = arc_serial_start_tx,
+ .stop_rx = arc_serial_stop_rx,
+ .enable_ms = arc_serial_enable_ms,
+ .break_ctl = arc_serial_break_ctl,
+ .startup = arc_serial_startup,
+ .shutdown = arc_serial_shutdown,
+ .set_termios = arc_serial_set_termios,
+ .type = arc_serial_type,
+ .release_port = arc_serial_release_port,
+ .request_port = arc_serial_request_port,
+ .config_port = arc_serial_config_port,
+ .verify_port = arc_serial_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+ .poll_put_char = arc_serial_poll_putchar,
+ .poll_get_char = arc_serial_poll_getchar,
+#endif
+};
+
+static int __devinit
+arc_uart_init_one(struct platform_device *pdev, struct arc_uart_port *uart)
+{
+ struct resource *res, *res2;
+ unsigned long *plat_data;
+
+ if (pdev->id < 0 || pdev->id >= CONFIG_SERIAL_ARC_NR_PORTS) {
+ dev_err(&pdev->dev, "Wrong uart platform device id.\n");
+ return -ENOENT;
+ }
+
+ plat_data = ((unsigned long *)(pdev->dev.platform_data));
+ uart->baud = plat_data[0];
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+ if (!res2)
+ return -ENODEV;
+
+ uart->port.mapbase = res->start;
+ uart->port.membase = ioremap_nocache(res->start, resource_size(res));
+ if (!uart->port.membase)
+ /* No point of pr_err since UART itself is hosed here */
+ return -ENXIO;
+
+ uart->port.irq = res2->start;
+ uart->port.dev = &pdev->dev;
+ uart->port.iotype = UPIO_MEM;
+ uart->port.flags = UPF_BOOT_AUTOCONF;
+ uart->port.line = pdev->id;
+ uart->port.ops = &arc_serial_pops;
+
+ uart->port.uartclk = plat_data[1];
+ uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
+
+ /*
+ * uart_insert_char( ) uses it in decideding whether to ignore a
+ * char or not. Explicitly setting it here, removes the subtelty
+ */
+ uart->port.ignore_status_mask = 0;
+
+ /* Real Hardware vs. emulated to work around a bug */
+ uart->is_emulated = !!plat_data[2];
+
+ return 0;
+}
+
+#ifdef CONFIG_SERIAL_ARC_CONSOLE
+
+static int __devinit arc_serial_console_setup(struct console *co, char *options)
+{
+ struct uart_port *port;
+ int baud = 115200;
+ int bits = 8;
+ int parity = 'n';
+ int flow = 'n';
+
+ if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
+ return -ENODEV;
+
+ /*
+ * The uart port backing the console (e.g. ttyARC1) might not have been
+ * init yet. If so, defer the console setup to after the port.
+ */
+ port = &arc_uart_ports[co->index].port;
+ if (!port->membase)
+ return -ENODEV;
+
+ if (options)
+ uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+ /*
+ * Serial core will call port->ops->set_termios( )
+ * which will set the baud reg
+ */
+ return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static void arc_serial_console_putchar(struct uart_port *port, int ch)
+{
+ arc_serial_poll_putchar(port, (unsigned char)ch);
+}
+
+/*
+ * Interrupts are disabled on entering
+ */
+static void arc_serial_console_write(struct console *co, const char *s,
+ unsigned int count)
+{
+ struct uart_port *port = &arc_uart_ports[co->index].port;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ uart_console_write(port, s, count, arc_serial_console_putchar);
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static struct console arc_console = {
+ .name = ARC_SERIAL_DEV_NAME,
+ .write = arc_serial_console_write,
+ .device = uart_console_device,
+ .setup = arc_serial_console_setup,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+ .data = &arc_uart_driver
+};
+
+static __init void early_serial_write(struct console *con, const char *s,
+ unsigned int n)
+{
+ struct uart_port *port = &arc_uart_ports[con->index].port;
+ unsigned int i;
+
+ for (i = 0; i < n; i++, s++) {
+ if (*s == '\n')
+ arc_serial_poll_putchar(port, '\r');
+ arc_serial_poll_putchar(port, *s);
+ }
+}
+
+static struct __initdata console arc_early_serial_console = {
+ .name = "early_ARCuart",
+ .write = early_serial_write,
+ .flags = CON_PRINTBUFFER | CON_BOOT,
+ .index = -1
+};
+
+static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
+{
+ arc_early_serial_console.index = pdev->id;
+
+ arc_uart_init_one(pdev, &arc_uart_ports[pdev->id]);
+
+ arc_serial_console_setup(&arc_early_serial_console, NULL);
+
+ register_console(&arc_early_serial_console);
+ return 0;
+}
+#else
+static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
+{
+ return -ENODEV;
+}
+#endif /* CONFIG_SERIAL_ARC_CONSOLE */
+
+static int __devinit arc_serial_probe(struct platform_device *pdev)
+{
+ struct arc_uart_port *uart;
+ int rc;
+
+ if (is_early_platform_device(pdev))
+ return arc_serial_probe_earlyprintk(pdev);
+
+ uart = &arc_uart_ports[pdev->id];
+ rc = arc_uart_init_one(pdev, uart);
+ if (rc)
+ return rc;
+
+ return uart_add_one_port(&arc_uart_driver, &uart->port);
+}
+
+static int __devexit arc_serial_remove(struct platform_device *pdev)
+{
+ /* This will never be called */
+ return 0;
+}
+
+static struct platform_driver arc_platform_driver = {
+ .probe = arc_serial_probe,
+ .remove = __devexit_p(arc_serial_remove),
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+#ifdef CONFIG_SERIAL_ARC_CONSOLE
+/*
+ * Register an early platform driver of "earlyprintk" class.
+ * ARCH platform code installs the driver and probes the early devices
+ * The installation could rely on user specifying earlyprintk=xyx in cmd line
+ * or it could be done independently, for all "earlyprintk" class drivers.
+ * [see arch/arc/plat-arcfpga/platform.c]
+ */
+early_platform_init("earlyprintk", &arc_platform_driver);
+
+#endif /* CONFIG_SERIAL_ARC_CONSOLE */
+
+static int __init arc_serial_init(void)
+{
+ int ret;
+
+ pr_info("Serial: ARC serial driver: platform register\n");
+
+ ret = uart_register_driver(&arc_uart_driver);
+ if (ret)
+ return ret;
+
+ ret = platform_driver_register(&arc_platform_driver);
+ if (ret) {
+ pr_debug("uart register failed\n");
+ uart_unregister_driver(&arc_uart_driver);
+ }
+
+ return ret;
+}
+
+static void __exit arc_serial_exit(void)
+{
+ platform_driver_unregister(&arc_platform_driver);
+ uart_unregister_driver(&arc_uart_driver);
+}
+
+module_init(arc_serial_init);
+module_exit(arc_serial_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("plat-arcfpga/uart");
+MODULE_AUTHOR("Vineet Gupta");
+MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 7e1ab20..ebcc73f 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -215,5 +215,7 @@
/* Energy Micro efm32 SoC */
#define PORT_EFMUART 100
+/* ARC (Synopsys) on-chip UART */
+#define PORT_ARC 101
#endif /* _UAPILINUX_SERIAL_CORE_H */
--
1.7.4.1
On Fri, Oct 26, 2012 at 05:33:16PM +0530, [email protected] wrote:
> From: Vineet Gupta <[email protected]>
>
> Driver for non-standard on-chip UART, instantiated in the ARC (Synopsys)
> FPGA Boards such as ARCAngel4/ML50x
>
> Signed-off-by: Vineet Gupta <[email protected]>
> ---
> drivers/tty/serial/Kconfig | 23 ++
> drivers/tty/serial/Makefile | 1 +
> drivers/tty/serial/arc_uart.c | 754 ++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/serial_core.h | 2 +
> 4 files changed, 780 insertions(+), 0 deletions(-)
> create mode 100644 drivers/tty/serial/arc_uart.c
>
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 2a53be5..b176801 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -1423,4 +1423,27 @@ config SERIAL_EFM32_UART_CONSOLE
> depends on SERIAL_EFM32_UART=y
> select SERIAL_CORE_CONSOLE
>
> +config SERIAL_ARC
> + tristate "ARC UART driver support"
> + select SERIAL_CORE
> + help
> + Driver for on-chip UART for ARC(Synopsys) for the legacy
> + FPGA Boards (ML50x/ARCAngel4)
> +
> +config SERIAL_ARC_CONSOLE
> + bool "Console on ARC UART"
> + depends on SERIAL_ARC=y
> + select SERIAL_CORE_CONSOLE
> + help
> + Enable system Console on ARC UART
> +
> +config SERIAL_ARC_NR_PORTS
> + int "Number of ARC UART ports"
> + depends on SERIAL_ARC
> + range 1 3
> + default "1"
> + help
> + Set this to the number of serial ports you want the driver
> + to support.
> +
> endmenu
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index 4f694da..df1b998 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -82,3 +82,4 @@ obj-$(CONFIG_SERIAL_XILINX_PS_UART) += xilinx_uartps.o
> obj-$(CONFIG_SERIAL_SIRFSOC) += sirfsoc_uart.o
> obj-$(CONFIG_SERIAL_AR933X) += ar933x_uart.o
> obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
> +obj-$(CONFIG_SERIAL_ARC) += arc_uart.o
> diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
> new file mode 100644
> index 0000000..c12efae
> --- /dev/null
> +++ b/drivers/tty/serial/arc_uart.c
> @@ -0,0 +1,754 @@
> +/*
> + * ARC On-Chip(fpga) UART Driver
> + *
> + * Copyright (C) 2010-2012 Synopsys, Inc. (http://www.synopsys.com)
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * vineetg: July 10th 2012
> + * -Decoupled the driver from arch/arc
> + * +Using platform_get_resource() for irq/membase (thx to bfin_uart.c)
> + * +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
> + *
> + * Vineetg: Aug 21st 2010
> + * -Is uart_tx_stopped() not done in tty write path as it has already been
> + * taken care of, in serial core
> + *
> + * Vineetg: Aug 18th 2010
> + * -New Serial Core based ARC UART driver
> + * -Derived largely from blackfin driver albiet with some major tweaks
> + *
> + * TODO:
> + * -check if sysreq works
> + */
> +
> +#if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
> +#define SUPPORT_SYSRQ
> +#endif
> +
> +#include <linux/module.h>
> +#include <linux/serial.h>
> +#include <linux/console.h>
> +#include <linux/sysrq.h>
> +#include <linux/platform_device.h>
> +#include <linux/tty.h>
> +#include <linux/tty_flip.h>
> +#include <linux/serial_core.h>
> +#include <linux/io.h>
> +
> +/*************************************
> + * ARC UART Hardware Specs
> + ************************************/
> +#define ARC_UART_TX_FIFO_SIZE 1
> +
> +/*
> + * UART Register set (this is not a Standards Compliant IP)
> + * Also each reg is Word aligned, but only 8 bits wide
> + */
> +#define R_ID0 0
> +#define R_ID1 4
> +#define R_ID2 8
> +#define R_ID3 12
> +#define R_DATA 16
> +#define R_STS 20
> +#define R_BAUDL 24
> +#define R_BAUDH 28
> +
> +/* Bits for UART Status Reg (R/W) */
> +#define RXIENB 0x04 /* Receive Interrupt Enable */
> +#define TXIENB 0x40 /* Transmit Interrupt Enable */
> +
> +#define RXEMPTY 0x20 /* Receive FIFO Empty: No char receivede */
> +#define TXEMPTY 0x80 /* Transmit FIFO Empty, thus char can be written into */
> +
> +#define RXFULL 0x08 /* Receive FIFO full */
> +#define RXFULL1 0x10 /* Receive FIFO has space for 1 char (tot space=4) */
> +
> +#define RXFERR 0x01 /* Frame Error: Stop Bit not detected */
> +#define RXOERR 0x02 /* OverFlow Err: Char recv but RXFULL still set */
> +
> +/* Uart bit fiddling helpers: lowest level */
> +#define RBASE(uart, reg) (uart->port.membase + reg)
> +#define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
> +#define UART_REG_GET(u, r) readb(RBASE(u, r))
> +
> +#define UART_REG_OR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
> +#define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
> +
> +/* Uart bit fiddling helpers: API level */
> +#define UART_SET_DATA(uart, val) UART_REG_SET(uart, R_DATA, val)
> +#define UART_GET_DATA(uart) UART_REG_GET(uart, R_DATA)
> +
> +#define UART_SET_BAUDH(uart, val) UART_REG_SET(uart, R_BAUDH, val)
> +#define UART_SET_BAUDL(uart, val) UART_REG_SET(uart, R_BAUDL, val)
> +
> +#define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
> +#define UART_GET_STATUS(uart) UART_REG_GET(uart, R_STS)
> +
> +#define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
> +#define UART_RX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB)
> +#define UART_TX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, TXIENB)
> +
> +#define UART_ALL_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
> +#define UART_RX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB)
> +#define UART_TX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, TXIENB)
> +
> +#define ARC_SERIAL_DEV_NAME "ttyARC"
> +
> +struct arc_uart_port {
> + struct uart_port port;
> + unsigned long baud;
> + int is_emulated; /* H/w vs. Instruction Set Simulator */
> +};
> +
> +static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
> +
> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
> +static struct console arc_console;
> +#endif
> +
> +#define DRIVER_NAME "arc-uart"
> +
> +static struct uart_driver arc_uart_driver = {
> + .owner = THIS_MODULE,
> + .driver_name = DRIVER_NAME,
> + .dev_name = ARC_SERIAL_DEV_NAME,
> + .major = 0,
> + .minor = 0,
> + .nr = CONFIG_SERIAL_ARC_NR_PORTS,
> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
> + .cons = &arc_console,
> +#else
> + .cons = NULL,
else branch isn't necessary. The structure is declared static and
everything is initialized to zero unless overwritten by code.
> +#endif
> +};
> +
> +static void arc_serial_stop_rx(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
I would suggest using container_of() here. It's very unlikely to happen,
but if another field is added before struct uart_port member in your
structure, this will break.
> + UART_RX_IRQ_DISABLE(uart);
> +}
> +
> +static void arc_serial_stop_tx(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> +
> + while (!(UART_GET_STATUS(uart) & TXEMPTY))
> + cpu_relax();
> +
> + UART_TX_IRQ_DISABLE(uart);
> +}
> +
> +/*
> + * Return TIOCSER_TEMT when transmitter is not busy.
> + */
> +static unsigned int arc_serial_tx_empty(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> + unsigned int stat;
> +
> + stat = UART_GET_STATUS(uart);
> + if (stat & TXEMPTY)
> + return TIOCSER_TEMT;
> + else
> + return 0;
else is unnecessary you can convert this into:
if (stat & TXEMPTY)
return TIOCSER_TEMT;
return 0;
> +}
> +
> +/*
> + * Driver internal routine, used by both tty(serial core) as well as tx-isr
> + * -Called under spinlock in either cases
> + * -also tty->stopped / tty->hw_stopped has already been checked
> + * = by uart_start( ) before calling us
> + * = tx_ist checks that too before calling
> + */
> +static void arc_serial_tx_chars(struct arc_uart_port *uart)
> +{
> + struct circ_buf *xmit = &uart->port.state->xmit;
> + int sent = 0;
> + unsigned char ch;
> +
> + if (unlikely(uart->port.x_char)) {
> + UART_SET_DATA(uart, uart->port.x_char);
> + uart->port.icount.tx++;
> + uart->port.x_char = 0;
> + sent = 1;
> + } else if (xmit->tail != xmit->head) { /* TODO: uart_circ_empty */
> + ch = xmit->buf[xmit->tail];
> + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> + uart->port.icount.tx++;
> + while (!(UART_GET_STATUS(uart) & TXEMPTY))
> + cpu_relax();
> + UART_SET_DATA(uart, ch);
> + sent = 1;
> + }
> +
> + /*
> + * If num chars in xmit buffer are too few, ask tty layer for more.
> + * By Hard ISR to schedule processing in software interrupt part
> + */
> + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> + uart_write_wakeup(&uart->port);
> +
> + if (sent)
> + UART_TX_IRQ_ENABLE(uart);
> +}
> +
> +/*
> + * port is locked and interrupts are disabled
> + * uart_start( ) calls us under the port spinlock irqsave
> + */
> +static void arc_serial_start_tx(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> +
> + arc_serial_tx_chars(uart);
> +}
> +
> +static void arc_serial_rx_chars(struct arc_uart_port *uart)
> +{
> + struct tty_struct *tty = tty_port_tty_get(&uart->port.state->port);
> + unsigned int status, ch, flg = 0;
> +
> + if (!tty)
> + return;
can this really happen ? why would you receive characters while tty is
NULL ?
> + /*
> + * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
> + * is very subtle. Here's how ...
> + * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
> + * driver reads the DATA Reg and keeps doing that in a loop, until
> + * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
> + * before RX-EMPTY=0, implies some sort of buffering going on in the
> + * controller, which is indeed the Rx-FIFO.
> + */
> + while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
> +
> + ch = UART_GET_DATA(uart);
> + uart->port.icount.rx++;
> +
> + if (unlikely(status & (RXOERR | RXFERR))) {
> + if (status & RXOERR) {
> + uart->port.icount.overrun++;
> + flg = TTY_OVERRUN;
> + UART_CLR_STATUS(uart, RXOERR);
> + }
> +
> + if (status & RXFERR) {
> + uart->port.icount.frame++;
> + flg = TTY_FRAME;
> + UART_CLR_STATUS(uart, RXFERR);
> + }
> + } else
> + flg = TTY_NORMAL;
> +
> + if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
> + goto done;
> +
> + uart_insert_char(&uart->port, status, RXOERR, ch, flg);
> +
> +done:
> + tty_flip_buffer_push(tty);
> + }
> +
> + tty_kref_put(tty);
> +}
> +
> +/*
> + * A note on the Interrupt handling state machine of this driver
> + *
> + * kernel printk writes funnel thru the console driver framework and in order
> + * to keep things simple as well as efficient, it writes to UART in polled
> + * mode, in one shot, and exits.
> + *
> + * OTOH, Userland output (via tty layer), uses interrupt based writes as there
> + * can be undeterministic delay between char writes.
> + *
> + * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
> + * disabled.
> + *
> + * When tty has some data to send out, serial core calls driver's start_tx
> + * which
> + * -checks-if-tty-buffer-has-char-to-send
> + * -writes-data-to-uart
> + * -enable-tx-intr
> + *
> + * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
> + * The first thing Tx ISR does is disable further Tx interrupts (as this could
> + * be the last char to send, before settling down into the quiet polled mode).
> + * It then calls the exact routine used by tty layer write to send out any
> + * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
> + * of no data, it remains disabled.
> + * This is how the transmit state machine is dynamically switched on/off
> + */
> +
> +static irqreturn_t arc_serial_isr(int irq, void *dev_id)
> +{
> + struct arc_uart_port *uart = dev_id;
> + unsigned int status;
> +
> + status = UART_GET_STATUS(uart);
> +
> + /*
> + * Single IRQ for both Rx (data available) Tx (room available) Interrupt
> + * notifications from the UART Controller.
> + * To demultiplex between the two, we check the relevant bits
> + */
> + if ((status & RXIENB) && !(status & RXEMPTY)) {
> +
> + /* already in ISR, no need of xx_irqsave */
> + spin_lock(&uart->port.lock);
> + arc_serial_rx_chars(uart);
> + spin_unlock(&uart->port.lock);
> + }
> +
> + if ((status & TXIENB) && (status & TXEMPTY)) {
> +
> + /* Unconditionally disable further Tx-Interrupts.
> + * will be enabled by tx_chars() if needed.
> + */
> + UART_TX_IRQ_DISABLE(uart);
> +
> + spin_lock(&uart->port.lock);
> +
> + if (!uart_tx_stopped(&uart->port))
> + arc_serial_tx_chars(uart);
> +
> + spin_unlock(&uart->port.lock);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static unsigned int arc_serial_get_mctrl(struct uart_port *port)
> +{
> + /*
> + * Pretend we have a Modem status reg and following bits are
> + * always set, to satify the serial core state machine
> + * (DSR) Data Set Ready
> + * (CTS) Clear To Send
> + * (CAR) Carrier Detect
> + */
> + return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
> +}
> +
> +static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
> +{
> + /* MCR not present */
> +}
> +
> +/* Enable Modem Status Interrupts */
> +
> +static void arc_serial_enable_ms(struct uart_port *port)
> +{
> + /* MSR not present */
> +}
> +
> +static void arc_serial_break_ctl(struct uart_port *port, int break_state)
> +{
> + /* ARC UART doesn't support sending Break signal */
> +}
> +
> +static int arc_serial_startup(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> +
> + /* Before we hook up the ISR, Disable all UART Interrupts */
> + UART_ALL_IRQ_DISABLE(uart);
> +
> + if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
> + uart)) {
> + pr_warn("Unable to attach ARC UART interrupt\n");
> + return -EBUSY;
> + }
> +
> + UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
> +
> + return 0;
> +}
> +
> +/* This is not really needed */
> +static void arc_serial_shutdown(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> + free_irq(uart->port.irq, uart);
> +}
> +
> +static void
> +arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
> + struct ktermios *old)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> + unsigned int baud, uartl, uarth, hw_val;
> + unsigned long flags;
> +
> + /*
> + * Use the generic handler so that any specially encoded baud rates
> + * such as SPD_xx flags or "%B0" can be handled
> + * Max Baud I suppose will not be more than current 115K * 4
> + * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
> + * spread over two 8-bit registers
> + */
> + baud = uart_get_baud_rate(port, new, old, 0, 460800);
> +
> + hw_val = port->uartclk / (uart->baud * 4) - 1;
> + uartl = hw_val & 0xFF;
> + uarth = (hw_val >> 8) & 0xFF;
> +
> + /*
> + * UART ISS(Instruction Set simulator) emulation has a subtle bug:
> + * A existing value of Baudh = 0 is used as a indication to startup
> + * it's internal state machine.
> + * Thus if baudh is set to 0, 2 times, it chokes.
> + * This happens with BAUD=115200 and the formaula above
> + * Until that is fixed, when running on ISS, we will set baudh to !0
> + */
> + if (uart->is_emulated)
> + uarth = 1;
> +
> + spin_lock_irqsave(&port->lock, flags);
> +
> + UART_ALL_IRQ_DISABLE(uart);
> +
> + UART_SET_BAUDL(uart, uartl);
> + UART_SET_BAUDH(uart, uarth);
> +
> + UART_RX_IRQ_ENABLE(uart);
> +
> + /*
> + * UART doesn't support Parity/Hardware Flow Control;
> + * Only supports 8N1 character size
> + */
> + new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
> + new->c_cflag |= CS8;
> +
> + if (old)
> + tty_termios_copy_hw(new, old);
> +
> + /* Don't rewrite B0 */
> + if (tty_termios_baud_rate(new))
> + tty_termios_encode_baud_rate(new, baud, baud);
> +
> + uart_update_timeout(port, new->c_cflag, baud);
> +
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +static const char *arc_serial_type(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> +
> + return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
> +}
> +
> +/*
> + * Release the memory region(s) being used by 'port'.
> + */
> +static void arc_serial_release_port(struct uart_port *port)
> +{
> +}
> +
> +/*
> + * Request the memory region(s) being used by 'port'.
> + */
> +static int arc_serial_request_port(struct uart_port *port)
> +{
> + return 0;
> +}
> +
> +/*
> + * Verify the new serial_struct (for TIOCSSERIAL).
> + */
> +static int
> +arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
> +{
> + return 0;
> +}
why all these empty functions with wrong comments above them ??
> +/*
> + * Configure/autoconfigure the port.
> + */
> +static void arc_serial_config_port(struct uart_port *port, int flags)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> +
> + if (flags & UART_CONFIG_TYPE &&
> + arc_serial_request_port(&uart->port) == 0)
> + uart->port.type = PORT_ARC;
> +}
> +
> +#if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
> +
> +static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> +
> + while (!(UART_GET_STATUS(uart) & TXEMPTY))
> + cpu_relax();
> +
> + UART_SET_DATA(uart, chr);
> +}
> +#endif
> +
> +#ifdef CONFIG_CONSOLE_POLL
> +static int arc_serial_poll_getchar(struct uart_port *port)
> +{
> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> + unsigned char chr;
> +
> + while (!(UART_GET_STATUS(uart) & RXEMPTY))
> + cpu_relax();
> +
> + chr = UART_GET_DATA(uart);
> + return chr;
> +}
> +#endif
> +
> +static struct uart_ops arc_serial_pops = {
> + .tx_empty = arc_serial_tx_empty,
> + .set_mctrl = arc_serial_set_mctrl,
> + .get_mctrl = arc_serial_get_mctrl,
> + .stop_tx = arc_serial_stop_tx,
> + .start_tx = arc_serial_start_tx,
> + .stop_rx = arc_serial_stop_rx,
> + .enable_ms = arc_serial_enable_ms,
> + .break_ctl = arc_serial_break_ctl,
> + .startup = arc_serial_startup,
> + .shutdown = arc_serial_shutdown,
> + .set_termios = arc_serial_set_termios,
> + .type = arc_serial_type,
> + .release_port = arc_serial_release_port,
> + .request_port = arc_serial_request_port,
> + .config_port = arc_serial_config_port,
> + .verify_port = arc_serial_verify_port,
> +#ifdef CONFIG_CONSOLE_POLL
> + .poll_put_char = arc_serial_poll_putchar,
> + .poll_get_char = arc_serial_poll_getchar,
> +#endif
> +};
> +
> +static int __devinit
> +arc_uart_init_one(struct platform_device *pdev, struct arc_uart_port *uart)
> +{
> + struct resource *res, *res2;
> + unsigned long *plat_data;
> +
> + if (pdev->id < 0 || pdev->id >= CONFIG_SERIAL_ARC_NR_PORTS) {
> + dev_err(&pdev->dev, "Wrong uart platform device id.\n");
> + return -ENOENT;
> + }
> +
> + plat_data = ((unsigned long *)(pdev->dev.platform_data));
> + uart->baud = plat_data[0];
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return -ENODEV;
> +
> + res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> + if (!res2)
> + return -ENODEV;
> +
> + uart->port.mapbase = res->start;
> + uart->port.membase = ioremap_nocache(res->start, resource_size(res));
> + if (!uart->port.membase)
> + /* No point of pr_err since UART itself is hosed here */
> + return -ENXIO;
> +
> + uart->port.irq = res2->start;
> + uart->port.dev = &pdev->dev;
> + uart->port.iotype = UPIO_MEM;
> + uart->port.flags = UPF_BOOT_AUTOCONF;
> + uart->port.line = pdev->id;
> + uart->port.ops = &arc_serial_pops;
> +
> + uart->port.uartclk = plat_data[1];
> + uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
> +
> + /*
> + * uart_insert_char( ) uses it in decideding whether to ignore a
> + * char or not. Explicitly setting it here, removes the subtelty
> + */
> + uart->port.ignore_status_mask = 0;
> +
> + /* Real Hardware vs. emulated to work around a bug */
> + uart->is_emulated = !!plat_data[2];
> +
> + return 0;
> +}
> +
> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
> +
> +static int __devinit arc_serial_console_setup(struct console *co, char *options)
> +{
> + struct uart_port *port;
> + int baud = 115200;
> + int bits = 8;
> + int parity = 'n';
> + int flow = 'n';
> +
> + if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
> + return -ENODEV;
> +
> + /*
> + * The uart port backing the console (e.g. ttyARC1) might not have been
> + * init yet. If so, defer the console setup to after the port.
> + */
> + port = &arc_uart_ports[co->index].port;
> + if (!port->membase)
> + return -ENODEV;
> +
> + if (options)
> + uart_parse_options(options, &baud, &parity, &bits, &flow);
> +
> + /*
> + * Serial core will call port->ops->set_termios( )
> + * which will set the baud reg
> + */
> + return uart_set_options(port, co, baud, parity, bits, flow);
> +}
> +
> +static void arc_serial_console_putchar(struct uart_port *port, int ch)
> +{
> + arc_serial_poll_putchar(port, (unsigned char)ch);
> +}
> +
> +/*
> + * Interrupts are disabled on entering
> + */
> +static void arc_serial_console_write(struct console *co, const char *s,
> + unsigned int count)
> +{
> + struct uart_port *port = &arc_uart_ports[co->index].port;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> + uart_console_write(port, s, count, arc_serial_console_putchar);
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +static struct console arc_console = {
> + .name = ARC_SERIAL_DEV_NAME,
> + .write = arc_serial_console_write,
> + .device = uart_console_device,
> + .setup = arc_serial_console_setup,
> + .flags = CON_PRINTBUFFER,
> + .index = -1,
> + .data = &arc_uart_driver
> +};
> +
> +static __init void early_serial_write(struct console *con, const char *s,
> + unsigned int n)
> +{
> + struct uart_port *port = &arc_uart_ports[con->index].port;
> + unsigned int i;
> +
> + for (i = 0; i < n; i++, s++) {
> + if (*s == '\n')
> + arc_serial_poll_putchar(port, '\r');
> + arc_serial_poll_putchar(port, *s);
> + }
> +}
> +
> +static struct __initdata console arc_early_serial_console = {
> + .name = "early_ARCuart",
> + .write = early_serial_write,
> + .flags = CON_PRINTBUFFER | CON_BOOT,
> + .index = -1
> +};
> +
> +static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
> +{
> + arc_early_serial_console.index = pdev->id;
> +
> + arc_uart_init_one(pdev, &arc_uart_ports[pdev->id]);
> +
> + arc_serial_console_setup(&arc_early_serial_console, NULL);
> +
> + register_console(&arc_early_serial_console);
> + return 0;
> +}
> +#else
> +static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
> +{
> + return -ENODEV;
> +}
> +#endif /* CONFIG_SERIAL_ARC_CONSOLE */
> +
> +static int __devinit arc_serial_probe(struct platform_device *pdev)
> +{
> + struct arc_uart_port *uart;
> + int rc;
> +
> + if (is_early_platform_device(pdev))
> + return arc_serial_probe_earlyprintk(pdev);
> +
> + uart = &arc_uart_ports[pdev->id];
> + rc = arc_uart_init_one(pdev, uart);
> + if (rc)
> + return rc;
> +
> + return uart_add_one_port(&arc_uart_driver, &uart->port);
> +}
> +
> +static int __devexit arc_serial_remove(struct platform_device *pdev)
> +{
> + /* This will never be called */
> + return 0;
> +}
> +
> +static struct platform_driver arc_platform_driver = {
> + .probe = arc_serial_probe,
> + .remove = __devexit_p(arc_serial_remove),
> + .driver = {
> + .name = DRIVER_NAME,
> + .owner = THIS_MODULE,
> + },
> +};
> +
> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
> +/*
> + * Register an early platform driver of "earlyprintk" class.
> + * ARCH platform code installs the driver and probes the early devices
> + * The installation could rely on user specifying earlyprintk=xyx in cmd line
> + * or it could be done independently, for all "earlyprintk" class drivers.
> + * [see arch/arc/plat-arcfpga/platform.c]
> + */
> +early_platform_init("earlyprintk", &arc_platform_driver);
> +
> +#endif /* CONFIG_SERIAL_ARC_CONSOLE */
> +
> +static int __init arc_serial_init(void)
> +{
> + int ret;
> +
> + pr_info("Serial: ARC serial driver: platform register\n");
please remove this line, it's just useless IMHO.
--
balbi
On Friday 26 October 2012 05:40 PM, Felipe Balbi wrote:
> On Fri, Oct 26, 2012 at 05:33:16PM +0530, [email protected] wrote:
>> From: Vineet Gupta <[email protected]>
>>
>> Driver for non-standard on-chip UART, instantiated in the ARC (Synopsys)
>> FPGA Boards such as ARCAngel4/ML50x
>>
>> Signed-off-by: Vineet Gupta <[email protected]>
>> ---
>> drivers/tty/serial/Kconfig | 23 ++
>> drivers/tty/serial/Makefile | 1 +
>> drivers/tty/serial/arc_uart.c | 754 ++++++++++++++++++++++++++++++++++++++
>> include/uapi/linux/serial_core.h | 2 +
>> 4 files changed, 780 insertions(+), 0 deletions(-)
>> create mode 100644 drivers/tty/serial/arc_uart.c
>>
>> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
>> index 2a53be5..b176801 100644
>> --- a/drivers/tty/serial/Kconfig
>> +++ b/drivers/tty/serial/Kconfig
>> @@ -1423,4 +1423,27 @@ config SERIAL_EFM32_UART_CONSOLE
>> depends on SERIAL_EFM32_UART=y
>> select SERIAL_CORE_CONSOLE
>>
>> +config SERIAL_ARC
>> + tristate "ARC UART driver support"
>> + select SERIAL_CORE
>> + help
>> + Driver for on-chip UART for ARC(Synopsys) for the legacy
>> + FPGA Boards (ML50x/ARCAngel4)
>> +
>> +config SERIAL_ARC_CONSOLE
>> + bool "Console on ARC UART"
>> + depends on SERIAL_ARC=y
>> + select SERIAL_CORE_CONSOLE
>> + help
>> + Enable system Console on ARC UART
>> +
>> +config SERIAL_ARC_NR_PORTS
>> + int "Number of ARC UART ports"
>> + depends on SERIAL_ARC
>> + range 1 3
>> + default "1"
>> + help
>> + Set this to the number of serial ports you want the driver
>> + to support.
>> +
>> endmenu
>> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
>> index 4f694da..df1b998 100644
>> --- a/drivers/tty/serial/Makefile
>> +++ b/drivers/tty/serial/Makefile
>> @@ -82,3 +82,4 @@ obj-$(CONFIG_SERIAL_XILINX_PS_UART) += xilinx_uartps.o
>> obj-$(CONFIG_SERIAL_SIRFSOC) += sirfsoc_uart.o
>> obj-$(CONFIG_SERIAL_AR933X) += ar933x_uart.o
>> obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
>> +obj-$(CONFIG_SERIAL_ARC) += arc_uart.o
>> diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
>> new file mode 100644
>> index 0000000..c12efae
>> --- /dev/null
>> +++ b/drivers/tty/serial/arc_uart.c
>> @@ -0,0 +1,754 @@
>> +/*
>> + * ARC On-Chip(fpga) UART Driver
>> + *
>> + * Copyright (C) 2010-2012 Synopsys, Inc. (http://www.synopsys.com)
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * vineetg: July 10th 2012
>> + * -Decoupled the driver from arch/arc
>> + * +Using platform_get_resource() for irq/membase (thx to bfin_uart.c)
>> + * +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
>> + *
>> + * Vineetg: Aug 21st 2010
>> + * -Is uart_tx_stopped() not done in tty write path as it has already been
>> + * taken care of, in serial core
>> + *
>> + * Vineetg: Aug 18th 2010
>> + * -New Serial Core based ARC UART driver
>> + * -Derived largely from blackfin driver albiet with some major tweaks
>> + *
>> + * TODO:
>> + * -check if sysreq works
>> + */
>> +
>> +#if defined(CONFIG_SERIAL_ARC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
>> +#define SUPPORT_SYSRQ
>> +#endif
>> +
>> +#include <linux/module.h>
>> +#include <linux/serial.h>
>> +#include <linux/console.h>
>> +#include <linux/sysrq.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/tty.h>
>> +#include <linux/tty_flip.h>
>> +#include <linux/serial_core.h>
>> +#include <linux/io.h>
>> +
>> +/*************************************
>> + * ARC UART Hardware Specs
>> + ************************************/
>> +#define ARC_UART_TX_FIFO_SIZE 1
>> +
>> +/*
>> + * UART Register set (this is not a Standards Compliant IP)
>> + * Also each reg is Word aligned, but only 8 bits wide
>> + */
>> +#define R_ID0 0
>> +#define R_ID1 4
>> +#define R_ID2 8
>> +#define R_ID3 12
>> +#define R_DATA 16
>> +#define R_STS 20
>> +#define R_BAUDL 24
>> +#define R_BAUDH 28
>> +
>> +/* Bits for UART Status Reg (R/W) */
>> +#define RXIENB 0x04 /* Receive Interrupt Enable */
>> +#define TXIENB 0x40 /* Transmit Interrupt Enable */
>> +
>> +#define RXEMPTY 0x20 /* Receive FIFO Empty: No char receivede */
>> +#define TXEMPTY 0x80 /* Transmit FIFO Empty, thus char can be written into */
>> +
>> +#define RXFULL 0x08 /* Receive FIFO full */
>> +#define RXFULL1 0x10 /* Receive FIFO has space for 1 char (tot space=4) */
>> +
>> +#define RXFERR 0x01 /* Frame Error: Stop Bit not detected */
>> +#define RXOERR 0x02 /* OverFlow Err: Char recv but RXFULL still set */
>> +
>> +/* Uart bit fiddling helpers: lowest level */
>> +#define RBASE(uart, reg) (uart->port.membase + reg)
>> +#define UART_REG_SET(u, r, v) writeb((v), RBASE(u, r))
>> +#define UART_REG_GET(u, r) readb(RBASE(u, r))
>> +
>> +#define UART_REG_OR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) | (v))
>> +#define UART_REG_CLR(u, r, v) UART_REG_SET(u, r, UART_REG_GET(u, r) & ~(v))
>> +
>> +/* Uart bit fiddling helpers: API level */
>> +#define UART_SET_DATA(uart, val) UART_REG_SET(uart, R_DATA, val)
>> +#define UART_GET_DATA(uart) UART_REG_GET(uart, R_DATA)
>> +
>> +#define UART_SET_BAUDH(uart, val) UART_REG_SET(uart, R_BAUDH, val)
>> +#define UART_SET_BAUDL(uart, val) UART_REG_SET(uart, R_BAUDL, val)
>> +
>> +#define UART_CLR_STATUS(uart, val) UART_REG_CLR(uart, R_STS, val)
>> +#define UART_GET_STATUS(uart) UART_REG_GET(uart, R_STS)
>> +
>> +#define UART_ALL_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB|TXIENB)
>> +#define UART_RX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, RXIENB)
>> +#define UART_TX_IRQ_DISABLE(uart) UART_REG_CLR(uart, R_STS, TXIENB)
>> +
>> +#define UART_ALL_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB|TXIENB)
>> +#define UART_RX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, RXIENB)
>> +#define UART_TX_IRQ_ENABLE(uart) UART_REG_OR(uart, R_STS, TXIENB)
>> +
>> +#define ARC_SERIAL_DEV_NAME "ttyARC"
>> +
>> +struct arc_uart_port {
>> + struct uart_port port;
>> + unsigned long baud;
>> + int is_emulated; /* H/w vs. Instruction Set Simulator */
>> +};
>> +
>> +static struct arc_uart_port arc_uart_ports[CONFIG_SERIAL_ARC_NR_PORTS];
>> +
>> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
>> +static struct console arc_console;
>> +#endif
>> +
>> +#define DRIVER_NAME "arc-uart"
>> +
>> +static struct uart_driver arc_uart_driver = {
>> + .owner = THIS_MODULE,
>> + .driver_name = DRIVER_NAME,
>> + .dev_name = ARC_SERIAL_DEV_NAME,
>> + .major = 0,
>> + .minor = 0,
>> + .nr = CONFIG_SERIAL_ARC_NR_PORTS,
>> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
>> + .cons = &arc_console,
>> +#else
>> + .cons = NULL,
> else branch isn't necessary. The structure is declared static and
> everything is initialized to zero unless overwritten by code.
Correct - Fixed in next ver !
>> +#endif
>> +};
>> +
>> +static void arc_serial_stop_rx(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> I would suggest using container_of() here. It's very unlikely to happen,
> but if another field is added before struct uart_port member in your
> structure, this will break.
I agree that container_of() would make it future safe - but I don't
foresee any significant changes to driver specially the arc_uart_port
structure.
>> + UART_RX_IRQ_DISABLE(uart);
>> +}
>> +
>> +static void arc_serial_stop_tx(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> +
>> + while (!(UART_GET_STATUS(uart) & TXEMPTY))
>> + cpu_relax();
>> +
>> + UART_TX_IRQ_DISABLE(uart);
>> +}
>> +
>> +/*
>> + * Return TIOCSER_TEMT when transmitter is not busy.
>> + */
>> +static unsigned int arc_serial_tx_empty(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> + unsigned int stat;
>> +
>> + stat = UART_GET_STATUS(uart);
>> + if (stat & TXEMPTY)
>> + return TIOCSER_TEMT;
>> + else
>> + return 0;
> else is unnecessary you can convert this into:
>
> if (stat & TXEMPTY)
> return TIOCSER_TEMT;
>
> return 0;
OK !
>
>> +}
>> +
>> +/*
>> + * Driver internal routine, used by both tty(serial core) as well as tx-isr
>> + * -Called under spinlock in either cases
>> + * -also tty->stopped / tty->hw_stopped has already been checked
>> + * = by uart_start( ) before calling us
>> + * = tx_ist checks that too before calling
>> + */
>> +static void arc_serial_tx_chars(struct arc_uart_port *uart)
>> +{
>> + struct circ_buf *xmit = &uart->port.state->xmit;
>> + int sent = 0;
>> + unsigned char ch;
>> +
>> + if (unlikely(uart->port.x_char)) {
>> + UART_SET_DATA(uart, uart->port.x_char);
>> + uart->port.icount.tx++;
>> + uart->port.x_char = 0;
>> + sent = 1;
>> + } else if (xmit->tail != xmit->head) { /* TODO: uart_circ_empty */
>> + ch = xmit->buf[xmit->tail];
>> + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
>> + uart->port.icount.tx++;
>> + while (!(UART_GET_STATUS(uart) & TXEMPTY))
>> + cpu_relax();
>> + UART_SET_DATA(uart, ch);
>> + sent = 1;
>> + }
>> +
>> + /*
>> + * If num chars in xmit buffer are too few, ask tty layer for more.
>> + * By Hard ISR to schedule processing in software interrupt part
>> + */
>> + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
>> + uart_write_wakeup(&uart->port);
>> +
>> + if (sent)
>> + UART_TX_IRQ_ENABLE(uart);
>> +}
>> +
>> +/*
>> + * port is locked and interrupts are disabled
>> + * uart_start( ) calls us under the port spinlock irqsave
>> + */
>> +static void arc_serial_start_tx(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> +
>> + arc_serial_tx_chars(uart);
>> +}
>> +
>> +static void arc_serial_rx_chars(struct arc_uart_port *uart)
>> +{
>> + struct tty_struct *tty = tty_port_tty_get(&uart->port.state->port);
>> + unsigned int status, ch, flg = 0;
>> +
>> + if (!tty)
>> + return;
> can this really happen ? why would you receive characters while tty is
> NULL ?
Since we are getting a ref to tty - it makes sense to check if the
pointer is not NULL. Alan had pointed to a possible hangup race which
could yield a NULL tty. But I'm not really an expert in serial core to
be sure if at all this will happen - so added the check.
>> + /*
>> + * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
>> + * is very subtle. Here's how ...
>> + * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
>> + * driver reads the DATA Reg and keeps doing that in a loop, until
>> + * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
>> + * before RX-EMPTY=0, implies some sort of buffering going on in the
>> + * controller, which is indeed the Rx-FIFO.
>> + */
>> + while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
>> +
>> + ch = UART_GET_DATA(uart);
>> + uart->port.icount.rx++;
>> +
>> + if (unlikely(status & (RXOERR | RXFERR))) {
>> + if (status & RXOERR) {
>> + uart->port.icount.overrun++;
>> + flg = TTY_OVERRUN;
>> + UART_CLR_STATUS(uart, RXOERR);
>> + }
>> +
>> + if (status & RXFERR) {
>> + uart->port.icount.frame++;
>> + flg = TTY_FRAME;
>> + UART_CLR_STATUS(uart, RXFERR);
>> + }
>> + } else
>> + flg = TTY_NORMAL;
>> +
>> + if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
>> + goto done;
>> +
>> + uart_insert_char(&uart->port, status, RXOERR, ch, flg);
>> +
>> +done:
>> + tty_flip_buffer_push(tty);
>> + }
>> +
>> + tty_kref_put(tty);
>> +}
>> +
>> +/*
>> + * A note on the Interrupt handling state machine of this driver
>> + *
>> + * kernel printk writes funnel thru the console driver framework and in order
>> + * to keep things simple as well as efficient, it writes to UART in polled
>> + * mode, in one shot, and exits.
>> + *
>> + * OTOH, Userland output (via tty layer), uses interrupt based writes as there
>> + * can be undeterministic delay between char writes.
>> + *
>> + * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
>> + * disabled.
>> + *
>> + * When tty has some data to send out, serial core calls driver's start_tx
>> + * which
>> + * -checks-if-tty-buffer-has-char-to-send
>> + * -writes-data-to-uart
>> + * -enable-tx-intr
>> + *
>> + * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
>> + * The first thing Tx ISR does is disable further Tx interrupts (as this could
>> + * be the last char to send, before settling down into the quiet polled mode).
>> + * It then calls the exact routine used by tty layer write to send out any
>> + * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
>> + * of no data, it remains disabled.
>> + * This is how the transmit state machine is dynamically switched on/off
>> + */
>> +
>> +static irqreturn_t arc_serial_isr(int irq, void *dev_id)
>> +{
>> + struct arc_uart_port *uart = dev_id;
>> + unsigned int status;
>> +
>> + status = UART_GET_STATUS(uart);
>> +
>> + /*
>> + * Single IRQ for both Rx (data available) Tx (room available) Interrupt
>> + * notifications from the UART Controller.
>> + * To demultiplex between the two, we check the relevant bits
>> + */
>> + if ((status & RXIENB) && !(status & RXEMPTY)) {
>> +
>> + /* already in ISR, no need of xx_irqsave */
>> + spin_lock(&uart->port.lock);
>> + arc_serial_rx_chars(uart);
>> + spin_unlock(&uart->port.lock);
>> + }
>> +
>> + if ((status & TXIENB) && (status & TXEMPTY)) {
>> +
>> + /* Unconditionally disable further Tx-Interrupts.
>> + * will be enabled by tx_chars() if needed.
>> + */
>> + UART_TX_IRQ_DISABLE(uart);
>> +
>> + spin_lock(&uart->port.lock);
>> +
>> + if (!uart_tx_stopped(&uart->port))
>> + arc_serial_tx_chars(uart);
>> +
>> + spin_unlock(&uart->port.lock);
>> + }
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static unsigned int arc_serial_get_mctrl(struct uart_port *port)
>> +{
>> + /*
>> + * Pretend we have a Modem status reg and following bits are
>> + * always set, to satify the serial core state machine
>> + * (DSR) Data Set Ready
>> + * (CTS) Clear To Send
>> + * (CAR) Carrier Detect
>> + */
>> + return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
>> +}
>> +
>> +static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
>> +{
>> + /* MCR not present */
>> +}
>> +
>> +/* Enable Modem Status Interrupts */
>> +
>> +static void arc_serial_enable_ms(struct uart_port *port)
>> +{
>> + /* MSR not present */
>> +}
>> +
>> +static void arc_serial_break_ctl(struct uart_port *port, int break_state)
>> +{
>> + /* ARC UART doesn't support sending Break signal */
>> +}
>> +
>> +static int arc_serial_startup(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> +
>> + /* Before we hook up the ISR, Disable all UART Interrupts */
>> + UART_ALL_IRQ_DISABLE(uart);
>> +
>> + if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
>> + uart)) {
>> + pr_warn("Unable to attach ARC UART interrupt\n");
>> + return -EBUSY;
>> + }
>> +
>> + UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
>> +
>> + return 0;
>> +}
>> +
>> +/* This is not really needed */
>> +static void arc_serial_shutdown(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> + free_irq(uart->port.irq, uart);
>> +}
>> +
>> +static void
>> +arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
>> + struct ktermios *old)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> + unsigned int baud, uartl, uarth, hw_val;
>> + unsigned long flags;
>> +
>> + /*
>> + * Use the generic handler so that any specially encoded baud rates
>> + * such as SPD_xx flags or "%B0" can be handled
>> + * Max Baud I suppose will not be more than current 115K * 4
>> + * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
>> + * spread over two 8-bit registers
>> + */
>> + baud = uart_get_baud_rate(port, new, old, 0, 460800);
>> +
>> + hw_val = port->uartclk / (uart->baud * 4) - 1;
>> + uartl = hw_val & 0xFF;
>> + uarth = (hw_val >> 8) & 0xFF;
>> +
>> + /*
>> + * UART ISS(Instruction Set simulator) emulation has a subtle bug:
>> + * A existing value of Baudh = 0 is used as a indication to startup
>> + * it's internal state machine.
>> + * Thus if baudh is set to 0, 2 times, it chokes.
>> + * This happens with BAUD=115200 and the formaula above
>> + * Until that is fixed, when running on ISS, we will set baudh to !0
>> + */
>> + if (uart->is_emulated)
>> + uarth = 1;
>> +
>> + spin_lock_irqsave(&port->lock, flags);
>> +
>> + UART_ALL_IRQ_DISABLE(uart);
>> +
>> + UART_SET_BAUDL(uart, uartl);
>> + UART_SET_BAUDH(uart, uarth);
>> +
>> + UART_RX_IRQ_ENABLE(uart);
>> +
>> + /*
>> + * UART doesn't support Parity/Hardware Flow Control;
>> + * Only supports 8N1 character size
>> + */
>> + new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
>> + new->c_cflag |= CS8;
>> +
>> + if (old)
>> + tty_termios_copy_hw(new, old);
>> +
>> + /* Don't rewrite B0 */
>> + if (tty_termios_baud_rate(new))
>> + tty_termios_encode_baud_rate(new, baud, baud);
>> +
>> + uart_update_timeout(port, new->c_cflag, baud);
>> +
>> + spin_unlock_irqrestore(&port->lock, flags);
>> +}
>> +
>> +static const char *arc_serial_type(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> +
>> + return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
>> +}
>> +
>> +/*
>> + * Release the memory region(s) being used by 'port'.
>> + */
>> +static void arc_serial_release_port(struct uart_port *port)
>> +{
>> +}
>> +
>> +/*
>> + * Request the memory region(s) being used by 'port'.
>> + */
>> +static int arc_serial_request_port(struct uart_port *port)
>> +{
>> + return 0;
>> +}
>> +
>> +/*
>> + * Verify the new serial_struct (for TIOCSSERIAL).
>> + */
>> +static int
>> +arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
>> +{
>> + return 0;
>> +}
> why all these empty functions with wrong comments above them ??
Copy/paste cruft. Empty functions deleted in next ver !
Regarding verify_port, I'm not sure whether it needs to elaborately
check for PORT_UNKNOWN -> PORT_ARC or can we simply continue to return
0. But IMHO the comment in there is right. No ?
>> +/*
>> + * Configure/autoconfigure the port.
>> + */
>> +static void arc_serial_config_port(struct uart_port *port, int flags)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> +
>> + if (flags & UART_CONFIG_TYPE &&
>> + arc_serial_request_port(&uart->port) == 0)
>> + uart->port.type = PORT_ARC;
>> +}
>> +
>> +#if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
>> +
>> +static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> +
>> + while (!(UART_GET_STATUS(uart) & TXEMPTY))
>> + cpu_relax();
>> +
>> + UART_SET_DATA(uart, chr);
>> +}
>> +#endif
>> +
>> +#ifdef CONFIG_CONSOLE_POLL
>> +static int arc_serial_poll_getchar(struct uart_port *port)
>> +{
>> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
>> + unsigned char chr;
>> +
>> + while (!(UART_GET_STATUS(uart) & RXEMPTY))
>> + cpu_relax();
>> +
>> + chr = UART_GET_DATA(uart);
>> + return chr;
>> +}
>> +#endif
>> +
>> +static struct uart_ops arc_serial_pops = {
>> + .tx_empty = arc_serial_tx_empty,
>> + .set_mctrl = arc_serial_set_mctrl,
>> + .get_mctrl = arc_serial_get_mctrl,
>> + .stop_tx = arc_serial_stop_tx,
>> + .start_tx = arc_serial_start_tx,
>> + .stop_rx = arc_serial_stop_rx,
>> + .enable_ms = arc_serial_enable_ms,
>> + .break_ctl = arc_serial_break_ctl,
>> + .startup = arc_serial_startup,
>> + .shutdown = arc_serial_shutdown,
>> + .set_termios = arc_serial_set_termios,
>> + .type = arc_serial_type,
>> + .release_port = arc_serial_release_port,
>> + .request_port = arc_serial_request_port,
>> + .config_port = arc_serial_config_port,
>> + .verify_port = arc_serial_verify_port,
>> +#ifdef CONFIG_CONSOLE_POLL
>> + .poll_put_char = arc_serial_poll_putchar,
>> + .poll_get_char = arc_serial_poll_getchar,
>> +#endif
>> +};
>> +
>> +static int __devinit
>> +arc_uart_init_one(struct platform_device *pdev, struct arc_uart_port *uart)
>> +{
>> + struct resource *res, *res2;
>> + unsigned long *plat_data;
>> +
>> + if (pdev->id < 0 || pdev->id >= CONFIG_SERIAL_ARC_NR_PORTS) {
>> + dev_err(&pdev->dev, "Wrong uart platform device id.\n");
>> + return -ENOENT;
>> + }
>> +
>> + plat_data = ((unsigned long *)(pdev->dev.platform_data));
>> + uart->baud = plat_data[0];
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + if (!res)
>> + return -ENODEV;
>> +
>> + res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>> + if (!res2)
>> + return -ENODEV;
>> +
>> + uart->port.mapbase = res->start;
>> + uart->port.membase = ioremap_nocache(res->start, resource_size(res));
>> + if (!uart->port.membase)
>> + /* No point of pr_err since UART itself is hosed here */
>> + return -ENXIO;
>> +
>> + uart->port.irq = res2->start;
>> + uart->port.dev = &pdev->dev;
>> + uart->port.iotype = UPIO_MEM;
>> + uart->port.flags = UPF_BOOT_AUTOCONF;
>> + uart->port.line = pdev->id;
>> + uart->port.ops = &arc_serial_pops;
>> +
>> + uart->port.uartclk = plat_data[1];
>> + uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
>> +
>> + /*
>> + * uart_insert_char( ) uses it in decideding whether to ignore a
>> + * char or not. Explicitly setting it here, removes the subtelty
>> + */
>> + uart->port.ignore_status_mask = 0;
>> +
>> + /* Real Hardware vs. emulated to work around a bug */
>> + uart->is_emulated = !!plat_data[2];
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
>> +
>> +static int __devinit arc_serial_console_setup(struct console *co, char *options)
>> +{
>> + struct uart_port *port;
>> + int baud = 115200;
>> + int bits = 8;
>> + int parity = 'n';
>> + int flow = 'n';
>> +
>> + if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
>> + return -ENODEV;
>> +
>> + /*
>> + * The uart port backing the console (e.g. ttyARC1) might not have been
>> + * init yet. If so, defer the console setup to after the port.
>> + */
>> + port = &arc_uart_ports[co->index].port;
>> + if (!port->membase)
>> + return -ENODEV;
>> +
>> + if (options)
>> + uart_parse_options(options, &baud, &parity, &bits, &flow);
>> +
>> + /*
>> + * Serial core will call port->ops->set_termios( )
>> + * which will set the baud reg
>> + */
>> + return uart_set_options(port, co, baud, parity, bits, flow);
>> +}
>> +
>> +static void arc_serial_console_putchar(struct uart_port *port, int ch)
>> +{
>> + arc_serial_poll_putchar(port, (unsigned char)ch);
>> +}
>> +
>> +/*
>> + * Interrupts are disabled on entering
>> + */
>> +static void arc_serial_console_write(struct console *co, const char *s,
>> + unsigned int count)
>> +{
>> + struct uart_port *port = &arc_uart_ports[co->index].port;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&port->lock, flags);
>> + uart_console_write(port, s, count, arc_serial_console_putchar);
>> + spin_unlock_irqrestore(&port->lock, flags);
>> +}
>> +
>> +static struct console arc_console = {
>> + .name = ARC_SERIAL_DEV_NAME,
>> + .write = arc_serial_console_write,
>> + .device = uart_console_device,
>> + .setup = arc_serial_console_setup,
>> + .flags = CON_PRINTBUFFER,
>> + .index = -1,
>> + .data = &arc_uart_driver
>> +};
>> +
>> +static __init void early_serial_write(struct console *con, const char *s,
>> + unsigned int n)
>> +{
>> + struct uart_port *port = &arc_uart_ports[con->index].port;
>> + unsigned int i;
>> +
>> + for (i = 0; i < n; i++, s++) {
>> + if (*s == '\n')
>> + arc_serial_poll_putchar(port, '\r');
>> + arc_serial_poll_putchar(port, *s);
>> + }
>> +}
>> +
>> +static struct __initdata console arc_early_serial_console = {
>> + .name = "early_ARCuart",
>> + .write = early_serial_write,
>> + .flags = CON_PRINTBUFFER | CON_BOOT,
>> + .index = -1
>> +};
>> +
>> +static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
>> +{
>> + arc_early_serial_console.index = pdev->id;
>> +
>> + arc_uart_init_one(pdev, &arc_uart_ports[pdev->id]);
>> +
>> + arc_serial_console_setup(&arc_early_serial_console, NULL);
>> +
>> + register_console(&arc_early_serial_console);
>> + return 0;
>> +}
>> +#else
>> +static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
>> +{
>> + return -ENODEV;
>> +}
>> +#endif /* CONFIG_SERIAL_ARC_CONSOLE */
>> +
>> +static int __devinit arc_serial_probe(struct platform_device *pdev)
>> +{
>> + struct arc_uart_port *uart;
>> + int rc;
>> +
>> + if (is_early_platform_device(pdev))
>> + return arc_serial_probe_earlyprintk(pdev);
>> +
>> + uart = &arc_uart_ports[pdev->id];
>> + rc = arc_uart_init_one(pdev, uart);
>> + if (rc)
>> + return rc;
>> +
>> + return uart_add_one_port(&arc_uart_driver, &uart->port);
>> +}
>> +
>> +static int __devexit arc_serial_remove(struct platform_device *pdev)
>> +{
>> + /* This will never be called */
>> + return 0;
>> +}
>> +
>> +static struct platform_driver arc_platform_driver = {
>> + .probe = arc_serial_probe,
>> + .remove = __devexit_p(arc_serial_remove),
>> + .driver = {
>> + .name = DRIVER_NAME,
>> + .owner = THIS_MODULE,
>> + },
>> +};
>> +
>> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
>> +/*
>> + * Register an early platform driver of "earlyprintk" class.
>> + * ARCH platform code installs the driver and probes the early devices
>> + * The installation could rely on user specifying earlyprintk=xyx in cmd line
>> + * or it could be done independently, for all "earlyprintk" class drivers.
>> + * [see arch/arc/plat-arcfpga/platform.c]
>> + */
>> +early_platform_init("earlyprintk", &arc_platform_driver);
>> +
>> +#endif /* CONFIG_SERIAL_ARC_CONSOLE */
>> +
>> +static int __init arc_serial_init(void)
>> +{
>> + int ret;
>> +
>> + pr_info("Serial: ARC serial driver: platform register\n");
> please remove this line, it's just useless IMHO.
It has helped me enough in past when debugging the uncoupling of driver
from ARC platform code. I'd rather keep it !
Many thanks for your review ! Once I see your reply I'll respin the next
version.
-Vineet
hi,
On Fri, Oct 26, 2012 at 06:17:26PM +0530, Vineet Gupta wrote:
> >> +#endif
> >> +};
> >> +
> >> +static void arc_serial_stop_rx(struct uart_port *port)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> > I would suggest using container_of() here. It's very unlikely to happen,
> > but if another field is added before struct uart_port member in your
> > structure, this will break.
>
> I agree that container_of() would make it future safe - but I don't
> foresee any significant changes to driver specially the arc_uart_port
> structure.
I would still do it. The way code is right now, container_of() will be
optmized into the same cast you have today, so no impacts there.
> >> +static void arc_serial_rx_chars(struct arc_uart_port *uart)
> >> +{
> >> + struct tty_struct *tty = tty_port_tty_get(&uart->port.state->port);
> >> + unsigned int status, ch, flg = 0;
> >> +
> >> + if (!tty)
> >> + return;
> > can this really happen ? why would you receive characters while tty is
> > NULL ?
>
> Since we are getting a ref to tty - it makes sense to check if the
> pointer is not NULL. Alan had pointed to a possible hangup race which
> could yield a NULL tty. But I'm not really an expert in serial core to
> be sure if at all this will happen - so added the check.
fair enough...
> >> + /*
> >> + * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
> >> + * is very subtle. Here's how ...
> >> + * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,
> >> + * driver reads the DATA Reg and keeps doing that in a loop, until
> >> + * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,
> >> + * before RX-EMPTY=0, implies some sort of buffering going on in the
> >> + * controller, which is indeed the Rx-FIFO.
> >> + */
> >> + while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
> >> +
> >> + ch = UART_GET_DATA(uart);
> >> + uart->port.icount.rx++;
> >> +
> >> + if (unlikely(status & (RXOERR | RXFERR))) {
> >> + if (status & RXOERR) {
> >> + uart->port.icount.overrun++;
> >> + flg = TTY_OVERRUN;
> >> + UART_CLR_STATUS(uart, RXOERR);
> >> + }
> >> +
> >> + if (status & RXFERR) {
> >> + uart->port.icount.frame++;
> >> + flg = TTY_FRAME;
> >> + UART_CLR_STATUS(uart, RXFERR);
> >> + }
> >> + } else
> >> + flg = TTY_NORMAL;
> >> +
> >> + if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
> >> + goto done;
> >> +
> >> + uart_insert_char(&uart->port, status, RXOERR, ch, flg);
> >> +
> >> +done:
> >> + tty_flip_buffer_push(tty);
> >> + }
> >> +
> >> + tty_kref_put(tty);
> >> +}
> >> +
> >> +/*
> >> + * A note on the Interrupt handling state machine of this driver
> >> + *
> >> + * kernel printk writes funnel thru the console driver framework and in order
> >> + * to keep things simple as well as efficient, it writes to UART in polled
> >> + * mode, in one shot, and exits.
> >> + *
> >> + * OTOH, Userland output (via tty layer), uses interrupt based writes as there
> >> + * can be undeterministic delay between char writes.
> >> + *
> >> + * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
> >> + * disabled.
> >> + *
> >> + * When tty has some data to send out, serial core calls driver's start_tx
> >> + * which
> >> + * -checks-if-tty-buffer-has-char-to-send
> >> + * -writes-data-to-uart
> >> + * -enable-tx-intr
> >> + *
> >> + * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
> >> + * The first thing Tx ISR does is disable further Tx interrupts (as this could
> >> + * be the last char to send, before settling down into the quiet polled mode).
> >> + * It then calls the exact routine used by tty layer write to send out any
> >> + * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
> >> + * of no data, it remains disabled.
> >> + * This is how the transmit state machine is dynamically switched on/off
> >> + */
> >> +
> >> +static irqreturn_t arc_serial_isr(int irq, void *dev_id)
> >> +{
> >> + struct arc_uart_port *uart = dev_id;
> >> + unsigned int status;
> >> +
> >> + status = UART_GET_STATUS(uart);
> >> +
> >> + /*
> >> + * Single IRQ for both Rx (data available) Tx (room available) Interrupt
> >> + * notifications from the UART Controller.
> >> + * To demultiplex between the two, we check the relevant bits
> >> + */
> >> + if ((status & RXIENB) && !(status & RXEMPTY)) {
> >> +
> >> + /* already in ISR, no need of xx_irqsave */
> >> + spin_lock(&uart->port.lock);
> >> + arc_serial_rx_chars(uart);
> >> + spin_unlock(&uart->port.lock);
> >> + }
> >> +
> >> + if ((status & TXIENB) && (status & TXEMPTY)) {
> >> +
> >> + /* Unconditionally disable further Tx-Interrupts.
> >> + * will be enabled by tx_chars() if needed.
> >> + */
> >> + UART_TX_IRQ_DISABLE(uart);
> >> +
> >> + spin_lock(&uart->port.lock);
> >> +
> >> + if (!uart_tx_stopped(&uart->port))
> >> + arc_serial_tx_chars(uart);
> >> +
> >> + spin_unlock(&uart->port.lock);
> >> + }
> >> +
> >> + return IRQ_HANDLED;
> >> +}
> >> +
> >> +static unsigned int arc_serial_get_mctrl(struct uart_port *port)
> >> +{
> >> + /*
> >> + * Pretend we have a Modem status reg and following bits are
> >> + * always set, to satify the serial core state machine
> >> + * (DSR) Data Set Ready
> >> + * (CTS) Clear To Send
> >> + * (CAR) Carrier Detect
> >> + */
> >> + return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
> >> +}
> >> +
> >> +static void arc_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
> >> +{
> >> + /* MCR not present */
> >> +}
> >> +
> >> +/* Enable Modem Status Interrupts */
> >> +
> >> +static void arc_serial_enable_ms(struct uart_port *port)
> >> +{
> >> + /* MSR not present */
> >> +}
> >> +
> >> +static void arc_serial_break_ctl(struct uart_port *port, int break_state)
> >> +{
> >> + /* ARC UART doesn't support sending Break signal */
> >> +}
> >> +
> >> +static int arc_serial_startup(struct uart_port *port)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> >> +
> >> + /* Before we hook up the ISR, Disable all UART Interrupts */
> >> + UART_ALL_IRQ_DISABLE(uart);
> >> +
> >> + if (request_irq(uart->port.irq, arc_serial_isr, 0, "arc uart rx-tx",
> >> + uart)) {
> >> + pr_warn("Unable to attach ARC UART interrupt\n");
> >> + return -EBUSY;
> >> + }
> >> +
> >> + UART_RX_IRQ_ENABLE(uart); /* Only Rx IRQ enabled to begin with */
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +/* This is not really needed */
> >> +static void arc_serial_shutdown(struct uart_port *port)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> >> + free_irq(uart->port.irq, uart);
> >> +}
> >> +
> >> +static void
> >> +arc_serial_set_termios(struct uart_port *port, struct ktermios *new,
> >> + struct ktermios *old)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> >> + unsigned int baud, uartl, uarth, hw_val;
> >> + unsigned long flags;
> >> +
> >> + /*
> >> + * Use the generic handler so that any specially encoded baud rates
> >> + * such as SPD_xx flags or "%B0" can be handled
> >> + * Max Baud I suppose will not be more than current 115K * 4
> >> + * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)
> >> + * spread over two 8-bit registers
> >> + */
> >> + baud = uart_get_baud_rate(port, new, old, 0, 460800);
> >> +
> >> + hw_val = port->uartclk / (uart->baud * 4) - 1;
> >> + uartl = hw_val & 0xFF;
> >> + uarth = (hw_val >> 8) & 0xFF;
> >> +
> >> + /*
> >> + * UART ISS(Instruction Set simulator) emulation has a subtle bug:
> >> + * A existing value of Baudh = 0 is used as a indication to startup
> >> + * it's internal state machine.
> >> + * Thus if baudh is set to 0, 2 times, it chokes.
> >> + * This happens with BAUD=115200 and the formaula above
> >> + * Until that is fixed, when running on ISS, we will set baudh to !0
> >> + */
> >> + if (uart->is_emulated)
> >> + uarth = 1;
> >> +
> >> + spin_lock_irqsave(&port->lock, flags);
> >> +
> >> + UART_ALL_IRQ_DISABLE(uart);
> >> +
> >> + UART_SET_BAUDL(uart, uartl);
> >> + UART_SET_BAUDH(uart, uarth);
> >> +
> >> + UART_RX_IRQ_ENABLE(uart);
> >> +
> >> + /*
> >> + * UART doesn't support Parity/Hardware Flow Control;
> >> + * Only supports 8N1 character size
> >> + */
> >> + new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);
> >> + new->c_cflag |= CS8;
> >> +
> >> + if (old)
> >> + tty_termios_copy_hw(new, old);
> >> +
> >> + /* Don't rewrite B0 */
> >> + if (tty_termios_baud_rate(new))
> >> + tty_termios_encode_baud_rate(new, baud, baud);
> >> +
> >> + uart_update_timeout(port, new->c_cflag, baud);
> >> +
> >> + spin_unlock_irqrestore(&port->lock, flags);
> >> +}
> >> +
> >> +static const char *arc_serial_type(struct uart_port *port)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> >> +
> >> + return uart->port.type == PORT_ARC ? DRIVER_NAME : NULL;
> >> +}
> >> +
> >> +/*
> >> + * Release the memory region(s) being used by 'port'.
> >> + */
> >> +static void arc_serial_release_port(struct uart_port *port)
> >> +{
> >> +}
> >> +
> >> +/*
> >> + * Request the memory region(s) being used by 'port'.
> >> + */
> >> +static int arc_serial_request_port(struct uart_port *port)
> >> +{
> >> + return 0;
> >> +}
> >> +
> >> +/*
> >> + * Verify the new serial_struct (for TIOCSSERIAL).
> >> + */
> >> +static int
> >> +arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
> >> +{
> >> + return 0;
> >> +}
> > why all these empty functions with wrong comments above them ??
>
> Copy/paste cruft. Empty functions deleted in next ver !
> Regarding verify_port, I'm not sure whether it needs to elaborately
> check for PORT_UNKNOWN -> PORT_ARC or can we simply continue to return
> 0. But IMHO the comment in there is right. No ?
nope, you say that you should verify the new serial_struct, but you
don't verify anything, just return.
> >> +/*
> >> + * Configure/autoconfigure the port.
> >> + */
> >> +static void arc_serial_config_port(struct uart_port *port, int flags)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> >> +
> >> + if (flags & UART_CONFIG_TYPE &&
> >> + arc_serial_request_port(&uart->port) == 0)
> >> + uart->port.type = PORT_ARC;
> >> +}
> >> +
> >> +#if defined(CONFIG_CONSOLE_POLL) || defined(CONFIG_SERIAL_ARC_CONSOLE)
> >> +
> >> +static void arc_serial_poll_putchar(struct uart_port *port, unsigned char chr)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> >> +
> >> + while (!(UART_GET_STATUS(uart) & TXEMPTY))
> >> + cpu_relax();
> >> +
> >> + UART_SET_DATA(uart, chr);
> >> +}
> >> +#endif
> >> +
> >> +#ifdef CONFIG_CONSOLE_POLL
> >> +static int arc_serial_poll_getchar(struct uart_port *port)
> >> +{
> >> + struct arc_uart_port *uart = (struct arc_uart_port *)port;
> >> + unsigned char chr;
> >> +
> >> + while (!(UART_GET_STATUS(uart) & RXEMPTY))
> >> + cpu_relax();
> >> +
> >> + chr = UART_GET_DATA(uart);
> >> + return chr;
> >> +}
> >> +#endif
> >> +
> >> +static struct uart_ops arc_serial_pops = {
> >> + .tx_empty = arc_serial_tx_empty,
> >> + .set_mctrl = arc_serial_set_mctrl,
> >> + .get_mctrl = arc_serial_get_mctrl,
> >> + .stop_tx = arc_serial_stop_tx,
> >> + .start_tx = arc_serial_start_tx,
> >> + .stop_rx = arc_serial_stop_rx,
> >> + .enable_ms = arc_serial_enable_ms,
> >> + .break_ctl = arc_serial_break_ctl,
> >> + .startup = arc_serial_startup,
> >> + .shutdown = arc_serial_shutdown,
> >> + .set_termios = arc_serial_set_termios,
> >> + .type = arc_serial_type,
> >> + .release_port = arc_serial_release_port,
> >> + .request_port = arc_serial_request_port,
> >> + .config_port = arc_serial_config_port,
> >> + .verify_port = arc_serial_verify_port,
> >> +#ifdef CONFIG_CONSOLE_POLL
> >> + .poll_put_char = arc_serial_poll_putchar,
> >> + .poll_get_char = arc_serial_poll_getchar,
> >> +#endif
> >> +};
> >> +
> >> +static int __devinit
> >> +arc_uart_init_one(struct platform_device *pdev, struct arc_uart_port *uart)
> >> +{
> >> + struct resource *res, *res2;
> >> + unsigned long *plat_data;
> >> +
> >> + if (pdev->id < 0 || pdev->id >= CONFIG_SERIAL_ARC_NR_PORTS) {
> >> + dev_err(&pdev->dev, "Wrong uart platform device id.\n");
> >> + return -ENOENT;
> >> + }
> >> +
> >> + plat_data = ((unsigned long *)(pdev->dev.platform_data));
> >> + uart->baud = plat_data[0];
> >> +
> >> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >> + if (!res)
> >> + return -ENODEV;
> >> +
> >> + res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> >> + if (!res2)
> >> + return -ENODEV;
> >> +
> >> + uart->port.mapbase = res->start;
> >> + uart->port.membase = ioremap_nocache(res->start, resource_size(res));
> >> + if (!uart->port.membase)
> >> + /* No point of pr_err since UART itself is hosed here */
> >> + return -ENXIO;
> >> +
> >> + uart->port.irq = res2->start;
> >> + uart->port.dev = &pdev->dev;
> >> + uart->port.iotype = UPIO_MEM;
> >> + uart->port.flags = UPF_BOOT_AUTOCONF;
> >> + uart->port.line = pdev->id;
> >> + uart->port.ops = &arc_serial_pops;
> >> +
> >> + uart->port.uartclk = plat_data[1];
> >> + uart->port.fifosize = ARC_UART_TX_FIFO_SIZE;
> >> +
> >> + /*
> >> + * uart_insert_char( ) uses it in decideding whether to ignore a
> >> + * char or not. Explicitly setting it here, removes the subtelty
> >> + */
> >> + uart->port.ignore_status_mask = 0;
> >> +
> >> + /* Real Hardware vs. emulated to work around a bug */
> >> + uart->is_emulated = !!plat_data[2];
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
> >> +
> >> +static int __devinit arc_serial_console_setup(struct console *co, char *options)
> >> +{
> >> + struct uart_port *port;
> >> + int baud = 115200;
> >> + int bits = 8;
> >> + int parity = 'n';
> >> + int flow = 'n';
> >> +
> >> + if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)
> >> + return -ENODEV;
> >> +
> >> + /*
> >> + * The uart port backing the console (e.g. ttyARC1) might not have been
> >> + * init yet. If so, defer the console setup to after the port.
> >> + */
> >> + port = &arc_uart_ports[co->index].port;
> >> + if (!port->membase)
> >> + return -ENODEV;
> >> +
> >> + if (options)
> >> + uart_parse_options(options, &baud, &parity, &bits, &flow);
> >> +
> >> + /*
> >> + * Serial core will call port->ops->set_termios( )
> >> + * which will set the baud reg
> >> + */
> >> + return uart_set_options(port, co, baud, parity, bits, flow);
> >> +}
> >> +
> >> +static void arc_serial_console_putchar(struct uart_port *port, int ch)
> >> +{
> >> + arc_serial_poll_putchar(port, (unsigned char)ch);
> >> +}
> >> +
> >> +/*
> >> + * Interrupts are disabled on entering
> >> + */
> >> +static void arc_serial_console_write(struct console *co, const char *s,
> >> + unsigned int count)
> >> +{
> >> + struct uart_port *port = &arc_uart_ports[co->index].port;
> >> + unsigned long flags;
> >> +
> >> + spin_lock_irqsave(&port->lock, flags);
> >> + uart_console_write(port, s, count, arc_serial_console_putchar);
> >> + spin_unlock_irqrestore(&port->lock, flags);
> >> +}
> >> +
> >> +static struct console arc_console = {
> >> + .name = ARC_SERIAL_DEV_NAME,
> >> + .write = arc_serial_console_write,
> >> + .device = uart_console_device,
> >> + .setup = arc_serial_console_setup,
> >> + .flags = CON_PRINTBUFFER,
> >> + .index = -1,
> >> + .data = &arc_uart_driver
> >> +};
> >> +
> >> +static __init void early_serial_write(struct console *con, const char *s,
> >> + unsigned int n)
> >> +{
> >> + struct uart_port *port = &arc_uart_ports[con->index].port;
> >> + unsigned int i;
> >> +
> >> + for (i = 0; i < n; i++, s++) {
> >> + if (*s == '\n')
> >> + arc_serial_poll_putchar(port, '\r');
> >> + arc_serial_poll_putchar(port, *s);
> >> + }
> >> +}
> >> +
> >> +static struct __initdata console arc_early_serial_console = {
> >> + .name = "early_ARCuart",
> >> + .write = early_serial_write,
> >> + .flags = CON_PRINTBUFFER | CON_BOOT,
> >> + .index = -1
> >> +};
> >> +
> >> +static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
> >> +{
> >> + arc_early_serial_console.index = pdev->id;
> >> +
> >> + arc_uart_init_one(pdev, &arc_uart_ports[pdev->id]);
> >> +
> >> + arc_serial_console_setup(&arc_early_serial_console, NULL);
> >> +
> >> + register_console(&arc_early_serial_console);
> >> + return 0;
> >> +}
> >> +#else
> >> +static int __devinit arc_serial_probe_earlyprintk(struct platform_device *pdev)
> >> +{
> >> + return -ENODEV;
> >> +}
> >> +#endif /* CONFIG_SERIAL_ARC_CONSOLE */
> >> +
> >> +static int __devinit arc_serial_probe(struct platform_device *pdev)
> >> +{
> >> + struct arc_uart_port *uart;
> >> + int rc;
> >> +
> >> + if (is_early_platform_device(pdev))
> >> + return arc_serial_probe_earlyprintk(pdev);
> >> +
> >> + uart = &arc_uart_ports[pdev->id];
> >> + rc = arc_uart_init_one(pdev, uart);
> >> + if (rc)
> >> + return rc;
> >> +
> >> + return uart_add_one_port(&arc_uart_driver, &uart->port);
> >> +}
> >> +
> >> +static int __devexit arc_serial_remove(struct platform_device *pdev)
> >> +{
> >> + /* This will never be called */
> >> + return 0;
> >> +}
> >> +
> >> +static struct platform_driver arc_platform_driver = {
> >> + .probe = arc_serial_probe,
> >> + .remove = __devexit_p(arc_serial_remove),
> >> + .driver = {
> >> + .name = DRIVER_NAME,
> >> + .owner = THIS_MODULE,
> >> + },
> >> +};
> >> +
> >> +#ifdef CONFIG_SERIAL_ARC_CONSOLE
> >> +/*
> >> + * Register an early platform driver of "earlyprintk" class.
> >> + * ARCH platform code installs the driver and probes the early devices
> >> + * The installation could rely on user specifying earlyprintk=xyx in cmd line
> >> + * or it could be done independently, for all "earlyprintk" class drivers.
> >> + * [see arch/arc/plat-arcfpga/platform.c]
> >> + */
> >> +early_platform_init("earlyprintk", &arc_platform_driver);
> >> +
> >> +#endif /* CONFIG_SERIAL_ARC_CONSOLE */
> >> +
> >> +static int __init arc_serial_init(void)
> >> +{
> >> + int ret;
> >> +
> >> + pr_info("Serial: ARC serial driver: platform register\n");
> > please remove this line, it's just useless IMHO.
>
> It has helped me enough in past when debugging the uncoupling of driver
> from ARC platform code. I'd rather keep it !
then make it a debugging print ;-)
--
balbi
On Friday 26 October 2012 05:40 PM, Felipe Balbi wrote:
> On Fri, Oct 26, 2012 at 05:33:16PM +0530, [email protected] wrote:
>> +/*
>> + * Release the memory region(s) being used by 'port'.
>> + */
>> +static void arc_serial_release_port(struct uart_port *port)
>> +{
>> +}
>> +
>> +/*
>> + * Request the memory region(s) being used by 'port'.
>> + */
>> +static int arc_serial_request_port(struct uart_port *port)
>> +{
>> + return 0;
>> +}
>> +
>> +/*
>> + * Verify the new serial_struct (for TIOCSSERIAL).
>> + */
>> +static int
>> +arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
>> +{
>> + return 0;
>> +}
> why all these empty functions with wrong comments above them ??
Actually serial_core.c invokes the reqest/release callbacks w/o
verifying for a NULL pointer check. Thus they need to be in there even
if empty. I've removed the offending comments though !
-Vineet
On Sat, Oct 27, 2012 at 12:24:46PM +0530, Vineet Gupta wrote:
> On Friday 26 October 2012 05:40 PM, Felipe Balbi wrote:
> > On Fri, Oct 26, 2012 at 05:33:16PM +0530, [email protected] wrote:
> >> +/*
> >> + * Release the memory region(s) being used by 'port'.
> >> + */
> >> +static void arc_serial_release_port(struct uart_port *port)
> >> +{
> >> +}
> >> +
> >> +/*
> >> + * Request the memory region(s) being used by 'port'.
> >> + */
> >> +static int arc_serial_request_port(struct uart_port *port)
> >> +{
> >> + return 0;
> >> +}
> >> +
> >> +/*
> >> + * Verify the new serial_struct (for TIOCSSERIAL).
> >> + */
> >> +static int
> >> +arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
> >> +{
> >> + return 0;
> >> +}
> > why all these empty functions with wrong comments above them ??
>
> Actually serial_core.c invokes the reqest/release callbacks w/o
> verifying for a NULL pointer check. Thus they need to be in there even
> if empty. I've removed the offending comments though !
fair enough ;-)
--
balbi
I've already posted a v7 of the driver - with all your comments.
If you think it's ok - can you ACK it please !
TIA,
-Vineet
On Monday 29 October 2012 04:36 PM, Felipe Balbi wrote:
> On Sat, Oct 27, 2012 at 12:24:46PM +0530, Vineet Gupta wrote:
>> On Friday 26 October 2012 05:40 PM, Felipe Balbi wrote:
>>> On Fri, Oct 26, 2012 at 05:33:16PM +0530, [email protected] wrote:
>>>> +/*
>>>> + * Release the memory region(s) being used by 'port'.
>>>> + */
>>>> +static void arc_serial_release_port(struct uart_port *port)
>>>> +{
>>>> +}
>>>> +
>>>> +/*
>>>> + * Request the memory region(s) being used by 'port'.
>>>> + */
>>>> +static int arc_serial_request_port(struct uart_port *port)
>>>> +{
>>>> + return 0;
>>>> +}
>>>> +
>>>> +/*
>>>> + * Verify the new serial_struct (for TIOCSSERIAL).
>>>> + */
>>>> +static int
>>>> +arc_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
>>>> +{
>>>> + return 0;
>>>> +}
>>> why all these empty functions with wrong comments above them ??
>> Actually serial_core.c invokes the reqest/release callbacks w/o
>> verifying for a NULL pointer check. Thus they need to be in there even
>> if empty. I've removed the offending comments though !
> fair enough ;-)
>