Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756249AbaJ2SPI (ORCPT ); Wed, 29 Oct 2014 14:15:08 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:34175 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755317AbaJ2SOm (ORCPT ); Wed, 29 Oct 2014 14:14:42 -0400 From: Stephen Boyd To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-serial@vger.kernel.org, Frank Rowand , Daniel Thompson Subject: [PATCH 2/2] tty: serial: msm: Support sysrq on uartDM devices Date: Wed, 29 Oct 2014 11:14:38 -0700 Message-Id: <1414606478-13709-3-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 2.1.0.61.ge50deb1 In-Reply-To: <1414606478-13709-1-git-send-email-sboyd@codeaurora.org> References: <1414606478-13709-1-git-send-email-sboyd@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To properly support sysrq on uartDM hardware we need to properly handle break characters. With the DM hardware the fifo can pack 4 characters at a time, where a break is indicated by an all zero byte. Unfortunately, we can't differentiate between an all zero byte for a break and an all zero byte of data, so try and do as best we can. First unmask the RX break start interrupt and record the interrupt when it arrives. Then while processing the fifo, detect the break by searching for an all zero character as long as we recently received an RX break start interrupt. This should make sysrq work fairly well. Cc: Frank Rowand Cc: Daniel Thompson Signed-off-by: Stephen Boyd --- drivers/tty/serial/msm_serial.c | 41 +++++++++++++++++++++++++++++++---------- drivers/tty/serial/msm_serial.h | 2 ++ 2 files changed, 33 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index cedcc36762a2..d44c04976f7a 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -54,6 +54,7 @@ struct msm_port { unsigned int imr; int is_uartdm; unsigned int old_snap_state; + bool break_detected; }; static inline void wait_for_xmitr(struct uart_port *port) @@ -126,23 +127,38 @@ static void handle_rx_dm(struct uart_port *port, unsigned int misr) while (count > 0) { unsigned char buf[4]; + int sysrq, r_count, i; sr = msm_read(port, UART_SR); if ((sr & UART_SR_RX_READY) == 0) { msm_port->old_snap_state -= count; break; } + ioread32_rep(port->membase + UARTDM_RF, buf, 1); - if (sr & UART_SR_RX_BREAK) { - port->icount.brk++; - if (uart_handle_break(port)) - continue; - } else if (sr & UART_SR_PAR_FRAME_ERR) - port->icount.frame++; + r_count = min_t(int, count, sizeof(buf)); + + for (i = 0; i < r_count; i++) { + char flag = TTY_NORMAL; - /* TODO: handle sysrq */ - tty_insert_flip_string(tport, buf, min(count, 4)); - count -= 4; + if (msm_port->break_detected && buf[i] == 0) { + port->icount.brk++; + flag = TTY_BREAK; + msm_port->break_detected = false; + if (uart_handle_break(port)) + continue; + } + + if (!(port->read_status_mask & UART_SR_RX_BREAK)) + flag = TTY_NORMAL; + + spin_unlock(&port->lock); + sysrq = uart_handle_sysrq_char(port, buf[i]); + spin_lock(&port->lock); + if (!sysrq) + tty_insert_flip_char(tport, buf[i], flag); + } + count -= r_count; } spin_unlock(&port->lock); @@ -291,6 +307,11 @@ static irqreturn_t msm_irq(int irq, void *dev_id) misr = msm_read(port, UART_MISR); msm_write(port, 0, UART_IMR); /* disable interrupt */ + if (misr & UART_IMR_RXBREAK_START) { + msm_port->break_detected = true; + msm_write(port, UART_CR_CMD_RESET_RXBREAK_START, UART_CR); + } + if (misr & (UART_IMR_RXLEV | UART_IMR_RXSTALE)) { if (msm_port->is_uartdm) handle_rx_dm(port, misr); @@ -496,7 +517,7 @@ static int msm_startup(struct uart_port *port) /* turn on RX and CTS interrupts */ msm_port->imr = UART_IMR_RXLEV | UART_IMR_RXSTALE | - UART_IMR_CURRENT_CTS; + UART_IMR_CURRENT_CTS | UART_IMR_RXBREAK_START; if (msm_port->is_uartdm) { msm_write(port, 0xFFFFFF, UARTDM_DMRX); diff --git a/drivers/tty/serial/msm_serial.h b/drivers/tty/serial/msm_serial.h index 73d3abe71e79..3e1c7138d8cd 100644 --- a/drivers/tty/serial/msm_serial.h +++ b/drivers/tty/serial/msm_serial.h @@ -65,6 +65,7 @@ #define UART_CR_TX_ENABLE (1 << 2) #define UART_CR_RX_DISABLE (1 << 1) #define UART_CR_RX_ENABLE (1 << 0) +#define UART_CR_CMD_RESET_RXBREAK_START ((1 << 11) | (2 << 4)) #define UART_IMR 0x0014 #define UART_IMR_TXLEV (1 << 0) @@ -72,6 +73,7 @@ #define UART_IMR_RXLEV (1 << 4) #define UART_IMR_DELTA_CTS (1 << 5) #define UART_IMR_CURRENT_CTS (1 << 6) +#define UART_IMR_RXBREAK_START (1 << 10) #define UART_IPR_RXSTALE_LAST 0x20 #define UART_IPR_STALE_LSB 0x1F -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/