Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753379AbbG3Od1 (ORCPT ); Thu, 30 Jul 2015 10:33:27 -0400 Received: from eusmtp01.atmel.com ([212.144.249.242]:44033 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751111AbbG3OdZ (ORCPT ); Thu, 30 Jul 2015 10:33:25 -0400 From: Cyrille Pitchen To: , , , , , CC: , , Cyrille Pitchen Subject: [PATCH linux-next 1/1] tty/serial: at91: fix I/O accesses on RHR and THR for AVR32 Date: Thu, 30 Jul 2015 16:33:38 +0200 Message-ID: X-Mailer: git-send-email 1.8.2.2 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5012 Lines: 145 This patch fixes I/O accesses on the Receiver Holding Register and on the Transmitter Holding Register. Indeed AVR32 can only perform 32bit I/O accesses on registers: using 8bit I/O accesses would read or write garbage data. Fixes: commit b5199d468177 ("tty/serial: at91: add support to FIFOs") Signed-off-by: Cyrille Pitchen --- Hi all, this patch fixes a bug on AVR32 introduced by the support of FIFOs for AT91. Indeed when FIFOs are enabled they work in Multiple Data mode. The Multiple Data mode allows to read up to 4 data from the Receiver Holding Register (RHR) or write up to 4 data into the Transmitter Holding Register (THR) in a single I/O access. Hence when only one data is to be read from the RHR or written into the THR, the driver cannot use 32bit I/O access anymore but must use 8bit I/O access instead. For ARM-base AT91 SoCs, 8bit I/O accesses can always be used even when FIFOs are not available. However AV32 can only use 32bit I/O accesses. Since atmel_uart_readb(), resp. atmel_uart_writeb(), was created by the FIFO support patch to access the RHR, resp. the THR, this patch replaces it by atmel_uart_read_char(), resp. atmel_uart_write_char(). Hence the actual width of the I/O access now depends only on the architecture. All registers but RHR and THR use 32bit I/O accesses. This patch was tested on a at91sam9260ek board. Best Regards, Cyrille ChangeLog: v1: initial version drivers/tty/serial/atmel_serial.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index e91b3b2f0590..5ca5cf3e9359 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -204,16 +204,33 @@ static inline void atmel_uart_writel(struct uart_port *port, u32 reg, u32 value) __raw_writel(value, port->membase + reg); } -static inline u8 atmel_uart_readb(struct uart_port *port, u32 reg) +#ifdef CONFIG_AVR32 + +/* AVR32 cannot handle 8 or 16bit I/O accesses but only 32bit I/O accesses */ +static inline u8 atmel_uart_read_char(struct uart_port *port) +{ + return __raw_readl(port->membase + ATMEL_US_RHR); +} + +static inline void atmel_uart_write_char(struct uart_port *port, u8 value) { - return __raw_readb(port->membase + reg); + __raw_writel(value, port->membase + ATMEL_US_THR); } -static inline void atmel_uart_writeb(struct uart_port *port, u32 reg, u8 value) +#else + +static inline u8 atmel_uart_read_char(struct uart_port *port) { - __raw_writeb(value, port->membase + reg); + return __raw_readb(port->membase + ATMEL_US_RHR); } +static inline void atmel_uart_write_char(struct uart_port *port, u8 value) +{ + __raw_writeb(value, port->membase + ATMEL_US_THR); +} + +#endif + #ifdef CONFIG_SERIAL_ATMEL_PDC static bool atmel_use_pdc_rx(struct uart_port *port) { @@ -658,7 +675,7 @@ static void atmel_rx_chars(struct uart_port *port) status = atmel_uart_readl(port, ATMEL_US_CSR); while (status & ATMEL_US_RXRDY) { - ch = atmel_uart_readb(port, ATMEL_US_RHR); + ch = atmel_uart_read_char(port); /* * note that the error handling code is @@ -709,7 +726,7 @@ static void atmel_tx_chars(struct uart_port *port) if (port->x_char && (atmel_uart_readl(port, ATMEL_US_CSR) & atmel_port->tx_done_mask)) { - atmel_uart_writeb(port, ATMEL_US_THR, port->x_char); + atmel_uart_write_char(port, port->x_char); port->icount.tx++; port->x_char = 0; } @@ -718,7 +735,7 @@ static void atmel_tx_chars(struct uart_port *port) while (atmel_uart_readl(port, ATMEL_US_CSR) & atmel_port->tx_done_mask) { - atmel_uart_writeb(port, ATMEL_US_THR, xmit->buf[xmit->tail]); + atmel_uart_write_char(port, xmit->buf[xmit->tail]); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); port->icount.tx++; if (uart_circ_empty(xmit)) @@ -2294,7 +2311,7 @@ static int atmel_poll_get_char(struct uart_port *port) while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_RXRDY)) cpu_relax(); - return atmel_uart_readb(port, ATMEL_US_RHR); + return atmel_uart_read_char(port); } static void atmel_poll_put_char(struct uart_port *port, unsigned char ch) @@ -2302,7 +2319,7 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch) while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY)) cpu_relax(); - atmel_uart_writeb(port, ATMEL_US_THR, ch); + atmel_uart_write_char(port, ch); } #endif @@ -2409,7 +2426,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch) { while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY)) cpu_relax(); - atmel_uart_writeb(port, ATMEL_US_THR, ch); + atmel_uart_write_char(port, ch); } /* -- 1.8.2.2 -- 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/