From 9e6077bd84a7bffa73b59d9704682aeab5781fa0 Mon Sep 17 00:00:00 2001 From: Haavard Skinnemoen Date: Sun, 15 Jul 2007 23:40:36 -0700 Subject: [PATCH] atmel_serial: fix break handling The RXBRK field in the AT91/AT32 USART status register has the following definition according to e.g. the AT32AP7000 data sheet: RXBRK: Break Received/End of Break 0: No Break received or End of Break detected since the last RSTSTA. 1: Break Received or End of Break detected since the last RSTSTA. Thus, for each break, the USART sets the RXBRK bit twice. This patch modifies the driver to report the break event to the serial core only once by keeping track of whether a break condition is currently active. The break_active flag is reset as soon as a character is received, so even if we miss the start-of-break interrupt this should do the right thing. Signed-off-by: Haavard Skinnemoen Cc: Andrew Victor Cc: Russell King Cc: Ivan Kuten Cc: Nicolas Ferre Cc: Patrice Vilchez Cc: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/serial/atmel_serial.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c index 3320bcd92c0a..4d6b3c56d20e 100644 --- a/drivers/serial/atmel_serial.c +++ b/drivers/serial/atmel_serial.c @@ -114,6 +114,7 @@ struct atmel_uart_port { struct uart_port uart; /* uart */ struct clk *clk; /* uart clock */ unsigned short suspended; /* is port suspended? */ + int break_active; /* break being received */ }; static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART]; @@ -252,6 +253,7 @@ static void atmel_break_ctl(struct uart_port *port, int break_state) */ static void atmel_rx_chars(struct uart_port *port) { + struct atmel_uart_port *atmel_port = (struct atmel_uart_port *) port; struct tty_struct *tty = port->info->tty; unsigned int status, ch, flg; @@ -267,13 +269,29 @@ static void atmel_rx_chars(struct uart_port *port) * note that the error handling code is * out of the main execution path */ - if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME | ATMEL_US_OVRE | ATMEL_US_RXBRK))) { + if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME + | ATMEL_US_OVRE | ATMEL_US_RXBRK) + || atmel_port->break_active)) { UART_PUT_CR(port, ATMEL_US_RSTSTA); /* clear error */ - if (status & ATMEL_US_RXBRK) { + if (status & ATMEL_US_RXBRK + && !atmel_port->break_active) { status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME); /* ignore side-effect */ port->icount.brk++; + atmel_port->break_active = 1; + UART_PUT_IER(port, ATMEL_US_RXBRK); if (uart_handle_break(port)) goto ignore_char; + } else { + /* + * This is either the end-of-break + * condition or we've received at + * least one character without RXBRK + * being set. In both cases, the next + * RXBRK will indicate start-of-break. + */ + UART_PUT_IDR(port, ATMEL_US_RXBRK); + status &= ~ATMEL_US_RXBRK; + atmel_port->break_active = 0; } if (status & ATMEL_US_PARE) port->icount.parity++; @@ -352,6 +370,16 @@ static irqreturn_t atmel_interrupt(int irq, void *dev_id) /* Interrupt receive */ if (pending & ATMEL_US_RXRDY) atmel_rx_chars(port); + else if (pending & ATMEL_US_RXBRK) { + /* + * End of break detected. If it came along + * with a character, atmel_rx_chars will + * handle it. + */ + UART_PUT_CR(port, ATMEL_US_RSTSTA); + UART_PUT_IDR(port, ATMEL_US_RXBRK); + atmel_port->break_active = 0; + } // TODO: All reads to CSR will clear these interrupts! if (pending & ATMEL_US_RIIC) port->icount.rng++; -- 2.20.1