From f2d937f3bf00665ccf048b3b6616ef95859b0945 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Thu, 17 Apr 2008 20:05:37 +0200 Subject: consoles: polling support, kgdboc polled console handling support, to access a console in an irq-less way while in debug or irq context. absolutely zero impact as long as CONFIG_CONSOLE_POLL is disabled. (which is the default) [ jan.kiszka@siemens.com: lots of cleanups ] [ mingo@elte.hu: redesign, splitups, cleanups. ] Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar Signed-off-by: Jan Kiszka Reviewed-by: Thomas Gleixner --- drivers/serial/8250.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) (limited to 'drivers/serial/8250.c') diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index 77f7a7f0646..96a585e1cee 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -1740,6 +1740,60 @@ static inline void wait_for_xmitr(struct uart_8250_port *up, int bits) } } +#ifdef CONFIG_CONSOLE_POLL +/* + * Console polling routines for writing and reading from the uart while + * in an interrupt or debug context. + */ + +static int serial8250_get_poll_char(struct uart_port *port) +{ + struct uart_8250_port *up = (struct uart_8250_port *)port; + unsigned char lsr = serial_inp(up, UART_LSR); + + while (!(lsr & UART_LSR_DR)) + lsr = serial_inp(up, UART_LSR); + + return serial_inp(up, UART_RX); +} + + +static void serial8250_put_poll_char(struct uart_port *port, + unsigned char c) +{ + unsigned int ier; + struct uart_8250_port *up = (struct uart_8250_port *)port; + + /* + * First save the IER then disable the interrupts + */ + ier = serial_in(up, UART_IER); + if (up->capabilities & UART_CAP_UUE) + serial_out(up, UART_IER, UART_IER_UUE); + else + serial_out(up, UART_IER, 0); + + wait_for_xmitr(up, BOTH_EMPTY); + /* + * Send the character out. + * If a LF, also do CR... + */ + serial_out(up, UART_TX, c); + if (c == 10) { + wait_for_xmitr(up, BOTH_EMPTY); + serial_out(up, UART_TX, 13); + } + + /* + * Finally, wait for transmitter to become empty + * and restore the IER + */ + wait_for_xmitr(up, BOTH_EMPTY); + serial_out(up, UART_IER, ier); +} + +#endif /* CONFIG_CONSOLE_POLL */ + static int serial8250_startup(struct uart_port *port) { struct uart_8250_port *up = (struct uart_8250_port *)port; @@ -2386,6 +2440,10 @@ static struct uart_ops serial8250_pops = { .request_port = serial8250_request_port, .config_port = serial8250_config_port, .verify_port = serial8250_verify_port, +#ifdef CONFIG_CONSOLE_POLL + .poll_get_char = serial8250_get_poll_char, + .poll_put_char = serial8250_put_poll_char, +#endif }; static struct uart_8250_port serial8250_ports[UART_NR]; -- cgit v1.2.3