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consoles: polling support, kgdboc

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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 <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Jason Wessel
2008-04-17 20:05:37 +02:00
committed by Ingo Molnar
parent dc7d552705
commit f2d937f3bf
8 changed files with 357 additions and 3 deletions
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58
drivers/serial/8250.c
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@@ -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];