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Commit f5316b4a authored by Jason Wessel's avatar Jason Wessel
Browse files

kgdb,8250,pl011: Return immediately from console poll 



The design of the kdb shell requires that every device that can
provide input to kdb have a polling routine that exits immediately if
there is no character available.  This is required in order to get the
page scrolling mechanism working.

Changing the kernel debugger I/O API to require all polling character
routines to exit immediately if there is no data allows the kernel
debugger to process multiple input channels.

NO_POLL_CHAR will be the return code to the polling routine when ever
there is no character available.

CC: linux-serial@vger.kernel.org
Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
parent dcc78711

drivers/serial/8250.c

+2 −2
Original line number Diff line number Diff line
@@ -1891,8 +1891,8 @@ 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);

	if (!(lsr & UART_LSR_DR))

		return NO_POLL_CHAR;



	return serial_inp(up, UART_RX);

}

drivers/serial/amba-pl011.c

+3 −3
Original line number Diff line number Diff line
@@ -342,9 +342,9 @@ static int pl010_get_poll_char(struct uart_port *port) 
	struct uart_amba_port *uap = (struct uart_amba_port *)port;

	unsigned int status;



	do {

	status = readw(uap->port.membase + UART01x_FR);

	} while (status & UART01x_FR_RXFE);

	if (status & UART01x_FR_RXFE)

		return NO_POLL_CHAR;



	return readw(uap->port.membase + UART01x_DR);

}

include/linux/kdb.h

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <asm/atomic.h>



#define KDB_POLL_FUNC_MAX	5

extern int kdb_poll_idx;



/*

 * kdb_initial_cpu is initialized to -1, and is set to the cpu

include/linux/serial_core.h

+1 −0
Original line number Diff line number Diff line
@@ -246,6 +246,7 @@ struct uart_ops { 
#endif

};



#define NO_POLL_CHAR		0x00ff0000

#define UART_CONFIG_TYPE	(1 << 0)

#define UART_CONFIG_IRQ		(1 << 1)

kernel/debug/debug_core.c

+2 −0
Original line number Diff line number Diff line
@@ -882,6 +882,8 @@ EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); 
int dbg_io_get_char(void)

{

	int ret = dbg_io_ops->read_char();

	if (ret == NO_POLL_CHAR)

		return -1;

	if (!dbg_kdb_mode)

		return ret;

	if (ret == 127)