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kgdb,8250,pl011: Return immediately from console poll

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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: Jason Wessel <jason.wessel@windriver.com>
This commit is contained in:
Jason Wessel 2010-05-20 21:04:22 -05:00
parent dcc7871128
commit f5316b4aea
7 changed files with 50 additions and 11 deletions
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37
kernel/debug/gdbstub.c
View file

@ -30,6 +30,7 @@
#include <linux/kernel.h>
#include <linux/kgdb.h>
#include <linux/kdb.h>
#include <linux/reboot.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
@ -62,6 +63,30 @@ static int hex(char ch)
return -1;
}
#ifdef CONFIG_KGDB_KDB
static int gdbstub_read_wait(void)
{
int ret = -1;
int i;
/* poll any additional I/O interfaces that are defined */
while (ret < 0)
for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
ret = kdb_poll_funcs[i]();
if (ret > 0)
break;
}
return ret;
}
#else
static int gdbstub_read_wait(void)
{
int ret = dbg_io_ops->read_char();
while (ret == NO_POLL_CHAR)
ret = dbg_io_ops->read_char();
return ret;
}
#endif
/* scan for the sequence $<data>#<checksum> */
static void get_packet(char *buffer)
{
@ -75,7 +100,7 @@ static void get_packet(char *buffer)
* Spin and wait around for the start character, ignore all
* other characters:
*/
while ((ch = (dbg_io_ops->read_char())) != '$')
while ((ch = (gdbstub_read_wait())) != '$')
/* nothing */;
kgdb_connected = 1;
@ -88,7 +113,7 @@ static void get_packet(char *buffer)
* now, read until a # or end of buffer is found:
*/
while (count < (BUFMAX - 1)) {
ch = dbg_io_ops->read_char();
ch = gdbstub_read_wait();
if (ch == '#')
break;
checksum = checksum + ch;
@ -98,8 +123,8 @@ static void get_packet(char *buffer)
buffer[count] = 0;
if (ch == '#') {
xmitcsum = hex(dbg_io_ops->read_char()) << 4;
xmitcsum += hex(dbg_io_ops->read_char());
xmitcsum = hex(gdbstub_read_wait()) << 4;
xmitcsum += hex(gdbstub_read_wait());
if (checksum != xmitcsum)
/* failed checksum */
@ -144,10 +169,10 @@ static void put_packet(char *buffer)
dbg_io_ops->flush();
/* Now see what we get in reply. */
ch = dbg_io_ops->read_char();
ch = gdbstub_read_wait();
if (ch == 3)
ch = dbg_io_ops->read_char();
ch = gdbstub_read_wait();
/* If we get an ACK, we are done. */
if (ch == '+')