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watchdog: it87_wdt: Work around non-working CIR interrupts 

On some hardware platforms, the it87_wdt watchdog resets the machine
despite the watchdog daemon running and writing to /dev/watchdog.

This is due to Consumer IR buffer underrun interrupts being used as
triggers to reset the timer.  On some buggy hardware implementations
such as the iEi AFL-12A-N270 single-board computer, this method does
not work.

However, resetting the timer by writing its original timeout value in
its configuration register over and over again suppresses the unwanted
reboots.

Add a module option (nocir), 0 by default in order not to break existing
setups.  Setting it to 1 enables the workaround.

Fixes bug #42801 <https://bugzilla.kernel.org/show_bug.cgi?id=42801>.
Tested primarily on Linux 3.5.7, applies cleanly on Linux 3.13.5.

Signed-off-by: Marc van der Wal <x0r+kernel@x0r.fr>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Marc van der Wal 2014-03-06 10:36:59 +01:00 committed by Wim Van Sebroeck
parent 5e82ec94ac
commit 0bcd0b6a47
2 changed files with 33 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/watchdog/watchdog-parameters.txt
View File

@ -150,6 +150,8 @@ nowayout: Disable watchdog shutdown on close
-------------------------------------------------
it87_wdt:
nogameport: Forbid the activation of game port, default=0
nocir: Forbid the use of CIR (workaround for some buggy setups); set to 1 if
system resets despite watchdog daemon running, default=0
exclusive: Watchdog exclusive device open, default=1
timeout: Watchdog timeout in seconds, default=60
testmode: Watchdog test mode (1 = no reboot), default=0

41
drivers/watchdog/it87_wdt.c
View File

@ -54,6 +54,7 @@
/* Defaults for Module Parameter */
#define DEFAULT_NOGAMEPORT 0
#define DEFAULT_NOCIR 0
#define DEFAULT_EXCLUSIVE 1
#define DEFAULT_TIMEOUT 60
#define DEFAULT_TESTMODE 0
@ -136,11 +137,13 @@
#define WDTS_LOCKED 3
#define WDTS_USE_GP 4
#define WDTS_EXPECTED 5
#define WDTS_USE_CIR 6
static unsigned int base, gpact, ciract, max_units, chip_type;
static unsigned long wdt_status;
static int nogameport = DEFAULT_NOGAMEPORT;
static int nocir = DEFAULT_NOCIR;
static int exclusive = DEFAULT_EXCLUSIVE;
static int timeout = DEFAULT_TIMEOUT;
static int testmode = DEFAULT_TESTMODE;
@ -149,6 +152,9 @@ static bool nowayout = DEFAULT_NOWAYOUT;
module_param(nogameport, int, 0);
MODULE_PARM_DESC(nogameport, "Forbid the activation of game port, default="
__MODULE_STRING(DEFAULT_NOGAMEPORT));
module_param(nocir, int, 0);
MODULE_PARM_DESC(nocir, "Forbid the use of Consumer IR interrupts to reset timer, default="
__MODULE_STRING(DEFAULT_NOCIR));
module_param(exclusive, int, 0);
MODULE_PARM_DESC(exclusive, "Watchdog exclusive device open, default="
__MODULE_STRING(DEFAULT_EXCLUSIVE));
@ -258,9 +264,17 @@ static void wdt_keepalive(void)
{
if (test_bit(WDTS_USE_GP, &wdt_status))
inb(base);
else
else if (test_bit(WDTS_USE_CIR, &wdt_status))
/* The timer reloads with around 5 msec delay */
outb(0x55, CIR_DR(base));
else {
if (superio_enter())
return;
superio_select(GPIO);
wdt_update_timeout();
superio_exit();
}
set_bit(WDTS_KEEPALIVE, &wdt_status);
}
@ -273,7 +287,7 @@ static int wdt_start(void)
superio_select(GPIO);
if (test_bit(WDTS_USE_GP, &wdt_status))
superio_outb(WDT_GAMEPORT, WDTCTRL);
else
else if (test_bit(WDTS_USE_CIR, &wdt_status))
superio_outb(WDT_CIRINT, WDTCTRL);
wdt_update_timeout();
@ -660,7 +674,7 @@ static int __init it87_wdt_init(void)
}
/* If we haven't Gameport support, try to get CIR support */
if (!test_bit(WDTS_USE_GP, &wdt_status)) {
if (!nocir && !test_bit(WDTS_USE_GP, &wdt_status)) {
if (!request_region(CIR_BASE, 8, WATCHDOG_NAME)) {
if (gp_rreq_fail)
pr_err("I/O Address 0x%04x and 0x%04x already in use\n",
@ -682,6 +696,7 @@ static int __init it87_wdt_init(void)
superio_select(GAMEPORT);
superio_outb(gpact, ACTREG);
}
set_bit(WDTS_USE_CIR, &wdt_status);
}
if (timeout < 1 || timeout > max_units * 60) {
@ -707,7 +722,7 @@ static int __init it87_wdt_init(void)
}
/* Initialize CIR to use it as keepalive source */
if (!test_bit(WDTS_USE_GP, &wdt_status)) {
if (test_bit(WDTS_USE_CIR, &wdt_status)) {
outb(0x00, CIR_RCR(base));
outb(0xc0, CIR_TCR1(base));
outb(0x5c, CIR_TCR2(base));
@ -717,9 +732,9 @@ static int __init it87_wdt_init(void)
outb(0x09, CIR_IER(base));
}
pr_info("Chip IT%04x revision %d initialized. timeout=%d sec (nowayout=%d testmode=%d exclusive=%d nogameport=%d)\n",
pr_info("Chip IT%04x revision %d initialized. timeout=%d sec (nowayout=%d testmode=%d exclusive=%d nogameport=%d nocir=%d)\n",
chip_type, chip_rev, timeout,
nowayout, testmode, exclusive, nogameport);
nowayout, testmode, exclusive, nogameport, nocir);
superio_exit();
return 0;
@ -727,8 +742,10 @@ static int __init it87_wdt_init(void)
err_out_reboot:
unregister_reboot_notifier(&wdt_notifier);
err_out_region:
release_region(base, test_bit(WDTS_USE_GP, &wdt_status) ? 1 : 8);
if (!test_bit(WDTS_USE_GP, &wdt_status)) {
if (test_bit(WDTS_USE_GP, &wdt_status))
release_region(base, 1);
else if (test_bit(WDTS_USE_CIR, &wdt_status)) {
release_region(base, 8);
superio_select(CIR);
superio_outb(ciract, ACTREG);
}
@ -754,7 +771,7 @@ static void __exit it87_wdt_exit(void)
if (test_bit(WDTS_USE_GP, &wdt_status)) {
superio_select(GAMEPORT);
superio_outb(gpact, ACTREG);
} else {
} else if (test_bit(WDTS_USE_CIR, &wdt_status)) {
superio_select(CIR);
superio_outb(ciract, ACTREG);
}
@ -763,7 +780,11 @@ static void __exit it87_wdt_exit(void)
misc_deregister(&wdt_miscdev);
unregister_reboot_notifier(&wdt_notifier);
release_region(base, test_bit(WDTS_USE_GP, &wdt_status) ? 1 : 8);
if (test_bit(WDTS_USE_GP, &wdt_status))
release_region(base, 1);
else if (test_bit(WDTS_USE_CIR, &wdt_status))
release_region(base, 8);
}
module_init(it87_wdt_init);