Having WATCHDOG_RESET() called automatically from the timer interrupt
runs counter to the idea of a watchdog device - if the board runs into
an infinite loops with interrupts still enabled, the watchdog will
never fire.
When using CONFIG_(SPL_)WDT, the watchdog_reset function is a lot more
complicated than just poking a few SOC-specific registers - it
involves accessing all kinds of global data, and if the interrupt
happens at the wrong time (say, in the middle of an WATCHDOG_RESET()
call from ordinary code), that can end up corrupting said global data.
Allow the board to opt out of calling WATCHDOG_RESET() from the timer
interrupt handler by setting CONFIG_SYS_WATCHDOG_FREQ to 0 - as that
setting is currently nonsensical (it would be compile-time
divide-by-zero), it cannot affect any existing boards.
Add documentation for both the existing and extended meaning of
CONFIG_SYS_WATCHDOG_FREQ.
Signed-off-by: Rasmus Villemoes <rasmus.villem...@prevas.dk>
---
README | 9 +++++++++
arch/m68k/lib/time.c | 2 +-
arch/powerpc/lib/interrupts.c | 2 +-
drivers/timer/mpc83xx_timer.c | 2 +-
4 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/README b/README
index a565748e43..ad13092bbb 100644
--- a/README
+++ b/README
@@ -747,6 +747,15 @@ The following options need to be configured:
SoC, then define this variable and provide board
specific code for the "hw_watchdog_reset" function.
+ CONFIG_SYS_WATCHDOG_FREQ
+ Some platforms automatically call WATCHDOG_RESET()
+ from the timer interrupt handler every
+ CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
+ board configuration file, a default of CONFIG_SYS_HZ/2
+ (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
+ to 0 disables calling WATCHDOG_RESET() from the timer
+ interrupt.
+
- Real-Time Clock:
When CONFIG_CMD_DATE is selected, the type of the RTC
diff --git a/arch/m68k/lib/time.c b/arch/m68k/lib/time.c
index cbe29e72a8..ebb2ac54db 100644
--- a/arch/m68k/lib/time.c
+++ b/arch/m68k/lib/time.c
@@ -71,7 +71,7 @@ void dtimer_interrupt(void *not_used)
timestamp++;
#if defined(CONFIG_WATCHDOG) || defined (CONFIG_HW_WATCHDOG)
- if ((timestamp % (CONFIG_SYS_WATCHDOG_FREQ)) == 0) {
+ if (CONFIG_SYS_WATCHDOG_FREQ && (timestamp %
(CONFIG_SYS_WATCHDOG_FREQ)) == 0) {
WATCHDOG_RESET ();
}
#endif /* CONFIG_WATCHDOG || CONFIG_HW_WATCHDOG */
diff --git a/arch/powerpc/lib/interrupts.c b/arch/powerpc/lib/interrupts.c
index 73f270002c..5ba4cd0c13 100644
--- a/arch/powerpc/lib/interrupts.c
+++ b/arch/powerpc/lib/interrupts.c
@@ -80,7 +80,7 @@ void timer_interrupt(struct pt_regs *regs)
timestamp++;
#if defined(CONFIG_WATCHDOG) || defined (CONFIG_HW_WATCHDOG)
- if ((timestamp % (CONFIG_SYS_WATCHDOG_FREQ)) == 0)
+ if (CONFIG_SYS_WATCHDOG_FREQ && (timestamp %
(CONFIG_SYS_WATCHDOG_FREQ)) == 0)
WATCHDOG_RESET ();
#endif /* CONFIG_WATCHDOG || CONFIG_HW_WATCHDOG */
diff --git a/drivers/timer/mpc83xx_timer.c b/drivers/timer/mpc83xx_timer.c
index 9adb4b4cab..952293195f 100644
--- a/drivers/timer/mpc83xx_timer.c
+++ b/drivers/timer/mpc83xx_timer.c
@@ -175,7 +175,7 @@ void timer_interrupt(struct pt_regs *regs)
priv->timestamp++;
#if defined(CONFIG_WATCHDOG) || defined(CONFIG_HW_WATCHDOG)
- if ((priv->timestamp % (CONFIG_SYS_WATCHDOG_FREQ)) == 0)
+ if (CONFIG_SYS_WATCHDOG_FREQ && (priv->timestamp %
(CONFIG_SYS_WATCHDOG_FREQ)) == 0)
WATCHDOG_RESET();
#endif /* CONFIG_WATCHDOG || CONFIG_HW_WATCHDOG */
--
2.29.2
