[PATCH] ppc32: Added support for the Book-E style Watchdog Timer

PowerPC 40x and Book-E processors support a watchdog timer at the processor
core level.  The timer has implementation dependent timeout frequencies
that can be configured by software.

One the first Watchdog timeout we get a critical exception.  It is left to
board specific code to determine what should happen at this point.  If
nothing is done and another timeout period expires the processor may
attempt to reset the machine.

Command line parameters:
  wdt=0 : disable watchdog (default)
  wdt=1 : enable watchdog

  wdt_period=N : N sets the value of the Watchdog Timer Period.

  The Watchdog Timer Period meaning is implementation specific. Check
  User Manual for the processor for more details.

This patch is based off of work done by Takeharu Kato.

Signed-off-by: Matt McClintock <msm@freescale.com>
Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

5 files changed, 54 insertions, 2 deletions

diff --git a/arch/ppc/kernel/head_44x.S b/arch/ppc/kernel/head_44x.S
index 69ff3a9961e..9e68e32edb6 100644
--- a/arch/ppc/kernel/head_44x.S
+++ b/arch/ppc/kernel/head_44x.S
@@ -462,7 +462,11 @@ interrupt_base:
 
 	/* Watchdog Timer Interrupt */
 	/* TODO: Add watchdog support */
+#ifdef CONFIG_BOOKE_WDT
+	CRITICAL_EXCEPTION(0x1020, WatchdogTimer, WatchdogException)
+#else
 	CRITICAL_EXCEPTION(0x1020, WatchdogTimer, UnknownException)
+#endif
 
 	/* Data TLB Error Interrupt */
 	START_EXCEPTION(DataTLBError)
diff --git a/arch/ppc/kernel/head_4xx.S b/arch/ppc/kernel/head_4xx.S
index 23fb51819ba..0a5e723d3be 100644
--- a/arch/ppc/kernel/head_4xx.S
+++ b/arch/ppc/kernel/head_4xx.S
@@ -448,7 +448,9 @@ label:
 
 /* 0x1020 - Watchdog Timer (WDT) Exception
 */
-
+#ifdef CONFIG_BOOKE_WDT
+	CRITICAL_EXCEPTION(0x1020, WDTException, WatchdogException)
+#else
 	CRITICAL_EXCEPTION(0x1020, WDTException, UnknownException)
 #endif
 
diff --git a/arch/ppc/kernel/head_fsl_booke.S b/arch/ppc/kernel/head_fsl_booke.S
index eb804b7a3cb..4028f4c7d97 100644
--- a/arch/ppc/kernel/head_fsl_booke.S
+++ b/arch/ppc/kernel/head_fsl_booke.S
@@ -564,8 +564,11 @@ interrupt_base:
 	EXCEPTION(0x3100, FixedIntervalTimer, UnknownException, EXC_XFER_EE)
 
 	/* Watchdog Timer Interrupt */
-	/* TODO: Add watchdog support */
+#ifdef CONFIG_BOOKE_WDT
+	CRITICAL_EXCEPTION(0x3200, WatchdogTimer, WatchdogException)
+#else
 	CRITICAL_EXCEPTION(0x3200, WatchdogTimer, UnknownException)
+#endif
 
 	/* Data TLB Error Interrupt */
 	START_EXCEPTION(DataTLBError)
diff --git a/arch/ppc/kernel/setup.c b/arch/ppc/kernel/setup.c
index 929e5d1cc7f..cf74a744e37 100644
--- a/arch/ppc/kernel/setup.c
+++ b/arch/ppc/kernel/setup.c
@@ -615,6 +615,30 @@ machine_init(unsigned long r3, unsigned long r4, unsigned long r5,
 	if (ppc_md.progress)
 		ppc_md.progress("id mach(): done", 0x200);
 }
+#ifdef CONFIG_BOOKE_WDT
+/* Checks wdt=x and wdt_period=xx command-line option */
+int __init early_parse_wdt(char *p)
+{
+	extern u32 wdt_enable;
+
+	if (p && strncmp(p, "0", 1) != 0)
+	       wdt_enable = 1;
+
+	return 0;
+}
+early_param("wdt", early_parse_wdt);
+
+int __init early_parse_wdt_period (char *p)
+{
+	extern u32 wdt_period;
+
+	if (p)
+		wdt_period = simple_strtoul(p, NULL, 0);
+
+	return 0;
+}
+early_param("wdt_period", early_parse_wdt_period);
+#endif	/* CONFIG_BOOKE_WDT */
 
 /* Checks "l2cr=xxxx" command-line option */
 int __init ppc_setup_l2cr(char *str)
diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
index 9e6ae569665..d87423d1003 100644
--- a/arch/ppc/kernel/traps.c
+++ b/arch/ppc/kernel/traps.c
@@ -904,6 +904,25 @@ void SPEFloatingPointException(struct pt_regs *regs)
 }
 #endif
 
+#ifdef CONFIG_BOOKE_WDT
+/*
+ * Default handler for a Watchdog exception,
+ * spins until a reboot occurs
+ */
+void __attribute__ ((weak)) WatchdogHandler(struct pt_regs *regs)
+{
+	/* Generic WatchdogHandler, implement your own */
+	mtspr(SPRN_TCR, mfspr(SPRN_TCR)&(~TCR_WIE));
+	return;
+}
+
+void WatchdogException(struct pt_regs *regs)
+{
+	printk (KERN_EMERG "PowerPC Book-E Watchdog Exception\n");
+	WatchdogHandler(regs);
+}
+#endif
+
 void __init trap_init(void)
 {
 }