On Thu, Nov 17, 2005 at 10:13:00AM +0100, Florian Schirmer wrote:
> Hi,
>
> okay here is what the current driver does:
>
> During startup it installs a timer irq (PIT) handler and sets the
> frequency to half of the watchdog timeout. As soon as this timer irq
> triggers we reset the watchdog inside the irq handler.
>
> If a userspace handler takes over the watchdog we deinstall the timer
> irq handler and let the userspace daemon handle the watchdog resets.
>
> Please not that we're talking about the timer irq, not the watchdog
> interrupt.
>
> I don't see why it should make a difference wether the watchdog
> generates a IRQ0/HRESET or a system reset directly since it should never
> trigger anyway.
>
> All the patch does is to use a kernel timer instead of the hardware
> timer. So i'm little confused.
Florian,
After your message I decided to check if the PIT is working, guess what: it
isnt.
Our board uses an external RTC (the internal RTC/PIT HW seem to be
nonexistant/nonfunctional).
I've changed the m8xx_wdt code to deal with that situation by checking
the RTC enable bit of RTCSC as follows:
m8xx_has_internal_rtc = in_be16(&imap->im_sit.sit_rtcsc) & RTCSC_RTE;
Problem with it is that the kernel sets the RTCSC_RTE bit
unconditionally in m8xx_calibrate_decr(), so you can't really know its
original value. The following patch changes m8xx_calibrate_decr()'s
RTC initialization to a weak function which can be overriden by board
specific code.
Dan, can you think of any nicer to avoid m8xx_calibrate_decr() from
overwriting RTCSC?
diff --git a/arch/ppc/syslib/m8xx_setup.c b/arch/ppc/syslib/m8xx_setup.c
index 1cc3abe..688616d 100644
--- a/arch/ppc/syslib/m8xx_setup.c
+++ b/arch/ppc/syslib/m8xx_setup.c
@@ -135,6 +135,16 @@ static struct irqaction tbint_irqaction
.name = "tbint",
};
+/* per-board overridable init_internal_rtc() function. */
+void __init __attribute__ ((weak))
+init_internal_rtc(void)
+{
+ /* Disable the RTC one second and alarm interrupts. */
+ out_be16(&((immap_t *)IMAP_ADDR)->im_sit.sit_rtcsc, in_be16(&((immap_t
*)IMAP_ADDR)->im_sit.sit_rtcsc) & ~(RTCSC_SIE | RTCSC_ALE));
+ /* Enable the RTC */
+ out_be16(&((immap_t *)IMAP_ADDR)->im_sit.sit_rtcsc, in_be16(&((immap_t
*)IMAP_ADDR)->im_sit.sit_rtcsc) | (RTCSC_RTF | RTCSC_RTE));
+}
+
/* The decrementer counts at the system (internal) clock frequency divided by
* sixteen, or external oscillator divided by four. We force the processor
* to use system clock divided by sixteen.
@@ -183,10 +193,7 @@ void __init m8xx_calibrate_decr(void)
out_be32(&((immap_t *)IMAP_ADDR)->im_sitk.sitk_rtcsck, KAPWR_KEY);
out_be32(&((immap_t *)IMAP_ADDR)->im_sitk.sitk_tbk, KAPWR_KEY);
- /* Disable the RTC one second and alarm interrupts. */
- out_be16(&((immap_t *)IMAP_ADDR)->im_sit.sit_rtcsc, in_be16(&((immap_t
*)IMAP_ADDR)->im_sit.sit_rtcsc) & ~(RTCSC_SIE | RTCSC_ALE));
- /* Enable the RTC */
- out_be16(&((immap_t *)IMAP_ADDR)->im_sit.sit_rtcsc, in_be16(&((immap_t
*)IMAP_ADDR)->im_sit.sit_rtcsc) | (RTCSC_RTF | RTCSC_RTE));
+ init_internal_rtc();
/* Enabling the decrementer also enables the timebase interrupts
* (or from the other point of view, to get decrementer interrupts
diff --git a/arch/ppc/syslib/m8xx_wdt.c b/arch/ppc/syslib/m8xx_wdt.c
index a21632d..df6c955 100644
--- a/arch/ppc/syslib/m8xx_wdt.c
+++ b/arch/ppc/syslib/m8xx_wdt.c
@@ -19,6 +19,7 @@
#include <syslib/m8xx_wdt.h>
static int wdt_timeout;
+int m8xx_has_internal_rtc = 0;
static irqreturn_t m8xx_wdt_interrupt(int, void *, struct pt_regs *);
static struct irqaction m8xx_wdt_irqaction = {
@@ -45,35 +46,15 @@ static irqreturn_t m8xx_wdt_interrupt(in
return IRQ_HANDLED;
}
-void __init m8xx_wdt_handler_install(bd_t * binfo)
+#define SYPCR_SWP 0x1
+#define SYPCR_SWE 0x4
+
+
+void __init m8xx_wdt_install_irq(volatile immap_t *imap, bd_t *binfo)
{
- volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
u32 pitc;
- u32 sypcr;
u32 pitrtclk;
- sypcr = in_be32(&imap->im_siu_conf.sc_sypcr);
-
- if (!(sypcr & 0x04)) {
- printk(KERN_NOTICE "m8xx_wdt: wdt disabled (SYPCR: 0x%08X)\n",
- sypcr);
- return;
- }
-
- m8xx_wdt_reset();
-
- printk(KERN_NOTICE
- "m8xx_wdt: active wdt found (SWTC: 0x%04X, SWP: 0x%01X)\n",
- (sypcr >> 16), sypcr & 0x01);
-
- wdt_timeout = (sypcr >> 16) & 0xFFFF;
-
- if (!wdt_timeout)
- wdt_timeout = 0xFFFF;
-
- if (sypcr & 0x01)
- wdt_timeout *= 2048;
-
/*
* Fire trigger if half of the wdt ticked down
*/
@@ -98,6 +79,67 @@ void __init m8xx_wdt_handler_install(bd_
printk(KERN_NOTICE
"m8xx_wdt: keep-alive trigger installed (PITC: 0x%04X)\n", pitc);
+}
+
+static void m8xx_wdt_timer_func(unsigned long data);
+
+static struct timer_list m8xx_wdt_timer =
+ TIMER_INITIALIZER(m8xx_wdt_timer_func, 0, 0);
+
+void m8xx_wdt_stop_timer(void)
+{
+ del_timer(&m8xx_wdt_timer);
+}
+
+void m8xx_wdt_install_timer(void)
+{
+ m8xx_wdt_timer.expires = jiffies + (HZ/2);
+ add_timer(&m8xx_wdt_timer);
+}
+
+static void m8xx_wdt_timer_func(unsigned long data)
+{
+ m8xx_wdt_reset();
+ m8xx_wdt_install_timer();
+}
+
+void __init m8xx_wdt_handler_install(bd_t * binfo)
+{
+ volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
+ u32 sypcr;
+
+ sypcr = in_be32(&imap->im_siu_conf.sc_sypcr);
+
+ if (!(sypcr & SYPCR_SWE)) {
+ printk(KERN_NOTICE "m8xx_wdt: wdt disabled (SYPCR: 0x%08X)\n",
+ sypcr);
+ return;
+ }
+
+ m8xx_wdt_reset();
+
+ printk(KERN_NOTICE
+ "m8xx_wdt: active wdt found (SWTC: 0x%04X, SWP: 0x%01X)\n",
+ (sypcr >> 16), sypcr & SYPCR_SWP);
+
+ wdt_timeout = (sypcr >> 16) & 0xFFFF;
+
+ if (!wdt_timeout)
+ wdt_timeout = 0xFFFF;
+
+ if (sypcr & SYPCR_SWP)
+ wdt_timeout *= 2048;
+
+ m8xx_has_internal_rtc = in_be16(&imap->im_sit.sit_rtcsc) & RTCSC_RTE;
+
+ /* if the internal RTC is off use a kernel timer */
+ if (!m8xx_has_internal_rtc) {
+ if (wdt_timeout < (binfo->bi_intfreq/HZ))
+ printk(KERN_ERR "m8xx_wdt: timeout too short for
ktimer!\n");
+ m8xx_wdt_install_timer();
+ } else
+ m8xx_wdt_install_irq(imap, binfo);
+
wdt_timeout /= binfo->bi_intfreq;
}
diff --git a/arch/ppc/syslib/m8xx_wdt.h b/arch/ppc/syslib/m8xx_wdt.h
index 0d81a9f..e75835f 100644
--- a/arch/ppc/syslib/m8xx_wdt.h
+++ b/arch/ppc/syslib/m8xx_wdt.h
@@ -9,8 +9,12 @@
#ifndef _PPC_SYSLIB_M8XX_WDT_H
#define _PPC_SYSLIB_M8XX_WDT_H
+extern int m8xx_has_internal_rtc;
+
extern void m8xx_wdt_handler_install(bd_t * binfo);
extern int m8xx_wdt_get_timeout(void);
extern void m8xx_wdt_reset(void);
+extern void m8xx_wdt_install_timer(void);
+extern void m8xx_wdt_stop_timer(void);
#endif /* _PPC_SYSLIB_M8XX_WDT_H */
diff --git a/drivers/char/watchdog/mpc8xx_wdt.c
b/drivers/char/watchdog/mpc8xx_wdt.c
index 56d62ba..ac6fbac 100644
--- a/drivers/char/watchdog/mpc8xx_wdt.c
+++ b/drivers/char/watchdog/mpc8xx_wdt.c
@@ -27,7 +27,10 @@ static void mpc8xx_wdt_handler_disable(v
{
volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
- imap->im_sit.sit_piscr &= ~(PISCR_PIE | PISCR_PTE);
+ if (!m8xx_has_internal_rtc)
+ m8xx_wdt_stop_timer();
+ else
+ out_be32(imap->im_sit.sit_piscr,
in_be32(&imap->im_sit.sit_piscr) & ~(PISCR_PIE | PISCR_PTE));
printk(KERN_NOTICE "mpc8xx_wdt: keep-alive handler deactivated\n");
}
@@ -36,7 +39,10 @@ static void mpc8xx_wdt_handler_enable(vo
{
volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
- imap->im_sit.sit_piscr |= PISCR_PIE | PISCR_PTE;
+ if (!m8xx_has_internal_rtc)
+ m8xx_wdt_install_timer();
+ else
+ out_be32(&imap->im_sit.sit_piscr,
in_be32(&imap->im_sit.sit_piscr) | PISCR_PIE | PISCR_PTE);
printk(KERN_NOTICE "mpc8xx_wdt: keep-alive handler activated\n");
}
@@ -68,9 +74,6 @@ static int mpc8xx_wdt_release(struct ino
static ssize_t mpc8xx_wdt_write(struct file *file, const char *data, size_t
len,
loff_t * ppos)
{
- if (ppos != &file->f_pos)
- return -ESPIPE;
-
if (len)
m8xx_wdt_reset();
