[PATCH] ppc32: m8xx watchdog update

This updates m8xx_wdt as follows:

1) Remove now obsolete fpos check in the write() function. The driver is
currently non functional due to this bug.

2) Use in/out macros for register access.

3) Allows m8xx_wdt to use a kernel timer instead of the builtin RTC/PIT
for keep-alive trigger (which is responsible for servicing the watchdog
until an userspace application takes over). For instance Cyclades PRxK
boards (MPC 855T based) have a non-functional internal RTC/PIT unit.
Behaviour for boards with RTC/PIT is unchaged.

4) The last change required moving the RTCSC register setting code
to a weak function which can be overriden by board specific files.
Otherwise the timer init code trashes the register making it impossible
for m8xx_wdt to detect the situation.

Signed-off-by: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/char/watchdog/mpc8xx_wdt.c b/drivers/char/watchdog/mpc8xx_wdt.c
index 56d62ba7c6ce..ac6fbace4724 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(void)
 {
         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(void)
 {
         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 inode *inode, struct file *file)
 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();