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| author |   Lennert Buytenhek <buytenh@org.rmk.(none)> | 2005-06-20 18:51:07 +0100 |
|---|---|---|
| committer |   Russell King <rmk+kernel@arm.linux.org.uk> | 2005-06-20 18:51:07 +0100 |
| commit | e4fe19819ef32950541503042f32e71b67edffc7 (patch) | |
| tree | 57c68008ba8c3b3a9f6ab8950c620175e9405569 /drivers | |
| parent | [PATCH] ARM: 2693/1: Add PCI support for Versatile/PB (diff) | |
| download | linux-dev-e4fe19819ef32950541503042f32e71b67edffc7.tar.xz linux-dev-e4fe19819ef32950541503042f32e71b67edffc7.zip | |
[PATCH] ARM: 2701/1: free up ixp2000 timer 4 for the watchdog
Patch from Lennert Buytenhek
The IXP2000 has four timers, but if we're on an A-step IXP2800, timer
2 and 3 don't work. We need two timers for timekeeping (one for the
timer interrupt and one for tracking missed jiffies), so on early
IXP2800s we have no other choice but to use timer 1 and 4 for that,
but on all other IXP2000s we'd rather leave timer 4 free since that's
the only timer we can use for the watchdog.
So, on buggy IXP2000s (i.e. the A-step IXP2800) we use timer 4 for
tracking missed jiffies, and on all all non-buggy IXP2000s (i.e.
everything but the A-step IXP2800) we use timer 2.
On a pre-production IXP2800, this patch should print these messages
on boot:
Enabling IXP2800 erratum #25 workaround
Unable to use IXP2000 watchdog due to IXP2800 erratum #25
On any non-buggy IXP2800 (as well as on IXP2400s) you shouldn't see
anything at all, and the watchdog should be usable again.
Signed-off-by: Lennert Buytenhek
Signed-off-by: Deepak Saxena
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/char/watchdog/ixp2000_wdt.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/char/watchdog/ixp2000_wdt.c b/drivers/char/watchdog/ixp2000_wdt.c index ab659d37b4d2..4e98c215e5b1 100644 --- a/drivers/char/watchdog/ixp2000_wdt.c +++ b/drivers/char/watchdog/ixp2000_wdt.c @@ -192,7 +192,12 @@ static struct miscdevice ixp2000_wdt_miscdev = static int __init ixp2000_wdt_init(void) { - wdt_tick_rate = (*IXP2000_T1_CLD * HZ)/ 256;; + if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) { + printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n"); + return -EIO; + } + + wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256; return misc_register(&ixp2000_wdt_miscdev); } |