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authorAnton Vorontsov <avorontsov@ru.mvista.com>2008-07-03 23:51:36 -0700
committerWim Van Sebroeck <wim@iguana.be>2008-08-06 13:08:47 +0000
commit0d7b101404f7bedcf3f448c1667c3744551cd9ee (patch)
treeb38363e88e0b02c4bdbc265c05b3fb770fe0b143 /drivers/watchdog/mpc8xxx_wdt.c
parentcb55d282a0d2156e7d40ee81726ab16b569e96d7 (diff)
downloadlinux-0d7b101404f7bedcf3f448c1667c3744551cd9ee.tar.gz
[WATCHDOG] mpc8xxx_wdt: add support for MPC8xx watchdogs
The mpc8xxx_wdt driver is using two registers: SWSRR to push magic numbers, and SWCRR to control the watchdog. Both registers are available on the MPC8xx, and seem to have the same offsets and semantics as in MPC83xx/MPC86xx watchdogs. The only difference is prescale value. So this driver simply works on the MPC8xx CPUs. One quirk is needed for the MPC8xx, though. It has small prescale value and slow CPU, so the watchdog resets board prior to the driver has time to load. To solve this we should split initialization in two steps: start ping the watchdog early, and register the watchdog userspace interface later. MPC823 seem to be the first CPU in MPC8xx line, so we use fsl,mpc823-wdt compatible matching. Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Tested-by: Jochen Friedrich <jochen@scram.de> Cc: Kumar Gala <galak@kernel.crashing.org> Signed-off-by: Wim Van Sebroeck <wim@iguana.be> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/watchdog/mpc8xxx_wdt.c')
-rw-r--r--drivers/watchdog/mpc8xxx_wdt.c44
1 files changed, 33 insertions, 11 deletions
diff --git a/drivers/watchdog/mpc8xxx_wdt.c b/drivers/watchdog/mpc8xxx_wdt.c
index 3c5ed9e2622..f2094960e66 100644
--- a/drivers/watchdog/mpc8xxx_wdt.c
+++ b/drivers/watchdog/mpc8xxx_wdt.c
@@ -1,5 +1,5 @@
/*
- * mpc8xxx_wdt.c - MPC83xx/MPC86xx watchdog userspace interface
+ * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
*
* Authors: Dave Updegraff <dave@cray.org>
* Kumar Gala <galak@kernel.crashing.org>
@@ -207,13 +207,6 @@ static int __devinit mpc8xxx_wdt_probe(struct of_device *ofdev,
goto err_unmap;
}
- ret = misc_register(&mpc8xxx_wdt_miscdev);
- if (ret) {
- pr_err("cannot register miscdev on minor=%d (err=%d)\n",
- WATCHDOG_MINOR, ret);
- goto err_unmap;
- }
-
/* Calculate the timeout in seconds */
if (prescale)
timeout_sec = (timeout * wdt_type->prescaler) / freq;
@@ -234,6 +227,7 @@ static int __devinit mpc8xxx_wdt_probe(struct of_device *ofdev,
return 0;
err_unmap:
iounmap(wd_base);
+ wd_base = NULL;
return ret;
}
@@ -261,6 +255,12 @@ static const struct of_device_id mpc8xxx_wdt_match[] = {
.hw_enabled = true,
},
},
+ {
+ .compatible = "fsl,mpc823-wdt",
+ .data = &(struct mpc8xxx_wdt_type) {
+ .prescaler = 0x800,
+ },
+ },
{},
};
MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
@@ -275,20 +275,42 @@ static struct of_platform_driver mpc8xxx_wdt_driver = {
},
};
+/*
+ * We do wdt initialization in two steps: arch_initcall probes the wdt
+ * very early to start pinging the watchdog (misc devices are not yet
+ * available), and later module_init() just registers the misc device.
+ */
+static int __init mpc8xxx_wdt_init_late(void)
+{
+ int ret;
+
+ if (!wd_base)
+ return -ENODEV;
+
+ ret = misc_register(&mpc8xxx_wdt_miscdev);
+ if (ret) {
+ pr_err("cannot register miscdev on minor=%d (err=%d)\n",
+ WATCHDOG_MINOR, ret);
+ return ret;
+ }
+ return 0;
+}
+module_init(mpc8xxx_wdt_init_late);
+
static int __init mpc8xxx_wdt_init(void)
{
return of_register_platform_driver(&mpc8xxx_wdt_driver);
}
+arch_initcall(mpc8xxx_wdt_init);
static void __exit mpc8xxx_wdt_exit(void)
{
of_unregister_platform_driver(&mpc8xxx_wdt_driver);
}
-
-subsys_initcall(mpc8xxx_wdt_init);
module_exit(mpc8xxx_wdt_exit);
MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
-MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx/MPC86xx uProcessors");
+MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
+ "uProcessors");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);