Re: add bcm47xx watchdog driver
From: matthieu castet
Date: Fri Jun 05 2009 - 16:30:42 EST
Andrew Morton wrote:
On Thu, 04 Jun 2009 22:24:56 +0200
matthieu castet <castet.matthieu@xxxxxxx> wrote:
This add watchdog driver for broadcom 47xx device.
It uses the ssb subsytem to access embeded watchdog device.
Because the watchdog timeout is very short (about 2s), a soft timer is used
to increase the watchdog period.
Note : A patch for exporting the ssb_watchdog_timer_set will
be submitted on next linux-mips merge. Without this patch it can't
be build as a module.
...
--- linux-2.6.orig/drivers/watchdog/Kconfig 2009-05-25 22:22:02.000000000 +0200
+++ linux-2.6/drivers/watchdog/Kconfig 2009-05-25 22:26:06.000000000 +0200
@@ -764,6 +764,12 @@
help
Hardware driver for the built-in watchdog timer on TXx9 MIPS SoCs.
+config BCM47XX_WDT
+ tristate "Broadcom BCM47xx Watchdog Timer"
+ depends on BCM47XX
+ help
+ Hardware driver for the Broadcom BCM47xx Watchog Timer.
+
Please indent the kconfig body with a single tab character.
Done
...
+#define DRV_NAME "bcm47xx_wdt"
+
+#define WDT_DEFAULT_TIME 30 /* seconds */
+#define WDT_MAX_TIME 256 /* seconds */
+
+static int wdt_time = WDT_DEFAULT_TIME;
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+module_param(wdt_time, int, 0);
+MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
+ __MODULE_STRING(WDT_DEFAULT_TIME) ")");
+
+#ifdef CONFIG_WATCHDOG_NOWAYOUT
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout,
+ "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+#endif
hm, now what's happening with the third arg to module_param()?
I don't understand what you mean.
This thing is common in watchdog drivers. For example
drivers/watchdog/at91rm9200_wdt.c does the same thing.
+static struct platform_device *bcm47xx_wdt_platform_device;
+
+static unsigned long bcm47xx_wdt_busy;
+static char expect_release;
+static struct timer_list wdt_timer;
+static atomic_t ticks;
+
+static inline void bcm47xx_wdt_hw_start(void)
+{
+ /* this is 2,5s on 100Mhz clock and 2s on 133 Mhz */
+ ssb_watchdog_timer_set(&ssb_bcm47xx, 0xfffffff);
+}
+
+static inline int bcm47xx_wdt_hw_stop(void)
+{
+ return ssb_watchdog_timer_set(&ssb_bcm47xx, 0);
+}
+
+static void bcm47xx_timer_tick(unsigned long unused)
+{
+ if(!atomic_dec_and_test(&ticks)) {
Please pass this patch (and all others) through scripts/checkpatch.pl
and review the resulting output.
Done, everything is ok, expect a printk line over 80 characters.
+ bcm47xx_wdt_hw_start();
+ mod_timer(&wdt_timer, jiffies + HZ);
+ }
+ else {
+ printk(KERN_CRIT PFX "Watchdog will fire soon!!!.\n");
+ }
+}
+
+static inline void bcm47xx_wdt_pet(void)
+{
+ atomic_set(&ticks, wdt_time);
+}
What does "pet" stand for?
A watchdog timer is a computer hardware timing device that triggers a
system reset if the main program, due to some fault condition, such as a
hang, neglects to regularly service the watchdog (writing a “service
pulse” to it, also referred to as “petting the dog” [1]
[1] http://en.wikipedia.org/wiki/Watchdog_timer
But I can change the name if you want. Note that pet appear in
drivers/watchdog/sb_wdog.c and drivers/watchdog/sbc_epx_c3.c
+static void bcm47xx_wdt_start(void)
+{
+ bcm47xx_wdt_pet();
+ bcm47xx_timer_tick(0);
+}
+
+static void bcm47xx_wdt_pause(void)
+{
+ del_timer(&wdt_timer);
Should this be del_timer_sync()? The timer callback can still be
executing after del_timer() returns.
Yes, changed to del_timer_sync()
+static int bcm47xx_wdt_release(struct inode *inode, struct file *file)
+{
+ if (expect_release == 42) {
+ bcm47xx_wdt_stop();
+ } else {
+ printk(KERN_CRIT DRV_NAME ": Unexpected close, not stopping watchdog!\n");
Can this happen?
yes : this is a common pattern in watchdog driver (check for example
softdog) :
- expect_release is in bss (set to 0)
- we set expect_release to this magic value, only if we get a write with
a special character and we are not in nowayout.
- So for example doing a "cat /dev/watchdog" should go in this path.
+ bcm47xx_wdt_start();
+ }
+
+ clear_bit(0, &bcm47xx_wdt_busy);
+ expect_release = 0;
+ return 0;
+}
+
Thanks for the review.
I attach a new version.
This add watchdog driver for broadcom 47xx device.
It uses the ssb subsytem to access embeded watchdog device.
Because the watchdog timeout is very short (about 2s), a soft timer is used
to increase the watchdog period.
Note : A patch for exporting the ssb_watchdog_timer_set will
be submitted on next linux-mips merge. Without this patch it can't
be build as a module.
Signed-off-by: Aleksandar Radovanovic <biblbroks@xxxxxxxxxxx>
Signed-off-by: Matthieu CASTET <castet.matthieu@xxxxxxx>
Index: linux-2.6/drivers/watchdog/Kconfig
===================================================================
--- linux-2.6.orig/drivers/watchdog/Kconfig 2009-05-25 22:22:02.000000000 +0200
+++ linux-2.6/drivers/watchdog/Kconfig 2009-06-05 22:05:19.000000000 +0200
@@ -764,6 +764,12 @@
help
Hardware driver for the built-in watchdog timer on TXx9 MIPS SoCs.
+config BCM47XX_WDT
+ tristate "Broadcom BCM47xx Watchdog Timer"
+ depends on BCM47XX
+ help
+ Hardware driver for the Broadcom BCM47xx Watchog Timer.
+
# PARISC Architecture
# POWERPC Architecture
Index: linux-2.6/drivers/watchdog/Makefile
===================================================================
--- linux-2.6.orig/drivers/watchdog/Makefile 2009-05-25 22:22:02.000000000 +0200
+++ linux-2.6/drivers/watchdog/Makefile 2009-05-25 23:02:27.000000000 +0200
@@ -105,6 +105,7 @@
obj-$(CONFIG_SIBYTE_WDOG) += sb_wdog.o
obj-$(CONFIG_AR7_WDT) += ar7_wdt.o
obj-$(CONFIG_TXX9_WDT) += txx9wdt.o
+obj-$(CONFIG_BCM47XX_WDT) += bcm47xx_wdt.o
# PARISC Architecture
Index: linux-2.6/drivers/watchdog/bcm47xx_wdt.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/drivers/watchdog/bcm47xx_wdt.c 2009-06-05 22:25:37.000000000 +0200
@@ -0,0 +1,286 @@
+/*
+ * Watchdog driver for Broadcom BCM47XX
+ *
+ * Copyright (C) 2008 Aleksandar Radovanovic <biblbroks@xxxxxxxxxxx>
+ * Copyright (C) 2009 Matthieu CASTET <castet.matthieu@xxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/reboot.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+#include <linux/ssb/ssb_embedded.h>
+#include <asm/mach-bcm47xx/bcm47xx.h>
+
+#define DRV_NAME "bcm47xx_wdt"
+
+#define WDT_DEFAULT_TIME 30 /* seconds */
+#define WDT_MAX_TIME 256 /* seconds */
+
+static int wdt_time = WDT_DEFAULT_TIME;
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+module_param(wdt_time, int, 0);
+MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
+ __MODULE_STRING(WDT_DEFAULT_TIME) ")");
+
+#ifdef CONFIG_WATCHDOG_NOWAYOUT
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout,
+ "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+#endif
+
+static unsigned long bcm47xx_wdt_busy;
+static char expect_release;
+static struct timer_list wdt_timer;
+static atomic_t ticks;
+
+static inline void bcm47xx_wdt_hw_start(void)
+{
+ /* this is 2,5s on 100Mhz clock and 2s on 133 Mhz */
+ ssb_watchdog_timer_set(&ssb_bcm47xx, 0xfffffff);
+}
+
+static inline int bcm47xx_wdt_hw_stop(void)
+{
+ return ssb_watchdog_timer_set(&ssb_bcm47xx, 0);
+}
+
+static void bcm47xx_timer_tick(unsigned long unused)
+{
+ if (!atomic_dec_and_test(&ticks)) {
+ bcm47xx_wdt_hw_start();
+ mod_timer(&wdt_timer, jiffies + HZ);
+ } else {
+ printk(KERN_CRIT DRV_NAME "Watchdog will fire soon!!!\n");
+ }
+}
+
+static inline void bcm47xx_wdt_pet(void)
+{
+ atomic_set(&ticks, wdt_time);
+}
+
+static void bcm47xx_wdt_start(void)
+{
+ bcm47xx_wdt_pet();
+ bcm47xx_timer_tick(0);
+}
+
+static void bcm47xx_wdt_pause(void)
+{
+ del_timer_sync(&wdt_timer);
+ bcm47xx_wdt_hw_stop();
+}
+
+static void bcm47xx_wdt_stop(void)
+{
+ bcm47xx_wdt_pause();
+}
+
+static int bcm47xx_wdt_settimeout(int new_time)
+{
+ if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
+ return -EINVAL;
+
+ wdt_time = new_time;
+ return 0;
+}
+
+static int bcm47xx_wdt_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(0, &bcm47xx_wdt_busy))
+ return -EBUSY;
+
+ bcm47xx_wdt_start();
+ return nonseekable_open(inode, file);
+}
+
+static int bcm47xx_wdt_release(struct inode *inode, struct file *file)
+{
+ if (expect_release == 42) {
+ bcm47xx_wdt_stop();
+ } else {
+ printk(KERN_CRIT DRV_NAME
+ ": Unexpected close, not stopping watchdog!\n");
+ bcm47xx_wdt_start();
+ }
+
+ clear_bit(0, &bcm47xx_wdt_busy);
+ expect_release = 0;
+ return 0;
+}
+
+static ssize_t bcm47xx_wdt_write(struct file *file, const char __user *data,
+ size_t len, loff_t *ppos)
+{
+ if (len) {
+ if (!nowayout) {
+ size_t i;
+
+ expect_release = 0;
+
+ for (i = 0; i != len; i++) {
+ char c;
+ if (get_user(c, data + i))
+ return -EFAULT;
+ if (c == 'V')
+ expect_release = 42;
+ }
+ }
+ bcm47xx_wdt_pet();
+ }
+ return len;
+}
+
+static struct watchdog_info bcm47xx_wdt_info = {
+ .identity = DRV_NAME,
+ .options = WDIOF_SETTIMEOUT |
+ WDIOF_KEEPALIVEPING |
+ WDIOF_MAGICCLOSE,
+};
+
+static long bcm47xx_wdt_ioctl(struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ void __user *argp = (void __user *)arg;
+ int __user *p = argp;
+ int new_value, retval = -EINVAL;;
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ return copy_to_user(argp, &bcm47xx_wdt_info,
+ sizeof(bcm47xx_wdt_info)) ? -EFAULT : 0;
+
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(0, p);
+
+ case WDIOC_SETOPTIONS:
+ if (get_user(new_value, p))
+ return -EFAULT;
+
+ if (new_value & WDIOS_DISABLECARD) {
+ bcm47xx_wdt_stop();
+ retval = 0;
+ }
+
+ if (new_value & WDIOS_ENABLECARD) {
+ bcm47xx_wdt_start();
+ retval = 0;
+ }
+
+ return retval;
+
+ case WDIOC_KEEPALIVE:
+ bcm47xx_wdt_pet();
+ return 0;
+
+ case WDIOC_SETTIMEOUT:
+ if (get_user(new_value, p))
+ return -EFAULT;
+
+ if (bcm47xx_wdt_settimeout(new_value))
+ return -EINVAL;
+
+ bcm47xx_wdt_pet();
+
+ case WDIOC_GETTIMEOUT:
+ return put_user(wdt_time, p);
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+static int bcm47xx_wdt_notify_sys(struct notifier_block *this,
+ unsigned long code, void *unused)
+{
+ if (code == SYS_DOWN || code == SYS_HALT)
+ bcm47xx_wdt_stop();
+ return NOTIFY_DONE;
+}
+
+static const struct file_operations bcm47xx_wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .unlocked_ioctl = bcm47xx_wdt_ioctl,
+ .open = bcm47xx_wdt_open,
+ .release = bcm47xx_wdt_release,
+ .write = bcm47xx_wdt_write,
+};
+
+static struct miscdevice bcm47xx_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &bcm47xx_wdt_fops,
+};
+
+static struct notifier_block bcm47xx_wdt_notifier = {
+ .notifier_call = bcm47xx_wdt_notify_sys,
+};
+
+static int __init bcm47xx_wdt_init(void)
+{
+ int ret;
+
+ if (bcm47xx_wdt_hw_stop() < 0)
+ return -ENODEV;
+
+ setup_timer(&wdt_timer, bcm47xx_timer_tick, 0L);
+
+ if (bcm47xx_wdt_settimeout(wdt_time)) {
+ bcm47xx_wdt_settimeout(WDT_DEFAULT_TIME);
+ printk(KERN_INFO DRV_NAME
+ ": wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
+ wdt_time);
+ }
+
+ ret = register_reboot_notifier(&bcm47xx_wdt_notifier);
+ if (ret)
+ return ret;
+
+ ret = misc_register(&bcm47xx_wdt_miscdev);
+ if (ret) {
+ unregister_reboot_notifier(&bcm47xx_wdt_notifier);
+ return ret;
+ }
+
+ printk(KERN_INFO "BCM47xx Watchdog Timer enabled (%d seconds%s)\n",
+ wdt_time, nowayout ? ", nowayout" : "");
+ return 0;
+}
+
+static void __exit bcm47xx_wdt_exit(void)
+{
+ if (!nowayout)
+ bcm47xx_wdt_stop();
+
+ misc_deregister(&bcm47xx_wdt_miscdev);
+
+ unregister_reboot_notifier(&bcm47xx_wdt_notifier);
+}
+
+module_init(bcm47xx_wdt_init);
+module_exit(bcm47xx_wdt_exit);
+
+MODULE_AUTHOR("Aleksandar Radovanovic");
+MODULE_DESCRIPTION("Watchdog driver for Broadcom BCM47xx");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);