[WATCHDOG] add bcm47xx watchdog driver

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@sezampro.rs>
Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Tested-by: Florian Fainelli <florian@openwrt.org>
Cc: Ralf Baechle <ralf@linux-mips.org>                                                                                       
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/watchdog/Kconfig

@@ -729,6 +729,12 @@ config SBC_EPX_C3_WATCHDOG
 
 # MIPS Architecture
 
+config BCM47XX_WDT
+	tristate "Broadcom BCM47xx Watchdog Timer"
+	depends on BCM47XX
+	help
+	  Hardware driver for the Broadcom BCM47xx Watchog Timer.
+
 config RC32434_WDT
 	tristate "IDT RC32434 SoC Watchdog Timer"
 	depends on MIKROTIK_RB532

drivers/watchdog/Makefile

@@ -101,6 +101,7 @@ obj-$(CONFIG_SBC_EPX_C3_WATCHDOG) += sbc_epx_c3.o
 # M68KNOMMU Architecture
 
 # MIPS Architecture
+obj-$(CONFIG_BCM47XX_WDT) += bcm47xx_wdt.o
 obj-$(CONFIG_RC32434_WDT) += rc32434_wdt.o
 obj-$(CONFIG_INDYDOG) += indydog.o
 obj-$(CONFIG_WDT_MTX1) += mtx-1_wdt.o

drivers/watchdog/bcm47xx_wdt.c

+/*
+ *  Watchdog driver for Broadcom BCM47XX
+ *
+ *  Copyright (C) 2008 Aleksandar Radovanovic <biblbroks@sezampro.rs>
+ *  Copyright (C) 2009 Matthieu CASTET <castet.matthieu@free.fr>
+ *
+ *  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		255	/* 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 0 < wdt_time < %d, using %d\n",
+			(WDT_MAX_TIME + 1), 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);