[WATCHDOG] at91_wdt.c - Atmel AT91RM9200 watchdog driver

Watchdog driver for the Atmel AT91RM9200 processor.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@osdl.org>

drivers/char/watchdog/Kconfig

@@ -60,6 +60,13 @@ config SOFT_WATCHDOG
 
 # ARM Architecture
 
+config AT91_WATCHDOG
+	tristate "AT91RM9200 watchdog"
+	depends on WATCHDOG && ARCH_AT91RM9200
+	help
+	  Watchdog timer embedded into AT91RM9200 chips. This will reboot your
+	  system when the timeout is reached.
+
 config 21285_WATCHDOG
 	tristate "DC21285 watchdog"
 	depends on WATCHDOG && FOOTBRIDGE

drivers/char/watchdog/Makefile

@@ -23,6 +23,7 @@ obj-$(CONFIG_WDTPCI) += wdt_pci.o
 obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
 
 # ARM Architecture
+obj-$(CONFIG_AT91_WATCHDOG) += at91_wdt.o
 obj-$(CONFIG_21285_WATCHDOG) += wdt285.o
 obj-$(CONFIG_977_WATCHDOG) += wdt977.o
 obj-$(CONFIG_IXP2000_WATCHDOG) += ixp2000_wdt.o

drivers/char/watchdog/at91_wdt.c

@@ -0,0 +1,228 @@
+/*
+ * Watchdog driver for Atmel AT91RM9200 (Thunder)
+ *
+ *  Copyright (C) 2003 SAN People (Pty) Ltd
+ *
+ * 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/config.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/types.h>
+#include <linux/watchdog.h>
+#include <asm/bitops.h>
+#include <asm/uaccess.h>
+
+
+#define WDT_DEFAULT_TIME	5	/* 5 seconds */
+#define WDT_MAX_TIME		256	/* 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) ")");
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+
+static unsigned long at91wdt_busy;
+
+/* ......................................................................... */
+
+/*
+ * Disable the watchdog.
+ */
+static void inline at91_wdt_stop(void)
+{
+	at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
+}
+
+/*
+ * Enable and reset the watchdog.
+ */
+static void inline at91_wdt_start(void)
+{
+	at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
+	at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
+}
+
+/*
+ * Reload the watchdog timer.  (ie, pat the watchdog)
+ */
+static void inline at91_wdt_reload(void)
+{
+	at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
+}
+
+/* ......................................................................... */
+
+/*
+ * Watchdog device is opened, and watchdog starts running.
+ */
+static int at91_wdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(0, &at91wdt_busy))
+		return -EBUSY;
+
+	at91_wdt_start();
+	return nonseekable_open(inode, file);
+}
+
+/*
+ * Close the watchdog device.
+ * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
+ *  disabled.
+ */
+static int at91_wdt_close(struct inode *inode, struct file *file)
+{
+	if (!nowayout)
+		at91_wdt_stop();	/* Disable the watchdog when file is closed */
+
+	clear_bit(0, &at91wdt_busy);
+	return 0;
+}
+
+/*
+ * Change the watchdog time interval.
+ */
+static int at91_wdt_settimeout(int new_time)
+{
+	/*
+	 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
+	 *
+	 * Since WDV is a 16-bit counter, the maximum period is
+	 * 65536 / 0.256 = 256 seconds.
+	 */
+	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
+		return -EINVAL;
+
+	/* Set new watchdog time. It will be used when at91_wdt_start() is called. */
+	wdt_time = new_time;
+	return 0;
+}
+
+static struct watchdog_info at91_wdt_info = {
+	.identity	= "at91 watchdog",
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+};
+
+/*
+ * Handle commands from user-space.
+ */
+static int at91_wdt_ioctl(struct inode *inode, struct file *file,
+		unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	int new_value;
+
+	switch(cmd) {
+		case WDIOC_KEEPALIVE:
+			at91_wdt_reload();	/* pat the watchdog */
+			return 0;
+
+		case WDIOC_GETSUPPORT:
+			return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0;
+
+		case WDIOC_SETTIMEOUT:
+			if (get_user(new_value, p))
+				return -EFAULT;
+				
+			if (at91_wdt_settimeout(new_value))
+				return -EINVAL;
+
+			/* Enable new time value */
+			at91_wdt_start();
+
+			/* Return current value */
+			return put_user(wdt_time, p);
+
+		case WDIOC_GETTIMEOUT:
+			return put_user(wdt_time, p);
+
+		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)
+				at91_wdt_stop();
+			if (new_value & WDIOS_ENABLECARD)
+				at91_wdt_start();
+			return 0;
+
+		default:
+			return -ENOIOCTLCMD;
+	}
+}
+
+/*
+ * Pat the watchdog whenever device is written to.
+ */
+static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
+{
+	at91_wdt_reload();		/* pat the watchdog */
+	return len;
+}
+
+/* ......................................................................... */
+
+static struct file_operations at91wdt_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.ioctl		= at91_wdt_ioctl,
+	.open		= at91_wdt_open,
+	.release	= at91_wdt_close,
+	.write		= at91_wdt_write,
+};
+
+static struct miscdevice at91wdt_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &at91wdt_fops,
+};
+
+static int __init at91_wdt_init(void)
+{
+	int res;
+
+	/* Check that the heartbeat value is within range; if not reset to the default */
+	if (at91_wdt_settimeout(wdt_time)) {
+		at91_wdt_settimeout(WDT_DEFAULT_TIME);
+		printk(KERN_INFO "at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time);
+	}
+
+	res = misc_register(&at91wdt_miscdev);
+	if (res)
+		return res;
+
+	printk("AT91 Watchdog Timer enabled (%d seconds, nowayout=%d)\n", wdt_time, nowayout);
+	return 0;
+}
+
+static void __exit at91_wdt_exit(void)
+{
+	misc_deregister(&at91wdt_miscdev);
+}
+
+module_init(at91_wdt_init);
+module_exit(at91_wdt_exit);
+
+MODULE_AUTHOR("Andrew Victor");
+MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);