[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>

1 files changed, 228 insertions, 0 deletions

diff --git a/drivers/char/watchdog/at91_wdt.c b/drivers/char/watchdog/at91_wdt.c
new file mode 100644
index 000000000000..ac83bc4b019a
--- /dev/null
+++ b/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);