[PATCH] cirrus ep93xx watchdog driver

Add a driver for the on-chip watchdog on the cirrus ep93xx series of ARM
CPUs.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 257 insertions, 0 deletions

diff --git a/drivers/char/watchdog/ep93xx_wdt.c b/drivers/char/watchdog/ep93xx_wdt.c
new file mode 100644
index 000000000000..9021dbb78299
--- /dev/null
+++ b/drivers/char/watchdog/ep93xx_wdt.c
@@ -0,0 +1,257 @@
+/*
+ * Watchdog driver for Cirrus Logic EP93xx family of devices.
+ *
+ * Copyright (c) 2004 Ray Lehtiniemi
+ * Copyright (c) 2006 Tower Technologies
+ * Based on ep93xx driver, bits from alim7101_wdt.c
+ *
+ * Authors: Ray Lehtiniemi <rayl@mail.com>,
+ *      Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * This watchdog fires after 250msec, which is a too short interval
+ * for us to rely on the user space daemon alone. So we ping the
+ * wdt each ~200msec and eventually stop doing it if the user space
+ * daemon dies.
+ *
+ * TODO:
+ *
+ *      - Test last reset from watchdog status
+ *      - Add a few missing ioctls
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/timer.h>
+
+#include <asm/hardware.h>
+#include <asm/uaccess.h>
+
+#define WDT_VERSION     "0.3"
+#define PFX             "ep93xx_wdt: "
+
+/* default timeout (secs) */
+#define WDT_TIMEOUT 30
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+static int timeout = WDT_TIMEOUT;
+
+static struct timer_list timer;
+static unsigned long next_heartbeat;
+static unsigned long wdt_status;
+static unsigned long boot_status;
+
+#define WDT_IN_USE              0
+#define WDT_OK_TO_CLOSE         1
+
+#define EP93XX_WDT_REG(x)       (EP93XX_WATCHDOG_BASE + (x))
+#define EP93XX_WDT_WATCHDOG     EP93XX_WDT_REG(0x00)
+#define EP93XX_WDT_WDSTATUS     EP93XX_WDT_REG(0x04)
+
+/* reset the wdt every ~200ms */
+#define WDT_INTERVAL (HZ/5)
+
+static void wdt_enable(void)
+{
+        __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
+}
+
+static void wdt_disable(void)
+{
+        __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
+}
+
+static inline void wdt_ping(void)
+{
+        __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
+}
+
+static void wdt_startup(void)
+{
+        next_heartbeat = jiffies + (timeout * HZ);
+
+        wdt_enable();
+        mod_timer(&timer, jiffies + WDT_INTERVAL);
+}
+
+static void wdt_shutdown(void)
+{
+        del_timer_sync(&timer);
+        wdt_disable();
+}
+
+static void wdt_keepalive(void)
+{
+        /* user land ping */
+        next_heartbeat = jiffies + (timeout * HZ);
+}
+
+static int ep93xx_wdt_open(struct inode *inode, struct file *file)
+{
+        if (test_and_set_bit(WDT_IN_USE, &wdt_status))
+                return -EBUSY;
+
+        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+        wdt_startup();
+
+        return nonseekable_open(inode, file);
+}
+
+static ssize_t
+ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
+                 loff_t *ppos)
+{
+        /* Can't seek (pwrite) on this device */
+        if (*ppos != file->f_pos)
+                return -ESPIPE;
+
+        if (len) {
+                if (!nowayout) {
+                        size_t i;
+
+                        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+                        for (i = 0; i != len; i++) {
+                                char c;
+
+                                if (get_user(c, data + i))
+                                        return -EFAULT;
+
+                                if (c == 'V')
+                                        set_bit(WDT_OK_TO_CLOSE, &wdt_status);
+                                else
+                                        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+                        }
+                }
+                wdt_keepalive();
+        }
+
+        return len;
+}
+
+static struct watchdog_info ident = {
+        .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
+        .identity = "EP93xx Watchdog",
+};
+
+static int
+ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+                 unsigned long arg)
+{
+        int ret = -ENOIOCTLCMD;
+
+        switch (cmd) {
+        case WDIOC_GETSUPPORT:
+                ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
+                                sizeof(ident)) ? -EFAULT : 0;
+                break;
+
+        case WDIOC_GETSTATUS:
+                ret = put_user(0, (int __user *)arg);
+                break;
+
+        case WDIOC_GETBOOTSTATUS:
+                ret = put_user(boot_status, (int __user *)arg);
+                break;
+
+        case WDIOC_GETTIMEOUT:
+                /* actually, it is 0.250 seconds.... */
+                ret = put_user(1, (int __user *)arg);
+                break;
+
+        case WDIOC_KEEPALIVE:
+                wdt_keepalive();
+                ret = 0;
+                break;
+        }
+        return ret;
+}
+
+static int ep93xx_wdt_release(struct inode *inode, struct file *file)
+{
+        if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
+                wdt_shutdown();
+        else
+                printk(KERN_CRIT PFX "Device closed unexpectedly - "
+                        "timer will not stop\n");
+
+        clear_bit(WDT_IN_USE, &wdt_status);
+        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+        return 0;
+}
+
+static struct file_operations ep93xx_wdt_fops = {
+        .owner          = THIS_MODULE,
+        .write          = ep93xx_wdt_write,
+        .ioctl          = ep93xx_wdt_ioctl,
+        .open           = ep93xx_wdt_open,
+        .release        = ep93xx_wdt_release,
+};
+
+static struct miscdevice ep93xx_wdt_miscdev = {
+        .minor          = WATCHDOG_MINOR,
+        .name           = "watchdog",
+        .fops           = &ep93xx_wdt_fops,
+};
+
+static void ep93xx_timer_ping(unsigned long data)
+{
+        if (time_before(jiffies, next_heartbeat))
+                wdt_ping();
+
+        /* Re-set the timer interval */
+        mod_timer(&timer, jiffies + WDT_INTERVAL);
+}
+
+static int __init ep93xx_wdt_init(void)
+{
+        int err;
+
+        err = misc_register(&ep93xx_wdt_miscdev);
+
+        boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
+
+        printk(KERN_INFO PFX "EP93XX watchdog, driver version "
+                WDT_VERSION "%s\n",
+                (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
+                ? " (nCS1 disable detected)" : "");
+
+        if (timeout < 1 || timeout > 3600) {
+                timeout = WDT_TIMEOUT;
+                printk(KERN_INFO PFX
+                        "timeout value must be 1<=x<=3600, using %d\n",
+                        timeout);
+        }
+
+        setup_timer(&timer, ep93xx_timer_ping, 1);
+        return err;
+}
+
+static void __exit ep93xx_wdt_exit(void)
+{
+        wdt_shutdown();
+        misc_deregister(&ep93xx_wdt_miscdev);
+}
+
+module_init(ep93xx_wdt_init);
+module_exit(ep93xx_wdt_exit);
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
+
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
+                "Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("EP93xx Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(WDT_VERSION);
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);