diff options
Diffstat (limited to 'drivers/watchdog/ep93xx_wdt.c')
| -rw-r--r-- | drivers/watchdog/ep93xx_wdt.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/drivers/watchdog/ep93xx_wdt.c b/drivers/watchdog/ep93xx_wdt.c new file mode 100644 index 00000000000..0e4787a0bb8 --- /dev/null +++ b/drivers/watchdog/ep93xx_wdt.c @@ -0,0 +1,253 @@ +/* + * 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) +{ + 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 = -ENOTTY; + + 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 const 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); |