diff options
Diffstat (limited to 'drivers/watchdog/at91sam9_wdt.c')
| -rw-r--r-- | drivers/watchdog/at91sam9_wdt.c | 328 |
1 files changed, 328 insertions, 0 deletions
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c new file mode 100644 index 00000000000..b4babfc3158 --- /dev/null +++ b/drivers/watchdog/at91sam9_wdt.c @@ -0,0 +1,328 @@ +/* + * Watchdog driver for Atmel AT91SAM9x processors. + * + * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.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. + */ + +/* + * The Watchdog Timer Mode Register can be only written to once. If the + * timeout need to be set from Linux, be sure that the bootstrap or the + * bootloader doesn't write to this register. + */ + +#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/platform_device.h> +#include <linux/types.h> +#include <linux/watchdog.h> +#include <linux/jiffies.h> +#include <linux/timer.h> +#include <linux/bitops.h> +#include <linux/uaccess.h> + +#include <asm/arch/at91_wdt.h> + +#define DRV_NAME "AT91SAM9 Watchdog" + +/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz, + * use this to convert a watchdog + * value from/to milliseconds. + */ +#define ms_to_ticks(t) (((t << 8) / 1000) - 1) +#define ticks_to_ms(t) (((t + 1) * 1000) >> 8) + +/* Hardware timeout in seconds */ +#define WDT_HW_TIMEOUT 2 + +/* Timer heartbeat (500ms) */ +#define WDT_TIMEOUT (HZ/2) + +/* User land timeout */ +#define WDT_HEARTBEAT 15 +static int heartbeat = WDT_HEARTBEAT; +module_param(heartbeat, int, 0); +MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. " + "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")"); + +static int nowayout = WATCHDOG_NOWAYOUT; +module_param(nowayout, int, 0); +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " + "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); + +static void at91_ping(unsigned long data); + +static struct { + unsigned long next_heartbeat; /* the next_heartbeat for the timer */ + unsigned long open; + char expect_close; + struct timer_list timer; /* The timer that pings the watchdog */ +} at91wdt_private; + +/* ......................................................................... */ + + +/* + * Reload the watchdog timer. (ie, pat the watchdog) + */ +static inline void at91_wdt_reset(void) +{ + at91_sys_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT); +} + +/* + * Timer tick + */ +static void at91_ping(unsigned long data) +{ + if (time_before(jiffies, at91wdt_private.next_heartbeat) || + (!nowayout && !at91wdt_private.open)) { + at91_wdt_reset(); + mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); + } else + printk(KERN_CRIT DRV_NAME": I will reset your machine !\n"); +} + +/* + * 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_private.open)) + return -EBUSY; + + at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; + mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); + + return nonseekable_open(inode, file); +} + +/* + * Close the watchdog device. + */ +static int at91_wdt_close(struct inode *inode, struct file *file) +{ + clear_bit(0, &at91wdt_private.open); + + /* stop internal ping */ + if (!at91wdt_private.expect_close) + del_timer(&at91wdt_private.timer); + + at91wdt_private.expect_close = 0; + return 0; +} + +/* + * Set the watchdog time interval in 1/256Hz (write-once) + * Counter is 12 bit. + */ +static int at91_wdt_settimeout(unsigned int timeout) +{ + unsigned int reg; + unsigned int mr; + + /* Check if disabled */ + mr = at91_sys_read(AT91_WDT_MR); + if (mr & AT91_WDT_WDDIS) { + printk(KERN_ERR DRV_NAME": sorry, watchdog is disabled\n"); + return -EIO; + } + + /* + * All counting occurs at SLOW_CLOCK / 128 = 256 Hz + * + * Since WDV is a 12-bit counter, the maximum period is + * 4096 / 256 = 16 seconds. + */ + reg = AT91_WDT_WDRSTEN /* causes watchdog reset */ + /* | AT91_WDT_WDRPROC causes processor reset only */ + | AT91_WDT_WDDBGHLT /* disabled in debug mode */ + | AT91_WDT_WDD /* restart at any time */ + | (timeout & AT91_WDT_WDV); /* timer value */ + at91_sys_write(AT91_WDT_MR, reg); + + return 0; +} + +static const struct watchdog_info at91_wdt_info = { + .identity = DRV_NAME, + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, +}; + +/* + * Handle commands from user-space. + */ +static long at91_wdt_ioctl(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_GETSUPPORT: + return copy_to_user(argp, &at91_wdt_info, + sizeof(at91_wdt_info)) ? -EFAULT : 0; + + case WDIOC_GETSTATUS: + case WDIOC_GETBOOTSTATUS: + return put_user(0, p); + + case WDIOC_KEEPALIVE: + at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; + return 0; + + case WDIOC_SETTIMEOUT: + if (get_user(new_value, p)) + return -EFAULT; + + heartbeat = new_value; + at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; + + return put_user(new_value, p); /* return current value */ + + case WDIOC_GETTIMEOUT: + return put_user(heartbeat, p); + } + return -ENOTTY; +} + +/* + * 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) +{ + if (!len) + return 0; + + /* Scan for magic character */ + if (!nowayout) { + size_t i; + + at91wdt_private.expect_close = 0; + + for (i = 0; i < len; i++) { + char c; + if (get_user(c, data + i)) + return -EFAULT; + if (c == 'V') { + at91wdt_private.expect_close = 42; + break; + } + } + } + + at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; + + return len; +} + +/* ......................................................................... */ + +static const struct file_operations at91wdt_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .unlocked_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 at91wdt_probe(struct platform_device *pdev) +{ + int res; + + if (at91wdt_miscdev.parent) + return -EBUSY; + at91wdt_miscdev.parent = &pdev->dev; + + /* Set watchdog */ + res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000)); + if (res) + return res; + + res = misc_register(&at91wdt_miscdev); + if (res) + return res; + + at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; + setup_timer(&at91wdt_private.timer, at91_ping, 0); + mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); + + printk(KERN_INFO DRV_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n", + heartbeat, nowayout); + + return 0; +} + +static int __exit at91wdt_remove(struct platform_device *pdev) +{ + int res; + + res = misc_deregister(&at91wdt_miscdev); + if (!res) + at91wdt_miscdev.parent = NULL; + + return res; +} + +#ifdef CONFIG_PM + +static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message) +{ + return 0; +} + +static int at91wdt_resume(struct platform_device *pdev) +{ + return 0; +} + +#else +#define at91wdt_suspend NULL +#define at91wdt_resume NULL +#endif + +static struct platform_driver at91wdt_driver = { + .remove = __exit_p(at91wdt_remove), + .suspend = at91wdt_suspend, + .resume = at91wdt_resume, + .driver = { + .name = "at91_wdt", + .owner = THIS_MODULE, + }, +}; + +static int __init at91sam_wdt_init(void) +{ + return platform_driver_probe(&at91wdt_driver, at91wdt_probe); +} + +static void __exit at91sam_wdt_exit(void) +{ + platform_driver_unregister(&at91wdt_driver); +} + +module_init(at91sam_wdt_init); +module_exit(at91sam_wdt_exit); + +MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>"); +MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |