diff options
Diffstat (limited to 'drivers/char/watchdog/at91_wdt.c')
| -rw-r--r-- | drivers/char/watchdog/at91_wdt.c | 228 |
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 00000000000..ac83bc4b019 --- /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); |