Andrew Victor | 853807f | 2006-03-14 11:11:04 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Watchdog driver for Atmel AT91RM9200 (Thunder) |
| 3 | * |
| 4 | * Copyright (C) 2003 SAN People (Pty) Ltd |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public License |
| 8 | * as published by the Free Software Foundation; either version |
| 9 | * 2 of the License, or (at your option) any later version. |
| 10 | */ |
| 11 | |
| 12 | #include <linux/config.h> |
| 13 | #include <linux/errno.h> |
| 14 | #include <linux/fs.h> |
| 15 | #include <linux/init.h> |
| 16 | #include <linux/kernel.h> |
| 17 | #include <linux/miscdevice.h> |
| 18 | #include <linux/module.h> |
| 19 | #include <linux/moduleparam.h> |
| 20 | #include <linux/types.h> |
| 21 | #include <linux/watchdog.h> |
| 22 | #include <asm/bitops.h> |
| 23 | #include <asm/uaccess.h> |
| 24 | |
| 25 | |
| 26 | #define WDT_DEFAULT_TIME 5 /* 5 seconds */ |
| 27 | #define WDT_MAX_TIME 256 /* 256 seconds */ |
| 28 | |
| 29 | static int wdt_time = WDT_DEFAULT_TIME; |
| 30 | static int nowayout = WATCHDOG_NOWAYOUT; |
| 31 | |
| 32 | module_param(wdt_time, int, 0); |
| 33 | MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")"); |
| 34 | |
| 35 | module_param(nowayout, int, 0); |
| 36 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
| 37 | |
| 38 | |
| 39 | static unsigned long at91wdt_busy; |
| 40 | |
| 41 | /* ......................................................................... */ |
| 42 | |
| 43 | /* |
| 44 | * Disable the watchdog. |
| 45 | */ |
| 46 | static void inline at91_wdt_stop(void) |
| 47 | { |
| 48 | at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN); |
| 49 | } |
| 50 | |
| 51 | /* |
| 52 | * Enable and reset the watchdog. |
| 53 | */ |
| 54 | static void inline at91_wdt_start(void) |
| 55 | { |
| 56 | at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV)); |
| 57 | at91_sys_write(AT91_ST_CR, AT91_ST_WDRST); |
| 58 | } |
| 59 | |
| 60 | /* |
| 61 | * Reload the watchdog timer. (ie, pat the watchdog) |
| 62 | */ |
| 63 | static void inline at91_wdt_reload(void) |
| 64 | { |
| 65 | at91_sys_write(AT91_ST_CR, AT91_ST_WDRST); |
| 66 | } |
| 67 | |
| 68 | /* ......................................................................... */ |
| 69 | |
| 70 | /* |
| 71 | * Watchdog device is opened, and watchdog starts running. |
| 72 | */ |
| 73 | static int at91_wdt_open(struct inode *inode, struct file *file) |
| 74 | { |
| 75 | if (test_and_set_bit(0, &at91wdt_busy)) |
| 76 | return -EBUSY; |
| 77 | |
| 78 | at91_wdt_start(); |
| 79 | return nonseekable_open(inode, file); |
| 80 | } |
| 81 | |
| 82 | /* |
| 83 | * Close the watchdog device. |
| 84 | * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also |
| 85 | * disabled. |
| 86 | */ |
| 87 | static int at91_wdt_close(struct inode *inode, struct file *file) |
| 88 | { |
| 89 | if (!nowayout) |
| 90 | at91_wdt_stop(); /* Disable the watchdog when file is closed */ |
| 91 | |
| 92 | clear_bit(0, &at91wdt_busy); |
| 93 | return 0; |
| 94 | } |
| 95 | |
| 96 | /* |
| 97 | * Change the watchdog time interval. |
| 98 | */ |
| 99 | static int at91_wdt_settimeout(int new_time) |
| 100 | { |
| 101 | /* |
| 102 | * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz |
| 103 | * |
| 104 | * Since WDV is a 16-bit counter, the maximum period is |
| 105 | * 65536 / 0.256 = 256 seconds. |
| 106 | */ |
| 107 | if ((new_time <= 0) || (new_time > WDT_MAX_TIME)) |
| 108 | return -EINVAL; |
| 109 | |
| 110 | /* Set new watchdog time. It will be used when at91_wdt_start() is called. */ |
| 111 | wdt_time = new_time; |
| 112 | return 0; |
| 113 | } |
| 114 | |
| 115 | static struct watchdog_info at91_wdt_info = { |
| 116 | .identity = "at91 watchdog", |
| 117 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, |
| 118 | }; |
| 119 | |
| 120 | /* |
| 121 | * Handle commands from user-space. |
| 122 | */ |
| 123 | static int at91_wdt_ioctl(struct inode *inode, struct file *file, |
| 124 | unsigned int cmd, unsigned long arg) |
| 125 | { |
| 126 | void __user *argp = (void __user *)arg; |
| 127 | int __user *p = argp; |
| 128 | int new_value; |
| 129 | |
| 130 | switch(cmd) { |
| 131 | case WDIOC_KEEPALIVE: |
| 132 | at91_wdt_reload(); /* pat the watchdog */ |
| 133 | return 0; |
| 134 | |
| 135 | case WDIOC_GETSUPPORT: |
| 136 | return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0; |
| 137 | |
| 138 | case WDIOC_SETTIMEOUT: |
| 139 | if (get_user(new_value, p)) |
| 140 | return -EFAULT; |
| 141 | |
| 142 | if (at91_wdt_settimeout(new_value)) |
| 143 | return -EINVAL; |
| 144 | |
| 145 | /* Enable new time value */ |
| 146 | at91_wdt_start(); |
| 147 | |
| 148 | /* Return current value */ |
| 149 | return put_user(wdt_time, p); |
| 150 | |
| 151 | case WDIOC_GETTIMEOUT: |
| 152 | return put_user(wdt_time, p); |
| 153 | |
| 154 | case WDIOC_GETSTATUS: |
| 155 | case WDIOC_GETBOOTSTATUS: |
| 156 | return put_user(0, p); |
| 157 | |
| 158 | case WDIOC_SETOPTIONS: |
| 159 | if (get_user(new_value, p)) |
| 160 | return -EFAULT; |
| 161 | |
| 162 | if (new_value & WDIOS_DISABLECARD) |
| 163 | at91_wdt_stop(); |
| 164 | if (new_value & WDIOS_ENABLECARD) |
| 165 | at91_wdt_start(); |
| 166 | return 0; |
| 167 | |
| 168 | default: |
| 169 | return -ENOIOCTLCMD; |
| 170 | } |
| 171 | } |
| 172 | |
| 173 | /* |
| 174 | * Pat the watchdog whenever device is written to. |
| 175 | */ |
| 176 | static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos) |
| 177 | { |
| 178 | at91_wdt_reload(); /* pat the watchdog */ |
| 179 | return len; |
| 180 | } |
| 181 | |
| 182 | /* ......................................................................... */ |
| 183 | |
| 184 | static struct file_operations at91wdt_fops = { |
| 185 | .owner = THIS_MODULE, |
| 186 | .llseek = no_llseek, |
| 187 | .ioctl = at91_wdt_ioctl, |
| 188 | .open = at91_wdt_open, |
| 189 | .release = at91_wdt_close, |
| 190 | .write = at91_wdt_write, |
| 191 | }; |
| 192 | |
| 193 | static struct miscdevice at91wdt_miscdev = { |
| 194 | .minor = WATCHDOG_MINOR, |
| 195 | .name = "watchdog", |
| 196 | .fops = &at91wdt_fops, |
| 197 | }; |
| 198 | |
| 199 | static int __init at91_wdt_init(void) |
| 200 | { |
| 201 | int res; |
| 202 | |
| 203 | /* Check that the heartbeat value is within range; if not reset to the default */ |
| 204 | if (at91_wdt_settimeout(wdt_time)) { |
| 205 | at91_wdt_settimeout(WDT_DEFAULT_TIME); |
| 206 | printk(KERN_INFO "at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time); |
| 207 | } |
| 208 | |
| 209 | res = misc_register(&at91wdt_miscdev); |
| 210 | if (res) |
| 211 | return res; |
| 212 | |
| 213 | printk("AT91 Watchdog Timer enabled (%d seconds, nowayout=%d)\n", wdt_time, nowayout); |
| 214 | return 0; |
| 215 | } |
| 216 | |
| 217 | static void __exit at91_wdt_exit(void) |
| 218 | { |
| 219 | misc_deregister(&at91wdt_miscdev); |
| 220 | } |
| 221 | |
| 222 | module_init(at91_wdt_init); |
| 223 | module_exit(at91_wdt_exit); |
| 224 | |
| 225 | MODULE_AUTHOR("Andrew Victor"); |
| 226 | MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200"); |
| 227 | MODULE_LICENSE("GPL"); |
| 228 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |