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/errno.h> 13#include <linux/fs.h> 14#include <linux/init.h> 15#include <linux/kernel.h> 16#include <linux/miscdevice.h> 17#include <linux/module.h> 18#include <linux/moduleparam.h> 19#include <linux/platform_device.h> 20#include <linux/types.h> 21#include <linux/watchdog.h> 22#include <asm/bitops.h> 23#include <asm/uaccess.h> 24#include <asm/arch/at91_st.h> 25 26 27#define WDT_DEFAULT_TIME 5 /* seconds */ 28#define WDT_MAX_TIME 256 /* seconds */ 29 30static int wdt_time = WDT_DEFAULT_TIME; 31static int nowayout = WATCHDOG_NOWAYOUT; 32 33module_param(wdt_time, int, 0); 34MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")"); 35 36#ifdef CONFIG_WATCHDOG_NOWAYOUT 37module_param(nowayout, int, 0); 38MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 39#endif 40 41 42static unsigned long at91wdt_busy; 43 44/* ......................................................................... */ 45 46/* 47 * Disable the watchdog. 48 */ 49static void inline at91_wdt_stop(void) 50{ 51 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN); 52} 53 54/* 55 * Enable and reset the watchdog. 56 */ 57static void inline at91_wdt_start(void) 58{ 59 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV)); 60 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST); 61} 62 63/* 64 * Reload the watchdog timer. (ie, pat the watchdog) 65 */ 66static void inline at91_wdt_reload(void) 67{ 68 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST); 69} 70 71/* ......................................................................... */ 72 73/* 74 * Watchdog device is opened, and watchdog starts running. 75 */ 76static int at91_wdt_open(struct inode *inode, struct file *file) 77{ 78 if (test_and_set_bit(0, &at91wdt_busy)) 79 return -EBUSY; 80 81 at91_wdt_start(); 82 return nonseekable_open(inode, file); 83} 84 85/* 86 * Close the watchdog device. 87 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also 88 * disabled. 89 */ 90static int at91_wdt_close(struct inode *inode, struct file *file) 91{ 92 if (!nowayout) 93 at91_wdt_stop(); /* Disable the watchdog when file is closed */ 94 95 clear_bit(0, &at91wdt_busy); 96 return 0; 97} 98 99/* 100 * Change the watchdog time interval. 101 */ 102static int at91_wdt_settimeout(int new_time) 103{ 104 /* 105 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz 106 * 107 * Since WDV is a 16-bit counter, the maximum period is 108 * 65536 / 0.256 = 256 seconds. 109 */ 110 if ((new_time <= 0) || (new_time > WDT_MAX_TIME)) 111 return -EINVAL; 112 113 /* Set new watchdog time. It will be used when at91_wdt_start() is called. */ 114 wdt_time = new_time; 115 return 0; 116} 117 118static struct watchdog_info at91_wdt_info = { 119 .identity = "at91 watchdog", 120 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 121}; 122 123/* 124 * Handle commands from user-space. 125 */ 126static int at91_wdt_ioctl(struct inode *inode, struct file *file, 127 unsigned int cmd, unsigned long arg) 128{ 129 void __user *argp = (void __user *)arg; 130 int __user *p = argp; 131 int new_value; 132 133 switch(cmd) { 134 case WDIOC_KEEPALIVE: 135 at91_wdt_reload(); /* pat the watchdog */ 136 return 0; 137 138 case WDIOC_GETSUPPORT: 139 return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0; 140 141 case WDIOC_SETTIMEOUT: 142 if (get_user(new_value, p)) 143 return -EFAULT; 144 145 if (at91_wdt_settimeout(new_value)) 146 return -EINVAL; 147 148 /* Enable new time value */ 149 at91_wdt_start(); 150 151 /* Return current value */ 152 return put_user(wdt_time, p); 153 154 case WDIOC_GETTIMEOUT: 155 return put_user(wdt_time, p); 156 157 case WDIOC_GETSTATUS: 158 case WDIOC_GETBOOTSTATUS: 159 return put_user(0, p); 160 161 case WDIOC_SETOPTIONS: 162 if (get_user(new_value, p)) 163 return -EFAULT; 164 165 if (new_value & WDIOS_DISABLECARD) 166 at91_wdt_stop(); 167 if (new_value & WDIOS_ENABLECARD) 168 at91_wdt_start(); 169 return 0; 170 171 default: 172 return -ENOTTY; 173 } 174} 175 176/* 177 * Pat the watchdog whenever device is written to. 178 */ 179static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos) 180{ 181 at91_wdt_reload(); /* pat the watchdog */ 182 return len; 183} 184 185/* ......................................................................... */ 186 187static const struct file_operations at91wdt_fops = { 188 .owner = THIS_MODULE, 189 .llseek = no_llseek, 190 .ioctl = at91_wdt_ioctl, 191 .open = at91_wdt_open, 192 .release = at91_wdt_close, 193 .write = at91_wdt_write, 194}; 195 196static struct miscdevice at91wdt_miscdev = { 197 .minor = WATCHDOG_MINOR, 198 .name = "watchdog", 199 .fops = &at91wdt_fops, 200}; 201 202static int __init at91wdt_probe(struct platform_device *pdev) 203{ 204 int res; 205 206 if (at91wdt_miscdev.parent) 207 return -EBUSY; 208 at91wdt_miscdev.parent = &pdev->dev; 209 210 res = misc_register(&at91wdt_miscdev); 211 if (res) 212 return res; 213 214 printk("AT91 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : ""); 215 return 0; 216} 217 218static int __exit at91wdt_remove(struct platform_device *pdev) 219{ 220 int res; 221 222 res = misc_deregister(&at91wdt_miscdev); 223 if (!res) 224 at91wdt_miscdev.parent = NULL; 225 226 return res; 227} 228 229static void at91wdt_shutdown(struct platform_device *pdev) 230{ 231 at91_wdt_stop(); 232} 233 234#ifdef CONFIG_PM 235 236static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message) 237{ 238 at91_wdt_stop(); 239 return 0; 240} 241 242static int at91wdt_resume(struct platform_device *pdev) 243{ 244 if (at91wdt_busy) 245 at91_wdt_start(); 246 return 0; 247} 248 249#else 250#define at91wdt_suspend NULL 251#define at91wdt_resume NULL 252#endif 253 254static struct platform_driver at91wdt_driver = { 255 .probe = at91wdt_probe, 256 .remove = __exit_p(at91wdt_remove), 257 .shutdown = at91wdt_shutdown, 258 .suspend = at91wdt_suspend, 259 .resume = at91wdt_resume, 260 .driver = { 261 .name = "at91_wdt", 262 .owner = THIS_MODULE, 263 }, 264}; 265 266static int __init at91_wdt_init(void) 267{ 268 /* Check that the heartbeat value is within range; if not reset to the default */ 269 if (at91_wdt_settimeout(wdt_time)) { 270 at91_wdt_settimeout(WDT_DEFAULT_TIME); 271 pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time); 272 } 273 274 return platform_driver_register(&at91wdt_driver); 275} 276 277static void __exit at91_wdt_exit(void) 278{ 279 platform_driver_unregister(&at91wdt_driver); 280} 281 282module_init(at91_wdt_init); 283module_exit(at91_wdt_exit); 284 285MODULE_AUTHOR("Andrew Victor"); 286MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200"); 287MODULE_LICENSE("GPL"); 288MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 289