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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13 14#include <linux/bitops.h> 15#include <linux/errno.h> 16#include <linux/fs.h> 17#include <linux/init.h> 18#include <linux/io.h> 19#include <linux/kernel.h> 20#include <linux/miscdevice.h> 21#include <linux/module.h> 22#include <linux/moduleparam.h> 23#include <linux/platform_device.h> 24#include <linux/types.h> 25#include <linux/watchdog.h> 26#include <linux/uaccess.h> 27#include <linux/of.h> 28#include <linux/of_device.h> 29#include <mach/at91_st.h> 30 31#define WDT_DEFAULT_TIME 5 /* seconds */ 32#define WDT_MAX_TIME 256 /* seconds */ 33 34static int wdt_time = WDT_DEFAULT_TIME; 35static bool nowayout = WATCHDOG_NOWAYOUT; 36 37module_param(wdt_time, int, 0); 38MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default=" 39 __MODULE_STRING(WDT_DEFAULT_TIME) ")"); 40 41#ifdef CONFIG_WATCHDOG_NOWAYOUT 42module_param(nowayout, bool, 0); 43MODULE_PARM_DESC(nowayout, 44 "Watchdog cannot be stopped once started (default=" 45 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 46#endif 47 48 49static unsigned long at91wdt_busy; 50 51/* ......................................................................... */ 52 53/* 54 * Disable the watchdog. 55 */ 56static inline void at91_wdt_stop(void) 57{ 58 at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN); 59} 60 61/* 62 * Enable and reset the watchdog. 63 */ 64static inline void at91_wdt_start(void) 65{ 66 at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | 67 (((65536 * wdt_time) >> 8) & AT91_ST_WDV)); 68 at91_st_write(AT91_ST_CR, AT91_ST_WDRST); 69} 70 71/* 72 * Reload the watchdog timer. (ie, pat the watchdog) 73 */ 74static inline void at91_wdt_reload(void) 75{ 76 at91_st_write(AT91_ST_CR, AT91_ST_WDRST); 77} 78 79/* ......................................................................... */ 80 81/* 82 * Watchdog device is opened, and watchdog starts running. 83 */ 84static int at91_wdt_open(struct inode *inode, struct file *file) 85{ 86 if (test_and_set_bit(0, &at91wdt_busy)) 87 return -EBUSY; 88 89 at91_wdt_start(); 90 return nonseekable_open(inode, file); 91} 92 93/* 94 * Close the watchdog device. 95 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also 96 * disabled. 97 */ 98static int at91_wdt_close(struct inode *inode, struct file *file) 99{ 100 /* Disable the watchdog when file is closed */ 101 if (!nowayout) 102 at91_wdt_stop(); 103 104 clear_bit(0, &at91wdt_busy); 105 return 0; 106} 107 108/* 109 * Change the watchdog time interval. 110 */ 111static int at91_wdt_settimeout(int new_time) 112{ 113 /* 114 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz 115 * 116 * Since WDV is a 16-bit counter, the maximum period is 117 * 65536 / 256 = 256 seconds. 118 */ 119 if ((new_time <= 0) || (new_time > WDT_MAX_TIME)) 120 return -EINVAL; 121 122 /* Set new watchdog time. It will be used when 123 at91_wdt_start() is called. */ 124 wdt_time = new_time; 125 return 0; 126} 127 128static const struct watchdog_info at91_wdt_info = { 129 .identity = "at91 watchdog", 130 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 131}; 132 133/* 134 * Handle commands from user-space. 135 */ 136static long at91_wdt_ioctl(struct file *file, 137 unsigned int cmd, unsigned long arg) 138{ 139 void __user *argp = (void __user *)arg; 140 int __user *p = argp; 141 int new_value; 142 143 switch (cmd) { 144 case WDIOC_GETSUPPORT: 145 return copy_to_user(argp, &at91_wdt_info, 146 sizeof(at91_wdt_info)) ? -EFAULT : 0; 147 case WDIOC_GETSTATUS: 148 case WDIOC_GETBOOTSTATUS: 149 return put_user(0, p); 150 case WDIOC_SETOPTIONS: 151 if (get_user(new_value, p)) 152 return -EFAULT; 153 if (new_value & WDIOS_DISABLECARD) 154 at91_wdt_stop(); 155 if (new_value & WDIOS_ENABLECARD) 156 at91_wdt_start(); 157 return 0; 158 case WDIOC_KEEPALIVE: 159 at91_wdt_reload(); /* pat the watchdog */ 160 return 0; 161 case WDIOC_SETTIMEOUT: 162 if (get_user(new_value, p)) 163 return -EFAULT; 164 if (at91_wdt_settimeout(new_value)) 165 return -EINVAL; 166 /* Enable new time value */ 167 at91_wdt_start(); 168 /* Return current value */ 169 return put_user(wdt_time, p); 170 case WDIOC_GETTIMEOUT: 171 return put_user(wdt_time, p); 172 default: 173 return -ENOTTY; 174 } 175} 176 177/* 178 * Pat the watchdog whenever device is written to. 179 */ 180static ssize_t at91_wdt_write(struct file *file, const char *data, 181 size_t len, loff_t *ppos) 182{ 183 at91_wdt_reload(); /* pat the watchdog */ 184 return len; 185} 186 187/* ......................................................................... */ 188 189static const struct file_operations at91wdt_fops = { 190 .owner = THIS_MODULE, 191 .llseek = no_llseek, 192 .unlocked_ioctl = at91_wdt_ioctl, 193 .open = at91_wdt_open, 194 .release = at91_wdt_close, 195 .write = at91_wdt_write, 196}; 197 198static struct miscdevice at91wdt_miscdev = { 199 .minor = WATCHDOG_MINOR, 200 .name = "watchdog", 201 .fops = &at91wdt_fops, 202}; 203 204static int at91wdt_probe(struct platform_device *pdev) 205{ 206 int res; 207 208 if (at91wdt_miscdev.parent) 209 return -EBUSY; 210 at91wdt_miscdev.parent = &pdev->dev; 211 212 res = misc_register(&at91wdt_miscdev); 213 if (res) 214 return res; 215 216 pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n", 217 wdt_time, nowayout ? ", nowayout" : ""); 218 return 0; 219} 220 221static int at91wdt_remove(struct platform_device *pdev) 222{ 223 int res; 224 225 res = misc_deregister(&at91wdt_miscdev); 226 if (!res) 227 at91wdt_miscdev.parent = NULL; 228 229 return res; 230} 231 232static void at91wdt_shutdown(struct platform_device *pdev) 233{ 234 at91_wdt_stop(); 235} 236 237#ifdef CONFIG_PM 238 239static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message) 240{ 241 at91_wdt_stop(); 242 return 0; 243} 244 245static int at91wdt_resume(struct platform_device *pdev) 246{ 247 if (at91wdt_busy) 248 at91_wdt_start(); 249 return 0; 250} 251 252#else 253#define at91wdt_suspend NULL 254#define at91wdt_resume NULL 255#endif 256 257static const struct of_device_id at91_wdt_dt_ids[] = { 258 { .compatible = "atmel,at91rm9200-wdt" }, 259 { /* sentinel */ } 260}; 261MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids); 262 263static struct platform_driver at91wdt_driver = { 264 .probe = at91wdt_probe, 265 .remove = at91wdt_remove, 266 .shutdown = at91wdt_shutdown, 267 .suspend = at91wdt_suspend, 268 .resume = at91wdt_resume, 269 .driver = { 270 .name = "at91_wdt", 271 .owner = THIS_MODULE, 272 .of_match_table = at91_wdt_dt_ids, 273 }, 274}; 275 276static int __init at91_wdt_init(void) 277{ 278 /* Check that the heartbeat value is within range; 279 if not reset to the default */ 280 if (at91_wdt_settimeout(wdt_time)) { 281 at91_wdt_settimeout(WDT_DEFAULT_TIME); 282 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n", 283 wdt_time); 284 } 285 286 return platform_driver_register(&at91wdt_driver); 287} 288 289static void __exit at91_wdt_exit(void) 290{ 291 platform_driver_unregister(&at91wdt_driver); 292} 293 294module_init(at91_wdt_init); 295module_exit(at91_wdt_exit); 296 297MODULE_AUTHOR("Andrew Victor"); 298MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200"); 299MODULE_LICENSE("GPL"); 300MODULE_ALIAS("platform:at91_wdt"); 301