1 /* Watchdog timer for the Geode GX/LX with the CS5535/CS5536 companion chip 2 * 3 * Copyright (C) 2006-2007, Advanced Micro Devices, Inc. 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 */ 10 11 12 #include <linux/module.h> 13 #include <linux/moduleparam.h> 14 #include <linux/types.h> 15 #include <linux/miscdevice.h> 16 #include <linux/watchdog.h> 17 #include <linux/fs.h> 18 #include <linux/platform_device.h> 19 #include <linux/reboot.h> 20 21 #include <asm/uaccess.h> 22 #include <asm/geode.h> 23 24 #define GEODEWDT_HZ 500 25 #define GEODEWDT_SCALE 6 26 #define GEODEWDT_MAX_SECONDS 131 27 28 #define WDT_FLAGS_OPEN 1 29 #define WDT_FLAGS_ORPHAN 2 30 31 #define DRV_NAME "geodewdt" 32 #define WATCHDOG_NAME "Geode GX/LX WDT" 33 #define WATCHDOG_TIMEOUT 60 34 35 static int timeout = WATCHDOG_TIMEOUT; 36 module_param(timeout, int, 0); 37 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. 1<= timeout <=131, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) "."); 38 39 static int nowayout = WATCHDOG_NOWAYOUT; 40 module_param(nowayout, int, 0); 41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 42 43 static struct platform_device *geodewdt_platform_device; 44 static unsigned long wdt_flags; 45 static int wdt_timer; 46 static int safe_close; 47 48 static void geodewdt_ping(void) 49 { 50 /* Stop the counter */ 51 geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 52 53 /* Reset the counter */ 54 geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 55 56 /* Enable the counter */ 57 geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); 58 } 59 60 static void geodewdt_disable(void) 61 { 62 geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 63 geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 64 } 65 66 static int geodewdt_set_heartbeat(int val) 67 { 68 if (val < 1 || val > GEODEWDT_MAX_SECONDS) 69 return -EINVAL; 70 71 geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 72 geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ); 73 geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 74 geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); 75 76 timeout = val; 77 return 0; 78 } 79 80 static int 81 geodewdt_open(struct inode *inode, struct file *file) 82 { 83 if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags)) 84 return -EBUSY; 85 86 if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags)) 87 __module_get(THIS_MODULE); 88 89 geodewdt_ping(); 90 return nonseekable_open(inode, file); 91 } 92 93 static int 94 geodewdt_release(struct inode *inode, struct file *file) 95 { 96 if (safe_close) { 97 geodewdt_disable(); 98 module_put(THIS_MODULE); 99 } 100 else { 101 printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n"); 102 geodewdt_ping(); 103 104 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags); 105 } 106 107 clear_bit(WDT_FLAGS_OPEN, &wdt_flags); 108 safe_close = 0; 109 return 0; 110 } 111 112 static ssize_t 113 geodewdt_write(struct file *file, const char __user *data, size_t len, 114 loff_t *ppos) 115 { 116 if(len) { 117 if (!nowayout) { 118 size_t i; 119 safe_close = 0; 120 121 for (i = 0; i != len; i++) { 122 char c; 123 124 if (get_user(c, data + i)) 125 return -EFAULT; 126 127 if (c == 'V') 128 safe_close = 1; 129 } 130 } 131 132 geodewdt_ping(); 133 } 134 return len; 135 } 136 137 static int 138 geodewdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 139 unsigned long arg) 140 { 141 void __user *argp = (void __user *)arg; 142 int __user *p = argp; 143 int interval; 144 145 static struct watchdog_info ident = { 146 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING 147 | WDIOF_MAGICCLOSE, 148 .firmware_version = 1, 149 .identity = WATCHDOG_NAME, 150 }; 151 152 switch(cmd) { 153 case WDIOC_GETSUPPORT: 154 return copy_to_user(argp, &ident, 155 sizeof(ident)) ? -EFAULT : 0; 156 break; 157 158 case WDIOC_GETSTATUS: 159 case WDIOC_GETBOOTSTATUS: 160 return put_user(0, p); 161 162 case WDIOC_KEEPALIVE: 163 geodewdt_ping(); 164 return 0; 165 166 case WDIOC_SETTIMEOUT: 167 if (get_user(interval, p)) 168 return -EFAULT; 169 170 if (geodewdt_set_heartbeat(interval)) 171 return -EINVAL; 172 173 /* Fall through */ 174 175 case WDIOC_GETTIMEOUT: 176 return put_user(timeout, p); 177 178 case WDIOC_SETOPTIONS: 179 { 180 int options, ret = -EINVAL; 181 182 if (get_user(options, p)) 183 return -EFAULT; 184 185 if (options & WDIOS_DISABLECARD) { 186 geodewdt_disable(); 187 ret = 0; 188 } 189 190 if (options & WDIOS_ENABLECARD) { 191 geodewdt_ping(); 192 ret = 0; 193 } 194 195 return ret; 196 } 197 default: 198 return -ENOTTY; 199 } 200 201 return 0; 202 } 203 204 static const struct file_operations geodewdt_fops = { 205 .owner = THIS_MODULE, 206 .llseek = no_llseek, 207 .write = geodewdt_write, 208 .ioctl = geodewdt_ioctl, 209 .open = geodewdt_open, 210 .release = geodewdt_release, 211 }; 212 213 static struct miscdevice geodewdt_miscdev = { 214 .minor = WATCHDOG_MINOR, 215 .name = "watchdog", 216 .fops = &geodewdt_fops 217 }; 218 219 static int __devinit 220 geodewdt_probe(struct platform_device *dev) 221 { 222 int ret, timer; 223 224 timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING); 225 226 if (timer == -1) { 227 printk(KERN_ERR "geodewdt: No timers were available\n"); 228 return -ENODEV; 229 } 230 231 wdt_timer = timer; 232 233 /* Set up the timer */ 234 235 geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 236 GEODEWDT_SCALE | (3 << 8)); 237 238 /* Set up comparator 2 to reset when the event fires */ 239 geode_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1); 240 241 /* Set up the initial timeout */ 242 243 geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, 244 timeout * GEODEWDT_HZ); 245 246 ret = misc_register(&geodewdt_miscdev); 247 248 return ret; 249 } 250 251 static int __devexit 252 geodewdt_remove(struct platform_device *dev) 253 { 254 misc_deregister(&geodewdt_miscdev); 255 return 0; 256 } 257 258 static void 259 geodewdt_shutdown(struct platform_device *dev) 260 { 261 geodewdt_disable(); 262 } 263 264 static struct platform_driver geodewdt_driver = { 265 .probe = geodewdt_probe, 266 .remove = __devexit_p(geodewdt_remove), 267 .shutdown = geodewdt_shutdown, 268 .driver = { 269 .owner = THIS_MODULE, 270 .name = DRV_NAME, 271 }, 272 }; 273 274 static int __init 275 geodewdt_init(void) 276 { 277 int ret; 278 279 ret = platform_driver_register(&geodewdt_driver); 280 if (ret) 281 return ret; 282 283 geodewdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0); 284 if (IS_ERR(geodewdt_platform_device)) { 285 ret = PTR_ERR(geodewdt_platform_device); 286 goto err; 287 } 288 289 return 0; 290 err: 291 platform_driver_unregister(&geodewdt_driver); 292 return ret; 293 } 294 295 static void __exit 296 geodewdt_exit(void) 297 { 298 platform_device_unregister(geodewdt_platform_device); 299 platform_driver_unregister(&geodewdt_driver); 300 } 301 302 module_init(geodewdt_init); 303 module_exit(geodewdt_exit); 304 305 MODULE_AUTHOR("Advanced Micro Devices, Inc"); 306 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver"); 307 MODULE_LICENSE("GPL"); 308 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 309