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 #include <linux/uaccess.h> 21 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 geodewdt_open(struct inode *inode, struct file *file) 81 { 82 if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags)) 83 return -EBUSY; 84 85 if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags)) 86 __module_get(THIS_MODULE); 87 88 geodewdt_ping(); 89 return nonseekable_open(inode, file); 90 } 91 92 static int geodewdt_release(struct inode *inode, struct file *file) 93 { 94 if (safe_close) { 95 geodewdt_disable(); 96 module_put(THIS_MODULE); 97 } else { 98 printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n"); 99 geodewdt_ping(); 100 101 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags); 102 } 103 104 clear_bit(WDT_FLAGS_OPEN, &wdt_flags); 105 safe_close = 0; 106 return 0; 107 } 108 109 static ssize_t geodewdt_write(struct file *file, const char __user *data, 110 size_t len, loff_t *ppos) 111 { 112 if (len) { 113 if (!nowayout) { 114 size_t i; 115 safe_close = 0; 116 117 for (i = 0; i != len; i++) { 118 char c; 119 120 if (get_user(c, data + i)) 121 return -EFAULT; 122 123 if (c == 'V') 124 safe_close = 1; 125 } 126 } 127 128 geodewdt_ping(); 129 } 130 return len; 131 } 132 133 static long geodewdt_ioctl(struct file *file, unsigned int cmd, 134 unsigned long arg) 135 { 136 void __user *argp = (void __user *)arg; 137 int __user *p = argp; 138 int interval; 139 140 static struct watchdog_info ident = { 141 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING 142 | WDIOF_MAGICCLOSE, 143 .firmware_version = 1, 144 .identity = WATCHDOG_NAME, 145 }; 146 147 switch (cmd) { 148 case WDIOC_GETSUPPORT: 149 return copy_to_user(argp, &ident, 150 sizeof(ident)) ? -EFAULT : 0; 151 break; 152 153 case WDIOC_GETSTATUS: 154 case WDIOC_GETBOOTSTATUS: 155 return put_user(0, p); 156 157 case WDIOC_SETOPTIONS: 158 { 159 int options, ret = -EINVAL; 160 161 if (get_user(options, p)) 162 return -EFAULT; 163 164 if (options & WDIOS_DISABLECARD) { 165 geodewdt_disable(); 166 ret = 0; 167 } 168 169 if (options & WDIOS_ENABLECARD) { 170 geodewdt_ping(); 171 ret = 0; 172 } 173 174 return ret; 175 } 176 case WDIOC_KEEPALIVE: 177 geodewdt_ping(); 178 return 0; 179 180 case WDIOC_SETTIMEOUT: 181 if (get_user(interval, p)) 182 return -EFAULT; 183 184 if (geodewdt_set_heartbeat(interval)) 185 return -EINVAL; 186 /* Fall through */ 187 case WDIOC_GETTIMEOUT: 188 return put_user(timeout, p); 189 190 default: 191 return -ENOTTY; 192 } 193 194 return 0; 195 } 196 197 static const struct file_operations geodewdt_fops = { 198 .owner = THIS_MODULE, 199 .llseek = no_llseek, 200 .write = geodewdt_write, 201 .unlocked_ioctl = geodewdt_ioctl, 202 .open = geodewdt_open, 203 .release = geodewdt_release, 204 }; 205 206 static struct miscdevice geodewdt_miscdev = { 207 .minor = WATCHDOG_MINOR, 208 .name = "watchdog", 209 .fops = &geodewdt_fops, 210 }; 211 212 static int __devinit geodewdt_probe(struct platform_device *dev) 213 { 214 int ret, timer; 215 216 timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING); 217 218 if (timer == -1) { 219 printk(KERN_ERR "geodewdt: No timers were available\n"); 220 return -ENODEV; 221 } 222 223 wdt_timer = timer; 224 225 /* Set up the timer */ 226 227 geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 228 GEODEWDT_SCALE | (3 << 8)); 229 230 /* Set up comparator 2 to reset when the event fires */ 231 geode_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1); 232 233 /* Set up the initial timeout */ 234 235 geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, 236 timeout * GEODEWDT_HZ); 237 238 ret = misc_register(&geodewdt_miscdev); 239 240 return ret; 241 } 242 243 static int __devexit geodewdt_remove(struct platform_device *dev) 244 { 245 misc_deregister(&geodewdt_miscdev); 246 return 0; 247 } 248 249 static void geodewdt_shutdown(struct platform_device *dev) 250 { 251 geodewdt_disable(); 252 } 253 254 static struct platform_driver geodewdt_driver = { 255 .probe = geodewdt_probe, 256 .remove = __devexit_p(geodewdt_remove), 257 .shutdown = geodewdt_shutdown, 258 .driver = { 259 .owner = THIS_MODULE, 260 .name = DRV_NAME, 261 }, 262 }; 263 264 static int __init geodewdt_init(void) 265 { 266 int ret; 267 268 ret = platform_driver_register(&geodewdt_driver); 269 if (ret) 270 return ret; 271 272 geodewdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0); 273 if (IS_ERR(geodewdt_platform_device)) { 274 ret = PTR_ERR(geodewdt_platform_device); 275 goto err; 276 } 277 278 return 0; 279 err: 280 platform_driver_unregister(&geodewdt_driver); 281 return ret; 282 } 283 284 static void __exit geodewdt_exit(void) 285 { 286 platform_device_unregister(geodewdt_platform_device); 287 platform_driver_unregister(&geodewdt_driver); 288 } 289 290 module_init(geodewdt_init); 291 module_exit(geodewdt_exit); 292 293 MODULE_AUTHOR("Advanced Micro Devices, Inc"); 294 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver"); 295 MODULE_LICENSE("GPL"); 296 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 297