1 /* Watchdog timer for machines with the CS5535/CS5536 companion chip 2 * 3 * Copyright (C) 2006-2007, Advanced Micro Devices, Inc. 4 * Copyright (C) 2009 Andres Salomon <dilinger@collabora.co.uk> 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/module.h> 15 #include <linux/moduleparam.h> 16 #include <linux/types.h> 17 #include <linux/miscdevice.h> 18 #include <linux/watchdog.h> 19 #include <linux/fs.h> 20 #include <linux/platform_device.h> 21 #include <linux/reboot.h> 22 #include <linux/uaccess.h> 23 24 #include <linux/cs5535.h> 25 26 #define GEODEWDT_HZ 500 27 #define GEODEWDT_SCALE 6 28 #define GEODEWDT_MAX_SECONDS 131 29 30 #define WDT_FLAGS_OPEN 1 31 #define WDT_FLAGS_ORPHAN 2 32 33 #define DRV_NAME "geodewdt" 34 #define WATCHDOG_NAME "Geode GX/LX WDT" 35 #define WATCHDOG_TIMEOUT 60 36 37 static int timeout = WATCHDOG_TIMEOUT; 38 module_param(timeout, int, 0); 39 MODULE_PARM_DESC(timeout, 40 "Watchdog timeout in seconds. 1<= timeout <=131, default=" 41 __MODULE_STRING(WATCHDOG_TIMEOUT) "."); 42 43 static bool nowayout = WATCHDOG_NOWAYOUT; 44 module_param(nowayout, bool, 0); 45 MODULE_PARM_DESC(nowayout, 46 "Watchdog cannot be stopped once started (default=" 47 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 48 49 static struct platform_device *geodewdt_platform_device; 50 static unsigned long wdt_flags; 51 static struct cs5535_mfgpt_timer *wdt_timer; 52 static int safe_close; 53 54 static void geodewdt_ping(void) 55 { 56 /* Stop the counter */ 57 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 58 59 /* Reset the counter */ 60 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 61 62 /* Enable the counter */ 63 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); 64 } 65 66 static void geodewdt_disable(void) 67 { 68 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 69 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 70 } 71 72 static int geodewdt_set_heartbeat(int val) 73 { 74 if (val < 1 || val > GEODEWDT_MAX_SECONDS) 75 return -EINVAL; 76 77 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 78 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ); 79 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 80 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); 81 82 timeout = val; 83 return 0; 84 } 85 86 static int geodewdt_open(struct inode *inode, struct file *file) 87 { 88 if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags)) 89 return -EBUSY; 90 91 if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags)) 92 __module_get(THIS_MODULE); 93 94 geodewdt_ping(); 95 return nonseekable_open(inode, file); 96 } 97 98 static int geodewdt_release(struct inode *inode, struct file *file) 99 { 100 if (safe_close) { 101 geodewdt_disable(); 102 module_put(THIS_MODULE); 103 } else { 104 pr_crit("Unexpected close - watchdog is not stopping\n"); 105 geodewdt_ping(); 106 107 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags); 108 } 109 110 clear_bit(WDT_FLAGS_OPEN, &wdt_flags); 111 safe_close = 0; 112 return 0; 113 } 114 115 static ssize_t geodewdt_write(struct file *file, const char __user *data, 116 size_t len, loff_t *ppos) 117 { 118 if (len) { 119 if (!nowayout) { 120 size_t i; 121 safe_close = 0; 122 123 for (i = 0; i != len; i++) { 124 char c; 125 126 if (get_user(c, data + i)) 127 return -EFAULT; 128 129 if (c == 'V') 130 safe_close = 1; 131 } 132 } 133 134 geodewdt_ping(); 135 } 136 return len; 137 } 138 139 static long geodewdt_ioctl(struct file *file, unsigned int cmd, 140 unsigned long arg) 141 { 142 void __user *argp = (void __user *)arg; 143 int __user *p = argp; 144 int interval; 145 146 static const struct watchdog_info ident = { 147 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING 148 | WDIOF_MAGICCLOSE, 149 .firmware_version = 1, 150 .identity = WATCHDOG_NAME, 151 }; 152 153 switch (cmd) { 154 case WDIOC_GETSUPPORT: 155 return copy_to_user(argp, &ident, 156 sizeof(ident)) ? -EFAULT : 0; 157 break; 158 159 case WDIOC_GETSTATUS: 160 case WDIOC_GETBOOTSTATUS: 161 return put_user(0, p); 162 163 case WDIOC_SETOPTIONS: 164 { 165 int options, ret = -EINVAL; 166 167 if (get_user(options, p)) 168 return -EFAULT; 169 170 if (options & WDIOS_DISABLECARD) { 171 geodewdt_disable(); 172 ret = 0; 173 } 174 175 if (options & WDIOS_ENABLECARD) { 176 geodewdt_ping(); 177 ret = 0; 178 } 179 180 return ret; 181 } 182 case WDIOC_KEEPALIVE: 183 geodewdt_ping(); 184 return 0; 185 186 case WDIOC_SETTIMEOUT: 187 if (get_user(interval, p)) 188 return -EFAULT; 189 190 if (geodewdt_set_heartbeat(interval)) 191 return -EINVAL; 192 /* Fall through */ 193 case WDIOC_GETTIMEOUT: 194 return put_user(timeout, p); 195 196 default: 197 return -ENOTTY; 198 } 199 200 return 0; 201 } 202 203 static const struct file_operations geodewdt_fops = { 204 .owner = THIS_MODULE, 205 .llseek = no_llseek, 206 .write = geodewdt_write, 207 .unlocked_ioctl = geodewdt_ioctl, 208 .open = geodewdt_open, 209 .release = geodewdt_release, 210 }; 211 212 static struct miscdevice geodewdt_miscdev = { 213 .minor = WATCHDOG_MINOR, 214 .name = "watchdog", 215 .fops = &geodewdt_fops, 216 }; 217 218 static int geodewdt_probe(struct platform_device *dev) 219 { 220 int ret; 221 222 wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING); 223 if (!wdt_timer) { 224 pr_err("No timers were available\n"); 225 return -ENODEV; 226 } 227 228 /* Set up the timer */ 229 230 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 231 GEODEWDT_SCALE | (3 << 8)); 232 233 /* Set up comparator 2 to reset when the event fires */ 234 cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1); 235 236 /* Set up the initial timeout */ 237 238 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, 239 timeout * GEODEWDT_HZ); 240 241 ret = misc_register(&geodewdt_miscdev); 242 243 return ret; 244 } 245 246 static int geodewdt_remove(struct platform_device *dev) 247 { 248 misc_deregister(&geodewdt_miscdev); 249 return 0; 250 } 251 252 static void geodewdt_shutdown(struct platform_device *dev) 253 { 254 geodewdt_disable(); 255 } 256 257 static struct platform_driver geodewdt_driver = { 258 .probe = geodewdt_probe, 259 .remove = geodewdt_remove, 260 .shutdown = geodewdt_shutdown, 261 .driver = { 262 .owner = THIS_MODULE, 263 .name = DRV_NAME, 264 }, 265 }; 266 267 static int __init geodewdt_init(void) 268 { 269 int ret; 270 271 ret = platform_driver_register(&geodewdt_driver); 272 if (ret) 273 return ret; 274 275 geodewdt_platform_device = platform_device_register_simple(DRV_NAME, 276 -1, NULL, 0); 277 if (IS_ERR(geodewdt_platform_device)) { 278 ret = PTR_ERR(geodewdt_platform_device); 279 goto err; 280 } 281 282 return 0; 283 err: 284 platform_driver_unregister(&geodewdt_driver); 285 return ret; 286 } 287 288 static void __exit geodewdt_exit(void) 289 { 290 platform_device_unregister(geodewdt_platform_device); 291 platform_driver_unregister(&geodewdt_driver); 292 } 293 294 module_init(geodewdt_init); 295 module_exit(geodewdt_exit); 296 297 MODULE_AUTHOR("Advanced Micro Devices, Inc"); 298 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver"); 299 MODULE_LICENSE("GPL"); 300