1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Watchdog timer for machines with the CS5535/CS5536 companion chip 3 * 4 * Copyright (C) 2006-2007, Advanced Micro Devices, Inc. 5 * Copyright (C) 2009 Andres Salomon <dilinger@collabora.co.uk> 6 */ 7 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <linux/module.h> 11 #include <linux/moduleparam.h> 12 #include <linux/types.h> 13 #include <linux/miscdevice.h> 14 #include <linux/watchdog.h> 15 #include <linux/fs.h> 16 #include <linux/platform_device.h> 17 #include <linux/reboot.h> 18 #include <linux/uaccess.h> 19 20 #include <linux/cs5535.h> 21 22 #define GEODEWDT_HZ 500 23 #define GEODEWDT_SCALE 6 24 #define GEODEWDT_MAX_SECONDS 131 25 26 #define WDT_FLAGS_OPEN 1 27 #define WDT_FLAGS_ORPHAN 2 28 29 #define DRV_NAME "geodewdt" 30 #define WATCHDOG_NAME "Geode GX/LX WDT" 31 #define WATCHDOG_TIMEOUT 60 32 33 static int timeout = WATCHDOG_TIMEOUT; 34 module_param(timeout, int, 0); 35 MODULE_PARM_DESC(timeout, 36 "Watchdog timeout in seconds. 1<= timeout <=131, default=" 37 __MODULE_STRING(WATCHDOG_TIMEOUT) "."); 38 39 static bool nowayout = WATCHDOG_NOWAYOUT; 40 module_param(nowayout, bool, 0); 41 MODULE_PARM_DESC(nowayout, 42 "Watchdog cannot be stopped once started (default=" 43 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 44 45 static struct platform_device *geodewdt_platform_device; 46 static unsigned long wdt_flags; 47 static struct cs5535_mfgpt_timer *wdt_timer; 48 static int safe_close; 49 50 static void geodewdt_ping(void) 51 { 52 /* Stop the counter */ 53 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 54 55 /* Reset the counter */ 56 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 57 58 /* Enable the counter */ 59 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); 60 } 61 62 static void geodewdt_disable(void) 63 { 64 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 65 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 66 } 67 68 static int geodewdt_set_heartbeat(int val) 69 { 70 if (val < 1 || val > GEODEWDT_MAX_SECONDS) 71 return -EINVAL; 72 73 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0); 74 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ); 75 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0); 76 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); 77 78 timeout = val; 79 return 0; 80 } 81 82 static int geodewdt_open(struct inode *inode, struct file *file) 83 { 84 if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags)) 85 return -EBUSY; 86 87 if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags)) 88 __module_get(THIS_MODULE); 89 90 geodewdt_ping(); 91 return stream_open(inode, file); 92 } 93 94 static int geodewdt_release(struct inode *inode, struct file *file) 95 { 96 if (safe_close) { 97 geodewdt_disable(); 98 module_put(THIS_MODULE); 99 } else { 100 pr_crit("Unexpected close - watchdog is not stopping\n"); 101 geodewdt_ping(); 102 103 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags); 104 } 105 106 clear_bit(WDT_FLAGS_OPEN, &wdt_flags); 107 safe_close = 0; 108 return 0; 109 } 110 111 static ssize_t geodewdt_write(struct file *file, const char __user *data, 112 size_t len, loff_t *ppos) 113 { 114 if (len) { 115 if (!nowayout) { 116 size_t i; 117 safe_close = 0; 118 119 for (i = 0; i != len; i++) { 120 char c; 121 122 if (get_user(c, data + i)) 123 return -EFAULT; 124 125 if (c == 'V') 126 safe_close = 1; 127 } 128 } 129 130 geodewdt_ping(); 131 } 132 return len; 133 } 134 135 static long geodewdt_ioctl(struct file *file, unsigned int cmd, 136 unsigned long arg) 137 { 138 void __user *argp = (void __user *)arg; 139 int __user *p = argp; 140 int interval; 141 142 static const struct watchdog_info ident = { 143 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING 144 | WDIOF_MAGICCLOSE, 145 .firmware_version = 1, 146 .identity = WATCHDOG_NAME, 147 }; 148 149 switch (cmd) { 150 case WDIOC_GETSUPPORT: 151 return copy_to_user(argp, &ident, 152 sizeof(ident)) ? -EFAULT : 0; 153 break; 154 155 case WDIOC_GETSTATUS: 156 case WDIOC_GETBOOTSTATUS: 157 return put_user(0, p); 158 159 case WDIOC_SETOPTIONS: 160 { 161 int options, ret = -EINVAL; 162 163 if (get_user(options, p)) 164 return -EFAULT; 165 166 if (options & WDIOS_DISABLECARD) { 167 geodewdt_disable(); 168 ret = 0; 169 } 170 171 if (options & WDIOS_ENABLECARD) { 172 geodewdt_ping(); 173 ret = 0; 174 } 175 176 return ret; 177 } 178 case WDIOC_KEEPALIVE: 179 geodewdt_ping(); 180 return 0; 181 182 case WDIOC_SETTIMEOUT: 183 if (get_user(interval, p)) 184 return -EFAULT; 185 186 if (geodewdt_set_heartbeat(interval)) 187 return -EINVAL; 188 /* Fall through */ 189 case WDIOC_GETTIMEOUT: 190 return put_user(timeout, p); 191 192 default: 193 return -ENOTTY; 194 } 195 196 return 0; 197 } 198 199 static const struct file_operations geodewdt_fops = { 200 .owner = THIS_MODULE, 201 .llseek = no_llseek, 202 .write = geodewdt_write, 203 .unlocked_ioctl = geodewdt_ioctl, 204 .compat_ioctl = compat_ptr_ioctl, 205 .open = geodewdt_open, 206 .release = geodewdt_release, 207 }; 208 209 static struct miscdevice geodewdt_miscdev = { 210 .minor = WATCHDOG_MINOR, 211 .name = "watchdog", 212 .fops = &geodewdt_fops, 213 }; 214 215 static int __init geodewdt_probe(struct platform_device *dev) 216 { 217 int ret; 218 219 wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING); 220 if (!wdt_timer) { 221 pr_err("No timers were available\n"); 222 return -ENODEV; 223 } 224 225 /* Set up the timer */ 226 227 cs5535_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 cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1); 232 233 /* Set up the initial timeout */ 234 235 cs5535_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 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 .remove = geodewdt_remove, 256 .shutdown = geodewdt_shutdown, 257 .driver = { 258 .name = DRV_NAME, 259 }, 260 }; 261 262 static int __init geodewdt_init(void) 263 { 264 int ret; 265 266 geodewdt_platform_device = platform_device_register_simple(DRV_NAME, 267 -1, NULL, 0); 268 if (IS_ERR(geodewdt_platform_device)) 269 return PTR_ERR(geodewdt_platform_device); 270 271 ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe); 272 if (ret) 273 goto err; 274 275 return 0; 276 err: 277 platform_device_unregister(geodewdt_platform_device); 278 return ret; 279 } 280 281 static void __exit geodewdt_exit(void) 282 { 283 platform_device_unregister(geodewdt_platform_device); 284 platform_driver_unregister(&geodewdt_driver); 285 } 286 287 module_init(geodewdt_init); 288 module_exit(geodewdt_exit); 289 290 MODULE_AUTHOR("Advanced Micro Devices, Inc"); 291 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver"); 292 MODULE_LICENSE("GPL"); 293