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 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 fallthrough; 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 .compat_ioctl = compat_ptr_ioctl, 203 .open = geodewdt_open, 204 .release = geodewdt_release, 205 }; 206 207 static struct miscdevice geodewdt_miscdev = { 208 .minor = WATCHDOG_MINOR, 209 .name = "watchdog", 210 .fops = &geodewdt_fops, 211 }; 212 213 static int __init geodewdt_probe(struct platform_device *dev) 214 { 215 int ret; 216 217 wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING); 218 if (!wdt_timer) { 219 pr_err("No timers were available\n"); 220 return -ENODEV; 221 } 222 223 /* Set up the timer */ 224 225 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 226 GEODEWDT_SCALE | (3 << 8)); 227 228 /* Set up comparator 2 to reset when the event fires */ 229 cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1); 230 231 /* Set up the initial timeout */ 232 233 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, 234 timeout * GEODEWDT_HZ); 235 236 ret = misc_register(&geodewdt_miscdev); 237 238 return ret; 239 } 240 241 static void geodewdt_remove(struct platform_device *dev) 242 { 243 misc_deregister(&geodewdt_miscdev); 244 } 245 246 static void geodewdt_shutdown(struct platform_device *dev) 247 { 248 geodewdt_disable(); 249 } 250 251 static struct platform_driver geodewdt_driver = { 252 .remove_new = geodewdt_remove, 253 .shutdown = geodewdt_shutdown, 254 .driver = { 255 .name = DRV_NAME, 256 }, 257 }; 258 259 static int __init geodewdt_init(void) 260 { 261 int ret; 262 263 geodewdt_platform_device = platform_device_register_simple(DRV_NAME, 264 -1, NULL, 0); 265 if (IS_ERR(geodewdt_platform_device)) 266 return PTR_ERR(geodewdt_platform_device); 267 268 ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe); 269 if (ret) 270 goto err; 271 272 return 0; 273 err: 274 platform_device_unregister(geodewdt_platform_device); 275 return ret; 276 } 277 278 static void __exit geodewdt_exit(void) 279 { 280 platform_device_unregister(geodewdt_platform_device); 281 platform_driver_unregister(&geodewdt_driver); 282 } 283 284 module_init(geodewdt_init); 285 module_exit(geodewdt_exit); 286 287 MODULE_AUTHOR("Advanced Micro Devices, Inc"); 288 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver"); 289 MODULE_LICENSE("GPL"); 290