1/* 2 * Watchdog driver for the wm831x PMICs 3 * 4 * Copyright (C) 2009 Wolfson Microelectronics 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 9 */ 10 11#include <linux/module.h> 12#include <linux/moduleparam.h> 13#include <linux/types.h> 14#include <linux/kernel.h> 15#include <linux/fs.h> 16#include <linux/miscdevice.h> 17#include <linux/platform_device.h> 18#include <linux/watchdog.h> 19#include <linux/uaccess.h> 20#include <linux/gpio.h> 21 22#include <linux/mfd/wm831x/core.h> 23#include <linux/mfd/wm831x/pdata.h> 24#include <linux/mfd/wm831x/watchdog.h> 25 26static int nowayout = WATCHDOG_NOWAYOUT; 27module_param(nowayout, int, 0); 28MODULE_PARM_DESC(nowayout, 29 "Watchdog cannot be stopped once started (default=" 30 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 31 32static unsigned long wm831x_wdt_users; 33static struct miscdevice wm831x_wdt_miscdev; 34static int wm831x_wdt_expect_close; 35static DEFINE_MUTEX(wdt_mutex); 36static struct wm831x *wm831x; 37static unsigned int update_gpio; 38static unsigned int update_state; 39 40/* We can't use the sub-second values here but they're included 41 * for completeness. */ 42static struct { 43 int time; /* Seconds */ 44 u16 val; /* WDOG_TO value */ 45} wm831x_wdt_cfgs[] = { 46 { 1, 2 }, 47 { 2, 3 }, 48 { 4, 4 }, 49 { 8, 5 }, 50 { 16, 6 }, 51 { 32, 7 }, 52 { 33, 7 }, /* Actually 32.768s so include both, others round down */ 53}; 54 55static int wm831x_wdt_set_timeout(struct wm831x *wm831x, u16 value) 56{ 57 int ret; 58 59 mutex_lock(&wdt_mutex); 60 61 ret = wm831x_reg_unlock(wm831x); 62 if (ret == 0) { 63 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG, 64 WM831X_WDOG_TO_MASK, value); 65 wm831x_reg_lock(wm831x); 66 } else { 67 dev_err(wm831x->dev, "Failed to unlock security key: %d\n", 68 ret); 69 } 70 71 mutex_unlock(&wdt_mutex); 72 73 return ret; 74} 75 76static int wm831x_wdt_start(struct wm831x *wm831x) 77{ 78 int ret; 79 80 mutex_lock(&wdt_mutex); 81 82 ret = wm831x_reg_unlock(wm831x); 83 if (ret == 0) { 84 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG, 85 WM831X_WDOG_ENA, WM831X_WDOG_ENA); 86 wm831x_reg_lock(wm831x); 87 } else { 88 dev_err(wm831x->dev, "Failed to unlock security key: %d\n", 89 ret); 90 } 91 92 mutex_unlock(&wdt_mutex); 93 94 return ret; 95} 96 97static int wm831x_wdt_stop(struct wm831x *wm831x) 98{ 99 int ret; 100 101 mutex_lock(&wdt_mutex); 102 103 ret = wm831x_reg_unlock(wm831x); 104 if (ret == 0) { 105 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG, 106 WM831X_WDOG_ENA, 0); 107 wm831x_reg_lock(wm831x); 108 } else { 109 dev_err(wm831x->dev, "Failed to unlock security key: %d\n", 110 ret); 111 } 112 113 mutex_unlock(&wdt_mutex); 114 115 return ret; 116} 117 118static int wm831x_wdt_kick(struct wm831x *wm831x) 119{ 120 int ret; 121 u16 reg; 122 123 mutex_lock(&wdt_mutex); 124 125 if (update_gpio) { 126 gpio_set_value_cansleep(update_gpio, update_state); 127 update_state = !update_state; 128 ret = 0; 129 goto out; 130 } 131 132 133 reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG); 134 135 if (!(reg & WM831X_WDOG_RST_SRC)) { 136 dev_err(wm831x->dev, "Hardware watchdog update unsupported\n"); 137 ret = -EINVAL; 138 goto out; 139 } 140 141 reg |= WM831X_WDOG_RESET; 142 143 ret = wm831x_reg_unlock(wm831x); 144 if (ret == 0) { 145 ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg); 146 wm831x_reg_lock(wm831x); 147 } else { 148 dev_err(wm831x->dev, "Failed to unlock security key: %d\n", 149 ret); 150 } 151 152out: 153 mutex_unlock(&wdt_mutex); 154 155 return ret; 156} 157 158static int wm831x_wdt_open(struct inode *inode, struct file *file) 159{ 160 int ret; 161 162 if (!wm831x) 163 return -ENODEV; 164 165 if (test_and_set_bit(0, &wm831x_wdt_users)) 166 return -EBUSY; 167 168 ret = wm831x_wdt_start(wm831x); 169 if (ret != 0) 170 return ret; 171 172 return nonseekable_open(inode, file); 173} 174 175static int wm831x_wdt_release(struct inode *inode, struct file *file) 176{ 177 if (wm831x_wdt_expect_close) 178 wm831x_wdt_stop(wm831x); 179 else { 180 dev_warn(wm831x->dev, "Watchdog device closed uncleanly\n"); 181 wm831x_wdt_kick(wm831x); 182 } 183 184 clear_bit(0, &wm831x_wdt_users); 185 186 return 0; 187} 188 189static ssize_t wm831x_wdt_write(struct file *file, 190 const char __user *data, size_t count, 191 loff_t *ppos) 192{ 193 size_t i; 194 195 if (count) { 196 wm831x_wdt_kick(wm831x); 197 198 if (!nowayout) { 199 /* In case it was set long ago */ 200 wm831x_wdt_expect_close = 0; 201 202 /* scan to see whether or not we got the magic 203 character */ 204 for (i = 0; i != count; i++) { 205 char c; 206 if (get_user(c, data + i)) 207 return -EFAULT; 208 if (c == 'V') 209 wm831x_wdt_expect_close = 42; 210 } 211 } 212 } 213 return count; 214} 215 216static const struct watchdog_info ident = { 217 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 218 .identity = "WM831x Watchdog", 219}; 220 221static long wm831x_wdt_ioctl(struct file *file, unsigned int cmd, 222 unsigned long arg) 223{ 224 int ret = -ENOTTY, time, i; 225 void __user *argp = (void __user *)arg; 226 int __user *p = argp; 227 u16 reg; 228 229 switch (cmd) { 230 case WDIOC_GETSUPPORT: 231 ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 232 break; 233 234 case WDIOC_GETSTATUS: 235 case WDIOC_GETBOOTSTATUS: 236 ret = put_user(0, p); 237 break; 238 239 case WDIOC_SETOPTIONS: 240 { 241 int options; 242 243 if (get_user(options, p)) 244 return -EFAULT; 245 246 ret = -EINVAL; 247 248 /* Setting both simultaneously means at least one must fail */ 249 if (options == WDIOS_DISABLECARD) 250 ret = wm831x_wdt_start(wm831x); 251 252 if (options == WDIOS_ENABLECARD) 253 ret = wm831x_wdt_stop(wm831x); 254 break; 255 } 256 257 case WDIOC_KEEPALIVE: 258 ret = wm831x_wdt_kick(wm831x); 259 break; 260 261 case WDIOC_SETTIMEOUT: 262 ret = get_user(time, p); 263 if (ret) 264 break; 265 266 if (time == 0) { 267 if (nowayout) 268 ret = -EINVAL; 269 else 270 wm831x_wdt_stop(wm831x); 271 break; 272 } 273 274 for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++) 275 if (wm831x_wdt_cfgs[i].time == time) 276 break; 277 if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) 278 ret = -EINVAL; 279 else 280 ret = wm831x_wdt_set_timeout(wm831x, 281 wm831x_wdt_cfgs[i].val); 282 break; 283 284 case WDIOC_GETTIMEOUT: 285 reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG); 286 reg &= WM831X_WDOG_TO_MASK; 287 for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++) 288 if (wm831x_wdt_cfgs[i].val == reg) 289 break; 290 if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) { 291 dev_warn(wm831x->dev, 292 "Unknown watchdog configuration: %x\n", reg); 293 ret = -EINVAL; 294 } else 295 ret = put_user(wm831x_wdt_cfgs[i].time, p); 296 297 } 298 299 return ret; 300} 301 302static const struct file_operations wm831x_wdt_fops = { 303 .owner = THIS_MODULE, 304 .llseek = no_llseek, 305 .write = wm831x_wdt_write, 306 .unlocked_ioctl = wm831x_wdt_ioctl, 307 .open = wm831x_wdt_open, 308 .release = wm831x_wdt_release, 309}; 310 311static struct miscdevice wm831x_wdt_miscdev = { 312 .minor = WATCHDOG_MINOR, 313 .name = "watchdog", 314 .fops = &wm831x_wdt_fops, 315}; 316 317static int __devinit wm831x_wdt_probe(struct platform_device *pdev) 318{ 319 struct wm831x_pdata *chip_pdata; 320 struct wm831x_watchdog_pdata *pdata; 321 int reg, ret; 322 323 wm831x = dev_get_drvdata(pdev->dev.parent); 324 325 ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG); 326 if (ret < 0) { 327 dev_err(wm831x->dev, "Failed to read watchdog status: %d\n", 328 ret); 329 goto err; 330 } 331 reg = ret; 332 333 if (reg & WM831X_WDOG_DEBUG) 334 dev_warn(wm831x->dev, "Watchdog is paused\n"); 335 336 /* Apply any configuration */ 337 if (pdev->dev.parent->platform_data) { 338 chip_pdata = pdev->dev.parent->platform_data; 339 pdata = chip_pdata->watchdog; 340 } else { 341 pdata = NULL; 342 } 343 344 if (pdata) { 345 reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK | 346 WM831X_WDOG_RST_SRC); 347 348 reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT; 349 reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT; 350 reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT; 351 352 if (pdata->update_gpio) { 353 ret = gpio_request(pdata->update_gpio, 354 "Watchdog update"); 355 if (ret < 0) { 356 dev_err(wm831x->dev, 357 "Failed to request update GPIO: %d\n", 358 ret); 359 goto err; 360 } 361 362 ret = gpio_direction_output(pdata->update_gpio, 0); 363 if (ret != 0) { 364 dev_err(wm831x->dev, 365 "gpio_direction_output returned: %d\n", 366 ret); 367 goto err_gpio; 368 } 369 370 update_gpio = pdata->update_gpio; 371 372 /* Make sure the watchdog takes hardware updates */ 373 reg |= WM831X_WDOG_RST_SRC; 374 } 375 376 ret = wm831x_reg_unlock(wm831x); 377 if (ret == 0) { 378 ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg); 379 wm831x_reg_lock(wm831x); 380 } else { 381 dev_err(wm831x->dev, 382 "Failed to unlock security key: %d\n", ret); 383 goto err_gpio; 384 } 385 } 386 387 wm831x_wdt_miscdev.parent = &pdev->dev; 388 389 ret = misc_register(&wm831x_wdt_miscdev); 390 if (ret != 0) { 391 dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret); 392 goto err_gpio; 393 } 394 395 return 0; 396 397err_gpio: 398 if (update_gpio) { 399 gpio_free(update_gpio); 400 update_gpio = 0; 401 } 402err: 403 return ret; 404} 405 406static int __devexit wm831x_wdt_remove(struct platform_device *pdev) 407{ 408 if (update_gpio) { 409 gpio_free(update_gpio); 410 update_gpio = 0; 411 } 412 413 misc_deregister(&wm831x_wdt_miscdev); 414 415 return 0; 416} 417 418static struct platform_driver wm831x_wdt_driver = { 419 .probe = wm831x_wdt_probe, 420 .remove = __devexit_p(wm831x_wdt_remove), 421 .driver = { 422 .name = "wm831x-watchdog", 423 }, 424}; 425 426static int __init wm831x_wdt_init(void) 427{ 428 return platform_driver_register(&wm831x_wdt_driver); 429} 430module_init(wm831x_wdt_init); 431 432static void __exit wm831x_wdt_exit(void) 433{ 434 platform_driver_unregister(&wm831x_wdt_driver); 435} 436module_exit(wm831x_wdt_exit); 437 438MODULE_AUTHOR("Mark Brown"); 439MODULE_DESCRIPTION("WM831x Watchdog"); 440MODULE_LICENSE("GPL"); 441MODULE_ALIAS("platform:wm831x-watchdog"); 442