drivers/watchdog/wm8350_wdt.c

   1 /*
   2  * Watchdog driver for the wm8350
   3  *
   4  * Copyright (C) 2007, 2008 Wolfson Microelectronics <linux@wolfsonmicro.com>
   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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/fs.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/watchdog.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/mfd/wm8350/core.h>
  23
  24 static int nowayout = WATCHDOG_NOWAYOUT;
  25 module_param(nowayout, int, 0);
  26 MODULE_PARM_DESC(nowayout,
  27                  "Watchdog cannot be stopped once started (default="
  28                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  29
  30 static unsigned long wm8350_wdt_users;
  31 static struct miscdevice wm8350_wdt_miscdev;
  32 static int wm8350_wdt_expect_close;
  33 static DEFINE_MUTEX(wdt_mutex);
  34
  35 static struct {
  36         int time;  /* Seconds */
  37         u16 val;   /* To be set in WM8350_SYSTEM_CONTROL_2 */
  38 } wm8350_wdt_cfgs[] = {
  39         { 1, 0x02 },
  40         { 2, 0x04 },
  41         { 4, 0x05 },
  42 };
  43
  44 static struct wm8350 *get_wm8350(void)
  45 {
  46         return dev_get_drvdata(wm8350_wdt_miscdev.parent);
  47 }
  48
  49 static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
  50 {
  51         int ret;
  52         u16 reg;
  53
  54         mutex_lock(&wdt_mutex);
  55         wm8350_reg_unlock(wm8350);
  56
  57         reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
  58         reg &= ~WM8350_WDOG_TO_MASK;
  59         reg |= value;
  60         ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
  61
  62         wm8350_reg_lock(wm8350);
  63         mutex_unlock(&wdt_mutex);
  64
  65         return ret;
  66 }
  67
  68 static int wm8350_wdt_start(struct wm8350 *wm8350)
  69 {
  70         int ret;
  71         u16 reg;
  72
  73         mutex_lock(&wdt_mutex);
  74         wm8350_reg_unlock(wm8350);
  75
  76         reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
  77         reg &= ~WM8350_WDOG_MODE_MASK;
  78         reg |= 0x20;
  79         ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
  80
  81         wm8350_reg_lock(wm8350);
  82         mutex_unlock(&wdt_mutex);
  83
  84         return ret;
  85 }
  86
  87 static int wm8350_wdt_stop(struct wm8350 *wm8350)
  88 {
  89         int ret;
  90         u16 reg;
  91
  92         mutex_lock(&wdt_mutex);
  93         wm8350_reg_unlock(wm8350);
  94
  95         reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
  96         reg &= ~WM8350_WDOG_MODE_MASK;
  97         ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
  98
  99         wm8350_reg_lock(wm8350);
 100         mutex_unlock(&wdt_mutex);
 101
 102         return ret;
 103 }
 104
 105 static int wm8350_wdt_kick(struct wm8350 *wm8350)
 106 {
 107         int ret;
 108         u16 reg;
 109
 110         mutex_lock(&wdt_mutex);
 111
 112         reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
 113         ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);
 114
 115         mutex_unlock(&wdt_mutex);
 116
 117         return ret;
 118 }
 119
 120 static int wm8350_wdt_open(struct inode *inode, struct file *file)
 121 {
 122         struct wm8350 *wm8350 = get_wm8350();
 123         int ret;
 124
 125         if (!wm8350)
 126                 return -ENODEV;
 127
 128         if (test_and_set_bit(0, &wm8350_wdt_users))
 129                 return -EBUSY;
 130
 131         ret = wm8350_wdt_start(wm8350);
 132         if (ret != 0)
 133                 return ret;
 134
 135         return nonseekable_open(inode, file);
 136 }
 137
 138 static int wm8350_wdt_release(struct inode *inode, struct file *file)
 139 {
 140         struct wm8350 *wm8350 = get_wm8350();
 141
 142         if (wm8350_wdt_expect_close)
 143                 wm8350_wdt_stop(wm8350);
 144         else {
 145                 dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");
 146                 wm8350_wdt_kick(wm8350);
 147         }
 148
 149         clear_bit(0, &wm8350_wdt_users);
 150
 151         return 0;
 152 }
 153
 154 static ssize_t wm8350_wdt_write(struct file *file,
 155                                 const char __user *data, size_t count,
 156                                 loff_t *ppos)
 157 {
 158         struct wm8350 *wm8350 = get_wm8350();
 159         size_t i;
 160
 161         if (count) {
 162                 wm8350_wdt_kick(wm8350);
 163
 164                 if (!nowayout) {
 165                         /* In case it was set long ago */
 166                         wm8350_wdt_expect_close = 0;
 167
 168                         /* scan to see whether or not we got the magic
 169                            character */
 170                         for (i = 0; i != count; i++) {
 171                                 char c;
 172                                 if (get_user(c, data + i))
 173                                         return -EFAULT;
 174                                 if (c == 'V')
 175                                         wm8350_wdt_expect_close = 42;
 176                         }
 177                 }
 178         }
 179         return count;
 180 }
 181
 182 static const struct watchdog_info ident = {
 183         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 184         .identity = "WM8350 Watchdog",
 185 };
 186
 187 static long wm8350_wdt_ioctl(struct file *file, unsigned int cmd,
 188                              unsigned long arg)
 189 {
 190         struct wm8350 *wm8350 = get_wm8350();
 191         int ret = -ENOTTY, time, i;
 192         void __user *argp = (void __user *)arg;
 193         int __user *p = argp;
 194         u16 reg;
 195
 196         switch (cmd) {
 197         case WDIOC_GETSUPPORT:
 198                 ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 199                 break;
 200
 201         case WDIOC_GETSTATUS:
 202         case WDIOC_GETBOOTSTATUS:
 203                 ret = put_user(0, p);
 204                 break;
 205
 206         case WDIOC_SETOPTIONS:
 207         {
 208                 int options;
 209
 210                 if (get_user(options, p))
 211                         return -EFAULT;
 212
 213                 ret = -EINVAL;
 214
 215                 /* Setting both simultaneously means at least one must fail */
 216                 if (options == WDIOS_DISABLECARD)
 217                         ret = wm8350_wdt_stop(wm8350);
 218
 219                 if (options == WDIOS_ENABLECARD)
 220                         ret = wm8350_wdt_start(wm8350);
 221                 break;
 222         }
 223
 224         case WDIOC_KEEPALIVE:
 225                 ret = wm8350_wdt_kick(wm8350);
 226                 break;
 227
 228         case WDIOC_SETTIMEOUT:
 229                 ret = get_user(time, p);
 230                 if (ret)
 231                         break;
 232
 233                 if (time == 0) {
 234                         if (nowayout)
 235                                 ret = -EINVAL;
 236                         else
 237                                 wm8350_wdt_stop(wm8350);
 238                         break;
 239                 }
 240
 241                 for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
 242                         if (wm8350_wdt_cfgs[i].time == time)
 243                                 break;
 244                 if (i == ARRAY_SIZE(wm8350_wdt_cfgs))
 245                         ret = -EINVAL;
 246                 else
 247                         ret = wm8350_wdt_set_timeout(wm8350,
 248                                                      wm8350_wdt_cfgs[i].val);
 249                 break;
 250
 251         case WDIOC_GETTIMEOUT:
 252                 reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
 253                 reg &= WM8350_WDOG_TO_MASK;
 254                 for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
 255                         if (wm8350_wdt_cfgs[i].val == reg)
 256                                 break;
 257                 if (i == ARRAY_SIZE(wm8350_wdt_cfgs)) {
 258                         dev_warn(wm8350->dev,
 259                                  "Unknown watchdog configuration: %x\n", reg);
 260                         ret = -EINVAL;
 261                 } else
 262                         ret = put_user(wm8350_wdt_cfgs[i].time, p);
 263
 264         }
 265
 266         return ret;
 267 }
 268
 269 static const struct file_operations wm8350_wdt_fops = {
 270         .owner = THIS_MODULE,
 271         .llseek = no_llseek,
 272         .write = wm8350_wdt_write,
 273         .unlocked_ioctl = wm8350_wdt_ioctl,
 274         .open = wm8350_wdt_open,
 275         .release = wm8350_wdt_release,
 276 };
 277
 278 static struct miscdevice wm8350_wdt_miscdev = {
 279         .minor = WATCHDOG_MINOR,
 280         .name = "watchdog",
 281         .fops = &wm8350_wdt_fops,
 282 };
 283
 284 static int __devinit wm8350_wdt_probe(struct platform_device *pdev)
 285 {
 286         struct wm8350 *wm8350 = platform_get_drvdata(pdev);
 287
 288         if (!wm8350) {
 289                 pr_err("No driver data supplied\n");
 290                 return -ENODEV;
 291         }
 292
 293         /* Default to 4s timeout */
 294         wm8350_wdt_set_timeout(wm8350, 0x05);
 295
 296         wm8350_wdt_miscdev.parent = &pdev->dev;
 297
 298         return misc_register(&wm8350_wdt_miscdev);
 299 }
 300
 301 static int __devexit wm8350_wdt_remove(struct platform_device *pdev)
 302 {
 303         misc_deregister(&wm8350_wdt_miscdev);
 304
 305         return 0;
 306 }
 307
 308 static struct platform_driver wm8350_wdt_driver = {
 309         .probe = wm8350_wdt_probe,
 310         .remove = __devexit_p(wm8350_wdt_remove),
 311         .driver = {
 312                 .name = "wm8350-wdt",
 313         },
 314 };
 315
 316 module_platform_driver(wm8350_wdt_driver);
 317
 318 MODULE_AUTHOR("Mark Brown");
 319 MODULE_DESCRIPTION("WM8350 Watchdog");
 320 MODULE_LICENSE("GPL");
 321 MODULE_ALIAS("platform:wm8350-wdt");