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