drivers/watchdog/twl4030_wdt.c

   1 /*
   2  * Copyright (C) Nokia Corporation
   3  *
   4  * Written by Timo Kokkonen <timo.t.kokkonen at nokia.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/types.h>
  23 #include <linux/slab.h>
  24 #include <linux/kernel.h>
  25 #include <linux/fs.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/i2c/twl.h>
  31
  32 #define TWL4030_WATCHDOG_CFG_REG_OFFS   0x3
  33
  34 #define TWL4030_WDT_STATE_OPEN          0x1
  35 #define TWL4030_WDT_STATE_ACTIVE        0x8
  36
  37 static struct platform_device *twl4030_wdt_dev;
  38
  39 struct twl4030_wdt {
  40         struct miscdevice       miscdev;
  41         int                     timer_margin;
  42         unsigned long           state;
  43 };
  44
  45 static bool nowayout = WATCHDOG_NOWAYOUT;
  46 module_param(nowayout, bool, 0);
  47 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  48         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  49
  50 static int twl4030_wdt_write(unsigned char val)
  51 {
  52         return twl_i2c_write_u8(TWL4030_MODULE_PM_RECEIVER, val,
  53                                         TWL4030_WATCHDOG_CFG_REG_OFFS);
  54 }
  55
  56 static int twl4030_wdt_enable(struct twl4030_wdt *wdt)
  57 {
  58         return twl4030_wdt_write(wdt->timer_margin + 1);
  59 }
  60
  61 static int twl4030_wdt_disable(struct twl4030_wdt *wdt)
  62 {
  63         return twl4030_wdt_write(0);
  64 }
  65
  66 static int twl4030_wdt_set_timeout(struct twl4030_wdt *wdt, int timeout)
  67 {
  68         if (timeout < 0 || timeout > 30) {
  69                 dev_warn(wdt->miscdev.parent,
  70                         "Timeout can only be in the range [0-30] seconds");
  71                 return -EINVAL;
  72         }
  73         wdt->timer_margin = timeout;
  74         return twl4030_wdt_enable(wdt);
  75 }
  76
  77 static ssize_t twl4030_wdt_write_fop(struct file *file,
  78                 const char __user *data, size_t len, loff_t *ppos)
  79 {
  80         struct twl4030_wdt *wdt = file->private_data;
  81
  82         if (len)
  83                 twl4030_wdt_enable(wdt);
  84
  85         return len;
  86 }
  87
  88 static long twl4030_wdt_ioctl(struct file *file,
  89                 unsigned int cmd, unsigned long arg)
  90 {
  91         void __user *argp = (void __user *)arg;
  92         int __user *p = argp;
  93         int new_margin;
  94         struct twl4030_wdt *wdt = file->private_data;
  95
  96         static const struct watchdog_info twl4030_wd_ident = {
  97                 .identity = "TWL4030 Watchdog",
  98                 .options = WDIOF_SETTIMEOUT,
  99                 .firmware_version = 0,
 100         };
 101
 102         switch (cmd) {
 103         case WDIOC_GETSUPPORT:
 104                 return copy_to_user(argp, &twl4030_wd_ident,
 105                                 sizeof(twl4030_wd_ident)) ? -EFAULT : 0;
 106
 107         case WDIOC_GETSTATUS:
 108         case WDIOC_GETBOOTSTATUS:
 109                 return put_user(0, p);
 110
 111         case WDIOC_KEEPALIVE:
 112                 twl4030_wdt_enable(wdt);
 113                 break;
 114
 115         case WDIOC_SETTIMEOUT:
 116                 if (get_user(new_margin, p))
 117                         return -EFAULT;
 118                 if (twl4030_wdt_set_timeout(wdt, new_margin))
 119                         return -EINVAL;
 120                 return put_user(wdt->timer_margin, p);
 121
 122         case WDIOC_GETTIMEOUT:
 123                 return put_user(wdt->timer_margin, p);
 124
 125         default:
 126                 return -ENOTTY;
 127         }
 128
 129         return 0;
 130 }
 131
 132 static int twl4030_wdt_open(struct inode *inode, struct file *file)
 133 {
 134         struct twl4030_wdt *wdt = platform_get_drvdata(twl4030_wdt_dev);
 135
 136         /* /dev/watchdog can only be opened once */
 137         if (test_and_set_bit(0, &wdt->state))
 138                 return -EBUSY;
 139
 140         wdt->state |= TWL4030_WDT_STATE_ACTIVE;
 141         file->private_data = (void *) wdt;
 142
 143         twl4030_wdt_enable(wdt);
 144         return nonseekable_open(inode, file);
 145 }
 146
 147 static int twl4030_wdt_release(struct inode *inode, struct file *file)
 148 {
 149         struct twl4030_wdt *wdt = file->private_data;
 150         if (nowayout) {
 151                 dev_alert(wdt->miscdev.parent,
 152                        "Unexpected close, watchdog still running!\n");
 153                 twl4030_wdt_enable(wdt);
 154         } else {
 155                 if (twl4030_wdt_disable(wdt))
 156                         return -EFAULT;
 157                 wdt->state &= ~TWL4030_WDT_STATE_ACTIVE;
 158         }
 159
 160         clear_bit(0, &wdt->state);
 161         return 0;
 162 }
 163
 164 static const struct file_operations twl4030_wdt_fops = {
 165         .owner          = THIS_MODULE,
 166         .llseek         = no_llseek,
 167         .open           = twl4030_wdt_open,
 168         .release        = twl4030_wdt_release,
 169         .unlocked_ioctl = twl4030_wdt_ioctl,
 170         .write          = twl4030_wdt_write_fop,
 171 };
 172
 173 static int twl4030_wdt_probe(struct platform_device *pdev)
 174 {
 175         int ret = 0;
 176         struct twl4030_wdt *wdt;
 177
 178         wdt = kzalloc(sizeof(struct twl4030_wdt), GFP_KERNEL);
 179         if (!wdt)
 180                 return -ENOMEM;
 181
 182         wdt->state              = 0;
 183         wdt->timer_margin       = 30;
 184         wdt->miscdev.parent     = &pdev->dev;
 185         wdt->miscdev.fops       = &twl4030_wdt_fops;
 186         wdt->miscdev.minor      = WATCHDOG_MINOR;
 187         wdt->miscdev.name       = "watchdog";
 188
 189         platform_set_drvdata(pdev, wdt);
 190
 191         twl4030_wdt_dev = pdev;
 192
 193         twl4030_wdt_disable(wdt);
 194
 195         ret = misc_register(&wdt->miscdev);
 196         if (ret) {
 197                 dev_err(wdt->miscdev.parent,
 198                         "Failed to register misc device\n");
 199                 platform_set_drvdata(pdev, NULL);
 200                 kfree(wdt);
 201                 twl4030_wdt_dev = NULL;
 202                 return ret;
 203         }
 204         return 0;
 205 }
 206
 207 static int twl4030_wdt_remove(struct platform_device *pdev)
 208 {
 209         struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
 210
 211         if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
 212                 if (twl4030_wdt_disable(wdt))
 213                         return -EFAULT;
 214
 215         wdt->state &= ~TWL4030_WDT_STATE_ACTIVE;
 216         misc_deregister(&wdt->miscdev);
 217
 218         platform_set_drvdata(pdev, NULL);
 219         kfree(wdt);
 220         twl4030_wdt_dev = NULL;
 221
 222         return 0;
 223 }
 224
 225 #ifdef CONFIG_PM
 226 static int twl4030_wdt_suspend(struct platform_device *pdev, pm_message_t state)
 227 {
 228         struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
 229         if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
 230                 return twl4030_wdt_disable(wdt);
 231
 232         return 0;
 233 }
 234
 235 static int twl4030_wdt_resume(struct platform_device *pdev)
 236 {
 237         struct twl4030_wdt *wdt = platform_get_drvdata(pdev);
 238         if (wdt->state & TWL4030_WDT_STATE_ACTIVE)
 239                 return twl4030_wdt_enable(wdt);
 240
 241         return 0;
 242 }
 243 #else
 244 #define twl4030_wdt_suspend        NULL
 245 #define twl4030_wdt_resume         NULL
 246 #endif
 247
 248 static struct platform_driver twl4030_wdt_driver = {
 249         .probe          = twl4030_wdt_probe,
 250         .remove         = twl4030_wdt_remove,
 251         .suspend        = twl4030_wdt_suspend,
 252         .resume         = twl4030_wdt_resume,
 253         .driver         = {
 254                 .owner  = THIS_MODULE,
 255                 .name   = "twl4030_wdt",
 256         },
 257 };
 258
 259 module_platform_driver(twl4030_wdt_driver);
 260
 261 MODULE_AUTHOR("Nokia Corporation");
 262 MODULE_LICENSE("GPL");
 263 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 264 MODULE_ALIAS("platform:twl4030_wdt");
 265