drivers/watchdog/ep93xx_wdt.c

   1 /*
   2  * Watchdog driver for Cirrus Logic EP93xx family of devices.
   3  *
   4  * Copyright (c) 2004 Ray Lehtiniemi
   5  * Copyright (c) 2006 Tower Technologies
   6  * Based on ep93xx driver, bits from alim7101_wdt.c
   7  *
   8  * Authors: Ray Lehtiniemi <rayl@mail.com>,
   9  *      Alessandro Zummo <a.zummo@towertech.it>
  10  *
  11  * This file is licensed under the terms of the GNU General Public
  12  * License version 2. This program is licensed "as is" without any
  13  * warranty of any kind, whether express or implied.
  14  *
  15  * This watchdog fires after 250msec, which is a too short interval
  16  * for us to rely on the user space daemon alone. So we ping the
  17  * wdt each ~200msec and eventually stop doing it if the user space
  18  * daemon dies.
  19  *
  20  * TODO:
  21  *
  22  *      - Test last reset from watchdog status
  23  *      - Add a few missing ioctls
  24  */
  25
  26 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  27
  28 #include <linux/module.h>
  29 #include <linux/fs.h>
  30 #include <linux/miscdevice.h>
  31 #include <linux/watchdog.h>
  32 #include <linux/timer.h>
  33 #include <linux/uaccess.h>
  34 #include <linux/io.h>
  35 #include <mach/hardware.h>
  36
  37 #define WDT_VERSION     "0.3"
  38
  39 /* default timeout (secs) */
  40 #define WDT_TIMEOUT 30
  41
  42 static int nowayout = WATCHDOG_NOWAYOUT;
  43 static int timeout = WDT_TIMEOUT;
  44
  45 static struct timer_list timer;
  46 static unsigned long next_heartbeat;
  47 static unsigned long wdt_status;
  48 static unsigned long boot_status;
  49
  50 #define WDT_IN_USE              0
  51 #define WDT_OK_TO_CLOSE         1
  52
  53 #define EP93XX_WDT_REG(x)       (EP93XX_WATCHDOG_BASE + (x))
  54 #define EP93XX_WDT_WATCHDOG     EP93XX_WDT_REG(0x00)
  55 #define EP93XX_WDT_WDSTATUS     EP93XX_WDT_REG(0x04)
  56
  57 /* reset the wdt every ~200ms */
  58 #define WDT_INTERVAL (HZ/5)
  59
  60 static void wdt_enable(void)
  61 {
  62         __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
  63 }
  64
  65 static void wdt_disable(void)
  66 {
  67         __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
  68 }
  69
  70 static inline void wdt_ping(void)
  71 {
  72         __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
  73 }
  74
  75 static void wdt_startup(void)
  76 {
  77         next_heartbeat = jiffies + (timeout * HZ);
  78
  79         wdt_enable();
  80         mod_timer(&timer, jiffies + WDT_INTERVAL);
  81 }
  82
  83 static void wdt_shutdown(void)
  84 {
  85         del_timer_sync(&timer);
  86         wdt_disable();
  87 }
  88
  89 static void wdt_keepalive(void)
  90 {
  91         /* user land ping */
  92         next_heartbeat = jiffies + (timeout * HZ);
  93 }
  94
  95 static int ep93xx_wdt_open(struct inode *inode, struct file *file)
  96 {
  97         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  98                 return -EBUSY;
  99
 100         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 101
 102         wdt_startup();
 103
 104         return nonseekable_open(inode, file);
 105 }
 106
 107 static ssize_t
 108 ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
 109                  loff_t *ppos)
 110 {
 111         if (len) {
 112                 if (!nowayout) {
 113                         size_t i;
 114
 115                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 116
 117                         for (i = 0; i != len; i++) {
 118                                 char c;
 119
 120                                 if (get_user(c, data + i))
 121                                         return -EFAULT;
 122
 123                                 if (c == 'V')
 124                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 125                                 else
 126                                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 127                         }
 128                 }
 129                 wdt_keepalive();
 130         }
 131
 132         return len;
 133 }
 134
 135 static const struct watchdog_info ident = {
 136         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
 137         .identity = "EP93xx Watchdog",
 138 };
 139
 140 static long ep93xx_wdt_ioctl(struct file *file,
 141                                         unsigned int cmd, unsigned long arg)
 142 {
 143         int ret = -ENOTTY;
 144
 145         switch (cmd) {
 146         case WDIOC_GETSUPPORT:
 147                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 148                                 sizeof(ident)) ? -EFAULT : 0;
 149                 break;
 150
 151         case WDIOC_GETSTATUS:
 152                 ret = put_user(0, (int __user *)arg);
 153                 break;
 154
 155         case WDIOC_GETBOOTSTATUS:
 156                 ret = put_user(boot_status, (int __user *)arg);
 157                 break;
 158
 159         case WDIOC_KEEPALIVE:
 160                 wdt_keepalive();
 161                 ret = 0;
 162                 break;
 163
 164         case WDIOC_GETTIMEOUT:
 165                 /* actually, it is 0.250 seconds.... */
 166                 ret = put_user(1, (int __user *)arg);
 167                 break;
 168         }
 169         return ret;
 170 }
 171
 172 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
 173 {
 174         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 175                 wdt_shutdown();
 176         else
 177                 pr_crit("Device closed unexpectedly - timer will not stop\n");
 178
 179         clear_bit(WDT_IN_USE, &wdt_status);
 180         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 181
 182         return 0;
 183 }
 184
 185 static const struct file_operations ep93xx_wdt_fops = {
 186         .owner          = THIS_MODULE,
 187         .write          = ep93xx_wdt_write,
 188         .unlocked_ioctl = ep93xx_wdt_ioctl,
 189         .open           = ep93xx_wdt_open,
 190         .release        = ep93xx_wdt_release,
 191         .llseek         = no_llseek,
 192 };
 193
 194 static struct miscdevice ep93xx_wdt_miscdev = {
 195         .minor          = WATCHDOG_MINOR,
 196         .name           = "watchdog",
 197         .fops           = &ep93xx_wdt_fops,
 198 };
 199
 200 static void ep93xx_timer_ping(unsigned long data)
 201 {
 202         if (time_before(jiffies, next_heartbeat))
 203                 wdt_ping();
 204
 205         /* Re-set the timer interval */
 206         mod_timer(&timer, jiffies + WDT_INTERVAL);
 207 }
 208
 209 static int __init ep93xx_wdt_init(void)
 210 {
 211         int err;
 212
 213         err = misc_register(&ep93xx_wdt_miscdev);
 214
 215         boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
 216
 217         pr_info("EP93XX watchdog, driver version " WDT_VERSION "%s\n",
 218                 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
 219                 ? " (nCS1 disable detected)" : "");
 220
 221         if (timeout < 1 || timeout > 3600) {
 222                 timeout = WDT_TIMEOUT;
 223                 pr_info("timeout value must be 1<=x<=3600, using %d\n",
 224                         timeout);
 225         }
 226
 227         setup_timer(&timer, ep93xx_timer_ping, 1);
 228         return err;
 229 }
 230
 231 static void __exit ep93xx_wdt_exit(void)
 232 {
 233         wdt_shutdown();
 234         misc_deregister(&ep93xx_wdt_miscdev);
 235 }
 236
 237 module_init(ep93xx_wdt_init);
 238 module_exit(ep93xx_wdt_exit);
 239
 240 module_param(nowayout, int, 0);
 241 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 242
 243 module_param(timeout, int, 0);
 244 MODULE_PARM_DESC(timeout,
 245         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 246                                 __MODULE_STRING(WDT_TIMEOUT) ")");
 247
 248 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
 249                 "Alessandro Zummo <a.zummo@towertech.it>");
 250 MODULE_DESCRIPTION("EP93xx Watchdog");
 251 MODULE_LICENSE("GPL");
 252 MODULE_VERSION(WDT_VERSION);
 253 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);