release/src-rt-6.x.4708/linux/linux-2.6.36/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 #include <linux/module.h>
  27 #include <linux/fs.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/timer.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/io.h>
  33 #include <mach/hardware.h>
  34
  35 #define WDT_VERSION     "0.3"
  36 #define PFX             "ep93xx_wdt: "
  37
  38 /* default timeout (secs) */
  39 #define WDT_TIMEOUT 30
  40
  41 static int nowayout = WATCHDOG_NOWAYOUT;
  42 static int timeout = WDT_TIMEOUT;
  43
  44 static struct timer_list timer;
  45 static unsigned long next_heartbeat;
  46 static unsigned long wdt_status;
  47 static unsigned long boot_status;
  48
  49 #define WDT_IN_USE              0
  50 #define WDT_OK_TO_CLOSE         1
  51
  52 #define EP93XX_WDT_REG(x)       (EP93XX_WATCHDOG_BASE + (x))
  53 #define EP93XX_WDT_WATCHDOG     EP93XX_WDT_REG(0x00)
  54 #define EP93XX_WDT_WDSTATUS     EP93XX_WDT_REG(0x04)
  55
  56 /* reset the wdt every ~200ms */
  57 #define WDT_INTERVAL (HZ/5)
  58
  59 static void wdt_enable(void)
  60 {
  61         __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
  62 }
  63
  64 static void wdt_disable(void)
  65 {
  66         __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
  67 }
  68
  69 static inline void wdt_ping(void)
  70 {
  71         __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
  72 }
  73
  74 static void wdt_startup(void)
  75 {
  76         next_heartbeat = jiffies + (timeout * HZ);
  77
  78         wdt_enable();
  79         mod_timer(&timer, jiffies + WDT_INTERVAL);
  80 }
  81
  82 static void wdt_shutdown(void)
  83 {
  84         del_timer_sync(&timer);
  85         wdt_disable();
  86 }
  87
  88 static void wdt_keepalive(void)
  89 {
  90         /* user land ping */
  91         next_heartbeat = jiffies + (timeout * HZ);
  92 }
  93
  94 static int ep93xx_wdt_open(struct inode *inode, struct file *file)
  95 {
  96         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  97                 return -EBUSY;
  98
  99         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 100
 101         wdt_startup();
 102
 103         return nonseekable_open(inode, file);
 104 }
 105
 106 static ssize_t
 107 ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
 108                  loff_t *ppos)
 109 {
 110         if (len) {
 111                 if (!nowayout) {
 112                         size_t i;
 113
 114                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 115
 116                         for (i = 0; i != len; i++) {
 117                                 char c;
 118
 119                                 if (get_user(c, data + i))
 120                                         return -EFAULT;
 121
 122                                 if (c == 'V')
 123                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 124                                 else
 125                                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 126                         }
 127                 }
 128                 wdt_keepalive();
 129         }
 130
 131         return len;
 132 }
 133
 134 static const struct watchdog_info ident = {
 135         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
 136         .identity = "EP93xx Watchdog",
 137 };
 138
 139 static long ep93xx_wdt_ioctl(struct file *file,
 140                                         unsigned int cmd, unsigned long arg)
 141 {
 142         int ret = -ENOTTY;
 143
 144         switch (cmd) {
 145         case WDIOC_GETSUPPORT:
 146                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 147                                 sizeof(ident)) ? -EFAULT : 0;
 148                 break;
 149
 150         case WDIOC_GETSTATUS:
 151                 ret = put_user(0, (int __user *)arg);
 152                 break;
 153
 154         case WDIOC_GETBOOTSTATUS:
 155                 ret = put_user(boot_status, (int __user *)arg);
 156                 break;
 157
 158         case WDIOC_KEEPALIVE:
 159                 wdt_keepalive();
 160                 ret = 0;
 161                 break;
 162
 163         case WDIOC_GETTIMEOUT:
 164                 /* actually, it is 0.250 seconds.... */
 165                 ret = put_user(1, (int __user *)arg);
 166                 break;
 167         }
 168         return ret;
 169 }
 170
 171 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
 172 {
 173         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 174                 wdt_shutdown();
 175         else
 176                 printk(KERN_CRIT PFX
 177                         "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 };
 192
 193 static struct miscdevice ep93xx_wdt_miscdev = {
 194         .minor          = WATCHDOG_MINOR,
 195         .name           = "watchdog",
 196         .fops           = &ep93xx_wdt_fops,
 197 };
 198
 199 static void ep93xx_timer_ping(unsigned long data)
 200 {
 201         if (time_before(jiffies, next_heartbeat))
 202                 wdt_ping();
 203
 204         /* Re-set the timer interval */
 205         mod_timer(&timer, jiffies + WDT_INTERVAL);
 206 }
 207
 208 static int __init ep93xx_wdt_init(void)
 209 {
 210         int err;
 211
 212         err = misc_register(&ep93xx_wdt_miscdev);
 213
 214         boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
 215
 216         printk(KERN_INFO PFX "EP93XX watchdog, driver version "
 217                 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                 printk(KERN_INFO PFX
 224                         "timeout value must be 1<=x<=3600, using %d\n",
 225                         timeout);
 226         }
 227
 228         setup_timer(&timer, ep93xx_timer_ping, 1);
 229         return err;
 230 }
 231
 232 static void __exit ep93xx_wdt_exit(void)
 233 {
 234         wdt_shutdown();
 235         misc_deregister(&ep93xx_wdt_miscdev);
 236 }
 237
 238 module_init(ep93xx_wdt_init);
 239 module_exit(ep93xx_wdt_exit);
 240
 241 module_param(nowayout, int, 0);
 242 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 243
 244 module_param(timeout, int, 0);
 245 MODULE_PARM_DESC(timeout,
 246         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 247                                 __MODULE_STRING(WDT_TIMEOUT) ")");
 248
 249 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
 250                 "Alessandro Zummo <a.zummo@towertech.it>");
 251 MODULE_DESCRIPTION("EP93xx Watchdog");
 252 MODULE_LICENSE("GPL");
 253 MODULE_VERSION(WDT_VERSION);
 254 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);