drivers/char/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
  32 #include <asm/hardware.h>
  33 #include <asm/uaccess.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         /* Can't seek (pwrite) on this device */
 111         if (*ppos != file->f_pos)
 112                 return -ESPIPE;
 113
 114         if (len) {
 115                 if (!nowayout) {
 116                         size_t i;
 117
 118                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 119
 120                         for (i = 0; i != len; i++) {
 121                                 char c;
 122
 123                                 if (get_user(c, data + i))
 124                                         return -EFAULT;
 125
 126                                 if (c == 'V')
 127                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 128                                 else
 129                                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 130                         }
 131                 }
 132                 wdt_keepalive();
 133         }
 134
 135         return len;
 136 }
 137
 138 static struct watchdog_info ident = {
 139         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
 140         .identity = "EP93xx Watchdog",
 141 };
 142
 143 static int
 144 ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 145                  unsigned long arg)
 146 {
 147         int ret = -ENOIOCTLCMD;
 148
 149         switch (cmd) {
 150         case WDIOC_GETSUPPORT:
 151                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 152                                 sizeof(ident)) ? -EFAULT : 0;
 153                 break;
 154
 155         case WDIOC_GETSTATUS:
 156                 ret = put_user(0, (int __user *)arg);
 157                 break;
 158
 159         case WDIOC_GETBOOTSTATUS:
 160                 ret = put_user(boot_status, (int __user *)arg);
 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         case WDIOC_KEEPALIVE:
 169                 wdt_keepalive();
 170                 ret = 0;
 171                 break;
 172         }
 173         return ret;
 174 }
 175
 176 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
 177 {
 178         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 179                 wdt_shutdown();
 180         else
 181                 printk(KERN_CRIT PFX "Device closed unexpectedly - "
 182                         "timer will not stop\n");
 183
 184         clear_bit(WDT_IN_USE, &wdt_status);
 185         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 186
 187         return 0;
 188 }
 189
 190 static const struct file_operations ep93xx_wdt_fops = {
 191         .owner          = THIS_MODULE,
 192         .write          = ep93xx_wdt_write,
 193         .ioctl          = ep93xx_wdt_ioctl,
 194         .open           = ep93xx_wdt_open,
 195         .release        = ep93xx_wdt_release,
 196 };
 197
 198 static struct miscdevice ep93xx_wdt_miscdev = {
 199         .minor          = WATCHDOG_MINOR,
 200         .name           = "watchdog",
 201         .fops           = &ep93xx_wdt_fops,
 202 };
 203
 204 static void ep93xx_timer_ping(unsigned long data)
 205 {
 206         if (time_before(jiffies, next_heartbeat))
 207                 wdt_ping();
 208
 209         /* Re-set the timer interval */
 210         mod_timer(&timer, jiffies + WDT_INTERVAL);
 211 }
 212
 213 static int __init ep93xx_wdt_init(void)
 214 {
 215         int err;
 216
 217         err = misc_register(&ep93xx_wdt_miscdev);
 218
 219         boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
 220
 221         printk(KERN_INFO PFX "EP93XX watchdog, driver version "
 222                 WDT_VERSION "%s\n",
 223                 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
 224                 ? " (nCS1 disable detected)" : "");
 225
 226         if (timeout < 1 || timeout > 3600) {
 227                 timeout = WDT_TIMEOUT;
 228                 printk(KERN_INFO PFX
 229                         "timeout value must be 1<=x<=3600, using %d\n",
 230                         timeout);
 231         }
 232
 233         setup_timer(&timer, ep93xx_timer_ping, 1);
 234         return err;
 235 }
 236
 237 static void __exit ep93xx_wdt_exit(void)
 238 {
 239         wdt_shutdown();
 240         misc_deregister(&ep93xx_wdt_miscdev);
 241 }
 242
 243 module_init(ep93xx_wdt_init);
 244 module_exit(ep93xx_wdt_exit);
 245
 246 module_param(nowayout, int, 0);
 247 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 248
 249 module_param(timeout, int, 0);
 250 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 251
 252 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
 253                 "Alessandro Zummo <a.zummo@towertech.it>");
 254 MODULE_DESCRIPTION("EP93xx Watchdog");
 255 MODULE_LICENSE("GPL");
 256 MODULE_VERSION(WDT_VERSION);
 257 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);