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
  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         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 struct watchdog_info ident = {
 135         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
 136         .identity = "EP93xx Watchdog",
 137 };
 138
 139 static int
 140 ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 141                  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_GETTIMEOUT:
 160                 /* actually, it is 0.250 seconds.... */
 161                 ret = put_user(1, (int __user *)arg);
 162                 break;
 163
 164         case WDIOC_KEEPALIVE:
 165                 wdt_keepalive();
 166                 ret = 0;
 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                 printk(KERN_CRIT PFX "Device closed unexpectedly - "
 178                         "timer will not stop\n");
 179
 180         clear_bit(WDT_IN_USE, &wdt_status);
 181         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 182
 183         return 0;
 184 }
 185
 186 static const struct file_operations ep93xx_wdt_fops = {
 187         .owner          = THIS_MODULE,
 188         .write          = ep93xx_wdt_write,
 189         .ioctl          = ep93xx_wdt_ioctl,
 190         .open           = ep93xx_wdt_open,
 191         .release        = ep93xx_wdt_release,
 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         printk(KERN_INFO PFX "EP93XX watchdog, driver version "
 218                 WDT_VERSION "%s\n",
 219                 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
 220                 ? " (nCS1 disable detected)" : "");
 221
 222         if (timeout < 1 || timeout > 3600) {
 223                 timeout = WDT_TIMEOUT;
 224                 printk(KERN_INFO PFX
 225                         "timeout value must be 1<=x<=3600, using %d\n",
 226                         timeout);
 227         }
 228
 229         setup_timer(&timer, ep93xx_timer_ping, 1);
 230         return err;
 231 }
 232
 233 static void __exit ep93xx_wdt_exit(void)
 234 {
 235         wdt_shutdown();
 236         misc_deregister(&ep93xx_wdt_miscdev);
 237 }
 238
 239 module_init(ep93xx_wdt_init);
 240 module_exit(ep93xx_wdt_exit);
 241
 242 module_param(nowayout, int, 0);
 243 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 244
 245 module_param(timeout, int, 0);
 246 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_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);