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 <mach/hardware.h>
  33
  34 #define WDT_VERSION     "0.3"
  35 #define PFX             "ep93xx_wdt: "
  36
  37 /* default timeout (secs) */
  38 #define WDT_TIMEOUT 30
  39
  40 static int nowayout = WATCHDOG_NOWAYOUT;
  41 static int timeout = WDT_TIMEOUT;
  42
  43 static struct timer_list timer;
  44 static unsigned long next_heartbeat;
  45 static unsigned long wdt_status;
  46 static unsigned long boot_status;
  47
  48 #define WDT_IN_USE              0
  49 #define WDT_OK_TO_CLOSE         1
  50
  51 #define EP93XX_WDT_REG(x)       (EP93XX_WATCHDOG_BASE + (x))
  52 #define EP93XX_WDT_WATCHDOG     EP93XX_WDT_REG(0x00)
  53 #define EP93XX_WDT_WDSTATUS     EP93XX_WDT_REG(0x04)
  54
  55 /* reset the wdt every ~200ms */
  56 #define WDT_INTERVAL (HZ/5)
  57
  58 static void wdt_enable(void)
  59 {
  60         __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
  61 }
  62
  63 static void wdt_disable(void)
  64 {
  65         __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
  66 }
  67
  68 static inline void wdt_ping(void)
  69 {
  70         __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
  71 }
  72
  73 static void wdt_startup(void)
  74 {
  75         next_heartbeat = jiffies + (timeout * HZ);
  76
  77         wdt_enable();
  78         mod_timer(&timer, jiffies + WDT_INTERVAL);
  79 }
  80
  81 static void wdt_shutdown(void)
  82 {
  83         del_timer_sync(&timer);
  84         wdt_disable();
  85 }
  86
  87 static void wdt_keepalive(void)
  88 {
  89         /* user land ping */
  90         next_heartbeat = jiffies + (timeout * HZ);
  91 }
  92
  93 static int ep93xx_wdt_open(struct inode *inode, struct file *file)
  94 {
  95         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  96                 return -EBUSY;
  97
  98         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  99
 100         wdt_startup();
 101
 102         return nonseekable_open(inode, file);
 103 }
 104
 105 static ssize_t
 106 ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
 107                  loff_t *ppos)
 108 {
 109         if (len) {
 110                 if (!nowayout) {
 111                         size_t i;
 112
 113                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 114
 115                         for (i = 0; i != len; i++) {
 116                                 char c;
 117
 118                                 if (get_user(c, data + i))
 119                                         return -EFAULT;
 120
 121                                 if (c == 'V')
 122                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 123                                 else
 124                                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 125                         }
 126                 }
 127                 wdt_keepalive();
 128         }
 129
 130         return len;
 131 }
 132
 133 static struct watchdog_info ident = {
 134         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
 135         .identity = "EP93xx Watchdog",
 136 };
 137
 138 static long ep93xx_wdt_ioctl(struct file *file,
 139                                         unsigned int cmd, unsigned long arg)
 140 {
 141         int ret = -ENOTTY;
 142
 143         switch (cmd) {
 144         case WDIOC_GETSUPPORT:
 145                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 146                                 sizeof(ident)) ? -EFAULT : 0;
 147                 break;
 148
 149         case WDIOC_GETSTATUS:
 150                 ret = put_user(0, (int __user *)arg);
 151                 break;
 152
 153         case WDIOC_GETBOOTSTATUS:
 154                 ret = put_user(boot_status, (int __user *)arg);
 155                 break;
 156
 157         case WDIOC_KEEPALIVE:
 158                 wdt_keepalive();
 159                 ret = 0;
 160                 break;
 161
 162         case WDIOC_GETTIMEOUT:
 163                 /* actually, it is 0.250 seconds.... */
 164                 ret = put_user(1, (int __user *)arg);
 165                 break;
 166         }
 167         return ret;
 168 }
 169
 170 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
 171 {
 172         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 173                 wdt_shutdown();
 174         else
 175                 printk(KERN_CRIT PFX
 176                         "Device closed unexpectedly - timer will not stop\n");
 177
 178         clear_bit(WDT_IN_USE, &wdt_status);
 179         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 180
 181         return 0;
 182 }
 183
 184 static const struct file_operations ep93xx_wdt_fops = {
 185         .owner          = THIS_MODULE,
 186         .write          = ep93xx_wdt_write,
 187         .unlocked_ioctl = ep93xx_wdt_ioctl,
 188         .open           = ep93xx_wdt_open,
 189         .release        = ep93xx_wdt_release,
 190 };
 191
 192 static struct miscdevice ep93xx_wdt_miscdev = {
 193         .minor          = WATCHDOG_MINOR,
 194         .name           = "watchdog",
 195         .fops           = &ep93xx_wdt_fops,
 196 };
 197
 198 static void ep93xx_timer_ping(unsigned long data)
 199 {
 200         if (time_before(jiffies, next_heartbeat))
 201                 wdt_ping();
 202
 203         /* Re-set the timer interval */
 204         mod_timer(&timer, jiffies + WDT_INTERVAL);
 205 }
 206
 207 static int __init ep93xx_wdt_init(void)
 208 {
 209         int err;
 210
 211         err = misc_register(&ep93xx_wdt_miscdev);
 212
 213         boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
 214
 215         printk(KERN_INFO PFX "EP93XX watchdog, driver version "
 216                 WDT_VERSION "%s\n",
 217                 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
 218                 ? " (nCS1 disable detected)" : "");
 219
 220         if (timeout < 1 || timeout > 3600) {
 221                 timeout = WDT_TIMEOUT;
 222                 printk(KERN_INFO PFX
 223                         "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(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);