target/linux/adm5120/files/drivers/char/watchdog/adm5120_wdt.c

   1 /*
   2  *      ADM5120_WDT 0.01: Infineon ADM5120 SoC watchdog driver
   3  *      Copyright (c) Ondrej Zajicek <santiago@crfreenet.org>, 2007
   4  *
   5  *      based on
   6  *
   7  *      RC32434_WDT 0.01: IDT Interprise 79RC32434 watchdog driver
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/types.h>
  18 #include <linux/fs.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/watchdog.h>
  21
  22 #include <asm/bootinfo.h>
  23
  24 #include <adm5120_info.h>
  25 #include <adm5120_defs.h>
  26 #include <adm5120_irq.h>
  27 #include <adm5120_switch.h>
  28
  29
  30 #define DEFAULT_TIMEOUT 15              /* (secs) Default is 15 seconds */
  31 #define MAX_TIMEOUT     327
  32 /* Max is 327 seconds, counter is 15-bit integer, step is 10 ms */
  33
  34 #define NAME "adm5120_wdt"
  35 #define VERSION "0.1"
  36
  37 static int expect_close = 0;
  38 static int access = 0;
  39 static unsigned int timeout = DEFAULT_TIMEOUT;
  40
  41 static int nowayout = WATCHDOG_NOWAYOUT;
  42 module_param(nowayout, int, 0);
  43 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  44 MODULE_LICENSE("GPL");
  45
  46
  47 static inline void wdt_set_timeout(void)
  48 {
  49         u32 val = (1 << 31) | (((timeout * 100) & 0x7FFF) << 16);
  50         SW_WRITE_REG(SWITCH_REG_WDOG0, val);
  51 }
  52
  53 /*
  54    It looks like WDOG0-register-write don't modify counter,
  55    but WDOG0-register-read resets counter.
  56 */
  57
  58 static inline void wdt_reset_counter(void)
  59 {
  60         SW_READ_REG(SWITCH_REG_WDOG0);
  61 }
  62
  63 static inline void wdt_disable(void)
  64 {
  65         SW_WRITE_REG(SWITCH_REG_WDOG0, 0x7FFF0000);
  66 }
  67
  68
  69
  70 static int wdt_open(struct inode *inode, struct file *file)
  71 {
  72         /* Allow only one person to hold it open */
  73         if (access)
  74                 return -EBUSY;
  75
  76         if (nowayout) {
  77                 __module_get(THIS_MODULE);
  78         }
  79
  80         /* Activate timer */
  81         wdt_reset_counter();
  82         wdt_set_timeout();
  83         printk(KERN_INFO NAME ": enabling watchdog timer\n");
  84         access = 1;
  85         return 0;
  86 }
  87
  88 static int wdt_release(struct inode *inode, struct file *file)
  89 {
  90         /*
  91          *      Shut off the timer.
  92          *      Lock it in if it's a module and we set nowayout
  93          */
  94         if (expect_close && (nowayout == 0)) {
  95                 wdt_disable();
  96                 printk(KERN_INFO NAME ": disabling watchdog timer\n");
  97                 module_put(THIS_MODULE);
  98         } else {
  99                 printk(KERN_CRIT NAME ": device closed unexpectedly.  WDT will not stop!\n");
 100         }
 101         access = 0;
 102         return 0;
 103 }
 104
 105 static ssize_t wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
 106 {
 107         /* Refresh the timer. */
 108         if (len) {
 109                 if (!nowayout) {
 110                         size_t i;
 111
 112                         /* In case it was set long ago */
 113                         expect_close = 0;
 114
 115                         for (i = 0; i != len; i++) {
 116                                 char c;
 117                                 if (get_user(c, data + i))
 118                                         return -EFAULT;
 119                                 if (c == 'V')
 120                                         expect_close = 1;
 121                         }
 122                 }
 123                 wdt_reset_counter();
 124                 return len;
 125         }
 126         return 0;
 127 }
 128
 129 static int wdt_ioctl(struct inode *inode, struct file *file,
 130         unsigned int cmd, unsigned long arg)
 131 {
 132         int new_timeout;
 133         static struct watchdog_info ident = {
 134                 .options =              WDIOF_SETTIMEOUT |
 135                                         WDIOF_KEEPALIVEPING |
 136                                         WDIOF_MAGICCLOSE,
 137                 .firmware_version =     0,
 138                 .identity =             "ADM5120_WDT Watchdog",
 139         };
 140         switch (cmd) {
 141                 default:
 142                         return -ENOTTY;
 143                 case WDIOC_GETSUPPORT:
 144                         if(copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
 145                                 return -EFAULT;
 146                         return 0;
 147                 case WDIOC_GETSTATUS:
 148                 case WDIOC_GETBOOTSTATUS:
 149                         return put_user(0,(int *)arg);
 150                 case WDIOC_KEEPALIVE:
 151                         wdt_reset_counter();
 152                         return 0;
 153                 case WDIOC_SETTIMEOUT:
 154                         if (get_user(new_timeout, (int *)arg))
 155                                 return -EFAULT;
 156                         if (new_timeout < 1)
 157                                 return -EINVAL;
 158                         if (new_timeout > MAX_TIMEOUT)
 159                                 return -EINVAL;
 160                         timeout = new_timeout;
 161                         wdt_set_timeout();
 162                         /* Fall */
 163                 case WDIOC_GETTIMEOUT:
 164                         return put_user(timeout, (int *)arg);
 165         }
 166 }
 167
 168 static struct file_operations wdt_fops = {
 169         owner:          THIS_MODULE,
 170         llseek:         no_llseek,
 171         write:          wdt_write,
 172         ioctl:          wdt_ioctl,
 173         open:           wdt_open,
 174         release:        wdt_release,
 175 };
 176
 177 static struct miscdevice wdt_miscdev = {
 178         minor:          WATCHDOG_MINOR,
 179         name:           "watchdog",
 180         fops:           &wdt_fops,
 181 };
 182
 183 static char banner[] __initdata = KERN_INFO NAME ": Watchdog Timer version " VERSION "\n";
 184
 185 static int __init watchdog_init(void)
 186 {
 187         int ret;
 188
 189         /* There should be check for ADM5120 */
 190         if (mips_machgroup != MACH_GROUP_ADM5120)
 191                 return -1;
 192
 193         ret = misc_register(&wdt_miscdev);
 194
 195         if (ret)
 196                 return ret;
 197
 198         wdt_disable();
 199         printk(banner);
 200
 201         return 0;
 202 }
 203
 204 static void __exit watchdog_exit(void)
 205 {
 206         misc_deregister(&wdt_miscdev);
 207 }
 208
 209 module_init(watchdog_init);
 210 module_exit(watchdog_exit);