target/linux/adm5120/files-2.6.26/drivers/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 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/fs.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/watchdog.h>
  20 #include <linux/irq.h>
  21
  22 #include <asm/bootinfo.h>
  23
  24 #include <asm/mach-adm5120/adm5120_info.h>
  25 #include <asm/mach-adm5120/adm5120_defs.h>
  26 #include <asm/mach-adm5120/adm5120_switch.h>
  27
  28 #define DEFAULT_TIMEOUT 15              /* (secs) Default is 15 seconds */
  29 #define MAX_TIMEOUT     327
  30 /* Max is 327 seconds, counter is 15-bit integer, step is 10 ms */
  31
  32 #define NAME "adm5120_wdt"
  33 #define VERSION "0.1"
  34
  35 static int expect_close = 0;
  36 static int access = 0;
  37 static unsigned int timeout = DEFAULT_TIMEOUT;
  38
  39 static int nowayout = WATCHDOG_NOWAYOUT;
  40 module_param(nowayout, int, 0);
  41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  42 MODULE_LICENSE("GPL");
  43
  44
  45 static inline void wdt_set_timeout(void)
  46 {
  47         u32 val = (1 << 31) | (((timeout * 100) & 0x7FFF) << 16);
  48         SW_WRITE_REG(SWITCH_REG_WDOG0, val);
  49 }
  50
  51 /*
  52    It looks like WDOG0-register-write don't modify counter,
  53    but WDOG0-register-read resets counter.
  54 */
  55
  56 static inline void wdt_reset_counter(void)
  57 {
  58         SW_READ_REG(SWITCH_REG_WDOG0);
  59 }
  60
  61 static inline void wdt_disable(void)
  62 {
  63         SW_WRITE_REG(SWITCH_REG_WDOG0, 0x7FFF0000);
  64 }
  65
  66
  67
  68 static int wdt_open(struct inode *inode, struct file *file)
  69 {
  70         /* Allow only one person to hold it open */
  71         if (access)
  72                 return -EBUSY;
  73
  74         if (nowayout) {
  75                 __module_get(THIS_MODULE);
  76         }
  77
  78         /* Activate timer */
  79         wdt_reset_counter();
  80         wdt_set_timeout();
  81         printk(KERN_INFO NAME ": enabling watchdog timer\n");
  82         access = 1;
  83         return 0;
  84 }
  85
  86 static int wdt_release(struct inode *inode, struct file *file)
  87 {
  88         /*
  89          *      Shut off the timer.
  90          *      Lock it in if it's a module and we set nowayout
  91          */
  92         if (expect_close && (nowayout == 0)) {
  93                 wdt_disable();
  94                 printk(KERN_INFO NAME ": disabling watchdog timer\n");
  95                 module_put(THIS_MODULE);
  96         } else {
  97                 printk(KERN_CRIT NAME ": device closed unexpectedly.  WDT will not stop!\n");
  98         }
  99         access = 0;
 100         return 0;
 101 }
 102
 103 static ssize_t wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
 104 {
 105         /* Refresh the timer. */
 106         if (len) {
 107                 if (!nowayout) {
 108                         size_t i;
 109
 110                         /* In case it was set long ago */
 111                         expect_close = 0;
 112
 113                         for (i = 0; i != len; i++) {
 114                                 char c;
 115                                 if (get_user(c, data + i))
 116                                         return -EFAULT;
 117                                 if (c == 'V')
 118                                         expect_close = 1;
 119                         }
 120                 }
 121                 wdt_reset_counter();
 122                 return len;
 123         }
 124         return 0;
 125 }
 126
 127 static int wdt_ioctl(struct inode *inode, struct file *file,
 128         unsigned int cmd, unsigned long arg)
 129 {
 130         int new_timeout;
 131         static struct watchdog_info ident = {
 132                 .options =              WDIOF_SETTIMEOUT |
 133                                         WDIOF_KEEPALIVEPING |
 134                                         WDIOF_MAGICCLOSE,
 135                 .firmware_version =     0,
 136                 .identity =             "ADM5120_WDT Watchdog",
 137         };
 138         switch (cmd) {
 139                 default:
 140                         return -ENOTTY;
 141                 case WDIOC_GETSUPPORT:
 142                         if(copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
 143                                 return -EFAULT;
 144                         return 0;
 145                 case WDIOC_GETSTATUS:
 146                 case WDIOC_GETBOOTSTATUS:
 147                         return put_user(0,(int *)arg);
 148                 case WDIOC_KEEPALIVE:
 149                         wdt_reset_counter();
 150                         return 0;
 151                 case WDIOC_SETTIMEOUT:
 152                         if (get_user(new_timeout, (int *)arg))
 153                                 return -EFAULT;
 154                         if (new_timeout < 1)
 155                                 return -EINVAL;
 156                         if (new_timeout > MAX_TIMEOUT)
 157                                 return -EINVAL;
 158                         timeout = new_timeout;
 159                         wdt_set_timeout();
 160                         /* Fall */
 161                 case WDIOC_GETTIMEOUT:
 162                         return put_user(timeout, (int *)arg);
 163         }
 164 }
 165
 166 static struct file_operations wdt_fops = {
 167         owner:          THIS_MODULE,
 168         llseek:         no_llseek,
 169         write:          wdt_write,
 170         ioctl:          wdt_ioctl,
 171         open:           wdt_open,
 172         release:        wdt_release,
 173 };
 174
 175 static struct miscdevice wdt_miscdev = {
 176         minor:          WATCHDOG_MINOR,
 177         name:           "watchdog",
 178         fops:           &wdt_fops,
 179 };
 180
 181 static char banner[] __initdata = KERN_INFO NAME ": Watchdog Timer version " VERSION "\n";
 182
 183 static int __init watchdog_init(void)
 184 {
 185         int ret;
 186
 187         ret = misc_register(&wdt_miscdev);
 188
 189         if (ret)
 190                 return ret;
 191
 192         wdt_disable();
 193         printk(banner);
 194
 195         return 0;
 196 }
 197
 198 static void __exit watchdog_exit(void)
 199 {
 200         misc_deregister(&wdt_miscdev);
 201 }
 202
 203 module_init(watchdog_init);
 204 module_exit(watchdog_exit);