drivers/char/watchdog/booke_wdt.c

   1 /*
   2  * drivers/char/watchdog/booke_wdt.c
   3  *
   4  * Watchdog timer for PowerPC Book-E systems
   5  *
   6  * Author: Matthew McClintock
   7  * Maintainer: Kumar Gala <kumar.gala@freescale.com>
   8  *
   9  * Copyright 2005 Freescale Semiconductor Inc.
  10  *
  11  * This program is free software; you can redistribute  it and/or modify it
  12  * under  the terms of  the GNU General  Public License as published by the
  13  * Free Software Foundation;  either version 2 of the  License, or (at your
  14  * option) any later version.
  15  */
  16
  17 #include <linux/config.h>
  18 #include <linux/module.h>
  19 #include <linux/fs.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/notifier.h>
  22 #include <linux/watchdog.h>
  23
  24 #include <asm/reg_booke.h>
  25 #include <asm/uaccess.h>
  26
  27 /* If the kernel parameter wdt_enable=1, the watchdog will be enabled at boot.
  28  * Also, the wdt_period sets the watchdog timer period timeout.
  29  * For E500 cpus the wdt_period sets which bit changing from 0->1 will
  30  * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
  31  * first time nothing will happen, the second time a watchdog exception will
  32  * occur, and the final time the board will reset.
  33  */
  34
  35 #ifdef  CONFIG_FSL_BOOKE
  36 #define WDT_PERIOD_DEFAULT 63   /* Ex. wdt_period=28 bus=333Mhz , reset=~40sec */
  37 #else
  38 #define WDT_PERIOD_DEFAULT 4    /* Refer to the PPC40x and PPC4xx manuals */
  39 #endif                          /* for timing information */
  40
  41 u32 wdt_enable = 0;
  42 u32 wdt_period = WDT_PERIOD_DEFAULT;
  43
  44 #ifdef  CONFIG_FSL_BOOKE
  45 #define WDTP(x)         ((((63-x)&0x3)<<30)|(((63-x)&0x3c)<<15))
  46 #else
  47 #define WDTP(x)         (TCR_WP(x))
  48 #endif
  49
  50 /*
  51  * booke_wdt_enable:
  52  */
  53 static __inline__ void booke_wdt_enable(void)
  54 {
  55         u32 val;
  56
  57         val = mfspr(SPRN_TCR);
  58         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(wdt_period));
  59
  60         mtspr(SPRN_TCR, val);
  61 }
  62
  63 /*
  64  * booke_wdt_ping:
  65  */
  66 static __inline__ void booke_wdt_ping(void)
  67 {
  68         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  69 }
  70
  71 /*
  72  * booke_wdt_write:
  73  */
  74 static ssize_t booke_wdt_write (struct file *file, const char *buf,
  75                                 size_t count, loff_t *ppos)
  76 {
  77         booke_wdt_ping();
  78         return count;
  79 }
  80
  81 static struct watchdog_info ident = {
  82   .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  83   .firmware_version = 0,
  84   .identity = "PowerPC Book-E Watchdog",
  85 };
  86
  87 /*
  88  * booke_wdt_ioctl:
  89  */
  90 static int booke_wdt_ioctl (struct inode *inode, struct file *file,
  91                             unsigned int cmd, unsigned long arg)
  92 {
  93         u32 tmp = 0;
  94
  95         switch (cmd) {
  96         case WDIOC_GETSUPPORT:
  97                 if (copy_to_user ((struct watchdog_info *) arg, &ident,
  98                                 sizeof(struct watchdog_info)))
  99                         return -EFAULT;
 100         case WDIOC_GETSTATUS:
 101                 return put_user(ident.options, (u32 *) arg);
 102         case WDIOC_GETBOOTSTATUS:
 103                 /* XXX: something is clearing TSR */
 104                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 105                 /* returns 1 if last reset was caused by the WDT */
 106                 return (tmp ? 1 : 0);
 107         case WDIOC_KEEPALIVE:
 108                 booke_wdt_ping();
 109                 return 0;
 110         case WDIOC_SETTIMEOUT:
 111                 if (get_user(wdt_period, (u32 *) arg))
 112                         return -EFAULT;
 113                 mtspr(SPRN_TCR, (mfspr(SPRN_TCR)&~WDTP(0))|WDTP(wdt_period));
 114                 return 0;
 115         case WDIOC_GETTIMEOUT:
 116                 return put_user(wdt_period, (u32 *) arg);
 117         case WDIOC_SETOPTIONS:
 118                 if (get_user(tmp, (u32 *) arg))
 119                         return -EINVAL;
 120                 if (tmp == WDIOS_ENABLECARD) {
 121                         booke_wdt_ping();
 122                         break;
 123                 } else
 124                         return -EINVAL;
 125                 return 0;
 126         default:
 127                 return -ENOIOCTLCMD;
 128         }
 129
 130         return 0;
 131 }
 132 /*
 133  * booke_wdt_open:
 134  */
 135 static int booke_wdt_open (struct inode *inode, struct file *file)
 136 {
 137         if (wdt_enable == 0) {
 138                 wdt_enable = 1;
 139                 booke_wdt_enable();
 140                 printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 141                                 wdt_period);
 142         }
 143
 144         return 0;
 145 }
 146
 147 static struct file_operations booke_wdt_fops = {
 148   .owner = THIS_MODULE,
 149   .llseek = no_llseek,
 150   .write = booke_wdt_write,
 151   .ioctl = booke_wdt_ioctl,
 152   .open = booke_wdt_open,
 153 };
 154
 155 static struct miscdevice booke_wdt_miscdev = {
 156   .minor = WATCHDOG_MINOR,
 157   .name = "watchdog",
 158   .fops = &booke_wdt_fops,
 159 };
 160
 161 static void __exit booke_wdt_exit(void)
 162 {
 163         misc_deregister(&booke_wdt_miscdev);
 164 }
 165
 166 /*
 167  * booke_wdt_init:
 168  */
 169 static int __init booke_wdt_init(void)
 170 {
 171         int ret = 0;
 172
 173         printk (KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 174         ident.firmware_version = cpu_specs[0].pvr_value;
 175
 176         ret = misc_register(&booke_wdt_miscdev);
 177         if (ret) {
 178                 printk (KERN_CRIT "Cannot register miscdev on minor=%d (err=%d)\n",
 179                                 WATCHDOG_MINOR, ret);
 180                 return ret;
 181         }
 182
 183         if (wdt_enable == 1) {
 184                 printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 185                                 wdt_period);
 186                 booke_wdt_enable();
 187         }
 188
 189         return ret;
 190 }
 191 device_initcall(booke_wdt_init);