drivers/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 <galak@kernel.crashing.org>
   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/module.h>
  18 #include <linux/fs.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/notifier.h>
  21 #include <linux/watchdog.h>
  22
  23 #include <asm/reg_booke.h>
  24 #include <asm/uaccess.h>
  25 #include <asm/system.h>
  26
  27 /* If the kernel parameter wdt=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 3    /* Refer to the PPC40x and PPC4xx manuals */
  39 #endif                          /* for timing information */
  40
  41 u32 booke_wdt_enabled = 0;
  42 u32 booke_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_ping:
  52  */
  53 static __inline__ void booke_wdt_ping(void)
  54 {
  55         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  56 }
  57
  58 /*
  59  * booke_wdt_enable:
  60  */
  61 static __inline__ void booke_wdt_enable(void)
  62 {
  63         u32 val;
  64
  65         /* clear status before enabling watchdog */
  66         booke_wdt_ping();
  67         val = mfspr(SPRN_TCR);
  68         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
  69
  70         mtspr(SPRN_TCR, val);
  71 }
  72
  73 /*
  74  * booke_wdt_write:
  75  */
  76 static ssize_t booke_wdt_write (struct file *file, const char __user *buf,
  77                                 size_t count, loff_t *ppos)
  78 {
  79         booke_wdt_ping();
  80         return count;
  81 }
  82
  83 static struct watchdog_info ident = {
  84   .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  85   .firmware_version = 0,
  86   .identity = "PowerPC Book-E Watchdog",
  87 };
  88
  89 /*
  90  * booke_wdt_ioctl:
  91  */
  92 static int booke_wdt_ioctl (struct inode *inode, struct file *file,
  93                             unsigned int cmd, unsigned long arg)
  94 {
  95         u32 tmp = 0;
  96         u32 __user *p = (u32 __user *)arg;
  97
  98         switch (cmd) {
  99         case WDIOC_GETSUPPORT:
 100                 if (copy_to_user ((struct watchdog_info __user *) arg, &ident,
 101                                 sizeof(struct watchdog_info)))
 102                         return -EFAULT;
 103         case WDIOC_GETSTATUS:
 104                 return put_user(ident.options, p);
 105         case WDIOC_GETBOOTSTATUS:
 106                 /* XXX: something is clearing TSR */
 107                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 108                 /* returns 1 if last reset was caused by the WDT */
 109                 return (tmp ? 1 : 0);
 110         case WDIOC_KEEPALIVE:
 111                 booke_wdt_ping();
 112                 return 0;
 113         case WDIOC_SETTIMEOUT:
 114                 if (get_user(booke_wdt_period, p))
 115                         return -EFAULT;
 116                 mtspr(SPRN_TCR, (mfspr(SPRN_TCR)&~WDTP(0))|WDTP(booke_wdt_period));
 117                 return 0;
 118         case WDIOC_GETTIMEOUT:
 119                 return put_user(booke_wdt_period, p);
 120         case WDIOC_SETOPTIONS:
 121                 if (get_user(tmp, p))
 122                         return -EINVAL;
 123                 if (tmp == WDIOS_ENABLECARD) {
 124                         booke_wdt_ping();
 125                         break;
 126                 } else
 127                         return -EINVAL;
 128                 return 0;
 129         default:
 130                 return -ENOTTY;
 131         }
 132
 133         return 0;
 134 }
 135 /*
 136  * booke_wdt_open:
 137  */
 138 static int booke_wdt_open (struct inode *inode, struct file *file)
 139 {
 140         if (booke_wdt_enabled == 0) {
 141                 booke_wdt_enabled = 1;
 142                 booke_wdt_enable();
 143                 printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 144                                 booke_wdt_period);
 145         }
 146
 147         return nonseekable_open(inode, file);
 148 }
 149
 150 static const struct file_operations booke_wdt_fops = {
 151   .owner = THIS_MODULE,
 152   .llseek = no_llseek,
 153   .write = booke_wdt_write,
 154   .ioctl = booke_wdt_ioctl,
 155   .open = booke_wdt_open,
 156 };
 157
 158 static struct miscdevice booke_wdt_miscdev = {
 159   .minor = WATCHDOG_MINOR,
 160   .name = "watchdog",
 161   .fops = &booke_wdt_fops,
 162 };
 163
 164 static void __exit booke_wdt_exit(void)
 165 {
 166         misc_deregister(&booke_wdt_miscdev);
 167 }
 168
 169 /*
 170  * booke_wdt_init:
 171  */
 172 static int __init booke_wdt_init(void)
 173 {
 174         int ret = 0;
 175
 176         printk (KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 177         ident.firmware_version = cur_cpu_spec->pvr_value;
 178
 179         ret = misc_register(&booke_wdt_miscdev);
 180         if (ret) {
 181                 printk (KERN_CRIT "Cannot register miscdev on minor=%d (err=%d)\n",
 182                                 WATCHDOG_MINOR, ret);
 183                 return ret;
 184         }
 185
 186         if (booke_wdt_enabled == 1) {
 187                 printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 188                                 booke_wdt_period);
 189                 booke_wdt_enable();
 190         }
 191
 192         return ret;
 193 }
 194 device_initcall(booke_wdt_init);