drivers/watchdog/booke_wdt.c

   1 /*
   2  * Watchdog timer for PowerPC Book-E systems
   3  *
   4  * Author: Matthew McClintock
   5  * Maintainer: Kumar Gala <galak@kernel.crashing.org>
   6  *
   7  * Copyright 2005, 2008 Freescale Semiconductor Inc.
   8  *
   9  * This program is free software; you can redistribute  it and/or modify it
  10  * under  the terms of  the GNU General  Public License as published by the
  11  * Free Software Foundation;  either version 2 of the  License, or (at your
  12  * option) any later version.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/fs.h>
  17 #include <linux/smp.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/notifier.h>
  20 #include <linux/watchdog.h>
  21
  22 #include <asm/reg_booke.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/system.h>
  25
  26 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
  27  * Also, the wdt_period sets the watchdog timer period timeout.
  28  * For E500 cpus the wdt_period sets which bit changing from 0->1 will
  29  * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
  30  * first time nothing will happen, the second time a watchdog exception will
  31  * occur, and the final time the board will reset.
  32  */
  33
  34 #ifdef  CONFIG_FSL_BOOKE
  35 #define WDT_PERIOD_DEFAULT 63   /* Ex. wdt_period=28 bus=333Mhz , reset=~40sec */
  36 #else
  37 #define WDT_PERIOD_DEFAULT 3    /* Refer to the PPC40x and PPC4xx manuals */
  38 #endif                          /* for timing information */
  39
  40 u32 booke_wdt_enabled;
  41 u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
  42
  43 #ifdef  CONFIG_FSL_BOOKE
  44 #define WDTP(x)         ((((63-x)&0x3)<<30)|(((63-x)&0x3c)<<15))
  45 #else
  46 #define WDTP(x)         (TCR_WP(x))
  47 #endif
  48
  49 static DEFINE_SPINLOCK(booke_wdt_lock);
  50
  51 static void __booke_wdt_ping(void *data)
  52 {
  53         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  54 }
  55
  56 static void booke_wdt_ping(void)
  57 {
  58         on_each_cpu(__booke_wdt_ping, NULL, 0);
  59 }
  60
  61 static void __booke_wdt_enable(void *data)
  62 {
  63         u32 val;
  64
  65         /* clear status before enabling watchdog */
  66         __booke_wdt_ping(NULL);
  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 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
  74                                 size_t count, loff_t *ppos)
  75 {
  76         booke_wdt_ping();
  77         return count;
  78 }
  79
  80 static struct watchdog_info ident = {
  81         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  82         .identity = "PowerPC Book-E Watchdog",
  83 };
  84
  85 static int booke_wdt_ioctl(struct inode *inode, struct file *file,
  86                             unsigned int cmd, unsigned long arg)
  87 {
  88         u32 tmp = 0;
  89         u32 __user *p = (u32 __user *)arg;
  90
  91         switch (cmd) {
  92         case WDIOC_GETSUPPORT:
  93                 if (copy_to_user((struct watchdog_info __user *)arg, &ident,
  94                                 sizeof(struct watchdog_info)))
  95                         return -EFAULT;
  96         case WDIOC_GETSTATUS:
  97                 return put_user(ident.options, p);
  98         case WDIOC_GETBOOTSTATUS:
  99                 /* XXX: something is clearing TSR */
 100                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 101                 /* returns 1 if last reset was caused by the WDT */
 102                 return (tmp ? 1 : 0);
 103         case WDIOC_KEEPALIVE:
 104                 booke_wdt_ping();
 105                 return 0;
 106         case WDIOC_SETTIMEOUT:
 107                 if (get_user(booke_wdt_period, p))
 108                         return -EFAULT;
 109                 mtspr(SPRN_TCR, (mfspr(SPRN_TCR)&~WDTP(0))|WDTP(booke_wdt_period));
 110                 return 0;
 111         case WDIOC_GETTIMEOUT:
 112                 return put_user(booke_wdt_period, p);
 113         case WDIOC_SETOPTIONS:
 114                 if (get_user(tmp, p))
 115                         return -EINVAL;
 116                 if (tmp == WDIOS_ENABLECARD) {
 117                         booke_wdt_ping();
 118                         break;
 119                 } else
 120                         return -EINVAL;
 121                 return 0;
 122         default:
 123                 return -ENOTTY;
 124         }
 125
 126         return 0;
 127 }
 128
 129 static int booke_wdt_open(struct inode *inode, struct file *file)
 130 {
 131         spin_lock(&booke_wdt_lock);
 132         if (booke_wdt_enabled == 0) {
 133                 booke_wdt_enabled = 1;
 134                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 135                 printk(KERN_INFO "PowerPC Book-E Watchdog Timer Enabled "
 136                                 "(wdt_period=%d)\n", booke_wdt_period);
 137         }
 138         spin_unlock(&booke_wdt_lock);
 139
 140         return nonseekable_open(inode, file);
 141 }
 142
 143 static const struct file_operations booke_wdt_fops = {
 144         .owner = THIS_MODULE,
 145         .llseek = no_llseek,
 146         .write = booke_wdt_write,
 147         .ioctl = booke_wdt_ioctl,
 148         .open = booke_wdt_open,
 149 };
 150
 151 static struct miscdevice booke_wdt_miscdev = {
 152         .minor = WATCHDOG_MINOR,
 153         .name = "watchdog",
 154         .fops = &booke_wdt_fops,
 155 };
 156
 157 static void __exit booke_wdt_exit(void)
 158 {
 159         misc_deregister(&booke_wdt_miscdev);
 160 }
 161
 162 static int __init booke_wdt_init(void)
 163 {
 164         int ret = 0;
 165
 166         printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 167         ident.firmware_version = cur_cpu_spec->pvr_value;
 168
 169         ret = misc_register(&booke_wdt_miscdev);
 170         if (ret) {
 171                 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n",
 172                                 WATCHDOG_MINOR, ret);
 173                 return ret;
 174         }
 175
 176         spin_lock(&booke_wdt_lock);
 177         if (booke_wdt_enabled == 1) {
 178                 printk(KERN_INFO "PowerPC Book-E Watchdog Timer Enabled "
 179                                 "(wdt_period=%d)\n", booke_wdt_period);
 180                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 181         }
 182         spin_unlock(&booke_wdt_lock);
 183
 184         return ret;
 185 }
 186 device_initcall(booke_wdt_init);