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 #include <linux/uaccess.h>
  22
  23 #include <asm/reg_booke.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 #define WDTP_MASK       (WDTP(0))
  46 #else
  47 #define WDTP(x)         (TCR_WP(x))
  48 #define WDTP_MASK       (TCR_WP_MASK)
  49 #endif
  50
  51 static DEFINE_SPINLOCK(booke_wdt_lock);
  52
  53 static void __booke_wdt_ping(void *data)
  54 {
  55         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  56 }
  57
  58 static void booke_wdt_ping(void)
  59 {
  60         on_each_cpu(__booke_wdt_ping, NULL, 0);
  61 }
  62
  63 static void __booke_wdt_enable(void *data)
  64 {
  65         u32 val;
  66
  67         /* clear status before enabling watchdog */
  68         __booke_wdt_ping(NULL);
  69         val = mfspr(SPRN_TCR);
  70         val &= ~WDTP_MASK;
  71         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
  72
  73         mtspr(SPRN_TCR, val);
  74 }
  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         .identity = "PowerPC Book-E Watchdog",
  86 };
  87
  88 static long booke_wdt_ioctl(struct file *file,
  89                                 unsigned int cmd, unsigned long arg)
  90 {
  91         u32 tmp = 0;
  92         u32 __user *p = (u32 __user *)arg;
  93
  94         switch (cmd) {
  95         case WDIOC_GETSUPPORT:
  96                 if (copy_to_user(arg, &ident, sizeof(struct watchdog_info)))
  97                         return -EFAULT;
  98         case WDIOC_GETSTATUS:
  99                 return put_user(ident.options, p);
 100         case WDIOC_GETBOOTSTATUS:
 101                 /* XXX: something is clearing TSR */
 102                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 103                 /* returns 1 if last reset was caused by the WDT */
 104                 return (tmp ? 1 : 0);
 105         case WDIOC_SETOPTIONS:
 106                 if (get_user(tmp, p))
 107                         return -EINVAL;
 108                 if (tmp == WDIOS_ENABLECARD) {
 109                         booke_wdt_ping();
 110                         break;
 111                 } else
 112                         return -EINVAL;
 113                 return 0;
 114         case WDIOC_KEEPALIVE:
 115                 booke_wdt_ping();
 116                 return 0;
 117         case WDIOC_SETTIMEOUT:
 118                 if (get_user(booke_wdt_period, p))
 119                         return -EFAULT;
 120                 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP_MASK) |
 121                                                 WDTP(booke_wdt_period));
 122                 return 0;
 123         case WDIOC_GETTIMEOUT:
 124                 return put_user(booke_wdt_period, p);
 125         default:
 126                 return -ENOTTY;
 127         }
 128
 129         return 0;
 130 }
 131
 132 static int booke_wdt_open(struct inode *inode, struct file *file)
 133 {
 134         spin_lock(&booke_wdt_lock);
 135         if (booke_wdt_enabled == 0) {
 136                 booke_wdt_enabled = 1;
 137                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 138                 printk(KERN_INFO
 139                       "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 140                                 booke_wdt_period);
 141         }
 142         spin_unlock(&booke_wdt_lock);
 143
 144         return nonseekable_open(inode, file);
 145 }
 146
 147 static const struct file_operations booke_wdt_fops = {
 148         .owner = THIS_MODULE,
 149         .llseek = no_llseek,
 150         .write = booke_wdt_write,
 151         .unlocked_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 static int __init booke_wdt_init(void)
 167 {
 168         int ret = 0;
 169
 170         printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 171         ident.firmware_version = cur_cpu_spec->pvr_value;
 172
 173         ret = misc_register(&booke_wdt_miscdev);
 174         if (ret) {
 175                 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n",
 176                                 WATCHDOG_MINOR, ret);
 177                 return ret;
 178         }
 179
 180         spin_lock(&booke_wdt_lock);
 181         if (booke_wdt_enabled == 1) {
 182                 printk(KERN_INFO
 183                       "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 184                                 booke_wdt_period);
 185                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 186         }
 187         spin_unlock(&booke_wdt_lock);
 188
 189         return ret;
 190 }
 191 device_initcall(booke_wdt_init);