LXR linux/drivers/char/watchdog/booke

   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_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
  41u32 booke_wdt_enabled = 0;
  42u32 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_enable:
  52 */
  53static __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(booke_wdt_period));
  59
  60        mtspr(SPRN_TCR, val);
  61}
  62
  63/*
  64 * booke_wdt_ping:
  65 */
  66static __inline__ void booke_wdt_ping(void)
  67{
  68        mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  69}
  70
  71/*
  72 * booke_wdt_write:
  73 */
  74static ssize_t booke_wdt_write (struct file *file, const char __user *buf,
  75                                size_t count, loff_t *ppos)
  76{
  77        booke_wdt_ping();
  78        return count;
  79}
  80
  81static 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 */
  90static int booke_wdt_ioctl (struct inode *inode, struct file *file,
  91                            unsigned int cmd, unsigned long arg)
  92{
  93        u32 tmp = 0;
  94        u32 __user *p = (u32 __user *)arg;
  95
  96        switch (cmd) {
  97        case WDIOC_GETSUPPORT:
  98                if (copy_to_user ((struct watchdog_info __user *) arg, &ident,
  99                                sizeof(struct watchdog_info)))
 100                        return -EFAULT;
 101        case WDIOC_GETSTATUS:
 102                return put_user(ident.options, p);
 103        case WDIOC_GETBOOTSTATUS:
 104                /* XXX: something is clearing TSR */
 105                tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 106                /* returns 1 if last reset was caused by the WDT */
 107                return (tmp ? 1 : 0);
 108        case WDIOC_KEEPALIVE:
 109                booke_wdt_ping();
 110                return 0;
 111        case WDIOC_SETTIMEOUT:
 112                if (get_user(booke_wdt_period, p))
 113                        return -EFAULT;
 114                mtspr(SPRN_TCR, (mfspr(SPRN_TCR)&~WDTP(0))|WDTP(booke_wdt_period));
 115                return 0;
 116        case WDIOC_GETTIMEOUT:
 117                return put_user(booke_wdt_period, p);
 118        case WDIOC_SETOPTIONS:
 119                if (get_user(tmp, p))
 120                        return -EINVAL;
 121                if (tmp == WDIOS_ENABLECARD) {
 122                        booke_wdt_ping();
 123                        break;
 124                } else
 125                        return -EINVAL;
 126                return 0;
 127        default:
 128                return -ENOTTY;
 129        }
 130
 131        return 0;
 132}
 133/*
 134 * booke_wdt_open:
 135 */
 136static int booke_wdt_open (struct inode *inode, struct file *file)
 137{
 138        if (booke_wdt_enabled == 0) {
 139                booke_wdt_enabled = 1;
 140                booke_wdt_enable();
 141                printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 142                                booke_wdt_period);
 143        }
 144
 145        return 0;
 146}
 147
 148static const struct file_operations booke_wdt_fops = {
 149  .owner = THIS_MODULE,
 150  .llseek = no_llseek,
 151  .write = booke_wdt_write,
 152  .ioctl = booke_wdt_ioctl,
 153  .open = booke_wdt_open,
 154};
 155
 156static struct miscdevice booke_wdt_miscdev = {
 157  .minor = WATCHDOG_MINOR,
 158  .name = "watchdog",
 159  .fops = &booke_wdt_fops,
 160};
 161
 162static void __exit booke_wdt_exit(void)
 163{
 164        misc_deregister(&booke_wdt_miscdev);
 165}
 166
 167/*
 168 * booke_wdt_init:
 169 */
 170static int __init booke_wdt_init(void)
 171{
 172        int ret = 0;
 173
 174        printk (KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 175        ident.firmware_version = cur_cpu_spec->pvr_value;
 176
 177        ret = misc_register(&booke_wdt_miscdev);
 178        if (ret) {
 179                printk (KERN_CRIT "Cannot register miscdev on minor=%d (err=%d)\n",
 180                                WATCHDOG_MINOR, ret);
 181                return ret;
 182        }
 183
 184        if (booke_wdt_enabled == 1) {
 185                printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 186                                booke_wdt_period);
 187                booke_wdt_enable();
 188        }
 189
 190        return ret;
 191}
 192device_initcall(booke_wdt_init);
 193