LXR linux/drivers/watchdog/booke

   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
  40u32 booke_wdt_enabled;
  41u32 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
  49static DEFINE_SPINLOCK(booke_wdt_lock);
  50
  51static void __booke_wdt_ping(void *data)
  52{
  53        mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  54}
  55
  56static void booke_wdt_ping(void)
  57{
  58        on_each_cpu(__booke_wdt_ping, NULL, 0);
  59}
  60
  61static 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
  73static 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
  80static struct watchdog_info ident = {
  81        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  82        .identity = "PowerPC Book-E Watchdog",
  83};
  84
  85static long booke_wdt_ioctl(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(arg, &ident, sizeof(struct watchdog_info)))
  94                        return -EFAULT;
  95        case WDIOC_GETSTATUS:
  96                return put_user(ident.options, p);
  97        case WDIOC_GETBOOTSTATUS:
  98                /* XXX: something is clearing TSR */
  99                tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 100                /* returns 1 if last reset was caused by the WDT */
 101                return (tmp ? 1 : 0);
 102        case WDIOC_SETOPTIONS:
 103                if (get_user(tmp, p))
 104                        return -EINVAL;
 105                if (tmp == WDIOS_ENABLECARD) {
 106                        booke_wdt_ping();
 107                        break;
 108                } else
 109                        return -EINVAL;
 110                return 0;
 111        case WDIOC_KEEPALIVE:
 112                booke_wdt_ping();
 113                return 0;
 114        case WDIOC_SETTIMEOUT:
 115                if (get_user(booke_wdt_period, p))
 116                        return -EFAULT;
 117                mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP(0)) |
 118                                                WDTP(booke_wdt_period));
 119                return 0;
 120        case WDIOC_GETTIMEOUT:
 121                return put_user(booke_wdt_period, p);
 122        default:
 123                return -ENOTTY;
 124        }
 125
 126        return 0;
 127}
 128
 129static 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
 136                      "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 137                                booke_wdt_period);
 138        }
 139        spin_unlock(&booke_wdt_lock);
 140
 141        return nonseekable_open(inode, file);
 142}
 143
 144static const struct file_operations booke_wdt_fops = {
 145        .owner = THIS_MODULE,
 146        .llseek = no_llseek,
 147        .write = booke_wdt_write,
 148        .unlocked_ioctl = booke_wdt_ioctl,
 149        .open = booke_wdt_open,
 150};
 151
 152static struct miscdevice booke_wdt_miscdev = {
 153        .minor = WATCHDOG_MINOR,
 154        .name = "watchdog",
 155        .fops = &booke_wdt_fops,
 156};
 157
 158static void __exit booke_wdt_exit(void)
 159{
 160        misc_deregister(&booke_wdt_miscdev);
 161}
 162
 163static int __init booke_wdt_init(void)
 164{
 165        int ret = 0;
 166
 167        printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 168        ident.firmware_version = cur_cpu_spec->pvr_value;
 169
 170        ret = misc_register(&booke_wdt_miscdev);
 171        if (ret) {
 172                printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n",
 173                                WATCHDOG_MINOR, ret);
 174                return ret;
 175        }
 176
 177        spin_lock(&booke_wdt_lock);
 178        if (booke_wdt_enabled == 1) {
 179                printk(KERN_INFO
 180                      "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 181                                booke_wdt_period);
 182                on_each_cpu(__booke_wdt_enable, NULL, 0);
 183        }
 184        spin_unlock(&booke_wdt_lock);
 185
 186        return ret;
 187}
 188device_initcall(booke_wdt_init);
 189