drivers/char/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_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
  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_enable:
  52  */
  53 static __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  */
  66 static __inline__ void booke_wdt_ping(void)
  67 {
  68         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  69 }
  70
  71 /*
  72  * booke_wdt_write:
  73  */
  74 static 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
  81 static 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  */
  90 static 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 -ENOIOCTLCMD;
 129         }
 130
 131         return 0;
 132 }
 133 /*
 134  * booke_wdt_open:
 135  */
 136 static 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
 148 static 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
 156 static struct miscdevice booke_wdt_miscdev = {
 157   .minor = WATCHDOG_MINOR,
 158   .name = "watchdog",
 159   .fops = &booke_wdt_fops,
 160 };
 161
 162 static void __exit booke_wdt_exit(void)
 163 {
 164         misc_deregister(&booke_wdt_miscdev);
 165 }
 166
 167 /*
 168  * booke_wdt_init:
 169  */
 170 static 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 }
 192 device_initcall(booke_wdt_init);