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/config.h>
  18 #include <linux/module.h>
  19 #include <linux/fs.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/notifier.h>
  22 #include <linux/watchdog.h>
  23
  24 #include <asm/reg_booke.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/system.h>
  27
  28 /* If the kernel parameter wdt_enable=1, the watchdog will be enabled at boot.
  29  * Also, the wdt_period sets the watchdog timer period timeout.
  30  * For E500 cpus the wdt_period sets which bit changing from 0->1 will
  31  * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
  32  * first time nothing will happen, the second time a watchdog exception will
  33  * occur, and the final time the board will reset.
  34  */
  35
  36 #ifdef  CONFIG_FSL_BOOKE
  37 #define WDT_PERIOD_DEFAULT 63   /* Ex. wdt_period=28 bus=333Mhz , reset=~40sec */
  38 #else
  39 #define WDT_PERIOD_DEFAULT 4    /* Refer to the PPC40x and PPC4xx manuals */
  40 #endif                          /* for timing information */
  41
  42 u32 booke_wdt_enabled = 0;
  43 u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
  44
  45 #ifdef  CONFIG_FSL_BOOKE
  46 #define WDTP(x)         ((((63-x)&0x3)<<30)|(((63-x)&0x3c)<<15))
  47 #else
  48 #define WDTP(x)         (TCR_WP(x))
  49 #endif
  50
  51 /*
  52  * booke_wdt_enable:
  53  */
  54 static __inline__ void booke_wdt_enable(void)
  55 {
  56         u32 val;
  57
  58         val = mfspr(SPRN_TCR);
  59         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
  60
  61         mtspr(SPRN_TCR, val);
  62 }
  63
  64 /*
  65  * booke_wdt_ping:
  66  */
  67 static __inline__ void booke_wdt_ping(void)
  68 {
  69         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  70 }
  71
  72 /*
  73  * booke_wdt_write:
  74  */
  75 static ssize_t booke_wdt_write (struct file *file, const char __user *buf,
  76                                 size_t count, loff_t *ppos)
  77 {
  78         booke_wdt_ping();
  79         return count;
  80 }
  81
  82 static struct watchdog_info ident = {
  83   .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  84   .firmware_version = 0,
  85   .identity = "PowerPC Book-E Watchdog",
  86 };
  87
  88 /*
  89  * booke_wdt_ioctl:
  90  */
  91 static int booke_wdt_ioctl (struct inode *inode, struct file *file,
  92                             unsigned int cmd, unsigned long arg)
  93 {
  94         u32 tmp = 0;
  95         u32 __user *p = (u32 __user *)arg;
  96
  97         switch (cmd) {
  98         case WDIOC_GETSUPPORT:
  99                 if (copy_to_user ((struct watchdog_info __user *) arg, &ident,
 100                                 sizeof(struct watchdog_info)))
 101                         return -EFAULT;
 102         case WDIOC_GETSTATUS:
 103                 return put_user(ident.options, p);
 104         case WDIOC_GETBOOTSTATUS:
 105                 /* XXX: something is clearing TSR */
 106                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 107                 /* returns 1 if last reset was caused by the WDT */
 108                 return (tmp ? 1 : 0);
 109         case WDIOC_KEEPALIVE:
 110                 booke_wdt_ping();
 111                 return 0;
 112         case WDIOC_SETTIMEOUT:
 113                 if (get_user(booke_wdt_period, p))
 114                         return -EFAULT;
 115                 mtspr(SPRN_TCR, (mfspr(SPRN_TCR)&~WDTP(0))|WDTP(booke_wdt_period));
 116                 return 0;
 117         case WDIOC_GETTIMEOUT:
 118                 return put_user(booke_wdt_period, p);
 119         case WDIOC_SETOPTIONS:
 120                 if (get_user(tmp, p))
 121                         return -EINVAL;
 122                 if (tmp == WDIOS_ENABLECARD) {
 123                         booke_wdt_ping();
 124                         break;
 125                 } else
 126                         return -EINVAL;
 127                 return 0;
 128         default:
 129                 return -ENOIOCTLCMD;
 130         }
 131
 132         return 0;
 133 }
 134 /*
 135  * booke_wdt_open:
 136  */
 137 static int booke_wdt_open (struct inode *inode, struct file *file)
 138 {
 139         if (booke_wdt_enabled == 0) {
 140                 booke_wdt_enabled = 1;
 141                 booke_wdt_enable();
 142                 printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 143                                 booke_wdt_period);
 144         }
 145
 146         return 0;
 147 }
 148
 149 static struct file_operations booke_wdt_fops = {
 150   .owner = THIS_MODULE,
 151   .llseek = no_llseek,
 152   .write = booke_wdt_write,
 153   .ioctl = booke_wdt_ioctl,
 154   .open = booke_wdt_open,
 155 };
 156
 157 static struct miscdevice booke_wdt_miscdev = {
 158   .minor = WATCHDOG_MINOR,
 159   .name = "watchdog",
 160   .fops = &booke_wdt_fops,
 161 };
 162
 163 static void __exit booke_wdt_exit(void)
 164 {
 165         misc_deregister(&booke_wdt_miscdev);
 166 }
 167
 168 /*
 169  * booke_wdt_init:
 170  */
 171 static int __init booke_wdt_init(void)
 172 {
 173         int ret = 0;
 174
 175         printk (KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 176         ident.firmware_version = cur_cpu_spec->pvr_value;
 177
 178         ret = misc_register(&booke_wdt_miscdev);
 179         if (ret) {
 180                 printk (KERN_CRIT "Cannot register miscdev on minor=%d (err=%d)\n",
 181                                 WATCHDOG_MINOR, ret);
 182                 return ret;
 183         }
 184
 185         if (booke_wdt_enabled == 1) {
 186                 printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 187                                 booke_wdt_period);
 188                 booke_wdt_enable();
 189         }
 190
 191         return ret;
 192 }
 193 device_initcall(booke_wdt_init);