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 #include <asm/time.h>
  26 #include <asm/div64.h>
  27
  28 /* If the kernel parameter wdt=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 38   /* Ex. wdt_period=28 bus=333Mhz,reset=~40sec */
  38 #else
  39 #define WDT_PERIOD_DEFAULT 3    /* Refer to the PPC40x and PPC4xx manuals */
  40 #endif                          /* for timing information */
  41
  42 u32 booke_wdt_enabled;
  43 u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
  44
  45 #ifdef  CONFIG_FSL_BOOKE
  46 #define WDTP(x)         ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
  47 #define WDTP_MASK       (WDTP(0x3f))
  48 #else
  49 #define WDTP(x)         (TCR_WP(x))
  50 #define WDTP_MASK       (TCR_WP_MASK)
  51 #endif
  52
  53 static DEFINE_SPINLOCK(booke_wdt_lock);
  54
  55 /* For the specified period, determine the number of seconds
  56  * corresponding to the reset time.  There will be a watchdog
  57  * exception at approximately 3/5 of this time.
  58  *
  59  * The formula to calculate this is given by:
  60  * 2.5 * (2^(63-period+1)) / timebase_freq
  61  *
  62  * In order to simplify things, we assume that period is
  63  * at least 1.  This will still result in a very long timeout.
  64  */
  65 static unsigned long long period_to_sec(unsigned int period)
  66 {
  67         unsigned long long tmp = 1ULL << (64 - period);
  68         unsigned long tmp2 = ppc_tb_freq;
  69
  70         /* tmp may be a very large number and we don't want to overflow,
  71          * so divide the timebase freq instead of multiplying tmp
  72          */
  73         tmp2 = tmp2 / 5 * 2;
  74
  75         do_div(tmp, tmp2);
  76         return tmp;
  77 }
  78
  79 /*
  80  * This procedure will find the highest period which will give a timeout
  81  * greater than the one required. e.g. for a bus speed of 66666666 and
  82  * and a parameter of 2 secs, then this procedure will return a value of 38.
  83  */
  84 static unsigned int sec_to_period(unsigned int secs)
  85 {
  86         unsigned int period;
  87         for (period = 63; period > 0; period--) {
  88                 if (period_to_sec(period) >= secs)
  89                         return period;
  90         }
  91         return 0;
  92 }
  93
  94 static void __booke_wdt_ping(void *data)
  95 {
  96         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  97 }
  98
  99 static void booke_wdt_ping(void)
 100 {
 101         on_each_cpu(__booke_wdt_ping, NULL, 0);
 102 }
 103
 104 static void __booke_wdt_enable(void *data)
 105 {
 106         u32 val;
 107
 108         /* clear status before enabling watchdog */
 109         __booke_wdt_ping(NULL);
 110         val = mfspr(SPRN_TCR);
 111         val &= ~WDTP_MASK;
 112         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
 113
 114         mtspr(SPRN_TCR, val);
 115 }
 116
 117 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
 118                                 size_t count, loff_t *ppos)
 119 {
 120         booke_wdt_ping();
 121         return count;
 122 }
 123
 124 static struct watchdog_info ident = {
 125         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 126         .identity = "PowerPC Book-E Watchdog",
 127 };
 128
 129 static long booke_wdt_ioctl(struct file *file,
 130                                 unsigned int cmd, unsigned long arg)
 131 {
 132         u32 tmp = 0;
 133         u32 __user *p = (u32 __user *)arg;
 134
 135         switch (cmd) {
 136         case WDIOC_GETSUPPORT:
 137                 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
 138                         return -EFAULT;
 139         case WDIOC_GETSTATUS:
 140                 return put_user(0, p);
 141         case WDIOC_GETBOOTSTATUS:
 142                 /* XXX: something is clearing TSR */
 143                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 144                 /* returns CARDRESET if last reset was caused by the WDT */
 145                 return (tmp ? WDIOF_CARDRESET : 0);
 146         case WDIOC_SETOPTIONS:
 147                 if (get_user(tmp, p))
 148                         return -EINVAL;
 149                 if (tmp == WDIOS_ENABLECARD) {
 150                         booke_wdt_ping();
 151                         break;
 152                 } else
 153                         return -EINVAL;
 154                 return 0;
 155         case WDIOC_KEEPALIVE:
 156                 booke_wdt_ping();
 157                 return 0;
 158         case WDIOC_SETTIMEOUT:
 159                 if (get_user(tmp, p))
 160                         return -EFAULT;
 161 #ifdef  CONFIG_FSL_BOOKE
 162                 /* period of 1 gives the largest possible timeout */
 163                 if (tmp > period_to_sec(1))
 164                         return -EINVAL;
 165                 booke_wdt_period = sec_to_period(tmp);
 166 #else
 167                 booke_wdt_period = tmp;
 168 #endif
 169                 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP_MASK) |
 170                                                 WDTP(booke_wdt_period));
 171                 return 0;
 172         case WDIOC_GETTIMEOUT:
 173                 return put_user(booke_wdt_period, p);
 174         default:
 175                 return -ENOTTY;
 176         }
 177
 178         return 0;
 179 }
 180
 181 static int booke_wdt_open(struct inode *inode, struct file *file)
 182 {
 183         spin_lock(&booke_wdt_lock);
 184         if (booke_wdt_enabled == 0) {
 185                 booke_wdt_enabled = 1;
 186                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 187                 printk(KERN_INFO
 188                       "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 189                                 booke_wdt_period);
 190         }
 191         spin_unlock(&booke_wdt_lock);
 192
 193         return nonseekable_open(inode, file);
 194 }
 195
 196 static const struct file_operations booke_wdt_fops = {
 197         .owner = THIS_MODULE,
 198         .llseek = no_llseek,
 199         .write = booke_wdt_write,
 200         .unlocked_ioctl = booke_wdt_ioctl,
 201         .open = booke_wdt_open,
 202 };
 203
 204 static struct miscdevice booke_wdt_miscdev = {
 205         .minor = WATCHDOG_MINOR,
 206         .name = "watchdog",
 207         .fops = &booke_wdt_fops,
 208 };
 209
 210 static void __exit booke_wdt_exit(void)
 211 {
 212         misc_deregister(&booke_wdt_miscdev);
 213 }
 214
 215 static int __init booke_wdt_init(void)
 216 {
 217         int ret = 0;
 218
 219         printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 220         ident.firmware_version = cur_cpu_spec->pvr_value;
 221
 222         ret = misc_register(&booke_wdt_miscdev);
 223         if (ret) {
 224                 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n",
 225                                 WATCHDOG_MINOR, ret);
 226                 return ret;
 227         }
 228
 229         spin_lock(&booke_wdt_lock);
 230         if (booke_wdt_enabled == 1) {
 231                 printk(KERN_INFO
 232                       "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 233                                 booke_wdt_period);
 234                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 235         }
 236         spin_unlock(&booke_wdt_lock);
 237
 238         return ret;
 239 }
 240 device_initcall(booke_wdt_init);