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, 2010 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 u32 booke_wdt_enabled;
  37 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
  38
  39 #ifdef  CONFIG_FSL_BOOKE
  40 #define WDTP(x)         ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
  41 #define WDTP_MASK       (WDTP(0x3f))
  42 #else
  43 #define WDTP(x)         (TCR_WP(x))
  44 #define WDTP_MASK       (TCR_WP_MASK)
  45 #endif
  46
  47 static DEFINE_SPINLOCK(booke_wdt_lock);
  48
  49 /* For the specified period, determine the number of seconds
  50  * corresponding to the reset time.  There will be a watchdog
  51  * exception at approximately 3/5 of this time.
  52  *
  53  * The formula to calculate this is given by:
  54  * 2.5 * (2^(63-period+1)) / timebase_freq
  55  *
  56  * In order to simplify things, we assume that period is
  57  * at least 1.  This will still result in a very long timeout.
  58  */
  59 static unsigned long long period_to_sec(unsigned int period)
  60 {
  61         unsigned long long tmp = 1ULL << (64 - period);
  62         unsigned long tmp2 = ppc_tb_freq;
  63
  64         /* tmp may be a very large number and we don't want to overflow,
  65          * so divide the timebase freq instead of multiplying tmp
  66          */
  67         tmp2 = tmp2 / 5 * 2;
  68
  69         do_div(tmp, tmp2);
  70         return tmp;
  71 }
  72
  73 /*
  74  * This procedure will find the highest period which will give a timeout
  75  * greater than the one required. e.g. for a bus speed of 66666666 and
  76  * and a parameter of 2 secs, then this procedure will return a value of 38.
  77  */
  78 static unsigned int sec_to_period(unsigned int secs)
  79 {
  80         unsigned int period;
  81         for (period = 63; period > 0; period--) {
  82                 if (period_to_sec(period) >= secs)
  83                         return period;
  84         }
  85         return 0;
  86 }
  87
  88 static void __booke_wdt_ping(void *data)
  89 {
  90         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
  91 }
  92
  93 static void booke_wdt_ping(void)
  94 {
  95         on_each_cpu(__booke_wdt_ping, NULL, 0);
  96 }
  97
  98 static void __booke_wdt_enable(void *data)
  99 {
 100         u32 val;
 101
 102         /* clear status before enabling watchdog */
 103         __booke_wdt_ping(NULL);
 104         val = mfspr(SPRN_TCR);
 105         val &= ~WDTP_MASK;
 106         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
 107
 108         mtspr(SPRN_TCR, val);
 109 }
 110
 111 /**
 112  * booke_wdt_disable - disable the watchdog on the given CPU
 113  *
 114  * This function is called on each CPU.  It disables the watchdog on that CPU.
 115  *
 116  * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
 117  * effectively disable the watchdog by setting its period to the maximum value.
 118  */
 119 static void __booke_wdt_disable(void *data)
 120 {
 121         u32 val;
 122
 123         val = mfspr(SPRN_TCR);
 124         val &= ~(TCR_WIE | WDTP_MASK);
 125         mtspr(SPRN_TCR, val);
 126
 127         /* clear status to make sure nothing is pending */
 128         __booke_wdt_ping(NULL);
 129
 130 }
 131
 132 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
 133                                 size_t count, loff_t *ppos)
 134 {
 135         booke_wdt_ping();
 136         return count;
 137 }
 138
 139 static struct watchdog_info ident = {
 140         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 141         .identity = "PowerPC Book-E Watchdog",
 142 };
 143
 144 static long booke_wdt_ioctl(struct file *file,
 145                                 unsigned int cmd, unsigned long arg)
 146 {
 147         u32 tmp = 0;
 148         u32 __user *p = (u32 __user *)arg;
 149
 150         switch (cmd) {
 151         case WDIOC_GETSUPPORT:
 152                 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
 153                         return -EFAULT;
 154         case WDIOC_GETSTATUS:
 155                 return put_user(0, p);
 156         case WDIOC_GETBOOTSTATUS:
 157                 /* XXX: something is clearing TSR */
 158                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 159                 /* returns CARDRESET if last reset was caused by the WDT */
 160                 return (tmp ? WDIOF_CARDRESET : 0);
 161         case WDIOC_SETOPTIONS:
 162                 if (get_user(tmp, p))
 163                         return -EINVAL;
 164                 if (tmp == WDIOS_ENABLECARD) {
 165                         booke_wdt_ping();
 166                         break;
 167                 } else
 168                         return -EINVAL;
 169                 return 0;
 170         case WDIOC_KEEPALIVE:
 171                 booke_wdt_ping();
 172                 return 0;
 173         case WDIOC_SETTIMEOUT:
 174                 if (get_user(tmp, p))
 175                         return -EFAULT;
 176 #ifdef  CONFIG_FSL_BOOKE
 177                 /* period of 1 gives the largest possible timeout */
 178                 if (tmp > period_to_sec(1))
 179                         return -EINVAL;
 180                 booke_wdt_period = sec_to_period(tmp);
 181 #else
 182                 booke_wdt_period = tmp;
 183 #endif
 184                 mtspr(SPRN_TCR, (mfspr(SPRN_TCR) & ~WDTP_MASK) |
 185                                                 WDTP(booke_wdt_period));
 186                 return 0;
 187         case WDIOC_GETTIMEOUT:
 188                 return put_user(booke_wdt_period, p);
 189         default:
 190                 return -ENOTTY;
 191         }
 192
 193         return 0;
 194 }
 195
 196 static int booke_wdt_open(struct inode *inode, struct file *file)
 197 {
 198         spin_lock(&booke_wdt_lock);
 199         if (booke_wdt_enabled == 0) {
 200                 booke_wdt_enabled = 1;
 201                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 202                 printk(KERN_INFO
 203                       "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 204                                 booke_wdt_period);
 205         }
 206         spin_unlock(&booke_wdt_lock);
 207
 208         return nonseekable_open(inode, file);
 209 }
 210
 211 static int booke_wdt_release(struct inode *inode, struct file *file)
 212 {
 213         on_each_cpu(__booke_wdt_disable, NULL, 0);
 214         booke_wdt_enabled = 0;
 215
 216         return 0;
 217 }
 218
 219 static const struct file_operations booke_wdt_fops = {
 220         .owner = THIS_MODULE,
 221         .llseek = no_llseek,
 222         .write = booke_wdt_write,
 223         .unlocked_ioctl = booke_wdt_ioctl,
 224         .open = booke_wdt_open,
 225         .release = booke_wdt_release,
 226 };
 227
 228 static struct miscdevice booke_wdt_miscdev = {
 229         .minor = WATCHDOG_MINOR,
 230         .name = "watchdog",
 231         .fops = &booke_wdt_fops,
 232 };
 233
 234 static void __exit booke_wdt_exit(void)
 235 {
 236         misc_deregister(&booke_wdt_miscdev);
 237 }
 238
 239 static int __init booke_wdt_init(void)
 240 {
 241         int ret = 0;
 242
 243         printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n");
 244         ident.firmware_version = cur_cpu_spec->pvr_value;
 245
 246         ret = misc_register(&booke_wdt_miscdev);
 247         if (ret) {
 248                 printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n",
 249                                 WATCHDOG_MINOR, ret);
 250                 return ret;
 251         }
 252
 253         spin_lock(&booke_wdt_lock);
 254         if (booke_wdt_enabled == 1) {
 255                 printk(KERN_INFO
 256                       "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 257                                 booke_wdt_period);
 258                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 259         }
 260         spin_unlock(&booke_wdt_lock);
 261
 262         return ret;
 263 }
 264
 265 module_init(booke_wdt_init);
 266 module_exit(booke_wdt_exit);
 267
 268 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
 269 MODULE_LICENSE("GPL");