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, 2010-2011 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/time.h>
  25 #include <asm/div64.h>
  26
  27 /* If the kernel parameter wdt=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 u32 booke_wdt_enabled;
  36 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
  37
  38 #ifdef  CONFIG_FSL_BOOKE
  39 #define WDTP(x)         ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
  40 #define WDTP_MASK       (WDTP(0x3f))
  41 #else
  42 #define WDTP(x)         (TCR_WP(x))
  43 #define WDTP_MASK       (TCR_WP_MASK)
  44 #endif
  45
  46 static DEFINE_SPINLOCK(booke_wdt_lock);
  47
  48 /* For the specified period, determine the number of seconds
  49  * corresponding to the reset time.  There will be a watchdog
  50  * exception at approximately 3/5 of this time.
  51  *
  52  * The formula to calculate this is given by:
  53  * 2.5 * (2^(63-period+1)) / timebase_freq
  54  *
  55  * In order to simplify things, we assume that period is
  56  * at least 1.  This will still result in a very long timeout.
  57  */
  58 static unsigned long long period_to_sec(unsigned int period)
  59 {
  60         unsigned long long tmp = 1ULL << (64 - period);
  61         unsigned long tmp2 = ppc_tb_freq;
  62
  63         /* tmp may be a very large number and we don't want to overflow,
  64          * so divide the timebase freq instead of multiplying tmp
  65          */
  66         tmp2 = tmp2 / 5 * 2;
  67
  68         do_div(tmp, tmp2);
  69         return tmp;
  70 }
  71
  72 /*
  73  * This procedure will find the highest period which will give a timeout
  74  * greater than the one required. e.g. for a bus speed of 66666666 and
  75  * and a parameter of 2 secs, then this procedure will return a value of 38.
  76  */
  77 static unsigned int sec_to_period(unsigned int secs)
  78 {
  79         unsigned int period;
  80         for (period = 63; period > 0; period--) {
  81                 if (period_to_sec(period) >= secs)
  82                         return period;
  83         }
  84         return 0;
  85 }
  86
  87 static void __booke_wdt_set(void *data)
  88 {
  89         u32 val;
  90
  91         val = mfspr(SPRN_TCR);
  92         val &= ~WDTP_MASK;
  93         val |= WDTP(booke_wdt_period);
  94
  95         mtspr(SPRN_TCR, val);
  96 }
  97
  98 static void booke_wdt_set(void)
  99 {
 100         on_each_cpu(__booke_wdt_set, NULL, 0);
 101 }
 102
 103 static void __booke_wdt_ping(void *data)
 104 {
 105         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
 106 }
 107
 108 static void booke_wdt_ping(void)
 109 {
 110         on_each_cpu(__booke_wdt_ping, NULL, 0);
 111 }
 112
 113 static void __booke_wdt_enable(void *data)
 114 {
 115         u32 val;
 116
 117         /* clear status before enabling watchdog */
 118         __booke_wdt_ping(NULL);
 119         val = mfspr(SPRN_TCR);
 120         val &= ~WDTP_MASK;
 121         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
 122
 123         mtspr(SPRN_TCR, val);
 124 }
 125
 126 /**
 127  * booke_wdt_disable - disable the watchdog on the given CPU
 128  *
 129  * This function is called on each CPU.  It disables the watchdog on that CPU.
 130  *
 131  * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
 132  * effectively disable the watchdog by setting its period to the maximum value.
 133  */
 134 static void __booke_wdt_disable(void *data)
 135 {
 136         u32 val;
 137
 138         val = mfspr(SPRN_TCR);
 139         val &= ~(TCR_WIE | WDTP_MASK);
 140         mtspr(SPRN_TCR, val);
 141
 142         /* clear status to make sure nothing is pending */
 143         __booke_wdt_ping(NULL);
 144
 145 }
 146
 147 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
 148                                 size_t count, loff_t *ppos)
 149 {
 150         booke_wdt_ping();
 151         return count;
 152 }
 153
 154 static struct watchdog_info ident = {
 155         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 156         .identity = "PowerPC Book-E Watchdog",
 157 };
 158
 159 static long booke_wdt_ioctl(struct file *file,
 160                                 unsigned int cmd, unsigned long arg)
 161 {
 162         u32 tmp = 0;
 163         u32 __user *p = (u32 __user *)arg;
 164
 165         switch (cmd) {
 166         case WDIOC_GETSUPPORT:
 167                 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
 168                         return -EFAULT;
 169         case WDIOC_GETSTATUS:
 170                 return put_user(0, p);
 171         case WDIOC_GETBOOTSTATUS:
 172                 /* XXX: something is clearing TSR */
 173                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 174                 /* returns CARDRESET if last reset was caused by the WDT */
 175                 return (tmp ? WDIOF_CARDRESET : 0);
 176         case WDIOC_SETOPTIONS:
 177                 if (get_user(tmp, p))
 178                         return -EINVAL;
 179                 if (tmp == WDIOS_ENABLECARD) {
 180                         booke_wdt_ping();
 181                         break;
 182                 } else
 183                         return -EINVAL;
 184                 return 0;
 185         case WDIOC_KEEPALIVE:
 186                 booke_wdt_ping();
 187                 return 0;
 188         case WDIOC_SETTIMEOUT:
 189                 if (get_user(tmp, p))
 190                         return -EFAULT;
 191 #ifdef  CONFIG_FSL_BOOKE
 192                 /* period of 1 gives the largest possible timeout */
 193                 if (tmp > period_to_sec(1))
 194                         return -EINVAL;
 195                 booke_wdt_period = sec_to_period(tmp);
 196 #else
 197                 booke_wdt_period = tmp;
 198 #endif
 199                 booke_wdt_set();
 200                 /* Fall */
 201         case WDIOC_GETTIMEOUT:
 202 #ifdef  CONFIG_FSL_BOOKE
 203                 return put_user(period_to_sec(booke_wdt_period), p);
 204 #else
 205                 return put_user(booke_wdt_period, p);
 206 #endif
 207         default:
 208                 return -ENOTTY;
 209         }
 210
 211         return 0;
 212 }
 213
 214 /* wdt_is_active stores wether or not the /dev/watchdog device is opened */
 215 static unsigned long wdt_is_active;
 216
 217 static int booke_wdt_open(struct inode *inode, struct file *file)
 218 {
 219         /* /dev/watchdog can only be opened once */
 220         if (test_and_set_bit(0, &wdt_is_active))
 221                 return -EBUSY;
 222
 223         spin_lock(&booke_wdt_lock);
 224         if (booke_wdt_enabled == 0) {
 225                 booke_wdt_enabled = 1;
 226                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 227                 pr_debug("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
 228                         period_to_sec(booke_wdt_period));
 229         }
 230         spin_unlock(&booke_wdt_lock);
 231
 232         return nonseekable_open(inode, file);
 233 }
 234
 235 static int booke_wdt_release(struct inode *inode, struct file *file)
 236 {
 237 #ifndef CONFIG_WATCHDOG_NOWAYOUT
 238         /* Normally, the watchdog is disabled when /dev/watchdog is closed, but
 239          * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
 240          * watchdog should remain enabled.  So we disable it only if
 241          * CONFIG_WATCHDOG_NOWAYOUT is not defined.
 242          */
 243         on_each_cpu(__booke_wdt_disable, NULL, 0);
 244         booke_wdt_enabled = 0;
 245         pr_debug("booke_wdt: watchdog disabled\n");
 246 #endif
 247
 248         clear_bit(0, &wdt_is_active);
 249
 250         return 0;
 251 }
 252
 253 static const struct file_operations booke_wdt_fops = {
 254         .owner = THIS_MODULE,
 255         .llseek = no_llseek,
 256         .write = booke_wdt_write,
 257         .unlocked_ioctl = booke_wdt_ioctl,
 258         .open = booke_wdt_open,
 259         .release = booke_wdt_release,
 260 };
 261
 262 static struct miscdevice booke_wdt_miscdev = {
 263         .minor = WATCHDOG_MINOR,
 264         .name = "watchdog",
 265         .fops = &booke_wdt_fops,
 266 };
 267
 268 static void __exit booke_wdt_exit(void)
 269 {
 270         misc_deregister(&booke_wdt_miscdev);
 271 }
 272
 273 static int __init booke_wdt_init(void)
 274 {
 275         int ret = 0;
 276
 277         pr_info("booke_wdt: powerpc book-e watchdog driver loaded\n");
 278         ident.firmware_version = cur_cpu_spec->pvr_value;
 279
 280         ret = misc_register(&booke_wdt_miscdev);
 281         if (ret) {
 282                 pr_err("booke_wdt: cannot register device (minor=%u, ret=%i)\n",
 283                        WATCHDOG_MINOR, ret);
 284                 return ret;
 285         }
 286
 287         spin_lock(&booke_wdt_lock);
 288         if (booke_wdt_enabled == 1) {
 289                 pr_info("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
 290                         period_to_sec(booke_wdt_period));
 291                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 292         }
 293         spin_unlock(&booke_wdt_lock);
 294
 295         return ret;
 296 }
 297
 298 module_init(booke_wdt_init);
 299 module_exit(booke_wdt_exit);
 300
 301 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
 302 MODULE_LICENSE("GPL");