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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  16
  17 #include <linux/module.h>
  18 #include <linux/fs.h>
  19 #include <linux/smp.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/notifier.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/uaccess.h>
  24
  25 #include <asm/reg_booke.h>
  26 #include <asm/system.h>
  27 #include <asm/time.h>
  28 #include <asm/div64.h>
  29
  30 /* If the kernel parameter wdt=1, the watchdog will be enabled at boot.
  31  * Also, the wdt_period sets the watchdog timer period timeout.
  32  * For E500 cpus the wdt_period sets which bit changing from 0->1 will
  33  * trigger a watchog timeout. This watchdog timeout will occur 3 times, the
  34  * first time nothing will happen, the second time a watchdog exception will
  35  * occur, and the final time the board will reset.
  36  */
  37
  38 u32 booke_wdt_enabled;
  39 u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT;
  40
  41 #ifdef  CONFIG_FSL_BOOKE
  42 #define WDTP(x)         ((((x)&0x3)<<30)|(((x)&0x3c)<<15))
  43 #define WDTP_MASK       (WDTP(0x3f))
  44 #else
  45 #define WDTP(x)         (TCR_WP(x))
  46 #define WDTP_MASK       (TCR_WP_MASK)
  47 #endif
  48
  49 static DEFINE_SPINLOCK(booke_wdt_lock);
  50
  51 /* For the specified period, determine the number of seconds
  52  * corresponding to the reset time.  There will be a watchdog
  53  * exception at approximately 3/5 of this time.
  54  *
  55  * The formula to calculate this is given by:
  56  * 2.5 * (2^(63-period+1)) / timebase_freq
  57  *
  58  * In order to simplify things, we assume that period is
  59  * at least 1.  This will still result in a very long timeout.
  60  */
  61 static unsigned long long period_to_sec(unsigned int period)
  62 {
  63         unsigned long long tmp = 1ULL << (64 - period);
  64         unsigned long tmp2 = ppc_tb_freq;
  65
  66         /* tmp may be a very large number and we don't want to overflow,
  67          * so divide the timebase freq instead of multiplying tmp
  68          */
  69         tmp2 = tmp2 / 5 * 2;
  70
  71         do_div(tmp, tmp2);
  72         return tmp;
  73 }
  74
  75 /*
  76  * This procedure will find the highest period which will give a timeout
  77  * greater than the one required. e.g. for a bus speed of 66666666 and
  78  * and a parameter of 2 secs, then this procedure will return a value of 38.
  79  */
  80 static unsigned int sec_to_period(unsigned int secs)
  81 {
  82         unsigned int period;
  83         for (period = 63; period > 0; period--) {
  84                 if (period_to_sec(period) >= secs)
  85                         return period;
  86         }
  87         return 0;
  88 }
  89
  90 static void __booke_wdt_set(void *data)
  91 {
  92         u32 val;
  93
  94         val = mfspr(SPRN_TCR);
  95         val &= ~WDTP_MASK;
  96         val |= WDTP(booke_wdt_period);
  97
  98         mtspr(SPRN_TCR, val);
  99 }
 100
 101 static void booke_wdt_set(void)
 102 {
 103         on_each_cpu(__booke_wdt_set, NULL, 0);
 104 }
 105
 106 static void __booke_wdt_ping(void *data)
 107 {
 108         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
 109 }
 110
 111 static void booke_wdt_ping(void)
 112 {
 113         on_each_cpu(__booke_wdt_ping, NULL, 0);
 114 }
 115
 116 static void __booke_wdt_enable(void *data)
 117 {
 118         u32 val;
 119
 120         /* clear status before enabling watchdog */
 121         __booke_wdt_ping(NULL);
 122         val = mfspr(SPRN_TCR);
 123         val &= ~WDTP_MASK;
 124         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
 125
 126         mtspr(SPRN_TCR, val);
 127 }
 128
 129 /**
 130  * booke_wdt_disable - disable the watchdog on the given CPU
 131  *
 132  * This function is called on each CPU.  It disables the watchdog on that CPU.
 133  *
 134  * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
 135  * effectively disable the watchdog by setting its period to the maximum value.
 136  */
 137 static void __booke_wdt_disable(void *data)
 138 {
 139         u32 val;
 140
 141         val = mfspr(SPRN_TCR);
 142         val &= ~(TCR_WIE | WDTP_MASK);
 143         mtspr(SPRN_TCR, val);
 144
 145         /* clear status to make sure nothing is pending */
 146         __booke_wdt_ping(NULL);
 147
 148 }
 149
 150 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
 151                                 size_t count, loff_t *ppos)
 152 {
 153         booke_wdt_ping();
 154         return count;
 155 }
 156
 157 static struct watchdog_info ident = {
 158         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 159         .identity = "PowerPC Book-E Watchdog",
 160 };
 161
 162 static long booke_wdt_ioctl(struct file *file,
 163                                 unsigned int cmd, unsigned long arg)
 164 {
 165         u32 tmp = 0;
 166         u32 __user *p = (u32 __user *)arg;
 167
 168         switch (cmd) {
 169         case WDIOC_GETSUPPORT:
 170                 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
 171                         return -EFAULT;
 172         case WDIOC_GETSTATUS:
 173                 return put_user(0, p);
 174         case WDIOC_GETBOOTSTATUS:
 175                 /* XXX: something is clearing TSR */
 176                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 177                 /* returns CARDRESET if last reset was caused by the WDT */
 178                 return (tmp ? WDIOF_CARDRESET : 0);
 179         case WDIOC_SETOPTIONS:
 180                 if (get_user(tmp, p))
 181                         return -EINVAL;
 182                 if (tmp == WDIOS_ENABLECARD) {
 183                         booke_wdt_ping();
 184                         break;
 185                 } else
 186                         return -EINVAL;
 187                 return 0;
 188         case WDIOC_KEEPALIVE:
 189                 booke_wdt_ping();
 190                 return 0;
 191         case WDIOC_SETTIMEOUT:
 192                 if (get_user(tmp, p))
 193                         return -EFAULT;
 194 #ifdef  CONFIG_FSL_BOOKE
 195                 /* period of 1 gives the largest possible timeout */
 196                 if (tmp > period_to_sec(1))
 197                         return -EINVAL;
 198                 booke_wdt_period = sec_to_period(tmp);
 199 #else
 200                 booke_wdt_period = tmp;
 201 #endif
 202                 booke_wdt_set();
 203                 /* Fall */
 204         case WDIOC_GETTIMEOUT:
 205 #ifdef  CONFIG_FSL_BOOKE
 206                 return put_user(period_to_sec(booke_wdt_period), p);
 207 #else
 208                 return put_user(booke_wdt_period, p);
 209 #endif
 210         default:
 211                 return -ENOTTY;
 212         }
 213
 214         return 0;
 215 }
 216
 217 /* wdt_is_active stores wether or not the /dev/watchdog device is opened */
 218 static unsigned long wdt_is_active;
 219
 220 static int booke_wdt_open(struct inode *inode, struct file *file)
 221 {
 222         /* /dev/watchdog can only be opened once */
 223         if (test_and_set_bit(0, &wdt_is_active))
 224                 return -EBUSY;
 225
 226         spin_lock(&booke_wdt_lock);
 227         if (booke_wdt_enabled == 0) {
 228                 booke_wdt_enabled = 1;
 229                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 230                 pr_debug("watchdog enabled (timeout = %llu sec)\n",
 231                          period_to_sec(booke_wdt_period));
 232         }
 233         spin_unlock(&booke_wdt_lock);
 234
 235         return nonseekable_open(inode, file);
 236 }
 237
 238 static int booke_wdt_release(struct inode *inode, struct file *file)
 239 {
 240 #ifndef CONFIG_WATCHDOG_NOWAYOUT
 241         /* Normally, the watchdog is disabled when /dev/watchdog is closed, but
 242          * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
 243          * watchdog should remain enabled.  So we disable it only if
 244          * CONFIG_WATCHDOG_NOWAYOUT is not defined.
 245          */
 246         on_each_cpu(__booke_wdt_disable, NULL, 0);
 247         booke_wdt_enabled = 0;
 248         pr_debug("watchdog disabled\n");
 249 #endif
 250
 251         clear_bit(0, &wdt_is_active);
 252
 253         return 0;
 254 }
 255
 256 static const struct file_operations booke_wdt_fops = {
 257         .owner = THIS_MODULE,
 258         .llseek = no_llseek,
 259         .write = booke_wdt_write,
 260         .unlocked_ioctl = booke_wdt_ioctl,
 261         .open = booke_wdt_open,
 262         .release = booke_wdt_release,
 263 };
 264
 265 static struct miscdevice booke_wdt_miscdev = {
 266         .minor = WATCHDOG_MINOR,
 267         .name = "watchdog",
 268         .fops = &booke_wdt_fops,
 269 };
 270
 271 static void __exit booke_wdt_exit(void)
 272 {
 273         misc_deregister(&booke_wdt_miscdev);
 274 }
 275
 276 static int __init booke_wdt_init(void)
 277 {
 278         int ret = 0;
 279
 280         pr_info("powerpc book-e watchdog driver loaded\n");
 281         ident.firmware_version = cur_cpu_spec->pvr_value;
 282
 283         ret = misc_register(&booke_wdt_miscdev);
 284         if (ret) {
 285                 pr_err("cannot register device (minor=%u, ret=%i)\n",
 286                        WATCHDOG_MINOR, ret);
 287                 return ret;
 288         }
 289
 290         spin_lock(&booke_wdt_lock);
 291         if (booke_wdt_enabled == 1) {
 292                 pr_info("watchdog enabled (timeout = %llu sec)\n",
 293                         period_to_sec(booke_wdt_period));
 294                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 295         }
 296         spin_unlock(&booke_wdt_lock);
 297
 298         return ret;
 299 }
 300
 301 module_init(booke_wdt_init);
 302 module_exit(booke_wdt_exit);
 303
 304 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
 305 MODULE_LICENSE("GPL");