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