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/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_set(void *data)
  89 {
  90         u32 val;
  91
  92         val = mfspr(SPRN_TCR);
  93         val &= ~WDTP_MASK;
  94         val |= WDTP(booke_wdt_period);
  95
  96         mtspr(SPRN_TCR, val);
  97 }
  98
  99 static void booke_wdt_set(void)
 100 {
 101         on_each_cpu(__booke_wdt_set, NULL, 0);
 102 }
 103
 104 static void __booke_wdt_ping(void *data)
 105 {
 106         mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
 107 }
 108
 109 static void booke_wdt_ping(void)
 110 {
 111         on_each_cpu(__booke_wdt_ping, NULL, 0);
 112 }
 113
 114 static void __booke_wdt_enable(void *data)
 115 {
 116         u32 val;
 117
 118         /* clear status before enabling watchdog */
 119         __booke_wdt_ping(NULL);
 120         val = mfspr(SPRN_TCR);
 121         val &= ~WDTP_MASK;
 122         val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
 123
 124         mtspr(SPRN_TCR, val);
 125 }
 126
 127 /**
 128  * booke_wdt_disable - disable the watchdog on the given CPU
 129  *
 130  * This function is called on each CPU.  It disables the watchdog on that CPU.
 131  *
 132  * TCR[WRC] cannot be changed once it has been set to non-zero, but we can
 133  * effectively disable the watchdog by setting its period to the maximum value.
 134  */
 135 static void __booke_wdt_disable(void *data)
 136 {
 137         u32 val;
 138
 139         val = mfspr(SPRN_TCR);
 140         val &= ~(TCR_WIE | WDTP_MASK);
 141         mtspr(SPRN_TCR, val);
 142
 143         /* clear status to make sure nothing is pending */
 144         __booke_wdt_ping(NULL);
 145
 146 }
 147
 148 static ssize_t booke_wdt_write(struct file *file, const char __user *buf,
 149                                 size_t count, loff_t *ppos)
 150 {
 151         booke_wdt_ping();
 152         return count;
 153 }
 154
 155 static struct watchdog_info ident = {
 156         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 157         .identity = "PowerPC Book-E Watchdog",
 158 };
 159
 160 static long booke_wdt_ioctl(struct file *file,
 161                                 unsigned int cmd, unsigned long arg)
 162 {
 163         u32 tmp = 0;
 164         u32 __user *p = (u32 __user *)arg;
 165
 166         switch (cmd) {
 167         case WDIOC_GETSUPPORT:
 168                 if (copy_to_user((void *)arg, &ident, sizeof(ident)))
 169                         return -EFAULT;
 170         case WDIOC_GETSTATUS:
 171                 return put_user(0, p);
 172         case WDIOC_GETBOOTSTATUS:
 173                 /* XXX: something is clearing TSR */
 174                 tmp = mfspr(SPRN_TSR) & TSR_WRS(3);
 175                 /* returns CARDRESET if last reset was caused by the WDT */
 176                 return (tmp ? WDIOF_CARDRESET : 0);
 177         case WDIOC_SETOPTIONS:
 178                 if (get_user(tmp, p))
 179                         return -EINVAL;
 180                 if (tmp == WDIOS_ENABLECARD) {
 181                         booke_wdt_ping();
 182                         break;
 183                 } else
 184                         return -EINVAL;
 185                 return 0;
 186         case WDIOC_KEEPALIVE:
 187                 booke_wdt_ping();
 188                 return 0;
 189         case WDIOC_SETTIMEOUT:
 190                 if (get_user(tmp, p))
 191                         return -EFAULT;
 192 #ifdef  CONFIG_FSL_BOOKE
 193                 /* period of 1 gives the largest possible timeout */
 194                 if (tmp > period_to_sec(1))
 195                         return -EINVAL;
 196                 booke_wdt_period = sec_to_period(tmp);
 197 #else
 198                 booke_wdt_period = tmp;
 199 #endif
 200                 booke_wdt_set();
 201                 return 0;
 202         case WDIOC_GETTIMEOUT:
 203                 return put_user(booke_wdt_period, p);
 204         default:
 205                 return -ENOTTY;
 206         }
 207
 208         return 0;
 209 }
 210
 211 /* wdt_is_active stores wether or not the /dev/watchdog device is opened */
 212 static unsigned long wdt_is_active;
 213
 214 static int booke_wdt_open(struct inode *inode, struct file *file)
 215 {
 216         /* /dev/watchdog can only be opened once */
 217         if (test_and_set_bit(0, &wdt_is_active))
 218                 return -EBUSY;
 219
 220         spin_lock(&booke_wdt_lock);
 221         if (booke_wdt_enabled == 0) {
 222                 booke_wdt_enabled = 1;
 223                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 224                 pr_debug("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
 225                         period_to_sec(booke_wdt_period));
 226         }
 227         spin_unlock(&booke_wdt_lock);
 228
 229         return nonseekable_open(inode, file);
 230 }
 231
 232 static int booke_wdt_release(struct inode *inode, struct file *file)
 233 {
 234 #ifndef CONFIG_WATCHDOG_NOWAYOUT
 235         /* Normally, the watchdog is disabled when /dev/watchdog is closed, but
 236          * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the
 237          * watchdog should remain enabled.  So we disable it only if
 238          * CONFIG_WATCHDOG_NOWAYOUT is not defined.
 239          */
 240         on_each_cpu(__booke_wdt_disable, NULL, 0);
 241         booke_wdt_enabled = 0;
 242         pr_debug("booke_wdt: watchdog disabled\n");
 243 #endif
 244
 245         clear_bit(0, &wdt_is_active);
 246
 247         return 0;
 248 }
 249
 250 static const struct file_operations booke_wdt_fops = {
 251         .owner = THIS_MODULE,
 252         .llseek = no_llseek,
 253         .write = booke_wdt_write,
 254         .unlocked_ioctl = booke_wdt_ioctl,
 255         .open = booke_wdt_open,
 256         .release = booke_wdt_release,
 257 };
 258
 259 static struct miscdevice booke_wdt_miscdev = {
 260         .minor = WATCHDOG_MINOR,
 261         .name = "watchdog",
 262         .fops = &booke_wdt_fops,
 263 };
 264
 265 static void __exit booke_wdt_exit(void)
 266 {
 267         misc_deregister(&booke_wdt_miscdev);
 268 }
 269
 270 static int __init booke_wdt_init(void)
 271 {
 272         int ret = 0;
 273
 274         pr_info("booke_wdt: powerpc book-e watchdog driver loaded\n");
 275         ident.firmware_version = cur_cpu_spec->pvr_value;
 276
 277         ret = misc_register(&booke_wdt_miscdev);
 278         if (ret) {
 279                 pr_err("booke_wdt: cannot register device (minor=%u, ret=%i)\n",
 280                        WATCHDOG_MINOR, ret);
 281                 return ret;
 282         }
 283
 284         spin_lock(&booke_wdt_lock);
 285         if (booke_wdt_enabled == 1) {
 286                 pr_info("booke_wdt: watchdog enabled (timeout = %llu sec)\n",
 287                         period_to_sec(booke_wdt_period));
 288                 on_each_cpu(__booke_wdt_enable, NULL, 0);
 289         }
 290         spin_unlock(&booke_wdt_lock);
 291
 292         return ret;
 293 }
 294
 295 module_init(booke_wdt_init);
 296 module_exit(booke_wdt_exit);
 297
 298 MODULE_DESCRIPTION("PowerPC Book-E watchdog driver");
 299 MODULE_LICENSE("GPL");