drivers/watchdog/mpc8xxx_wdt.c

   1 /*
   2  * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
   3  *
   4  * Authors: Dave Updegraff <dave@cray.org>
   5  *          Kumar Gala <galak@kernel.crashing.org>
   6  *              Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
   7  *                              ..and from sc520_wdt
   8  * Copyright (c) 2008  MontaVista Software, Inc.
   9  *                     Anton Vorontsov <avorontsov@ru.mvista.com>
  10  *
  11  * Note: it appears that you can only actually ENABLE or DISABLE the thing
  12  * once after POR. Once enabled, you cannot disable, and vice versa.
  13  *
  14  * This program is free software; you can redistribute  it and/or modify it
  15  * under  the terms of  the GNU General  Public License as published by the
  16  * Free Software Foundation;  either version 2 of the  License, or (at your
  17  * option) any later version.
  18  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/fs.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/timer.h>
  26 #include <linux/miscdevice.h>
  27 #include <linux/of_platform.h>
  28 #include <linux/module.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/io.h>
  31 #include <linux/uaccess.h>
  32 #include <sysdev/fsl_soc.h>
  33
  34 struct mpc8xxx_wdt {
  35         __be32 res0;
  36         __be32 swcrr; /* System watchdog control register */
  37 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
  38 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
  39 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
  40 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
  41         __be32 swcnr; /* System watchdog count register */
  42         u8 res1[2];
  43         __be16 swsrr; /* System watchdog service register */
  44         u8 res2[0xF0];
  45 };
  46
  47 struct mpc8xxx_wdt_type {
  48         int prescaler;
  49         bool hw_enabled;
  50 };
  51
  52 static struct mpc8xxx_wdt __iomem *wd_base;
  53 static int mpc8xxx_wdt_init_late(void);
  54
  55 static u16 timeout = 0xffff;
  56 module_param(timeout, ushort, 0);
  57 MODULE_PARM_DESC(timeout,
  58         "Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
  59
  60 static bool reset = 1;
  61 module_param(reset, bool, 0);
  62 MODULE_PARM_DESC(reset,
  63         "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
  64
  65 static bool nowayout = WATCHDOG_NOWAYOUT;
  66 module_param(nowayout, bool, 0);
  67 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  68                  "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  69
  70 /*
  71  * We always prescale, but if someone really doesn't want to they can set this
  72  * to 0
  73  */
  74 static int prescale = 1;
  75 static unsigned int timeout_sec;
  76
  77 static unsigned long wdt_is_open;
  78 static DEFINE_SPINLOCK(wdt_spinlock);
  79
  80 static void mpc8xxx_wdt_keepalive(void)
  81 {
  82         /* Ping the WDT */
  83         spin_lock(&wdt_spinlock);
  84         out_be16(&wd_base->swsrr, 0x556c);
  85         out_be16(&wd_base->swsrr, 0xaa39);
  86         spin_unlock(&wdt_spinlock);
  87 }
  88
  89 static void mpc8xxx_wdt_timer_ping(unsigned long arg);
  90 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
  91
  92 static void mpc8xxx_wdt_timer_ping(unsigned long arg)
  93 {
  94         mpc8xxx_wdt_keepalive();
  95         /* We're pinging it twice faster than needed, just to be sure. */
  96         mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
  97 }
  98
  99 static void mpc8xxx_wdt_pr_warn(const char *msg)
 100 {
 101         pr_crit("%s, expect the %s soon!\n", msg,
 102                 reset ? "reset" : "machine check exception");
 103 }
 104
 105 static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
 106                                  size_t count, loff_t *ppos)
 107 {
 108         if (count)
 109                 mpc8xxx_wdt_keepalive();
 110         return count;
 111 }
 112
 113 static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
 114 {
 115         u32 tmp = SWCRR_SWEN;
 116         if (test_and_set_bit(0, &wdt_is_open))
 117                 return -EBUSY;
 118
 119         /* Once we start the watchdog we can't stop it */
 120         if (nowayout)
 121                 __module_get(THIS_MODULE);
 122
 123         /* Good, fire up the show */
 124         if (prescale)
 125                 tmp |= SWCRR_SWPR;
 126         if (reset)
 127                 tmp |= SWCRR_SWRI;
 128
 129         tmp |= timeout << 16;
 130
 131         out_be32(&wd_base->swcrr, tmp);
 132
 133         del_timer_sync(&wdt_timer);
 134
 135         return nonseekable_open(inode, file);
 136 }
 137
 138 static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
 139 {
 140         if (!nowayout)
 141                 mpc8xxx_wdt_timer_ping(0);
 142         else
 143                 mpc8xxx_wdt_pr_warn("watchdog closed");
 144         clear_bit(0, &wdt_is_open);
 145         return 0;
 146 }
 147
 148 static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
 149                                                         unsigned long arg)
 150 {
 151         void __user *argp = (void __user *)arg;
 152         int __user *p = argp;
 153         static const struct watchdog_info ident = {
 154                 .options = WDIOF_KEEPALIVEPING,
 155                 .firmware_version = 1,
 156                 .identity = "MPC8xxx",
 157         };
 158
 159         switch (cmd) {
 160         case WDIOC_GETSUPPORT:
 161                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 162         case WDIOC_GETSTATUS:
 163         case WDIOC_GETBOOTSTATUS:
 164                 return put_user(0, p);
 165         case WDIOC_KEEPALIVE:
 166                 mpc8xxx_wdt_keepalive();
 167                 return 0;
 168         case WDIOC_GETTIMEOUT:
 169                 return put_user(timeout_sec, p);
 170         default:
 171                 return -ENOTTY;
 172         }
 173 }
 174
 175 static const struct file_operations mpc8xxx_wdt_fops = {
 176         .owner          = THIS_MODULE,
 177         .llseek         = no_llseek,
 178         .write          = mpc8xxx_wdt_write,
 179         .unlocked_ioctl = mpc8xxx_wdt_ioctl,
 180         .open           = mpc8xxx_wdt_open,
 181         .release        = mpc8xxx_wdt_release,
 182 };
 183
 184 static struct miscdevice mpc8xxx_wdt_miscdev = {
 185         .minor  = WATCHDOG_MINOR,
 186         .name   = "watchdog",
 187         .fops   = &mpc8xxx_wdt_fops,
 188 };
 189
 190 static const struct of_device_id mpc8xxx_wdt_match[];
 191 static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
 192 {
 193         int ret;
 194         const struct of_device_id *match;
 195         struct device_node *np = ofdev->dev.of_node;
 196         const struct mpc8xxx_wdt_type *wdt_type;
 197         u32 freq = fsl_get_sys_freq();
 198         bool enabled;
 199
 200         match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
 201         if (!match)
 202                 return -EINVAL;
 203         wdt_type = match->data;
 204
 205         if (!freq || freq == -1)
 206                 return -EINVAL;
 207
 208         wd_base = of_iomap(np, 0);
 209         if (!wd_base)
 210                 return -ENOMEM;
 211
 212         enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
 213         if (!enabled && wdt_type->hw_enabled) {
 214                 pr_info("could not be enabled in software\n");
 215                 ret = -ENOSYS;
 216                 goto err_unmap;
 217         }
 218
 219         /* Calculate the timeout in seconds */
 220         if (prescale)
 221                 timeout_sec = (timeout * wdt_type->prescaler) / freq;
 222         else
 223                 timeout_sec = timeout / freq;
 224
 225 #ifdef MODULE
 226         ret = mpc8xxx_wdt_init_late();
 227         if (ret)
 228                 goto err_unmap;
 229 #endif
 230
 231         pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
 232                 reset ? "reset" : "interrupt", timeout, timeout_sec);
 233
 234         /*
 235          * If the watchdog was previously enabled or we're running on
 236          * MPC8xxx, we should ping the wdt from the kernel until the
 237          * userspace handles it.
 238          */
 239         if (enabled)
 240                 mpc8xxx_wdt_timer_ping(0);
 241         return 0;
 242 err_unmap:
 243         iounmap(wd_base);
 244         wd_base = NULL;
 245         return ret;
 246 }
 247
 248 static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
 249 {
 250         mpc8xxx_wdt_pr_warn("watchdog removed");
 251         del_timer_sync(&wdt_timer);
 252         misc_deregister(&mpc8xxx_wdt_miscdev);
 253         iounmap(wd_base);
 254
 255         return 0;
 256 }
 257
 258 static const struct of_device_id mpc8xxx_wdt_match[] = {
 259         {
 260                 .compatible = "mpc83xx_wdt",
 261                 .data = &(struct mpc8xxx_wdt_type) {
 262                         .prescaler = 0x10000,
 263                 },
 264         },
 265         {
 266                 .compatible = "fsl,mpc8610-wdt",
 267                 .data = &(struct mpc8xxx_wdt_type) {
 268                         .prescaler = 0x10000,
 269                         .hw_enabled = true,
 270                 },
 271         },
 272         {
 273                 .compatible = "fsl,mpc823-wdt",
 274                 .data = &(struct mpc8xxx_wdt_type) {
 275                         .prescaler = 0x800,
 276                 },
 277         },
 278         {},
 279 };
 280 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
 281
 282 static struct platform_driver mpc8xxx_wdt_driver = {
 283         .probe          = mpc8xxx_wdt_probe,
 284         .remove         = mpc8xxx_wdt_remove,
 285         .driver = {
 286                 .name = "mpc8xxx_wdt",
 287                 .owner = THIS_MODULE,
 288                 .of_match_table = mpc8xxx_wdt_match,
 289         },
 290 };
 291
 292 /*
 293  * We do wdt initialization in two steps: arch_initcall probes the wdt
 294  * very early to start pinging the watchdog (misc devices are not yet
 295  * available), and later module_init() just registers the misc device.
 296  */
 297 static int mpc8xxx_wdt_init_late(void)
 298 {
 299         int ret;
 300
 301         if (!wd_base)
 302                 return -ENODEV;
 303
 304         ret = misc_register(&mpc8xxx_wdt_miscdev);
 305         if (ret) {
 306                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 307                        WATCHDOG_MINOR, ret);
 308                 return ret;
 309         }
 310         return 0;
 311 }
 312 #ifndef MODULE
 313 module_init(mpc8xxx_wdt_init_late);
 314 #endif
 315
 316 static int __init mpc8xxx_wdt_init(void)
 317 {
 318         return platform_driver_register(&mpc8xxx_wdt_driver);
 319 }
 320 arch_initcall(mpc8xxx_wdt_init);
 321
 322 static void __exit mpc8xxx_wdt_exit(void)
 323 {
 324         platform_driver_unregister(&mpc8xxx_wdt_driver);
 325 }
 326 module_exit(mpc8xxx_wdt_exit);
 327
 328 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
 329 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
 330                    "uProcessors");
 331 MODULE_LICENSE("GPL");
 332 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);