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