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