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