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
  77 static DEFINE_SPINLOCK(wdt_spinlock);
  78
  79 static void mpc8xxx_wdt_keepalive(void)
  80 {
  81         /* Ping the WDT */
  82         spin_lock(&wdt_spinlock);
  83         out_be16(&wd_base->swsrr, 0x556c);
  84         out_be16(&wd_base->swsrr, 0xaa39);
  85         spin_unlock(&wdt_spinlock);
  86 }
  87
  88 static struct watchdog_device mpc8xxx_wdt_dev;
  89 static void mpc8xxx_wdt_timer_ping(unsigned long arg);
  90 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0,
  91                 (unsigned long)&mpc8xxx_wdt_dev);
  92
  93 static void mpc8xxx_wdt_timer_ping(unsigned long arg)
  94 {
  95         struct watchdog_device *w = (struct watchdog_device *)arg;
  96
  97         mpc8xxx_wdt_keepalive();
  98         /* We're pinging it twice faster than needed, just to be sure. */
  99         mod_timer(&wdt_timer, jiffies + HZ * w->timeout / 2);
 100 }
 101
 102 static int mpc8xxx_wdt_start(struct watchdog_device *w)
 103 {
 104         u32 tmp = SWCRR_SWEN;
 105
 106         /* Good, fire up the show */
 107         if (prescale)
 108                 tmp |= SWCRR_SWPR;
 109         if (reset)
 110                 tmp |= SWCRR_SWRI;
 111
 112         tmp |= timeout << 16;
 113
 114         out_be32(&wd_base->swcrr, tmp);
 115
 116         del_timer_sync(&wdt_timer);
 117
 118         return 0;
 119 }
 120
 121 static int mpc8xxx_wdt_ping(struct watchdog_device *w)
 122 {
 123         mpc8xxx_wdt_keepalive();
 124         return 0;
 125 }
 126
 127 static int mpc8xxx_wdt_stop(struct watchdog_device *w)
 128 {
 129         mod_timer(&wdt_timer, jiffies);
 130         return 0;
 131 }
 132
 133 static struct watchdog_info mpc8xxx_wdt_info = {
 134         .options = WDIOF_KEEPALIVEPING,
 135         .firmware_version = 1,
 136         .identity = "MPC8xxx",
 137 };
 138
 139 static struct watchdog_ops mpc8xxx_wdt_ops = {
 140         .owner = THIS_MODULE,
 141         .start = mpc8xxx_wdt_start,
 142         .ping = mpc8xxx_wdt_ping,
 143         .stop = mpc8xxx_wdt_stop,
 144 };
 145
 146 static struct watchdog_device mpc8xxx_wdt_dev = {
 147         .info = &mpc8xxx_wdt_info,
 148         .ops = &mpc8xxx_wdt_ops,
 149 };
 150
 151 static const struct of_device_id mpc8xxx_wdt_match[];
 152 static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
 153 {
 154         int ret;
 155         const struct of_device_id *match;
 156         struct device_node *np = ofdev->dev.of_node;
 157         const struct mpc8xxx_wdt_type *wdt_type;
 158         u32 freq = fsl_get_sys_freq();
 159         bool enabled;
 160         unsigned int timeout_sec;
 161
 162         match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
 163         if (!match)
 164                 return -EINVAL;
 165         wdt_type = match->data;
 166
 167         if (!freq || freq == -1)
 168                 return -EINVAL;
 169
 170         wd_base = of_iomap(np, 0);
 171         if (!wd_base)
 172                 return -ENOMEM;
 173
 174         enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
 175         if (!enabled && wdt_type->hw_enabled) {
 176                 pr_info("could not be enabled in software\n");
 177                 ret = -ENOSYS;
 178                 goto err_unmap;
 179         }
 180
 181         /* Calculate the timeout in seconds */
 182         if (prescale)
 183                 timeout_sec = (timeout * wdt_type->prescaler) / freq;
 184         else
 185                 timeout_sec = timeout / freq;
 186
 187         mpc8xxx_wdt_dev.timeout = timeout_sec;
 188 #ifdef MODULE
 189         ret = mpc8xxx_wdt_init_late();
 190         if (ret)
 191                 goto err_unmap;
 192 #endif
 193
 194         pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
 195                 reset ? "reset" : "interrupt", timeout, timeout_sec);
 196
 197         /*
 198          * If the watchdog was previously enabled or we're running on
 199          * MPC8xxx, we should ping the wdt from the kernel until the
 200          * userspace handles it.
 201          */
 202         if (enabled)
 203                 mod_timer(&wdt_timer, jiffies);
 204         return 0;
 205 err_unmap:
 206         iounmap(wd_base);
 207         wd_base = NULL;
 208         return ret;
 209 }
 210
 211 static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
 212 {
 213         pr_crit("Watchdog removed, expect the %s soon!\n",
 214                 reset ? "reset" : "machine check exception");
 215         del_timer_sync(&wdt_timer);
 216         watchdog_unregister_device(&mpc8xxx_wdt_dev);
 217         iounmap(wd_base);
 218
 219         return 0;
 220 }
 221
 222 static const struct of_device_id mpc8xxx_wdt_match[] = {
 223         {
 224                 .compatible = "mpc83xx_wdt",
 225                 .data = &(struct mpc8xxx_wdt_type) {
 226                         .prescaler = 0x10000,
 227                 },
 228         },
 229         {
 230                 .compatible = "fsl,mpc8610-wdt",
 231                 .data = &(struct mpc8xxx_wdt_type) {
 232                         .prescaler = 0x10000,
 233                         .hw_enabled = true,
 234                 },
 235         },
 236         {
 237                 .compatible = "fsl,mpc823-wdt",
 238                 .data = &(struct mpc8xxx_wdt_type) {
 239                         .prescaler = 0x800,
 240                         .hw_enabled = true,
 241                 },
 242         },
 243         {},
 244 };
 245 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
 246
 247 static struct platform_driver mpc8xxx_wdt_driver = {
 248         .probe          = mpc8xxx_wdt_probe,
 249         .remove         = mpc8xxx_wdt_remove,
 250         .driver = {
 251                 .name = "mpc8xxx_wdt",
 252                 .of_match_table = mpc8xxx_wdt_match,
 253         },
 254 };
 255
 256 /*
 257  * We do wdt initialization in two steps: arch_initcall probes the wdt
 258  * very early to start pinging the watchdog (misc devices are not yet
 259  * available), and later module_init() just registers the misc device.
 260  */
 261 static int mpc8xxx_wdt_init_late(void)
 262 {
 263         int ret;
 264
 265         if (!wd_base)
 266                 return -ENODEV;
 267
 268         watchdog_set_nowayout(&mpc8xxx_wdt_dev, nowayout);
 269
 270         ret = watchdog_register_device(&mpc8xxx_wdt_dev);
 271         if (ret) {
 272                 pr_err("cannot register watchdog device (err=%d)\n", ret);
 273                 return ret;
 274         }
 275         return 0;
 276 }
 277 #ifndef MODULE
 278 module_init(mpc8xxx_wdt_init_late);
 279 #endif
 280
 281 static int __init mpc8xxx_wdt_init(void)
 282 {
 283         return platform_driver_register(&mpc8xxx_wdt_driver);
 284 }
 285 arch_initcall(mpc8xxx_wdt_init);
 286
 287 static void __exit mpc8xxx_wdt_exit(void)
 288 {
 289         platform_driver_unregister(&mpc8xxx_wdt_driver);
 290 }
 291 module_exit(mpc8xxx_wdt_exit);
 292
 293 MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
 294 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
 295                    "uProcessors");
 296 MODULE_LICENSE("GPL");