linux/drivers/watchdog/omap_wdt.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * omap_wdt.c
   4 *
   5 * Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
   6 *
   7 * Author: MontaVista Software, Inc.
   8 *       <gdavis@mvista.com> or <source@mvista.com>
   9 *
  10 * 2003 (c) MontaVista Software, Inc.
  11 *
  12 * History:
  13 *
  14 * 20030527: George G. Davis <gdavis@mvista.com>
  15 *      Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
  16 *      (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
  17 *      Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
  18 *
  19 * Copyright (c) 2004 Texas Instruments.
  20 *      1. Modified to support OMAP1610 32-KHz watchdog timer
  21 *      2. Ported to 2.6 kernel
  22 *
  23 * Copyright (c) 2005 David Brownell
  24 *      Use the driver model and standard identifiers; handle bigger timeouts.
  25 */
  26
  27#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  28
  29#include <linux/module.h>
  30#include <linux/mod_devicetable.h>
  31#include <linux/types.h>
  32#include <linux/kernel.h>
  33#include <linux/mm.h>
  34#include <linux/watchdog.h>
  35#include <linux/reboot.h>
  36#include <linux/err.h>
  37#include <linux/platform_device.h>
  38#include <linux/moduleparam.h>
  39#include <linux/io.h>
  40#include <linux/slab.h>
  41#include <linux/pm_runtime.h>
  42#include <linux/platform_data/omap-wd-timer.h>
  43
  44#include "omap_wdt.h"
  45
  46static bool nowayout = WATCHDOG_NOWAYOUT;
  47module_param(nowayout, bool, 0);
  48MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  49        "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  50
  51static unsigned timer_margin;
  52module_param(timer_margin, uint, 0);
  53MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");
  54
  55#define to_omap_wdt_dev(_wdog)  container_of(_wdog, struct omap_wdt_dev, wdog)
  56
  57static bool early_enable;
  58module_param(early_enable, bool, 0);
  59MODULE_PARM_DESC(early_enable,
  60        "Watchdog is started on module insertion (default=0)");
  61
  62struct omap_wdt_dev {
  63        struct watchdog_device wdog;
  64        void __iomem    *base;          /* physical */
  65        struct device   *dev;
  66        bool            omap_wdt_users;
  67        int             wdt_trgr_pattern;
  68        struct mutex    lock;           /* to avoid races with PM */
  69};
  70
  71static void omap_wdt_reload(struct omap_wdt_dev *wdev)
  72{
  73        void __iomem    *base = wdev->base;
  74
  75        /* wait for posted write to complete */
  76        while ((readl_relaxed(base + OMAP_WATCHDOG_WPS)) & 0x08)
  77                cpu_relax();
  78
  79        wdev->wdt_trgr_pattern = ~wdev->wdt_trgr_pattern;
  80        writel_relaxed(wdev->wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));
  81
  82        /* wait for posted write to complete */
  83        while ((readl_relaxed(base + OMAP_WATCHDOG_WPS)) & 0x08)
  84                cpu_relax();
  85        /* reloaded WCRR from WLDR */
  86}
  87
  88static void omap_wdt_enable(struct omap_wdt_dev *wdev)
  89{
  90        void __iomem *base = wdev->base;
  91
  92        /* Sequence to enable the watchdog */
  93        writel_relaxed(0xBBBB, base + OMAP_WATCHDOG_SPR);
  94        while ((readl_relaxed(base + OMAP_WATCHDOG_WPS)) & 0x10)
  95                cpu_relax();
  96
  97        writel_relaxed(0x4444, base + OMAP_WATCHDOG_SPR);
  98        while ((readl_relaxed(base + OMAP_WATCHDOG_WPS)) & 0x10)
  99                cpu_relax();
 100}
 101
 102static void omap_wdt_disable(struct omap_wdt_dev *wdev)
 103{
 104        void __iomem *base = wdev->base;
 105
 106        /* sequence required to disable watchdog */
 107        writel_relaxed(0xAAAA, base + OMAP_WATCHDOG_SPR);       /* TIMER_MODE */
 108        while (readl_relaxed(base + OMAP_WATCHDOG_WPS) & 0x10)
 109                cpu_relax();
 110
 111        writel_relaxed(0x5555, base + OMAP_WATCHDOG_SPR);       /* TIMER_MODE */
 112        while (readl_relaxed(base + OMAP_WATCHDOG_WPS) & 0x10)
 113                cpu_relax();
 114}
 115
 116static void omap_wdt_set_timer(struct omap_wdt_dev *wdev,
 117                                   unsigned int timeout)
 118{
 119        u32 pre_margin = GET_WLDR_VAL(timeout);
 120        void __iomem *base = wdev->base;
 121
 122        /* just count up at 32 KHz */
 123        while (readl_relaxed(base + OMAP_WATCHDOG_WPS) & 0x04)
 124                cpu_relax();
 125
 126        writel_relaxed(pre_margin, base + OMAP_WATCHDOG_LDR);
 127        while (readl_relaxed(base + OMAP_WATCHDOG_WPS) & 0x04)
 128                cpu_relax();
 129}
 130
 131static int omap_wdt_start(struct watchdog_device *wdog)
 132{
 133        struct omap_wdt_dev *wdev = to_omap_wdt_dev(wdog);
 134        void __iomem *base = wdev->base;
 135
 136        mutex_lock(&wdev->lock);
 137
 138        wdev->omap_wdt_users = true;
 139
 140        pm_runtime_get_sync(wdev->dev);
 141
 142        /*
 143         * Make sure the watchdog is disabled. This is unfortunately required
 144         * because writing to various registers with the watchdog running has no
 145         * effect.
 146         */
 147        omap_wdt_disable(wdev);
 148
 149        /* initialize prescaler */
 150        while (readl_relaxed(base + OMAP_WATCHDOG_WPS) & 0x01)
 151                cpu_relax();
 152
 153        writel_relaxed((1 << 5) | (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
 154        while (readl_relaxed(base + OMAP_WATCHDOG_WPS) & 0x01)
 155                cpu_relax();
 156
 157        omap_wdt_set_timer(wdev, wdog->timeout);
 158        omap_wdt_reload(wdev); /* trigger loading of new timeout value */
 159        omap_wdt_enable(wdev);
 160
 161        mutex_unlock(&wdev->lock);
 162
 163        return 0;
 164}
 165
 166static int omap_wdt_stop(struct watchdog_device *wdog)
 167{
 168        struct omap_wdt_dev *wdev = to_omap_wdt_dev(wdog);
 169
 170        mutex_lock(&wdev->lock);
 171        omap_wdt_disable(wdev);
 172        pm_runtime_put_sync(wdev->dev);
 173        wdev->omap_wdt_users = false;
 174        mutex_unlock(&wdev->lock);
 175        return 0;
 176}
 177
 178static int omap_wdt_ping(struct watchdog_device *wdog)
 179{
 180        struct omap_wdt_dev *wdev = to_omap_wdt_dev(wdog);
 181
 182        mutex_lock(&wdev->lock);
 183        omap_wdt_reload(wdev);
 184        mutex_unlock(&wdev->lock);
 185
 186        return 0;
 187}
 188
 189static int omap_wdt_set_timeout(struct watchdog_device *wdog,
 190                                unsigned int timeout)
 191{
 192        struct omap_wdt_dev *wdev = to_omap_wdt_dev(wdog);
 193
 194        mutex_lock(&wdev->lock);
 195        omap_wdt_disable(wdev);
 196        omap_wdt_set_timer(wdev, timeout);
 197        omap_wdt_enable(wdev);
 198        omap_wdt_reload(wdev);
 199        wdog->timeout = timeout;
 200        mutex_unlock(&wdev->lock);
 201
 202        return 0;
 203}
 204
 205static unsigned int omap_wdt_get_timeleft(struct watchdog_device *wdog)
 206{
 207        struct omap_wdt_dev *wdev = to_omap_wdt_dev(wdog);
 208        void __iomem *base = wdev->base;
 209        u32 value;
 210
 211        value = readl_relaxed(base + OMAP_WATCHDOG_CRR);
 212        return GET_WCCR_SECS(value);
 213}
 214
 215static const struct watchdog_info omap_wdt_info = {
 216        .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 217        .identity = "OMAP Watchdog",
 218};
 219
 220static const struct watchdog_ops omap_wdt_ops = {
 221        .owner          = THIS_MODULE,
 222        .start          = omap_wdt_start,
 223        .stop           = omap_wdt_stop,
 224        .ping           = omap_wdt_ping,
 225        .set_timeout    = omap_wdt_set_timeout,
 226        .get_timeleft   = omap_wdt_get_timeleft,
 227};
 228
 229static int omap_wdt_probe(struct platform_device *pdev)
 230{
 231        struct omap_wd_timer_platform_data *pdata = dev_get_platdata(&pdev->dev);
 232        struct omap_wdt_dev *wdev;
 233        int ret;
 234
 235        wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
 236        if (!wdev)
 237                return -ENOMEM;
 238
 239        wdev->omap_wdt_users    = false;
 240        wdev->dev               = &pdev->dev;
 241        wdev->wdt_trgr_pattern  = 0x1234;
 242        mutex_init(&wdev->lock);
 243
 244        /* reserve static register mappings */
 245        wdev->base = devm_platform_ioremap_resource(pdev, 0);
 246        if (IS_ERR(wdev->base))
 247                return PTR_ERR(wdev->base);
 248
 249        wdev->wdog.info = &omap_wdt_info;
 250        wdev->wdog.ops = &omap_wdt_ops;
 251        wdev->wdog.min_timeout = TIMER_MARGIN_MIN;
 252        wdev->wdog.max_timeout = TIMER_MARGIN_MAX;
 253        wdev->wdog.timeout = TIMER_MARGIN_DEFAULT;
 254        wdev->wdog.parent = &pdev->dev;
 255
 256        watchdog_init_timeout(&wdev->wdog, timer_margin, &pdev->dev);
 257
 258        watchdog_set_nowayout(&wdev->wdog, nowayout);
 259
 260        platform_set_drvdata(pdev, wdev);
 261
 262        pm_runtime_enable(wdev->dev);
 263        pm_runtime_get_sync(wdev->dev);
 264
 265        if (pdata && pdata->read_reset_sources) {
 266                u32 rs = pdata->read_reset_sources();
 267                if (rs & (1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT))
 268                        wdev->wdog.bootstatus = WDIOF_CARDRESET;
 269        }
 270
 271        if (!early_enable)
 272                omap_wdt_disable(wdev);
 273
 274        ret = watchdog_register_device(&wdev->wdog);
 275        if (ret) {
 276                pm_runtime_put(wdev->dev);
 277                pm_runtime_disable(wdev->dev);
 278                return ret;
 279        }
 280
 281        pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec\n",
 282                readl_relaxed(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
 283                wdev->wdog.timeout);
 284
 285        if (early_enable)
 286                omap_wdt_start(&wdev->wdog);
 287
 288        pm_runtime_put(wdev->dev);
 289
 290        return 0;
 291}
 292
 293static void omap_wdt_shutdown(struct platform_device *pdev)
 294{
 295        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 296
 297        mutex_lock(&wdev->lock);
 298        if (wdev->omap_wdt_users) {
 299                omap_wdt_disable(wdev);
 300                pm_runtime_put_sync(wdev->dev);
 301        }
 302        mutex_unlock(&wdev->lock);
 303}
 304
 305static int omap_wdt_remove(struct platform_device *pdev)
 306{
 307        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 308
 309        pm_runtime_disable(wdev->dev);
 310        watchdog_unregister_device(&wdev->wdog);
 311
 312        return 0;
 313}
 314
 315#ifdef  CONFIG_PM
 316
 317/* REVISIT ... not clear this is the best way to handle system suspend; and
 318 * it's very inappropriate for selective device suspend (e.g. suspending this
 319 * through sysfs rather than by stopping the watchdog daemon).  Also, this
 320 * may not play well enough with NOWAYOUT...
 321 */
 322
 323static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
 324{
 325        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 326
 327        mutex_lock(&wdev->lock);
 328        if (wdev->omap_wdt_users) {
 329                omap_wdt_disable(wdev);
 330                pm_runtime_put_sync(wdev->dev);
 331        }
 332        mutex_unlock(&wdev->lock);
 333
 334        return 0;
 335}
 336
 337static int omap_wdt_resume(struct platform_device *pdev)
 338{
 339        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 340
 341        mutex_lock(&wdev->lock);
 342        if (wdev->omap_wdt_users) {
 343                pm_runtime_get_sync(wdev->dev);
 344                omap_wdt_enable(wdev);
 345                omap_wdt_reload(wdev);
 346        }
 347        mutex_unlock(&wdev->lock);
 348
 349        return 0;
 350}
 351
 352#else
 353#define omap_wdt_suspend        NULL
 354#define omap_wdt_resume         NULL
 355#endif
 356
 357static const struct of_device_id omap_wdt_of_match[] = {
 358        { .compatible = "ti,omap3-wdt", },
 359        {},
 360};
 361MODULE_DEVICE_TABLE(of, omap_wdt_of_match);
 362
 363static struct platform_driver omap_wdt_driver = {
 364        .probe          = omap_wdt_probe,
 365        .remove         = omap_wdt_remove,
 366        .shutdown       = omap_wdt_shutdown,
 367        .suspend        = omap_wdt_suspend,
 368        .resume         = omap_wdt_resume,
 369        .driver         = {
 370                .name   = "omap_wdt",
 371                .of_match_table = omap_wdt_of_match,
 372        },
 373};
 374
 375module_platform_driver(omap_wdt_driver);
 376
 377MODULE_AUTHOR("George G. Davis");
 378MODULE_LICENSE("GPL");
 379MODULE_ALIAS("platform:omap_wdt");
 380