linux/drivers/watchdog/sp805_wdt.c
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   1/*
   2 * drivers/char/watchdog/sp805-wdt.c
   3 *
   4 * Watchdog driver for ARM SP805 watchdog module
   5 *
   6 * Copyright (C) 2010 ST Microelectronics
   7 * Viresh Kumar <vireshk@kernel.org>
   8 *
   9 * This file is licensed under the terms of the GNU General Public
  10 * License version 2 or later. This program is licensed "as is" without any
  11 * warranty of any kind, whether express or implied.
  12 */
  13
  14#include <linux/device.h>
  15#include <linux/resource.h>
  16#include <linux/amba/bus.h>
  17#include <linux/bitops.h>
  18#include <linux/clk.h>
  19#include <linux/io.h>
  20#include <linux/ioport.h>
  21#include <linux/kernel.h>
  22#include <linux/math64.h>
  23#include <linux/module.h>
  24#include <linux/moduleparam.h>
  25#include <linux/pm.h>
  26#include <linux/property.h>
  27#include <linux/slab.h>
  28#include <linux/spinlock.h>
  29#include <linux/types.h>
  30#include <linux/watchdog.h>
  31
  32/* default timeout in seconds */
  33#define DEFAULT_TIMEOUT         60
  34
  35#define MODULE_NAME             "sp805-wdt"
  36
  37/* watchdog register offsets and masks */
  38#define WDTLOAD                 0x000
  39        #define LOAD_MIN        0x00000001
  40        #define LOAD_MAX        0xFFFFFFFF
  41#define WDTVALUE                0x004
  42#define WDTCONTROL              0x008
  43        /* control register masks */
  44        #define INT_ENABLE      (1 << 0)
  45        #define RESET_ENABLE    (1 << 1)
  46        #define ENABLE_MASK     (INT_ENABLE | RESET_ENABLE)
  47#define WDTINTCLR               0x00C
  48#define WDTRIS                  0x010
  49#define WDTMIS                  0x014
  50        #define INT_MASK        (1 << 0)
  51#define WDTLOCK                 0xC00
  52        #define UNLOCK          0x1ACCE551
  53        #define LOCK            0x00000001
  54
  55/**
  56 * struct sp805_wdt: sp805 wdt device structure
  57 * @wdd: instance of struct watchdog_device
  58 * @lock: spin lock protecting dev structure and io access
  59 * @base: base address of wdt
  60 * @clk: (optional) clock structure of wdt
  61 * @rate: (optional) clock rate when provided via properties
  62 * @adev: amba device structure of wdt
  63 * @status: current status of wdt
  64 * @load_val: load value to be set for current timeout
  65 */
  66struct sp805_wdt {
  67        struct watchdog_device          wdd;
  68        spinlock_t                      lock;
  69        void __iomem                    *base;
  70        struct clk                      *clk;
  71        u64                             rate;
  72        struct amba_device              *adev;
  73        unsigned int                    load_val;
  74};
  75
  76static bool nowayout = WATCHDOG_NOWAYOUT;
  77module_param(nowayout, bool, 0);
  78MODULE_PARM_DESC(nowayout,
  79                "Set to 1 to keep watchdog running after device release");
  80
  81/* returns true if wdt is running; otherwise returns false */
  82static bool wdt_is_running(struct watchdog_device *wdd)
  83{
  84        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
  85        u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
  86
  87        return (wdtcontrol & ENABLE_MASK) == ENABLE_MASK;
  88}
  89
  90/* This routine finds load value that will reset system in required timout */
  91static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
  92{
  93        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
  94        u64 load, rate;
  95
  96        rate = wdt->rate;
  97
  98        /*
  99         * sp805 runs counter with given value twice, after the end of first
 100         * counter it gives an interrupt and then starts counter again. If
 101         * interrupt already occurred then it resets the system. This is why
 102         * load is half of what should be required.
 103         */
 104        load = div_u64(rate, 2) * timeout - 1;
 105
 106        load = (load > LOAD_MAX) ? LOAD_MAX : load;
 107        load = (load < LOAD_MIN) ? LOAD_MIN : load;
 108
 109        spin_lock(&wdt->lock);
 110        wdt->load_val = load;
 111        /* roundup timeout to closest positive integer value */
 112        wdd->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
 113        spin_unlock(&wdt->lock);
 114
 115        return 0;
 116}
 117
 118/* returns number of seconds left for reset to occur */
 119static unsigned int wdt_timeleft(struct watchdog_device *wdd)
 120{
 121        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 122        u64 load;
 123
 124        spin_lock(&wdt->lock);
 125        load = readl_relaxed(wdt->base + WDTVALUE);
 126
 127        /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
 128        if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
 129                load += wdt->load_val + 1;
 130        spin_unlock(&wdt->lock);
 131
 132        return div_u64(load, wdt->rate);
 133}
 134
 135static int
 136wdt_restart(struct watchdog_device *wdd, unsigned long mode, void *cmd)
 137{
 138        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 139
 140        writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 141        writel_relaxed(0, wdt->base + WDTCONTROL);
 142        writel_relaxed(0, wdt->base + WDTLOAD);
 143        writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
 144
 145        /* Flush posted writes. */
 146        readl_relaxed(wdt->base + WDTLOCK);
 147
 148        return 0;
 149}
 150
 151static int wdt_config(struct watchdog_device *wdd, bool ping)
 152{
 153        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 154        int ret;
 155
 156        if (!ping) {
 157
 158                ret = clk_prepare_enable(wdt->clk);
 159                if (ret) {
 160                        dev_err(&wdt->adev->dev, "clock enable fail");
 161                        return ret;
 162                }
 163        }
 164
 165        spin_lock(&wdt->lock);
 166
 167        writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 168        writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
 169        writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
 170
 171        if (!ping)
 172                writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
 173                                WDTCONTROL);
 174
 175        writel_relaxed(LOCK, wdt->base + WDTLOCK);
 176
 177        /* Flush posted writes. */
 178        readl_relaxed(wdt->base + WDTLOCK);
 179        spin_unlock(&wdt->lock);
 180
 181        return 0;
 182}
 183
 184static int wdt_ping(struct watchdog_device *wdd)
 185{
 186        return wdt_config(wdd, true);
 187}
 188
 189/* enables watchdog timers reset */
 190static int wdt_enable(struct watchdog_device *wdd)
 191{
 192        return wdt_config(wdd, false);
 193}
 194
 195/* disables watchdog timers reset */
 196static int wdt_disable(struct watchdog_device *wdd)
 197{
 198        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 199
 200        spin_lock(&wdt->lock);
 201
 202        writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 203        writel_relaxed(0, wdt->base + WDTCONTROL);
 204        writel_relaxed(LOCK, wdt->base + WDTLOCK);
 205
 206        /* Flush posted writes. */
 207        readl_relaxed(wdt->base + WDTLOCK);
 208        spin_unlock(&wdt->lock);
 209
 210        clk_disable_unprepare(wdt->clk);
 211
 212        return 0;
 213}
 214
 215static const struct watchdog_info wdt_info = {
 216        .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 217        .identity = MODULE_NAME,
 218};
 219
 220static const struct watchdog_ops wdt_ops = {
 221        .owner          = THIS_MODULE,
 222        .start          = wdt_enable,
 223        .stop           = wdt_disable,
 224        .ping           = wdt_ping,
 225        .set_timeout    = wdt_setload,
 226        .get_timeleft   = wdt_timeleft,
 227        .restart        = wdt_restart,
 228};
 229
 230static int
 231sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
 232{
 233        struct sp805_wdt *wdt;
 234        u64 rate = 0;
 235        int ret = 0;
 236
 237        wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
 238        if (!wdt) {
 239                ret = -ENOMEM;
 240                goto err;
 241        }
 242
 243        wdt->base = devm_ioremap_resource(&adev->dev, &adev->res);
 244        if (IS_ERR(wdt->base))
 245                return PTR_ERR(wdt->base);
 246
 247        /*
 248         * When driver probe with ACPI device, clock devices
 249         * are not available, so watchdog rate get from
 250         * clock-frequency property given in _DSD object.
 251         */
 252        device_property_read_u64(&adev->dev, "clock-frequency", &rate);
 253
 254        wdt->clk = devm_clk_get_optional(&adev->dev, NULL);
 255        if (IS_ERR(wdt->clk))
 256                return dev_err_probe(&adev->dev, PTR_ERR(wdt->clk), "Clock not found\n");
 257
 258        wdt->rate = clk_get_rate(wdt->clk);
 259        if (!wdt->rate)
 260                wdt->rate = rate;
 261        if (!wdt->rate) {
 262                dev_err(&adev->dev, "no clock-frequency property\n");
 263                return -ENODEV;
 264        }
 265
 266        wdt->adev = adev;
 267        wdt->wdd.info = &wdt_info;
 268        wdt->wdd.ops = &wdt_ops;
 269        wdt->wdd.parent = &adev->dev;
 270
 271        spin_lock_init(&wdt->lock);
 272        watchdog_set_nowayout(&wdt->wdd, nowayout);
 273        watchdog_set_drvdata(&wdt->wdd, wdt);
 274        watchdog_set_restart_priority(&wdt->wdd, 128);
 275        watchdog_stop_on_unregister(&wdt->wdd);
 276
 277        /*
 278         * If 'timeout-sec' devicetree property is specified, use that.
 279         * Otherwise, use DEFAULT_TIMEOUT
 280         */
 281        wdt->wdd.timeout = DEFAULT_TIMEOUT;
 282        watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
 283        wdt_setload(&wdt->wdd, wdt->wdd.timeout);
 284
 285        /*
 286         * If HW is already running, enable/reset the wdt and set the running
 287         * bit to tell the wdt subsystem
 288         */
 289        if (wdt_is_running(&wdt->wdd)) {
 290                wdt_enable(&wdt->wdd);
 291                set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
 292        }
 293
 294        watchdog_stop_on_reboot(&wdt->wdd);
 295        ret = watchdog_register_device(&wdt->wdd);
 296        if (ret)
 297                goto err;
 298        amba_set_drvdata(adev, wdt);
 299
 300        dev_info(&adev->dev, "registration successful\n");
 301        return 0;
 302
 303err:
 304        dev_err(&adev->dev, "Probe Failed!!!\n");
 305        return ret;
 306}
 307
 308static void sp805_wdt_remove(struct amba_device *adev)
 309{
 310        struct sp805_wdt *wdt = amba_get_drvdata(adev);
 311
 312        watchdog_unregister_device(&wdt->wdd);
 313        watchdog_set_drvdata(&wdt->wdd, NULL);
 314}
 315
 316static int __maybe_unused sp805_wdt_suspend(struct device *dev)
 317{
 318        struct sp805_wdt *wdt = dev_get_drvdata(dev);
 319
 320        if (watchdog_active(&wdt->wdd))
 321                return wdt_disable(&wdt->wdd);
 322
 323        return 0;
 324}
 325
 326static int __maybe_unused sp805_wdt_resume(struct device *dev)
 327{
 328        struct sp805_wdt *wdt = dev_get_drvdata(dev);
 329
 330        if (watchdog_active(&wdt->wdd))
 331                return wdt_enable(&wdt->wdd);
 332
 333        return 0;
 334}
 335
 336static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
 337                sp805_wdt_resume);
 338
 339static const struct amba_id sp805_wdt_ids[] = {
 340        {
 341                .id     = 0x00141805,
 342                .mask   = 0x00ffffff,
 343        },
 344        { 0, 0 },
 345};
 346
 347MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
 348
 349static struct amba_driver sp805_wdt_driver = {
 350        .drv = {
 351                .name   = MODULE_NAME,
 352                .pm     = &sp805_wdt_dev_pm_ops,
 353        },
 354        .id_table       = sp805_wdt_ids,
 355        .probe          = sp805_wdt_probe,
 356        .remove = sp805_wdt_remove,
 357};
 358
 359module_amba_driver(sp805_wdt_driver);
 360
 361MODULE_AUTHOR("Viresh Kumar <vireshk@kernel.org>");
 362MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
 363MODULE_LICENSE("GPL");
 364