linux/drivers/watchdog/armada_37xx_wdt.c
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   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Watchdog driver for Marvell Armada 37xx SoCs
   4 *
   5 * Author: Marek Beh\xC3\xBAn <kabel@kernel.org>
   6 */
   7
   8#include <linux/clk.h>
   9#include <linux/err.h>
  10#include <linux/interrupt.h>
  11#include <linux/io.h>
  12#include <linux/kernel.h>
  13#include <linux/mfd/syscon.h>
  14#include <linux/module.h>
  15#include <linux/moduleparam.h>
  16#include <linux/of.h>
  17#include <linux/of_device.h>
  18#include <linux/platform_device.h>
  19#include <linux/regmap.h>
  20#include <linux/types.h>
  21#include <linux/watchdog.h>
  22
  23/*
  24 * There are four counters that can be used for watchdog on Armada 37xx.
  25 * The addresses for counter control registers are register base plus ID*0x10,
  26 * where ID is 0, 1, 2 or 3.
  27 *
  28 * In this driver we use IDs 0 and 1. Counter ID 1 is used as watchdog counter,
  29 * while counter ID 0 is used to implement pinging the watchdog: counter ID 1 is
  30 * set to restart counting from initial value on counter ID 0 end count event.
  31 * Pinging is done by forcing immediate end count event on counter ID 0.
  32 * If only one counter was used, pinging would have to be implemented by
  33 * disabling and enabling the counter, leaving the system in a vulnerable state
  34 * for a (really) short period of time.
  35 *
  36 * Counters ID 2 and 3 are enabled by default even before U-Boot loads,
  37 * therefore this driver does not provide a way to use them, eg. by setting a
  38 * property in device tree.
  39 */
  40
  41#define CNTR_ID_RETRIGGER               0
  42#define CNTR_ID_WDOG                    1
  43
  44/* relative to cpu_misc */
  45#define WDT_TIMER_SELECT                0x64
  46#define WDT_TIMER_SELECT_MASK           0xf
  47#define WDT_TIMER_SELECT_VAL            BIT(CNTR_ID_WDOG)
  48
  49/* relative to reg */
  50#define CNTR_CTRL(id)                   ((id) * 0x10)
  51#define CNTR_CTRL_ENABLE                0x0001
  52#define CNTR_CTRL_ACTIVE                0x0002
  53#define CNTR_CTRL_MODE_MASK             0x000c
  54#define CNTR_CTRL_MODE_ONESHOT          0x0000
  55#define CNTR_CTRL_MODE_HWSIG            0x000c
  56#define CNTR_CTRL_TRIG_SRC_MASK         0x00f0
  57#define CNTR_CTRL_TRIG_SRC_PREV_CNTR    0x0050
  58#define CNTR_CTRL_PRESCALE_MASK         0xff00
  59#define CNTR_CTRL_PRESCALE_MIN          2
  60#define CNTR_CTRL_PRESCALE_SHIFT        8
  61
  62#define CNTR_COUNT_LOW(id)              (CNTR_CTRL(id) + 0x4)
  63#define CNTR_COUNT_HIGH(id)             (CNTR_CTRL(id) + 0x8)
  64
  65#define WATCHDOG_TIMEOUT                120
  66
  67static unsigned int timeout;
  68module_param(timeout, int, 0);
  69MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
  70
  71static bool nowayout = WATCHDOG_NOWAYOUT;
  72module_param(nowayout, bool, 0);
  73MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  74                           __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  75
  76struct armada_37xx_watchdog {
  77        struct watchdog_device wdt;
  78        struct regmap *cpu_misc;
  79        void __iomem *reg;
  80        u64 timeout; /* in clock ticks */
  81        unsigned long clk_rate;
  82        struct clk *clk;
  83};
  84
  85static u64 get_counter_value(struct armada_37xx_watchdog *dev, int id)
  86{
  87        u64 val;
  88
  89        /*
  90         * when low is read, high is latched into flip-flops so that it can be
  91         * read consistently without using software debouncing
  92         */
  93        val = readl(dev->reg + CNTR_COUNT_LOW(id));
  94        val |= ((u64)readl(dev->reg + CNTR_COUNT_HIGH(id))) << 32;
  95
  96        return val;
  97}
  98
  99static void set_counter_value(struct armada_37xx_watchdog *dev, int id, u64 val)
 100{
 101        writel(val & 0xffffffff, dev->reg + CNTR_COUNT_LOW(id));
 102        writel(val >> 32, dev->reg + CNTR_COUNT_HIGH(id));
 103}
 104
 105static void counter_enable(struct armada_37xx_watchdog *dev, int id)
 106{
 107        u32 reg;
 108
 109        reg = readl(dev->reg + CNTR_CTRL(id));
 110        reg |= CNTR_CTRL_ENABLE;
 111        writel(reg, dev->reg + CNTR_CTRL(id));
 112}
 113
 114static void counter_disable(struct armada_37xx_watchdog *dev, int id)
 115{
 116        u32 reg;
 117
 118        reg = readl(dev->reg + CNTR_CTRL(id));
 119        reg &= ~CNTR_CTRL_ENABLE;
 120        writel(reg, dev->reg + CNTR_CTRL(id));
 121}
 122
 123static void init_counter(struct armada_37xx_watchdog *dev, int id, u32 mode,
 124                         u32 trig_src)
 125{
 126        u32 reg;
 127
 128        reg = readl(dev->reg + CNTR_CTRL(id));
 129
 130        reg &= ~(CNTR_CTRL_MODE_MASK | CNTR_CTRL_PRESCALE_MASK |
 131                 CNTR_CTRL_TRIG_SRC_MASK);
 132
 133        /* set mode */
 134        reg |= mode & CNTR_CTRL_MODE_MASK;
 135
 136        /* set prescaler to the min value */
 137        reg |= CNTR_CTRL_PRESCALE_MIN << CNTR_CTRL_PRESCALE_SHIFT;
 138
 139        /* set trigger source */
 140        reg |= trig_src & CNTR_CTRL_TRIG_SRC_MASK;
 141
 142        writel(reg, dev->reg + CNTR_CTRL(id));
 143}
 144
 145static int armada_37xx_wdt_ping(struct watchdog_device *wdt)
 146{
 147        struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 148
 149        /* counter 1 is retriggered by forcing end count on counter 0 */
 150        counter_disable(dev, CNTR_ID_RETRIGGER);
 151        counter_enable(dev, CNTR_ID_RETRIGGER);
 152
 153        return 0;
 154}
 155
 156static unsigned int armada_37xx_wdt_get_timeleft(struct watchdog_device *wdt)
 157{
 158        struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 159        u64 res;
 160
 161        res = get_counter_value(dev, CNTR_ID_WDOG) * CNTR_CTRL_PRESCALE_MIN;
 162        do_div(res, dev->clk_rate);
 163
 164        return res;
 165}
 166
 167static int armada_37xx_wdt_set_timeout(struct watchdog_device *wdt,
 168                                       unsigned int timeout)
 169{
 170        struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 171
 172        wdt->timeout = timeout;
 173
 174        /*
 175         * Compute the timeout in clock rate. We use smallest possible
 176         * prescaler, which divides the clock rate by 2
 177         * (CNTR_CTRL_PRESCALE_MIN).
 178         */
 179        dev->timeout = (u64)dev->clk_rate * timeout;
 180        do_div(dev->timeout, CNTR_CTRL_PRESCALE_MIN);
 181
 182        return 0;
 183}
 184
 185static bool armada_37xx_wdt_is_running(struct armada_37xx_watchdog *dev)
 186{
 187        u32 reg;
 188
 189        regmap_read(dev->cpu_misc, WDT_TIMER_SELECT, &reg);
 190        if ((reg & WDT_TIMER_SELECT_MASK) != WDT_TIMER_SELECT_VAL)
 191                return false;
 192
 193        reg = readl(dev->reg + CNTR_CTRL(CNTR_ID_WDOG));
 194        return !!(reg & CNTR_CTRL_ACTIVE);
 195}
 196
 197static int armada_37xx_wdt_start(struct watchdog_device *wdt)
 198{
 199        struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 200
 201        /* select counter 1 as watchdog counter */
 202        regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, WDT_TIMER_SELECT_VAL);
 203
 204        /* init counter 0 as retrigger counter for counter 1 */
 205        init_counter(dev, CNTR_ID_RETRIGGER, CNTR_CTRL_MODE_ONESHOT, 0);
 206        set_counter_value(dev, CNTR_ID_RETRIGGER, 0);
 207
 208        /* init counter 1 to be retriggerable by counter 0 end count */
 209        init_counter(dev, CNTR_ID_WDOG, CNTR_CTRL_MODE_HWSIG,
 210                     CNTR_CTRL_TRIG_SRC_PREV_CNTR);
 211        set_counter_value(dev, CNTR_ID_WDOG, dev->timeout);
 212
 213        /* enable counter 1 */
 214        counter_enable(dev, CNTR_ID_WDOG);
 215
 216        /* start counter 1 by forcing immediate end count on counter 0 */
 217        counter_enable(dev, CNTR_ID_RETRIGGER);
 218
 219        return 0;
 220}
 221
 222static int armada_37xx_wdt_stop(struct watchdog_device *wdt)
 223{
 224        struct armada_37xx_watchdog *dev = watchdog_get_drvdata(wdt);
 225
 226        counter_disable(dev, CNTR_ID_WDOG);
 227        counter_disable(dev, CNTR_ID_RETRIGGER);
 228        regmap_write(dev->cpu_misc, WDT_TIMER_SELECT, 0);
 229
 230        return 0;
 231}
 232
 233static const struct watchdog_info armada_37xx_wdt_info = {
 234        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 235        .identity = "Armada 37xx Watchdog",
 236};
 237
 238static const struct watchdog_ops armada_37xx_wdt_ops = {
 239        .owner = THIS_MODULE,
 240        .start = armada_37xx_wdt_start,
 241        .stop = armada_37xx_wdt_stop,
 242        .ping = armada_37xx_wdt_ping,
 243        .set_timeout = armada_37xx_wdt_set_timeout,
 244        .get_timeleft = armada_37xx_wdt_get_timeleft,
 245};
 246
 247static void armada_clk_disable_unprepare(void *data)
 248{
 249        clk_disable_unprepare(data);
 250}
 251
 252static int armada_37xx_wdt_probe(struct platform_device *pdev)
 253{
 254        struct armada_37xx_watchdog *dev;
 255        struct resource *res;
 256        struct regmap *regmap;
 257        int ret;
 258
 259        dev = devm_kzalloc(&pdev->dev, sizeof(struct armada_37xx_watchdog),
 260                           GFP_KERNEL);
 261        if (!dev)
 262                return -ENOMEM;
 263
 264        dev->wdt.info = &armada_37xx_wdt_info;
 265        dev->wdt.ops = &armada_37xx_wdt_ops;
 266
 267        regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
 268                                                 "marvell,system-controller");
 269        if (IS_ERR(regmap))
 270                return PTR_ERR(regmap);
 271        dev->cpu_misc = regmap;
 272
 273        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 274        if (!res)
 275                return -ENODEV;
 276        dev->reg = devm_ioremap(&pdev->dev, res->start, resource_size(res));
 277
 278        /* init clock */
 279        dev->clk = devm_clk_get(&pdev->dev, NULL);
 280        if (IS_ERR(dev->clk))
 281                return PTR_ERR(dev->clk);
 282
 283        ret = clk_prepare_enable(dev->clk);
 284        if (ret)
 285                return ret;
 286        ret = devm_add_action_or_reset(&pdev->dev,
 287                                       armada_clk_disable_unprepare, dev->clk);
 288        if (ret)
 289                return ret;
 290
 291        dev->clk_rate = clk_get_rate(dev->clk);
 292        if (!dev->clk_rate)
 293                return -EINVAL;
 294
 295        /*
 296         * Since the timeout in seconds is given as 32 bit unsigned int, and
 297         * the counters hold 64 bit values, even after multiplication by clock
 298         * rate the counter can hold timeout of UINT_MAX seconds.
 299         */
 300        dev->wdt.min_timeout = 1;
 301        dev->wdt.max_timeout = UINT_MAX;
 302        dev->wdt.parent = &pdev->dev;
 303
 304        /* default value, possibly override by module parameter or dtb */
 305        dev->wdt.timeout = WATCHDOG_TIMEOUT;
 306        watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
 307
 308        platform_set_drvdata(pdev, &dev->wdt);
 309        watchdog_set_drvdata(&dev->wdt, dev);
 310
 311        armada_37xx_wdt_set_timeout(&dev->wdt, dev->wdt.timeout);
 312
 313        if (armada_37xx_wdt_is_running(dev))
 314                set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
 315
 316        watchdog_set_nowayout(&dev->wdt, nowayout);
 317        watchdog_stop_on_reboot(&dev->wdt);
 318        ret = devm_watchdog_register_device(&pdev->dev, &dev->wdt);
 319        if (ret)
 320                return ret;
 321
 322        dev_info(&pdev->dev, "Initial timeout %d sec%s\n",
 323                 dev->wdt.timeout, nowayout ? ", nowayout" : "");
 324
 325        return 0;
 326}
 327
 328static int __maybe_unused armada_37xx_wdt_suspend(struct device *dev)
 329{
 330        struct watchdog_device *wdt = dev_get_drvdata(dev);
 331
 332        return armada_37xx_wdt_stop(wdt);
 333}
 334
 335static int __maybe_unused armada_37xx_wdt_resume(struct device *dev)
 336{
 337        struct watchdog_device *wdt = dev_get_drvdata(dev);
 338
 339        if (watchdog_active(wdt))
 340                return armada_37xx_wdt_start(wdt);
 341
 342        return 0;
 343}
 344
 345static const struct dev_pm_ops armada_37xx_wdt_dev_pm_ops = {
 346        SET_SYSTEM_SLEEP_PM_OPS(armada_37xx_wdt_suspend,
 347                                armada_37xx_wdt_resume)
 348};
 349
 350#ifdef CONFIG_OF
 351static const struct of_device_id armada_37xx_wdt_match[] = {
 352        { .compatible = "marvell,armada-3700-wdt", },
 353        {},
 354};
 355MODULE_DEVICE_TABLE(of, armada_37xx_wdt_match);
 356#endif
 357
 358static struct platform_driver armada_37xx_wdt_driver = {
 359        .probe          = armada_37xx_wdt_probe,
 360        .driver         = {
 361                .name   = "armada_37xx_wdt",
 362                .of_match_table = of_match_ptr(armada_37xx_wdt_match),
 363                .pm = &armada_37xx_wdt_dev_pm_ops,
 364        },
 365};
 366
 367module_platform_driver(armada_37xx_wdt_driver);
 368
 369MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
 370MODULE_DESCRIPTION("Armada 37xx CPU Watchdog");
 371
 372MODULE_LICENSE("GPL v2");
 373MODULE_ALIAS("platform:armada_37xx_wdt");
 374