// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2010-2011 Picochip Ltd., Jamie Iles
 * https://www.picochip.com
 *
 * This file implements a driver for the Synopsys DesignWare watchdog device
 * in the many subsystems. The watchdog has 16 different timeout periods
 * and these are a function of the input clock frequency.
 *
 * The DesignWare watchdog cannot be stopped once it has been started so we
 * do not implement a stop function. The watchdog core will continue to send
 * heartbeat requests after the watchdog device has been closed.
 */

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/reset.h>
#include <linux/watchdog.h>

#define WDOG_CONTROL_REG_OFFSET             0x00
#define WDOG_CONTROL_REG_WDT_EN_MASK        0x01
#define WDOG_CONTROL_REG_RESP_MODE_MASK     0x02
#define WDOG_TIMEOUT_RANGE_REG_OFFSET       0x04
#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
#define WDOG_CURRENT_COUNT_REG_OFFSET       0x08
#define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
#define WDOG_COUNTER_RESTART_KICK_VALUE     0x76
#define WDOG_INTERRUPT_STATUS_REG_OFFSET    0x10
#define WDOG_INTERRUPT_CLEAR_REG_OFFSET     0x14
#define WDOG_COMP_PARAMS_5_REG_OFFSET       0xe4
#define WDOG_COMP_PARAMS_4_REG_OFFSET       0xe8
#define WDOG_COMP_PARAMS_3_REG_OFFSET       0xec
#define WDOG_COMP_PARAMS_2_REG_OFFSET       0xf0
#define WDOG_COMP_PARAMS_1_REG_OFFSET       0xf4
#define WDOG_COMP_PARAMS_1_USE_FIX_TOP      BIT(6)
#define WDOG_COMP_VERSION_REG_OFFSET        0xf8
#define WDOG_COMP_TYPE_REG_OFFSET           0xfc

/* There are sixteen TOPs (timeout periods) that can be set in the watchdog. */
#define DW_WDT_NUM_TOPS         16
#define DW_WDT_FIX_TOP(_idx)    (1U << (16 + _idx))

#define DW_WDT_DEFAULT_SECONDS  30

static const u32 dw_wdt_fix_tops[DW_WDT_NUM_TOPS] = {
        DW_WDT_FIX_TOP(0), DW_WDT_FIX_TOP(1), DW_WDT_FIX_TOP(2),
        DW_WDT_FIX_TOP(3), DW_WDT_FIX_TOP(4), DW_WDT_FIX_TOP(5),
        DW_WDT_FIX_TOP(6), DW_WDT_FIX_TOP(7), DW_WDT_FIX_TOP(8),
        DW_WDT_FIX_TOP(9), DW_WDT_FIX_TOP(10), DW_WDT_FIX_TOP(11),
        DW_WDT_FIX_TOP(12), DW_WDT_FIX_TOP(13), DW_WDT_FIX_TOP(14),
        DW_WDT_FIX_TOP(15)
};

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
                 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

enum dw_wdt_rmod {
        DW_WDT_RMOD_RESET = 1,
        DW_WDT_RMOD_IRQ = 2
};

struct dw_wdt_timeout {
        u32 top_val;
        unsigned int sec;
        unsigned int msec;
};

struct dw_wdt {
        void __iomem            *regs;
        struct clk              *clk;
        struct clk              *pclk;
        unsigned long           rate;
        enum dw_wdt_rmod        rmod;
        struct dw_wdt_timeout   timeouts[DW_WDT_NUM_TOPS];
        struct watchdog_device  wdd;
        struct reset_control    *rst;
        /* Save/restore */
        u32                     control;
        u32                     timeout;

#ifdef CONFIG_DEBUG_FS
        struct dentry           *dbgfs_dir;
#endif
};

#define to_dw_wdt(wdd)  container_of(wdd, struct dw_wdt, wdd)

static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
{
        return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
                WDOG_CONTROL_REG_WDT_EN_MASK;
}

static void dw_wdt_update_mode(struct dw_wdt *dw_wdt, enum dw_wdt_rmod rmod)
{
        u32 val;

        val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
        if (rmod == DW_WDT_RMOD_IRQ)
                val |= WDOG_CONTROL_REG_RESP_MODE_MASK;
        else
                val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
        writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

        dw_wdt->rmod = rmod;
}

static unsigned int dw_wdt_find_best_top(struct dw_wdt *dw_wdt,
                                         unsigned int timeout, u32 *top_val)
{
        int idx;

        /*
         * Find a TOP with timeout greater or equal to the requested number.
         * Note we'll select a TOP with maximum timeout if the requested
         * timeout couldn't be reached.
         */
        for (idx = 0; idx < DW_WDT_NUM_TOPS; ++idx) {
                if (dw_wdt->timeouts[idx].sec >= timeout)
                        break;
        }

        if (idx == DW_WDT_NUM_TOPS)
                --idx;

        *top_val = dw_wdt->timeouts[idx].top_val;

        return dw_wdt->timeouts[idx].sec;
}

static unsigned int dw_wdt_get_min_timeout(struct dw_wdt *dw_wdt)
{
        int idx;

        /*
         * We'll find a timeout greater or equal to one second anyway because
         * the driver probe would have failed if there was none.
         */
        for (idx = 0; idx < DW_WDT_NUM_TOPS; ++idx) {
                if (dw_wdt->timeouts[idx].sec)
                        break;
        }

        return dw_wdt->timeouts[idx].sec;
}

static unsigned int dw_wdt_get_max_timeout_ms(struct dw_wdt *dw_wdt)
{
        struct dw_wdt_timeout *timeout = &dw_wdt->timeouts[DW_WDT_NUM_TOPS - 1];
        u64 msec;

        msec = (u64)timeout->sec * MSEC_PER_SEC + timeout->msec;

        return msec < UINT_MAX ? msec : UINT_MAX;
}

static unsigned int dw_wdt_get_timeout(struct dw_wdt *dw_wdt)
{
        int top_val = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
        int idx;

        for (idx = 0; idx < DW_WDT_NUM_TOPS; ++idx) {
                if (dw_wdt->timeouts[idx].top_val == top_val)
                        break;
        }

        /*
         * In IRQ mode due to the two stages counter, the actual timeout is
         * twice greater than the TOP setting.
         */
        return dw_wdt->timeouts[idx].sec * dw_wdt->rmod;
}

static int dw_wdt_ping(struct watchdog_device *wdd)
{
        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

        writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
               WDOG_COUNTER_RESTART_REG_OFFSET);

        return 0;
}

static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
{
        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
        unsigned int timeout;
        u32 top_val;

        /*
         * Note IRQ mode being enabled means having a non-zero pre-timeout
         * setup. In this case we try to find a TOP as close to the half of the
         * requested timeout as possible since DW Watchdog IRQ mode is designed
         * in two stages way - first timeout rises the pre-timeout interrupt,
         * second timeout performs the system reset. So basically the effective
         * watchdog-caused reset happens after two watchdog TOPs elapsed.
         */
        timeout = dw_wdt_find_best_top(dw_wdt, DIV_ROUND_UP(top_s, dw_wdt->rmod),
                                       &top_val);
        if (dw_wdt->rmod == DW_WDT_RMOD_IRQ)
                wdd->pretimeout = timeout;
        else
                wdd->pretimeout = 0;

        /*
         * Set the new value in the watchdog.  Some versions of dw_wdt
         * have TOPINIT in the TIMEOUT_RANGE register (as per
         * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
         * effectively get a pat of the watchdog right here.
         */
        writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
               dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

        /* Kick new TOP value into the watchdog counter if activated. */
        if (watchdog_active(wdd))
                dw_wdt_ping(wdd);

        /*
         * In case users set bigger timeout value than HW can support,
         * kernel(watchdog_dev.c) helps to feed watchdog before
         * wdd->max_hw_heartbeat_ms
         */
        if (top_s * 1000 <= wdd->max_hw_heartbeat_ms)
                wdd->timeout = timeout * dw_wdt->rmod;
        else
                wdd->timeout = top_s;

        return 0;
}

static int dw_wdt_set_pretimeout(struct watchdog_device *wdd, unsigned int req)
{
        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

        /*
         * We ignore actual value of the timeout passed from user-space
         * using it as a flag whether the pretimeout functionality is intended
         * to be activated.
         */
        dw_wdt_update_mode(dw_wdt, req ? DW_WDT_RMOD_IRQ : DW_WDT_RMOD_RESET);
        dw_wdt_set_timeout(wdd, wdd->timeout);

        return 0;
}

static void dw_wdt_arm_system_reset(struct dw_wdt *dw_wdt)
{
        u32 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

        /* Disable/enable interrupt mode depending on the RMOD flag. */
        if (dw_wdt->rmod == DW_WDT_RMOD_IRQ)
                val |= WDOG_CONTROL_REG_RESP_MODE_MASK;
        else
                val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
        /* Enable watchdog. */
        val |= WDOG_CONTROL_REG_WDT_EN_MASK;
        writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
}

static int dw_wdt_start(struct watchdog_device *wdd)
{
        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

        dw_wdt_set_timeout(wdd, wdd->timeout);
        dw_wdt_ping(&dw_wdt->wdd);
        dw_wdt_arm_system_reset(dw_wdt);

        return 0;
}

static int dw_wdt_stop(struct watchdog_device *wdd)
{
        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

        if (!dw_wdt->rst) {
                set_bit(WDOG_HW_RUNNING, &wdd->status);
                return 0;
        }

        reset_control_assert(dw_wdt->rst);
        reset_control_deassert(dw_wdt->rst);

        return 0;
}

static int dw_wdt_restart(struct watchdog_device *wdd,
                          unsigned long action, void *data)
{
        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

        writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
        dw_wdt_update_mode(dw_wdt, DW_WDT_RMOD_RESET);
        if (dw_wdt_is_enabled(dw_wdt))
                writel(WDOG_COUNTER_RESTART_KICK_VALUE,
                       dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
        else
                dw_wdt_arm_system_reset(dw_wdt);

        /* wait for reset to assert... */
        mdelay(500);

        return 0;
}

static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
{
        struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
        unsigned int sec;
        u32 val;

        val = readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET);
        sec = val / dw_wdt->rate;

        if (dw_wdt->rmod == DW_WDT_RMOD_IRQ) {
                val = readl(dw_wdt->regs + WDOG_INTERRUPT_STATUS_REG_OFFSET);
                if (!val)
                        sec += wdd->pretimeout;
        }

        return sec;
}

static const struct watchdog_info dw_wdt_ident = {
        .options        = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
                          WDIOF_MAGICCLOSE,
        .identity       = "Synopsys DesignWare Watchdog",
};

static const struct watchdog_info dw_wdt_pt_ident = {
        .options        = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
                          WDIOF_PRETIMEOUT | WDIOF_MAGICCLOSE,
        .identity       = "Synopsys DesignWare Watchdog",
};

static const struct watchdog_ops dw_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = dw_wdt_start,
        .stop           = dw_wdt_stop,
        .ping           = dw_wdt_ping,
        .set_timeout    = dw_wdt_set_timeout,
        .set_pretimeout = dw_wdt_set_pretimeout,
        .get_timeleft   = dw_wdt_get_timeleft,
        .restart        = dw_wdt_restart,
};

static irqreturn_t dw_wdt_irq(int irq, void *devid)
{
        struct dw_wdt *dw_wdt = devid;
        u32 val;

        /*
         * We don't clear the IRQ status. It's supposed to be done by the
         * following ping operations.
         */
        val = readl(dw_wdt->regs + WDOG_INTERRUPT_STATUS_REG_OFFSET);
        if (!val)
                return IRQ_NONE;

        watchdog_notify_pretimeout(&dw_wdt->wdd);

        return IRQ_HANDLED;
}

static int dw_wdt_suspend(struct device *dev)
{
        struct dw_wdt *dw_wdt = dev_get_drvdata(dev);

        dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
        dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

        clk_disable_unprepare(dw_wdt->pclk);
        clk_disable_unprepare(dw_wdt->clk);

        return 0;
}

static int dw_wdt_resume(struct device *dev)
{
        struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
        int err = clk_prepare_enable(dw_wdt->clk);

        if (err)
                return err;

        err = clk_prepare_enable(dw_wdt->pclk);
        if (err) {
                clk_disable_unprepare(dw_wdt->clk);
                return err;
        }

        writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
        writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

        dw_wdt_ping(&dw_wdt->wdd);

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);

/*
 * In case if DW WDT IP core is synthesized with fixed TOP feature disabled the
 * TOPs array can be arbitrary ordered with nearly any sixteen uint numbers
 * depending on the system engineer imagination. The next method handles the
 * passed TOPs array to pre-calculate the effective timeouts and to sort the
 * TOP items out in the ascending order with respect to the timeouts.
 */

static void dw_wdt_handle_tops(struct dw_wdt *dw_wdt, const u32 *tops)
{
        struct dw_wdt_timeout tout, *dst;
        int val, tidx;
        u64 msec;

        /*
         * We walk over the passed TOPs array and calculate corresponding
         * timeouts in seconds and milliseconds. The milliseconds granularity
         * is needed to distinguish the TOPs with very close timeouts and to
         * set the watchdog max heartbeat setting further.
         */
        for (val = 0; val < DW_WDT_NUM_TOPS; ++val) {
                tout.top_val = val;
                tout.sec = tops[val] / dw_wdt->rate;
                msec = (u64)tops[val] * MSEC_PER_SEC;
                do_div(msec, dw_wdt->rate);
                tout.msec = msec - ((u64)tout.sec * MSEC_PER_SEC);

                /*
                 * Find a suitable place for the current TOP in the timeouts
                 * array so that the list is remained in the ascending order.
                 */
                for (tidx = 0; tidx < val; ++tidx) {
                        dst = &dw_wdt->timeouts[tidx];
                        if (tout.sec > dst->sec || (tout.sec == dst->sec &&
                            tout.msec >= dst->msec))
                                continue;
                        else
                                swap(*dst, tout);
                }

                dw_wdt->timeouts[val] = tout;
        }
}

static int dw_wdt_init_timeouts(struct dw_wdt *dw_wdt, struct device *dev)
{
        u32 data, of_tops[DW_WDT_NUM_TOPS];
        const u32 *tops;
        int ret;

        /*
         * Retrieve custom or fixed counter values depending on the
         * WDT_USE_FIX_TOP flag found in the component specific parameters
         * #1 register.
         */
        data = readl(dw_wdt->regs + WDOG_COMP_PARAMS_1_REG_OFFSET);
        if (data & WDOG_COMP_PARAMS_1_USE_FIX_TOP) {
                tops = dw_wdt_fix_tops;
        } else {
                ret = of_property_read_variable_u32_array(dev_of_node(dev),
                        "snps,watchdog-tops", of_tops, DW_WDT_NUM_TOPS,
                        DW_WDT_NUM_TOPS);
                if (ret < 0) {
                        dev_warn(dev, "No valid TOPs array specified\n");
                        tops = dw_wdt_fix_tops;
                } else {
                        tops = of_tops;
                }
        }

        /* Convert the specified TOPs into an array of watchdog timeouts. */
        dw_wdt_handle_tops(dw_wdt, tops);
        if (!dw_wdt->timeouts[DW_WDT_NUM_TOPS - 1].sec) {
                dev_err(dev, "No any valid TOP detected\n");
                return -EINVAL;
        }

        return 0;
}

#ifdef CONFIG_DEBUG_FS

#define DW_WDT_DBGFS_REG(_name, _off) \
{                                     \
        .name = _name,                \
        .offset = _off                \
}

static const struct debugfs_reg32 dw_wdt_dbgfs_regs[] = {
        DW_WDT_DBGFS_REG("cr", WDOG_CONTROL_REG_OFFSET),
        DW_WDT_DBGFS_REG("torr", WDOG_TIMEOUT_RANGE_REG_OFFSET),
        DW_WDT_DBGFS_REG("ccvr", WDOG_CURRENT_COUNT_REG_OFFSET),
        DW_WDT_DBGFS_REG("crr", WDOG_COUNTER_RESTART_REG_OFFSET),
        DW_WDT_DBGFS_REG("stat", WDOG_INTERRUPT_STATUS_REG_OFFSET),
        DW_WDT_DBGFS_REG("param5", WDOG_COMP_PARAMS_5_REG_OFFSET),
        DW_WDT_DBGFS_REG("param4", WDOG_COMP_PARAMS_4_REG_OFFSET),
        DW_WDT_DBGFS_REG("param3", WDOG_COMP_PARAMS_3_REG_OFFSET),
        DW_WDT_DBGFS_REG("param2", WDOG_COMP_PARAMS_2_REG_OFFSET),
        DW_WDT_DBGFS_REG("param1", WDOG_COMP_PARAMS_1_REG_OFFSET),
        DW_WDT_DBGFS_REG("version", WDOG_COMP_VERSION_REG_OFFSET),
        DW_WDT_DBGFS_REG("type", WDOG_COMP_TYPE_REG_OFFSET)
};

static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt)
{
        struct device *dev = dw_wdt->wdd.parent;
        struct debugfs_regset32 *regset;

        regset = devm_kzalloc(dev, sizeof(*regset), GFP_KERNEL);
        if (!regset)
                return;

        regset->regs = dw_wdt_dbgfs_regs;
        regset->nregs = ARRAY_SIZE(dw_wdt_dbgfs_regs);
        regset->base = dw_wdt->regs;

        dw_wdt->dbgfs_dir = debugfs_create_dir(dev_name(dev), NULL);

        debugfs_create_regset32("registers", 0444, dw_wdt->dbgfs_dir, regset);
}

static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt)
{
        debugfs_remove_recursive(dw_wdt->dbgfs_dir);
}

#else /* !CONFIG_DEBUG_FS */

static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt) {}
static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt) {}

#endif /* !CONFIG_DEBUG_FS */

static int dw_wdt_drv_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct watchdog_device *wdd;
        struct dw_wdt *dw_wdt;
        int ret;

        dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
        if (!dw_wdt)
                return -ENOMEM;

        dw_wdt->regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(dw_wdt->regs))
                return PTR_ERR(dw_wdt->regs);

        /*
         * Try to request the watchdog dedicated timer clock source. It must
         * be supplied if asynchronous mode is enabled. Otherwise fallback
         * to the common timer/bus clocks configuration, in which the very
         * first found clock supply both timer and APB signals.
         */
        dw_wdt->clk = devm_clk_get_enabled(dev, "tclk");
        if (IS_ERR(dw_wdt->clk)) {
                dw_wdt->clk = devm_clk_get_enabled(dev, NULL);
                if (IS_ERR(dw_wdt->clk))
                        return PTR_ERR(dw_wdt->clk);
        }

        dw_wdt->rate = clk_get_rate(dw_wdt->clk);
        if (dw_wdt->rate == 0)
                return -EINVAL;

        /*
         * Request APB clock if device is configured with async clocks mode.
         * In this case both tclk and pclk clocks are supposed to be specified.
         * Alas we can't know for sure whether async mode was really activated,
         * so the pclk phandle reference is left optional. If it couldn't be
         * found we consider the device configured in synchronous clocks mode.
         */
        dw_wdt->pclk = devm_clk_get_optional_enabled(dev, "pclk");
        if (IS_ERR(dw_wdt->pclk))
                return PTR_ERR(dw_wdt->pclk);

        dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
        if (IS_ERR(dw_wdt->rst))
                return PTR_ERR(dw_wdt->rst);

        /* Enable normal reset without pre-timeout by default. */
        dw_wdt_update_mode(dw_wdt, DW_WDT_RMOD_RESET);

        /*
         * Pre-timeout IRQ is optional, since some hardware may lack support
         * of it. Note we must request rising-edge IRQ, since the lane is left
         * pending either until the next watchdog kick event or up to the
         * system reset.
         */
        ret = platform_get_irq_optional(pdev, 0);
        if (ret > 0) {
                ret = devm_request_irq(dev, ret, dw_wdt_irq,
                                       IRQF_SHARED | IRQF_TRIGGER_RISING,
                                       pdev->name, dw_wdt);
                if (ret)
                        return ret;

                dw_wdt->wdd.info = &dw_wdt_pt_ident;
        } else {
                if (ret == -EPROBE_DEFER)
                        return ret;

                dw_wdt->wdd.info = &dw_wdt_ident;
        }

        reset_control_deassert(dw_wdt->rst);

        ret = dw_wdt_init_timeouts(dw_wdt, dev);
        if (ret)
                goto out_assert_rst;

        wdd = &dw_wdt->wdd;
        wdd->ops = &dw_wdt_ops;
        wdd->min_timeout = dw_wdt_get_min_timeout(dw_wdt);
        wdd->max_hw_heartbeat_ms = dw_wdt_get_max_timeout_ms(dw_wdt);
        wdd->parent = dev;

        watchdog_set_drvdata(wdd, dw_wdt);
        watchdog_set_nowayout(wdd, nowayout);
        watchdog_init_timeout(wdd, 0, dev);

        /*
         * If the watchdog is already running, use its already configured
         * timeout. Otherwise use the default or the value provided through
         * devicetree.
         */
        if (dw_wdt_is_enabled(dw_wdt)) {
                wdd->timeout = dw_wdt_get_timeout(dw_wdt);
                set_bit(WDOG_HW_RUNNING, &wdd->status);
        } else {
                wdd->timeout = DW_WDT_DEFAULT_SECONDS;
                watchdog_init_timeout(wdd, 0, dev);
                /* Limit timeout value to hardware constraints. */
                dw_wdt_set_timeout(wdd, wdd->timeout);
        }

        platform_set_drvdata(pdev, dw_wdt);

        watchdog_set_restart_priority(wdd, 128);
        watchdog_stop_on_reboot(wdd);

        ret = watchdog_register_device(wdd);
        if (ret)
                goto out_assert_rst;

        dw_wdt_dbgfs_init(dw_wdt);

        return 0;

out_assert_rst:
        reset_control_assert(dw_wdt->rst);
        return ret;
}

static void dw_wdt_drv_remove(struct platform_device *pdev)
{
        struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);

        dw_wdt_dbgfs_clear(dw_wdt);

        watchdog_unregister_device(&dw_wdt->wdd);
        reset_control_assert(dw_wdt->rst);
}

#ifdef CONFIG_OF
static const struct of_device_id dw_wdt_of_match[] = {
        { .compatible = "snps,dw-wdt", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
#endif

static struct platform_driver dw_wdt_driver = {
        .probe          = dw_wdt_drv_probe,
        .remove         = dw_wdt_drv_remove,
        .driver         = {
                .name   = "dw_wdt",
                .of_match_table = of_match_ptr(dw_wdt_of_match),
                .pm     = pm_sleep_ptr(&dw_wdt_pm_ops),
        },
};

module_platform_driver(dw_wdt_driver);

MODULE_AUTHOR("Jamie Iles");
MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
MODULE_LICENSE("GPL");