[PATCH v5 2/3] drivers: watchdog: Add StarFive Watchdog driver

[Xingyu Wu]

Add watchdog driver for the StarFive JH7100 and JH7110 SoC.

Signed-off-by: Xingyu Wu <xingyu.wu@xxxxxxxxxxxxxxxx>
---
 MAINTAINERS                     |   7 +
 drivers/watchdog/Kconfig        |  11 +
 drivers/watchdog/Makefile       |   3 +
 drivers/watchdog/starfive-wdt.c | 606 ++++++++++++++++++++++++++++++++
 4 files changed, 627 insertions(+)
 create mode 100644 drivers/watchdog/starfive-wdt.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 8d5bc223f305..721d0e4e8a0d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19962,6 +19962,13 @@ S:	Supported
 F:	Documentation/devicetree/bindings/rng/starfive*
 F:	drivers/char/hw_random/jh7110-trng.c
 
+STARFIVE WATCHDOG DRIVER
+M:	Xingyu Wu <xingyu.wu@xxxxxxxxxxxxxxxx>
+M:	Samin Guo <samin.guo@xxxxxxxxxxxxxxxx>
+S:	Supported
+F:	Documentation/devicetree/bindings/watchdog/starfive*
+F:	drivers/watchdog/starfive-wdt.c
+
 STATIC BRANCH/CALL
 M:	Peter Zijlstra <peterz@xxxxxxxxxxxxx>
 M:	Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index f0872970daf9..f22138709bf5 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1999,6 +1999,17 @@ config WATCHDOG_RTAS
 	  To compile this driver as a module, choose M here. The module
 	  will be called wdrtas.
 
+# RISC-V Architecture
+
+config STARFIVE_WATCHDOG
+	tristate "StarFive Watchdog support"
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	select WATCHDOG_CORE
+	default ARCH_STARFIVE
+	help
+	  Say Y here to support the watchdog of StarFive JH7100 and JH7110
+	  SoC. This driver can also be built as a module if choose M.
+
 # S390 Architecture
 
 config DIAG288_WATCHDOG
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 9cbf6580f16c..b4c4ccf2d703 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -192,6 +192,9 @@ obj-$(CONFIG_MEN_A21_WDT) += mena21_wdt.o
 obj-$(CONFIG_PSERIES_WDT) += pseries-wdt.o
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o
 
+# RISC-V Architecture
+obj-$(CONFIG_STARFIVE_WATCHDOG) += starfive-wdt.o
+
 # S390 Architecture
 obj-$(CONFIG_DIAG288_WATCHDOG) += diag288_wdt.o
 
diff --git a/drivers/watchdog/starfive-wdt.c b/drivers/watchdog/starfive-wdt.c
new file mode 100644
index 000000000000..1995cceca51e
--- /dev/null
+++ b/drivers/watchdog/starfive-wdt.c
@@ -0,0 +1,606 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Starfive Watchdog driver
+ *
+ * Copyright (C) 2022 StarFive Technology Co., Ltd.
+ */
+
+#include <linux/clk.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+
+/* JH7100 Watchdog register define */
+#define STARFIVE_WDT_JH7100_INTSTAUS	0x000
+#define STARFIVE_WDT_JH7100_CONTROL	0x104
+#define STARFIVE_WDT_JH7100_LOAD	0x108
+#define STARFIVE_WDT_JH7100_EN		0x110
+#define STARFIVE_WDT_JH7100_RELOAD	0x114	/* Write 0 or 1 to reload preset value */
+#define STARFIVE_WDT_JH7100_VALUE	0x118
+#define STARFIVE_WDT_JH7100_INTCLR	0x120	/*
+						 * [0]: Write 1 to clear interrupt
+						 * [1]: 1 mean clearing and 0 mean complete
+						 * [31:2]: reserved.
+						 */
+#define STARFIVE_WDT_JH7100_LOCK	0x13c	/* write 0x378f0765 to unlock */
+
+/* JH7110 Watchdog register define */
+#define STARFIVE_WDT_JH7110_LOAD	0x000
+#define STARFIVE_WDT_JH7110_VALUE	0x004
+#define STARFIVE_WDT_JH7110_CONTROL	0x008	/*
+						 * [0]: reset enable;
+						 * [1]: interrupt enable && watchdog enable
+						 * [31:2]: reserved.
+						 */
+#define STARFIVE_WDT_JH7110_INTCLR	0x00c	/* clear intterupt and reload the counter */
+#define STARFIVE_WDT_JH7110_IMS		0x014
+#define STARFIVE_WDT_JH7110_LOCK	0xc00	/* write 0x1ACCE551 to unlock */
+
+/* WDOGCONTROL */
+#define STARFIVE_WDT_ENABLE			0x1
+#define STARFIVE_WDT_EN_SHIFT			0
+#define STARFIVE_WDT_RESET_EN			0x1
+#define STARFIVE_WDT_JH7100_RST_EN_SHIFT	0
+#define STARFIVE_WDT_JH7110_RST_EN_SHIFT	1
+
+/* WDOGLOCK */
+#define STARFIVE_WDT_JH7100_UNLOCK_KEY		0x378f0765
+#define STARFIVE_WDT_JH7110_UNLOCK_KEY		0x1acce551
+
+/* WDOGINTCLR */
+#define STARFIVE_WDT_INTCLR			0x1
+#define STARFIVE_WDT_JH7100_INTCLR_AVA_SHIFT	1	/* Watchdog can clear interrupt when 0 */
+
+#define STARFIVE_WDT_MAXCNT			0xffffffff
+#define STARFIVE_WDT_DEFAULT_TIME		(15)
+#define STARFIVE_WDT_DELAY_US			0
+#define STARFIVE_WDT_TIMEOUT_US			10000
+
+/* module parameter */
+#define STARFIVE_WDT_EARLY_ENA			0
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+static int heartbeat;
+static bool early_enable = STARFIVE_WDT_EARLY_ENA;
+
+module_param(heartbeat, int, 0);
+module_param(early_enable, bool, 0);
+module_param(nowayout, bool, 0);
+
+MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (default="
+		 __MODULE_STRING(STARFIVE_WDT_DEFAULT_TIME) ")");
+MODULE_PARM_DESC(early_enable,
+		 "Watchdog is started at boot time if set to 1, default="
+		 __MODULE_STRING(STARFIVE_WDT_EARLY_ENA));
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct starfive_wdt_variant {
+	unsigned int control;		/* Watchdog Control Resgister for reset enable */
+	unsigned int load;		/* Watchdog Load register */
+	unsigned int reload;		/* Watchdog Reload Control register */
+	unsigned int enable;		/* Watchdog Enable Register */
+	unsigned int value;		/* Watchdog Counter Value Register */
+	unsigned int int_clr;		/* Watchdog Interrupt Clear Register */
+	unsigned int unlock;		/* Watchdog Lock Register */
+	unsigned int int_status;	/* Watchdog Interrupt Status Register */
+
+	u32 unlock_key;
+	char enrst_shift;
+	char en_shift;
+	bool intclr_check;		/*  whether need to check it before clearing interrupt */
+	char intclr_ava_shift;
+	bool double_timeout;		/* The watchdog need twice timeout to reboot */
+};
+
+struct starfive_wdt {
+	struct watchdog_device wdd;
+	spinlock_t lock;		/* spinlock for register handling */
+	void __iomem *base;
+	struct clk *core_clk;
+	struct clk *apb_clk;
+	const struct starfive_wdt_variant *variant;
+	unsigned long freq;
+	u32 count;			/* count of timeout */
+	u32 reload;			/* restore the count */
+};
+
+/* Register layout and configuration for the JH7100 */
+static const struct starfive_wdt_variant starfive_wdt_jh7100_variant = {
+	.control = STARFIVE_WDT_JH7100_CONTROL,
+	.load = STARFIVE_WDT_JH7100_LOAD,
+	.reload = STARFIVE_WDT_JH7100_RELOAD,
+	.enable = STARFIVE_WDT_JH7100_EN,
+	.value = STARFIVE_WDT_JH7100_VALUE,
+	.int_clr = STARFIVE_WDT_JH7100_INTCLR,
+	.unlock = STARFIVE_WDT_JH7100_LOCK,
+	.unlock_key = STARFIVE_WDT_JH7100_UNLOCK_KEY,
+	.int_status = STARFIVE_WDT_JH7100_INTSTAUS,
+	.enrst_shift = STARFIVE_WDT_JH7100_RST_EN_SHIFT,
+	.en_shift = STARFIVE_WDT_EN_SHIFT,
+	.intclr_check = true,
+	.intclr_ava_shift = STARFIVE_WDT_JH7100_INTCLR_AVA_SHIFT,
+	.double_timeout = false,
+};
+
+/* Register layout and configuration for the JH7110 */
+static const struct starfive_wdt_variant starfive_wdt_jh7110_variant = {
+	.control = STARFIVE_WDT_JH7110_CONTROL,
+	.load = STARFIVE_WDT_JH7110_LOAD,
+	.enable = STARFIVE_WDT_JH7110_CONTROL,
+	.value = STARFIVE_WDT_JH7110_VALUE,
+	.int_clr = STARFIVE_WDT_JH7110_INTCLR,
+	.unlock = STARFIVE_WDT_JH7110_LOCK,
+	.unlock_key = STARFIVE_WDT_JH7110_UNLOCK_KEY,
+	.int_status = STARFIVE_WDT_JH7110_IMS,
+	.enrst_shift = STARFIVE_WDT_JH7110_RST_EN_SHIFT,
+	.en_shift = STARFIVE_WDT_EN_SHIFT,
+	.intclr_check = false,
+	.double_timeout = true,
+};
+
+static int starfive_wdt_enable_clock(struct starfive_wdt *wdt)
+{
+	int ret;
+
+	ret = clk_prepare_enable(wdt->apb_clk);
+	if (ret)
+		return dev_err_probe(wdt->wdd.parent, ret, "failed to enable apb clock\n");
+
+	ret = clk_prepare_enable(wdt->core_clk);
+	if (ret)
+		return dev_err_probe(wdt->wdd.parent, ret, "failed to enable core clock\n");
+
+	return 0;
+}
+
+static void starfive_wdt_disable_clock(struct starfive_wdt *wdt)
+{
+	clk_disable_unprepare(wdt->core_clk);
+	clk_disable_unprepare(wdt->apb_clk);
+}
+
+static inline int starfive_wdt_get_clock(struct starfive_wdt *wdt)
+{
+	struct device *dev = wdt->wdd.parent;
+
+	wdt->apb_clk = devm_clk_get(dev, "apb");
+	if (IS_ERR(wdt->apb_clk))
+		return dev_err_probe(dev, PTR_ERR(wdt->apb_clk), "failed to get apb clock\n");
+
+	wdt->core_clk = devm_clk_get(dev, "core");
+	if (IS_ERR(wdt->core_clk))
+		return dev_err_probe(dev, PTR_ERR(wdt->core_clk), "failed to get core clock\n");
+
+	return 0;
+}
+
+static inline int starfive_wdt_reset_init(struct device *dev)
+{
+	struct reset_control *rsts;
+	int ret;
+
+	rsts = devm_reset_control_array_get_exclusive(dev);
+	if (IS_ERR(rsts))
+		return dev_err_probe(dev, PTR_ERR(rsts), "failed to get resets\n");
+
+	ret = reset_control_deassert(rsts);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to deassert resets\n");
+
+	return 0;
+}
+
+static u32 starfive_wdt_ticks_to_sec(struct starfive_wdt *wdt, u32 ticks)
+{
+	return DIV_ROUND_CLOSEST(ticks, wdt->freq);
+}
+
+/* Write unlock-key to unlock. Write other value to lock. */
+static void starfive_wdt_unlock(struct starfive_wdt *wdt)
+{
+	spin_lock(&wdt->lock);
+	writel(wdt->variant->unlock_key, wdt->base + wdt->variant->unlock);
+}
+
+static void starfive_wdt_lock(struct starfive_wdt *wdt)
+{
+	writel(~wdt->variant->unlock_key, wdt->base + wdt->variant->unlock);
+	spin_unlock(&wdt->lock);
+}
+
+/* enable watchdog interrupt to reset/reboot */
+static void starfive_wdt_enable_reset(struct starfive_wdt *wdt)
+{
+	u32 val;
+
+	val = readl(wdt->base + wdt->variant->control);
+	val |= STARFIVE_WDT_RESET_EN << wdt->variant->enrst_shift;
+	writel(val, wdt->base + wdt->variant->control);
+}
+
+/* interrupt status whether has been raised from the counter */
+static bool starfive_wdt_raise_irq_status(struct starfive_wdt *wdt)
+{
+	return !!readl(wdt->base + wdt->variant->int_status);
+}
+
+/* waiting interrupt can be free to clear */
+static int starfive_wdt_wait_int_free(struct starfive_wdt *wdt)
+{
+	u32 value;
+
+	return readl_poll_timeout_atomic(wdt->base + wdt->variant->int_clr, value,
+					 !(value & BIT(wdt->variant->intclr_ava_shift)),
+					 STARFIVE_WDT_DELAY_US, STARFIVE_WDT_TIMEOUT_US);
+}
+
+/* clear interrupt signal before initialization or reload */
+static int starfive_wdt_int_clr(struct starfive_wdt *wdt)
+{
+	int ret;
+
+	if (wdt->variant->intclr_check) {
+		ret = starfive_wdt_wait_int_free(wdt);
+		if (ret)
+			return dev_err_probe(wdt->wdd.parent, ret,
+					     "watchdog is not ready to clear interrupt.\n");
+	}
+	writel(STARFIVE_WDT_INTCLR, wdt->base + wdt->variant->int_clr);
+
+	return 0;
+}
+
+static inline void starfive_wdt_set_count(struct starfive_wdt *wdt, u32 val)
+{
+	writel(val, wdt->base + wdt->variant->load);
+}
+
+static inline u32 starfive_wdt_get_count(struct starfive_wdt *wdt)
+{
+	return readl(wdt->base + wdt->variant->value);
+}
+
+/* enable watchdog */
+static inline void starfive_wdt_enable(struct starfive_wdt *wdt)
+{
+	u32 val;
+
+	val = readl(wdt->base + wdt->variant->enable);
+	val |= STARFIVE_WDT_ENABLE << wdt->variant->en_shift;
+	writel(val, wdt->base + wdt->variant->enable);
+}
+
+/* disable watchdog */
+static inline void starfive_wdt_disable(struct starfive_wdt *wdt)
+{
+	u32 val;
+
+	val = readl(wdt->base + wdt->variant->enable);
+	val &= ~(STARFIVE_WDT_ENABLE << wdt->variant->en_shift);
+	writel(val, wdt->base + wdt->variant->enable);
+}
+
+static inline void starfive_wdt_set_reload_count(struct starfive_wdt *wdt, u32 count)
+{
+	starfive_wdt_set_count(wdt, count);
+
+	/* 7100 need set any value to reload register and could reload value to counter */
+	if (wdt->variant->reload)
+		writel(0x1, wdt->base + wdt->variant->reload);
+}
+
+static unsigned int starfive_wdt_max_timeout(struct starfive_wdt *wdt)
+{
+	if (wdt->variant->double_timeout)
+		return DIV_ROUND_UP(STARFIVE_WDT_MAXCNT, (wdt->freq / 2)) - 1;
+
+	return DIV_ROUND_UP(STARFIVE_WDT_MAXCNT, wdt->freq) - 1;
+}
+
+static unsigned int starfive_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
+	u32 count;
+
+	/*
+	 * If the watchdog takes twice timeout and set half count value,
+	 * timeleft value should add the count value before first timeout.
+	 */
+	count = starfive_wdt_get_count(wdt);
+	if (wdt->variant->double_timeout && !starfive_wdt_raise_irq_status(wdt))
+		count += wdt->count;
+
+	return starfive_wdt_ticks_to_sec(wdt, count);
+}
+
+static int starfive_wdt_keepalive(struct watchdog_device *wdd)
+{
+	struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	starfive_wdt_unlock(wdt);
+	ret = starfive_wdt_int_clr(wdt);
+	if (ret)
+		goto exit;
+
+	starfive_wdt_set_reload_count(wdt, wdt->count);
+
+exit:
+	/* exit with releasing spinlock and locking registers */
+	starfive_wdt_lock(wdt);
+	return ret;
+}
+
+static int starfive_wdt_start(struct starfive_wdt *wdt)
+{
+	int ret;
+
+	starfive_wdt_unlock(wdt);
+	/* disable watchdog, to be safe */
+	starfive_wdt_disable(wdt);
+
+	starfive_wdt_enable_reset(wdt);
+	ret = starfive_wdt_int_clr(wdt);
+	if (ret)
+		goto exit;
+
+	starfive_wdt_set_count(wdt, wdt->count);
+	starfive_wdt_enable(wdt);
+
+exit:
+	starfive_wdt_lock(wdt);
+	return ret;
+}
+
+static void starfive_wdt_stop(struct starfive_wdt *wdt)
+{
+	starfive_wdt_unlock(wdt);
+	starfive_wdt_disable(wdt);
+	starfive_wdt_lock(wdt);
+}
+
+static int starfive_wdt_pm_start(struct watchdog_device *wdd)
+{
+	struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
+	int ret = pm_runtime_get_sync(wdd->parent);
+
+	if (ret < 0)
+		return ret;
+
+	return starfive_wdt_start(wdt);
+}
+
+static int starfive_wdt_pm_stop(struct watchdog_device *wdd)
+{
+	struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	starfive_wdt_stop(wdt);
+	return pm_runtime_put_sync(wdd->parent);
+}
+
+static int starfive_wdt_set_timeout(struct watchdog_device *wdd,
+				    unsigned int timeout)
+{
+	struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
+	unsigned long count = timeout * wdt->freq;
+
+	/* some watchdogs take two timeouts to reset */
+	if (wdt->variant->double_timeout)
+		count /= 2;
+
+	wdt->count = count;
+	wdd->timeout = timeout;
+
+	starfive_wdt_unlock(wdt);
+	starfive_wdt_disable(wdt);
+	starfive_wdt_set_reload_count(wdt, wdt->count);
+	starfive_wdt_enable(wdt);
+	starfive_wdt_lock(wdt);
+
+	return 0;
+}
+
+#define STARFIVE_WDT_OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
+
+static const struct watchdog_info starfive_wdt_info = {
+	.options = STARFIVE_WDT_OPTIONS,
+	.identity = "StarFive Watchdog",
+};
+
+static const struct watchdog_ops starfive_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = starfive_wdt_pm_start,
+	.stop = starfive_wdt_pm_stop,
+	.ping = starfive_wdt_keepalive,
+	.set_timeout = starfive_wdt_set_timeout,
+	.get_timeleft = starfive_wdt_get_timeleft,
+};
+
+static int starfive_wdt_probe(struct platform_device *pdev)
+{
+	struct starfive_wdt *wdt;
+	int ret;
+
+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdt->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(wdt->base))
+		return dev_err_probe(&pdev->dev, PTR_ERR(wdt->base), "error mapping registers\n");
+
+	wdt->wdd.parent = &pdev->dev;
+	ret = starfive_wdt_get_clock(wdt);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, wdt);
+	pm_runtime_enable(&pdev->dev);
+	if (pm_runtime_enabled(&pdev->dev)) {
+		ret = pm_runtime_get_sync(&pdev->dev);
+		if (ret < 0)
+			return ret;
+	} else {
+		/* runtime PM is disabled but clocks need to be enabled */
+		ret = starfive_wdt_enable_clock(wdt);
+		if (ret)
+			return ret;
+	}
+
+	ret = starfive_wdt_reset_init(&pdev->dev);
+	if (ret)
+		goto err_exit;
+
+	watchdog_set_drvdata(&wdt->wdd, wdt);
+	wdt->wdd.info = &starfive_wdt_info;
+	wdt->wdd.ops = &starfive_wdt_ops;
+	wdt->variant = of_device_get_match_data(&pdev->dev);
+	spin_lock_init(&wdt->lock);
+
+	wdt->freq = clk_get_rate(wdt->core_clk);
+	if (!wdt->freq) {
+		dev_err(&pdev->dev, "get clock rate failed.\n");
+		ret = -EINVAL;
+		goto err_exit;
+	}
+
+	wdt->wdd.min_timeout = 1;
+	wdt->wdd.max_timeout = starfive_wdt_max_timeout(wdt);
+	wdt->wdd.timeout = STARFIVE_WDT_DEFAULT_TIME;
+	watchdog_init_timeout(&wdt->wdd, heartbeat, &pdev->dev);
+	starfive_wdt_set_timeout(&wdt->wdd, wdt->wdd.timeout);
+
+	watchdog_set_nowayout(&wdt->wdd, nowayout);
+	watchdog_stop_on_reboot(&wdt->wdd);
+	watchdog_stop_on_unregister(&wdt->wdd);
+
+	if (early_enable) {
+		ret = starfive_wdt_start(wdt);
+		if (ret)
+			goto err_exit;
+		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+	} else {
+		starfive_wdt_stop(wdt);
+	}
+
+	ret = watchdog_register_device(&wdt->wdd);
+	if (ret)
+		goto err_exit;
+
+	if (!early_enable)
+		return pm_runtime_put_sync(&pdev->dev);
+
+	return 0;
+
+err_exit:
+	starfive_wdt_disable_clock(wdt);
+	pm_runtime_disable(&pdev->dev);
+
+	return ret;
+}
+
+static int starfive_wdt_remove(struct platform_device *pdev)
+{
+	struct starfive_wdt *wdt = platform_get_drvdata(pdev);
+
+	starfive_wdt_stop(wdt);
+	watchdog_unregister_device(&wdt->wdd);
+
+	if (pm_runtime_enabled(&pdev->dev))
+		pm_runtime_disable(&pdev->dev);
+	else
+		/* disable clock without PM */
+		starfive_wdt_disable_clock(wdt);
+
+	return 0;
+}
+
+static void starfive_wdt_shutdown(struct platform_device *pdev)
+{
+	struct starfive_wdt *wdt = platform_get_drvdata(pdev);
+
+	starfive_wdt_pm_stop(&wdt->wdd);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int starfive_wdt_suspend(struct device *dev)
+{
+	struct starfive_wdt *wdt = dev_get_drvdata(dev);
+
+	/* Save watchdog state, and turn it off. */
+	wdt->reload = starfive_wdt_get_count(wdt);
+
+	/* Note that WTCNT doesn't need to be saved. */
+	starfive_wdt_stop(wdt);
+
+	return pm_runtime_force_suspend(dev);
+}
+
+static int starfive_wdt_resume(struct device *dev)
+{
+	struct starfive_wdt *wdt = dev_get_drvdata(dev);
+	int ret;
+
+	ret = pm_runtime_force_resume(dev);
+	if (ret)
+		return ret;
+
+	starfive_wdt_unlock(wdt);
+	/* Restore watchdog state. */
+	starfive_wdt_set_reload_count(wdt, wdt->reload);
+	starfive_wdt_lock(wdt);
+
+	return starfive_wdt_start(wdt);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_PM
+static int starfive_wdt_runtime_suspend(struct device *dev)
+{
+	struct starfive_wdt *wdt = dev_get_drvdata(dev);
+
+	starfive_wdt_disable_clock(wdt);
+
+	return 0;
+}
+
+static int starfive_wdt_runtime_resume(struct device *dev)
+{
+	struct starfive_wdt *wdt = dev_get_drvdata(dev);
+
+	return starfive_wdt_enable_clock(wdt);
+}
+#endif /* CONFIG_PM */
+
+static const struct dev_pm_ops starfive_wdt_pm_ops = {
+	SET_RUNTIME_PM_OPS(starfive_wdt_runtime_suspend, starfive_wdt_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(starfive_wdt_suspend, starfive_wdt_resume)
+};
+
+static const struct of_device_id starfive_wdt_match[] = {
+	{ .compatible = "starfive,jh7100-wdt", .data = &starfive_wdt_jh7100_variant },
+	{ .compatible = "starfive,jh7110-wdt", .data = &starfive_wdt_jh7110_variant },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, starfive_wdt_match);
+
+static struct platform_driver starfive_wdt_driver = {
+	.probe = starfive_wdt_probe,
+	.remove = starfive_wdt_remove,
+	.shutdown = starfive_wdt_shutdown,
+	.driver = {
+		.name = "starfive-wdt",
+		.pm = &starfive_wdt_pm_ops,
+		.of_match_table = of_match_ptr(starfive_wdt_match),
+	},
+};
+module_platform_driver(starfive_wdt_driver);
+
+MODULE_AUTHOR("Xingyu Wu <xingyu.wu@xxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Samin Guo <samin.guo@xxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("StarFive Watchdog Device Driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1