Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 725 insertions, 0 deletions

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
new file mode 100644
index 000000000..3cd118281
--- /dev/null
+++ b/drivers/watchdog/dw_wdt.c
@@ -0,0 +1,725 @@
+// 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/limits.h>
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+#include <linux/debugfs.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 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;
+}
+
+#ifdef CONFIG_PM_SLEEP
+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;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static 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(dev, "tclk");
+	if (IS_ERR(dw_wdt->clk)) {
+		dw_wdt->clk = devm_clk_get(dev, NULL);
+		if (IS_ERR(dw_wdt->clk))
+			return PTR_ERR(dw_wdt->clk);
+	}
+
+	ret = clk_prepare_enable(dw_wdt->clk);
+	if (ret)
+		return ret;
+
+	dw_wdt->rate = clk_get_rate(dw_wdt->clk);
+	if (dw_wdt->rate == 0) {
+		ret = -EINVAL;
+		goto out_disable_clk;
+	}
+
+	/*
+	 * 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(dev, "pclk");
+	if (IS_ERR(dw_wdt->pclk)) {
+		ret = PTR_ERR(dw_wdt->pclk);
+		goto out_disable_clk;
+	}
+
+	ret = clk_prepare_enable(dw_wdt->pclk);
+	if (ret)
+		goto out_disable_clk;
+
+	dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
+	if (IS_ERR(dw_wdt->rst)) {
+		ret = PTR_ERR(dw_wdt->rst);
+		goto out_disable_pclk;
+	}
+
+	/* 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)
+			goto out_disable_pclk;
+
+		dw_wdt->wdd.info = &dw_wdt_pt_ident;
+	} else {
+		if (ret == -EPROBE_DEFER)
+			goto out_disable_pclk;
+
+		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);
+	}
+
+	platform_set_drvdata(pdev, dw_wdt);
+
+	watchdog_set_restart_priority(wdd, 128);
+
+	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);
+
+out_disable_pclk:
+	clk_disable_unprepare(dw_wdt->pclk);
+
+out_disable_clk:
+	clk_disable_unprepare(dw_wdt->clk);
+	return ret;
+}
+
+static int 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);
+	clk_disable_unprepare(dw_wdt->pclk);
+	clk_disable_unprepare(dw_wdt->clk);
+
+	return 0;
+}
+
+#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	= &dw_wdt_pm_ops,
+	},
+};
+
+module_platform_driver(dw_wdt_driver);
+
+MODULE_AUTHOR("Jamie Iles");
+MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
+MODULE_LICENSE("GPL");