Message-Id: <1431689090-3125-2-git-send-email-fu.wei@linaro.org>
Date:	Fri, 15 May 2015 19:24:49 +0800
From:	fu.wei@...aro.org
To:	Suravee.Suthikulpanit@....com, linaro-acpi@...ts.linaro.org,
	linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Cc:	tekkamanninja@...il.com, graeme.gregory@...aro.org,
	al.stone@...aro.org, hanjun.guo@...aro.org, timur@...eaurora.org,
	ashwin.chaugule@...aro.org, arnd@...db.de, linux@...ck-us.net,
	vgandhi@...eaurora.org, wim@...ana.be, jcm@...hat.com,
	leo.duran@....com, corbet@....net, Fu Wei <fu.wei@...aro.org>
Subject: [PATCH 5/6] Watchdog: introdouce ARM SBSA watchdog driver

From: Fu Wei <fu.wei@...aro.org>

    (1)Use linux kernel watchdog framework
    (2)Work with FDT on ARM64
    (3)Use "pretimeout" in watchdog framework
    (4)In first timeout(WS0), do panic to save system context
    (5)support geting timeout and pretimeout from
       parameter and FDT at the driver init stage.

Signed-off-by: Fu Wei <fu.wei@...aro.org>
---
 drivers/watchdog/Kconfig     |  10 +
 drivers/watchdog/Makefile    |   1 +
 drivers/watchdog/sbsa_gwdt.c | 553 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 564 insertions(+)
 create mode 100644 drivers/watchdog/sbsa_gwdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e5e7c55..1e1bc8b 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -152,6 +152,16 @@ config ARM_SP805_WATCHDOG
 	  ARM Primecell SP805 Watchdog timer. This will reboot your system when
 	  the timeout is reached.
 
+config ARM_SBSA_WATCHDOG
+	tristate "ARM SBSA Generic Watchdog"
+	depends on ARM || ARM64 || COMPILE_TEST
+	select WATCHDOG_CORE
+	help
+	  ARM SBSA Generic Watchdog timer. This has two Watchdog Signal(WS0/WS1),
+	  will trigger a warnning interrupt(do panic) in the first timeout(WS0);
+	  will reboot your system when the second timeout(WS1) is reached.
+	  More details: DEN0029B - Server Base System Architecture (SBSA)
+
 config AT91RM9200_WATCHDOG
 	tristate "AT91RM9200 watchdog"
 	depends on SOC_AT91RM9200 && MFD_SYSCON
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 5c19294..471f1b7c 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
 
 # ARM Architecture
 obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
+obj-$(CONFIG_ARM_SBSA_WATCHDOG) += sbsa_gwdt.o
 obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
 obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
 obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o
diff --git a/drivers/watchdog/sbsa_gwdt.c b/drivers/watchdog/sbsa_gwdt.c
new file mode 100644
index 0000000..52838b1
--- /dev/null
+++ b/drivers/watchdog/sbsa_gwdt.c
@@ -0,0 +1,553 @@
+/*
+ * SBSA(Server Base System Architecture) Generic Watchdog driver
+ *
+ * Copyright (c) 2015, Linaro Ltd.
+ * Author: Fu Wei <fu.wei@...aro.org>
+ *         Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Note: This SBSA Generic watchdog driver is compatible with
+ *       the pretimeout concept of Linux kernel.
+ *       But timeout and pretimeout are set by the different REGs.
+ *       The first watch period is set by writing WCV directly,
+ *       that can support more than 10s timeout at the maximum
+ *       system counter frequency.
+ *       And the second watch period is set by WOR(32bit) which will be loaded
+ *       automatically by hardware, when WS0 is triggered.
+ *       This gives a maximum watch period of around 10s at the maximum
+ *       system counter frequency.
+ *       The System Counter shall run at maximum of 400MHz.
+ *       More details: DEN0029B - Server Base System Architecture (SBSA)
+ *
+ * Kernel/API:                         P---------| pretimeout
+ *               |-------------------------------T timeout
+ * SBSA GWDT:                          P--WOR---WS1 pretimeout
+ *               |-------WCV----------WS0~~~~~~~~T timeout
+ */
+
+#include <asm/arch_timer.h>
+
+#include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+
+/* SBSA Generic Watchdog register definitions */
+/* refresh frame */
+#define SBSA_GWDT_WRR				0x000
+
+/* control frame */
+#define SBSA_GWDT_WCS				0x000
+#define SBSA_GWDT_WOR				0x008
+#define SBSA_GWDT_WCV_LO			0x010
+#define SBSA_GWDT_WCV_HI			0x014
+
+/* refresh/control frame */
+#define SBSA_GWDT_W_IIDR			0xfcc
+#define SBSA_GWDT_IDR				0xfd0
+
+/* Watchdog Control and Status Register */
+#define SBSA_GWDT_WCS_EN			BIT(0)
+#define SBSA_GWDT_WCS_WS0			BIT(1)
+#define SBSA_GWDT_WCS_WS1			BIT(2)
+
+/* Watchdog Interface Identification Register */
+#define SBSA_GWDT_W_IIDR_PID(x)			((x >> 20) & 0xfff)
+#define SBSA_GWDT_W_IIDR_ARCH_VER(x)		((x >> 16) & 0xf)
+#define SBSA_GWDT_W_IIDR_REV(x)			((x >> 12) & 0xf)
+#define SBSA_GWDT_W_IIDR_IMPLEMENTER(x)		(x & 0xfff)
+#define SBSA_GWDT_W_IIDR_VID_BANK(x)		((x >> 8) & 0xf)
+#define SBSA_GWDT_W_IIDR_VID(x)			(x & 0x7f)
+
+/* Watchdog Identification Register */
+#define SBSA_GWDT_IDR_W_PIDR2			0xfe8
+#define SBSA_GWDT_IDR_W_PIDR2_ARCH_VER(x)	((x >> 4) & 0xf)
+
+/**
+ * struct sbsa_gwdt - Internal representation of the SBSA GWDT
+ * @wdd:		kernel watchdog_device structure
+ * @clk:		store the System Counter clock frequency, in Hz.
+ * @refresh_base:	VA of the watchdog refresh frame
+ * @control_base:	VA of the watchdog control frame
+ * @lock:		struct sbsa_gwdt spinlock
+ * @pm_status_store:	store the PM info of WDT
+ */
+struct sbsa_gwdt {
+	struct watchdog_device	wdd;
+	u32			clk;
+	void __iomem		*refresh_base;
+	void __iomem		*control_base;
+#ifdef CONFIG_PM_SLEEP
+	spinlock_t		lock;
+	u8			pm_status_store;
+#endif
+};
+
+#define to_sbsa_gwdt(e) container_of(e, struct sbsa_gwdt, wdd)
+
+#define DEFAULT_TIMEOUT_WS0	10 /* seconds, the 1st watch period*/
+#define DEFAULT_PRETIMEOUT	5 /* seconds, the 2nd watch period*/
+
+static unsigned int timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout,
+		 "Watchdog timeout in seconds. (>=0, default="
+		 __MODULE_STRING(DEFAULT_TIMEOUT_WS0 + DEFAULT_PRETIMEOUT) ")");
+
+static unsigned int max_timeout = UINT_MAX;
+module_param(max_timeout, uint, 0);
+MODULE_PARM_DESC(max_timeout,
+		 "Watchdog max timeout in seconds. (>=0, default="
+		 __MODULE_STRING(UINT_MAX) ")");
+
+static unsigned int max_pretimeout = U32_MAX;
+module_param(max_pretimeout, uint, 0);
+MODULE_PARM_DESC(max_pretimeout,
+		 "Watchdog max pretimeout in seconds. (>=0, default="
+		 __MODULE_STRING(U32_MAX) ")");
+
+static unsigned int pretimeout;
+module_param(pretimeout, uint, 0);
+MODULE_PARM_DESC(pretimeout,
+		 "Watchdog pretimeout in seconds. (>=0, default="
+		 __MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, S_IRUGO);
+MODULE_PARM_DESC(nowayout,
+		 "Watchdog cannot be stopped once started (default="
+		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+/*
+ * Architected system timer support.
+ */
+static void sbsa_gwdt_cf_write(unsigned int reg, u32 val,
+			       struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+
+	writel_relaxed(val, gwdt->control_base + reg);
+}
+
+static void sbsa_gwdt_rf_write(unsigned int reg, u32 val,
+			       struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+
+	writel_relaxed(val, gwdt->refresh_base + reg);
+}
+
+static u32 sbsa_gwdt_cf_read(unsigned int reg, struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+
+	return readl_relaxed(gwdt->control_base + reg);
+}
+
+/*
+ * help founctions for accessing 64bit WCV register
+ * mutex_lock must be called prior to calling this function.
+ */
+static u64 sbsa_gwdt_get_wcv(struct watchdog_device *wdd)
+{
+	u32 wcv_lo, wcv_hi;
+
+	do {
+		wcv_hi = sbsa_gwdt_cf_read(SBSA_GWDT_WCV_HI, wdd);
+		wcv_lo = sbsa_gwdt_cf_read(SBSA_GWDT_WCV_LO, wdd);
+	} while (wcv_hi != sbsa_gwdt_cf_read(SBSA_GWDT_WCV_HI, wdd));
+
+	return (((u64)wcv_hi << 32) | wcv_lo);
+}
+
+static void sbsa_gwdt_set_wcv(struct watchdog_device *wdd, u64 value)
+{
+	u32 wcv_lo, wcv_hi;
+
+	wcv_lo = value & U32_MAX;
+	wcv_hi = (value >> 32) & U32_MAX;
+
+	sbsa_gwdt_cf_write(SBSA_GWDT_WCV_HI, wcv_hi, wdd);
+	sbsa_gwdt_cf_write(SBSA_GWDT_WCV_LO, wcv_lo, wdd);
+
+	pr_debug("sbsa_gwdt: set WCV to %llu, result: %llu\n",
+		 value, sbsa_gwdt_get_wcv(wdd));
+}
+
+static void reload_timeout_to_wcv(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+	u64 wcv;
+
+	wcv = arch_counter_get_cntvct() +
+		(u64)(wdd->timeout - wdd->pretimeout) * gwdt->clk;
+
+	sbsa_gwdt_set_wcv(wdd, wcv);
+}
+
+/*
+ * Use the following function to set the limit of timeout
+ * after updating pretimeout
+ */
+static void sbsa_gwdt_set_timeout_limits(struct sbsa_gwdt *gwdt)
+{
+	unsigned int first_period_max = (U64_MAX / gwdt->clk);
+	struct watchdog_device *wdd = &gwdt->wdd;
+
+	wdd->min_timeout = wdd->pretimeout + 1;
+	wdd->max_timeout = min(wdd->pretimeout + first_period_max, max_timeout);
+
+	pr_debug("sbsa_gwdt: timeout (%u-%u), pretimeout (%u-%u)\n",
+		 wdd->min_timeout, wdd->max_timeout,
+		 wdd->min_pretimeout, wdd->max_pretimeout);
+}
+
+static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd,
+				 unsigned int timeout)
+{
+	wdd->timeout = timeout;
+
+	return 0;
+	/* watchdog framework will trigger a ping, after this call */
+}
+
+static int sbsa_gwdt_set_pretimeout(struct watchdog_device *wdd,
+				    unsigned int pretimeout)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+	u32 wor;
+
+	wdd->pretimeout = pretimeout;
+	sbsa_gwdt_set_timeout_limits(gwdt);
+
+	if (!pretimeout)
+		/* gives sbsa_gwdt_start a chance to setup timeout */
+		wor = gwdt->clk;
+	else
+		wor = pretimeout * gwdt->clk;
+
+	/* refresh the WOR, that will cause an explicit watchdog refresh */
+	sbsa_gwdt_cf_write(SBSA_GWDT_WOR, wor, wdd);
+
+	pr_debug("sbsa_gwdt: set WOR to %x(%us), result: %x\n",
+		 wor, pretimeout, sbsa_gwdt_cf_read(SBSA_GWDT_WOR, wdd));
+
+	return 0;
+	/* watchdog framework will trigger a ping, after this call */
+}
+
+static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct sbsa_gwdt *gwdt = to_sbsa_gwdt(wdd);
+	u64 timeleft = sbsa_gwdt_get_wcv(wdd) - arch_counter_get_cntvct();
+
+	return timeleft / gwdt->clk;
+}
+
+static int sbsa_gwdt_start(struct watchdog_device *wdd)
+{
+	/* Force refresh */
+	sbsa_gwdt_rf_write(SBSA_GWDT_WRR, 0xc0ffee, wdd);
+	/* writing WCS will cause an explicit watchdog refresh */
+	sbsa_gwdt_cf_write(SBSA_GWDT_WCS, SBSA_GWDT_WCS_EN, wdd);
+
+	reload_timeout_to_wcv(wdd);
+
+	pr_debug("sbsa_gwdt: WCS is %x(%s)\n",
+		 sbsa_gwdt_cf_read(SBSA_GWDT_WCS, wdd), __func__);
+
+	return 0;
+}
+
+static int sbsa_gwdt_stop(struct watchdog_device *wdd)
+{
+	/* Force refresh */
+	sbsa_gwdt_rf_write(SBSA_GWDT_WRR, 0xc0ffee, wdd);
+	/* writing WCS will cause an explicit watchdog refresh */
+	sbsa_gwdt_cf_write(SBSA_GWDT_WCS, 0, wdd);
+
+	pr_debug("sbsa_gwdt: WCS is %x(%s)\n",
+		 sbsa_gwdt_cf_read(SBSA_GWDT_WCS, wdd), __func__);
+
+	return 0;
+}
+
+static int sbsa_gwdt_keepalive(struct watchdog_device *wdd)
+{
+	/*
+	 * Writing WRR for an explicit watchdog refresh
+	 * You can write anyting(like 0xc0ffee)
+	 */
+	sbsa_gwdt_rf_write(SBSA_GWDT_WRR, 0xc0ffee, wdd);
+
+	reload_timeout_to_wcv(wdd);
+
+	pr_debug("sbsa_gwdt: ping, %us left.\n", sbsa_gwdt_get_timeleft(wdd));
+
+	return 0;
+}
+
+static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id)
+{
+	struct sbsa_gwdt *gwdt = (struct sbsa_gwdt *)dev_id;
+	struct watchdog_device *wdd = &gwdt->wdd;
+	u32 status;
+
+	status = sbsa_gwdt_cf_read(SBSA_GWDT_WCS, wdd);
+
+	pr_debug("sbsa_gwdt: interrupt routine, WCS@%x\n", status);
+
+	if (status & SBSA_GWDT_WCS_WS0) {
+		pr_debug("sbsa_gwdt WS0: trigger WS1 in %ds!\n",
+			 sbsa_gwdt_get_timeleft(wdd));
+		panic("SBSA Watchdog pre-timeout");
+	}
+
+	return IRQ_HANDLED;
+}
+
+static struct watchdog_info sbsa_gwdt_info = {
+	.identity	= "SBSA Generic Watchdog",
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE |
+			  WDIOF_PRETIMEOUT |
+			  WDIOF_CARDRESET,
+};
+
+static struct watchdog_ops sbsa_gwdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= sbsa_gwdt_start,
+	.stop		= sbsa_gwdt_stop,
+	.ping		= sbsa_gwdt_keepalive,
+	.set_timeout	= sbsa_gwdt_set_timeout,
+	.set_pretimeout	= sbsa_gwdt_set_pretimeout,
+	.get_timeleft	= sbsa_gwdt_get_timeleft,
+};
+
+static int sbsa_gwdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	struct sbsa_gwdt *gwdt;
+	struct watchdog_device *wdd;
+
+	struct resource *res;
+	void *rf_base, *cf_base;
+	int irq;
+	u32 clk, status, w_iidr;
+
+	int ret = 0;
+
+	/*
+	 * Try to determine the frequency from the cp15 interface
+	 */
+	clk = arch_timer_get_cntfrq();
+	if (!clk) {
+		dev_err(dev, "System Counter frequency not available\n");
+		return -EINVAL;
+	}
+
+	gwdt = devm_kzalloc(dev, sizeof(*gwdt), GFP_KERNEL);
+	if (!gwdt)
+		return -ENOMEM;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "refresh");
+	rf_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(rf_base))
+		return PTR_ERR(rf_base);
+
+	pr_debug("sbsa_gwdt: ioremap %s frame 0x%llx(size: %llu)-->%p.\n",
+		 res->name, (unsigned long long)res->start,
+		(unsigned long long)(res->end - res->start + 1), rf_base);
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "control");
+	cf_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(rf_base))
+		return PTR_ERR(rf_base);
+
+	pr_debug("sbsa_gwdt: ioremap %s frame 0x%llx(size: %llu)-->%p.\n",
+		 res->name, (unsigned long long)res->start,
+		(unsigned long long)(res->end - res->start + 1), cf_base);
+
+	irq = platform_get_irq_byname(pdev, "ws0");
+	if (irq < 0) {
+		dev_err(dev, "unable to get ws0 interrupt.\n");
+		return irq;
+	}
+
+	pr_debug("sbsa_gwdt: ws0 irq %d.\n", irq);
+
+	gwdt->refresh_base = rf_base;
+	gwdt->control_base = cf_base;
+	gwdt->clk = clk;
+#ifdef CONFIG_PM_SLEEP
+	spin_lock_init(&gwdt->lock);
+#endif
+	platform_set_drvdata(pdev, gwdt);
+
+	pr_debug("sbsa_gwdt: hw clk: %uHz--> WOR(32bit) max timeout is %us.\n",
+		 gwdt->clk, U32_MAX / clk);
+
+	wdd = &gwdt->wdd;
+	wdd->parent = dev;
+	wdd->info = &sbsa_gwdt_info;
+	wdd->ops = &sbsa_gwdt_ops;
+	watchdog_set_drvdata(wdd, gwdt);
+	watchdog_set_nowayout(wdd, nowayout);
+
+	status = sbsa_gwdt_cf_read(SBSA_GWDT_WCS, wdd);
+	if (status & SBSA_GWDT_WCS_WS1) {
+		dev_warn(dev, "System was reseted by WDT(WCS: %x, WCV: %llx)\n",
+			 status, sbsa_gwdt_get_wcv(wdd));
+		wdd->bootstatus |= WDIOF_CARDRESET;
+	}
+	/* Check if watchdog is already enabled */
+	if (status & SBSA_GWDT_WCS_EN) {
+		dev_warn(dev, "already enabled!\n");
+		sbsa_gwdt_keepalive(wdd);
+	}
+
+	pr_debug("sbsa_gwdt: WCS: %x(%s)\n", status, __func__);
+
+	wdd->min_pretimeout = 0;
+	wdd->max_pretimeout = min(U32_MAX / clk, max_timeout - 1);
+	sbsa_gwdt_set_timeout_limits(gwdt);
+
+	watchdog_init_pretimeout(wdd, pretimeout, dev);
+	if (!wdd->pretimeout) {
+		wdd->pretimeout = DEFAULT_PRETIMEOUT;
+		dev_info(dev, "can't get pretimeout param, set default %us.\n",
+			 wdd->pretimeout);
+	}
+	sbsa_gwdt_set_pretimeout(wdd, wdd->pretimeout);
+
+	watchdog_init_timeout(wdd, timeout, dev);
+	if (!wdd->timeout) {
+		wdd->timeout = wdd->pretimeout + DEFAULT_TIMEOUT_WS0;
+		dev_info(dev, "can't get timeout param, set default: %us.\n",
+			 wdd->timeout);
+	}
+	sbsa_gwdt_set_timeout(wdd, wdd->timeout);
+
+	ret = devm_request_irq(dev, irq, sbsa_gwdt_interrupt, IRQF_TIMER,
+			       pdev->name, gwdt);
+	if (ret) {
+		dev_err(dev, "unable to request IRQ %d\n", irq);
+		return ret;
+	}
+
+	ret = watchdog_register_device(wdd);
+	if (ret)
+		return ret;
+
+	/* get device information from control frame and display */
+	w_iidr = sbsa_gwdt_cf_read(SBSA_GWDT_W_IIDR, &gwdt->wdd);
+	dev_info(dev, "PID:%u(JEP106 %u-%u), Arch v%u Rev %u.",
+		 SBSA_GWDT_W_IIDR_PID(w_iidr),
+		 SBSA_GWDT_W_IIDR_VID_BANK(w_iidr),
+		 SBSA_GWDT_W_IIDR_VID(w_iidr),
+		 SBSA_GWDT_W_IIDR_ARCH_VER(w_iidr),
+		 SBSA_GWDT_W_IIDR_REV(w_iidr));
+
+	dev_info(dev, "Initialized with %ds timeout, %ds pretimeout @ %uHz\n",
+		 wdd->timeout, wdd->pretimeout, gwdt->clk);
+
+	return 0;
+}
+
+static void sbsa_gwdt_shutdown(struct platform_device *pdev)
+{
+	struct sbsa_gwdt *gwdt = platform_get_drvdata(pdev);
+
+	sbsa_gwdt_stop(&gwdt->wdd);
+}
+
+static int sbsa_gwdt_remove(struct platform_device *pdev)
+{
+	struct sbsa_gwdt *gwdt = platform_get_drvdata(pdev);
+	int ret = 0;
+
+	if (!nowayout)
+		ret = sbsa_gwdt_stop(&gwdt->wdd);
+
+	watchdog_unregister_device(&gwdt->wdd);
+
+	return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+/* Disable watchdog if it is active during suspend */
+static int sbsa_gwdt_suspend(struct device *dev)
+{
+	struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
+	struct watchdog_device *wdd = &gwdt->wdd;
+
+	spin_lock(&gwdt->lock);
+	gwdt->pm_status_store = sbsa_gwdt_cf_read(SBSA_GWDT_WCS, wdd);
+
+	if (gwdt->pm_status_store & SBSA_GWDT_WCS_EN)
+		sbsa_gwdt_stop(wdd);
+	spin_unlock(&gwdt->lock);
+
+	return 0;
+}
+
+/* Enable watchdog and configure it if necessary */
+static int sbsa_gwdt_resume(struct device *dev)
+{
+	struct sbsa_gwdt *gwdt = dev_get_drvdata(dev);
+	struct watchdog_device *wdd = &gwdt->wdd;
+
+	spin_lock(&gwdt->lock);
+	if (gwdt->pm_status_store & SBSA_GWDT_WCS_EN)
+		sbsa_gwdt_start(wdd);
+	else
+		sbsa_gwdt_stop(wdd);
+	spin_unlock(&gwdt->lock);
+
+	return 0;
+}
+#endif
+
+static const struct of_device_id sbsa_gwdt_of_match[] = {
+	{ .compatible = "arm,sbsa-gwdt", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sbsa_gwdt_of_match);
+
+static const struct dev_pm_ops sbsa_gwdt_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(sbsa_gwdt_suspend, sbsa_gwdt_resume)
+};
+
+static struct platform_driver sbsa_gwdt_driver = {
+	.driver = {
+		.name = "sbsa-gwdt",
+		.pm = &sbsa_gwdt_pm_ops,
+		.of_match_table = sbsa_gwdt_of_match,
+	},
+	.probe = sbsa_gwdt_probe,
+	.remove = sbsa_gwdt_remove,
+	.shutdown = sbsa_gwdt_shutdown,
+};
+
+module_platform_driver(sbsa_gwdt_driver);
+
+MODULE_DESCRIPTION("SBSA Generic Watchdog Driver");
+MODULE_AUTHOR("Fu Wei <fu.wei@...aro.org>");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

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