Re: [PATCH v3 2/2] watchdog: Add Spreadtrum watchdog driver

[Eric Long]

Hi Guenter,

Thanks for you commonts.

On Thu, Oct 26, 2017 at 10:23:40PM -0700, Guenter Roeck wrote:
> On 10/26/2017 07:28 PM, Eric Long wrote:
> >This patch adds the watchdog driver for Spreadtrum SC9860 platform.
> >
> >Signed-off-by: Eric Long <eric.long@xxxxxxxxxxxxxx>
> >---
> >Change since v2:
> >  - Rename all the macors, add SPRD tag at the head of the macro names.
> >  - Rename SPRD_WDT_CLK as SPRD_WTC_CNT_STEP.
> >  - Remove the code which check timeout value at the wrong place.
> >  - Add min/max timeout value limit.
> >  - Remove set WDOG_HW_RUNNING status at sprd_wdt_enable().
> >  - Add timeout/pretimeout judgment when set them.
> >  - Support WATCHDOG_NOWAYOUT status.
> >
> >Changes since v1:
> >  - Use pretimeout instead of own implementation.
> >  - Fix timeout loop when loading timeout values.
> >  - use the infrastructure to read and set "timeout-sec" property.
> >  - Add conditions when start or stop watchdog.
> >  - Change the position of enabling watchdog.
> >  - Other optimization.
> >---
> >  drivers/watchdog/Kconfig    |   8 +
> >  drivers/watchdog/Makefile   |   1 +
> >  drivers/watchdog/sprd_wdt.c | 415 ++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 424 insertions(+)
> >  create mode 100644 drivers/watchdog/sprd_wdt.c
> >
> >diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> >index c722cbf..4a77e17 100644
> >--- a/drivers/watchdog/Kconfig
> >+++ b/drivers/watchdog/Kconfig
> >@@ -787,6 +787,14 @@ config UNIPHIER_WATCHDOG
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called uniphier_wdt.
> >+config SPRD_WATCHDOG
> >+	tristate "Spreadtrum watchdog support"
> >+	depends on ARCH_SPRD || COMPILE_TEST
> >+	select WATCHDOG_CORE
> >+	help
> >+	  Say Y here to include support watchdog timer embedded
> >+	  into the Spreadtrum system.
> 
> Maybe better "supported by" instead of "embedded into". Or at least
> "embedded in".

OK, I will fix it.
 
> >+
> >  # AVR32 Architecture
> >  config AT32AP700X_WDT
> >diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> >index 56adf9f..187cca2 100644
> >--- a/drivers/watchdog/Makefile
> >+++ b/drivers/watchdog/Makefile
> >@@ -87,6 +87,7 @@ obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
> >  obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
> >  obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
> >  obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
> >+obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
> >  # AVR32 Architecture
> >  obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> >diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> >new file mode 100644
> >index 0000000..5fc3dde
> >--- /dev/null
> >+++ b/drivers/watchdog/sprd_wdt.c
> >@@ -0,0 +1,415 @@
> >+/*
> >+ * Spreadtrum watchdog driver
> >+ * Copyright (C) 2017 Spreadtrum - http://www.spreadtrum.com
> >+ *
> >+ * This program is free software; you can redistribute it and/or
> >+ * modify it under the terms of the GNU General Public License
> >+ * version 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.
> >+ */
> >+
> >+#include <linux/bitops.h>
> >+#include <linux/clk.h>
> >+#include <linux/err.h>
> >+#include <linux/interrupt.h>
> >+#include <linux/io.h>
> >+#include <linux/kernel.h>
> >+#include <linux/module.h>
> >+#include <linux/of.h>
> >+#include <linux/of_address.h>
> >+#include <linux/platform_device.h>
> >+#include <linux/watchdog.h>
> >+
> >+#define SPRD_WDT_LOAD_LOW		0x0
> >+#define SPRD_WDT_LOAD_HIGH		0x4
> >+#define SPRD_WDT_CTRL			0x8
> >+#define SPRD_WDT_INT_CLR		0xc
> >+#define SPRD_WDT_INT_RAW		0x10
> >+#define SPRD_WDT_INT_MSK		0x14
> >+#define SPRD_WDT_CNT_LOW		0x18
> >+#define SPRD_WDT_CNT_HIGH		0x1c
> >+#define SPRD_WDT_LOCK			0x20
> >+#define SPRD_WDT_IRQ_LOAD_LOW		0x2c
> >+#define SPRD_WDT_IRQ_LOAD_HIGH		0x30
> >+
> >+/* WDT_CTRL */
> >+#define SPRD_WDT_INT_EN_BIT		BIT(0)
> >+#define SPRD_WDT_CNT_EN_BIT		BIT(1)
> >+#define SPRD_WDT_NEW_VER_EN		BIT(2)
> >+#define SPRD_WDT_RST_EN_BIT		BIT(3)
> >+
> >+/* WDT_INT_CLR */
> >+#define SPRD_WDT_INT_CLEAR_BIT		BIT(0)
> >+#define SPRD_WDT_RST_CLEAR_BIT		BIT(3)
> >+
> >+/* WDT_INT_RAW */
> >+#define SPRD_WDT_INT_RAW_BIT		BIT(0)
> >+#define SPRD_WDT_RST_RAW_BIT		BIT(3)
> >+#define SPRD_WDT_LD_BUSY_BIT		BIT(4)
> >+
> >+/* 1s equale to 32768 counter steps */
> 
> equal ?
>

OK, I will fix it.

> >+#define SPRD_WDT_CNT_STEP		32768
> >+
> >+#define SPRD_WDT_UNLOCK_KEY		0xe551
> >+#define SPRD_WDT_MIN_TIMROUT		3
> 
> TIMROUT ot TIMEOUT ?
> 

OK, I will fix it.

> >+#define SPRD_WDT_MAX_TIMEOUT		60
> 
> Is that really the maximum supported timeout ? Seems a bit low.
> Shouldn't it be something like (U32_MAX / SPRD_WDT_CNT_STEP) ?
> 

It supports the max value like as U32_MAX/SPRD_WDT_CNT_STEP,
but it doesn't unnecessary to support so big value, if the system can not
response it in 60s, the watchdog could trigger timeout.

> >+
> >+#define SPRD_WDT_CNT_HIGH_VALUE		16
> 
> Maybe name it "SPRD_WDT_CNT_HIGH_SHIFT". It is not really a value,
> it is a shift.
>

Yes, you are right, _SHIFT will be better.
 
> >+#define SPRD_WDT_LOW_VALUE_MASK		GENMASK(15, 0)
> >+#define SPRD_WDT_CNT_VALUE_MAX		GENMASK(31, 0)
> 
> Does this mask serve a useful purpose ?
> 

OK, I will remove it, thanks!

> >+#define SPRD_WDT_LOAD_TIMEOUT		1000
> >+
> >+struct sprd_wdt {
> >+	void __iomem *base;
> >+	struct watchdog_device wdd;
> >+	struct clk *enable;
> >+	struct clk *rtc_enable;
> >+	unsigned int irq;
> >+};
> >+
> >+static inline struct sprd_wdt *to_sprd_wdt(struct watchdog_device *wdd)
> >+{
> >+	return container_of(wdd, struct sprd_wdt, wdd);
> >+}
> >+
> >+static inline void sprd_wdt_lock(void __iomem *addr)
> >+{
> >+	writel_relaxed(0x0, addr + SPRD_WDT_LOCK);
> >+}
> >+
> >+static inline void sprd_wdt_unlock(void __iomem *addr)
> >+{
> >+	writel_relaxed(SPRD_WDT_UNLOCK_KEY, addr + SPRD_WDT_LOCK);
> >+}
> >+
> >+static inline bool sprd_wdt_is_running(struct sprd_wdt *wdt)
> >+{
> >+	u32 val;
> >+
> >+	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
> >+	return val & SPRD_WDT_NEW_VER_EN;
> >+}
> >+
> >+static irqreturn_t sprd_wdt_isr(int irq, void *dev_id)
> >+{
> >+	struct sprd_wdt *wdt = (struct sprd_wdt *)dev_id;
> >+
> >+	sprd_wdt_unlock(wdt->base);
> >+	writel_relaxed(SPRD_WDT_INT_CLEAR_BIT, wdt->base + SPRD_WDT_INT_CLR);
> >+	sprd_wdt_lock(wdt->base);
> >+	watchdog_notify_pretimeout(&wdt->wdd);
> >+	return IRQ_HANDLED;
> >+}
> >+
> >+static u32 sprd_wdt_get_cnt_value(struct sprd_wdt *wdt)
> >+{
> >+	u32 val;
> >+
> >+	val = readl_relaxed(wdt->base + SPRD_WDT_CNT_HIGH) <<
> >+		SPRD_WDT_CNT_HIGH_VALUE;
> >+	val |= readl_relaxed(wdt->base + SPRD_WDT_CNT_LOW) &
> >+		SPRD_WDT_LOW_VALUE_MASK;
> >+
> >+	return val;
> >+}
> >+
> >+static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
> >+			       u32 pretimeout)
> >+{
> >+	u32 val, delay_cnt = 0;
> >+	u32 tmr_step = timeout * SPRD_WDT_CNT_STEP;
> >+	u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP;
> >+
> >+	sprd_wdt_unlock(wdt->base);
> >+	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_VALUE) &
> >+		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
> >+	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
> >+		       wdt->base + SPRD_WDT_LOAD_LOW);
> >+	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_VALUE) &
> >+			SPRD_WDT_LOW_VALUE_MASK,
> >+		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
> >+	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
> >+		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
> >+	sprd_wdt_lock(wdt->base);
> >+
> >+	/*
> >+	 * Waiting the load value operation done,
> >+	 * it needs two or three RTC clock cycles.
> >+	 */
> >+	do {
> >+		val = readl_relaxed(wdt->base + SPRD_WDT_INT_RAW);
> >+		if (!(val & SPRD_WDT_LD_BUSY_BIT))
> >+			break;
> >+
> >+		cpu_relax();
> >+	} while (delay_cnt++ < SPRD_WDT_LOAD_TIMEOUT);
> >+
> >+	if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
> >+		return -EBUSY;
> >+	return 0;
> >+}
> >+
> >+static int sprd_wdt_enable(struct sprd_wdt *wdt)
> >+{
> >+	u32 val;
> >+	int ret;
> >+
> >+	ret = clk_prepare_enable(wdt->enable);
> >+	if (ret)
> >+		return ret;
> >+	ret = clk_prepare_enable(wdt->rtc_enable);
> >+	if (ret)
> >+		return ret;
> >+
> >+	sprd_wdt_unlock(wdt->base);
> >+	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
> >+	val |= SPRD_WDT_NEW_VER_EN;
> >+	writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
> >+	sprd_wdt_lock(wdt->base);
> >+	return 0;
> >+}
> >+
> >+static void sprd_wdt_disable(struct sprd_wdt *wdt)
> >+{
> >+	sprd_wdt_unlock(wdt->base);
> >+	writel_relaxed(0x0, wdt->base + SPRD_WDT_CTRL);
> >+	sprd_wdt_lock(wdt->base);
> >+
> >+	clk_disable_unprepare(wdt->rtc_enable);
> >+	clk_disable_unprepare(wdt->enable);
> >+}
> >+
> >+static int sprd_wdt_start(struct watchdog_device *wdd)
> >+{
> >+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
> >+	u32 val;
> >+	int ret;
> >+
> >+	ret = sprd_wdt_load_value(wdt, wdd->timeout, wdd->pretimeout);
> >+	if (ret)
> >+		return ret;
> >+
> >+	sprd_wdt_unlock(wdt->base);
> >+	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
> >+	val |= SPRD_WDT_CNT_EN_BIT | SPRD_WDT_INT_EN_BIT | SPRD_WDT_RST_EN_BIT;
> >+	writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
> >+	sprd_wdt_lock(wdt->base);
> >+	set_bit(WDOG_HW_RUNNING, &wdd->status);
> >+
> >+	return 0;
> >+}
> >+
> >+static int sprd_wdt_stop(struct watchdog_device *wdd)
> >+{
> >+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
> >+	u32 val;
> >+
> >+	sprd_wdt_unlock(wdt->base);
> >+	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
> >+	val &= ~(SPRD_WDT_CNT_EN_BIT | SPRD_WDT_RST_EN_BIT |
> >+		SPRD_WDT_INT_EN_BIT);
> >+	writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
> >+	sprd_wdt_lock(wdt->base);
> >+	return 0;
> >+}
> >+
> >+static int sprd_wdt_set_timeout(struct watchdog_device *wdd,
> >+				u32 timeout)
> >+{
> >+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
> >+
> >+	if (timeout == wdd->timeout)
> >+		return 0;
> >+
> >+	wdd->timeout = timeout;
> >+
> >+	return sprd_wdt_load_value(wdt, timeout, wdd->pretimeout);
> >+}
> >+
> >+static int sprd_wdt_set_pretimeout(struct watchdog_device *wdd,
> >+				   u32 new_pretimeout)
> >+{
> >+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
> >+
> >+	if (new_pretimeout == wdd->pretimeout)
> >+		return 0;
> 
> This is inconsistent. pretimeout == 0 is accepted until it is set
> to a non-zero value once, then 0 is no longer accepted. pretimeout==0
> should reflect "pretimeout disabled". If that is not possible you
> need to set some non-0 default value in the probe function.
>

I understand your opinion, I will fix it.

> >+	if (new_pretimeout <= wdd->min_timeout)
> >+		return -EINVAL;
> 
> Why is pretimeout == wdd->min_timeout invalid ?
> 

OK, you are right, it should be pretimeout < min_timeout.

> >+
> >+	wdd->pretimeout = new_pretimeout;
> >+
> >+	return sprd_wdt_load_value(wdt, wdd->timeout, new_pretimeout);
> >+}
> >+
> >+static u32 sprd_wdt_get_timeleft(struct watchdog_device *wdd)
> >+{
> >+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
> >+	u32 val;
> >+
> >+	val = sprd_wdt_get_cnt_value(wdt);
> >+	val = val / SPRD_WDT_CNT_STEP;
> >+
> >+	return val;
> >+}
> >+
> >+static const struct watchdog_ops sprd_wdt_ops = {
> >+	.owner = THIS_MODULE,
> >+	.start = sprd_wdt_start,
> >+	.stop = sprd_wdt_stop,
> >+	.set_timeout = sprd_wdt_set_timeout,
> >+	.set_pretimeout = sprd_wdt_set_pretimeout,
> >+	.get_timeleft = sprd_wdt_get_timeleft,
> 
> Just wondering - no heartbeat function ? Having to load the timer
> values for each heartbeat is expensive.
>

Unfortunately, this watchdog has not RELOAD register.
 
> >+};
> >+
> >+static const struct watchdog_info sprd_wdt_info = {
> >+	.options = WDIOF_SETTIMEOUT |
> >+		   WDIOF_PRETIMEOUT |
> >+		   WDIOF_MAGICCLOSE |
> >+		   WDIOF_KEEPALIVEPING,
> >+	.identity = "Spreadtrum Watchdog Timer",
> >+};
> >+
> >+static int sprd_wdt_probe(struct platform_device *pdev)
> >+{
> >+	struct resource *wdt_res;
> >+	struct sprd_wdt *wdt;
> >+	int ret;
> >+
> >+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> >+	if (!wdt)
> >+		return -ENOMEM;
> >+
> >+	wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >+	if (!wdt_res) {
> >+		dev_err(&pdev->dev, "failed to memory resource\n");
> >+		return -ENOMEM;
> >+	}
> 
> Unnecessary error check and message. devm_ioremap_resource()
> returns an error if res is NULL.
>

OK, I will fix it.
 
> >+
> >+	wdt->base = devm_ioremap_resource(&pdev->dev, wdt_res);
> >+	if (IS_ERR(wdt->base))
> 
> Move the error message to here.
> 
> >+		return PTR_ERR(wdt->base);
> >+
> >+	wdt->enable = devm_clk_get(&pdev->dev, "enable");
> >+	if (IS_ERR(wdt->enable)) {
> >+		dev_err(&pdev->dev, "can't get the enable clock\n");
> >+		return PTR_ERR(wdt->enable);
> >+	}
> >+
> >+	wdt->rtc_enable = devm_clk_get(&pdev->dev, "rtc_enable");
> >+	if (IS_ERR(wdt->rtc_enable)) {
> >+		dev_err(&pdev->dev, "can't get the rtc enable clock\n");
> >+		return PTR_ERR(wdt->rtc_enable);
> >+	}
> >+
> >+	wdt->irq = platform_get_irq(pdev, 0);
> >+	if (wdt->irq < 0) {
> >+		dev_err(&pdev->dev, "failed to get IRQ resource\n");
> >+		return wdt->irq;
> >+	}
> >+
> >+	ret = devm_request_irq(&pdev->dev, wdt->irq, sprd_wdt_isr,
> >+			       IRQF_NO_SUSPEND, "sprd-wdt", (void *)wdt);
> >+	if (ret) {
> >+		dev_err(&pdev->dev, "failed to register irq\n");
> >+		return ret;
> >+	}
> >+
> >+	wdt->wdd.info = &sprd_wdt_info;
> >+	wdt->wdd.ops = &sprd_wdt_ops;
> >+	wdt->wdd.parent = &pdev->dev;
> >+	wdt->wdd.min_timeout = SPRD_WDT_MIN_TIMROUT;
> >+	wdt->wdd.max_timeout = SPRD_WDT_MAX_TIMEOUT;
> >+
> You might want to set wdt->wdd.timeout to a default value.
>

OK, I will set a default timeout value in case of no timeout-sec in device-tree.
 
> >+	ret = sprd_wdt_enable(wdt);
> >+	if (ret) {
> >+		dev_err(&pdev->dev, "failed to enable wdt\n");
> >+		return ret;
> >+	}
> >+
> 
> This needs a matching sprd_wdt_disable() call in the remove function.
> Best way to handle this would be to add devm_add_action() here.
> 

If add devm_add_action(), it will be called in the remove function,
but this is not our expect, if someone remove this module, we want it just timeout.

> >+	watchdog_set_nowayout(&wdt->wdd, WATCHDOG_NOWAYOUT);
> >+	watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
> >+
> >+	ret = watchdog_register_device(&wdt->wdd);
> 
> Unfortunately this doesn't work. It leaves interrupts enabled
> after the watchdog device is removed in sprd_wdt_remove(),
> but the driver will be gone. I would suggest to use
> devm_watchdog_register_device() and reorder calls to request
> the interrupt after registering the watchdog device. Then you
> can drop the remove function entirely.
> 

Yes, you are right, I understand your opinion, and it is very important,
devm_watchdog_register_device() is better. Thanks.

> >+	if (ret) {
> >+		sprd_wdt_disable(wdt);
> >+		dev_err(&pdev->dev, "failed to register watchdog\n");
> >+		return ret;
> >+	}
> >+	platform_set_drvdata(pdev, wdt);
> >+
> >+	return 0;
> >+}
> >+
> >+static int sprd_wdt_remove(struct platform_device *pdev)
> >+{
> >+	struct sprd_wdt *wdt = platform_get_drvdata(pdev);
> >+
> >+	watchdog_unregister_device(&wdt->wdd);
> >+
> >+	if (sprd_wdt_is_running(wdt))
> >+		dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
> >+	return 0;
> >+}
> >+
> >+static int __maybe_unused sprd_wdt_pm_suspend(struct device *dev)
> >+{
> >+	struct watchdog_device *wdd = dev_get_drvdata(dev);
> >+	struct sprd_wdt *wdt = dev_get_drvdata(dev);
> >+
> >+	if (watchdog_active(wdd)) {
> >+		sprd_wdt_stop(&wdt->wdd);
> >+		sprd_wdt_disable(wdt);
> 
> Are you sure you only want to disable the clocks if the watchdog was active ?
> That seems to be a bit inconsistent.
> 

This watchdog is in always on power domain, if system suspend, it needs to
disable it, or it will timeout.

> >+	}
> >+
> >+	return 0;
> >+}
> >+
> >+static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
> >+{
> >+	struct watchdog_device *wdd = dev_get_drvdata(dev);
> >+	struct sprd_wdt *wdt = dev_get_drvdata(dev);
> >+	int ret;
> >+
> >+	if (watchdog_active(wdd)) {
> >+		ret = sprd_wdt_enable(wdt);
> >+		if (ret)
> >+			return ret;
> >+		ret = sprd_wdt_start(&wdt->wdd);
> >+		if (ret) {
> >+			sprd_wdt_disable(wdt);
> >+			return ret;
> >+		}
> 
> This can leave the system in an inconsistent state. Sometimes the wdt may be
> disabled, sometimes not.
>

If watchdog enable failed, it means there is something wrong in this system.
 
> >+	}
> >+
> >+	return 0;
> >+}
> >+
> >+static const struct dev_pm_ops sprd_wdt_pm_ops = {
> >+	SET_SYSTEM_SLEEP_PM_OPS(sprd_wdt_pm_suspend,
> >+				sprd_wdt_pm_resume)
> >+};
> >+
> >+static const struct of_device_id sprd_wdt_match_table[] = {
> >+	{ .compatible = "sprd,sp9860-wdt", },
> >+	{},
> >+};
> >+MODULE_DEVICE_TABLE(of, sprd_wdt_match_table);
> >+
> >+static struct platform_driver sprd_watchdog_driver = {
> >+	.probe	= sprd_wdt_probe,
> >+	.remove	= sprd_wdt_remove,
> >+	.driver	= {
> >+		.name = "sprd-wdt",
> >+		.of_match_table = sprd_wdt_match_table,
> >+		.pm = &sprd_wdt_pm_ops,
> >+	},
> >+};
> >+module_platform_driver(sprd_watchdog_driver);
> >+
> >+MODULE_AUTHOR("Eric Long <eric.long@xxxxxxxxxxxxxx>");
> >+MODULE_DESCRIPTION("Spreadtrum Watchdog Timer Controller Driver");
> >+MODULE_LICENSE("GPL v2");
> >
>