diff mbox series

[1/2] watchdog: uniphier: add UniPhier watchdog driver

Message ID 1495607692-657-2-git-send-email-hayashibara.keiji@socionext.com
State New
Headers show
Series [1/2] watchdog: uniphier: add UniPhier watchdog driver | expand

Commit Message

Keiji Hayashibara May 24, 2017, 6:34 a.m. UTC 
Add a watchdog driver for Socionext UniPhier series SoC.
Note that the timeout value for this device must be a power
of 2 because of the specification.

Signed-off-by: Keiji Hayashibara <hayashibara.keiji@socionext.com>

---
 .../devicetree/bindings/watchdog/uniphier-wdt.txt  |  20 ++
 Documentation/watchdog/watchdog-parameters.txt     |   6 +
 drivers/watchdog/Kconfig                           |  11 +
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/uniphier_wdt.c                    | 273 +++++++++++++++++++++
 5 files changed, 311 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt
 create mode 100644 drivers/watchdog/uniphier_wdt.c

-- 
2.7.4

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Comments

Guenter Roeck May 24, 2017, 1:45 p.m. UTC | #1 
On 05/23/2017 11:34 PM, Keiji Hayashibara wrote:
> Add a watchdog driver for Socionext UniPhier series SoC.

> Note that the timeout value for this device must be a power

> of 2 because of the specification.

> 

> Signed-off-by: Keiji Hayashibara <hayashibara.keiji@socionext.com>

> ---

>   .../devicetree/bindings/watchdog/uniphier-wdt.txt  |  20 ++

>   Documentation/watchdog/watchdog-parameters.txt     |   6 +

>   drivers/watchdog/Kconfig                           |  11 +

>   drivers/watchdog/Makefile                          |   1 +

>   drivers/watchdog/uniphier_wdt.c                    | 273 +++++++++++++++++++++

>   5 files changed, 311 insertions(+)

>   create mode 100644 Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt

>   create mode 100644 drivers/watchdog/uniphier_wdt.c

> 

> diff --git a/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt

> new file mode 100644

> index 0000000..a59d1ba

> --- /dev/null

> +++ b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt

> @@ -0,0 +1,20 @@

> +UniPhier watchdog timer controller

> +

> +This UniPhier watchdog timer controller must be under sysctrl compatible node.

> +

> +Required properties:

> +- compatible: should be "socionext,uniphier-wdt"

> +

> +Example:

> +

> +	sysctrl@61840000 {

> +		compatible = "socionext,uniphier-ld11-sysctrl",

> +			     "simple-mfd", "syscon";

> +		reg = <0x61840000 0x4000>;

> +

> +		sys_wdt: watchdog {

> +			compatible = "socionext,uniphier-wdt";

> +		}

> +

> +		other nodes ...

> +	};


Bindings should be in a separate patch.

> diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt > index 4f7d86d..6f9d7b4 100644

> --- a/Documentation/watchdog/watchdog-parameters.txt

> +++ b/Documentation/watchdog/watchdog-parameters.txt

> @@ -369,6 +369,12 @@ timeout: Watchdog timeout in seconds. (0<timeout<N, default=60)

>   nowayout: Watchdog cannot be stopped once started

>   	(default=kernel config parameter)

>   -------------------------------------------------

> +uniphier_wdt:

> +timeout: Watchdog timeout in power of two seconds.

> +	(1 <= timeout <= 128, default=64)

> +nowayout: Watchdog cannot be stopped once started

> +	(default=kernel config parameter)

> +-------------------------------------------------

>   w83627hf_wdt:

>   wdt_io: w83627hf/thf WDT io port (default 0x2E)

>   timeout: Watchdog timeout in seconds. 1 <= timeout <= 255, default=60.

> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig

> index 52a70ee..2a9d9a6 100644

> --- a/drivers/watchdog/Kconfig

> +++ b/drivers/watchdog/Kconfig

> @@ -744,6 +744,17 @@ config ZX2967_WATCHDOG

>   	  To compile this driver as a module, choose M here: the

>   	  module will be called zx2967_wdt.

>   

> +config UNIPHIER_WATCHDOG

> +	tristate "UniPhier watchdog support"

> +	depends on ARCH_UNIPHIER || COMPILE_TEST

> +	select WATCHDOG_CORE

> +	help

> +	  Say Y here to include support watchdog timer embedded

> +	  into the UniPhier system.

> +

> +	  To compile this driver as a module, choose M here: the

> +	  module will be called uniphier_wdt.

> +

>   # AVR32 Architecture

>   

>   config AT32AP700X_WDT

> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile

> index a2126e2..0928dac 100644

> --- a/drivers/watchdog/Makefile

> +++ b/drivers/watchdog/Makefile

> @@ -84,6 +84,7 @@ obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o

>   obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o

>   obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o

>   obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o

> +obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o

>   

>   # AVR32 Architecture

>   obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

> diff --git a/drivers/watchdog/uniphier_wdt.c b/drivers/watchdog/uniphier_wdt.c

> new file mode 100644

> index 0000000..80ad2a3

> --- /dev/null

> +++ b/drivers/watchdog/uniphier_wdt.c

> @@ -0,0 +1,273 @@

> +/*

> + * Watchdog driver for the UniPhier watchdog timer

> + *

> + * (c) Copyright 2014 Panasonic Corporation

> + * (c) Copyright 2016 Socionext Inc.

> + * All rights reserved.

> + *

> + * This program is free software; you can redistribute it and/or modify

> + * it under the terms of the GNU General Public License as published by

> + * the Free Software Foundation; either version 2 of the License, or

> + * (at your option) any later version.

> + *

> + * 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/delay.h>

> +#include <linux/module.h>

> +#include <linux/mfd/syscon.h>

> +#include <linux/of.h>

> +#include <linux/platform_device.h>

> +#include <linux/regmap.h>

> +#include <linux/watchdog.h>

> +

> +/* WDT timer setting register */

> +#define WDTTIMSET			0x3004

> +#define   WDTTIMSET_PERIOD_MASK		(0xf << 0)

> +#define   WDTTIMSET_PERIOD_1_SEC	(0x3 << 0)

> +#define   WDTTIMSET_PERIOD_2_SEC	(0x4 << 0)

> +#define   WDTTIMSET_PERIOD_4_SEC	(0x5 << 0)

> +#define   WDTTIMSET_PERIOD_8_SEC	(0x6 << 0)

> +#define   WDTTIMSET_PERIOD_16_SEC	(0x7 << 0)

> +#define   WDTTIMSET_PERIOD_32_SEC	(0x8 << 0)

> +#define   WDTTIMSET_PERIOD_64_SEC	(0x9 << 0)

> +#define   WDTTIMSET_PERIOD_128_SEC	(0xa << 0)

> +

> +/* WDT reset selection register */

> +#define WDTRSTSEL			0x3008

> +#define   WDTRSTSEL_RSTSEL_MASK		(0x3 << 0)

> +#define   WDTRSTSEL_RSTSEL_BOTH		(0x0 << 0)

> +#define   WDTRSTSEL_RSTSEL_IRQ_ONLY	(0x2 << 0)

> +

> +/* WDT control register */

> +#define WDTCTRL				0x300c

> +#define   WDTCTRL_STATUS		BIT(8)

> +#define   WDTCTRL_CLEAR			BIT(1)

> +#define   WDTCTRL_ENABLE		BIT(0)

> +


Should include bitops.h.

> +#define SEC_TO_WDTTIMSET_PRD(sec) \

> +		(ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)

> +

> +#define WDTST_TIMEOUT			1000 /* usec */

> +

> +#define WDT_DEFAULT_TIMEOUT		64   /* Default is 64 seconds */

> +#define WDT_PERIOD_MIN			1

> +#define WDT_PERIOD_MAX			128

> +

> +static unsigned int timeout = WDT_DEFAULT_TIMEOUT;

> +static bool nowayout = WATCHDOG_NOWAYOUT;

> +

> +struct uniphier_wdt_dev {

> +	struct watchdog_device wdt_dev;

> +	struct regmap	*regmap;

> +};

> +

> +/*

> + * UniPhier Watchdog operations

> + */

> +static int uniphier_watchdog_ping(struct watchdog_device *w)

> +{

> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);

> +

> +	/* Clear counter */

> +	return regmap_write(wdev->regmap, WDTCTRL,

> +			    WDTCTRL_CLEAR | WDTCTRL_ENABLE);

> +}

> +

> +static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)

> +{

> +	int ret;

> +

> +	/* Setup period */

> +	ret = regmap_write(regmap, WDTTIMSET,

> +			   SEC_TO_WDTTIMSET_PRD(sec));

> +	if (ret)

> +		return ret;

> +

> +	/* Enable and clear watchdog */

> +	return regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);

> +}

> +

> +static int __uniphier_watchdog_stop(struct regmap *regmap)

> +{

> +	/* Disable and stop watchdog */

> +	return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);

> +}

> +

> +static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)

> +{

> +	unsigned int val;

> +	int ret;

> +

> +	ret = __uniphier_watchdog_stop(regmap);

> +	if (ret)

> +		return ret;

> +

> +	ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,

> +				       !(val & WDTCTRL_STATUS),

> +				       0, WDTST_TIMEOUT);

> +	if (ret)

> +		return ret;

> +

> +	return __uniphier_watchdog_start(regmap, sec);

> +}

> +

> +static int uniphier_watchdog_start(struct watchdog_device *w)

> +{

> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);

> +	unsigned int tmp_timeout;

> +

> +	tmp_timeout = roundup_pow_of_two(w->timeout);

> +

> +	return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);

> +}

> +

> +static int uniphier_watchdog_stop(struct watchdog_device *w)

> +{

> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);

> +

> +	return __uniphier_watchdog_stop(wdev->regmap);

> +}

> +

> +static int uniphier_watchdog_set_timeout(struct watchdog_device *w,

> +					 unsigned int t)

> +{

> +	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);

> +	unsigned int tmp_timeout;

> +	int ret;

> +

> +	tmp_timeout = roundup_pow_of_two(t);

> +	if (tmp_timeout == w->timeout)

> +		return 0;

> +

> +	if (watchdog_active(w)) {

> +		ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);

> +		if (ret)

> +			return ret;

> +	}

> +

> +	w->timeout = tmp_timeout;

> +

> +	return 0;

> +}

> +

> +/*

> + * Kernel Interfaces

> + */

> +static const struct watchdog_info uniphier_wdt_info = {

> +	.identity	= "uniphier-wdt",

> +	.options	= WDIOF_SETTIMEOUT |

> +			  WDIOF_KEEPALIVEPING |

> +			  WDIOF_MAGICCLOSE |

> +			  WDIOF_OVERHEAT,

> +};

> +

> +static const struct watchdog_ops uniphier_wdt_ops = {

> +	.owner		= THIS_MODULE,

> +	.start		= uniphier_watchdog_start,

> +	.stop		= uniphier_watchdog_stop,

> +	.ping		= uniphier_watchdog_ping,

> +	.set_timeout	= uniphier_watchdog_set_timeout,

> +	.restart	= NULL,


What is this about ? It is unnecessary to set a static variable to NULL.

> +};

> +

> +static int uniphier_wdt_probe(struct platform_device *pdev)

> +{

> +	struct device *dev = &pdev->dev;

> +	struct uniphier_wdt_dev *wdev;

> +	struct regmap *regmap;

> +	struct device_node *parent;

> +	int ret;

> +

> +	wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);

> +	if (!wdev)

> +		return -ENOMEM;

> +

> +	platform_set_drvdata(pdev, wdev);

> +

> +	parent = of_get_parent(dev->of_node); /* parent should be syscon node */

> +	regmap = syscon_node_to_regmap(parent);

> +	of_node_put(parent);

> +	if (IS_ERR(regmap))

> +		return PTR_ERR(regmap);

> +

> +	wdev->regmap = regmap;

> +	wdev->wdt_dev.info = &uniphier_wdt_info;

> +	wdev->wdt_dev.ops = &uniphier_wdt_ops;

> +	wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;

> +	wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;

> +	wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;

> +	wdev->wdt_dev.parent = dev;

> +

> +	watchdog_init_timeout(&wdev->wdt_dev, timeout, dev);

> +	watchdog_set_nowayout(&wdev->wdt_dev, nowayout);

> +	watchdog_set_restart_priority(&wdev->wdt_dev, 128);


This does not make sense without a restart handler function.

> +

> +	watchdog_set_drvdata(&wdev->wdt_dev, wdev);

> +

> +	uniphier_watchdog_stop(&wdev->wdt_dev);

> +	ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);

> +	if (ret)

> +		return ret;

> +

> +	ret = watchdog_register_device(&wdev->wdt_dev);


You can use devm_watchdog_register_device().

> +	if (ret)

> +		return ret;

> +

> +	dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",

> +		 wdev->wdt_dev.timeout, nowayout);

> +

> +	return 0;

> +}

> +

> +static void uniphier_wdt_shutdown(struct platform_device *pdev)

> +{

> +	struct uniphier_wdt_dev *wdev = platform_get_drvdata(pdev);

> +

> +	if (watchdog_active(&wdev->wdt_dev))

> +		uniphier_watchdog_stop(&wdev->wdt_dev);


Can you use WDOG_STOP_ON_REBOOT instead ?

> +}

> +

> +static int uniphier_wdt_remove(struct platform_device *pdev)

> +{

> +	struct uniphier_wdt_dev *wdev = platform_get_drvdata(pdev);

> +

> +	watchdog_unregister_device(&wdev->wdt_dev);

> +

> +	return 0;

> +}

> +

> +static const struct of_device_id uniphier_wdt_dt_ids[] = {

> +	{ .compatible = "socionext,uniphier-wdt" },

> +	{ /* sentinel */ }

> +};

> +MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);

> +

> +static struct platform_driver uniphier_wdt_driver = {

> +	.probe		= uniphier_wdt_probe,

> +	.remove		= uniphier_wdt_remove,

> +	.shutdown	= uniphier_wdt_shutdown,

> +	.driver		= {

> +		.name		= "uniphier-wdt",

> +		.of_match_table	= uniphier_wdt_dt_ids,

> +	},

> +};

> +

> +module_platform_driver(uniphier_wdt_driver);

> +

> +module_param(timeout, uint, 0000);

> +MODULE_PARM_DESC(timeout,

> +	"Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="

> +				__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");

> +

> +module_param(nowayout, bool, 0000);

> +MODULE_PARM_DESC(nowayout,

> +	"Watchdog cannot be stopped once started (default="

> +				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

> +

> +MODULE_AUTHOR("Socionext Inc.");

> +MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");

> +MODULE_LICENSE("GPL v2");

> 


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Masahiro Yamada May 25, 2017, 5:45 a.m. UTC | #2 
Hi Hayashibara-san


> a/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt

> b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt

> new file mode 100644

> index 0000000..a59d1ba

> --- /dev/null

> +++ b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt

> @@ -0,0 +1,20 @@

> +UniPhier watchdog timer controller

> +

> +This UniPhier watchdog timer controller must be under sysctrl compatible

> node.

> +

> +Required properties:

> +- compatible: should be "socionext,uniphier-wdt"

> +

> +Example:

> +

> +	sysctrl@61840000 {

> +		compatible = "socionext,uniphier-ld11-sysctrl",

> +			     "simple-mfd", "syscon";

> +		reg = <0x61840000 0x4000>;

> +

> +		sys_wdt: watchdog {

> +			compatible = "socionext,uniphier-wdt";

> +		}

> +

> +		other nodes ...

> +	};



Next time, please include
devicetree@vger.kernel.org
(and Rob) in your CC list for binding review.

I think scripts/get_maintainer.pl will do it correctly for you.





> +#include <linux/delay.h>


Is this used?


Thanks.
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt
new file mode 100644
index 0000000..a59d1ba
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/uniphier-wdt.txt
@@ -0,0 +1,20 @@ 
+UniPhier watchdog timer controller
+
+This UniPhier watchdog timer controller must be under sysctrl compatible node.
+
+Required properties:
+- compatible: should be "socionext,uniphier-wdt"
+
+Example:
+
+	sysctrl@61840000 {
+		compatible = "socionext,uniphier-ld11-sysctrl",
+			     "simple-mfd", "syscon";
+		reg = <0x61840000 0x4000>;
+
+		sys_wdt: watchdog {
+			compatible = "socionext,uniphier-wdt";
+		}
+
+		other nodes ...
+	};
diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt
index 4f7d86d..6f9d7b4 100644
--- a/Documentation/watchdog/watchdog-parameters.txt
+++ b/Documentation/watchdog/watchdog-parameters.txt
@@ -369,6 +369,12 @@  timeout: Watchdog timeout in seconds. (0<timeout<N, default=60)
 nowayout: Watchdog cannot be stopped once started
 	(default=kernel config parameter)
 -------------------------------------------------
+uniphier_wdt:
+timeout: Watchdog timeout in power of two seconds.
+	(1 <= timeout <= 128, default=64)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
 w83627hf_wdt:
 wdt_io: w83627hf/thf WDT io port (default 0x2E)
 timeout: Watchdog timeout in seconds. 1 <= timeout <= 255, default=60.
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 52a70ee..2a9d9a6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -744,6 +744,17 @@  config ZX2967_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called zx2967_wdt.
 
+config UNIPHIER_WATCHDOG
+	tristate "UniPhier watchdog support"
+	depends on ARCH_UNIPHIER || COMPILE_TEST
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support watchdog timer embedded
+	  into the UniPhier system.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called uniphier_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a2126e2..0928dac 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -84,6 +84,7 @@  obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
 obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
 obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
 obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
+obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/uniphier_wdt.c b/drivers/watchdog/uniphier_wdt.c
new file mode 100644
index 0000000..80ad2a3
--- /dev/null
+++ b/drivers/watchdog/uniphier_wdt.c
@@ -0,0 +1,273 @@ 
+/*
+ * Watchdog driver for the UniPhier watchdog timer
+ *
+ * (c) Copyright 2014 Panasonic Corporation
+ * (c) Copyright 2016 Socionext Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/delay.h>
+#include <linux/module.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/watchdog.h>
+
+/* WDT timer setting register */
+#define WDTTIMSET			0x3004
+#define   WDTTIMSET_PERIOD_MASK		(0xf << 0)
+#define   WDTTIMSET_PERIOD_1_SEC	(0x3 << 0)
+#define   WDTTIMSET_PERIOD_2_SEC	(0x4 << 0)
+#define   WDTTIMSET_PERIOD_4_SEC	(0x5 << 0)
+#define   WDTTIMSET_PERIOD_8_SEC	(0x6 << 0)
+#define   WDTTIMSET_PERIOD_16_SEC	(0x7 << 0)
+#define   WDTTIMSET_PERIOD_32_SEC	(0x8 << 0)
+#define   WDTTIMSET_PERIOD_64_SEC	(0x9 << 0)
+#define   WDTTIMSET_PERIOD_128_SEC	(0xa << 0)
+
+/* WDT reset selection register */
+#define WDTRSTSEL			0x3008
+#define   WDTRSTSEL_RSTSEL_MASK		(0x3 << 0)
+#define   WDTRSTSEL_RSTSEL_BOTH		(0x0 << 0)
+#define   WDTRSTSEL_RSTSEL_IRQ_ONLY	(0x2 << 0)
+
+/* WDT control register */
+#define WDTCTRL				0x300c
+#define   WDTCTRL_STATUS		BIT(8)
+#define   WDTCTRL_CLEAR			BIT(1)
+#define   WDTCTRL_ENABLE		BIT(0)
+
+#define SEC_TO_WDTTIMSET_PRD(sec) \
+		(ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)
+
+#define WDTST_TIMEOUT			1000 /* usec */
+
+#define WDT_DEFAULT_TIMEOUT		64   /* Default is 64 seconds */
+#define WDT_PERIOD_MIN			1
+#define WDT_PERIOD_MAX			128
+
+static unsigned int timeout = WDT_DEFAULT_TIMEOUT;
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+struct uniphier_wdt_dev {
+	struct watchdog_device wdt_dev;
+	struct regmap	*regmap;
+};
+
+/*
+ * UniPhier Watchdog operations
+ */
+static int uniphier_watchdog_ping(struct watchdog_device *w)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+
+	/* Clear counter */
+	return regmap_write(wdev->regmap, WDTCTRL,
+			    WDTCTRL_CLEAR | WDTCTRL_ENABLE);
+}
+
+static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)
+{
+	int ret;
+
+	/* Setup period */
+	ret = regmap_write(regmap, WDTTIMSET,
+			   SEC_TO_WDTTIMSET_PRD(sec));
+	if (ret)
+		return ret;
+
+	/* Enable and clear watchdog */
+	return regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);
+}
+
+static int __uniphier_watchdog_stop(struct regmap *regmap)
+{
+	/* Disable and stop watchdog */
+	return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);
+}
+
+static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)
+{
+	unsigned int val;
+	int ret;
+
+	ret = __uniphier_watchdog_stop(regmap);
+	if (ret)
+		return ret;
+
+	ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
+				       !(val & WDTCTRL_STATUS),
+				       0, WDTST_TIMEOUT);
+	if (ret)
+		return ret;
+
+	return __uniphier_watchdog_start(regmap, sec);
+}
+
+static int uniphier_watchdog_start(struct watchdog_device *w)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+	unsigned int tmp_timeout;
+
+	tmp_timeout = roundup_pow_of_two(w->timeout);
+
+	return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);
+}
+
+static int uniphier_watchdog_stop(struct watchdog_device *w)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+
+	return __uniphier_watchdog_stop(wdev->regmap);
+}
+
+static int uniphier_watchdog_set_timeout(struct watchdog_device *w,
+					 unsigned int t)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+	unsigned int tmp_timeout;
+	int ret;
+
+	tmp_timeout = roundup_pow_of_two(t);
+	if (tmp_timeout == w->timeout)
+		return 0;
+
+	if (watchdog_active(w)) {
+		ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);
+		if (ret)
+			return ret;
+	}
+
+	w->timeout = tmp_timeout;
+
+	return 0;
+}
+
+/*
+ * Kernel Interfaces
+ */
+static const struct watchdog_info uniphier_wdt_info = {
+	.identity	= "uniphier-wdt",
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE |
+			  WDIOF_OVERHEAT,
+};
+
+static const struct watchdog_ops uniphier_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= uniphier_watchdog_start,
+	.stop		= uniphier_watchdog_stop,
+	.ping		= uniphier_watchdog_ping,
+	.set_timeout	= uniphier_watchdog_set_timeout,
+	.restart	= NULL,
+};
+
+static int uniphier_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct uniphier_wdt_dev *wdev;
+	struct regmap *regmap;
+	struct device_node *parent;
+	int ret;
+
+	wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
+	if (!wdev)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, wdev);
+
+	parent = of_get_parent(dev->of_node); /* parent should be syscon node */
+	regmap = syscon_node_to_regmap(parent);
+	of_node_put(parent);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	wdev->regmap = regmap;
+	wdev->wdt_dev.info = &uniphier_wdt_info;
+	wdev->wdt_dev.ops = &uniphier_wdt_ops;
+	wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;
+	wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;
+	wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;
+	wdev->wdt_dev.parent = dev;
+
+	watchdog_init_timeout(&wdev->wdt_dev, timeout, dev);
+	watchdog_set_nowayout(&wdev->wdt_dev, nowayout);
+	watchdog_set_restart_priority(&wdev->wdt_dev, 128);
+
+	watchdog_set_drvdata(&wdev->wdt_dev, wdev);
+
+	uniphier_watchdog_stop(&wdev->wdt_dev);
+	ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);
+	if (ret)
+		return ret;
+
+	ret = watchdog_register_device(&wdev->wdt_dev);
+	if (ret)
+		return ret;
+
+	dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",
+		 wdev->wdt_dev.timeout, nowayout);
+
+	return 0;
+}
+
+static void uniphier_wdt_shutdown(struct platform_device *pdev)
+{
+	struct uniphier_wdt_dev *wdev = platform_get_drvdata(pdev);
+
+	if (watchdog_active(&wdev->wdt_dev))
+		uniphier_watchdog_stop(&wdev->wdt_dev);
+}
+
+static int uniphier_wdt_remove(struct platform_device *pdev)
+{
+	struct uniphier_wdt_dev *wdev = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&wdev->wdt_dev);
+
+	return 0;
+}
+
+static const struct of_device_id uniphier_wdt_dt_ids[] = {
+	{ .compatible = "socionext,uniphier-wdt" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);
+
+static struct platform_driver uniphier_wdt_driver = {
+	.probe		= uniphier_wdt_probe,
+	.remove		= uniphier_wdt_remove,
+	.shutdown	= uniphier_wdt_shutdown,
+	.driver		= {
+		.name		= "uniphier-wdt",
+		.of_match_table	= uniphier_wdt_dt_ids,
+	},
+};
+
+module_platform_driver(uniphier_wdt_driver);
+
+module_param(timeout, uint, 0000);
+MODULE_PARM_DESC(timeout,
+	"Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="
+				__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
+
+module_param(nowayout, bool, 0000);
+MODULE_PARM_DESC(nowayout,
+	"Watchdog cannot be stopped once started (default="
+				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+MODULE_AUTHOR("Socionext Inc.");
+MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");
+MODULE_LICENSE("GPL v2");