diff mbox series

[v2,2/2] watchdog: Add Toshiba Visconti watchdog driver

Message ID 20200918221337.257157-3-nobuhiro1.iwamatsu@toshiba.co.jp (mailing list archive)
State Superseded
Headers show
Series Add WDT driver for Toshiba Visconti ARM SoC | expand

Commit Message

Nobuhiro Iwamatsu Sept. 18, 2020, 10:13 p.m. UTC 
Add the watchdog driver for Toshiba Visconti series.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
---
 drivers/watchdog/Kconfig        |   8 ++
 drivers/watchdog/Makefile       |   1 +
 drivers/watchdog/visconti_wdt.c | 195 ++++++++++++++++++++++++++++++++
 3 files changed, 204 insertions(+)
 create mode 100644 drivers/watchdog/visconti_wdt.c

Comments

Guenter Roeck Sept. 19, 2020, 2:28 p.m. UTC | #1 
On 9/18/20 3:13 PM, Nobuhiro Iwamatsu wrote:
> Add the watchdog driver for Toshiba Visconti series.
> 
> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> ---
>  drivers/watchdog/Kconfig        |   8 ++
>  drivers/watchdog/Makefile       |   1 +
>  drivers/watchdog/visconti_wdt.c | 195 ++++++++++++++++++++++++++++++++
>  3 files changed, 204 insertions(+)
>  create mode 100644 drivers/watchdog/visconti_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index ab7aad5a1e69..0cb078ce5e9d 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1004,6 +1004,14 @@ config PM8916_WATCHDOG
>  	  Say Y here to include support watchdog timer embedded into the
>  	  pm8916 module.
>  
> +config VISCONTI_WATCHDOG
> +	tristate "Toshiba Visconti series watchdog support"
> +	depends on ARCH_VISCONTI || COMPILE_TEST
> +	select WATCHDOG_CORE
> +	help
> +	  Say Y here to include support for the watchdog timer in Toshiba
> +	  Visconti SoCs.
> +
>  # X86 (i386 + ia64 + x86_64) Architecture
>  
>  config ACQUIRE_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 97bed1d3d97c..a7747e76fd29 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -95,6 +95,7 @@ obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o
>  obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
>  obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
>  obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
> +obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
>  
>  # X86 (i386 + ia64 + x86_64) Architecture
>  obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
> diff --git a/drivers/watchdog/visconti_wdt.c b/drivers/watchdog/visconti_wdt.c
> new file mode 100644
> index 000000000000..cb8a88e4737e
> --- /dev/null
> +++ b/drivers/watchdog/visconti_wdt.c
> @@ -0,0 +1,195 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2020 TOSHIBA CORPORATION
> + * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
> + * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +#define WDT_CNT			0x00
> +#define WDT_MIN			0x04
> +#define WDT_MAX			0x08
> +#define WDT_CTL			0x0c
> +#define WDT_CMD			0x10
> +#define WDT_CMD_CLEAR		0x4352
> +#define WDT_CMD_START_STOP	0x5354
> +#define WDT_DIV			0x30
> +
> +#define VISCONTI_WDT_FREQ	2000000 /* 2MHz */
> +#define WDT_DEFAULT_TIMEOUT	10U /* in seconds */
> +
> +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) ")");
> +
Line split is unnecessary (limit is now 100 comlumns)

> +struct visconti_wdt_priv {
> +	struct watchdog_device wdev;
> +	void __iomem *base;
> +	u32 div;
> +};
> +
> +static int visconti_wdt_start(struct watchdog_device *wdev)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
> +
> +	writel(priv->div, priv->base + WDT_DIV);
> +	writel(0, priv->base + WDT_MIN);
> +	writel(timeout, priv->base + WDT_MAX);
> +	writel(0, priv->base + WDT_CTL);
> +	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
> +
> +	return 0;
> +}
> +
> +static int visconti_wdt_stop(struct watchdog_device *wdev)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	writel(1, priv->base + WDT_CTL);
> +	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
> +
> +	return 0;
> +}
> +
> +static int visconti_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
> +
> +	return 0;
> +}
> +
> +static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
> +	u32 cnt = readl(priv->base + WDT_CNT);
> +
> +	if (timeout > cnt)
> +		timeout -= cnt;
> +	else
> +		return 0;

This is a bit awkward. Please consider

	if (timeout <= cnt)
		return 0;
	timeout -= cnt;

> +
> +	return timeout / VISCONTI_WDT_FREQ;
> +}
> +
> +static int visconti_wdt_set_timeout(struct watchdog_device *wdev,
> +				    unsigned int timeout)

Another unnecessary line split

> +{
> +	u32 val;
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	wdev->timeout = timeout;
> +	val = wdev->timeout * VISCONTI_WDT_FREQ;
> +
> +	/* Clear counter before setting timeout because WDT expires */
> +	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
> +	writel(val, priv->base + WDT_MAX);
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info visconti_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> +	.identity = "Visconti Watchdog",
> +};
> +
> +static const struct watchdog_ops visconti_wdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= visconti_wdt_start,
> +	.stop		= visconti_wdt_stop,
> +	.ping		= visconti_wdt_ping,
> +	.get_timeleft	= visconti_wdt_get_timeleft,
> +	.set_timeout	= visconti_wdt_set_timeout,
> +};
> +
> +static int visconti_wdt_probe(struct platform_device *pdev)
> +{
> +	struct watchdog_device *wdev;
> +	struct visconti_wdt_priv *priv;
> +	struct device *dev = &pdev->dev;
> +	struct clk *clk;
> +	int ret;
> +	unsigned long clk_freq;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(priv->base))
> +		return PTR_ERR(priv->base);
> +
> +	clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(clk))
> +		return dev_err_probe(dev, PTR_ERR(clk),
> +			"Could not get clock\n");

another one.

> +
> +	ret = clk_prepare_enable(clk);
> +	if (ret) {
> +		dev_err(dev, "Could not enable clock\n");
> +		return ret;
> +	}
> +
> +	clk_freq = clk_get_rate(clk);
> +	if (!clk_freq) {
> +		clk_disable_unprepare(clk);
> +		dev_err(dev, "Could not get clock rate\n");
> +		return -EINVAL;
> +	}
> +
> +	priv->div = clk_freq / VISCONTI_WDT_FREQ;
> +
> +	/* Initialize struct watchdog_device. */
> +	wdev = &priv->wdev;
> +	wdev->info = &visconti_wdt_info;
> +	wdev->ops = &visconti_wdt_ops;
> +	wdev->parent = dev;
> +	wdev->min_timeout = 1;
> +	wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
> +	wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
> +
> +	watchdog_set_drvdata(wdev, priv);
> +	watchdog_set_nowayout(wdev, nowayout);
> +	watchdog_stop_on_unregister(wdev);
> +
> +	/* This overrides the default timeout only if DT configuration was found */
> +	ret = watchdog_init_timeout(wdev, 0, dev);
> +	if (ret)
> +		dev_warn(dev, "Specified timeout value invalid, using default\n");
> +
> +	return devm_watchdog_register_device(dev, wdev);
> +}
> +
> +static const struct of_device_id visconti_wdt_of_match[] = {
> +	{ .compatible = "toshiba,visconti-wdt", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
> +
> +static struct platform_driver visconti_wdt_driver = {
> +	.driver = {
> +			.name = "visconti_wdt",
> +			.of_match_table = visconti_wdt_of_match,
> +		},
> +	.probe = visconti_wdt_probe,
> +};
> +module_platform_driver(visconti_wdt_driver);
> +
> +MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
> +MODULE_AUTHOR("TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION");
> +MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");
> +MODULE_LICENSE("GPL v2");
>
Nobuhiro Iwamatsu Sept. 20, 2020, 5:10 a.m. UTC | #2 
Hi,

Thanks for your review.

On Sat, Sep 19, 2020 at 07:28:42AM -0700, Guenter Roeck wrote:
> On 9/18/20 3:13 PM, Nobuhiro Iwamatsu wrote:
> > Add the watchdog driver for Toshiba Visconti series.
> > 
> > Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> > ---
> >  drivers/watchdog/Kconfig        |   8 ++
> >  drivers/watchdog/Makefile       |   1 +
> >  drivers/watchdog/visconti_wdt.c | 195 ++++++++++++++++++++++++++++++++
> >  3 files changed, 204 insertions(+)
> >  create mode 100644 drivers/watchdog/visconti_wdt.c
> > 

<snip>

> > diff --git a/drivers/watchdog/visconti_wdt.c b/drivers/watchdog/visconti_wdt.c
> > new file mode 100644
> > index 000000000000..cb8a88e4737e
> > --- /dev/null
> > +++ b/drivers/watchdog/visconti_wdt.c
> > @@ -0,0 +1,195 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2020 TOSHIBA CORPORATION
> > + * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
> > + * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/watchdog.h>
> > +
> > +#define WDT_CNT			0x00
> > +#define WDT_MIN			0x04
> > +#define WDT_MAX			0x08
> > +#define WDT_CTL			0x0c
> > +#define WDT_CMD			0x10
> > +#define WDT_CMD_CLEAR		0x4352
> > +#define WDT_CMD_START_STOP	0x5354
> > +#define WDT_DIV			0x30
> > +
> > +#define VISCONTI_WDT_FREQ	2000000 /* 2MHz */
> > +#define WDT_DEFAULT_TIMEOUT	10U /* in seconds */
> > +
> > +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) ")");
> > +
> Line split is unnecessary (limit is now 100 comlumns)
> 

OK, I will fix this.

> > +struct visconti_wdt_priv {
> > +	struct watchdog_device wdev;
> > +	void __iomem *base;
> > +	u32 div;
> > +};
> > +
> > +static int visconti_wdt_start(struct watchdog_device *wdev)
> > +{
> > +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
> > +
> > +	writel(priv->div, priv->base + WDT_DIV);
> > +	writel(0, priv->base + WDT_MIN);
> > +	writel(timeout, priv->base + WDT_MAX);
> > +	writel(0, priv->base + WDT_CTL);
> > +	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
> > +
> > +	return 0;
> > +}
> > +
> > +static int visconti_wdt_stop(struct watchdog_device *wdev)
> > +{
> > +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > +	writel(1, priv->base + WDT_CTL);
> > +	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
> > +
> > +	return 0;
> > +}
> > +
> > +static int visconti_wdt_ping(struct watchdog_device *wdd)
> > +{
> > +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
> > +
> > +	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
> > +
> > +	return 0;
> > +}
> > +
> > +static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
> > +{
> > +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
> > +	u32 cnt = readl(priv->base + WDT_CNT);
> > +
> > +	if (timeout > cnt)
> > +		timeout -= cnt;
> > +	else
> > +		return 0;
> 
> This is a bit awkward. Please consider
> 
> 	if (timeout <= cnt)
> 		return 0;
> 	timeout -= cnt;
> 

I see. I will apply your suggestion, thanks.

> > +
> > +	return timeout / VISCONTI_WDT_FREQ;
> > +}
> > +
> > +static int visconti_wdt_set_timeout(struct watchdog_device *wdev,
> > +				    unsigned int timeout)
> 
> Another unnecessary line split

OK, I will fix this.

> 
> > +{
> > +	u32 val;
> > +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > +	wdev->timeout = timeout;
> > +	val = wdev->timeout * VISCONTI_WDT_FREQ;
> > +
> > +	/* Clear counter before setting timeout because WDT expires */
> > +	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
> > +	writel(val, priv->base + WDT_MAX);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct watchdog_info visconti_wdt_info = {
> > +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> > +	.identity = "Visconti Watchdog",
> > +};
> > +
> > +static const struct watchdog_ops visconti_wdt_ops = {
> > +	.owner		= THIS_MODULE,
> > +	.start		= visconti_wdt_start,
> > +	.stop		= visconti_wdt_stop,
> > +	.ping		= visconti_wdt_ping,
> > +	.get_timeleft	= visconti_wdt_get_timeleft,
> > +	.set_timeout	= visconti_wdt_set_timeout,
> > +};
> > +
> > +static int visconti_wdt_probe(struct platform_device *pdev)
> > +{
> > +	struct watchdog_device *wdev;
> > +	struct visconti_wdt_priv *priv;
> > +	struct device *dev = &pdev->dev;
> > +	struct clk *clk;
> > +	int ret;
> > +	unsigned long clk_freq;
> > +
> > +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> > +	priv->base = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(priv->base))
> > +		return PTR_ERR(priv->base);
> > +
> > +	clk = devm_clk_get(dev, NULL);
> > +	if (IS_ERR(clk))
> > +		return dev_err_probe(dev, PTR_ERR(clk),
> > +			"Could not get clock\n");
> 
> another one.

OK, I will fix this.

> 
> > +
> > +	ret = clk_prepare_enable(clk);
> > +	if (ret) {
> > +		dev_err(dev, "Could not enable clock\n");
> > +		return ret;
> > +	}

<snip>

Best regards,
  Nobuhiro
diff mbox series

Patch

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index ab7aad5a1e69..0cb078ce5e9d 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1004,6 +1004,14 @@  config PM8916_WATCHDOG
 	  Say Y here to include support watchdog timer embedded into the
 	  pm8916 module.
 
+config VISCONTI_WATCHDOG
+	tristate "Toshiba Visconti series watchdog support"
+	depends on ARCH_VISCONTI || COMPILE_TEST
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support for the watchdog timer in Toshiba
+	  Visconti SoCs.
+
 # X86 (i386 + ia64 + x86_64) Architecture
 
 config ACQUIRE_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 97bed1d3d97c..a7747e76fd29 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -95,6 +95,7 @@  obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o
 obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
 obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
 obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
+obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
 
 # X86 (i386 + ia64 + x86_64) Architecture
 obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
diff --git a/drivers/watchdog/visconti_wdt.c b/drivers/watchdog/visconti_wdt.c
new file mode 100644
index 000000000000..cb8a88e4737e
--- /dev/null
+++ b/drivers/watchdog/visconti_wdt.c
@@ -0,0 +1,195 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020 TOSHIBA CORPORATION
+ * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
+ * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+ */
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#define WDT_CNT			0x00
+#define WDT_MIN			0x04
+#define WDT_MAX			0x08
+#define WDT_CTL			0x0c
+#define WDT_CMD			0x10
+#define WDT_CMD_CLEAR		0x4352
+#define WDT_CMD_START_STOP	0x5354
+#define WDT_DIV			0x30
+
+#define VISCONTI_WDT_FREQ	2000000 /* 2MHz */
+#define WDT_DEFAULT_TIMEOUT	10U /* in seconds */
+
+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) ")");
+
+struct visconti_wdt_priv {
+	struct watchdog_device wdev;
+	void __iomem *base;
+	u32 div;
+};
+
+static int visconti_wdt_start(struct watchdog_device *wdev)
+{
+	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
+
+	writel(priv->div, priv->base + WDT_DIV);
+	writel(0, priv->base + WDT_MIN);
+	writel(timeout, priv->base + WDT_MAX);
+	writel(0, priv->base + WDT_CTL);
+	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
+
+	return 0;
+}
+
+static int visconti_wdt_stop(struct watchdog_device *wdev)
+{
+	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	writel(1, priv->base + WDT_CTL);
+	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
+
+	return 0;
+}
+
+static int visconti_wdt_ping(struct watchdog_device *wdd)
+{
+	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
+
+	return 0;
+}
+
+static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
+{
+	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
+	u32 cnt = readl(priv->base + WDT_CNT);
+
+	if (timeout > cnt)
+		timeout -= cnt;
+	else
+		return 0;
+
+	return timeout / VISCONTI_WDT_FREQ;
+}
+
+static int visconti_wdt_set_timeout(struct watchdog_device *wdev,
+				    unsigned int timeout)
+{
+	u32 val;
+	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	wdev->timeout = timeout;
+	val = wdev->timeout * VISCONTI_WDT_FREQ;
+
+	/* Clear counter before setting timeout because WDT expires */
+	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
+	writel(val, priv->base + WDT_MAX);
+
+	return 0;
+}
+
+static const struct watchdog_info visconti_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+	.identity = "Visconti Watchdog",
+};
+
+static const struct watchdog_ops visconti_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= visconti_wdt_start,
+	.stop		= visconti_wdt_stop,
+	.ping		= visconti_wdt_ping,
+	.get_timeleft	= visconti_wdt_get_timeleft,
+	.set_timeout	= visconti_wdt_set_timeout,
+};
+
+static int visconti_wdt_probe(struct platform_device *pdev)
+{
+	struct watchdog_device *wdev;
+	struct visconti_wdt_priv *priv;
+	struct device *dev = &pdev->dev;
+	struct clk *clk;
+	int ret;
+	unsigned long clk_freq;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+			"Could not get clock\n");
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(dev, "Could not enable clock\n");
+		return ret;
+	}
+
+	clk_freq = clk_get_rate(clk);
+	if (!clk_freq) {
+		clk_disable_unprepare(clk);
+		dev_err(dev, "Could not get clock rate\n");
+		return -EINVAL;
+	}
+
+	priv->div = clk_freq / VISCONTI_WDT_FREQ;
+
+	/* Initialize struct watchdog_device. */
+	wdev = &priv->wdev;
+	wdev->info = &visconti_wdt_info;
+	wdev->ops = &visconti_wdt_ops;
+	wdev->parent = dev;
+	wdev->min_timeout = 1;
+	wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
+	wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
+
+	watchdog_set_drvdata(wdev, priv);
+	watchdog_set_nowayout(wdev, nowayout);
+	watchdog_stop_on_unregister(wdev);
+
+	/* This overrides the default timeout only if DT configuration was found */
+	ret = watchdog_init_timeout(wdev, 0, dev);
+	if (ret)
+		dev_warn(dev, "Specified timeout value invalid, using default\n");
+
+	return devm_watchdog_register_device(dev, wdev);
+}
+
+static const struct of_device_id visconti_wdt_of_match[] = {
+	{ .compatible = "toshiba,visconti-wdt", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
+
+static struct platform_driver visconti_wdt_driver = {
+	.driver = {
+			.name = "visconti_wdt",
+			.of_match_table = visconti_wdt_of_match,
+		},
+	.probe = visconti_wdt_probe,
+};
+module_platform_driver(visconti_wdt_driver);
+
+MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
+MODULE_AUTHOR("TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION");
+MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");
+MODULE_LICENSE("GPL v2");