[PATCH v6 0/2] add a new driver to support SAMA5D4 watchdog timer

[PATCH v6 0/2] add a new driver to support SAMA5D4 watchdog timer

[Wenyou Yang]

Hello,

Because the watchdog WDT_MR register can be written more than once,
its work mechanism is different from the at91sam9260 watchdog driver.
Open the device file to enable the watchdog hardware, close to disable it,
and ping it from the user space directly to keep it alive.

Changes from v5.0
 1./ Add the commas back in after last member for structure variables,
     sama5d4_wdt_info and sama5d4_wdt_ops.

Changes from v4.0
 1./ Fix interrupt register function flags argument.
 2./ Replace the tabs after #define with spaces.

Changes from v3.0
 1./ Change the driver name to 'sama5d4_wdt' for more acceptable.
 2./ Change the prefix of function name and struct name
     from 'atmel_' to 'sama5d4_', and others.

Changes from v2.0
 1./ Use a specific driver name, at91_sama5d4_wdt.c.
 2./ Remove '-' at the end of macro name and unnecessary check.
 3./ Use alphabetic order for include files.


Wenyou Yang (2):
  drivers: watchdog: add a driver to support SAMA5D4 watchdog timer
  Documentation: dt: binding: atmel-sama5d4-wdt: for SAMA5D4 watchdog
    driver

 .../bindings/watchdog/atmel-sama5d4-wdt.txt        |   35 +++
 drivers/watchdog/Kconfig                           |    9 +
 drivers/watchdog/Makefile                          |    1 +
 drivers/watchdog/at91sam9_wdt.h                    |    2 +
 drivers/watchdog/sama5d4_wdt.c                     |  280 ++++++++++++++++++++
 5 files changed, 327 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt
 create mode 100644 drivers/watchdog/sama5d4_wdt.c

-- 
1.7.9.5

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[PATCH v6 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Wenyou Yang]

>From SAMA5D4, the watchdog timer is upgrated with a new feature,
which is describled as in the datasheet, "WDT_MR can be written
until a LOCKMR command is issued in WDT_CR".
That is to say, as long as the bootstrap and u-boot don't issue
a LOCKMR command, WDT_MR can be written more than once in the driver.

So the SAMA5D4 watchdog driver's implementation is different from
the at91sam9260 watchdog driver implemented in file at91sam9_wdt.c.
The user application open the device file to enable the watchdog timer
hardware, and close to disable it, and set the watchdog timer timeout
by seting WDV and WDD fields of WDT_MR register, and ping the watchdog
by issuing WDRSTT command to WDT_CR register with hard-coded key.

Signed-off-by: Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
---
 drivers/watchdog/Kconfig        |    9 ++
 drivers/watchdog/Makefile       |    1 +
 drivers/watchdog/at91sam9_wdt.h |    2 +
 drivers/watchdog/sama5d4_wdt.c  |  280 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 292 insertions(+)
 create mode 100644 drivers/watchdog/sama5d4_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e5e7c55..47ad39a 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -167,6 +167,15 @@ config AT91SAM9X_WATCHDOG
 	  Watchdog timer embedded into AT91SAM9X and AT91CAP9 chips. This will
 	  reboot your system when the timeout is reached.
 
+config SAMA5D4_WATCHDOG
+	tristate "Atmel SAMA5D4 Watchdog Timer"
+	depends on ARCH_AT91
+	select WATCHDOG_CORE
+	help
+	  Atmel SAMA5D4 watchdog timer is embedded into SAMA5D4 chips.
+	  Its Watchdog Timer Mode Register can be written more than once.
+	  This will reboot your system when the timeout is reached.
+
 config CADENCE_WATCHDOG
 	tristate "Cadence Watchdog Timer"
 	select WATCHDOG_CORE
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 5c19294..f24b820 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_IXP4XX_WATCHDOG) += ixp4xx_wdt.o
 obj-$(CONFIG_KS8695_WATCHDOG) += ks8695_wdt.o
 obj-$(CONFIG_S3C2410_WATCHDOG) += s3c2410_wdt.o
 obj-$(CONFIG_SA1100_WATCHDOG) += sa1100_wdt.o
+obj-$(CONFIG_SAMA5D4_WATCHDOG) += sama5d4_wdt.o
 obj-$(CONFIG_DW_WATCHDOG) += dw_wdt.o
 obj-$(CONFIG_EP93XX_WATCHDOG) += ep93xx_wdt.o
 obj-$(CONFIG_PNX4008_WATCHDOG) += pnx4008_wdt.o
diff --git a/drivers/watchdog/at91sam9_wdt.h b/drivers/watchdog/at91sam9_wdt.h
index c6fbb2e6..b79a83b 100644
--- a/drivers/watchdog/at91sam9_wdt.h
+++ b/drivers/watchdog/at91sam9_wdt.h
@@ -22,11 +22,13 @@
 
 #define AT91_WDT_MR		0x04			/* Watchdog Mode Register */
 #define		AT91_WDT_WDV		(0xfff << 0)		/* Counter Value */
+#define			AT91_WDT_SET_WDV(x)	((x) & AT91_WDT_WDV)
 #define		AT91_WDT_WDFIEN		(1     << 12)		/* Fault Interrupt Enable */
 #define		AT91_WDT_WDRSTEN	(1     << 13)		/* Reset Processor */
 #define		AT91_WDT_WDRPROC	(1     << 14)		/* Timer Restart */
 #define		AT91_WDT_WDDIS		(1     << 15)		/* Watchdog Disable */
 #define		AT91_WDT_WDD		(0xfff << 16)		/* Delta Value */
+#define			AT91_WDT_SET_WDD(x)	(((x) << 16) & AT91_WDT_WDD)
 #define		AT91_WDT_WDDBGHLT	(1     << 28)		/* Debug Halt */
 #define		AT91_WDT_WDIDLEHLT	(1     << 29)		/* Idle Halt */
 
diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
new file mode 100644
index 0000000..a49634c
--- /dev/null
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -0,0 +1,280 @@
+/*
+ * Driver for Atmel SAMA5D4 Watchdog Timer
+ *
+ * Copyright (C) 2015 Atmel Corporation
+ *
+ * Licensed under GPLv2.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+
+#include "at91sam9_wdt.h"
+
+/* minimum and maximum watchdog timeout, in seconds */
+#define MIN_WDT_TIMEOUT		1
+#define MAX_WDT_TIMEOUT		16
+#define WDT_DEFAULT_TIMEOUT	MAX_WDT_TIMEOUT
+
+#define WDT_SEC2TICKS(s)	((s) ? (((s) << 8) - 1) : 0)
+
+struct sama5d4_wdt {
+	struct watchdog_device	wdd;
+	void __iomem		*reg_base;
+	u32	config;
+};
+
+static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+module_param(wdt_timeout, int, 0);
+MODULE_PARM_DESC(wdt_timeout,
+	"Watchdog timeout in seconds. (default = "
+	__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
+
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout,
+	"Watchdog cannot be stopped once started (default="
+	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+#define wdt_read(wdt, field) \
+	readl_relaxed((wdt)->reg_base + (field))
+
+#define wdt_write(wtd, field, val) \
+	writel_relaxed((val), (wdt)->reg_base + (field))
+
+static int sama5d4_wdt_start(struct watchdog_device *wdd)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+	u32 reg;
+
+	reg = wdt_read(wdt, AT91_WDT_MR);
+	reg &= ~AT91_WDT_WDDIS;
+	wdt_write(wdt, AT91_WDT_MR, reg);
+
+	return 0;
+}
+
+static int sama5d4_wdt_stop(struct watchdog_device *wdd)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+	u32 reg;
+
+	reg = wdt_read(wdt, AT91_WDT_MR);
+	reg |= AT91_WDT_WDDIS;
+	wdt_write(wdt, AT91_WDT_MR, reg);
+
+	return 0;
+}
+
+static int sama5d4_wdt_ping(struct watchdog_device *wdd)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
+
+	return 0;
+}
+
+static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
+				 unsigned int timeout)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+	u32 value = WDT_SEC2TICKS(timeout);
+	u32 reg;
+
+	reg = wdt_read(wdt, AT91_WDT_MR);
+	reg &= ~AT91_WDT_WDV;
+	reg &= ~AT91_WDT_WDD;
+	reg |= AT91_WDT_SET_WDV(value);
+	reg |= AT91_WDT_SET_WDD(value);
+	wdt_write(wdt, AT91_WDT_MR, reg);
+
+	wdd->timeout = timeout;
+
+	return 0;
+}
+
+static const struct watchdog_info sama5d4_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+	.identity = "Atmel SAMA5D4 Watchdog",
+};
+
+static struct watchdog_ops sama5d4_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = sama5d4_wdt_start,
+	.stop = sama5d4_wdt_stop,
+	.ping = sama5d4_wdt_ping,
+	.set_timeout = sama5d4_wdt_set_timeout,
+};
+
+static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
+{
+	struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
+
+	if (wdt_read(wdt, AT91_WDT_SR)) {
+		pr_crit("Atmel Watchdog Software Reset\n");
+		emergency_restart();
+		pr_crit("Reboot didn't succeed\n");
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
+{
+	const char *tmp;
+
+	wdt->config = AT91_WDT_WDDIS;
+
+	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
+	    !strcmp(tmp, "software"))
+		wdt->config |= AT91_WDT_WDFIEN;
+	else
+		wdt->config |= AT91_WDT_WDRSTEN;
+
+	if (of_property_read_bool(np, "atmel,idle-halt"))
+		wdt->config |= AT91_WDT_WDIDLEHLT;
+
+	if (of_property_read_bool(np, "atmel,dbg-halt"))
+		wdt->config |= AT91_WDT_WDDBGHLT;
+
+	return 0;
+}
+
+static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
+{
+	struct watchdog_device *wdd = &wdt->wdd;
+	u32 value = WDT_SEC2TICKS(wdd->timeout);
+	u32 reg;
+
+	/*
+	 * Because the fields WDV and WDD must not be modified when the WDDIS
+	 * bit is set, so clear the WDDIS bit before writing the WDT_MR.
+	 */
+	reg = wdt_read(wdt, AT91_WDT_MR);
+	reg &= ~AT91_WDT_WDDIS;
+	wdt_write(wdt, AT91_WDT_MR, reg);
+
+	reg = wdt->config;
+	reg |= AT91_WDT_SET_WDD(value);
+	reg |= AT91_WDT_SET_WDV(value);
+
+	wdt_write(wdt, AT91_WDT_MR, reg);
+
+	return 0;
+}
+
+static int sama5d4_wdt_probe(struct platform_device *pdev)
+{
+	struct watchdog_device *wdd;
+	struct sama5d4_wdt *wdt;
+	struct resource *res;
+	void __iomem *regs;
+	u32 irq = 0;
+	int ret;
+
+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdd = &wdt->wdd;
+	wdd->timeout = wdt_timeout;
+	wdd->info = &sama5d4_wdt_info;
+	wdd->ops = &sama5d4_wdt_ops;
+	wdd->min_timeout = MIN_WDT_TIMEOUT;
+	wdd->max_timeout = MAX_WDT_TIMEOUT;
+
+	watchdog_set_drvdata(wdd, wdt);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	wdt->reg_base = regs;
+
+	if (pdev->dev.of_node) {
+		irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
+		if (!irq)
+			dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
+
+		ret = of_sama5d4_wdt_init(pdev->dev.of_node, wdt);
+		if (ret)
+			return ret;
+	}
+
+	if ((wdt->config & AT91_WDT_WDFIEN) && irq) {
+		ret = devm_request_irq(&pdev->dev, irq, sama5d4_wdt_irq_handler,
+				       IRQF_SHARED | IRQF_IRQPOLL |
+				       IRQF_NO_SUSPEND, pdev->name, pdev);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"cannot register interrupt handler\n");
+			return ret;
+		}
+	}
+
+	ret = watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to set timeout value\n");
+		return ret;
+	}
+
+	ret = sama5d4_wdt_init(wdt);
+	if (ret)
+		return ret;
+
+	watchdog_set_nowayout(wdd, nowayout);
+
+	ret = watchdog_register_device(wdd);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register watchdog device\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, wdt);
+
+	dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
+		 wdt_timeout, nowayout);
+
+	return 0;
+}
+
+static int sama5d4_wdt_remove(struct platform_device *pdev)
+{
+	struct sama5d4_wdt *wdt = platform_get_drvdata(pdev);
+
+	sama5d4_wdt_stop(&wdt->wdd);
+
+	watchdog_unregister_device(&wdt->wdd);
+
+	return 0;
+}
+
+static const struct of_device_id sama5d4_wdt_of_match[] = {
+	{ .compatible = "atmel,sama5d4-wdt", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
+
+static struct platform_driver sama5d4_wdt_driver = {
+	.probe		= sama5d4_wdt_probe,
+	.remove		= sama5d4_wdt_remove,
+	.driver		= {
+		.name	= "sama5d4_wdt",
+		.of_match_table = sama5d4_wdt_of_match,
+	}
+};
+module_platform_driver(sama5d4_wdt_driver);
+
+MODULE_AUTHOR("Atmel Corporation");
+MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5

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Re: [PATCH v6 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Guenter Roeck]

On 08/06/2015 03:16 AM, Wenyou Yang wrote:
>>From SAMA5D4, the watchdog timer is upgrated with a new feature,
> which is describled as in the datasheet, "WDT_MR can be written
> until a LOCKMR command is issued in WDT_CR".
> That is to say, as long as the bootstrap and u-boot don't issue
> a LOCKMR command, WDT_MR can be written more than once in the driver.
>
> So the SAMA5D4 watchdog driver's implementation is different from
> the at91sam9260 watchdog driver implemented in file at91sam9_wdt.c.
> The user application open the device file to enable the watchdog timer
> hardware, and close to disable it, and set the watchdog timer timeout
> by seting WDV and WDD fields of WDT_MR register, and ping the watchdog
> by issuing WDRSTT command to WDT_CR register with hard-coded key.
>
> Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

RE: [PATCH v6 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Yang, Wenyou]

> -----Original Message-----
> From: Guenter Roeck [mailto:linux@roeck-us.net]
> Sent: 2015年8月7日 23:26
> To: Yang, Wenyou; wim@iguana.be; robh+dt@kernel.org; pawel.moll@arm.com;
> mark.rutland@arm.com; ijc+devicetree@hellion.org.uk; galak@codeaurora.org
> Cc: sylvain.rochet@finsecur.com; Ferre, Nicolas; boris.brezillon@free-
> electrons.com; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> watchdog@vger.kernel.org
> Subject: Re: [PATCH v6 1/2] drivers: watchdog: add a driver to support SAMA5D4
> watchdog timer
> 
> On 08/06/2015 03:16 AM, Wenyou Yang wrote:
> >>From SAMA5D4, the watchdog timer is upgrated with a new feature,
> > which is describled as in the datasheet, "WDT_MR can be written until
> > a LOCKMR command is issued in WDT_CR".
> > That is to say, as long as the bootstrap and u-boot don't issue a
> > LOCKMR command, WDT_MR can be written more than once in the driver.
> >
> > So the SAMA5D4 watchdog driver's implementation is different from the
> > at91sam9260 watchdog driver implemented in file at91sam9_wdt.c.
> > The user application open the device file to enable the watchdog timer
> > hardware, and close to disable it, and set the watchdog timer timeout
> > by seting WDV and WDD fields of WDT_MR register, and ping the watchdog
> > by issuing WDRSTT command to WDT_CR register with hard-coded key.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
> 
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Hi Vim,

Can this patch series be merged? Could you please?

Best Regards,
Wenyou Yang

Re: [PATCH v6 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Guenter Roeck]

On 08/27/2015 06:30 PM, Yang, Wenyou wrote:
>
>
>> -----Original Message-----
>> From: Guenter Roeck [mailto:linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org]
>> Sent: 2015年8月7日 23:26
>> To: Yang, Wenyou; wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org; robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org; pawel.moll@arm.com;
>> mark.rutland-5wv7dgnIgG8@public.gmane.org; ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org; galak@codeaurora.org
>> Cc: sylvain.rochet-ETtyaVkrhkNWk0Htik3J/w@public.gmane.org; Ferre, Nicolas; boris.brezillon@free-
>> electrons.com; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-kernel-u79uwXL29TasMV2rI37PzA@public.gmane.orgorg; linux-
>> watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> Subject: Re: [PATCH v6 1/2] drivers: watchdog: add a driver to support SAMA5D4
>> watchdog timer
>>
>> On 08/06/2015 03:16 AM, Wenyou Yang wrote:
>>> >From SAMA5D4, the watchdog timer is upgrated with a new feature,
>>> which is describled as in the datasheet, "WDT_MR can be written until
>>> a LOCKMR command is issued in WDT_CR".
>>> That is to say, as long as the bootstrap and u-boot don't issue a
>>> LOCKMR command, WDT_MR can be written more than once in the driver.
>>>
>>> So the SAMA5D4 watchdog driver's implementation is different from the
>>> at91sam9260 watchdog driver implemented in file at91sam9_wdt.c.
>>> The user application open the device file to enable the watchdog timer
>>> hardware, and close to disable it, and set the watchdog timer timeout
>>> by seting WDV and WDD fields of WDT_MR register, and ping the watchdog
>>> by issuing WDRSTT command to WDT_CR register with hard-coded key.
>>>
>>> Signed-off-by: Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
>>
>> Reviewed-by: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
>
> Hi Vim,
>
> Can this patch series be merged? Could you please?
>
It is included in the pull request I sent to Wim last week.

Guenter


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[PATCH v6 2/2] Documentation: dt: binding: atmel-sama5d4-wdt: for SAMA5D4 watchdog driver

[Wenyou Yang]

The compatible "atmel,sama5d4-wdt" supports the SAMA5D4 watchdog driver
and the watchdog's WDT_MR register can be written more than once.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
---
 .../bindings/watchdog/atmel-sama5d4-wdt.txt        |   35 ++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt

diff --git a/Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt b/Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt
new file mode 100644
index 0000000..f7cc7c0
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt
@@ -0,0 +1,35 @@
+* Atmel SAMA5D4 Watchdog Timer (WDT) Controller
+
+Required properties:
+- compatible: "atmel,sama5d4-wdt"
+- reg: base physical address and length of memory mapped region.
+
+Optional properties:
+- timeout-sec: watchdog timeout value (in seconds).
+- interrupts: interrupt number to the CPU.
+- atmel,watchdog-type: should be "hardware" or "software".
+	"hardware": enable watchdog fault reset. A watchdog fault triggers
+		    watchdog reset.
+	"software": enable watchdog fault interrupt. A watchdog fault asserts
+		    watchdog interrupt.
+- atmel,idle-halt: present if you want to stop the watchdog when the CPU is
+		   in idle state.
+	CAUTION: This property should be used with care, it actually makes the
+	watchdog not counting when the CPU is in idle state, therefore the
+	watchdog reset time depends on mean CPU usage and will not reset at all
+	if the CPU stop working while it is in idle state, which is probably
+	not what you want.
+- atmel,dbg-halt: present if you want to stop the watchdog when the CPU is
+		  in debug state.
+
+Example:
+	watchdog@fc068640 {
+		compatible = "atmel,sama5d4-wdt";
+		reg = <0xfc068640 0x10>;
+		interrupts = <4 IRQ_TYPE_LEVEL_HIGH 5>;
+		timeout-sec = <10>;
+		atmel,watchdog-type = "hardware";
+		atmel,dbg-halt;
+		atmel,idle-halt;
+		status = "okay";
+	};
-- 
1.7.9.5

Re: [PATCH v6 2/2] Documentation: dt: binding: atmel-sama5d4-wdt: for SAMA5D4 watchdog driver

[Guenter Roeck]

On 08/06/2015 03:17 AM, Wenyou Yang wrote:
> The compatible "atmel,sama5d4-wdt" supports the SAMA5D4 watchdog driver
> and the watchdog's WDT_MR register can be written more than once.
>
> Signed-off-by: Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>

Reviewed-by: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>

> ---
>   .../bindings/watchdog/atmel-sama5d4-wdt.txt        |   35 ++++++++++++++++++++
>   1 file changed, 35 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt
>
> diff --git a/Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt b/Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt
> new file mode 100644
> index 0000000..f7cc7c0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt
> @@ -0,0 +1,35 @@
> +* Atmel SAMA5D4 Watchdog Timer (WDT) Controller
> +
> +Required properties:
> +- compatible: "atmel,sama5d4-wdt"
> +- reg: base physical address and length of memory mapped region.
> +
> +Optional properties:
> +- timeout-sec: watchdog timeout value (in seconds).
> +- interrupts: interrupt number to the CPU.
> +- atmel,watchdog-type: should be "hardware" or "software".
> +	"hardware": enable watchdog fault reset. A watchdog fault triggers
> +		    watchdog reset.
> +	"software": enable watchdog fault interrupt. A watchdog fault asserts
> +		    watchdog interrupt.
> +- atmel,idle-halt: present if you want to stop the watchdog when the CPU is
> +		   in idle state.
> +	CAUTION: This property should be used with care, it actually makes the
> +	watchdog not counting when the CPU is in idle state, therefore the
> +	watchdog reset time depends on mean CPU usage and will not reset at all
> +	if the CPU stop working while it is in idle state, which is probably
> +	not what you want.
> +- atmel,dbg-halt: present if you want to stop the watchdog when the CPU is
> +		  in debug state.
> +
> +Example:
> +	watchdog@fc068640 {
> +		compatible = "atmel,sama5d4-wdt";
> +		reg = <0xfc068640 0x10>;
> +		interrupts = <4 IRQ_TYPE_LEVEL_HIGH 5>;
> +		timeout-sec = <10>;
> +		atmel,watchdog-type = "hardware";
> +		atmel,dbg-halt;
> +		atmel,idle-halt;
> +		status = "okay";
> +	};
>

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