[PATCH v3 0/2] add a new driver to support SAMA5D4 watchdog timer

[PATCH v3 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.

Thank for Guenter's review, the version 2.0 changes are listed as below.

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/at91_sama5d4_wdt.c                |  279 ++++++++++++++++++++
 drivers/watchdog/at91sam9_wdt.h                    |    2 +
 5 files changed, 326 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/atmel-sama5d4-wdt.txt
 create mode 100644 drivers/watchdog/at91_sama5d4_wdt.c

-- 
1.7.9.5

[PATCH v3 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@atmel.com>
---
 drivers/watchdog/Kconfig            |    9 ++
 drivers/watchdog/Makefile           |    1 +
 drivers/watchdog/at91_sama5d4_wdt.c |  279 +++++++++++++++++++++++++++++++++++
 drivers/watchdog/at91sam9_wdt.h     |    2 +
 4 files changed, 291 insertions(+)
 create mode 100644 drivers/watchdog/at91_sama5d4_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e5e7c55..4ce8346 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -152,6 +152,15 @@ config ARM_SP805_WATCHDOG
 	  ARM Primecell SP805 Watchdog timer. This will reboot your system when
 	  the timeout is reached.
 
+config AT91_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 AT91RM9200_WATCHDOG
 	tristate "AT91RM9200 watchdog"
 	depends on SOC_AT91RM9200 && MFD_SYSCON
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 5c19294..c57569c 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_AT91_SAMA5D4_WATCHDOG) += at91_sama5d4_wdt.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/at91_sama5d4_wdt.c b/drivers/watchdog/at91_sama5d4_wdt.c
new file mode 100644
index 0000000..f2e1995
--- /dev/null
+++ b/drivers/watchdog/at91_sama5d4_wdt.c
@@ -0,0 +1,279 @@
+/*
+ * 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 atmel_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 wdt_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 atmel_wdt_start(struct watchdog_device *wdd)
+{
+	struct atmel_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 atmel_wdt_stop(struct watchdog_device *wdd)
+{
+	struct atmel_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 atmel_wdt_ping(struct watchdog_device *wdd)
+{
+	struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
+
+	return 0;
+}
+
+static int atmel_wdt_set_timeout(struct watchdog_device *wdd,
+				 unsigned int timeout)
+{
+	struct atmel_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 atmel_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+	.firmware_version = 0,
+	.identity = "Atmel SAMA5D4 Watchdog",
+};
+
+static struct watchdog_ops atmel_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = atmel_wdt_start,
+	.stop = atmel_wdt_stop,
+	.ping = atmel_wdt_ping,
+	.set_timeout = atmel_wdt_set_timeout,
+};
+
+static irqreturn_t atmel_wdt_irq_handler(int irq, void *dev_id)
+{
+	struct atmel_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 ?????\n");
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int of_atmel_wdt_init(struct device_node *np, struct atmel_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 atmel_wdt_init(struct atmel_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 atmel_wdt_probe(struct platform_device *pdev)
+{
+	struct watchdog_device *wdd;
+	struct atmel_wdt *wdt;
+	struct resource *res;
+	void __iomem *regs;
+	int ret, irq = -1;
+
+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdd = &wdt->wdd;
+	wdd->timeout = wdt_timeout;
+	wdd->info = &atmel_wdt_info;
+	wdd->ops = &atmel_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_atmel_wdt_init(pdev->dev.of_node, wdt);
+		if (ret)
+			return ret;
+	}
+
+	if ((wdt->config & AT91_WDT_WDFIEN) && irq > 0) {
+		ret = devm_request_irq(&pdev->dev, irq, atmel_wdt_irq_handler,
+				       0, 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 = atmel_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 atmel_wdt_remove(struct platform_device *pdev)
+{
+	struct atmel_wdt *wdt = platform_get_drvdata(pdev);
+
+	atmel_wdt_stop(&wdt->wdd);
+
+	watchdog_unregister_device(&wdt->wdd);
+
+	return 0;
+}
+
+static const struct of_device_id atmel_wdt_of_match[] = {
+	{ .compatible = "atmel,sama5d4-wdt", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, atmel_wdt_of_match);
+
+static struct platform_driver atmel_wdt_driver = {
+	.probe		= atmel_wdt_probe,
+	.remove		= atmel_wdt_remove,
+	.driver		= {
+		.name	= "sama5d4 wdt",
+		.of_match_table = atmel_wdt_of_match,
+	},
+};
+module_platform_driver(atmel_wdt_driver);
+
+MODULE_AUTHOR("Atmel Corporation");
+MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
+MODULE_LICENSE("GPL v2");
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 */
 
-- 
1.7.9.5

[PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Lothar Waßmann]

Hi,

> 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>
> ---
>  drivers/watchdog/Kconfig            |    9 ++
>  drivers/watchdog/Makefile           |    1 +
>  drivers/watchdog/at91_sama5d4_wdt.c |  279 +++++++++++++++++++++++++++++++++++
>  drivers/watchdog/at91sam9_wdt.h     |    2 +
>  4 files changed, 291 insertions(+)
>  create mode 100644 drivers/watchdog/at91_sama5d4_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index e5e7c55..4ce8346 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -152,6 +152,15 @@ config ARM_SP805_WATCHDOG
>  	  ARM Primecell SP805 Watchdog timer. This will reboot your system when
>  	  the timeout is reached.
>  
> +config AT91_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 AT91RM9200_WATCHDOG
>  	tristate "AT91RM9200 watchdog"
>  	depends on SOC_AT91RM9200 && MFD_SYSCON
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 5c19294..c57569c 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_AT91_SAMA5D4_WATCHDOG) += at91_sama5d4_wdt.o
consistency? Other AT91 entries don't have an '_' between 'AT91' and
the remainder of the Kconfig name.

>  obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
>  obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
[...]
> +static irqreturn_t atmel_wdt_irq_handler(int irq, void *dev_id)
> +{
> +	struct atmel_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 ?????\n");
>
Reboot didn't what? 'succeed' perhaps?

> +static const struct of_device_id atmel_wdt_of_match[] = {
> +	{ .compatible = "atmel,sama5d4-wdt", },
> +	{ },
The empty initializer must always be the last element of the array, so
there is no point in having a trailing ',' (whose purpose is to
facilitate adding more entries after the last one).
Without the comma there will be a compile error if (e.g. due to a
badly resolved merge conflict) an additional entry would be added after
the stop marker. With the comma after the stop marker any trailing
entries would silently be ignored.


Lothar Wa?mann
-- 
___________________________________________________________

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___________________________________________________________

[PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Yang, Wenyou]

Hi Lothar,

Thank you for your review.

> -----Original Message-----
> From: Lothar Wa?mann [mailto:LW at KARO-electronics.de]
> Sent: 2015?8?5? 18:41
> To: Yang, Wenyou
> Cc: wim at iguana.be; robh+dt at kernel.org; pawel.moll at arm.com;
> mark.rutland at arm.com; ijc+devicetree at hellion.org.uk; galak at codeaurora.org;
> boris.brezillon at free-electrons.com; linux-watchdog at vger.kernel.org;
> devicetree at vger.kernel.org; sylvain.rochet at finsecur.com; Ferre, Nicolas; linux-
> kernel at vger.kernel.org; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4
> watchdog timer
> 
> Hi,
> 
> > 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>
> > ---
> >  drivers/watchdog/Kconfig            |    9 ++
> >  drivers/watchdog/Makefile           |    1 +
> >  drivers/watchdog/at91_sama5d4_wdt.c |  279
> +++++++++++++++++++++++++++++++++++
> >  drivers/watchdog/at91sam9_wdt.h     |    2 +
> >  4 files changed, 291 insertions(+)
> >  create mode 100644 drivers/watchdog/at91_sama5d4_wdt.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > e5e7c55..4ce8346 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -152,6 +152,15 @@ config ARM_SP805_WATCHDOG
> >  	  ARM Primecell SP805 Watchdog timer. This will reboot your system
> when
> >  	  the timeout is reached.
> >
> > +config AT91_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 AT91RM9200_WATCHDOG
> >  	tristate "AT91RM9200 watchdog"
> >  	depends on SOC_AT91RM9200 && MFD_SYSCON diff --git
> > a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index
> > 5c19294..c57569c 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_AT91_SAMA5D4_WATCHDOG) += at91_sama5d4_wdt.o
> consistency? Other AT91 entries don't have an '_' between 'AT91' and the
> remainder of the Kconfig name.
Accept, Remove the prefix AT91_ , use the chip name directly, SAMA5D4 in next verison.

> 
> >  obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.ovi 
> >  obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
> [...]
> > +static irqreturn_t atmel_wdt_irq_handler(int irq, void *dev_id) {
> > +	struct atmel_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 ?????\n");
> >
> Reboot didn't what? 'succeed' perhaps?
Replace it with 'succeed' in next version. 

> 
> > +static const struct of_device_id atmel_wdt_of_match[] = {
> > +	{ .compatible = "atmel,sama5d4-wdt", },
> > +	{ },
> The empty initializer must always be the last element of the array, so there is no
> point in having a trailing ',' (whose purpose is to facilitate adding more entries after
> the last one).
> Without the comma there will be a compile error if (e.g. due to a badly resolved
> merge conflict) an additional entry would be added after the stop marker. With the
> comma after the stop marker any trailing entries would silently be ignored.
Remove this comma in next version.

> 
> 
> Lothar Wa?mann
> --
> ___________________________________________________________
> 
> Ka-Ro electronics GmbH | Pascalstra?e 22 | D - 52076 Aachen
> Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
> Gesch?ftsf?hrer: Matthias Kaussen
> Handelsregistereintrag: Amtsgericht Aachen, HRB 4996
> 
> www.karo-electronics.de | info at karo-electronics.de
> ___________________________________________________________

Best Regards,
Wenyou 

[PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Guenter Roeck]

On 08/05/2015 01:57 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>
> ---
>   drivers/watchdog/Kconfig            |    9 ++
>   drivers/watchdog/Makefile           |    1 +
>   drivers/watchdog/at91_sama5d4_wdt.c |  279 +++++++++++++++++++++++++++++++++++
>   drivers/watchdog/at91sam9_wdt.h     |    2 +
>   4 files changed, 291 insertions(+)
>   create mode 100644 drivers/watchdog/at91_sama5d4_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index e5e7c55..4ce8346 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -152,6 +152,15 @@ config ARM_SP805_WATCHDOG
>   	  ARM Primecell SP805 Watchdog timer. This will reboot your system when
>   	  the timeout is reached.
>
> +config AT91_SAMA5D4_WATCHDOG

Looking into the chip ordering documentation. The chip goes by ATSAMA5D4,
while the other chips go by AT91SAM9xxx.

So I think ATSAMA5D4 would be better (same for the driver name).

Couple of additional nitpicks below.

Thanks,
Guenter

> +	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 AT91RM9200_WATCHDOG
>   	tristate "AT91RM9200 watchdog"
>   	depends on SOC_AT91RM9200 && MFD_SYSCON
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 5c19294..c57569c 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-$(CONFIG_AT91_SAMA5D4_WATCHDOG) += at91_sama5d4_wdt.o
>   obj-$(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/at91_sama5d4_wdt.c b/drivers/watchdog/at91_sama5d4_wdt.c
> new file mode 100644
> index 0000000..f2e1995
> --- /dev/null
> +++ b/drivers/watchdog/at91_sama5d4_wdt.c
> @@ -0,0 +1,279 @@
> +/*
> + * 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 atmel_wdt {

If you don't mind, please use "sama5d4" as prefix here and for function names.

> +	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 wdt_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 atmel_wdt_start(struct watchdog_device *wdd)
> +{
> +	struct atmel_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 atmel_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct atmel_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 atmel_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> +	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
> +
> +	return 0;
> +}
> +
> +static int atmel_wdt_set_timeout(struct watchdog_device *wdd,
> +				 unsigned int timeout)
> +{
> +	struct atmel_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 atmel_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> +	.firmware_version = 0,

Unnecessary initialization.

> +	.identity = "Atmel SAMA5D4 Watchdog",
> +};
> +
> +static struct watchdog_ops atmel_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = atmel_wdt_start,
> +	.stop = atmel_wdt_stop,
> +	.ping = atmel_wdt_ping,
> +	.set_timeout = atmel_wdt_set_timeout,
> +};
> +
> +static irqreturn_t atmel_wdt_irq_handler(int irq, void *dev_id)
> +{
> +	struct atmel_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 ?????\n");
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int of_atmel_wdt_init(struct device_node *np, struct atmel_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 atmel_wdt_init(struct atmel_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 atmel_wdt_probe(struct platform_device *pdev)
> +{
> +	struct watchdog_device *wdd;
> +	struct atmel_wdt *wdt;
> +	struct resource *res;
> +	void __iomem *regs;
> +	int ret, irq = -1;

Might as well use irq = 0 here for consistency.

> +
> +	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> +	if (!wdt)
> +		return -ENOMEM;
> +
> +	wdd = &wdt->wdd;
> +	wdd->timeout = wdt_timeout;
> +	wdd->info = &atmel_wdt_info;
> +	wdd->ops = &atmel_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_atmel_wdt_init(pdev->dev.of_node, wdt);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if ((wdt->config & AT91_WDT_WDFIEN) && irq > 0) {

... then you can check " ... && irq" here.

> +		ret = devm_request_irq(&pdev->dev, irq, atmel_wdt_irq_handler,
> +				       0, 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 = atmel_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 atmel_wdt_remove(struct platform_device *pdev)
> +{
> +	struct atmel_wdt *wdt = platform_get_drvdata(pdev);
> +
> +	atmel_wdt_stop(&wdt->wdd);
> +
> +	watchdog_unregister_device(&wdt->wdd);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id atmel_wdt_of_match[] = {
> +	{ .compatible = "atmel,sama5d4-wdt", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, atmel_wdt_of_match);
> +
> +static struct platform_driver atmel_wdt_driver = {
> +	.probe		= atmel_wdt_probe,
> +	.remove		= atmel_wdt_remove,
> +	.driver		= {
> +		.name	= "sama5d4 wdt",
> +		.of_match_table = atmel_wdt_of_match,
> +	},
> +};
> +module_platform_driver(atmel_wdt_driver);
> +
> +MODULE_AUTHOR("Atmel Corporation");
> +MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
> +MODULE_LICENSE("GPL v2");
> 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 */
>
>

[PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Yang, Wenyou]

Hi Guenter,

Thank you for your review.

> -----Original Message-----
> From: Guenter Roeck [mailto:linux at roeck-us.net]
> Sent: 2015?8?5? 23:05
> To: Yang, Wenyou; wim at iguana.be; robh+dt at kernel.org; pawel.moll at arm.com;
> mark.rutland at arm.com; ijc+devicetree at hellion.org.uk; galak at codeaurora.org
> Cc: sylvain.rochet at finsecur.com; Ferre, Nicolas; boris.brezillon at free-
> electrons.com; devicetree at vger.kernel.org; linux-kernel at vger.kernel.org; linux-
> watchdog at vger.kernel.org; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4
> watchdog timer
> 
> On 08/05/2015 01:57 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>
> > ---
> >   drivers/watchdog/Kconfig            |    9 ++
> >   drivers/watchdog/Makefile           |    1 +
> >   drivers/watchdog/at91_sama5d4_wdt.c |  279
> +++++++++++++++++++++++++++++++++++
> >   drivers/watchdog/at91sam9_wdt.h     |    2 +
> >   4 files changed, 291 insertions(+)
> >   create mode 100644 drivers/watchdog/at91_sama5d4_wdt.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > e5e7c55..4ce8346 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -152,6 +152,15 @@ config ARM_SP805_WATCHDOG
> >   	  ARM Primecell SP805 Watchdog timer. This will reboot your system
> when
> >   	  the timeout is reached.
> >
> > +config AT91_SAMA5D4_WATCHDOG
> 
> Looking into the chip ordering documentation. The chip goes by ATSAMA5D4,
> while the other chips go by AT91SAM9xxx.
> 
> So I think ATSAMA5D4 would be better (same for the driver name).
Use SAMA5D4 directly, the chip name.

> 
> Couple of additional nitpicks below.
I will change it in the next version, thanks.

> 
> Thanks,
> Guenter
> 
> > +	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 AT91RM9200_WATCHDOG
> >   	tristate "AT91RM9200 watchdog"
> >   	depends on SOC_AT91RM9200 && MFD_SYSCON diff --git
> > a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index
> > 5c19294..c57569c 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-$(CONFIG_AT91_SAMA5D4_WATCHDOG) += at91_sama5d4_wdt.o
> >   obj-$(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/at91_sama5d4_wdt.c
> > b/drivers/watchdog/at91_sama5d4_wdt.c
> > new file mode 100644
> > index 0000000..f2e1995
> > --- /dev/null
> > +++ b/drivers/watchdog/at91_sama5d4_wdt.c
> > @@ -0,0 +1,279 @@
> > +/*
> > + * 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 atmel_wdt {
> 
> If you don't mind, please use "sama5d4" as prefix here and for function names.
> 
> > +	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 wdt_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 atmel_wdt_start(struct watchdog_device *wdd) {
> > +	struct atmel_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 atmel_wdt_stop(struct watchdog_device *wdd) {
> > +	struct atmel_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 atmel_wdt_ping(struct watchdog_device *wdd) {
> > +	struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > +
> > +	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY |
> AT91_WDT_WDRSTT);
> > +
> > +	return 0;
> > +}
> > +
> > +static int atmel_wdt_set_timeout(struct watchdog_device *wdd,
> > +				 unsigned int timeout)
> > +{
> > +	struct atmel_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 atmel_wdt_info = {
> > +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
> WDIOF_KEEPALIVEPING,
> > +	.firmware_version = 0,
> 
> Unnecessary initialization.
> 
> > +	.identity = "Atmel SAMA5D4 Watchdog", };
> > +
> > +static struct watchdog_ops atmel_wdt_ops = {
> > +	.owner = THIS_MODULE,
> > +	.start = atmel_wdt_start,
> > +	.stop = atmel_wdt_stop,
> > +	.ping = atmel_wdt_ping,
> > +	.set_timeout = atmel_wdt_set_timeout, };
> > +
> > +static irqreturn_t atmel_wdt_irq_handler(int irq, void *dev_id) {
> > +	struct atmel_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 ?????\n");
> > +	}
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int of_atmel_wdt_init(struct device_node *np, struct atmel_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 atmel_wdt_init(struct atmel_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 atmel_wdt_probe(struct platform_device *pdev) {
> > +	struct watchdog_device *wdd;
> > +	struct atmel_wdt *wdt;
> > +	struct resource *res;
> > +	void __iomem *regs;
> > +	int ret, irq = -1;
> 
> Might as well use irq = 0 here for consistency.
> 
> > +
> > +	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> > +	if (!wdt)
> > +		return -ENOMEM;
> > +
> > +	wdd = &wdt->wdd;
> > +	wdd->timeout = wdt_timeout;
> > +	wdd->info = &atmel_wdt_info;
> > +	wdd->ops = &atmel_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_atmel_wdt_init(pdev->dev.of_node, wdt);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	if ((wdt->config & AT91_WDT_WDFIEN) && irq > 0) {
> 
> ... then you can check " ... && irq" here.
> 
> > +		ret = devm_request_irq(&pdev->dev, irq, atmel_wdt_irq_handler,
> > +				       0, 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 = atmel_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 atmel_wdt_remove(struct platform_device *pdev) {
> > +	struct atmel_wdt *wdt = platform_get_drvdata(pdev);
> > +
> > +	atmel_wdt_stop(&wdt->wdd);
> > +
> > +	watchdog_unregister_device(&wdt->wdd);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id atmel_wdt_of_match[] = {
> > +	{ .compatible = "atmel,sama5d4-wdt", },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, atmel_wdt_of_match);
> > +
> > +static struct platform_driver atmel_wdt_driver = {
> > +	.probe		= atmel_wdt_probe,
> > +	.remove		= atmel_wdt_remove,
> > +	.driver		= {
> > +		.name	= "sama5d4 wdt",
> > +		.of_match_table = atmel_wdt_of_match,
> > +	},
> > +};
> > +module_platform_driver(atmel_wdt_driver);
> > +
> > +MODULE_AUTHOR("Atmel Corporation");
> > +MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
> > +MODULE_LICENSE("GPL v2");
> > 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 */
> >
> >
Best Regards,
Wenyou Yang

[PATCH v3 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 at 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