[PATCH v2 0/4] ARM: meson: watchdog driver

[PATCH v2 0/4] ARM: meson: watchdog driver

[Carlo Caione]

This patchset adds support for the watchdog found on Amlogic MesonX SoCs. The
watchdog is used also to reboot the device.

DTSI and multi_v7_defconfig are updated and proper documentation is added.

No documentation is provided by Amlogic, the code is reverse-engineered by the
code available at http://openlinux.amlogic.com:8000/download/

This patchset depends on:
[1] [PATCH 0/6] ARM: meson: initial support for MesonX SoCs
[2] [PATCH 0/2] ARM: meson: add clocksource support

Changes since v1:
* added restart handler support

[1] http://www.spinics.net/lists/arm-kernel/msg362521.html
[2] http://www.spinics.net/lists/arm-kernel/msg362483.html

Carlo Caione (4):
  ARM: docs: add documentation binding for meson watchdog
  ARM: meson: add watchdog driver
  ARM: DTS: meson: update DTSI to add watchdog node
  ARM: defconfig: update multi_v7_defconfig

 .../devicetree/bindings/watchdog/meson-wdt.txt     |  13 ++
 arch/arm/boot/dts/meson.dtsi                       |   5 +
 arch/arm/configs/multi_v7_defconfig                |   1 +
 drivers/watchdog/Kconfig                           |  10 +
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/meson_wdt.c                       | 237 +++++++++++++++++++++
 6 files changed, 267 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/meson-wdt.txt
 create mode 100644 drivers/watchdog/meson_wdt.c

-- 
1.9.1

[PATCH v2 1/4] ARM: docs: add documentation binding for meson watchdog

[Carlo Caione]

Signed-off-by: Carlo Caione <carlo@caione.org>
---
 Documentation/devicetree/bindings/watchdog/meson-wdt.txt | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/meson-wdt.txt

diff --git a/Documentation/devicetree/bindings/watchdog/meson-wdt.txt b/Documentation/devicetree/bindings/watchdog/meson-wdt.txt
new file mode 100644
index 0000000..e66c0c3
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/meson-wdt.txt
@@ -0,0 +1,13 @@
+Meson SoCs Watchdog timer
+
+Required properties:
+
+- compatible : should be "amlogic,meson-wdt"
+- reg : Specifies base physical address and size of the registers.
+
+Example:
+
+wdt: watchdog at c1109900 {
+	compatible = "amlogic,meson-wdt";
+	reg = <0xc1109900 0x8>;
+};
-- 
1.9.1

[PATCH v2 2/4] ARM: meson: add watchdog driver

[Carlo Caione]

This patch adds the watchdog driver for the Amlogic Meson SoCs used also
to reboot the device.

Signed-off-by: Carlo Caione <carlo@caione.org>
---
 drivers/watchdog/Kconfig     |  10 ++
 drivers/watchdog/Makefile    |   1 +
 drivers/watchdog/meson_wdt.c | 237 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 248 insertions(+)
 create mode 100644 drivers/watchdog/meson_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index f57312f..836cb00 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -443,6 +443,16 @@ config TEGRA_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called tegra_wdt.
 
+config MESON_WATCHDOG
+	tristate "Amlogic Meson SoCs watchdog support"
+	depends on ARCH_MESON
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support for the watchdog timer
+	  in Amlogic Meson SoCs.
+	  To compile this driver as a module, choose M here: the
+	  module will be called meson_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 468c320..e7a9259 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_MOXART_WDT) += moxart_wdt.o
 obj-$(CONFIG_SIRFSOC_WATCHDOG) += sirfsoc_wdt.o
 obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
 obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
+obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/meson_wdt.c b/drivers/watchdog/meson_wdt.c
new file mode 100644
index 0000000..3fbe147
--- /dev/null
+++ b/drivers/watchdog/meson_wdt.c
@@ -0,0 +1,237 @@
+/*
+ *      Meson Watchdog Driver
+ *
+ *      Copyright (c) 2014 Carlo Caione
+ *
+ *      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.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define DRV_NAME		"meson_wdt"
+
+#define MESON_WDT_TC		0x00
+#define MESON_WDT_TC_EN		BIT(22)
+#define MESON_WDT_TC_TM_MASK	0x3fffff
+#define MESON_WDT_DC_RESET	(3 << 24)
+
+#define MESON_WDT_RESET		0x04
+
+#define MESON_WDT_TIMEOUT	40
+#define MESON_WDT_MIN_TIMEOUT	1
+#define MESON_WDT_MAX_TIMEOUT	30
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+static unsigned int timeout = MESON_WDT_TIMEOUT;
+
+struct meson_wdt_dev {
+	struct watchdog_device wdt_dev;
+	void __iomem *wdt_base;
+	struct notifier_block restart_handler;
+};
+
+static int meson_restart_handle(struct notifier_block *this, unsigned long mode,
+				void *cmd)
+{
+	u32 tc_reboot = MESON_WDT_DC_RESET | MESON_WDT_TC_EN | 100;
+	struct meson_wdt_dev *meson_wdt = container_of(this,
+						       struct meson_wdt_dev,
+						       restart_handler);
+
+	writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
+	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
+
+	while (1) {
+		mdelay(5);
+		writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int meson_wdt_ping(struct watchdog_device *wdt_dev)
+{
+	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
+
+	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
+
+	return 0;
+}
+
+static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
+				 unsigned int timeout)
+{
+	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
+	u32 reg;
+
+	meson_wdt->wdt_dev.timeout = timeout;
+
+	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
+	reg &= ~MESON_WDT_TC_TM_MASK;
+	reg |= (timeout * 100 * 1000);
+	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
+
+	meson_wdt_ping(wdt_dev);
+
+	return 0;
+}
+
+static int meson_wdt_stop(struct watchdog_device *wdt_dev)
+{
+	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
+	u32 reg;
+
+	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
+	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
+	reg &= ~MESON_WDT_TC_EN;
+	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
+
+	return 0;
+}
+
+static int meson_wdt_start(struct watchdog_device *wdt_dev)
+{
+	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
+	u32 reg;
+	int ret;
+
+	ret = meson_wdt_set_timeout(&meson_wdt->wdt_dev,
+				    meson_wdt->wdt_dev.timeout);
+	if (ret < 0)
+		return ret;
+
+	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
+	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
+	reg |= MESON_WDT_TC_EN;
+	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
+
+	return 0;
+}
+
+static const struct watchdog_info meson_wdt_info = {
+	.identity	= DRV_NAME,
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE,
+};
+
+static const struct watchdog_ops meson_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= meson_wdt_start,
+	.stop		= meson_wdt_stop,
+	.ping		= meson_wdt_ping,
+	.set_timeout	= meson_wdt_set_timeout,
+};
+
+static int meson_wdt_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct meson_wdt_dev *meson_wdt;
+	int err;
+
+	meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
+	if (!meson_wdt)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(meson_wdt->wdt_base))
+		return PTR_ERR(meson_wdt->wdt_base);
+
+	meson_wdt->wdt_dev.parent = &pdev->dev;
+	meson_wdt->wdt_dev.info = &meson_wdt_info;
+	meson_wdt->wdt_dev.ops = &meson_wdt_ops;
+	meson_wdt->wdt_dev.timeout = MESON_WDT_TIMEOUT;
+	meson_wdt->wdt_dev.max_timeout = MESON_WDT_MAX_TIMEOUT;
+	meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
+
+	watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
+
+	watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
+	watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
+
+	meson_wdt_stop(&meson_wdt->wdt_dev);
+
+	err = watchdog_register_device(&meson_wdt->wdt_dev);
+	if (unlikely(err))
+		return err;
+
+	platform_set_drvdata(pdev, meson_wdt);
+
+	meson_wdt->restart_handler.notifier_call = meson_restart_handle;
+	meson_wdt->restart_handler.priority = 128;
+	err = register_restart_handler(&meson_wdt->restart_handler);
+	if (err)
+		dev_err(&pdev->dev,
+			"cannot register restart handler (err=%d)\n", err);
+
+	dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
+		 meson_wdt->wdt_dev.timeout, nowayout);
+
+	return 0;
+}
+
+static int meson_wdt_remove(struct platform_device *pdev)
+{
+	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
+
+	unregister_restart_handler(&meson_wdt->restart_handler);
+
+	watchdog_unregister_device(&meson_wdt->wdt_dev);
+	watchdog_set_drvdata(&meson_wdt->wdt_dev, NULL);
+
+	return 0;
+}
+
+static void meson_wdt_shutdown(struct platform_device *pdev)
+{
+	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
+
+	meson_wdt_stop(&meson_wdt->wdt_dev);
+}
+
+static const struct of_device_id meson_wdt_dt_ids[] = {
+	{ .compatible = "amlogic,meson-wdt" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
+
+static struct platform_driver meson_wdt_driver = {
+	.probe		= meson_wdt_probe,
+	.remove		= meson_wdt_remove,
+	.shutdown	= meson_wdt_shutdown,
+	.driver		= {
+		.owner		= THIS_MODULE,
+		.name		= DRV_NAME,
+		.of_match_table	= meson_wdt_dt_ids,
+	},
+};
+
+module_platform_driver(meson_wdt_driver);
+
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
+
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+		"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
+MODULE_DESCRIPTION("Meson Watchdog Timer Driver");
-- 
1.9.1

[PATCH v2 3/4] ARM: DTS: meson: update DTSI to add watchdog node

[Carlo Caione]

Signed-off-by: Carlo Caione <carlo@caione.org>
---
 arch/arm/boot/dts/meson.dtsi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/boot/dts/meson.dtsi b/arch/arm/boot/dts/meson.dtsi
index 55feb14..ebe7742 100644
--- a/arch/arm/boot/dts/meson.dtsi
+++ b/arch/arm/boot/dts/meson.dtsi
@@ -70,6 +70,11 @@
 		#size-cells = <1>;
 		ranges;
 
+		wdt: watchdog at c1109900 {
+			compatible = "amlogic,meson-wdt";
+			reg = <0xc1109900 0x8>;
+		};
+
 		uart_AO: serial at c81004c0 {
 			compatible = "amlogic,meson-uart";
 			reg = <0xc81004c0 0x14>;
-- 
1.9.1

[PATCH v2 4/4] ARM: defconfig: update multi_v7_defconfig

[Carlo Caione]

Update the multi_v7_defconfig enabling the watchdog driver for Meson
SoCs.

Signed-off-by: Carlo Caione <carlo@caione.org>
---
 arch/arm/configs/multi_v7_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig
index 5b44796..560e6a9 100644
--- a/arch/arm/configs/multi_v7_defconfig
+++ b/arch/arm/configs/multi_v7_defconfig
@@ -242,6 +242,7 @@ CONFIG_ST_THERMAL_MEMMAP=y
 CONFIG_WATCHDOG=y
 CONFIG_ORION_WATCHDOG=y
 CONFIG_SUNXI_WATCHDOG=y
+CONFIG_MESON_WATCHDOG=y
 CONFIG_MFD_AS3722=y
 CONFIG_MFD_BCM590XX=y
 CONFIG_MFD_CROS_EC=y
-- 
1.9.1

[PATCH v2 1/4] ARM: docs: add documentation binding for meson watchdog

[Beniamino Galvani]

On Wed, Sep 17, 2014 at 10:12:03PM +0200, Carlo Caione wrote:
> Signed-off-by: Carlo Caione <carlo@caione.org>
> ---
>  Documentation/devicetree/bindings/watchdog/meson-wdt.txt | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/watchdog/meson-wdt.txt
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/meson-wdt.txt b/Documentation/devicetree/bindings/watchdog/meson-wdt.txt
> new file mode 100644
> index 0000000..e66c0c3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/meson-wdt.txt
> @@ -0,0 +1,13 @@
> +Meson SoCs Watchdog timer
> +
> +Required properties:
> +
> +- compatible : should be "amlogic,meson-wdt"

Hi Carlo,

the compatible property should describe a specific version of the
device, so maybe "amlogic,meson6-wdt" would be more appropriate.

Beniamino

> +- reg : Specifies base physical address and size of the registers.
> +
> +Example:
> +
> +wdt: watchdog at c1109900 {
> +	compatible = "amlogic,meson-wdt";
> +	reg = <0xc1109900 0x8>;
> +};
> -- 
> 1.9.1
> 

[PATCH v2 2/4] ARM: meson: add watchdog driver

[Guenter Roeck]

On 09/17/2014 01:12 PM, Carlo Caione wrote:
> This patch adds the watchdog driver for the Amlogic Meson SoCs used also
> to reboot the device.
>
> Signed-off-by: Carlo Caione <carlo@caione.org>
> ---
>   drivers/watchdog/Kconfig     |  10 ++
>   drivers/watchdog/Makefile    |   1 +
>   drivers/watchdog/meson_wdt.c | 237 +++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 248 insertions(+)
>   create mode 100644 drivers/watchdog/meson_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index f57312f..836cb00 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -443,6 +443,16 @@ config TEGRA_WATCHDOG
>   	  To compile this driver as a module, choose M here: the
>   	  module will be called tegra_wdt.
>
> +config MESON_WATCHDOG
> +	tristate "Amlogic Meson SoCs watchdog support"
> +	depends on ARCH_MESON
> +	select WATCHDOG_CORE
> +	help
> +	  Say Y here to include support for the watchdog timer
> +	  in Amlogic Meson SoCs.
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called meson_wdt.
> +
>   # AVR32 Architecture
>
>   config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 468c320..e7a9259 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -59,6 +59,7 @@ obj-$(CONFIG_MOXART_WDT) += moxart_wdt.o
>   obj-$(CONFIG_SIRFSOC_WATCHDOG) += sirfsoc_wdt.o
>   obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
>   obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
> +obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
>
>   # AVR32 Architecture
>   obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/meson_wdt.c b/drivers/watchdog/meson_wdt.c
> new file mode 100644
> index 0000000..3fbe147
> --- /dev/null
> +++ b/drivers/watchdog/meson_wdt.c
> @@ -0,0 +1,237 @@
> +/*
> + *      Meson Watchdog Driver
> + *
> + *      Copyright (c) 2014 Carlo Caione
> + *
> + *      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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/notifier.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/types.h>
> +#include <linux/watchdog.h>
> +
> +#define DRV_NAME		"meson_wdt"
> +
> +#define MESON_WDT_TC		0x00
> +#define MESON_WDT_TC_EN		BIT(22)
> +#define MESON_WDT_TC_TM_MASK	0x3fffff
> +#define MESON_WDT_DC_RESET	(3 << 24)
> +
> +#define MESON_WDT_RESET		0x04
> +
Does this all use the same indentation ? Looks a bit odd.

> +#define MESON_WDT_TIMEOUT	40
> +#define MESON_WDT_MIN_TIMEOUT	1
> +#define MESON_WDT_MAX_TIMEOUT	30
> +

Default timeout is 40 seconds, maximum timeout is 30 seconds ?
That doesn't really make much sense. What is the real maximum timeout ?
If it is 0x3fffff / 100000, as the code suggests, you should set
MAX_TIMEOUT to 41 or possibly (0x3fffff / 100000) so people understand
what is going on.

> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +static unsigned int timeout = MESON_WDT_TIMEOUT;
> +
> +struct meson_wdt_dev {
> +	struct watchdog_device wdt_dev;
> +	void __iomem *wdt_base;
> +	struct notifier_block restart_handler;
> +};
> +
> +static int meson_restart_handle(struct notifier_block *this, unsigned long mode,
> +				void *cmd)
> +{
> +	u32 tc_reboot = MESON_WDT_DC_RESET | MESON_WDT_TC_EN | 100;

What does the magic 100 do ?

> +	struct meson_wdt_dev *meson_wdt = container_of(this,
> +						       struct meson_wdt_dev,
> +						       restart_handler);
> +
> +	writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
> +	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
> +
Is this sequence necessary ? Just asking, looks a bit odd.

> +	while (1) {
> +		mdelay(5);
> +		writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int meson_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> +
> +	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
> +
> +	return 0;
> +}
> +
> +static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
> +				 unsigned int timeout)
> +{
> +	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> +	u32 reg;
> +
> +	meson_wdt->wdt_dev.timeout = timeout;
> +
> +	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
> +	reg &= ~MESON_WDT_TC_TM_MASK;
> +	reg |= (timeout * 100 * 1000);

A define for the clock rate might be helpful.

> +	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
> +
> +	meson_wdt_ping(wdt_dev);
> +
> +	return 0;
> +}
> +
> +static int meson_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> +	u32 reg;
> +
> +	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);

Is this final ping really needed here ?

> +	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
> +	reg &= ~MESON_WDT_TC_EN;
> +	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
> +
> +	return 0;
> +}
> +
> +static int meson_wdt_start(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> +	u32 reg;
> +	int ret;
> +
> +	ret = meson_wdt_set_timeout(&meson_wdt->wdt_dev,
> +				    meson_wdt->wdt_dev.timeout);

Not really sure if that is such a good idea here, as the set_timeout
function does a bit more than just writing the timeout into the register.
If you don't want to hard-code it here, I would suggest to write a
little helper function which only writes it into the register
(which would be called from both here and from meson_wdt_set_timeout).

> +	if (ret < 0)
> +		return ret;
> +
> +	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
> +	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
> +	reg |= MESON_WDT_TC_EN;
> +	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info meson_wdt_info = {
> +	.identity	= DRV_NAME,
> +	.options	= WDIOF_SETTIMEOUT |
> +			  WDIOF_KEEPALIVEPING |
> +			  WDIOF_MAGICCLOSE,
> +};
> +
> +static const struct watchdog_ops meson_wdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= meson_wdt_start,
> +	.stop		= meson_wdt_stop,
> +	.ping		= meson_wdt_ping,
> +	.set_timeout	= meson_wdt_set_timeout,
> +};
> +
> +static int meson_wdt_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	struct meson_wdt_dev *meson_wdt;
> +	int err;
> +
> +	meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
> +	if (!meson_wdt)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(meson_wdt->wdt_base))
> +		return PTR_ERR(meson_wdt->wdt_base);
> +
> +	meson_wdt->wdt_dev.parent = &pdev->dev;
> +	meson_wdt->wdt_dev.info = &meson_wdt_info;
> +	meson_wdt->wdt_dev.ops = &meson_wdt_ops;
> +	meson_wdt->wdt_dev.timeout = MESON_WDT_TIMEOUT;
> +	meson_wdt->wdt_dev.max_timeout = MESON_WDT_MAX_TIMEOUT;
> +	meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
> +
> +	watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
> +
> +	watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
> +	watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
> +
> +	meson_wdt_stop(&meson_wdt->wdt_dev);
> +
> +	err = watchdog_register_device(&meson_wdt->wdt_dev);
> +	if (unlikely(err))
> +		return err;

Please drop the unlikely.

> +
> +	platform_set_drvdata(pdev, meson_wdt);
> +
> +	meson_wdt->restart_handler.notifier_call = meson_restart_handle;
> +	meson_wdt->restart_handler.priority = 128;
> +	err = register_restart_handler(&meson_wdt->restart_handler);
> +	if (err)
> +		dev_err(&pdev->dev,
> +			"cannot register restart handler (err=%d)\n", err);
> +
> +	dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
> +		 meson_wdt->wdt_dev.timeout, nowayout);
> +
> +	return 0;
> +}
> +
> +static int meson_wdt_remove(struct platform_device *pdev)
> +{
> +	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
> +
> +	unregister_restart_handler(&meson_wdt->restart_handler);
> +
> +	watchdog_unregister_device(&meson_wdt->wdt_dev);
> +	watchdog_set_drvdata(&meson_wdt->wdt_dev, NULL);

Unnecessary.

> +
> +	return 0;
> +}
> +
> +static void meson_wdt_shutdown(struct platform_device *pdev)
> +{
> +	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
> +
> +	meson_wdt_stop(&meson_wdt->wdt_dev);
> +}
> +
> +static const struct of_device_id meson_wdt_dt_ids[] = {
> +	{ .compatible = "amlogic,meson-wdt" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
> +
> +static struct platform_driver meson_wdt_driver = {
> +	.probe		= meson_wdt_probe,
> +	.remove		= meson_wdt_remove,
> +	.shutdown	= meson_wdt_shutdown,
> +	.driver		= {
> +		.owner		= THIS_MODULE,
> +		.name		= DRV_NAME,
> +		.of_match_table	= meson_wdt_dt_ids,
> +	},
> +};
> +
> +module_platform_driver(meson_wdt_driver);
> +
> +module_param(timeout, uint, 0);
> +MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
> +
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
> +		"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
> +MODULE_DESCRIPTION("Meson Watchdog Timer Driver");
>

[PATCH v2 2/4] ARM: meson: add watchdog driver

[Carlo Caione]

On Fri, Sep 19, 2014 at 5:31 AM, Guenter Roeck <linux@roeck-us.net> wrote:
> On 09/17/2014 01:12 PM, Carlo Caione wrote:
>>
>> This patch adds the watchdog driver for the Amlogic Meson SoCs used also
>> to reboot the device.
>>
>> Signed-off-by: Carlo Caione <carlo@caione.org>
>> ---
>>   drivers/watchdog/Kconfig     |  10 ++
>>   drivers/watchdog/Makefile    |   1 +
>>   drivers/watchdog/meson_wdt.c | 237
>> +++++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 248 insertions(+)
>>   create mode 100644 drivers/watchdog/meson_wdt.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index f57312f..836cb00 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -443,6 +443,16 @@ config TEGRA_WATCHDOG
>>           To compile this driver as a module, choose M here: the
>>           module will be called tegra_wdt.
>>
>> +config MESON_WATCHDOG
>> +       tristate "Amlogic Meson SoCs watchdog support"
>> +       depends on ARCH_MESON
>> +       select WATCHDOG_CORE
>> +       help
>> +         Say Y here to include support for the watchdog timer
>> +         in Amlogic Meson SoCs.
>> +         To compile this driver as a module, choose M here: the
>> +         module will be called meson_wdt.
>> +
>>   # AVR32 Architecture
>>
>>   config AT32AP700X_WDT
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index 468c320..e7a9259 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -59,6 +59,7 @@ obj-$(CONFIG_MOXART_WDT) += moxart_wdt.o
>>   obj-$(CONFIG_SIRFSOC_WATCHDOG) += sirfsoc_wdt.o
>>   obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
>>   obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
>> +obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
>>
>>   # AVR32 Architecture
>>   obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
>> diff --git a/drivers/watchdog/meson_wdt.c b/drivers/watchdog/meson_wdt.c
>> new file mode 100644
>> index 0000000..3fbe147
>> --- /dev/null
>> +++ b/drivers/watchdog/meson_wdt.c
>> @@ -0,0 +1,237 @@
>> +/*
>> + *      Meson Watchdog Driver
>> + *
>> + *      Copyright (c) 2014 Carlo Caione
>> + *
>> + *      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.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/init.h>
>> +#include <linux/io.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/moduleparam.h>
>> +#include <linux/notifier.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reboot.h>
>> +#include <linux/types.h>
>> +#include <linux/watchdog.h>
>> +
>> +#define DRV_NAME               "meson_wdt"
>> +
>> +#define MESON_WDT_TC           0x00
>> +#define MESON_WDT_TC_EN                BIT(22)
>> +#define MESON_WDT_TC_TM_MASK   0x3fffff
>> +#define MESON_WDT_DC_RESET     (3 << 24)
>> +
>> +#define MESON_WDT_RESET                0x04
>> +
>
> Does this all use the same indentation ? Looks a bit odd.

It does actually.

>> +#define MESON_WDT_TIMEOUT      40
>> +#define MESON_WDT_MIN_TIMEOUT  1
>> +#define MESON_WDT_MAX_TIMEOUT  30
>> +
>
>
> Default timeout is 40 seconds, maximum timeout is 30 seconds ?
> That doesn't really make much sense. What is the real maximum timeout ?
> If it is 0x3fffff / 100000, as the code suggests, you should set
> MAX_TIMEOUT to 41 or possibly (0x3fffff / 100000) so people understand
> what is going on.

I swapped the values, you are right. About the maximum values I wish I
had proper documentation to answer your question.
Anyway your guessing is probably right so I'll change it.

>> +static bool nowayout = WATCHDOG_NOWAYOUT;
>> +static unsigned int timeout = MESON_WDT_TIMEOUT;
>> +
>> +struct meson_wdt_dev {
>> +       struct watchdog_device wdt_dev;
>> +       void __iomem *wdt_base;
>> +       struct notifier_block restart_handler;
>> +};
>> +
>> +static int meson_restart_handle(struct notifier_block *this, unsigned
>> long mode,
>> +                               void *cmd)
>> +{
>> +       u32 tc_reboot = MESON_WDT_DC_RESET | MESON_WDT_TC_EN | 100;
>
>
> What does the magic 100 do ?

Just setting a really small timeout (I'm still not sure if 100 means
actually 1ms timeout or just "the minimum timeout")

>> +       struct meson_wdt_dev *meson_wdt = container_of(this,
>> +                                                      struct
>> meson_wdt_dev,
>> +                                                      restart_handler);
>> +
>> +       writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
>> +       writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
>> +
>
> Is this sequence necessary ? Just asking, looks a bit odd.

It was like that in the original code. I'll check if it is necessary.

>
>> +       while (1) {
>> +               mdelay(5);
>> +               writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
>> +       }
>> +
>> +       return NOTIFY_DONE;
>> +}
>> +
>> +static int meson_wdt_ping(struct watchdog_device *wdt_dev)
>> +{
>> +       struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
>> +
>> +       writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
>> +
>> +       return 0;
>> +}
>> +
>> +static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
>> +                                unsigned int timeout)
>> +{
>> +       struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
>> +       u32 reg;
>> +
>> +       meson_wdt->wdt_dev.timeout = timeout;
>> +
>> +       reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
>> +       reg &= ~MESON_WDT_TC_TM_MASK;
>> +       reg |= (timeout * 100 * 1000);
>
>
> A define for the clock rate might be helpful.

Agree

>> +       writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
>> +
>> +       meson_wdt_ping(wdt_dev);
>> +
>> +       return 0;
>> +}
>> +
>> +static int meson_wdt_stop(struct watchdog_device *wdt_dev)
>> +{
>> +       struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
>> +       u32 reg;
>> +
>> +       writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
>
>
> Is this final ping really needed here ?

I'll check it.

>> +       reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
>> +       reg &= ~MESON_WDT_TC_EN;
>> +       writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
>> +
>> +       return 0;
>> +}
>> +
>> +static int meson_wdt_start(struct watchdog_device *wdt_dev)
>> +{
>> +       struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
>> +       u32 reg;
>> +       int ret;
>> +
>> +       ret = meson_wdt_set_timeout(&meson_wdt->wdt_dev,
>> +                                   meson_wdt->wdt_dev.timeout);
>
>
> Not really sure if that is such a good idea here, as the set_timeout
> function does a bit more than just writing the timeout into the register.
> If you don't want to hard-code it here, I would suggest to write a
> little helper function which only writes it into the register
> (which would be called from both here and from meson_wdt_set_timeout).

Ok. I'll fix it in v3.

>
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
>> +       reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
>> +       reg |= MESON_WDT_TC_EN;
>> +       writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct watchdog_info meson_wdt_info = {
>> +       .identity       = DRV_NAME,
>> +       .options        = WDIOF_SETTIMEOUT |
>> +                         WDIOF_KEEPALIVEPING |
>> +                         WDIOF_MAGICCLOSE,
>> +};
>> +
>> +static const struct watchdog_ops meson_wdt_ops = {
>> +       .owner          = THIS_MODULE,
>> +       .start          = meson_wdt_start,
>> +       .stop           = meson_wdt_stop,
>> +       .ping           = meson_wdt_ping,
>> +       .set_timeout    = meson_wdt_set_timeout,
>> +};
>> +
>> +static int meson_wdt_probe(struct platform_device *pdev)
>> +{
>> +       struct resource *res;
>> +       struct meson_wdt_dev *meson_wdt;
>> +       int err;
>> +
>> +       meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt),
>> GFP_KERNEL);
>> +       if (!meson_wdt)
>> +               return -ENOMEM;
>> +
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
>> +       if (IS_ERR(meson_wdt->wdt_base))
>> +               return PTR_ERR(meson_wdt->wdt_base);
>> +
>> +       meson_wdt->wdt_dev.parent = &pdev->dev;
>> +       meson_wdt->wdt_dev.info = &meson_wdt_info;
>> +       meson_wdt->wdt_dev.ops = &meson_wdt_ops;
>> +       meson_wdt->wdt_dev.timeout = MESON_WDT_TIMEOUT;
>> +       meson_wdt->wdt_dev.max_timeout = MESON_WDT_MAX_TIMEOUT;
>> +       meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
>> +
>> +       watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
>> +
>> +       watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
>> +       watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
>> +
>> +       meson_wdt_stop(&meson_wdt->wdt_dev);
>> +
>> +       err = watchdog_register_device(&meson_wdt->wdt_dev);
>> +       if (unlikely(err))
>> +               return err;
>
>
> Please drop the unlikely.

Ok

>> +
>> +       platform_set_drvdata(pdev, meson_wdt);
>> +
>> +       meson_wdt->restart_handler.notifier_call = meson_restart_handle;
>> +       meson_wdt->restart_handler.priority = 128;
>> +       err = register_restart_handler(&meson_wdt->restart_handler);
>> +       if (err)
>> +               dev_err(&pdev->dev,
>> +                       "cannot register restart handler (err=%d)\n",
>> err);
>> +
>> +       dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec,
>> nowayout=%d)",
>> +                meson_wdt->wdt_dev.timeout, nowayout);
>> +
>> +       return 0;
>> +}
>> +
>> +static int meson_wdt_remove(struct platform_device *pdev)
>> +{
>> +       struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
>> +
>> +       unregister_restart_handler(&meson_wdt->restart_handler);
>> +
>> +       watchdog_unregister_device(&meson_wdt->wdt_dev);
>> +       watchdog_set_drvdata(&meson_wdt->wdt_dev, NULL);
>
>
> Unnecessary.

Ok

>
>> +
>> +       return 0;
>> +}
>> +
>> +static void meson_wdt_shutdown(struct platform_device *pdev)
>> +{
>> +       struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
>> +
>> +       meson_wdt_stop(&meson_wdt->wdt_dev);
>> +}
>> +
>> +static const struct of_device_id meson_wdt_dt_ids[] = {
>> +       { .compatible = "amlogic,meson-wdt" },
>> +       { /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
>> +
>> +static struct platform_driver meson_wdt_driver = {
>> +       .probe          = meson_wdt_probe,
>> +       .remove         = meson_wdt_remove,
>> +       .shutdown       = meson_wdt_shutdown,
>> +       .driver         = {
>> +               .owner          = THIS_MODULE,
>> +               .name           = DRV_NAME,
>> +               .of_match_table = meson_wdt_dt_ids,
>> +       },
>> +};
>> +
>> +module_platform_driver(meson_wdt_driver);
>> +
>> +module_param(timeout, uint, 0);
>> +MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
>> +
>> +module_param(nowayout, bool, 0);
>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
>> +               "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
>> +MODULE_DESCRIPTION("Meson Watchdog Timer Driver");

Thank you for the review.


-- 
Carlo Caione

[PATCH v2 1/4] ARM: docs: add documentation binding for meson watchdog

[Carlo Caione]

On Wed, Sep 17, 2014 at 10:58 PM, Beniamino Galvani <b.galvani@gmail.com> wrote:
> On Wed, Sep 17, 2014 at 10:12:03PM +0200, Carlo Caione wrote:
>> Signed-off-by: Carlo Caione <carlo@caione.org>
>> ---
>>  Documentation/devicetree/bindings/watchdog/meson-wdt.txt | 13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/watchdog/meson-wdt.txt
>>
>> diff --git a/Documentation/devicetree/bindings/watchdog/meson-wdt.txt b/Documentation/devicetree/bindings/watchdog/meson-wdt.txt
>> new file mode 100644
>> index 0000000..e66c0c3
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/watchdog/meson-wdt.txt
>> @@ -0,0 +1,13 @@
>> +Meson SoCs Watchdog timer
>> +
>> +Required properties:
>> +
>> +- compatible : should be "amlogic,meson-wdt"
>
> Hi Carlo,
>
> the compatible property should describe a specific version of the
> device, so maybe "amlogic,meson6-wdt" would be more appropriate.

Agree. Fix in v3.

Thanks,

-- 
Carlo Caione