[PATCH v3 0/5] STM32 Independant watchdog

[PATCH v3 0/5] STM32 Independant watchdog

[Yannick Fertre]

Version 3:
- Update typo into  bindings file
- Reorder node in devicetree (ordering by address)
- Remove unecessary lines in commits

Version 2:
- Add commit messages

Version 1:
- Initial commit

The purpose of this set of patches is to add a new watchdog driver for
stm32f429.
This driver was developed and tested on evaluation board stm32429i.

Yannick Fertre (5):
  dt-bindings: Document STM32 IWDG bindings
  drivers: watchdog: Add STM32 IWDG driver
  ARM: dts: stm32: Add watchdog support for STM32F429 SoC
  ARM: dts: stm32: Add watchdog support for STM32F429 eval board
  ARM: configs: Add watchdog support in STM32 defconfig

 .../devicetree/bindings/watchdog/st,stm32-iwdg.txt |  15 ++
 arch/arm/boot/dts/stm32429i-eval.dts               |   4 +
 arch/arm/boot/dts/stm32f429.dtsi                   |   9 +-
 arch/arm/configs/stm32_defconfig                   |   1 +
 drivers/watchdog/Kconfig                           |  11 +
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/stm32_iwdg.c                      | 289 +++++++++++++++++++++
 7 files changed, 329 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
 create mode 100644 drivers/watchdog/stm32_iwdg.c

-- 
1.9.1

[PATCH v3 1/5] dt-bindings: Document STM32 IWDG bindings

[Yannick Fertre]

From: Yannick Fertre <yfertre.stm32@gmail.com>

This adds documentation of device tree bindings for the STM32 IWDG
(Independent WatchDoG).

Change-Id: Idadacc806d00205fe9af2e8606af229b4b760558
Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
---
 .../devicetree/bindings/watchdog/st,stm32-iwdg.txt        | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt

diff --git a/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt b/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
new file mode 100644
index 0000000..036b040
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
@@ -0,0 +1,15 @@
+STM32 Independent WatchDoG (IWDG)
+---------------------------------
+
+Required properties:
+- compatible: "st,stm32-iwdg"
+- reg: physical base address and length of the registers set for the device
+- clocks: must contain a single entry describing the clock input
+
+Example:
+
+iwdg@40003000 {
+	compatible = "st,stm32-iwdg";
+	reg = <0x40003000 0x400>;
+	clocks = <&clk_lsi>;
+};
-- 
1.9.1

[PATCH v3 2/5] drivers: watchdog: Add STM32 IWDG driver

[Yannick Fertre]

This patch adds IWDG (Independent WatchDoG) support for STM32 platform.

Change-Id: Iab218745fc25566f12558fae7f52e2f8c21db74e
Signed-off-by: Yannick FERTRE <yannick.fertre@st.com>
---
 drivers/watchdog/Kconfig      |  11 ++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/stm32_iwdg.c | 289 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 301 insertions(+)
 create mode 100644 drivers/watchdog/stm32_iwdg.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 52a70ee..d9745a5 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -744,6 +744,17 @@ config ZX2967_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called zx2967_wdt.
 
+config STM32_WATCHDOG
+	tristate "STM32 Independent WatchDoG (IWDG) support"
+	depends on ARCH_STM32
+	select WATCHDOG_CORE
+	default y
+	help
+	  Say Y here to include Watchdog timer support.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called stm32_iwdg.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a2126e2..a35e423 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
 obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
 obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
 obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
+obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c
new file mode 100644
index 0000000..507dfc4
--- /dev/null
+++ b/drivers/watchdog/stm32_iwdg.c
@@ -0,0 +1,289 @@
+/*
+ * Driver for STM32 Independent Watchdog
+ *
+ * Copyright (C) Yannick Fertre 2017
+ * Author: Yannick Fertre <yannick.fertre@st.com>
+ *
+ * This driver is based on tegra_wdt.c
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+/* minimum watchdog trigger timeout, in seconds */
+#define MIN_WDT_TIMEOUT	1
+
+/* IWDG registers */
+#define IWDG_KR		0x00 /* Key register */
+#define IWDG_PR		0x04 /* Prescaler Register */
+#define IWDG_RLR	0x08 /* ReLoad Register */
+#define IWDG_SR		0x0C /* Status Register */
+#define IWDG_WINR	0x10 /* Windows Register */
+
+/* IWDG_KR register bit mask */
+#define KR_KEY_RELOAD	0xAAAA /* reload counter enable */
+#define KR_KEY_ENABLE	0xCCCC /* peripheral enable */
+#define KR_KEY_EWA	0x5555 /* write access enable */
+#define KR_KEY_DWA	0x0000 /* write access disable */
+
+/* IWDG_PR register bit values */
+#define PR_4    0x00 /* prescaler set to 4 */
+#define PR_8    0x01 /* prescaler set to 8 */
+#define PR_16   0x02 /* prescaler set to 16 */
+#define PR_32   0x03 /* prescaler set to 32 */
+#define PR_64   0x04 /* prescaler set to 64 */
+#define PR_128  0x05 /* prescaler set to 128 */
+#define PR_256	0x06 /* prescaler set to 256 */
+
+/* IWDG_RLR register values */
+#define RLR_MAX		0xFFF /* max value supported by reload register */
+
+/* IWDG_SR register bit mask */
+#define FLAG_PVU	BIT(0) /* Watchdog prescaler value update */
+#define FLAG_RVU	BIT(1) /* Watchdog counter reload value update */
+
+/* set timeout to 100000 us */
+#define TIMEOUT_US	100000
+#define SLEEP_US	1000
+
+struct stm32_iwdg {
+	struct watchdog_device	wdd;
+	struct device		*dev;
+	void __iomem		*regs;
+	struct clk		*clk;
+	unsigned int		rate;
+};
+
+static int heartbeat = MIN_WDT_TIMEOUT;
+module_param(heartbeat, int, 0x0);
+MODULE_PARM_DESC(heartbeat,
+		 "Watchdog heartbeats in seconds. (default = "
+		 __MODULE_STRING(WDT_HEARTBEAT) ")");
+
+static inline u32 reg_read(void __iomem *base, u32 reg)
+{
+	return readl_relaxed(base + reg);
+}
+
+static inline void reg_write(void __iomem *base, u32 reg, u32 val)
+{
+	writel_relaxed(val, base + reg);
+}
+
+static int stm32_iwdg_start(struct watchdog_device *wdd)
+{
+	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
+	u32 val = FLAG_PVU | FLAG_RVU;
+	u32 reload;
+	int ret;
+
+	dev_dbg(wdt->dev, "%s\n", __func__);
+
+	/* prescaler fixed to 256 */
+	reload = (wdd->timeout * wdt->rate) / 256;
+	if (reload > RLR_MAX + 1) {
+		dev_err(wdt->dev,
+			"Watchdog doesn't support reload value: %d\n", reload);
+		return -EINVAL;
+	}
+
+	/* enable watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
+
+	/* set prescaler & reload registers */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
+	reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */
+	reg_write(wdt->regs, IWDG_RLR, reload - 1);
+
+	/* wait for the registers to be updated (max 100ms) */
+	ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, val,
+					 !(val & (FLAG_PVU | FLAG_RVU)),
+					 SLEEP_US, TIMEOUT_US);
+	if (ret) {
+		dev_err(wdt->dev,
+			"Fail to set prescaler or reload registers\n");
+		return -EINVAL;
+	}
+
+	/* reload watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
+
+	return 0;
+}
+
+static int stm32_iwdg_stop(struct watchdog_device *wdd)
+{
+	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
+
+	if (watchdog_active(wdd)) {
+		dev_err(wdt->dev,
+			"Watchdog can't be stopped once started(no way out)\n");
+		return -EPERM;
+	}
+
+	return 0;
+}
+
+static int stm32_iwdg_ping(struct watchdog_device *wdd)
+{
+	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
+
+	dev_dbg(wdt->dev, "%s\n", __func__);
+
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
+
+	return 0;
+}
+
+static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
+				  unsigned int timeout)
+{
+	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
+
+	dev_dbg(wdt->dev, "%s timeout: %d sec\n", __func__, timeout);
+
+	wdd->timeout = timeout;
+
+	if (watchdog_active(wdd))
+		return stm32_iwdg_start(wdd);
+
+	return 0;
+}
+
+static const struct watchdog_info stm32_iwdg_info = {
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_MAGICCLOSE |
+			  WDIOF_KEEPALIVEPING,
+	.identity	= "STM32 Independent Watchdog",
+};
+
+static struct watchdog_ops stm32_iwdg_ops = {
+	.owner		= THIS_MODULE,
+	.start		= stm32_iwdg_start,
+	.stop		= stm32_iwdg_stop,
+	.ping		= stm32_iwdg_ping,
+	.set_timeout	= stm32_iwdg_set_timeout,
+};
+
+static int stm32_iwdg_probe(struct platform_device *pdev)
+{
+	struct watchdog_device *wdd;
+	struct stm32_iwdg *wdt;
+	struct resource *res;
+	void __iomem *regs;
+	struct clk *clk;
+	int max_wdt_timeout;
+	int ret;
+
+	/* This is the timer base. */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(regs)) {
+		dev_err(&pdev->dev, "Could not get resource\n");
+		return PTR_ERR(regs);
+	}
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "Unable to get clock\n");
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to prepare clock %p\n", clk);
+		return ret;
+	}
+
+	/*
+	 * Allocate our watchdog driver data, which has the
+	 * struct watchdog_device nested within it.
+	 */
+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	/* Initialize struct stm32_iwdg. */
+	wdt->regs = regs;
+	wdt->dev = &pdev->dev;
+	wdt->clk = clk;
+	/*
+	 * iwdg is clocked by its own dedicated low-speed clock (LSI)
+	 * at 32khz.
+	 */
+	wdt->rate = 32 * 1024;
+
+	/* get max timeout & set heartbeat */
+	max_wdt_timeout = ((RLR_MAX + 1) * 256) / wdt->rate;
+	heartbeat = max_wdt_timeout;
+
+	/* Initialize struct watchdog_device. */
+	wdd = &wdt->wdd;
+	wdd->timeout = heartbeat;
+	wdd->info = &stm32_iwdg_info;
+	wdd->ops = &stm32_iwdg_ops;
+	wdd->min_timeout = MIN_WDT_TIMEOUT;
+	wdd->max_timeout = max_wdt_timeout;
+	watchdog_set_drvdata(wdd, wdt);
+	watchdog_set_nowayout(wdd, true);
+
+	ret = watchdog_register_device(wdd);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"failed to register watchdog device\n");
+		goto err;
+	}
+
+	platform_set_drvdata(pdev, wdt);
+
+	dev_info(&pdev->dev,
+		 "initialized (heartbeat = %d sec)\n", heartbeat);
+	return 0;
+
+err:
+	clk_disable_unprepare(clk);
+	return ret;
+}
+
+static int stm32_iwdg_remove(struct platform_device *pdev)
+{
+	struct stm32_iwdg *wdt = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&wdt->wdd);
+	clk_disable_unprepare(wdt->clk);
+
+	dev_info(&pdev->dev, "removed watchdog device\n");
+	return 0;
+}
+
+static const struct of_device_id stm32_iwdg_of_match[] = {
+	{ .compatible = "st,stm32-iwdg" },
+	{ /* end node */ }
+};
+MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match);
+
+static struct platform_driver stm32_iwdg_driver = {
+	.probe		= stm32_iwdg_probe,
+	.remove		= stm32_iwdg_remove,
+	.driver = {
+		.name	= "iwdg",
+		.of_match_table = stm32_iwdg_of_match,
+	},
+};
+module_platform_driver(stm32_iwdg_driver);
+
+MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

[PATCH v3 3/5] ARM: dts: stm32: Add watchdog support for STM32F429 SoC

[Yannick Fertre]

Add watchdog into DT for stm32f429 family.

Signed-off-by: Yannick FERTRE <yannick.fertre@st.com>
---
 arch/arm/boot/dts/stm32f429.dtsi | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/stm32f429.dtsi b/arch/arm/boot/dts/stm32f429.dtsi
index ee0da97..9b71dde 100644
--- a/arch/arm/boot/dts/stm32f429.dtsi
+++ b/arch/arm/boot/dts/stm32f429.dtsi
@@ -65,7 +65,7 @@
 			clock-frequency = <32768>;
 		};
 
-		clk-lsi {
+		clk_lsi: clk-lsi {
 			#clock-cells = <0>;
 			compatible = "fixed-clock";
 			clock-frequency = <32000>;
@@ -307,6 +307,13 @@
 			status = "disabled";
 		};
 
+		iwdg: iwdg@40003000 {
+			compatible = "st,stm32-iwdg";
+			reg = <0x40003000 0x400>;
+			clocks = <&clk_lsi>;
+			status = "disabled";
+		};
+
 		usart2: serial@40004400 {
 			compatible = "st,stm32-usart", "st,stm32-uart";
 			reg = <0x40004400 0x400>;
-- 
1.9.1

[PATCH v3 4/5] ARM: dts: stm32: Add watchdog support for STM32F429 eval board

[Yannick Fertre]

This patch adds watchdog support for STM32x9I-Eval board.

Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
---
 arch/arm/boot/dts/stm32429i-eval.dts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/stm32429i-eval.dts b/arch/arm/boot/dts/stm32429i-eval.dts
index 3c99466..1c7d0b9 100644
--- a/arch/arm/boot/dts/stm32429i-eval.dts
+++ b/arch/arm/boot/dts/stm32429i-eval.dts
@@ -126,6 +126,10 @@
 	};
 };
 
+&iwdg {
+	status = "okay";
+};
+
 &adc {
 	pinctrl-names = "default";
 	pinctrl-0 = <&adc3_in8_pin>;
-- 
1.9.1

[PATCH v3 5/5] ARM: configs: Add watchdog support in STM32 defconfig

[Yannick Fertre]

This patch adds STM32 watchdog support in stm32_defconfig file

Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
---
 arch/arm/configs/stm32_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/stm32_defconfig b/arch/arm/configs/stm32_defconfig
index a9d8e3c..83afa73 100644
--- a/arch/arm/configs/stm32_defconfig
+++ b/arch/arm/configs/stm32_defconfig
@@ -48,6 +48,7 @@ CONFIG_SERIAL_STM32=y
 CONFIG_SERIAL_STM32_CONSOLE=y
 # CONFIG_HW_RANDOM is not set
 # CONFIG_HWMON is not set
+CONFIG_WATCHDOG=y
 CONFIG_REGULATOR=y
 CONFIG_REGULATOR_FIXED_VOLTAGE=y
 # CONFIG_USB_SUPPORT is not set
-- 
1.9.1

Re: [PATCH v3 5/5] ARM: configs: Add watchdog support in STM32 defconfig

[Alexandre Torgue]

Hi,

On 03/22/2017 04:04 PM, Yannick Fertre wrote:
> This patch adds STM32 watchdog support in stm32_defconfig file
>
> Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
> ---

Update commit header please (ARM: configs: stm32: Add watchdog support)

>  arch/arm/configs/stm32_defconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/configs/stm32_defconfig b/arch/arm/configs/stm32_defconfig
> index a9d8e3c..83afa73 100644
> --- a/arch/arm/configs/stm32_defconfig
> +++ b/arch/arm/configs/stm32_defconfig
> @@ -48,6 +48,7 @@ CONFIG_SERIAL_STM32=y
>  CONFIG_SERIAL_STM32_CONSOLE=y
>  # CONFIG_HW_RANDOM is not set
>  # CONFIG_HWMON is not set
> +CONFIG_WATCHDOG=y
>  CONFIG_REGULATOR=y
>  CONFIG_REGULATOR_FIXED_VOLTAGE=y
>  # CONFIG_USB_SUPPORT is not set
>

Re: [PATCH v3 1/5] dt-bindings: Document STM32 IWDG bindings

[Rob Herring]

On Wed, Mar 22, 2017 at 04:04:39PM +0100, Yannick Fertre wrote:
> From: Yannick Fertre <yfertre.stm32@gmail.com>

"dt-bindings: watchdog: ..." for subject.
> 
> This adds documentation of device tree bindings for the STM32 IWDG
> (Independent WatchDoG).
> 
> Change-Id: Idadacc806d00205fe9af2e8606af229b4b760558
> Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
> ---
>  .../devicetree/bindings/watchdog/st,stm32-iwdg.txt        | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt b/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
> new file mode 100644
> index 0000000..036b040
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
> @@ -0,0 +1,15 @@
> +STM32 Independent WatchDoG (IWDG)
> +---------------------------------
> +
> +Required properties:
> +- compatible: "st,stm32-iwdg"
> +- reg: physical base address and length of the registers set for the device
> +- clocks: must contain a single entry describing the clock input
> +
> +Example:
> +
> +iwdg@40003000 {

watchdog@...

> +	compatible = "st,stm32-iwdg";
> +	reg = <0x40003000 0x400>;
> +	clocks = <&clk_lsi>;
> +};
> -- 
> 1.9.1
> 

Re: [PATCH v3 0/5] STM32 Independant watchdog

[Guenter Roeck]

Subject: s/Independant/Independent/

On 03/22/2017 08:04 AM, Yannick Fertre wrote:
> Version 3:
> - Update typo into  bindings file
> - Reorder node in devicetree (ordering by address)
> - Remove unecessary lines in commits
>
> Version 2:
> - Add commit messages
>
> Version 1:
> - Initial commit
>
> The purpose of this set of patches is to add a new watchdog driver for
> stm32f429.
> This driver was developed and tested on evaluation board stm32429i.
>
> Yannick Fertre (5):
>   dt-bindings: Document STM32 IWDG bindings
>   drivers: watchdog: Add STM32 IWDG driver
>   ARM: dts: stm32: Add watchdog support for STM32F429 SoC
>   ARM: dts: stm32: Add watchdog support for STM32F429 eval board
>   ARM: configs: Add watchdog support in STM32 defconfig
>
>  .../devicetree/bindings/watchdog/st,stm32-iwdg.txt |  15 ++
>  arch/arm/boot/dts/stm32429i-eval.dts               |   4 +
>  arch/arm/boot/dts/stm32f429.dtsi                   |   9 +-
>  arch/arm/configs/stm32_defconfig                   |   1 +
>  drivers/watchdog/Kconfig                           |  11 +
>  drivers/watchdog/Makefile                          |   1 +
>  drivers/watchdog/stm32_iwdg.c                      | 289 +++++++++++++++++++++
>  7 files changed, 329 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
>  create mode 100644 drivers/watchdog/stm32_iwdg.c
>

Re: [PATCH v3 2/5] drivers: watchdog: Add STM32 IWDG driver

[Guenter Roeck]

On 03/22/2017 08:04 AM, Yannick Fertre wrote:
> This patch adds IWDG (Independent WatchDoG) support for STM32 platform.
>
> Change-Id: Iab218745fc25566f12558fae7f52e2f8c21db74e

No gerrit tags, please.

> Signed-off-by: Yannick FERTRE <yannick.fertre@st.com>
> ---
>  drivers/watchdog/Kconfig      |  11 ++
>  drivers/watchdog/Makefile     |   1 +
>  drivers/watchdog/stm32_iwdg.c | 289 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 301 insertions(+)
>  create mode 100644 drivers/watchdog/stm32_iwdg.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 52a70ee..d9745a5 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -744,6 +744,17 @@ config ZX2967_WATCHDOG
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called zx2967_wdt.
>
> +config STM32_WATCHDOG
> +	tristate "STM32 Independent WatchDoG (IWDG) support"
> +	depends on ARCH_STM32
> +	select WATCHDOG_CORE
> +	default y
> +	help
> +	  Say Y here to include Watchdog timer support.

... for <pick your text>.

> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called stm32_iwdg.
> +
>  # AVR32 Architecture
>
>  config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index a2126e2..a35e423 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
>  obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
>  obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
>  obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
> +obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
>
>  # AVR32 Architecture
>  obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c
> new file mode 100644
> index 0000000..507dfc4
> --- /dev/null
> +++ b/drivers/watchdog/stm32_iwdg.c
> @@ -0,0 +1,289 @@
> +/*
> + * Driver for STM32 Independent Watchdog
> + *
> + * Copyright (C) Yannick Fertre 2017
> + * Author: Yannick Fertre <yannick.fertre@st.com>
> + *
> + * This driver is based on tegra_wdt.c
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +/* minimum watchdog trigger timeout, in seconds */
> +#define MIN_WDT_TIMEOUT	1
> +
> +/* IWDG registers */
> +#define IWDG_KR		0x00 /* Key register */
> +#define IWDG_PR		0x04 /* Prescaler Register */
> +#define IWDG_RLR	0x08 /* ReLoad Register */
> +#define IWDG_SR		0x0C /* Status Register */
> +#define IWDG_WINR	0x10 /* Windows Register */
> +
> +/* IWDG_KR register bit mask */
> +#define KR_KEY_RELOAD	0xAAAA /* reload counter enable */
> +#define KR_KEY_ENABLE	0xCCCC /* peripheral enable */
> +#define KR_KEY_EWA	0x5555 /* write access enable */
> +#define KR_KEY_DWA	0x0000 /* write access disable */
> +
> +/* IWDG_PR register bit values */
> +#define PR_4    0x00 /* prescaler set to 4 */
> +#define PR_8    0x01 /* prescaler set to 8 */
> +#define PR_16   0x02 /* prescaler set to 16 */
> +#define PR_32   0x03 /* prescaler set to 32 */
> +#define PR_64   0x04 /* prescaler set to 64 */
> +#define PR_128  0x05 /* prescaler set to 128 */
> +#define PR_256	0x06 /* prescaler set to 256 */
> +
> +/* IWDG_RLR register values */
> +#define RLR_MAX		0xFFF /* max value supported by reload register */
> +
> +/* IWDG_SR register bit mask */
> +#define FLAG_PVU	BIT(0) /* Watchdog prescaler value update */
> +#define FLAG_RVU	BIT(1) /* Watchdog counter reload value update */
> +
> +/* set timeout to 100000 us */
> +#define TIMEOUT_US	100000
> +#define SLEEP_US	1000
> +
> +struct stm32_iwdg {
> +	struct watchdog_device	wdd;
> +	struct device		*dev;
> +	void __iomem		*regs;
> +	struct clk		*clk;
> +	unsigned int		rate;
> +};
> +
> +static int heartbeat = MIN_WDT_TIMEOUT;
> +module_param(heartbeat, int, 0x0);
> +MODULE_PARM_DESC(heartbeat,
> +		 "Watchdog heartbeats in seconds. (default = "
> +		 __MODULE_STRING(WDT_HEARTBEAT) ")");
> +
> +static inline u32 reg_read(void __iomem *base, u32 reg)
> +{
> +	return readl_relaxed(base + reg);
> +}
> +
> +static inline void reg_write(void __iomem *base, u32 reg, u32 val)
> +{
> +	writel_relaxed(val, base + reg);
> +}
> +
> +static int stm32_iwdg_start(struct watchdog_device *wdd)
> +{
> +	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
> +	u32 val = FLAG_PVU | FLAG_RVU;
> +	u32 reload;
> +	int ret;
> +
> +	dev_dbg(wdt->dev, "%s\n", __func__);
> +
> +	/* prescaler fixed to 256 */
> +	reload = (wdd->timeout * wdt->rate) / 256;
> +	if (reload > RLR_MAX + 1) {
> +		dev_err(wdt->dev,
> +			"Watchdog doesn't support reload value: %d\n", reload);
> +		return -EINVAL;
> +	}

This should not happen if min_timeout and max_timeout are set properly.

> +
> +	/* enable watchdog */
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
> +
> +	/* set prescaler & reload registers */
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
> +	reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */
> +	reg_write(wdt->regs, IWDG_RLR, reload - 1);
> +
> +	/* wait for the registers to be updated (max 100ms) */
> +	ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, val,
> +					 !(val & (FLAG_PVU | FLAG_RVU)),
> +					 SLEEP_US, TIMEOUT_US);
> +	if (ret) {
> +		dev_err(wdt->dev,
> +			"Fail to set prescaler or reload registers\n");
> +		return -EINVAL;

Any reason for overriding the return value ?

> +	}
> +
> +	/* reload watchdog */
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
> +
> +	return 0;
> +}
> +
> +static int stm32_iwdg_stop(struct watchdog_device *wdd)
> +{
> +	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
> +
> +	if (watchdog_active(wdd)) {
> +		dev_err(wdt->dev,
> +			"Watchdog can't be stopped once started(no way out)\n");
> +		return -EPERM;

The infrastructure takes care of this. Don't provide a stop function, and provide
the maximum hardware timeout.

> +	}
> +
> +	return 0;
> +}
> +
> +static int stm32_iwdg_ping(struct watchdog_device *wdd)
> +{
> +	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
> +
> +	dev_dbg(wdt->dev, "%s\n", __func__);
> +
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
> +
> +	return 0;
> +}
> +
> +static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
> +				  unsigned int timeout)
> +{
> +	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
> +
> +	dev_dbg(wdt->dev, "%s timeout: %d sec\n", __func__, timeout);
> +
> +	wdd->timeout = timeout;
> +
> +	if (watchdog_active(wdd))
> +		return stm32_iwdg_start(wdd);
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info stm32_iwdg_info = {
> +	.options	= WDIOF_SETTIMEOUT |
> +			  WDIOF_MAGICCLOSE |
> +			  WDIOF_KEEPALIVEPING,
> +	.identity	= "STM32 Independent Watchdog",
> +};
> +
> +static struct watchdog_ops stm32_iwdg_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= stm32_iwdg_start,
> +	.stop		= stm32_iwdg_stop,
> +	.ping		= stm32_iwdg_ping,
> +	.set_timeout	= stm32_iwdg_set_timeout,
> +};
> +
> +static int stm32_iwdg_probe(struct platform_device *pdev)
> +{
> +	struct watchdog_device *wdd;
> +	struct stm32_iwdg *wdt;
> +	struct resource *res;
> +	void __iomem *regs;
> +	struct clk *clk;
> +	int max_wdt_timeout;
> +	int ret;
> +
> +	/* This is the timer base. */
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(regs)) {
> +		dev_err(&pdev->dev, "Could not get resource\n");
> +		return PTR_ERR(regs);
> +	}
> +
> +	clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk)) {
> +		dev_err(&pdev->dev, "Unable to get clock\n");
> +		return PTR_ERR(clk);
> +	}
> +
> +	ret = clk_prepare_enable(clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Unable to prepare clock %p\n", clk);
> +		return ret;
> +	}
> +
> +	/*
> +	 * Allocate our watchdog driver data, which has the
> +	 * struct watchdog_device nested within it.
> +	 */
> +	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> +	if (!wdt) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	/* Initialize struct stm32_iwdg. */
> +	wdt->regs = regs;
> +	wdt->dev = &pdev->dev;
> +	wdt->clk = clk;
> +	/*
> +	 * iwdg is clocked by its own dedicated low-speed clock (LSI)
> +	 * at 32khz.
> +	 */
> +	wdt->rate = 32 * 1024;

Why not clk_get_rate() ?

> +
> +	/* get max timeout & set heartbeat */
> +	max_wdt_timeout = ((RLR_MAX + 1) * 256) / wdt->rate;
> +	heartbeat = max_wdt_timeout;

What is the value of overwriting this variable ? Why don't you just use max_wdt_timeout,
and what is the point of making heartbeat configurable if you overwrite it anyway ?

I would suggest to use watchdog_init_timeout() to set optional non-default
timeout values, especially since this also enables getting the timeout value from
devicetree.

> +
> +	/* Initialize struct watchdog_device. */
> +	wdd = &wdt->wdd;
> +	wdd->timeout = heartbeat;
> +	wdd->info = &stm32_iwdg_info;
> +	wdd->ops = &stm32_iwdg_ops;
> +	wdd->min_timeout = MIN_WDT_TIMEOUT;
> +	wdd->max_timeout = max_wdt_timeout;

You might want to consider setting max_hw_heartbeat_ms instead and drop the stop function.

> +	watchdog_set_drvdata(wdd, wdt);
> +	watchdog_set_nowayout(wdd, true);
> +
> +	ret = watchdog_register_device(wdd);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"failed to register watchdog device\n");
> +		goto err;
> +	}
> +
> +	platform_set_drvdata(pdev, wdt);
> +
> +	dev_info(&pdev->dev,
> +		 "initialized (heartbeat = %d sec)\n", heartbeat);
> +	return 0;
> +
> +err:
> +	clk_disable_unprepare(clk);
> +	return ret;
> +}
> +
> +static int stm32_iwdg_remove(struct platform_device *pdev)
> +{
> +	struct stm32_iwdg *wdt = platform_get_drvdata(pdev);
> +
> +	watchdog_unregister_device(&wdt->wdd);
> +	clk_disable_unprepare(wdt->clk);
> +
> +	dev_info(&pdev->dev, "removed watchdog device\n");

Is this message really useful ? I think it is just noise.

> +	return 0;
> +}
> +
> +static const struct of_device_id stm32_iwdg_of_match[] = {
> +	{ .compatible = "st,stm32-iwdg" },
> +	{ /* end node */ }
> +};
> +MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match);
> +
> +static struct platform_driver stm32_iwdg_driver = {
> +	.probe		= stm32_iwdg_probe,
> +	.remove		= stm32_iwdg_remove,
> +	.driver = {
> +		.name	= "iwdg",
> +		.of_match_table = stm32_iwdg_of_match,
> +	},
> +};
> +module_platform_driver(stm32_iwdg_driver);
> +
> +MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>");
> +MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog Driver");
> +MODULE_LICENSE("GPL v2");
>

Re: [PATCH v3 1/5] dt-bindings: Document STM32 IWDG bindings

[Guenter Roeck]

On 03/22/2017 08:04 AM, Yannick Fertre wrote:
> From: Yannick Fertre <yfertre.stm32@gmail.com>
>
> This adds documentation of device tree bindings for the STM32 IWDG
> (Independent WatchDoG).
>
> Change-Id: Idadacc806d00205fe9af2e8606af229b4b760558

Please drop.

> Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
> ---
>  .../devicetree/bindings/watchdog/st,stm32-iwdg.txt        | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
>
> diff --git a/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt b/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
> new file mode 100644
> index 0000000..036b040
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/st,stm32-iwdg.txt
> @@ -0,0 +1,15 @@
> +STM32 Independent WatchDoG (IWDG)
> +---------------------------------
> +
> +Required properties:
> +- compatible: "st,stm32-iwdg"
> +- reg: physical base address and length of the registers set for the device
> +- clocks: must contain a single entry describing the clock input
> +
> +Example:
> +
> +iwdg@40003000 {
> +	compatible = "st,stm32-iwdg";
> +	reg = <0x40003000 0x400>;
> +	clocks = <&clk_lsi>;
> +};
>

Re: [PATCH v3 2/5] drivers: watchdog: Add STM32 IWDG driver

[Yannick FERTRE]

Hi Guenter,
Many thanks for your help, I will push corrections to V4.

Best regards


On 03/29/2017 05:15 AM, Guenter Roeck wrote:
> On 03/22/2017 08:04 AM, Yannick Fertre wrote:
>> This patch adds IWDG (Independent WatchDoG) support for STM32 platform.
>>
>> Change-Id: Iab218745fc25566f12558fae7f52e2f8c21db74e
>
> No gerrit tags, please.
>
>> Signed-off-by: Yannick FERTRE <yannick.fertre@st.com>
>> ---
>>  drivers/watchdog/Kconfig      |  11 ++
>>  drivers/watchdog/Makefile     |   1 +
>>  drivers/watchdog/stm32_iwdg.c | 289
>> ++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 301 insertions(+)
>>  create mode 100644 drivers/watchdog/stm32_iwdg.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 52a70ee..d9745a5 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -744,6 +744,17 @@ config ZX2967_WATCHDOG
>>        To compile this driver as a module, choose M here: the
>>        module will be called zx2967_wdt.
>>
>> +config STM32_WATCHDOG
>> +    tristate "STM32 Independent WatchDoG (IWDG) support"
>> +    depends on ARCH_STM32
>> +    select WATCHDOG_CORE
>> +    default y
>> +    help
>> +      Say Y here to include Watchdog timer support.
>
> ... for <pick your text>.
Ok done
>
>> +
>> +      To compile this driver as a module, choose M here: the
>> +      module will be called stm32_iwdg.
>> +
>>  # AVR32 Architecture
>>
>>  config AT32AP700X_WDT
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index a2126e2..a35e423 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -84,6 +84,7 @@ obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
>>  obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
>>  obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
>>  obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
>> +obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
>>
>>  # AVR32 Architecture
>>  obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
>> diff --git a/drivers/watchdog/stm32_iwdg.c
>> b/drivers/watchdog/stm32_iwdg.c
>> new file mode 100644
>> index 0000000..507dfc4
>> --- /dev/null
>> +++ b/drivers/watchdog/stm32_iwdg.c
>> @@ -0,0 +1,289 @@
>> +/*
>> + * Driver for STM32 Independent Watchdog
>> + *
>> + * Copyright (C) Yannick Fertre 2017
>> + * Author: Yannick Fertre <yannick.fertre@st.com>
>> + *
>> + * This driver is based on tegra_wdt.c
>> + *
>> + * License terms:  GNU General Public License (GPL), version 2
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/watchdog.h>
>> +
>> +/* minimum watchdog trigger timeout, in seconds */
>> +#define MIN_WDT_TIMEOUT    1
>> +
>> +/* IWDG registers */
>> +#define IWDG_KR        0x00 /* Key register */
>> +#define IWDG_PR        0x04 /* Prescaler Register */
>> +#define IWDG_RLR    0x08 /* ReLoad Register */
>> +#define IWDG_SR        0x0C /* Status Register */
>> +#define IWDG_WINR    0x10 /* Windows Register */
>> +
>> +/* IWDG_KR register bit mask */
>> +#define KR_KEY_RELOAD    0xAAAA /* reload counter enable */
>> +#define KR_KEY_ENABLE    0xCCCC /* peripheral enable */
>> +#define KR_KEY_EWA    0x5555 /* write access enable */
>> +#define KR_KEY_DWA    0x0000 /* write access disable */
>> +
>> +/* IWDG_PR register bit values */
>> +#define PR_4    0x00 /* prescaler set to 4 */
>> +#define PR_8    0x01 /* prescaler set to 8 */
>> +#define PR_16   0x02 /* prescaler set to 16 */
>> +#define PR_32   0x03 /* prescaler set to 32 */
>> +#define PR_64   0x04 /* prescaler set to 64 */
>> +#define PR_128  0x05 /* prescaler set to 128 */
>> +#define PR_256    0x06 /* prescaler set to 256 */
>> +
>> +/* IWDG_RLR register values */
>> +#define RLR_MAX        0xFFF /* max value supported by reload
>> register */
>> +
>> +/* IWDG_SR register bit mask */
>> +#define FLAG_PVU    BIT(0) /* Watchdog prescaler value update */
>> +#define FLAG_RVU    BIT(1) /* Watchdog counter reload value update */
>> +
>> +/* set timeout to 100000 us */
>> +#define TIMEOUT_US    100000
>> +#define SLEEP_US    1000
>> +
>> +struct stm32_iwdg {
>> +    struct watchdog_device    wdd;
>> +    struct device        *dev;
>> +    void __iomem        *regs;
>> +    struct clk        *clk;
>> +    unsigned int        rate;
>> +};
>> +
>> +static int heartbeat = MIN_WDT_TIMEOUT;
>> +module_param(heartbeat, int, 0x0);
>> +MODULE_PARM_DESC(heartbeat,
>> +         "Watchdog heartbeats in seconds. (default = "
>> +         __MODULE_STRING(WDT_HEARTBEAT) ")");
>> +
>> +static inline u32 reg_read(void __iomem *base, u32 reg)
>> +{
>> +    return readl_relaxed(base + reg);
>> +}
>> +
>> +static inline void reg_write(void __iomem *base, u32 reg, u32 val)
>> +{
>> +    writel_relaxed(val, base + reg);
>> +}
>> +
>> +static int stm32_iwdg_start(struct watchdog_device *wdd)
>> +{
>> +    struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
>> +    u32 val = FLAG_PVU | FLAG_RVU;
>> +    u32 reload;
>> +    int ret;
>> +
>> +    dev_dbg(wdt->dev, "%s\n", __func__);
>> +
>> +    /* prescaler fixed to 256 */
>> +    reload = (wdd->timeout * wdt->rate) / 256;
>> +    if (reload > RLR_MAX + 1) {
>> +        dev_err(wdt->dev,
>> +            "Watchdog doesn't support reload value: %d\n", reload);
>> +        return -EINVAL;
>> +    }
>
> This should not happen if min_timeout and max_timeout are set properly.
>
Ok, I remove the test.
>> +
>> +    /* enable watchdog */
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
>> +
>> +    /* set prescaler & reload registers */
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
>> +    reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */
>> +    reg_write(wdt->regs, IWDG_RLR, reload - 1);
>> +
>> +    /* wait for the registers to be updated (max 100ms) */
>> +    ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, val,
>> +                     !(val & (FLAG_PVU | FLAG_RVU)),
>> +                     SLEEP_US, TIMEOUT_US);
>> +    if (ret) {
>> +        dev_err(wdt->dev,
>> +            "Fail to set prescaler or reload registers\n");
>> +        return -EINVAL;
>
> Any reason for overriding the return value ?
>
Ok, done
>> +    }
>> +
>> +    /* reload watchdog */
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
>> +
>> +    return 0;
>> +}
>> +
>> +static int stm32_iwdg_stop(struct watchdog_device *wdd)
>> +{
>> +    struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
>> +
>> +    if (watchdog_active(wdd)) {
>> +        dev_err(wdt->dev,
>> +            "Watchdog can't be stopped once started(no way out)\n");
>> +        return -EPERM;
>
> The infrastructure takes care of this. Don't provide a stop function,
> and provide
> the maximum hardware timeout.
Ok, I remove stop function
>
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int stm32_iwdg_ping(struct watchdog_device *wdd)
>> +{
>> +    struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
>> +
>> +    dev_dbg(wdt->dev, "%s\n", __func__);
>> +
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
>> +
>> +    return 0;
>> +}
>> +
>> +static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
>> +                  unsigned int timeout)
>> +{
>> +    struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
>> +
>> +    dev_dbg(wdt->dev, "%s timeout: %d sec\n", __func__, timeout);
>> +
>> +    wdd->timeout = timeout;
>> +
>> +    if (watchdog_active(wdd))
>> +        return stm32_iwdg_start(wdd);
>> +
>> +    return 0;
>> +}
>> +
>> +static const struct watchdog_info stm32_iwdg_info = {
>> +    .options    = WDIOF_SETTIMEOUT |
>> +              WDIOF_MAGICCLOSE |
>> +              WDIOF_KEEPALIVEPING,
>> +    .identity    = "STM32 Independent Watchdog",
>> +};
>> +
>> +static struct watchdog_ops stm32_iwdg_ops = {
>> +    .owner        = THIS_MODULE,
>> +    .start        = stm32_iwdg_start,
>> +    .stop        = stm32_iwdg_stop,
>> +    .ping        = stm32_iwdg_ping,
>> +    .set_timeout    = stm32_iwdg_set_timeout,
>> +};
>> +
>> +static int stm32_iwdg_probe(struct platform_device *pdev)
>> +{
>> +    struct watchdog_device *wdd;
>> +    struct stm32_iwdg *wdt;
>> +    struct resource *res;
>> +    void __iomem *regs;
>> +    struct clk *clk;
>> +    int max_wdt_timeout;
>> +    int ret;
>> +
>> +    /* This is the timer base. */
>> +    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +    regs = devm_ioremap_resource(&pdev->dev, res);
>> +    if (IS_ERR(regs)) {
>> +        dev_err(&pdev->dev, "Could not get resource\n");
>> +        return PTR_ERR(regs);
>> +    }
>> +
>> +    clk = devm_clk_get(&pdev->dev, NULL);
>> +    if (IS_ERR(clk)) {
>> +        dev_err(&pdev->dev, "Unable to get clock\n");
>> +        return PTR_ERR(clk);
>> +    }
>> +
>> +    ret = clk_prepare_enable(clk);
>> +    if (ret) {
>> +        dev_err(&pdev->dev, "Unable to prepare clock %p\n", clk);
>> +        return ret;
>> +    }
>> +
>> +    /*
>> +     * Allocate our watchdog driver data, which has the
>> +     * struct watchdog_device nested within it.
>> +     */
>> +    wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
>> +    if (!wdt) {
>> +        ret = -ENOMEM;
>> +        goto err;
>> +    }
>> +
>> +    /* Initialize struct stm32_iwdg. */
>> +    wdt->regs = regs;
>> +    wdt->dev = &pdev->dev;
>> +    wdt->clk = clk;
>> +    /*
>> +     * iwdg is clocked by its own dedicated low-speed clock (LSI)
>> +     * at 32khz.
>> +     */
>> +    wdt->rate = 32 * 1024;
>
> Why not clk_get_rate() ?
Ok, done
>
>> +
>> +    /* get max timeout & set heartbeat */
>> +    max_wdt_timeout = ((RLR_MAX + 1) * 256) / wdt->rate;
>> +    heartbeat = max_wdt_timeout;
>
> What is the value of overwriting this variable ? Why don't you just use
> max_wdt_timeout,
> and what is the point of making heartbeat configurable if you overwrite
> it anyway ?
>
> I would suggest to use watchdog_init_timeout() to set optional non-default
> timeout values, especially since this also enables getting the timeout
> value from
> devicetree.
>
Ok done
>> +
>> +    /* Initialize struct watchdog_device. */
>> +    wdd = &wdt->wdd;
>> +    wdd->timeout = heartbeat;
>> +    wdd->info = &stm32_iwdg_info;
>> +    wdd->ops = &stm32_iwdg_ops;
>> +    wdd->min_timeout = MIN_WDT_TIMEOUT;
>> +    wdd->max_timeout = max_wdt_timeout;
>
> You might want to consider setting max_hw_heartbeat_ms instead and drop
> the stop function.
>
Ok, done
>> +    watchdog_set_drvdata(wdd, wdt);
>> +    watchdog_set_nowayout(wdd, true);
>> +
>> +    ret = watchdog_register_device(wdd);
>> +    if (ret) {
>> +        dev_err(&pdev->dev,
>> +            "failed to register watchdog device\n");
>> +        goto err;
>> +    }
>> +
>> +    platform_set_drvdata(pdev, wdt);
>> +
>> +    dev_info(&pdev->dev,
>> +         "initialized (heartbeat = %d sec)\n", heartbeat);
>> +    return 0;
>> +
>> +err:
>> +    clk_disable_unprepare(clk);
>> +    return ret;
>> +}
>> +
>> +static int stm32_iwdg_remove(struct platform_device *pdev)
>> +{
>> +    struct stm32_iwdg *wdt = platform_get_drvdata(pdev);
>> +
>> +    watchdog_unregister_device(&wdt->wdd);
>> +    clk_disable_unprepare(wdt->clk);
>> +
>> +    dev_info(&pdev->dev, "removed watchdog device\n");
>
> Is this message really useful ? I think it is just noise.
Ok, removed
>
>> +    return 0;
>> +}
>> +
>> +static const struct of_device_id stm32_iwdg_of_match[] = {
>> +    { .compatible = "st,stm32-iwdg" },
>> +    { /* end node */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match);
>> +
>> +static struct platform_driver stm32_iwdg_driver = {
>> +    .probe        = stm32_iwdg_probe,
>> +    .remove        = stm32_iwdg_remove,
>> +    .driver = {
>> +        .name    = "iwdg",
>> +        .of_match_table = stm32_iwdg_of_match,
>> +    },
>> +};
>> +module_platform_driver(stm32_iwdg_driver);
>> +
>> +MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>");
>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog
>> Driver");
>> +MODULE_LICENSE("GPL v2");
>>
>