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[PATCH v4 2/5] drivers: watchdog: Add STM32 IWDG driver

Started byYannick Fertre <yannick.fertre@st.com>
First post2017-03-30 17:20 +0200
Last post2017-04-06 14:30 +0200
Articles 3 — 3 participants

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  [PATCH v4 2/5] drivers: watchdog: Add STM32 IWDG driver Yannick Fertre <yannick.fertre@st.com> - 2017-03-30 17:20 +0200
    Re: [PATCH v4 2/5] drivers: watchdog: Add STM32 IWDG driver Guenter Roeck <linux@roeck-us.net> - 2017-04-02 13:50 +0200
      Re: [PATCH v4 2/5] drivers: watchdog: Add STM32 IWDG driver Yannick FERTRE <yannick.fertre@st.com> - 2017-04-06 14:30 +0200

#1613158 — [PATCH v4 2/5] drivers: watchdog: Add STM32 IWDG driver

FromYannick Fertre <yannick.fertre@st.com>
Date2017-03-30 17:20 +0200
Subject[PATCH v4 2/5] drivers: watchdog: Add STM32 IWDG driver
Message-ID<tqK1H-8eB-9@gated-at.bofh.it>
This patch adds IWDG (Independent WatchDoG) support for STM32 platform.

Signed-off-by: Yannick FERTRE <yannick.fertre@st.com>
---
 drivers/watchdog/Kconfig      |  12 ++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/stm32_iwdg.c | 260 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 273 insertions(+)
 create mode 100644 drivers/watchdog/stm32_iwdg.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 52a70ee..d014deb 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -744,6 +744,18 @@ 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 support for the watchdog timer
+	  in stm32 SoCs.
+
+	  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..629c305
--- /dev/null
+++ b/drivers/watchdog/stm32_iwdg.c
@@ -0,0 +1,260 @@
+/*
+ * 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>
+
+/* watchdog trigger timeout, in seconds */
+#define WDT_MIN_TIMEOUT		1
+#define WDT_MAX_TIMEOUT		32
+#define WDT_DEFAULT_TIMEOUT	30
+
+/* 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;
+	void __iomem		*regs;
+	struct clk		*clk;
+	unsigned int		rate;
+};
+
+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(wdd->parent, "%s\n", __func__);
+
+	/* enable watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
+
+	/* prescaler fixed to 256 */
+	reload = (wdd->timeout * wdt->rate) / 256;
+	if (reload > RLR_MAX + 1)
+		reload = RLR_MAX + 1;
+
+	/* set prescaler & reload registers */
+	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(wdd->parent,
+			"Fail to set prescaler or reload registers\n");
+		return ret;
+	}
+
+	/* reload watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
+
+	return 0;
+}
+
+static int stm32_iwdg_ping(struct watchdog_device *wdd)
+{
+	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
+
+	dev_dbg(wdd->parent, "%s\n", __func__);
+
+	/* reload watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
+
+	return 0;
+}
+
+static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
+				  unsigned int timeout)
+{
+	dev_dbg(wdd->parent, "%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,
+	.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 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->clk = clk;
+	wdt->rate = clk_get_rate(clk);
+
+	/* Initialize struct watchdog_device. */
+	wdd = &wdt->wdd;
+	wdd->info = &stm32_iwdg_info;
+	wdd->ops = &stm32_iwdg_ops;
+	wdd->min_timeout = WDT_MIN_TIMEOUT;
+	wdd->max_timeout = WDT_MAX_TIMEOUT;
+	wdd->max_hw_heartbeat_ms = WDT_MAX_TIMEOUT;
+	wdd->parent = &pdev->dev;
+
+	watchdog_set_drvdata(wdd, wdt);
+	watchdog_set_nowayout(wdd, true);
+
+	ret = watchdog_init_timeout(wdd, WDT_DEFAULT_TIMEOUT, &pdev->dev);
+	if (ret)
+		dev_warn(&pdev->dev,
+			 "unable to set timeout value, using default\n");
+
+	ret = watchdog_register_device(wdd);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"failed to register watchdog device\n");
+		goto err;
+	}
+
+	platform_set_drvdata(pdev, wdt);
+
+	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);
+
+	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

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#1614713

FromGuenter Roeck <linux@roeck-us.net>
Date2017-04-02 13:50 +0200
Message-ID<trMb7-8kH-11@gated-at.bofh.it>
In reply to#1613158
On 03/30/2017 08:15 AM, Yannick Fertre wrote:
> This patch adds IWDG (Independent WatchDoG) support for STM32 platform.
>
> Signed-off-by: Yannick FERTRE <yannick.fertre@st.com>
> ---
>  drivers/watchdog/Kconfig      |  12 ++
>  drivers/watchdog/Makefile     |   1 +
>  drivers/watchdog/stm32_iwdg.c | 260 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 273 insertions(+)
>  create mode 100644 drivers/watchdog/stm32_iwdg.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 52a70ee..d014deb 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -744,6 +744,18 @@ 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 support for the watchdog timer
> +	  in stm32 SoCs.
> +
> +	  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..629c305
> --- /dev/null
> +++ b/drivers/watchdog/stm32_iwdg.c
> @@ -0,0 +1,260 @@
> +/*
> + * 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>
> +
> +/* watchdog trigger timeout, in seconds */
> +#define WDT_MIN_TIMEOUT		1
> +#define WDT_MAX_TIMEOUT		32
> +#define WDT_DEFAULT_TIMEOUT	30
> +
> +/* 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;
> +	void __iomem		*regs;
> +	struct clk		*clk;
> +	unsigned int		rate;
> +};
> +
> +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(wdd->parent, "%s\n", __func__);
> +
> +	/* enable watchdog */
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
> +
> +	/* prescaler fixed to 256 */
> +	reload = (wdd->timeout * wdt->rate) / 256;
> +	if (reload > RLR_MAX + 1)
> +		reload = RLR_MAX + 1;
> +
> +	/* set prescaler & reload registers */
> +	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(wdd->parent,
> +			"Fail to set prescaler or reload registers\n");
> +		return ret;
> +	}
> +
> +	/* reload watchdog */
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
> +
> +	return 0;
> +}
> +
> +static int stm32_iwdg_ping(struct watchdog_device *wdd)
> +{
> +	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
> +
> +	dev_dbg(wdd->parent, "%s\n", __func__);
> +
> +	/* reload watchdog */
> +	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
> +
> +	return 0;
> +}
> +
> +static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
> +				  unsigned int timeout)
> +{
> +	dev_dbg(wdd->parent, "%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,
> +	.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 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->clk = clk;
> +	wdt->rate = clk_get_rate(clk);
> +
> +	/* Initialize struct watchdog_device. */
> +	wdd = &wdt->wdd;
> +	wdd->info = &stm32_iwdg_info;
> +	wdd->ops = &stm32_iwdg_ops;
> +	wdd->min_timeout = WDT_MIN_TIMEOUT;
> +	wdd->max_timeout = WDT_MAX_TIMEOUT;
> +	wdd->max_hw_heartbeat_ms = WDT_MAX_TIMEOUT;

This would have to be in milli-seconds. Also only provide max_timeout
or max_hw_heartbeat_ms, but not both.

> +	wdd->parent = &pdev->dev;
> +
> +	watchdog_set_drvdata(wdd, wdt);
> +	watchdog_set_nowayout(wdd, true);
> +
> +	ret = watchdog_init_timeout(wdd, WDT_DEFAULT_TIMEOUT, &pdev->dev);

Timeout parameter should be 0 to give the core a chance to pick up a timeout
from fdt if specified. Otherwise the call is quite useless.

> +	if (ret)
> +		dev_warn(&pdev->dev,
> +			 "unable to set timeout value, using default\n");
> +
> +	ret = watchdog_register_device(wdd);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"failed to register watchdog device\n");
> +		goto err;
> +	}
> +
> +	platform_set_drvdata(pdev, wdt);
> +
> +	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);
> +
> +	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");
>

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#1617930

FromYannick FERTRE <yannick.fertre@st.com>
Date2017-04-06 14:30 +0200
Message-ID<tteI2-8tl-23@gated-at.bofh.it>
In reply to#1614713
Hi Guenter,
thanks for your help.

Best regards

On 04/02/2017 01:48 PM, Guenter Roeck wrote:
> On 03/30/2017 08:15 AM, Yannick Fertre wrote:
>> This patch adds IWDG (Independent WatchDoG) support for STM32 platform.
>>
>> Signed-off-by: Yannick FERTRE <yannick.fertre@st.com>
>> ---
>>  drivers/watchdog/Kconfig      |  12 ++
>>  drivers/watchdog/Makefile     |   1 +
>>  drivers/watchdog/stm32_iwdg.c | 260
>> ++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 273 insertions(+)
>>  create mode 100644 drivers/watchdog/stm32_iwdg.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 52a70ee..d014deb 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -744,6 +744,18 @@ 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 support for the watchdog timer
>> +      in stm32 SoCs.
>> +
>> +      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..629c305
>> --- /dev/null
>> +++ b/drivers/watchdog/stm32_iwdg.c
>> @@ -0,0 +1,260 @@
>> +/*
>> + * 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>
>> +
>> +/* watchdog trigger timeout, in seconds */
>> +#define WDT_MIN_TIMEOUT        1
>> +#define WDT_MAX_TIMEOUT        32
>> +#define WDT_DEFAULT_TIMEOUT    30
>> +
>> +/* 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;
>> +    void __iomem        *regs;
>> +    struct clk        *clk;
>> +    unsigned int        rate;
>> +};
>> +
>> +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(wdd->parent, "%s\n", __func__);
>> +
>> +    /* enable watchdog */
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
>> +
>> +    /* prescaler fixed to 256 */
>> +    reload = (wdd->timeout * wdt->rate) / 256;
>> +    if (reload > RLR_MAX + 1)
>> +        reload = RLR_MAX + 1;
>> +
>> +    /* set prescaler & reload registers */
>> +    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(wdd->parent,
>> +            "Fail to set prescaler or reload registers\n");
>> +        return ret;
>> +    }
>> +
>> +    /* reload watchdog */
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
>> +
>> +    return 0;
>> +}
>> +
>> +static int stm32_iwdg_ping(struct watchdog_device *wdd)
>> +{
>> +    struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
>> +
>> +    dev_dbg(wdd->parent, "%s\n", __func__);
>> +
>> +    /* reload watchdog */
>> +    reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
>> +
>> +    return 0;
>> +}
>> +
>> +static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
>> +                  unsigned int timeout)
>> +{
>> +    dev_dbg(wdd->parent, "%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,
>> +    .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 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->clk = clk;
>> +    wdt->rate = clk_get_rate(clk);
>> +
>> +    /* Initialize struct watchdog_device. */
>> +    wdd = &wdt->wdd;
>> +    wdd->info = &stm32_iwdg_info;
>> +    wdd->ops = &stm32_iwdg_ops;
>> +    wdd->min_timeout = WDT_MIN_TIMEOUT;
>> +    wdd->max_timeout = WDT_MAX_TIMEOUT;
>> +    wdd->max_hw_heartbeat_ms = WDT_MAX_TIMEOUT;
>
> This would have to be in milli-seconds. Also only provide max_timeout
> or max_hw_heartbeat_ms, but not both.
>
Fix in V5
>> +    wdd->parent = &pdev->dev;
>> +
>> +    watchdog_set_drvdata(wdd, wdt);
>> +    watchdog_set_nowayout(wdd, true);
>> +
>> +    ret = watchdog_init_timeout(wdd, WDT_DEFAULT_TIMEOUT, &pdev->dev);
>
> Timeout parameter should be 0 to give the core a chance to pick up a
> timeout
> from fdt if specified. Otherwise the call is quite useless.
Fix in V5
>
>> +    if (ret)
>> +        dev_warn(&pdev->dev,
>> +             "unable to set timeout value, using default\n");
>> +
>> +    ret = watchdog_register_device(wdd);
>> +    if (ret) {
>> +        dev_err(&pdev->dev,
>> +            "failed to register watchdog device\n");
>> +        goto err;
>> +    }
>> +
>> +    platform_set_drvdata(pdev, wdt);
>> +
>> +    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);
>> +
>> +    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");
>>
>

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