[RFC] watchdog: GPIO-controlled watchdog

* [RFC] watchdog: GPIO-controlled watchdog
@ 2013-07-14 15:09 Alexander Shiyan
  2013-07-14 19:43 ` Guenter Roeck
  0 siblings, 1 reply; 6+ messages in thread
From: Alexander Shiyan @ 2013-07-14 15:09 UTC (permalink / raw)
  To: linux-watchdog; +Cc: Wim Van Sebroeck, Alexander Shiyan

This patch adds a watchdog driver for devices controlled through GPIO,
(Analog Devices ADM706, for example). Driver written for DT-based systems
only. No description for Documentation/devicetree yet.
Comments are welcome.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
---
 drivers/watchdog/Kconfig    |   8 +++
 drivers/watchdog/Makefile   |   1 +
 drivers/watchdog/gpio_wdt.c | 121 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 130 insertions(+)
 create mode 100644 drivers/watchdog/gpio_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 3eb1cc6..811030c 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -87,6 +87,14 @@ config DA9055_WATCHDOG
 	  This driver can also be built as a module.  If so, the module
 	  will be called da9055_wdt.
 
+config GPIO_WATCHDOG
+	tristate "Watchdog device controlled through GPIO-line"
+	depends on OF_GPIO
+	select WATCHDOG_CORE
+	help
+	  If you say yes here you get support for watchdog device
+	  controlled through GPIO-line.
+
 config WM831X_WATCHDOG
 	tristate "WM831x watchdog"
 	depends on MFD_WM831X
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index ec26899..ca85cbd 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -168,6 +168,7 @@ obj-$(CONFIG_XEN_WDT) += xen_wdt.o
 # Architecture Independent
 obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
 obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
+obj-$(CONFIG_GPIO_WATCHDOG)	+= gpio_wdt.o
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
 obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
new file mode 100644
index 0000000..ee4ffba
--- /dev/null
+++ b/drivers/watchdog/gpio_wdt.c
@@ -0,0 +1,121 @@
+/*
+ * Driver for watchdog device controlled through GPIO-line
+ *
+ * Author: 2013, Alexander Shiyan <shc_work@mail.ru>
+ *
+ * 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/err.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+struct gpio_wdt_priv {
+	int			gpio;
+	struct watchdog_device	wdd;
+};
+
+static int gpio_wdt_ping(struct watchdog_device *wdd)
+{
+	struct gpio_wdt_priv *priv =
+		container_of(wdd, struct gpio_wdt_priv, wdd);
+
+	/* Toggle output */
+	gpio_set_value(priv->gpio, !gpio_get_value(priv->gpio));
+
+	return 0;
+}
+
+static int gpio_wdt_start(struct watchdog_device *wdd)
+{
+	struct gpio_wdt_priv *priv =
+		container_of(wdd, struct gpio_wdt_priv, wdd);
+
+	/* Enable watchdog by set output to logic level */
+	gpio_direction_output(priv->gpio, 0);
+	gpio_set_value(priv->gpio, 1);
+
+	return 0;
+}
+
+static int gpio_wdt_stop(struct watchdog_device *wdd)
+{
+	struct gpio_wdt_priv *priv =
+		container_of(wdd, struct gpio_wdt_priv, wdd);
+
+	/* Disable watchdog by set output to tristate */
+	return gpio_direction_input(priv->gpio);
+}
+
+static const struct watchdog_info gpio_wdt_ident = {
+	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+	.identity	= "GPIO Watchdog",
+};
+
+static const struct watchdog_ops gpio_wdt_ops = {
+	.owner	= THIS_MODULE,
+	.ping	= gpio_wdt_ping,
+	.start	= gpio_wdt_start,
+	.stop	= gpio_wdt_stop,
+};
+
+static int gpio_wdt_probe(struct platform_device *pdev)
+{
+	struct gpio_wdt_priv *priv;
+	bool nowayout;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->gpio = of_get_gpio(pdev->dev.of_node, 0);
+	if (priv->gpio < 0)
+		return priv->gpio;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->wdd.info = &gpio_wdt_ident;
+	priv->wdd.ops = &gpio_wdt_ops;
+
+	nowayout = of_property_read_bool(pdev->dev.of_node, "wdt,nowayout");
+	if (!nowayout)
+		nowayout = WATCHDOG_NOWAYOUT;
+	watchdog_set_nowayout(&priv->wdd, nowayout);
+
+	return watchdog_register_device(&priv->wdd);
+}
+
+static int gpio_wdt_remove(struct platform_device *pdev)
+{
+	struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&priv->wdd);
+
+	return 0;
+}
+
+static const struct of_device_id gpio_wdt_dt_ids[] = {
+	{ .compatible = "linux,wdt-gpio", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
+
+static struct platform_driver gpio_wdt_driver = {
+	.driver	= {
+		.name		= "gpio-wdt",
+		.owner		= THIS_MODULE,
+		.of_match_table	= of_match_ptr(gpio_wdt_dt_ids),
+	},
+	.probe	= gpio_wdt_probe,
+	.remove	= gpio_wdt_remove,
+};
+module_platform_driver(gpio_wdt_driver);
+
+MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
+MODULE_DESCRIPTION("GPIO Watchdog");
+MODULE_LICENSE("GPL");
-- 
1.8.1.5


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