On 11/26/2013 08:26 AM, Alexander Shiyan wrote:
This patch adds a watchdog driver for devices controlled through GPIO,
(Analog Devices ADM706, IC 555 etc).
Signed-off-by: Alexander Shiyan <[email protected]>
---
A list of changes since v1 would be helpful.
.../devicetree/bindings/watchdog/gpio-wdt.txt | 23 ++
drivers/watchdog/Kconfig | 8 +
drivers/watchdog/Makefile | 1 +
drivers/watchdog/gpio_wdt.c | 246 +++++++++++++++++++++
4 files changed, 278 insertions(+)
create mode 100644 Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
create mode 100644 drivers/watchdog/gpio_wdt.c
diff --git a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
new file mode 100644
index 0000000..08ba8e5
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
@@ -0,0 +1,23 @@
+* GPIO-controlled Watchdog
+
+Required Properties:
+- compatible: Should contain "linux,wdt-gpio".
Should ?
+- gpios: From common gpio binding; gpio connection to WDT reset pin.
+- wdt-gpio,hw_algo: The algorithm used by the driver. Should be one
+ of the following values:
Should ?
+ - toggle: Either a high-to-low or a low-to-high transition clears
+ the WDT counter. The watchdog timer is disabled when GPIO is
+ left floating or connected to a three-state buffer.
+ - level: Low or high level starts counting WDT timeout,
+ the opposite level disables the WDT. Active level is determined
+ by the GPIO flags.
+- wdt-gpio,hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds).
+
+Example:
+ watchdog: watchdog {
+ /* ADM706 */
+ compatible = "linux,wdt-gpio";
Oddly enough, the bindings could be used by non-Linux operating systems,
but who am I to argue. Fine if this is what the DT maintainers want to see.
+ gpios = <&gpio3 9 GPIO_ACTIVE_LOW>;
+ wdt-gpio,hw_algo = "toggle";
+ wdt-gpio,hw_margin_ms = <1600>;
Is this a new means to name device specific properties ?
"wdt-gpio" in those bindings is quite redundant with "wdt-gpio"
in the compatible property. Again, though, who am I to argue.
+ };
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 5be6e91..968a882 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 91bd95a..dc17275 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -171,6 +171,7 @@ 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..c7166be
--- /dev/null
+++ b/drivers/watchdog/gpio_wdt.c
@@ -0,0 +1,246 @@
+/*
+ * Driver for watchdog device controlled through GPIO-line
+ *
+ * Author: 2013, Alexander Shiyan <[email protected]>
+ *
+ * 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/delay.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+
+#define SOFT_TIMEOUT_MIN 1
+#define SOFT_TIMEOUT_DEF 60
+#define SOFT_TIMEOUT_MAX 0xffff
+
+enum {
+ HW_ALGO_TOGGLE,
+ HW_ALGO_LEVEL,
+};
+
+struct gpio_wdt_priv {
+ int gpio;
+ bool active_low;
+ bool state;
+ unsigned int hw_algo;
+ unsigned int hw_margin;
+ unsigned long last_jiffies;
+ struct notifier_block notifier;
+ struct timer_list timer;
+ struct watchdog_device wdd;
+};
+
+static int gpio_wdt_disable(struct gpio_wdt_priv *priv)
+{
+ gpio_set_value_cansleep(priv->gpio, !priv->active_low);
+
+ /* Put GPIO back to tristate */
+ if (priv->hw_algo == HW_ALGO_TOGGLE)
+ return gpio_direction_input(priv->gpio);
+
No disable for 'level' watchdogs ? Shouldn't it be set to the opposite
of priv->state ?
+ return 0;
Since this is an internal function which never returns anything but 0,
you might as well make it void.
+}
+
+static int gpio_wdt_start(struct watchdog_device *wdd)
+{
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ priv->state = priv->active_low;
+ gpio_direction_output(priv->gpio, priv->state);
+ priv->last_jiffies = jiffies;
+ mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);
+
+ return 0;
+}
+
+static int gpio_wdt_stop(struct watchdog_device *wdd)
+{
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ mod_timer(&priv->timer, 0);
+
+ return gpio_wdt_disable(priv);
+}
+
+static int gpio_wdt_ping(struct watchdog_device *wdd)
+{
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ priv->last_jiffies = jiffies;
+
+ return 0;
+}
+
+static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
+{
+ wdd->timeout = t;
+
+ return 0;
+}
+
+static void gpio_wdt_hwping(unsigned long data)
+{
+ struct watchdog_device *wdd = (struct watchdog_device *)data;
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ if (time_before(jiffies, priv->last_jiffies +
+ msecs_to_jiffies(wdd->timeout * 1000))) {
+ /* Restart timer */
+ mod_timer(&priv->timer, jiffies + priv->hw_margin);
+
+ switch (priv->hw_algo) {
+ case HW_ALGO_TOGGLE:
+ /* Toggle output pin */
+ priv->state = !priv->state;
+ gpio_set_value_cansleep(priv->gpio, priv->state);
+ break;
+ case HW_ALGO_LEVEL:
+ /* Pulse */
+ gpio_set_value_cansleep(priv->gpio, !priv->active_low);
+ udelay(1);
Pretty arbitrary toggle time. Should this be a property ?
+ gpio_set_value_cansleep(priv->gpio, priv->active_low);
+ break;
+ }
+ } else
+ dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
Coding style (chapter 3): else should be in { } too.
+}
+
+static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
+ void *unused)
+{
+ struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
+ notifier);
+
+ mod_timer(&priv->timer, 0);
+
+ switch (code) {
+ case SYS_HALT:
+ case SYS_POWER_OFF:
+ gpio_wdt_disable(priv);
+ break;
+ case SYS_DOWN:
This case statement is unnecessary.
+ default:
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static const struct watchdog_info gpio_wdt_ident = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
+ WDIOF_SETTIMEOUT,
+ .identity = "GPIO Watchdog",
+};
+
+static const struct watchdog_ops gpio_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = gpio_wdt_start,
+ .stop = gpio_wdt_stop,
+ .ping = gpio_wdt_ping,
+ .set_timeout = gpio_wdt_set_timeout,
+};
+
+static int gpio_wdt_probe(struct platform_device *pdev)
+{
+ struct gpio_wdt_priv *priv;
+ enum of_gpio_flags flags;
+ const __be32 *prp;
+ u32 hw_margin;
+ int ret;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
+ if (!gpio_is_valid(priv->gpio))
+ return priv->gpio;
+
+ priv->active_low = !!(flags & OF_GPIO_ACTIVE_LOW);
+
!! is unnecessary for assignments to booleans.
+ ret = devm_gpio_request_one(&pdev->dev, priv->gpio, GPIOF_IN,
+ dev_name(&pdev->dev));
+ if (ret)
+ return ret;
+
+ prp = of_get_property(pdev->dev.of_node, "wdt-gpio,hw_algo", NULL);
+ if (!prp)
+ return -EINVAL;
I am a bit concerned about using of_get_property() to read a string.
If the provided property is an integer, one can only hope that nothing odd
happens.
How about using of_property_read_string() instead ? That would at least
provide some protection.
+ if (!strncmp((const char *)prp, "toggle", 6))
+ priv->hw_algo = HW_ALGO_TOGGLE;
+ else if (!strncmp((const char *)prp, "level", 5))
+ priv->hw_algo = HW_ALGO_LEVEL;
+ else
+ return -ENOTSUPP;
This suggests that the value is valid but not supported. -EINVAL may be better.
+
+ prp = of_get_property(pdev->dev.of_node, "wdt-gpio,hw_margin_ms", NULL);
+ if (!prp)
+ return -EINVAL;
There is also of_property_read_u32().
+ hw_margin = be32_to_cpu(*prp);
+ /* Disallow values lower than 2 and higher than 65535 ms */
+ if ((hw_margin < 2) || (hw_margin > 65535))
+ return -EINVAL;
+
+ /* Use safe value (2/3 of real timeout) */
+ priv->hw_margin = msecs_to_jiffies(hw_margin * 2 / 3);
+
Hope this is safe enough. I would have used 1/2, but that
is really up to you to decide.
+ watchdog_set_drvdata(&priv->wdd, priv);
+
+ priv->wdd.info = &gpio_wdt_ident;
+ priv->wdd.ops = &gpio_wdt_ops;
+ priv->wdd.min_timeout = SOFT_TIMEOUT_MIN;
+ priv->wdd.max_timeout = SOFT_TIMEOUT_MAX;
+
+ if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
+ priv->wdd.timeout = SOFT_TIMEOUT_DEF;
+
+ setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
+
+ priv->notifier.notifier_call = gpio_wdt_notify_sys;
+ ret = register_reboot_notifier(&priv->notifier);
+ if (ret)
+ return ret;
+
+ return watchdog_register_device(&priv->wdd);
If this fails you don't call unregister_reboot_notifier.
+}
+
+static int gpio_wdt_remove(struct platform_device *pdev)
+{
+ struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
+
+ del_timer_sync(&priv->timer);
+ unregister_reboot_notifier(&priv->notifier);
+ 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 = gpio_wdt_dt_ids,
+ },
+ .probe = gpio_wdt_probe,
+ .remove = gpio_wdt_remove,
+};
+module_platform_driver(gpio_wdt_driver);
+
+MODULE_AUTHOR("Alexander Shiyan <[email protected]>");
+MODULE_DESCRIPTION("GPIO Watchdog");
+MODULE_LICENSE("GPL");
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