* [PATCH v2 1/1] power: Add simple gpio-restart driver
2014-08-27 19:23 [PATCH v2 0/1] gpio-restart restart handler David Riley
@ 2014-08-27 19:23 ` David Riley
2014-09-19 4:35 ` Guenter Roeck
2014-09-26 20:23 ` Sebastian Reichel
0 siblings, 2 replies; 4+ messages in thread
From: David Riley @ 2014-08-27 19:23 UTC (permalink / raw)
To: Sebastian Reichel, Dmitry Eremin-Solenikov, David Woodhouse
Cc: Guenter Roeck, Rob Herring, Pawel Moll, Mark Rutland,
Ian Campbell, Kumar Gala, Grant Likely, David Riley,
Arnd Bergmann, Anton Vorontsov, Marc Carino, Anders Berg,
Laxman Dewangan, Ivan Khoronzhuk, Maxime Ripard, Haojian Zhuang,
Jamie Lentin, Doug Anderson, devicetree, linux-kernel, linux-pm
This driver registers a restart handler to set a GPIO line high/low
to reset a board based on devicetree bindings.
Signed-off-by: David Riley <davidriley@chromium.org>
---
.../devicetree/bindings/gpio/gpio-restart.txt | 54 ++++++++
drivers/power/reset/Kconfig | 8 ++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/gpio-restart.c | 149 +++++++++++++++++++++
4 files changed, 212 insertions(+)
create mode 100644 Documentation/devicetree/bindings/gpio/gpio-restart.txt
create mode 100644 drivers/power/reset/gpio-restart.c
diff --git a/Documentation/devicetree/bindings/gpio/gpio-restart.txt b/Documentation/devicetree/bindings/gpio/gpio-restart.txt
new file mode 100644
index 0000000..af3701b
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-restart.txt
@@ -0,0 +1,54 @@
+Drive a GPIO line that can be used to restart the system from a restart
+handler.
+
+This binding supports level and edge triggered reset. At driver load
+time, the driver will request the given gpio line and install a restart
+handler. If the optional properties 'open-source' is not found, the GPIO line
+will be driven in the inactive state. Otherwise its not driven until
+the restart is initiated.
+
+When the system is restarted, the restart handler will be invoked in
+priority order. The gpio is configured as an output, and driven active,
+triggering a level triggered reset condition. This will also cause an
+inactive->active edge condition, triggering positive edge triggered
+reset. After a delay specified by active-delay, the GPIO is set to
+inactive, thus causing an active->inactive edge, triggering negative edge
+triggered reset. After a delay specified by inactive-delay, the GPIO
+is driven active again. After a delay specified by wait-delay, the
+restart handler completes allowing other restart handlers to be attempted.
+
+Required properties:
+- compatible : should be "gpio-restart".
+- gpios : The GPIO to set high/low, see "gpios property" in
+ Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be
+ low to reset the board set it to "Active Low", otherwise set
+ gpio to "Active High".
+
+Optional properties:
+- open-source : Treat the GPIO as being open source and defer driving
+ it to when the restart is initiated. If this optional property is not
+ specified, the GPIO is initialized as an output in its inactive state.
+- priority : A priority ranging from 0 to 255 (default 128) according to
+ the following guidelines:
+ 0: Restart handler of last resort, with limited restart
+ capabilities
+ 128: Default restart handler; use if no other restart handler is
+ expected to be available, and/or if restart functionality is
+ sufficient to restart the entire system
+ 255: Highest priority restart handler, will preempt all other
+ restart handlers
+- active-delay: Delay (default 100) to wait after driving gpio active [ms]
+- inactive-delay: Delay (default 100) to wait after driving gpio inactive [ms]
+- wait-delay: Delay (default 3000) to wait after completing restart
+ sequence [ms]
+
+Examples:
+
+gpio-restart {
+ compatible = "gpio-restart";
+ gpios = <&gpio 4 0>;
+ priority = <128>;
+ active-delay = <100>;
+ inactive-delay = <100>;
+ wait-delay = <3000>;
+};
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index ca41523..f07e26c 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -39,6 +39,14 @@ config POWER_RESET_GPIO
If your board needs a GPIO high/low to power down, say Y and
create a binding in your devicetree.
+config POWER_RESET_GPIO_RESTART
+ bool "GPIO restart driver"
+ depends on OF_GPIO && POWER_RESET
+ help
+ This driver supports restarting your board via a GPIO line.
+ If your board needs a GPIO high/low to restart, say Y and
+ create a binding in your devicetree.
+
config POWER_RESET_HISI
bool "Hisilicon power-off driver"
depends on POWER_RESET && ARCH_HISI
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index a42e70e..199cb6e 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_POWER_RESET_AS3722) += as3722-poweroff.o
obj-$(CONFIG_POWER_RESET_AXXIA) += axxia-reset.o
obj-$(CONFIG_POWER_RESET_BRCMSTB) += brcmstb-reboot.o
obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
+obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
diff --git a/drivers/power/reset/gpio-restart.c b/drivers/power/reset/gpio-restart.c
new file mode 100644
index 0000000..a76829b
--- /dev/null
+++ b/drivers/power/reset/gpio-restart.c
@@ -0,0 +1,149 @@
+/*
+ * Toggles a GPIO pin to restart a device
+ *
+ * Copyright (C) 2014 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Based on the gpio-poweroff driver.
+ */
+#include <linux/reboot.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of_platform.h>
+#include <linux/module.h>
+
+struct gpio_restart {
+ struct gpio_desc *reset_gpio;
+ struct notifier_block restart_handler;
+ u32 active_delay_ms;
+ u32 inactive_delay_ms;
+ u32 wait_delay_ms;
+};
+
+static int gpio_restart_notify(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ struct gpio_restart *gpio_restart =
+ container_of(this, struct gpio_restart, restart_handler);
+
+ /* drive it active, also inactive->active edge */
+ gpiod_direction_output(gpio_restart->reset_gpio, 1);
+ mdelay(gpio_restart->active_delay_ms);
+
+ /* drive inactive, also active->inactive edge */
+ gpiod_set_value(gpio_restart->reset_gpio, 0);
+ mdelay(gpio_restart->inactive_delay_ms);
+
+ /* drive it active, also inactive->active edge */
+ gpiod_set_value(gpio_restart->reset_gpio, 1);
+
+ /* give it some time */
+ mdelay(gpio_restart->wait_delay_ms);
+
+ WARN_ON(1);
+
+ return NOTIFY_DONE;
+}
+
+static int gpio_restart_probe(struct platform_device *pdev)
+{
+ struct gpio_restart *gpio_restart;
+ bool open_source = false;
+ u32 property;
+ int ret;
+
+ gpio_restart = devm_kzalloc(&pdev->dev, sizeof(*gpio_restart),
+ GFP_KERNEL);
+ if (!gpio_restart)
+ return -ENOMEM;
+
+ open_source = of_property_read_bool(pdev->dev.of_node, "open-source");
+
+ gpio_restart->reset_gpio = devm_gpiod_get(&pdev->dev, NULL,
+ open_source ? GPIOD_IN : GPIOD_OUT_LOW);
+ if (IS_ERR(gpio_restart->reset_gpio)) {
+ dev_err(&pdev->dev, "Could net get reset GPIO\n");
+ return PTR_ERR(gpio_restart->reset_gpio);
+ }
+
+ gpio_restart->restart_handler.notifier_call = gpio_restart_notify;
+ gpio_restart->restart_handler.priority = 128;
+ gpio_restart->active_delay_ms = 100;
+ gpio_restart->inactive_delay_ms = 100;
+ gpio_restart->wait_delay_ms = 3000;
+
+ ret = of_property_read_u32(pdev->dev.of_node, "priority", &property);
+ if (!ret) {
+ if (property > 255)
+ dev_err(&pdev->dev, "Invalid priority property: %u\n",
+ property);
+ else
+ gpio_restart->restart_handler.priority = property;
+ }
+
+ of_property_read_u32(pdev->dev.of_node, "active-delay",
+ &gpio_restart->active_delay_ms);
+ of_property_read_u32(pdev->dev.of_node, "inactive-delay",
+ &gpio_restart->inactive_delay_ms);
+ of_property_read_u32(pdev->dev.of_node, "wait-delay",
+ &gpio_restart->wait_delay_ms);
+
+ platform_set_drvdata(pdev, gpio_restart);
+
+ ret = register_restart_handler(&gpio_restart->restart_handler);
+ if (ret) {
+ dev_err(&pdev->dev, "%s: cannot register restart handler, %d\n",
+ __func__, ret);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int gpio_restart_remove(struct platform_device *pdev)
+{
+ struct gpio_restart *gpio_restart = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = unregister_restart_handler(&gpio_restart->restart_handler);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "%s: cannot unregister restart handler, %d\n",
+ __func__, ret);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static const struct of_device_id of_gpio_restart_match[] = {
+ { .compatible = "gpio-restart", },
+ {},
+};
+
+static struct platform_driver gpio_restart_driver = {
+ .probe = gpio_restart_probe,
+ .remove = gpio_restart_remove,
+ .driver = {
+ .name = "restart-gpio",
+ .owner = THIS_MODULE,
+ .of_match_table = of_gpio_restart_match,
+ },
+};
+
+module_platform_driver(gpio_restart_driver);
+
+MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
+MODULE_DESCRIPTION("GPIO restart driver");
+MODULE_LICENSE("GPL");
--
2.0.0
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