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power: Add simple gpio-restart driver
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> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Sebastian Reichel <sre@kernel.org>
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54
Documentation/devicetree/bindings/gpio/gpio-restart.txt
Normal file
54
Documentation/devicetree/bindings/gpio/gpio-restart.txt
Normal file
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Drive a GPIO line that can be used to restart the system from a restart
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handler.
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This binding supports level and edge triggered reset. At driver load
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time, the driver will request the given gpio line and install a restart
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handler. If the optional properties 'open-source' is not found, the GPIO line
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will be driven in the inactive state. Otherwise its not driven until
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the restart is initiated.
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When the system is restarted, the restart handler will be invoked in
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priority order. The gpio is configured as an output, and driven active,
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triggering a level triggered reset condition. This will also cause an
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inactive->active edge condition, triggering positive edge triggered
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reset. After a delay specified by active-delay, the GPIO is set to
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inactive, thus causing an active->inactive edge, triggering negative edge
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triggered reset. After a delay specified by inactive-delay, the GPIO
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is driven active again. After a delay specified by wait-delay, the
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restart handler completes allowing other restart handlers to be attempted.
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Required properties:
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- compatible : should be "gpio-restart".
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- gpios : The GPIO to set high/low, see "gpios property" in
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Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be
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low to reset the board set it to "Active Low", otherwise set
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gpio to "Active High".
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Optional properties:
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- open-source : Treat the GPIO as being open source and defer driving
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it to when the restart is initiated. If this optional property is not
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specified, the GPIO is initialized as an output in its inactive state.
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- priority : A priority ranging from 0 to 255 (default 128) according to
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the following guidelines:
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0: Restart handler of last resort, with limited restart
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capabilities
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128: Default restart handler; use if no other restart handler is
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expected to be available, and/or if restart functionality is
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sufficient to restart the entire system
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255: Highest priority restart handler, will preempt all other
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restart handlers
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- active-delay: Delay (default 100) to wait after driving gpio active [ms]
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- inactive-delay: Delay (default 100) to wait after driving gpio inactive [ms]
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- wait-delay: Delay (default 3000) to wait after completing restart
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sequence [ms]
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Examples:
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gpio-restart {
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compatible = "gpio-restart";
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gpios = <&gpio 4 0>;
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priority = <128>;
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active-delay = <100>;
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inactive-delay = <100>;
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wait-delay = <3000>;
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};
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@ -39,6 +39,14 @@ config POWER_RESET_GPIO
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If your board needs a GPIO high/low to power down, say Y and
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create a binding in your devicetree.
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config POWER_RESET_GPIO_RESTART
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bool "GPIO restart driver"
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depends on OF_GPIO && POWER_RESET
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help
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This driver supports restarting your board via a GPIO line.
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If your board needs a GPIO high/low to restart, say Y and
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create a binding in your devicetree.
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config POWER_RESET_HISI
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bool "Hisilicon power-off driver"
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depends on POWER_RESET && ARCH_HISI
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@ -2,6 +2,7 @@ obj-$(CONFIG_POWER_RESET_AS3722) += as3722-poweroff.o
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obj-$(CONFIG_POWER_RESET_AXXIA) += axxia-reset.o
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obj-$(CONFIG_POWER_RESET_BRCMSTB) += brcmstb-reboot.o
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obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
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obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
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obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
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obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
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obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
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149
drivers/power/reset/gpio-restart.c
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149
drivers/power/reset/gpio-restart.c
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/*
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* Toggles a GPIO pin to restart a device
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*
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* Copyright (C) 2014 Google, Inc.
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* Based on the gpio-poweroff driver.
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*/
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#include <linux/reboot.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/platform_device.h>
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#include <linux/gpio/consumer.h>
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#include <linux/of_platform.h>
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#include <linux/module.h>
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struct gpio_restart {
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struct gpio_desc *reset_gpio;
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struct notifier_block restart_handler;
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u32 active_delay_ms;
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u32 inactive_delay_ms;
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u32 wait_delay_ms;
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};
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static int gpio_restart_notify(struct notifier_block *this,
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unsigned long mode, void *cmd)
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{
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struct gpio_restart *gpio_restart =
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container_of(this, struct gpio_restart, restart_handler);
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/* drive it active, also inactive->active edge */
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gpiod_direction_output(gpio_restart->reset_gpio, 1);
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mdelay(gpio_restart->active_delay_ms);
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/* drive inactive, also active->inactive edge */
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gpiod_set_value(gpio_restart->reset_gpio, 0);
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mdelay(gpio_restart->inactive_delay_ms);
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/* drive it active, also inactive->active edge */
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gpiod_set_value(gpio_restart->reset_gpio, 1);
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/* give it some time */
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mdelay(gpio_restart->wait_delay_ms);
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WARN_ON(1);
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return NOTIFY_DONE;
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}
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static int gpio_restart_probe(struct platform_device *pdev)
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{
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struct gpio_restart *gpio_restart;
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bool open_source = false;
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u32 property;
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int ret;
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gpio_restart = devm_kzalloc(&pdev->dev, sizeof(*gpio_restart),
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GFP_KERNEL);
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if (!gpio_restart)
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return -ENOMEM;
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open_source = of_property_read_bool(pdev->dev.of_node, "open-source");
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gpio_restart->reset_gpio = devm_gpiod_get(&pdev->dev, NULL,
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open_source ? GPIOD_IN : GPIOD_OUT_LOW);
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if (IS_ERR(gpio_restart->reset_gpio)) {
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dev_err(&pdev->dev, "Could net get reset GPIO\n");
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return PTR_ERR(gpio_restart->reset_gpio);
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}
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gpio_restart->restart_handler.notifier_call = gpio_restart_notify;
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gpio_restart->restart_handler.priority = 128;
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gpio_restart->active_delay_ms = 100;
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gpio_restart->inactive_delay_ms = 100;
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gpio_restart->wait_delay_ms = 3000;
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ret = of_property_read_u32(pdev->dev.of_node, "priority", &property);
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if (!ret) {
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if (property > 255)
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dev_err(&pdev->dev, "Invalid priority property: %u\n",
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property);
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else
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gpio_restart->restart_handler.priority = property;
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}
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of_property_read_u32(pdev->dev.of_node, "active-delay",
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&gpio_restart->active_delay_ms);
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of_property_read_u32(pdev->dev.of_node, "inactive-delay",
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&gpio_restart->inactive_delay_ms);
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of_property_read_u32(pdev->dev.of_node, "wait-delay",
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&gpio_restart->wait_delay_ms);
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platform_set_drvdata(pdev, gpio_restart);
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ret = register_restart_handler(&gpio_restart->restart_handler);
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if (ret) {
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dev_err(&pdev->dev, "%s: cannot register restart handler, %d\n",
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__func__, ret);
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return -ENODEV;
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}
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return 0;
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}
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static int gpio_restart_remove(struct platform_device *pdev)
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{
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struct gpio_restart *gpio_restart = platform_get_drvdata(pdev);
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int ret;
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ret = unregister_restart_handler(&gpio_restart->restart_handler);
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if (ret) {
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dev_err(&pdev->dev,
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"%s: cannot unregister restart handler, %d\n",
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__func__, ret);
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return -ENODEV;
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}
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return 0;
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}
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static const struct of_device_id of_gpio_restart_match[] = {
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{ .compatible = "gpio-restart", },
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{},
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};
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static struct platform_driver gpio_restart_driver = {
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.probe = gpio_restart_probe,
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.remove = gpio_restart_remove,
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.driver = {
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.name = "restart-gpio",
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.owner = THIS_MODULE,
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.of_match_table = of_gpio_restart_match,
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},
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};
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module_platform_driver(gpio_restart_driver);
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MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
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MODULE_DESCRIPTION("GPIO restart driver");
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MODULE_LICENSE("GPL");
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