diff options
Diffstat (limited to 'drivers/power/reset/gpio-restart.c')
| -rw-r--r-- | drivers/power/reset/gpio-restart.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/drivers/power/reset/gpio-restart.c b/drivers/power/reset/gpio-restart.c new file mode 100644 index 000000000..829b45f42 --- /dev/null +++ b/drivers/power/reset/gpio-restart.c @@ -0,0 +1,148 @@ +/* + * 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 = 129; + 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", + .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"); |