143 lines
3.6 KiB
C
143 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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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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* 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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ret = PTR_ERR_OR_ZERO(gpio_restart->reset_gpio);
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if (ret) {
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if (ret != -EPROBE_DEFER)
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dev_err(&pdev->dev, "Could not get reset GPIO\n");
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return ret;
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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 = 129;
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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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.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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