reset: Add driver for gpio-controlled reset pins
This driver implements a reset controller device that toggle a gpio connected to a reset pin of a peripheral IC. The delay between assertion and de-assertion of the reset signal can be configured via device tree. Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> Reviewed-by: Stephen Warren <swarren@nvidia.com> Reviewed-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Shawn Guo <shawn.guo@freescale.com>pull/10/head
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@ -0,0 +1,35 @@
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GPIO reset controller
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=====================
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A GPIO reset controller controls a single GPIO that is connected to the reset
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pin of a peripheral IC. Please also refer to reset.txt in this directory for
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common reset controller binding usage.
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Required properties:
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- compatible: Should be "gpio-reset"
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- reset-gpios: A gpio used as reset line. The gpio specifier for this property
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depends on the gpio controller that provides the gpio.
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- #reset-cells: 0, see below
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Optional properties:
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- reset-delay-us: delay in microseconds. The gpio reset line will be asserted for
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this duration to reset.
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- initially-in-reset: boolean. If not set, the initial state should be a
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deasserted reset line. If this property exists, the
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reset line should be kept in reset.
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example:
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sii902x_reset: gpio-reset {
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compatible = "gpio-reset";
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reset-gpios = <&gpio5 0 GPIO_ACTIVE_LOW>;
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reset-delay-us = <10000>;
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initially-in-reset;
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#reset-cells = <0>;
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};
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/* Device with nRESET pin connected to GPIO5_0 */
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sii902x@39 {
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/* ... */
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resets = <&sii902x_reset>; /* active-low GPIO5_0, 10 ms delay */
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};
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@ -54,6 +54,13 @@ config RESET_LANTIQ
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help
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This enables the reset controller driver for Lantiq / Intel XWAY SoCs.
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config RESET_GPIO
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tristate "GPIO reset controller support"
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depends on GPIOLIB && OF
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help
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This driver provides support for reset lines that are controlled
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directly by GPIOs.
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config RESET_LPC18XX
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bool "LPC18xx/43xx Reset Driver" if COMPILE_TEST
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default ARCH_LPC18XX
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@ -9,6 +9,7 @@ obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
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obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
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obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
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obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
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obj-$(CONFIG_RESET_GPIO) += gpio-reset.o
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obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
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obj-$(CONFIG_RESET_MESON) += reset-meson.o
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obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
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@ -0,0 +1,174 @@
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/*
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* GPIO Reset Controller driver
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*
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* Copyright 2013 Philipp Zabel, Pengutronix
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/gpio.h>
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#include <linux/module.h>
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#include <linux/of_gpio.h>
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#include <linux/platform_device.h>
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#include <linux/reset-controller.h>
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struct gpio_reset_data {
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struct reset_controller_dev rcdev;
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unsigned int gpio;
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bool active_low;
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s32 delay_us;
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};
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static void gpio_reset_set(struct reset_controller_dev *rcdev, int asserted)
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{
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struct gpio_reset_data *drvdata = container_of(rcdev,
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struct gpio_reset_data, rcdev);
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int value = asserted;
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if (drvdata->active_low)
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value = !value;
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gpio_set_value(drvdata->gpio, value);
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}
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static int gpio_reset(struct reset_controller_dev *rcdev, unsigned long id)
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{
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struct gpio_reset_data *drvdata = container_of(rcdev,
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struct gpio_reset_data, rcdev);
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if (drvdata->delay_us < 0)
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return -ENOSYS;
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gpio_reset_set(rcdev, 1);
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udelay(drvdata->delay_us);
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gpio_reset_set(rcdev, 0);
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return 0;
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}
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static int gpio_reset_assert(struct reset_controller_dev *rcdev,
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unsigned long id)
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{
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gpio_reset_set(rcdev, 1);
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return 0;
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}
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static int gpio_reset_deassert(struct reset_controller_dev *rcdev,
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unsigned long id)
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{
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gpio_reset_set(rcdev, 0);
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return 0;
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}
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static struct reset_control_ops gpio_reset_ops = {
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.reset = gpio_reset,
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.assert = gpio_reset_assert,
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.deassert = gpio_reset_deassert,
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};
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static int of_gpio_reset_xlate(struct reset_controller_dev *rcdev,
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const struct of_phandle_args *reset_spec)
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{
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if (WARN_ON(reset_spec->args_count != 0))
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return -EINVAL;
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return 0;
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}
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static int gpio_reset_probe(struct platform_device *pdev)
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{
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struct device_node *np = pdev->dev.of_node;
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struct gpio_reset_data *drvdata;
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enum of_gpio_flags flags;
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unsigned long gpio_flags;
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bool initially_in_reset;
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int ret;
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drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
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if (drvdata == NULL)
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return -ENOMEM;
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if (of_gpio_named_count(np, "reset-gpios") != 1) {
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dev_err(&pdev->dev,
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"reset-gpios property missing, or not a single gpio\n");
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return -EINVAL;
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}
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drvdata->gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags);
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if (drvdata->gpio == -EPROBE_DEFER) {
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return drvdata->gpio;
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} else if (!gpio_is_valid(drvdata->gpio)) {
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dev_err(&pdev->dev, "invalid reset gpio: %d\n", drvdata->gpio);
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return drvdata->gpio;
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}
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drvdata->active_low = flags & OF_GPIO_ACTIVE_LOW;
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ret = of_property_read_u32(np, "reset-delay-us", &drvdata->delay_us);
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if (ret < 0)
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drvdata->delay_us = -1;
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else if (drvdata->delay_us < 0)
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dev_warn(&pdev->dev, "reset delay too high\n");
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initially_in_reset = of_property_read_bool(np, "initially-in-reset");
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if (drvdata->active_low ^ initially_in_reset)
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gpio_flags = GPIOF_OUT_INIT_HIGH;
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else
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gpio_flags = GPIOF_OUT_INIT_LOW;
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ret = devm_gpio_request_one(&pdev->dev, drvdata->gpio, gpio_flags, NULL);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to request gpio %d: %d\n",
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drvdata->gpio, ret);
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return ret;
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}
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platform_set_drvdata(pdev, drvdata);
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drvdata->rcdev.of_node = np;
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drvdata->rcdev.owner = THIS_MODULE;
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drvdata->rcdev.nr_resets = 1;
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drvdata->rcdev.ops = &gpio_reset_ops;
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drvdata->rcdev.of_xlate = of_gpio_reset_xlate;
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reset_controller_register(&drvdata->rcdev);
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return 0;
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}
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static int gpio_reset_remove(struct platform_device *pdev)
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{
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struct gpio_reset_data *drvdata = platform_get_drvdata(pdev);
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reset_controller_unregister(&drvdata->rcdev);
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return 0;
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}
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static struct of_device_id gpio_reset_dt_ids[] = {
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{ .compatible = "gpio-reset" },
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{ }
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};
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static struct platform_driver gpio_reset_driver = {
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.probe = gpio_reset_probe,
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.remove = gpio_reset_remove,
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.driver = {
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.name = "gpio-reset",
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.owner = THIS_MODULE,
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.of_match_table = of_match_ptr(gpio_reset_dt_ids),
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},
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};
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module_platform_driver(gpio_reset_driver);
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MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
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MODULE_DESCRIPTION("gpio reset controller");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:gpio-reset");
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MODULE_DEVICE_TABLE(of, gpio_reset_dt_ids);
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