Commit cee544a4 authored by Krzysztof Kozlowski's avatar Krzysztof Kozlowski Committed by Philipp Zabel
Browse files

reset: gpio: Add GPIO-based reset controller 



Add a simple driver to control GPIO-based resets using the reset
controller API for the cases when the GPIOs are shared and reset should
be coordinated.  The driver is expected to be used by reset core
framework for ad-hoc reset controllers.

Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: default avatarKrzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240129115216.96479-4-krzysztof.kozlowski@linaro.org


Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
parent 0f289828

MAINTAINERS

+5 −0
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@@ -8911,6 +8911,11 @@ F: Documentation/i2c/muxes/i2c-mux-gpio.rst 
F:	drivers/i2c/muxes/i2c-mux-gpio.c

F:	include/linux/platform_data/i2c-mux-gpio.h









GENERIC GPIO RESET DRIVER









M:	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>









S:	Maintained









F:	drivers/reset/reset-gpio.c

















GENERIC HDLC (WAN) DRIVERS









M:	Krzysztof Halasa <khc@pm.waw.pl>









S:	Maintained
































drivers/reset/Kconfig



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@@ -66,6 +66,15 @@ config RESET_BRCMSTB_RESCAL







	  This enables the RESCAL reset controller for SATA, PCIe0, or PCIe1 on









	  BCM7216.



















config RESET_GPIO









	tristate "GPIO reset controller"









	help









	  This enables a generic reset controller for resets attached via









	  GPIOs.  Typically for OF platforms this driver expects "reset-gpios"









	  property.



















	  If compiled as module, it will be called reset-gpio.



















config RESET_HSDK









	bool "Synopsys HSDK Reset Driver"









	depends on HAS_IOMEM
































drivers/reset/Makefile



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@@ -11,6 +11,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o







obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o









obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o









obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o









obj-$(CONFIG_RESET_GPIO) += reset-gpio.o









obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o









obj-$(CONFIG_RESET_IMX7) += reset-imx7.o









obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o
































drivers/reset/reset-gpio.c
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// SPDX-License-Identifier: GPL-2.0



















#include <linux/gpio/consumer.h>









#include <linux/mod_devicetable.h>









#include <linux/module.h>









#include <linux/of.h>









#include <linux/platform_device.h>









#include <linux/reset-controller.h>



















struct reset_gpio_priv {









	struct reset_controller_dev rc;









	struct gpio_desc *reset;









};



















static inline struct reset_gpio_priv









*rc_to_reset_gpio(struct reset_controller_dev *rc)









{









	return container_of(rc, struct reset_gpio_priv, rc);









}



















static int reset_gpio_assert(struct reset_controller_dev *rc, unsigned long id)









{









	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);



















	gpiod_set_value_cansleep(priv->reset, 1);



















	return 0;









}



















static int reset_gpio_deassert(struct reset_controller_dev *rc,









			       unsigned long id)









{









	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);



















	gpiod_set_value_cansleep(priv->reset, 0);



















	return 0;









}



















static int reset_gpio_status(struct reset_controller_dev *rc, unsigned long id)









{









	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);



















	return gpiod_get_value_cansleep(priv->reset);









}



















static const struct reset_control_ops reset_gpio_ops = {









	.assert = reset_gpio_assert,









	.deassert = reset_gpio_deassert,









	.status = reset_gpio_status,









};



















static int reset_gpio_of_xlate(struct reset_controller_dev *rcdev,









			       const struct of_phandle_args *reset_spec)









{









	return reset_spec->args[0];









}



















static void reset_gpio_of_node_put(void *data)









{









	of_node_put(data);









}



















static int reset_gpio_probe(struct platform_device *pdev)









{









	struct device *dev = &pdev->dev;









	struct of_phandle_args *platdata = dev_get_platdata(dev);









	struct reset_gpio_priv *priv;









	int ret;



















	if (!platdata)









		return -EINVAL;



















	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);









	if (!priv)









		return -ENOMEM;



















	platform_set_drvdata(pdev, &priv->rc);



















	priv->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);









	if (IS_ERR(priv->reset))









		return dev_err_probe(dev, PTR_ERR(priv->reset),









				     "Could not get reset gpios\n");



















	priv->rc.ops = &reset_gpio_ops;









	priv->rc.owner = THIS_MODULE;









	priv->rc.dev = dev;









	priv->rc.of_args = platdata;









	ret = devm_add_action_or_reset(dev, reset_gpio_of_node_put,









				       priv->rc.of_node);









	if (ret)









		return ret;



















	/* Cells to match GPIO specifier, but it's not really used */









	priv->rc.of_reset_n_cells = 2;









	priv->rc.of_xlate = reset_gpio_of_xlate;









	priv->rc.nr_resets = 1;



















	return devm_reset_controller_register(dev, &priv->rc);









}



















static const struct platform_device_id reset_gpio_ids[] = {









	{ .name = "reset-gpio", },









	{}









};









MODULE_DEVICE_TABLE(platform, reset_gpio_ids);



















static struct platform_driver reset_gpio_driver = {









	.probe		= reset_gpio_probe,









	.id_table	= reset_gpio_ids,









	.driver	= {









		.name = "reset-gpio",









	},









};









module_platform_driver(reset_gpio_driver);



















MODULE_AUTHOR("Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>");









MODULE_DESCRIPTION("Generic GPIO reset driver");









MODULE_LICENSE("GPL");