drivers/clk/clk-gpio.c - arm/linux - Git at Google

 /*
  * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
  *
  * Authors:
  *    Jyri Sarha <jsarha@ti.com>
  *    Sergej Sawazki <ce3a@gmx.de>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * Gpio controlled clock implementation
  */

 #include <linux/clk-provider.h>
 #include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/of_gpio.h>
 #include <linux/err.h>
 #include <linux/device.h>
 #include <linux/platform_device.h>
 #include <linux/of_device.h>

 /**
  * DOC: basic gpio gated clock which can be enabled and disabled
  *      with gpio output
  * Traits of this clock:
  * prepare - clk_(un)prepare only ensures parent is (un)prepared
  * enable - clk_enable and clk_disable are functional & control gpio
  * rate - inherits rate from parent.  No clk_set_rate support
  * parent - fixed parent.  No clk_set_parent support
  */

 static int clk_gpio_gate_enable(struct clk_hw *hw)
 {
 	struct clk_gpio *clk = to_clk_gpio(hw);

 	gpiod_set_value(clk->gpiod, 1);

 	return 0;
 }

 static void clk_gpio_gate_disable(struct clk_hw *hw)
 {
 	struct clk_gpio *clk = to_clk_gpio(hw);

 	gpiod_set_value(clk->gpiod, 0);
 }

 static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
 {
 	struct clk_gpio *clk = to_clk_gpio(hw);

 	return gpiod_get_value(clk->gpiod);
 }

 const struct clk_ops clk_gpio_gate_ops = {
 	.enable = clk_gpio_gate_enable,
 	.disable = clk_gpio_gate_disable,
 	.is_enabled = clk_gpio_gate_is_enabled,
 };
 EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);

 /**
  * DOC: basic clock multiplexer which can be controlled with a gpio output
  * Traits of this clock:
  * prepare - clk_prepare only ensures that parents are prepared
  * rate - rate is only affected by parent switching.  No clk_set_rate support
  * parent - parent is adjustable through clk_set_parent
  */

 static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
 {
 	struct clk_gpio *clk = to_clk_gpio(hw);

 	return gpiod_get_value(clk->gpiod);
 }

 static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
 {
 	struct clk_gpio *clk = to_clk_gpio(hw);

 	gpiod_set_value(clk->gpiod, index);

 	return 0;
 }

 const struct clk_ops clk_gpio_mux_ops = {
 	.get_parent = clk_gpio_mux_get_parent,
 	.set_parent = clk_gpio_mux_set_parent,
 	.determine_rate = __clk_mux_determine_rate,
 };
 EXPORT_SYMBOL_GPL(clk_gpio_mux_ops);

 static struct clk_hw *clk_register_gpio(struct device *dev, const char *name,
 		const char * const *parent_names, u8 num_parents, unsigned gpio,
 		bool active_low, unsigned long flags,
 		const struct clk_ops *clk_gpio_ops)
 {
 	struct clk_gpio *clk_gpio;
 	struct clk_hw *hw;
 	struct clk_init_data init = {};
 	unsigned long gpio_flags;
 	int err;

 	if (dev)
 		clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio),	GFP_KERNEL);
 	else
 		clk_gpio = kzalloc(sizeof(*clk_gpio), GFP_KERNEL);

 	if (!clk_gpio)
 		return ERR_PTR(-ENOMEM);

 	if (active_low)
 		gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH;
 	else
 		gpio_flags = GPIOF_OUT_INIT_LOW;

 	if (dev)
 		err = devm_gpio_request_one(dev, gpio, gpio_flags, name);
 	else
 		err = gpio_request_one(gpio, gpio_flags, name);
 	if (err) {
 		if (err != -EPROBE_DEFER)
 			pr_err("%s: %s: Error requesting clock control gpio %u\n",
 					__func__, name, gpio);
 		if (!dev)
 			kfree(clk_gpio);

 		return ERR_PTR(err);
 	}

 	init.name = name;
 	init.ops = clk_gpio_ops;
 	init.flags = flags | CLK_IS_BASIC;
 	init.parent_names = parent_names;
 	init.num_parents = num_parents;

 	clk_gpio->gpiod = gpio_to_desc(gpio);
 	clk_gpio->hw.init = &init;

 	hw = &clk_gpio->hw;
 	if (dev)
 		err = devm_clk_hw_register(dev, hw);
 	else
 		err = clk_hw_register(NULL, hw);

 	if (!err)
 		return hw;

 	if (!dev) {
 		gpiod_put(clk_gpio->gpiod);
 		kfree(clk_gpio);
 	}

 	return ERR_PTR(err);
 }

 /**
  * clk_hw_register_gpio_gate - register a gpio clock gate with the clock
  * framework
  * @dev: device that is registering this clock
  * @name: name of this clock
  * @parent_name: name of this clock's parent
  * @gpio: gpio number to gate this clock
  * @active_low: true if gpio should be set to 0 to enable clock
  * @flags: clock flags
  */
 struct clk_hw *clk_hw_register_gpio_gate(struct device *dev, const char *name,
 		const char *parent_name, unsigned gpio, bool active_low,
 		unsigned long flags)
 {
 	return clk_register_gpio(dev, name,
 			(parent_name ? &parent_name : NULL),
 			(parent_name ? 1 : 0), gpio, active_low, flags,
 			&clk_gpio_gate_ops);
 }
 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_gate);

 struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
 		const char *parent_name, unsigned gpio, bool active_low,
 		unsigned long flags)
 {
 	struct clk_hw *hw;

 	hw = clk_hw_register_gpio_gate(dev, name, parent_name, gpio, active_low,
 				       flags);
 	if (IS_ERR(hw))
 		return ERR_CAST(hw);
 	return hw->clk;
 }
 EXPORT_SYMBOL_GPL(clk_register_gpio_gate);

 /**
  * clk_hw_register_gpio_mux - register a gpio clock mux with the clock framework
  * @dev: device that is registering this clock
  * @name: name of this clock
  * @parent_names: names of this clock's parents
  * @num_parents: number of parents listed in @parent_names
  * @gpio: gpio number to gate this clock
  * @active_low: true if gpio should be set to 0 to enable clock
  * @flags: clock flags
  */
 struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, const char *name,
 		const char * const *parent_names, u8 num_parents, unsigned gpio,
 		bool active_low, unsigned long flags)
 {
 	if (num_parents != 2) {
 		pr_err("mux-clock %s must have 2 parents\n", name);
 		return ERR_PTR(-EINVAL);
 	}

 	return clk_register_gpio(dev, name, parent_names, num_parents,
 			gpio, active_low, flags, &clk_gpio_mux_ops);
 }
 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_mux);

 struct clk *clk_register_gpio_mux(struct device *dev, const char *name,
 		const char * const *parent_names, u8 num_parents, unsigned gpio,
 		bool active_low, unsigned long flags)
 {
 	struct clk_hw *hw;

 	hw = clk_hw_register_gpio_mux(dev, name, parent_names, num_parents,
 			gpio, active_low, flags);
 	if (IS_ERR(hw))
 		return ERR_CAST(hw);
 	return hw->clk;
 }
 EXPORT_SYMBOL_GPL(clk_register_gpio_mux);

 static int gpio_clk_driver_probe(struct platform_device *pdev)
 {
 	struct device_node *node = pdev->dev.of_node;
 	const char **parent_names, *gpio_name;
 	unsigned int num_parents;
 	int gpio;
 	enum of_gpio_flags of_flags;
 	struct clk *clk;
 	bool active_low, is_mux;

 	num_parents = of_clk_get_parent_count(node);
 	if (num_parents) {
 		parent_names = devm_kcalloc(&pdev->dev, num_parents,
 					    sizeof(char *), GFP_KERNEL);
 		if (!parent_names)
 			return -ENOMEM;

 		of_clk_parent_fill(node, parent_names, num_parents);
 	} else {
 		parent_names = NULL;
 	}

 	is_mux = of_device_is_compatible(node, "gpio-mux-clock");

 	gpio_name = is_mux ? "select-gpios" : "enable-gpios";
 	gpio = of_get_named_gpio_flags(node, gpio_name, 0, &of_flags);
 	if (gpio < 0) {
 		if (gpio == -EPROBE_DEFER)
 			pr_debug("%s: %s: GPIOs not yet available, retry later\n",
 					node->name, __func__);
 		else
 			pr_err("%s: %s: Can't get '%s' DT property\n",
 					node->name, __func__,
 					gpio_name);
 		return gpio;
 	}

 	active_low = of_flags & OF_GPIO_ACTIVE_LOW;

 	if (is_mux)
 		clk = clk_register_gpio_mux(&pdev->dev, node->name,
 				parent_names, num_parents, gpio, active_low, 0);
 	else
 		clk = clk_register_gpio_gate(&pdev->dev, node->name,
 				parent_names ?  parent_names[0] : NULL, gpio,
 				active_low, 0);
 	if (IS_ERR(clk))
 		return PTR_ERR(clk);

 	return of_clk_add_provider(node, of_clk_src_simple_get, clk);
 }

 static const struct of_device_id gpio_clk_match_table[] = {
 	{ .compatible = "gpio-mux-clock" },
 	{ .compatible = "gpio-gate-clock" },
 	{ }
 };

 static struct platform_driver gpio_clk_driver = {
 	.probe		= gpio_clk_driver_probe,
 	.driver		= {
 		.name	= "gpio-clk",
 		.of_match_table = gpio_clk_match_table,
 	},
 };
 builtin_platform_driver(gpio_clk_driver);
	/*
	* Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
	*
	* Authors:
	* Jyri Sarha <jsarha@ti.com>
	* Sergej Sawazki <ce3a@gmx.de>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* Gpio controlled clock implementation
	*/

	#include <linux/clk-provider.h>
	#include <linux/export.h>
	#include <linux/slab.h>
	#include <linux/gpio.h>
	#include <linux/gpio/consumer.h>
	#include <linux/of_gpio.h>
	#include <linux/err.h>
	#include <linux/device.h>
	#include <linux/platform_device.h>
	#include <linux/of_device.h>

	/**
	* DOC: basic gpio gated clock which can be enabled and disabled
	* with gpio output
	* Traits of this clock:
	* prepare - clk_(un)prepare only ensures parent is (un)prepared
	* enable - clk_enable and clk_disable are functional & control gpio
	* rate - inherits rate from parent. No clk_set_rate support
	* parent - fixed parent. No clk_set_parent support
	*/

	static int clk_gpio_gate_enable(struct clk_hw *hw)
	{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value(clk->gpiod, 1);

	return 0;
	}

	static void clk_gpio_gate_disable(struct clk_hw *hw)
	{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value(clk->gpiod, 0);
	}

	static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
	{
	struct clk_gpio *clk = to_clk_gpio(hw);

	return gpiod_get_value(clk->gpiod);
	}

	const struct clk_ops clk_gpio_gate_ops = {
	.enable = clk_gpio_gate_enable,
	.disable = clk_gpio_gate_disable,
	.is_enabled = clk_gpio_gate_is_enabled,
	};
	EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);

	/**
	* DOC: basic clock multiplexer which can be controlled with a gpio output
	* Traits of this clock:
	* prepare - clk_prepare only ensures that parents are prepared
	* rate - rate is only affected by parent switching. No clk_set_rate support
	* parent - parent is adjustable through clk_set_parent
	*/

	static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
	{
	struct clk_gpio *clk = to_clk_gpio(hw);

	return gpiod_get_value(clk->gpiod);
	}

	static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
	{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value(clk->gpiod, index);

	return 0;
	}

	const struct clk_ops clk_gpio_mux_ops = {
	.get_parent = clk_gpio_mux_get_parent,
	.set_parent = clk_gpio_mux_set_parent,
	.determine_rate = __clk_mux_determine_rate,
	};
	EXPORT_SYMBOL_GPL(clk_gpio_mux_ops);

	static struct clk_hw clk_register_gpio(struct device dev, const char *name,
	const char * const *parent_names, u8 num_parents, unsigned gpio,
	bool active_low, unsigned long flags,
	const struct clk_ops *clk_gpio_ops)
	{
	struct clk_gpio *clk_gpio;
	struct clk_hw *hw;
	struct clk_init_data init = {};
	unsigned long gpio_flags;
	int err;

	if (dev)
	clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
	else
	clk_gpio = kzalloc(sizeof(*clk_gpio), GFP_KERNEL);

	if (!clk_gpio)
	return ERR_PTR(-ENOMEM);

	if (active_low)
	gpio_flags = GPIOF_ACTIVE_LOW \| GPIOF_OUT_INIT_HIGH;
	else
	gpio_flags = GPIOF_OUT_INIT_LOW;

	if (dev)
	err = devm_gpio_request_one(dev, gpio, gpio_flags, name);
	else
	err = gpio_request_one(gpio, gpio_flags, name);
	if (err) {
	if (err != -EPROBE_DEFER)
	pr_err("%s: %s: Error requesting clock control gpio %u\n",
	__func__, name, gpio);
	if (!dev)
	kfree(clk_gpio);

	return ERR_PTR(err);
	}

	init.name = name;
	init.ops = clk_gpio_ops;
	init.flags = flags \| CLK_IS_BASIC;
	init.parent_names = parent_names;
	init.num_parents = num_parents;

	clk_gpio->gpiod = gpio_to_desc(gpio);
	clk_gpio->hw.init = &init;

	hw = &clk_gpio->hw;
	if (dev)
	err = devm_clk_hw_register(dev, hw);
	else
	err = clk_hw_register(NULL, hw);

	if (!err)
	return hw;

	if (!dev) {
	gpiod_put(clk_gpio->gpiod);
	kfree(clk_gpio);
	}

	return ERR_PTR(err);
	}

	/**
	* clk_hw_register_gpio_gate - register a gpio clock gate with the clock
	* framework
	* @dev: device that is registering this clock
	* @name: name of this clock
	* @parent_name: name of this clock's parent
	* @gpio: gpio number to gate this clock
	* @active_low: true if gpio should be set to 0 to enable clock
	* @flags: clock flags
	*/
	struct clk_hw clk_hw_register_gpio_gate(struct device dev, const char *name,
	const char *parent_name, unsigned gpio, bool active_low,
	unsigned long flags)
	{
	return clk_register_gpio(dev, name,
	(parent_name ? &parent_name : NULL),
	(parent_name ? 1 : 0), gpio, active_low, flags,
	&clk_gpio_gate_ops);
	}
	EXPORT_SYMBOL_GPL(clk_hw_register_gpio_gate);

	struct clk clk_register_gpio_gate(struct device dev, const char *name,
	const char *parent_name, unsigned gpio, bool active_low,
	unsigned long flags)
	{
	struct clk_hw *hw;

	hw = clk_hw_register_gpio_gate(dev, name, parent_name, gpio, active_low,
	flags);
	if (IS_ERR(hw))
	return ERR_CAST(hw);
	return hw->clk;
	}
	EXPORT_SYMBOL_GPL(clk_register_gpio_gate);

	/**
	* clk_hw_register_gpio_mux - register a gpio clock mux with the clock framework
	* @dev: device that is registering this clock
	* @name: name of this clock
	* @parent_names: names of this clock's parents
	* @num_parents: number of parents listed in @parent_names
	* @gpio: gpio number to gate this clock
	* @active_low: true if gpio should be set to 0 to enable clock
	* @flags: clock flags
	*/
	struct clk_hw clk_hw_register_gpio_mux(struct device dev, const char *name,
	const char * const *parent_names, u8 num_parents, unsigned gpio,
	bool active_low, unsigned long flags)
	{
	if (num_parents != 2) {
	pr_err("mux-clock %s must have 2 parents\n", name);
	return ERR_PTR(-EINVAL);
	}

	return clk_register_gpio(dev, name, parent_names, num_parents,
	gpio, active_low, flags, &clk_gpio_mux_ops);
	}
	EXPORT_SYMBOL_GPL(clk_hw_register_gpio_mux);

	struct clk clk_register_gpio_mux(struct device dev, const char *name,
	const char * const *parent_names, u8 num_parents, unsigned gpio,
	bool active_low, unsigned long flags)
	{
	struct clk_hw *hw;

	hw = clk_hw_register_gpio_mux(dev, name, parent_names, num_parents,
	gpio, active_low, flags);
	if (IS_ERR(hw))
	return ERR_CAST(hw);
	return hw->clk;
	}
	EXPORT_SYMBOL_GPL(clk_register_gpio_mux);

	static int gpio_clk_driver_probe(struct platform_device *pdev)
	{
	struct device_node *node = pdev->dev.of_node;
	const char *parent_names, gpio_name;
	unsigned int num_parents;
	int gpio;
	enum of_gpio_flags of_flags;
	struct clk *clk;
	bool active_low, is_mux;

	num_parents = of_clk_get_parent_count(node);
	if (num_parents) {
	parent_names = devm_kcalloc(&pdev->dev, num_parents,
	sizeof(char *), GFP_KERNEL);
	if (!parent_names)
	return -ENOMEM;

	of_clk_parent_fill(node, parent_names, num_parents);
	} else {
	parent_names = NULL;
	}

	is_mux = of_device_is_compatible(node, "gpio-mux-clock");

	gpio_name = is_mux ? "select-gpios" : "enable-gpios";
	gpio = of_get_named_gpio_flags(node, gpio_name, 0, &of_flags);
	if (gpio < 0) {
	if (gpio == -EPROBE_DEFER)
	pr_debug("%s: %s: GPIOs not yet available, retry later\n",
	node->name, __func__);
	else
	pr_err("%s: %s: Can't get '%s' DT property\n",
	node->name, __func__,
	gpio_name);
	return gpio;
	}

	active_low = of_flags & OF_GPIO_ACTIVE_LOW;

	if (is_mux)
	clk = clk_register_gpio_mux(&pdev->dev, node->name,
	parent_names, num_parents, gpio, active_low, 0);
	else
	clk = clk_register_gpio_gate(&pdev->dev, node->name,
	parent_names ? parent_names[0] : NULL, gpio,
	active_low, 0);
	if (IS_ERR(clk))
	return PTR_ERR(clk);

	return of_clk_add_provider(node, of_clk_src_simple_get, clk);
	}

	static const struct of_device_id gpio_clk_match_table[] = {
	{ .compatible = "gpio-mux-clock" },
	{ .compatible = "gpio-gate-clock" },
	{ }
	};

	static struct platform_driver gpio_clk_driver = {
	.probe = gpio_clk_driver_probe,
	.driver = {
	.name = "gpio-clk",
	.of_match_table = gpio_clk_match_table,
	},
	};
	builtin_platform_driver(gpio_clk_driver);