clk: add gpio gated clock

Binding for simple gpio gated clock.

This binding uses the common clock binding[1].

[1] Documentation/devicetree/bindings/clock/clock-bindings.txt

Required properties:

- compatible : shall be "gpio-gate-clock".

- #clock-cells : from common clock binding; shall be set to 0.

- enable-gpios : GPIO reference for enabling and disabling the clock.

Optional properties:

- clocks: Maximum of one parent clock is supported.

Example:

	clock {

		compatible = "gpio-gate-clock";

		clocks = <&parentclk>;

		#clock-cells = <0>;

		enable-gpios = <&gpio 1 GPIO_ACTIVE_HIGH>;

	};

obj-$(CONFIG_COMMON_CLK)	+= clk-mux.o

obj-$(CONFIG_COMMON_CLK)	+= clk-composite.o

obj-$(CONFIG_COMMON_CLK)	+= clk-fractional-divider.o

obj-$(CONFIG_COMMON_CLK)	+= clk-gpio-gate.o

ifeq ($(CONFIG_OF), y)

obj-$(CONFIG_COMMON_CLK)	+= clk-conf.o

endif

/*

 * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com

 * Author: Jyri Sarha <jsarha@ti.com>

 *

 * 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 gated clock implementation

 */

#include <linux/clk-provider.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/gpio.h>

#include <linux/of_gpio.h>

#include <linux/err.h>

#include <linux/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

 */

#define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)

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);

/**

 * clk_register_gpio - register a gpip clock with the clock framework

 * @dev: device that is registering this clock

 * @name: name of this clock

 * @parent_name: name of this clock's parent

 * @gpiod: gpio descriptor to gate this clock

 */

struct clk *clk_register_gpio_gate(struct device *dev, const char *name,

		const char *parent_name, struct gpio_desc *gpiod,

		unsigned long flags)

{

	struct clk_gpio *clk_gpio = NULL;

	struct clk *clk = ERR_PTR(-EINVAL);

	struct clk_init_data init = { NULL };

	unsigned long gpio_flags;

	int err;

	if (gpiod_is_active_low(gpiod))

		gpio_flags = GPIOF_OUT_INIT_HIGH;

	else

		gpio_flags = GPIOF_OUT_INIT_LOW;

	if (dev)

		err = devm_gpio_request_one(dev, desc_to_gpio(gpiod),

					    gpio_flags, name);

	else

		err = gpio_request_one(desc_to_gpio(gpiod), gpio_flags, name);

	if (err) {

		pr_err("%s: %s: Error requesting clock control gpio %u\n",

		       __func__, name, desc_to_gpio(gpiod));

		return ERR_PTR(err);

	}

	if (dev)

		clk_gpio = devm_kzalloc(dev, sizeof(struct clk_gpio),

					GFP_KERNEL);

	else

		clk_gpio = kzalloc(sizeof(struct clk_gpio), GFP_KERNEL);

	if (!clk_gpio) {

		clk = ERR_PTR(-ENOMEM);

		goto clk_register_gpio_gate_err;

	}

	init.name = name;

	init.ops = &clk_gpio_gate_ops;

	init.flags = flags | CLK_IS_BASIC;

	init.parent_names = (parent_name ? &parent_name : NULL);

	init.num_parents = (parent_name ? 1 : 0);

	clk_gpio->gpiod = gpiod;

	clk_gpio->hw.init = &init;

	clk = clk_register(dev, &clk_gpio->hw);

	if (!IS_ERR(clk))

		return clk;

	if (!dev)

		kfree(clk_gpio);

clk_register_gpio_gate_err:

	gpiod_put(gpiod);

	return clk;

}

EXPORT_SYMBOL_GPL(clk_register_gpio_gate);

#ifdef CONFIG_OF

/**

 * The clk_register_gpio_gate has to be delayed, because the EPROBE_DEFER

 * can not be handled properly at of_clk_init() call time.

 */

struct clk_gpio_gate_delayed_register_data {

	struct device_node *node;

	struct mutex lock;

	struct clk *clk;

};

static struct clk *of_clk_gpio_gate_delayed_register_get(

		struct of_phandle_args *clkspec,

		void *_data)

{

	struct clk_gpio_gate_delayed_register_data *data = _data;

	struct clk *clk;

	const char *clk_name = data->node->name;

	const char *parent_name;

	struct gpio_desc *gpiod;

	int gpio;

	mutex_lock(&data->lock);

	if (data->clk) {

		mutex_unlock(&data->lock);

		return data->clk;

	}

	gpio = of_get_named_gpio_flags(data->node, "enable-gpios", 0, NULL);

	if (gpio < 0) {

		mutex_unlock(&data->lock);

		if (gpio != -EPROBE_DEFER)

			pr_err("%s: %s: Can't get 'enable-gpios' DT property\n",

			       __func__, clk_name);

		return ERR_PTR(gpio);

	}

	gpiod = gpio_to_desc(gpio);

	parent_name = of_clk_get_parent_name(data->node, 0);

	clk = clk_register_gpio_gate(NULL, clk_name, parent_name, gpiod, 0);

	if (IS_ERR(clk)) {

		mutex_unlock(&data->lock);

		return clk;

	}

	data->clk = clk;

	mutex_unlock(&data->lock);

	return clk;

}

/**

 * of_gpio_gate_clk_setup() - Setup function for gpio controlled clock

 */

void __init of_gpio_gate_clk_setup(struct device_node *node)

{

	struct clk_gpio_gate_delayed_register_data *data;

	data = kzalloc(sizeof(struct clk_gpio_gate_delayed_register_data),

		       GFP_KERNEL);

	if (!data)

		return;

	data->node = node;

	mutex_init(&data->lock);

	of_clk_add_provider(node, of_clk_gpio_gate_delayed_register_get, data);

}

EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup);

CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup);

#endif

		struct clk_hw *gate_hw, const struct clk_ops *gate_ops,

		unsigned long flags);

/***

 * struct clk_gpio_gate - gpio gated clock

 *

 * @hw:		handle between common and hardware-specific interfaces

 * @gpiod:	gpio descriptor

 *

 * Clock with a gpio control for enabling and disabling the parent clock.

 * Implements .enable, .disable and .is_enabled

 */

struct clk_gpio {

	struct clk_hw	hw;

	struct gpio_desc *gpiod;

};

extern const struct clk_ops clk_gpio_gate_ops;

struct clk *clk_register_gpio_gate(struct device *dev, const char *name,

		const char *parent_name, struct gpio_desc *gpio,

		unsigned long flags);

void of_gpio_clk_gate_setup(struct device_node *node);

/**

 * clk_register - allocate a new clock, register it and return an opaque cookie

 * @dev: device that is registering this clock