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/*
* Copyright (C) 2012 Texas Instruments
* 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 controlled 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 controlled 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_enable(struct clk_hw *hw)
{
struct clk_gpio *gpio = to_clk_gpio(hw);
int value = gpio->active_low ? 0 : 1;
gpio_set_value(gpio->gpio, value);
return 0;
}
static void clk_gpio_disable(struct clk_hw *hw)
{
struct clk_gpio *gpio = to_clk_gpio(hw);
int value = gpio->active_low ? 1 : 0;
gpio_set_value(gpio->gpio, value);
}
static int clk_gpio_is_enabled(struct clk_hw *hw)
{
struct clk_gpio *gpio = to_clk_gpio(hw);
int value = gpio_get_value(gpio->gpio);
return gpio->active_low ? !value : value;
}
const struct clk_ops clk_gpio_ops = {
.enable = clk_gpio_enable,
.disable = clk_gpio_disable,
.is_enabled = clk_gpio_is_enabled,
};
EXPORT_SYMBOL_GPL(clk_gpio_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
* @flags: framework-specific flags for this clock
* @gpio: gpio to control this clock
* @active_low: gpio polarity
*/
struct clk *clk_register_gpio(struct device *dev, const char *name,
const char *parent_name, unsigned long flags,
unsigned int gpio, bool active_low)
{
struct clk_gpio *clk_gpio;
struct clk *clk;
struct clk_init_data init = { NULL };
unsigned long gpio_flags;
int err;
if (active_low)
gpio_flags = GPIOF_OUT_INIT_LOW;
else
gpio_flags = GPIOF_OUT_INIT_HIGH;
if (dev)
err = devm_gpio_request_one(dev, gpio, gpio_flags, name);
else
err = gpio_request_one(gpio, gpio_flags, name);
if (err) {
pr_err("%s: %s: Error requesting clock control gpio %u\n",
__func__, name, gpio);
goto clk_register_gpio_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) {
pr_err("%s: %s: could not allocate gpio clk\n", __func__, name);
goto clk_register_gpio_err;
}
init.name = name;
init.ops = &clk_gpio_ops;
init.flags = flags | CLK_IS_BASIC;
init.parent_names = (parent_name ? &parent_name : NULL);
init.num_parents = (parent_name ? 1 : 0);
clk_gpio->gpio = gpio;
clk_gpio->active_low = active_low;
clk_gpio->hw.init = &init;
clk = clk_register(dev, &clk_gpio->hw);
if (!IS_ERR(clk))
return clk;
err = PTR_ERR(clk);
if (!dev)
kfree(clk_gpio);
clk_register_gpio_err:
if (!dev)
gpio_free(gpio);
return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(clk_register_gpio);
#ifdef CONFIG_OF
/**
* The clk_register_gpio has to be delayed, because the EPROBE_DEFER
* can not be handled properly at of_clk_init() call time.
*/
struct clk_gpio_delayed_register_data {
struct device_node *node;
struct mutex lock;
struct clk *clk;
};
struct clk *of_clk_gpio_delayed_register_get(struct of_phandle_args *clkspec,
void *_data)
{
struct clk_gpio_delayed_register_data *data =
(struct clk_gpio_delayed_register_data *) _data;
struct clk *clk;
const char *clk_name = data->node->name;
const char *parent_name;
enum of_gpio_flags gpio_flags;
int gpio;
bool active_low;
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,
&gpio_flags);
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);
}
active_low = gpio_flags & OF_GPIO_ACTIVE_LOW;
parent_name = of_clk_get_parent_name(data->node, 0);
clk = clk_register_gpio(NULL, clk_name, parent_name, 0,
gpio, active_low);
if (IS_ERR(clk)) {
mutex_unlock(&data->lock);
return clk;
}
data->clk = clk;
mutex_unlock(&data->lock);
return clk;
}
/**
* of_gpio_clk_setup() - Setup function for gpio controlled clock
*/
void __init of_gpio_clk_setup(struct device_node *node)
{
struct clk_gpio_delayed_register_data *data;
data = kzalloc(sizeof(struct clk_gpio_delayed_register_data),
GFP_KERNEL);
if (!data) {
pr_err("%s: could not allocate gpio clk\n", __func__);
return;
}
data->node = node;
mutex_init(&data->lock);
of_clk_add_provider(node, of_clk_gpio_delayed_register_get, data);
}
EXPORT_SYMBOL_GPL(of_gpio_clk_setup);
CLK_OF_DECLARE(gpio_clk, "gpio-clock", of_gpio_clk_setup);
#endif
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