// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com
*
* Authors:
* Jyri Sarha <[email protected]>
* Sergej Sawazki <[email protected]>
*
* Gpio controlled clock implementation
*/
#include <linux/clk-provider.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/gpio/consumer.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/platform_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
*/
/**
* struct clk_gpio - 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
* or switching between two parents by asserting or deasserting the gpio.
*
* Implements .enable, .disable and .is_enabled or
* .get_parent, .set_parent and .determine_rate depending on which clk_ops
* is used.
*/
struct clk_gpio {
struct clk_hw hw;
struct gpio_desc *gpiod;
};
#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);
}
static 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,
};
static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
{
struct clk_gpio *clk = to_clk_gpio(hw);
gpiod_set_value_cansleep(clk->gpiod, 1);
return 0;
}
static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
{
struct clk_gpio *clk = to_clk_gpio(hw);
gpiod_set_value_cansleep(clk->gpiod, 0);
}
static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
{
struct clk_gpio *clk = to_clk_gpio(hw);
return gpiod_get_value_cansleep(clk->gpiod);
}
static const struct clk_ops clk_sleeping_gpio_gate_ops = {
.prepare = clk_sleeping_gpio_gate_prepare,
.unprepare = clk_sleeping_gpio_gate_unprepare,
.is_prepared = clk_sleeping_gpio_gate_is_prepared,
};
/**
* 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_cansleep(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_cansleep(clk->gpiod, index);
return 0;
}
static 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,
};
static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents,
struct gpio_desc *gpiod,
const struct clk_ops *clk_gpio_ops)
{
struct clk_gpio *clk_gpio;
struct clk_hw *hw;
struct clk_init_data init = {};
int err;
const struct clk_parent_data gpio_parent_data[] = {
{ .index = 0 },
{ .index = 1 },
};
clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
if (!clk_gpio)
return ERR_PTR(-ENOMEM);
init.name = dev->of_node->name;
init.ops = clk_gpio_ops;
init.parent_data = gpio_parent_data;
init.num_parents = num_parents;
init.flags = CLK_SET_RATE_PARENT;
clk_gpio->gpiod = gpiod;
clk_gpio->hw.init = &init;
hw = &clk_gpio->hw;
err = devm_clk_hw_register(dev, hw);
if (err)
return ERR_PTR(err);
return hw;
}
static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev,
int num_parents,
struct gpio_desc *gpiod)
{
const struct clk_ops *ops;
if (gpiod_cansleep(gpiod))
ops = &clk_sleeping_gpio_gate_ops;
else
ops = &clk_gpio_gate_ops;
return clk_register_gpio(dev, num_parents, gpiod, ops);
}
static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev,
struct gpio_desc *gpiod)
{
return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops);
}
static int gpio_clk_driver_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *node = dev->of_node;
const char *gpio_name;
unsigned int num_parents;
struct gpio_desc *gpiod;
struct clk_hw *hw;
bool is_mux;
int ret;
is_mux = of_device_is_compatible(node, "gpio-mux-clock");
num_parents = of_clk_get_parent_count(node);
if (is_mux && num_parents != 2) {
dev_err(dev, "mux-clock must have 2 parents\n");
return -EINVAL;
}
gpio_name = is_mux ? "select" : "enable";
gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW);
if (IS_ERR(gpiod)) {
ret = PTR_ERR(gpiod);
if (ret == -EPROBE_DEFER)
pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
node, __func__);
else
pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n",
node, __func__,
gpio_name);
return ret;
}
if (is_mux)
hw = clk_hw_register_gpio_mux(dev, gpiod);
else
hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod);
if (IS_ERR(hw))
return PTR_ERR(hw);
return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
}
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);
Codebase Browser
linux