300 lines
7.8 KiB
C
300 lines
7.8 KiB
C
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/*
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* Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
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*
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* Authors:
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* Jyri Sarha <jsarha@ti.com>
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* Sergej Sawazki <ce3a@gmx.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Gpio controlled clock implementation
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*/
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#include <linux/clk-provider.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/gpio.h>
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#include <linux/gpio/consumer.h>
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#include <linux/of_gpio.h>
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#include <linux/err.h>
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#include <linux/device.h>
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#include <linux/platform_device.h>
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#include <linux/of_device.h>
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/**
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* DOC: basic gpio gated clock which can be enabled and disabled
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* with gpio output
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* Traits of this clock:
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* prepare - clk_(un)prepare only ensures parent is (un)prepared
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* enable - clk_enable and clk_disable are functional & control gpio
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* rate - inherits rate from parent. No clk_set_rate support
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* parent - fixed parent. No clk_set_parent support
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*/
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static int clk_gpio_gate_enable(struct clk_hw *hw)
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{
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struct clk_gpio *clk = to_clk_gpio(hw);
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gpiod_set_value(clk->gpiod, 1);
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return 0;
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}
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static void clk_gpio_gate_disable(struct clk_hw *hw)
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{
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struct clk_gpio *clk = to_clk_gpio(hw);
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gpiod_set_value(clk->gpiod, 0);
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}
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static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
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{
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struct clk_gpio *clk = to_clk_gpio(hw);
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return gpiod_get_value(clk->gpiod);
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}
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const struct clk_ops clk_gpio_gate_ops = {
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.enable = clk_gpio_gate_enable,
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.disable = clk_gpio_gate_disable,
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.is_enabled = clk_gpio_gate_is_enabled,
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};
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EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);
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/**
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* DOC: basic clock multiplexer which can be controlled with a gpio output
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* Traits of this clock:
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* prepare - clk_prepare only ensures that parents are prepared
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* rate - rate is only affected by parent switching. No clk_set_rate support
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* parent - parent is adjustable through clk_set_parent
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*/
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static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
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{
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struct clk_gpio *clk = to_clk_gpio(hw);
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return gpiod_get_value(clk->gpiod);
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}
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static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
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{
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struct clk_gpio *clk = to_clk_gpio(hw);
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gpiod_set_value(clk->gpiod, index);
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return 0;
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}
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const struct clk_ops clk_gpio_mux_ops = {
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.get_parent = clk_gpio_mux_get_parent,
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.set_parent = clk_gpio_mux_set_parent,
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.determine_rate = __clk_mux_determine_rate,
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};
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EXPORT_SYMBOL_GPL(clk_gpio_mux_ops);
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static struct clk_hw *clk_register_gpio(struct device *dev, const char *name,
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const char * const *parent_names, u8 num_parents, unsigned gpio,
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bool active_low, unsigned long flags,
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const struct clk_ops *clk_gpio_ops)
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{
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struct clk_gpio *clk_gpio;
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struct clk_hw *hw;
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struct clk_init_data init = {};
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unsigned long gpio_flags;
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int err;
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if (dev)
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clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
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else
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clk_gpio = kzalloc(sizeof(*clk_gpio), GFP_KERNEL);
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if (!clk_gpio)
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return ERR_PTR(-ENOMEM);
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if (active_low)
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gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH;
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else
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gpio_flags = GPIOF_OUT_INIT_LOW;
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if (dev)
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err = devm_gpio_request_one(dev, gpio, gpio_flags, name);
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else
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err = gpio_request_one(gpio, gpio_flags, name);
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if (err) {
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if (err != -EPROBE_DEFER)
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pr_err("%s: %s: Error requesting clock control gpio %u\n",
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__func__, name, gpio);
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if (!dev)
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kfree(clk_gpio);
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return ERR_PTR(err);
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}
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init.name = name;
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init.ops = clk_gpio_ops;
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init.flags = flags | CLK_IS_BASIC;
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init.parent_names = parent_names;
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init.num_parents = num_parents;
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clk_gpio->gpiod = gpio_to_desc(gpio);
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clk_gpio->hw.init = &init;
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hw = &clk_gpio->hw;
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if (dev)
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err = devm_clk_hw_register(dev, hw);
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else
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err = clk_hw_register(NULL, hw);
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if (!err)
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return hw;
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if (!dev) {
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gpiod_put(clk_gpio->gpiod);
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kfree(clk_gpio);
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}
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return ERR_PTR(err);
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}
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/**
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* clk_hw_register_gpio_gate - register a gpio clock gate with the clock
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* framework
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* @dev: device that is registering this clock
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* @name: name of this clock
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* @parent_name: name of this clock's parent
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* @gpio: gpio number to gate this clock
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* @active_low: true if gpio should be set to 0 to enable clock
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* @flags: clock flags
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*/
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struct clk_hw *clk_hw_register_gpio_gate(struct device *dev, const char *name,
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const char *parent_name, unsigned gpio, bool active_low,
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unsigned long flags)
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{
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return clk_register_gpio(dev, name,
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(parent_name ? &parent_name : NULL),
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(parent_name ? 1 : 0), gpio, active_low, flags,
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&clk_gpio_gate_ops);
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}
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EXPORT_SYMBOL_GPL(clk_hw_register_gpio_gate);
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struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
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const char *parent_name, unsigned gpio, bool active_low,
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unsigned long flags)
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{
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struct clk_hw *hw;
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hw = clk_hw_register_gpio_gate(dev, name, parent_name, gpio, active_low,
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flags);
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if (IS_ERR(hw))
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return ERR_CAST(hw);
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return hw->clk;
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}
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EXPORT_SYMBOL_GPL(clk_register_gpio_gate);
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/**
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* clk_hw_register_gpio_mux - register a gpio clock mux with the clock framework
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* @dev: device that is registering this clock
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* @name: name of this clock
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* @parent_names: names of this clock's parents
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* @num_parents: number of parents listed in @parent_names
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* @gpio: gpio number to gate this clock
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* @active_low: true if gpio should be set to 0 to enable clock
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* @flags: clock flags
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*/
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struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, const char *name,
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const char * const *parent_names, u8 num_parents, unsigned gpio,
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bool active_low, unsigned long flags)
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{
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if (num_parents != 2) {
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pr_err("mux-clock %s must have 2 parents\n", name);
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return ERR_PTR(-EINVAL);
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}
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return clk_register_gpio(dev, name, parent_names, num_parents,
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gpio, active_low, flags, &clk_gpio_mux_ops);
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}
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EXPORT_SYMBOL_GPL(clk_hw_register_gpio_mux);
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struct clk *clk_register_gpio_mux(struct device *dev, const char *name,
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const char * const *parent_names, u8 num_parents, unsigned gpio,
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bool active_low, unsigned long flags)
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{
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struct clk_hw *hw;
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hw = clk_hw_register_gpio_mux(dev, name, parent_names, num_parents,
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gpio, active_low, flags);
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if (IS_ERR(hw))
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return ERR_CAST(hw);
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return hw->clk;
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}
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EXPORT_SYMBOL_GPL(clk_register_gpio_mux);
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static int gpio_clk_driver_probe(struct platform_device *pdev)
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{
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struct device_node *node = pdev->dev.of_node;
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const char **parent_names, *gpio_name;
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unsigned int num_parents;
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int gpio;
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enum of_gpio_flags of_flags;
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struct clk *clk;
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bool active_low, is_mux;
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num_parents = of_clk_get_parent_count(node);
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if (num_parents) {
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parent_names = devm_kcalloc(&pdev->dev, num_parents,
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sizeof(char *), GFP_KERNEL);
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if (!parent_names)
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return -ENOMEM;
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of_clk_parent_fill(node, parent_names, num_parents);
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} else {
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parent_names = NULL;
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}
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is_mux = of_device_is_compatible(node, "gpio-mux-clock");
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gpio_name = is_mux ? "select-gpios" : "enable-gpios";
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gpio = of_get_named_gpio_flags(node, gpio_name, 0, &of_flags);
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if (gpio < 0) {
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if (gpio == -EPROBE_DEFER)
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pr_debug("%s: %s: GPIOs not yet available, retry later\n",
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node->name, __func__);
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else
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pr_err("%s: %s: Can't get '%s' DT property\n",
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node->name, __func__,
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gpio_name);
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return gpio;
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}
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active_low = of_flags & OF_GPIO_ACTIVE_LOW;
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if (is_mux)
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clk = clk_register_gpio_mux(&pdev->dev, node->name,
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parent_names, num_parents, gpio, active_low, 0);
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else
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clk = clk_register_gpio_gate(&pdev->dev, node->name,
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parent_names ? parent_names[0] : NULL, gpio,
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active_low, 0);
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if (IS_ERR(clk))
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return PTR_ERR(clk);
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return of_clk_add_provider(node, of_clk_src_simple_get, clk);
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}
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static const struct of_device_id gpio_clk_match_table[] = {
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{ .compatible = "gpio-mux-clock" },
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{ .compatible = "gpio-gate-clock" },
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{ }
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};
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static struct platform_driver gpio_clk_driver = {
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.probe = gpio_clk_driver_probe,
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.driver = {
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.name = "gpio-clk",
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.of_match_table = gpio_clk_match_table,
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},
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};
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builtin_platform_driver(gpio_clk_driver);
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