250 lines
6.0 KiB
C
250 lines
6.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://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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* 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/consumer.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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/**
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* struct clk_gpio - gpio gated clock
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*
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* @hw: handle between common and hardware-specific interfaces
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* @gpiod: gpio descriptor
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*
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* Clock with a gpio control for enabling and disabling the parent clock
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* or switching between two parents by asserting or deasserting the gpio.
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*
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* Implements .enable, .disable and .is_enabled or
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* .get_parent, .set_parent and .determine_rate depending on which clk_ops
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* is used.
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*/
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struct clk_gpio {
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struct clk_hw hw;
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struct gpio_desc *gpiod;
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};
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#define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)
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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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static 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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static int clk_sleeping_gpio_gate_prepare(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_cansleep(clk->gpiod, 1);
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return 0;
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}
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static void clk_sleeping_gpio_gate_unprepare(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_cansleep(clk->gpiod, 0);
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}
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static int clk_sleeping_gpio_gate_is_prepared(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_cansleep(clk->gpiod);
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}
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static const struct clk_ops clk_sleeping_gpio_gate_ops = {
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.prepare = clk_sleeping_gpio_gate_prepare,
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.unprepare = clk_sleeping_gpio_gate_unprepare,
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.is_prepared = clk_sleeping_gpio_gate_is_prepared,
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};
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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_cansleep(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_cansleep(clk->gpiod, index);
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return 0;
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}
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static 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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static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents,
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struct gpio_desc *gpiod,
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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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int err;
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const struct clk_parent_data gpio_parent_data[] = {
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{ .index = 0 },
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{ .index = 1 },
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};
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clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
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if (!clk_gpio)
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return ERR_PTR(-ENOMEM);
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init.name = dev->of_node->name;
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init.ops = clk_gpio_ops;
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init.parent_data = gpio_parent_data;
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init.num_parents = num_parents;
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init.flags = CLK_SET_RATE_PARENT;
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clk_gpio->gpiod = gpiod;
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clk_gpio->hw.init = &init;
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hw = &clk_gpio->hw;
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err = devm_clk_hw_register(dev, hw);
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if (err)
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return ERR_PTR(err);
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return hw;
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}
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static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev,
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int num_parents,
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struct gpio_desc *gpiod)
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{
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const struct clk_ops *ops;
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if (gpiod_cansleep(gpiod))
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ops = &clk_sleeping_gpio_gate_ops;
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else
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ops = &clk_gpio_gate_ops;
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return clk_register_gpio(dev, num_parents, gpiod, ops);
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}
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static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev,
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struct gpio_desc *gpiod)
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{
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return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops);
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}
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static int gpio_clk_driver_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct device_node *node = dev->of_node;
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const char *gpio_name;
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unsigned int num_parents;
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struct gpio_desc *gpiod;
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struct clk_hw *hw;
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bool is_mux;
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int ret;
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is_mux = of_device_is_compatible(node, "gpio-mux-clock");
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num_parents = of_clk_get_parent_count(node);
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if (is_mux && num_parents != 2) {
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dev_err(dev, "mux-clock must have 2 parents\n");
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return -EINVAL;
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}
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gpio_name = is_mux ? "select" : "enable";
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gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW);
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if (IS_ERR(gpiod)) {
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ret = PTR_ERR(gpiod);
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if (ret == -EPROBE_DEFER)
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pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
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node, __func__);
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else
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pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n",
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node, __func__,
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gpio_name);
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return ret;
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}
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if (is_mux)
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hw = clk_hw_register_gpio_mux(dev, gpiod);
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else
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hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod);
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if (IS_ERR(hw))
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return PTR_ERR(hw);
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return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
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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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