linux/drivers/clk/clk-gpio.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com
   4 *
   5 * Authors:
   6 *    Jyri Sarha <jsarha@ti.com>
   7 *    Sergej Sawazki <ce3a@gmx.de>
   8 *
   9 * Gpio controlled clock implementation
  10 */
  11
  12#include <linux/clk-provider.h>
  13#include <linux/export.h>
  14#include <linux/slab.h>
  15#include <linux/gpio/consumer.h>
  16#include <linux/err.h>
  17#include <linux/device.h>
  18#include <linux/platform_device.h>
  19#include <linux/of_device.h>
  20
  21/**
  22 * DOC: basic gpio gated clock which can be enabled and disabled
  23 *      with gpio output
  24 * Traits of this clock:
  25 * prepare - clk_(un)prepare only ensures parent is (un)prepared
  26 * enable - clk_enable and clk_disable are functional & control gpio
  27 * rate - inherits rate from parent.  No clk_set_rate support
  28 * parent - fixed parent.  No clk_set_parent support
  29 */
  30
  31/**
  32 * struct clk_gpio - gpio gated clock
  33 *
  34 * @hw:         handle between common and hardware-specific interfaces
  35 * @gpiod:      gpio descriptor
  36 *
  37 * Clock with a gpio control for enabling and disabling the parent clock
  38 * or switching between two parents by asserting or deasserting the gpio.
  39 *
  40 * Implements .enable, .disable and .is_enabled or
  41 * .get_parent, .set_parent and .determine_rate depending on which clk_ops
  42 * is used.
  43 */
  44struct clk_gpio {
  45        struct clk_hw   hw;
  46        struct gpio_desc *gpiod;
  47};
  48
  49#define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)
  50
  51static int clk_gpio_gate_enable(struct clk_hw *hw)
  52{
  53        struct clk_gpio *clk = to_clk_gpio(hw);
  54
  55        gpiod_set_value(clk->gpiod, 1);
  56
  57        return 0;
  58}
  59
  60static void clk_gpio_gate_disable(struct clk_hw *hw)
  61{
  62        struct clk_gpio *clk = to_clk_gpio(hw);
  63
  64        gpiod_set_value(clk->gpiod, 0);
  65}
  66
  67static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
  68{
  69        struct clk_gpio *clk = to_clk_gpio(hw);
  70
  71        return gpiod_get_value(clk->gpiod);
  72}
  73
  74static const struct clk_ops clk_gpio_gate_ops = {
  75        .enable = clk_gpio_gate_enable,
  76        .disable = clk_gpio_gate_disable,
  77        .is_enabled = clk_gpio_gate_is_enabled,
  78};
  79
  80static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
  81{
  82        struct clk_gpio *clk = to_clk_gpio(hw);
  83
  84        gpiod_set_value_cansleep(clk->gpiod, 1);
  85
  86        return 0;
  87}
  88
  89static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
  90{
  91        struct clk_gpio *clk = to_clk_gpio(hw);
  92
  93        gpiod_set_value_cansleep(clk->gpiod, 0);
  94}
  95
  96static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
  97{
  98        struct clk_gpio *clk = to_clk_gpio(hw);
  99
 100        return gpiod_get_value_cansleep(clk->gpiod);
 101}
 102
 103static const struct clk_ops clk_sleeping_gpio_gate_ops = {
 104        .prepare = clk_sleeping_gpio_gate_prepare,
 105        .unprepare = clk_sleeping_gpio_gate_unprepare,
 106        .is_prepared = clk_sleeping_gpio_gate_is_prepared,
 107};
 108
 109/**
 110 * DOC: basic clock multiplexer which can be controlled with a gpio output
 111 * Traits of this clock:
 112 * prepare - clk_prepare only ensures that parents are prepared
 113 * rate - rate is only affected by parent switching.  No clk_set_rate support
 114 * parent - parent is adjustable through clk_set_parent
 115 */
 116
 117static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
 118{
 119        struct clk_gpio *clk = to_clk_gpio(hw);
 120
 121        return gpiod_get_value_cansleep(clk->gpiod);
 122}
 123
 124static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
 125{
 126        struct clk_gpio *clk = to_clk_gpio(hw);
 127
 128        gpiod_set_value_cansleep(clk->gpiod, index);
 129
 130        return 0;
 131}
 132
 133static const struct clk_ops clk_gpio_mux_ops = {
 134        .get_parent = clk_gpio_mux_get_parent,
 135        .set_parent = clk_gpio_mux_set_parent,
 136        .determine_rate = __clk_mux_determine_rate,
 137};
 138
 139static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents,
 140                                        struct gpio_desc *gpiod,
 141                                        const struct clk_ops *clk_gpio_ops)
 142{
 143        struct clk_gpio *clk_gpio;
 144        struct clk_hw *hw;
 145        struct clk_init_data init = {};
 146        int err;
 147        const struct clk_parent_data gpio_parent_data[] = {
 148                { .index = 0 },
 149                { .index = 1 },
 150        };
 151
 152        clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
 153        if (!clk_gpio)
 154                return ERR_PTR(-ENOMEM);
 155
 156        init.name = dev->of_node->name;
 157        init.ops = clk_gpio_ops;
 158        init.parent_data = gpio_parent_data;
 159        init.num_parents = num_parents;
 160        init.flags = CLK_SET_RATE_PARENT;
 161
 162        clk_gpio->gpiod = gpiod;
 163        clk_gpio->hw.init = &init;
 164
 165        hw = &clk_gpio->hw;
 166        err = devm_clk_hw_register(dev, hw);
 167        if (err)
 168                return ERR_PTR(err);
 169
 170        return hw;
 171}
 172
 173static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev,
 174                                                int num_parents,
 175                                                struct gpio_desc *gpiod)
 176{
 177        const struct clk_ops *ops;
 178
 179        if (gpiod_cansleep(gpiod))
 180                ops = &clk_sleeping_gpio_gate_ops;
 181        else
 182                ops = &clk_gpio_gate_ops;
 183
 184        return clk_register_gpio(dev, num_parents, gpiod, ops);
 185}
 186
 187static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev,
 188                                               struct gpio_desc *gpiod)
 189{
 190        return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops);
 191}
 192
 193static int gpio_clk_driver_probe(struct platform_device *pdev)
 194{
 195        struct device *dev = &pdev->dev;
 196        struct device_node *node = dev->of_node;
 197        const char *gpio_name;
 198        unsigned int num_parents;
 199        struct gpio_desc *gpiod;
 200        struct clk_hw *hw;
 201        bool is_mux;
 202        int ret;
 203
 204        is_mux = of_device_is_compatible(node, "gpio-mux-clock");
 205
 206        num_parents = of_clk_get_parent_count(node);
 207        if (is_mux && num_parents != 2) {
 208                dev_err(dev, "mux-clock must have 2 parents\n");
 209                return -EINVAL;
 210        }
 211
 212        gpio_name = is_mux ? "select" : "enable";
 213        gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW);
 214        if (IS_ERR(gpiod)) {
 215                ret = PTR_ERR(gpiod);
 216                if (ret == -EPROBE_DEFER)
 217                        pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
 218                                        node, __func__);
 219                else
 220                        pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n",
 221                                        node, __func__,
 222                                        gpio_name);
 223                return ret;
 224        }
 225
 226        if (is_mux)
 227                hw = clk_hw_register_gpio_mux(dev, gpiod);
 228        else
 229                hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod);
 230        if (IS_ERR(hw))
 231                return PTR_ERR(hw);
 232
 233        return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
 234}
 235
 236static const struct of_device_id gpio_clk_match_table[] = {
 237        { .compatible = "gpio-mux-clock" },
 238        { .compatible = "gpio-gate-clock" },
 239        { }
 240};
 241
 242static struct platform_driver gpio_clk_driver = {
 243        .probe          = gpio_clk_driver_probe,
 244        .driver         = {
 245                .name   = "gpio-clk",
 246                .of_match_table = gpio_clk_match_table,
 247        },
 248};
 249builtin_platform_driver(gpio_clk_driver);
 250