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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com4 *5 * Authors:6 * Jyri Sarha <jsarha@ti.com>7 * Sergej Sawazki <ce3a@gmx.de>8 *9 * Gpio controlled clock implementation10 */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/of.h>19#include <linux/platform_device.h>20 21/**22 * DOC: basic gpio gated clock which can be enabled and disabled23 * with gpio output24 * Traits of this clock:25 * prepare - clk_(un)prepare only ensures parent is (un)prepared26 * enable - clk_enable and clk_disable are functional & control gpio27 * rate - inherits rate from parent. No clk_set_rate support28 * parent - fixed parent. No clk_set_parent support29 */30 31/**32 * struct clk_gpio - gpio gated clock33 *34 * @hw: handle between common and hardware-specific interfaces35 * @gpiod: gpio descriptor36 *37 * Clock with a gpio control for enabling and disabling the parent clock38 * or switching between two parents by asserting or deasserting the gpio.39 *40 * Implements .enable, .disable and .is_enabled or41 * .get_parent, .set_parent and .determine_rate depending on which clk_ops42 * 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 output111 * Traits of this clock:112 * prepare - clk_prepare only ensures that parents are prepared113 * rate - rate is only affected by parent switching. No clk_set_rate support114 * parent - parent is adjustable through clk_set_parent115 */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 else182 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 else220 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 else229 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