1/* 2 * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com 3 * Author: Jyri Sarha <jsarha@ti.com> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 * 9 * Gpio gated clock implementation 10 */ 11 12#include <linux/clk-provider.h> 13#include <linux/module.h> 14#include <linux/slab.h> 15#include <linux/gpio.h> 16#include <linux/gpio/consumer.h> 17#include <linux/of_gpio.h> 18#include <linux/err.h> 19#include <linux/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#define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw) 32 33static int clk_gpio_gate_enable(struct clk_hw *hw) 34{ 35 struct clk_gpio *clk = to_clk_gpio(hw); 36 37 gpiod_set_value(clk->gpiod, 1); 38 39 return 0; 40} 41 42static void clk_gpio_gate_disable(struct clk_hw *hw) 43{ 44 struct clk_gpio *clk = to_clk_gpio(hw); 45 46 gpiod_set_value(clk->gpiod, 0); 47} 48 49static int clk_gpio_gate_is_enabled(struct clk_hw *hw) 50{ 51 struct clk_gpio *clk = to_clk_gpio(hw); 52 53 return gpiod_get_value(clk->gpiod); 54} 55 56const struct clk_ops clk_gpio_gate_ops = { 57 .enable = clk_gpio_gate_enable, 58 .disable = clk_gpio_gate_disable, 59 .is_enabled = clk_gpio_gate_is_enabled, 60}; 61EXPORT_SYMBOL_GPL(clk_gpio_gate_ops); 62 63/** 64 * clk_register_gpio - register a gpip clock with the clock framework 65 * @dev: device that is registering this clock 66 * @name: name of this clock 67 * @parent_name: name of this clock's parent 68 * @gpio: gpio number to gate this clock 69 * @active_low: true if gpio should be set to 0 to enable clock 70 * @flags: clock flags 71 */ 72struct clk *clk_register_gpio_gate(struct device *dev, const char *name, 73 const char *parent_name, unsigned gpio, bool active_low, 74 unsigned long flags) 75{ 76 struct clk_gpio *clk_gpio = NULL; 77 struct clk *clk = ERR_PTR(-EINVAL); 78 struct clk_init_data init = { NULL }; 79 unsigned long gpio_flags; 80 int err; 81 82 if (active_low) 83 gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH; 84 else 85 gpio_flags = GPIOF_OUT_INIT_LOW; 86 87 if (dev) 88 err = devm_gpio_request_one(dev, gpio, gpio_flags, name); 89 else 90 err = gpio_request_one(gpio, gpio_flags, name); 91 92 if (err) { 93 pr_err("%s: %s: Error requesting clock control gpio %u\n", 94 __func__, name, gpio); 95 return ERR_PTR(err); 96 } 97 98 if (dev) 99 clk_gpio = devm_kzalloc(dev, sizeof(struct clk_gpio), 100 GFP_KERNEL); 101 else 102 clk_gpio = kzalloc(sizeof(struct clk_gpio), GFP_KERNEL); 103 104 if (!clk_gpio) { 105 clk = ERR_PTR(-ENOMEM); 106 goto clk_register_gpio_gate_err; 107 } 108 109 init.name = name; 110 init.ops = &clk_gpio_gate_ops; 111 init.flags = flags | CLK_IS_BASIC; 112 init.parent_names = (parent_name ? &parent_name : NULL); 113 init.num_parents = (parent_name ? 1 : 0); 114 115 clk_gpio->gpiod = gpio_to_desc(gpio); 116 clk_gpio->hw.init = &init; 117 118 clk = clk_register(dev, &clk_gpio->hw); 119 120 if (!IS_ERR(clk)) 121 return clk; 122 123 if (!dev) 124 kfree(clk_gpio); 125 126clk_register_gpio_gate_err: 127 if (!dev) 128 gpio_free(gpio); 129 130 return clk; 131} 132EXPORT_SYMBOL_GPL(clk_register_gpio_gate); 133 134#ifdef CONFIG_OF 135/** 136 * The clk_register_gpio_gate has to be delayed, because the EPROBE_DEFER 137 * can not be handled properly at of_clk_init() call time. 138 */ 139 140struct clk_gpio_gate_delayed_register_data { 141 struct device_node *node; 142 struct mutex lock; 143 struct clk *clk; 144}; 145 146static struct clk *of_clk_gpio_gate_delayed_register_get( 147 struct of_phandle_args *clkspec, 148 void *_data) 149{ 150 struct clk_gpio_gate_delayed_register_data *data = _data; 151 struct clk *clk; 152 const char *clk_name = data->node->name; 153 const char *parent_name; 154 int gpio; 155 enum of_gpio_flags of_flags; 156 157 mutex_lock(&data->lock); 158 159 if (data->clk) { 160 mutex_unlock(&data->lock); 161 return data->clk; 162 } 163 164 gpio = of_get_named_gpio_flags(data->node, "enable-gpios", 0, 165 &of_flags); 166 if (gpio < 0) { 167 mutex_unlock(&data->lock); 168 if (gpio != -EPROBE_DEFER) 169 pr_err("%s: %s: Can't get 'enable-gpios' DT property\n", 170 __func__, clk_name); 171 return ERR_PTR(gpio); 172 } 173 174 parent_name = of_clk_get_parent_name(data->node, 0); 175 176 clk = clk_register_gpio_gate(NULL, clk_name, parent_name, gpio, 177 of_flags & OF_GPIO_ACTIVE_LOW, 0); 178 if (IS_ERR(clk)) { 179 mutex_unlock(&data->lock); 180 return clk; 181 } 182 183 data->clk = clk; 184 mutex_unlock(&data->lock); 185 186 return clk; 187} 188 189/** 190 * of_gpio_gate_clk_setup() - Setup function for gpio controlled clock 191 */ 192void __init of_gpio_gate_clk_setup(struct device_node *node) 193{ 194 struct clk_gpio_gate_delayed_register_data *data; 195 196 data = kzalloc(sizeof(struct clk_gpio_gate_delayed_register_data), 197 GFP_KERNEL); 198 if (!data) 199 return; 200 201 data->node = node; 202 mutex_init(&data->lock); 203 204 of_clk_add_provider(node, of_clk_gpio_gate_delayed_register_get, data); 205} 206EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup); 207CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup); 208#endif 209