2 * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
3 * Author: Jyri Sarha <jsarha@ti.com>
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.
9 * Gpio gated clock implementation
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>
22 * DOC: basic gpio gated clock which can be enabled and disabled
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
31 #define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)
33 static int clk_gpio_gate_enable(struct clk_hw *hw)
35 struct clk_gpio *clk = to_clk_gpio(hw);
37 gpiod_set_value(clk->gpiod, 1);
42 static void clk_gpio_gate_disable(struct clk_hw *hw)
44 struct clk_gpio *clk = to_clk_gpio(hw);
46 gpiod_set_value(clk->gpiod, 0);
49 static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
51 struct clk_gpio *clk = to_clk_gpio(hw);
53 return gpiod_get_value(clk->gpiod);
56 const 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,
61 EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);
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 * @gpiod: gpio descriptor to gate this clock
70 struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
71 const char *parent_name, struct gpio_desc *gpiod,
74 struct clk_gpio *clk_gpio = NULL;
75 struct clk *clk = ERR_PTR(-EINVAL);
76 struct clk_init_data init = { NULL };
77 unsigned long gpio_flags;
80 if (gpiod_is_active_low(gpiod))
81 gpio_flags = GPIOF_OUT_INIT_HIGH;
83 gpio_flags = GPIOF_OUT_INIT_LOW;
86 err = devm_gpio_request_one(dev, desc_to_gpio(gpiod),
89 err = gpio_request_one(desc_to_gpio(gpiod), gpio_flags, name);
92 pr_err("%s: %s: Error requesting clock control gpio %u\n",
93 __func__, name, desc_to_gpio(gpiod));
98 clk_gpio = devm_kzalloc(dev, sizeof(struct clk_gpio),
101 clk_gpio = kzalloc(sizeof(struct clk_gpio), GFP_KERNEL);
104 clk = ERR_PTR(-ENOMEM);
105 goto clk_register_gpio_gate_err;
109 init.ops = &clk_gpio_gate_ops;
110 init.flags = flags | CLK_IS_BASIC;
111 init.parent_names = (parent_name ? &parent_name : NULL);
112 init.num_parents = (parent_name ? 1 : 0);
114 clk_gpio->gpiod = gpiod;
115 clk_gpio->hw.init = &init;
117 clk = clk_register(dev, &clk_gpio->hw);
125 clk_register_gpio_gate_err:
130 EXPORT_SYMBOL_GPL(clk_register_gpio_gate);
134 * The clk_register_gpio_gate has to be delayed, because the EPROBE_DEFER
135 * can not be handled properly at of_clk_init() call time.
138 struct clk_gpio_gate_delayed_register_data {
139 struct device_node *node;
144 static struct clk *of_clk_gpio_gate_delayed_register_get(
145 struct of_phandle_args *clkspec,
148 struct clk_gpio_gate_delayed_register_data *data = _data;
150 const char *clk_name = data->node->name;
151 const char *parent_name;
152 struct gpio_desc *gpiod;
155 mutex_lock(&data->lock);
158 mutex_unlock(&data->lock);
162 gpio = of_get_named_gpio_flags(data->node, "enable-gpios", 0, NULL);
164 mutex_unlock(&data->lock);
165 if (gpio != -EPROBE_DEFER)
166 pr_err("%s: %s: Can't get 'enable-gpios' DT property\n",
168 return ERR_PTR(gpio);
170 gpiod = gpio_to_desc(gpio);
172 parent_name = of_clk_get_parent_name(data->node, 0);
174 clk = clk_register_gpio_gate(NULL, clk_name, parent_name, gpiod, 0);
176 mutex_unlock(&data->lock);
181 mutex_unlock(&data->lock);
187 * of_gpio_gate_clk_setup() - Setup function for gpio controlled clock
189 void __init of_gpio_gate_clk_setup(struct device_node *node)
191 struct clk_gpio_gate_delayed_register_data *data;
193 data = kzalloc(sizeof(struct clk_gpio_gate_delayed_register_data),
199 mutex_init(&data->lock);
201 of_clk_add_provider(node, of_clk_gpio_gate_delayed_register_get, data);
203 EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup);
204 CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup);