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
clk_gpio_gate_enable(struct clk_hw * hw)33 static 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
clk_gpio_gate_disable(struct clk_hw * hw)42 static 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
clk_gpio_gate_is_enabled(struct clk_hw * hw)49 static 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
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,
60 };
61 EXPORT_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 */
clk_register_gpio_gate(struct device * dev,const char * name,const char * parent_name,unsigned gpio,bool active_low,unsigned long flags)72 struct 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
126 clk_register_gpio_gate_err:
127 if (!dev)
128 gpio_free(gpio);
129
130 return clk;
131 }
132 EXPORT_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
140 struct clk_gpio_gate_delayed_register_data {
141 struct device_node *node;
142 struct mutex lock;
143 struct clk *clk;
144 };
145
of_clk_gpio_gate_delayed_register_get(struct of_phandle_args * clkspec,void * _data)146 static 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 */
of_gpio_gate_clk_setup(struct device_node * node)192 void __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 }
206 EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup);
207 CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup);
208 #endif
209