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c873d14d JS |
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/of_gpio.h> | |
17 | #include <linux/err.h> | |
18 | #include <linux/device.h> | |
19 | ||
20 | /** | |
21 | * DOC: basic gpio gated clock which can be enabled and disabled | |
22 | * with gpio output | |
23 | * Traits of this clock: | |
24 | * prepare - clk_(un)prepare only ensures parent is (un)prepared | |
25 | * enable - clk_enable and clk_disable are functional & control gpio | |
26 | * rate - inherits rate from parent. No clk_set_rate support | |
27 | * parent - fixed parent. No clk_set_parent support | |
28 | */ | |
29 | ||
30 | #define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw) | |
31 | ||
32 | static int clk_gpio_gate_enable(struct clk_hw *hw) | |
33 | { | |
34 | struct clk_gpio *clk = to_clk_gpio(hw); | |
35 | ||
36 | gpiod_set_value(clk->gpiod, 1); | |
37 | ||
38 | return 0; | |
39 | } | |
40 | ||
41 | static void clk_gpio_gate_disable(struct clk_hw *hw) | |
42 | { | |
43 | struct clk_gpio *clk = to_clk_gpio(hw); | |
44 | ||
45 | gpiod_set_value(clk->gpiod, 0); | |
46 | } | |
47 | ||
48 | static int clk_gpio_gate_is_enabled(struct clk_hw *hw) | |
49 | { | |
50 | struct clk_gpio *clk = to_clk_gpio(hw); | |
51 | ||
52 | return gpiod_get_value(clk->gpiod); | |
53 | } | |
54 | ||
55 | const struct clk_ops clk_gpio_gate_ops = { | |
56 | .enable = clk_gpio_gate_enable, | |
57 | .disable = clk_gpio_gate_disable, | |
58 | .is_enabled = clk_gpio_gate_is_enabled, | |
59 | }; | |
60 | EXPORT_SYMBOL_GPL(clk_gpio_gate_ops); | |
61 | ||
62 | /** | |
63 | * clk_register_gpio - register a gpip clock with the clock framework | |
64 | * @dev: device that is registering this clock | |
65 | * @name: name of this clock | |
66 | * @parent_name: name of this clock's parent | |
67 | * @gpiod: gpio descriptor to gate this clock | |
68 | */ | |
69 | struct clk *clk_register_gpio_gate(struct device *dev, const char *name, | |
70 | const char *parent_name, struct gpio_desc *gpiod, | |
71 | unsigned long flags) | |
72 | { | |
73 | struct clk_gpio *clk_gpio = NULL; | |
74 | struct clk *clk = ERR_PTR(-EINVAL); | |
75 | struct clk_init_data init = { NULL }; | |
76 | unsigned long gpio_flags; | |
77 | int err; | |
78 | ||
79 | if (gpiod_is_active_low(gpiod)) | |
80 | gpio_flags = GPIOF_OUT_INIT_HIGH; | |
81 | else | |
82 | gpio_flags = GPIOF_OUT_INIT_LOW; | |
83 | ||
84 | if (dev) | |
85 | err = devm_gpio_request_one(dev, desc_to_gpio(gpiod), | |
86 | gpio_flags, name); | |
87 | else | |
88 | err = gpio_request_one(desc_to_gpio(gpiod), gpio_flags, name); | |
89 | ||
90 | if (err) { | |
91 | pr_err("%s: %s: Error requesting clock control gpio %u\n", | |
92 | __func__, name, desc_to_gpio(gpiod)); | |
93 | return ERR_PTR(err); | |
94 | } | |
95 | ||
96 | if (dev) | |
97 | clk_gpio = devm_kzalloc(dev, sizeof(struct clk_gpio), | |
98 | GFP_KERNEL); | |
99 | else | |
100 | clk_gpio = kzalloc(sizeof(struct clk_gpio), GFP_KERNEL); | |
101 | ||
102 | if (!clk_gpio) { | |
103 | clk = ERR_PTR(-ENOMEM); | |
104 | goto clk_register_gpio_gate_err; | |
105 | } | |
106 | ||
107 | init.name = name; | |
108 | init.ops = &clk_gpio_gate_ops; | |
109 | init.flags = flags | CLK_IS_BASIC; | |
110 | init.parent_names = (parent_name ? &parent_name : NULL); | |
111 | init.num_parents = (parent_name ? 1 : 0); | |
112 | ||
113 | clk_gpio->gpiod = gpiod; | |
114 | clk_gpio->hw.init = &init; | |
115 | ||
116 | clk = clk_register(dev, &clk_gpio->hw); | |
117 | ||
118 | if (!IS_ERR(clk)) | |
119 | return clk; | |
120 | ||
121 | if (!dev) | |
122 | kfree(clk_gpio); | |
123 | ||
124 | clk_register_gpio_gate_err: | |
125 | gpiod_put(gpiod); | |
126 | ||
127 | return clk; | |
128 | } | |
129 | EXPORT_SYMBOL_GPL(clk_register_gpio_gate); | |
130 | ||
131 | #ifdef CONFIG_OF | |
132 | /** | |
133 | * The clk_register_gpio_gate has to be delayed, because the EPROBE_DEFER | |
134 | * can not be handled properly at of_clk_init() call time. | |
135 | */ | |
136 | ||
137 | struct clk_gpio_gate_delayed_register_data { | |
138 | struct device_node *node; | |
139 | struct mutex lock; | |
140 | struct clk *clk; | |
141 | }; | |
142 | ||
143 | static struct clk *of_clk_gpio_gate_delayed_register_get( | |
144 | struct of_phandle_args *clkspec, | |
145 | void *_data) | |
146 | { | |
147 | struct clk_gpio_gate_delayed_register_data *data = _data; | |
148 | struct clk *clk; | |
149 | const char *clk_name = data->node->name; | |
150 | const char *parent_name; | |
151 | struct gpio_desc *gpiod; | |
152 | int gpio; | |
153 | ||
154 | mutex_lock(&data->lock); | |
155 | ||
156 | if (data->clk) { | |
157 | mutex_unlock(&data->lock); | |
158 | return data->clk; | |
159 | } | |
160 | ||
161 | gpio = of_get_named_gpio_flags(data->node, "enable-gpios", 0, NULL); | |
162 | if (gpio < 0) { | |
163 | mutex_unlock(&data->lock); | |
164 | if (gpio != -EPROBE_DEFER) | |
165 | pr_err("%s: %s: Can't get 'enable-gpios' DT property\n", | |
166 | __func__, clk_name); | |
167 | return ERR_PTR(gpio); | |
168 | } | |
169 | gpiod = gpio_to_desc(gpio); | |
170 | ||
171 | parent_name = of_clk_get_parent_name(data->node, 0); | |
172 | ||
173 | clk = clk_register_gpio_gate(NULL, clk_name, parent_name, gpiod, 0); | |
174 | if (IS_ERR(clk)) { | |
175 | mutex_unlock(&data->lock); | |
176 | return clk; | |
177 | } | |
178 | ||
179 | data->clk = clk; | |
180 | mutex_unlock(&data->lock); | |
181 | ||
182 | return clk; | |
183 | } | |
184 | ||
185 | /** | |
186 | * of_gpio_gate_clk_setup() - Setup function for gpio controlled clock | |
187 | */ | |
188 | void __init of_gpio_gate_clk_setup(struct device_node *node) | |
189 | { | |
190 | struct clk_gpio_gate_delayed_register_data *data; | |
191 | ||
192 | data = kzalloc(sizeof(struct clk_gpio_gate_delayed_register_data), | |
193 | GFP_KERNEL); | |
194 | if (!data) | |
195 | return; | |
196 | ||
197 | data->node = node; | |
198 | mutex_init(&data->lock); | |
199 | ||
200 | of_clk_add_provider(node, of_clk_gpio_gate_delayed_register_get, data); | |
201 | } | |
202 | EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup); | |
203 | CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup); | |
204 | #endif |