aboutsummaryrefslogtreecommitdiff
path: root/drivers/clk/clk-gpio.c
blob: 38755a241ab76e017c63b178e3f1124ff5b4c900 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com
 *
 * Authors:
 *    Jyri Sarha <jsarha@ti.com>
 *    Sergej Sawazki <ce3a@gmx.de>
 *
 * Gpio controlled clock implementation
 */

#include <linux/clk-provider.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/gpio/consumer.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/of_device.h>

/**
 * DOC: basic gpio gated clock which can be enabled and disabled
 *      with gpio output
 * Traits of this clock:
 * prepare - clk_(un)prepare only ensures parent is (un)prepared
 * enable - clk_enable and clk_disable are functional & control gpio
 * rate - inherits rate from parent.  No clk_set_rate support
 * parent - fixed parent.  No clk_set_parent support
 */

/**
 * struct clk_gpio - gpio gated clock
 *
 * @hw:		handle between common and hardware-specific interfaces
 * @gpiod:	gpio descriptor
 *
 * Clock with a gpio control for enabling and disabling the parent clock
 * or switching between two parents by asserting or deasserting the gpio.
 *
 * Implements .enable, .disable and .is_enabled or
 * .get_parent, .set_parent and .determine_rate depending on which clk_ops
 * is used.
 */
struct clk_gpio {
	struct clk_hw	hw;
	struct gpio_desc *gpiod;
};

#define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)

static int clk_gpio_gate_enable(struct clk_hw *hw)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value(clk->gpiod, 1);

	return 0;
}

static void clk_gpio_gate_disable(struct clk_hw *hw)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value(clk->gpiod, 0);
}

static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	return gpiod_get_value(clk->gpiod);
}

static const struct clk_ops clk_gpio_gate_ops = {
	.enable = clk_gpio_gate_enable,
	.disable = clk_gpio_gate_disable,
	.is_enabled = clk_gpio_gate_is_enabled,
};

static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value_cansleep(clk->gpiod, 1);

	return 0;
}

static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value_cansleep(clk->gpiod, 0);
}

static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	return gpiod_get_value_cansleep(clk->gpiod);
}

static const struct clk_ops clk_sleeping_gpio_gate_ops = {
	.prepare = clk_sleeping_gpio_gate_prepare,
	.unprepare = clk_sleeping_gpio_gate_unprepare,
	.is_prepared = clk_sleeping_gpio_gate_is_prepared,
};

/**
 * DOC: basic clock multiplexer which can be controlled with a gpio output
 * Traits of this clock:
 * prepare - clk_prepare only ensures that parents are prepared
 * rate - rate is only affected by parent switching.  No clk_set_rate support
 * parent - parent is adjustable through clk_set_parent
 */

static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	return gpiod_get_value_cansleep(clk->gpiod);
}

static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
{
	struct clk_gpio *clk = to_clk_gpio(hw);

	gpiod_set_value_cansleep(clk->gpiod, index);

	return 0;
}

static const struct clk_ops clk_gpio_mux_ops = {
	.get_parent = clk_gpio_mux_get_parent,
	.set_parent = clk_gpio_mux_set_parent,
	.determine_rate = __clk_mux_determine_rate,
};

static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents,
					struct gpio_desc *gpiod,
					const struct clk_ops *clk_gpio_ops)
{
	struct clk_gpio *clk_gpio;
	struct clk_hw *hw;
	struct clk_init_data init = {};
	int err;
	const struct clk_parent_data gpio_parent_data[] = {
		{ .index = 0 },
		{ .index = 1 },
	};

	clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio),	GFP_KERNEL);
	if (!clk_gpio)
		return ERR_PTR(-ENOMEM);

	init.name = dev->of_node->name;
	init.ops = clk_gpio_ops;
	init.parent_data = gpio_parent_data;
	init.num_parents = num_parents;
	init.flags = CLK_SET_RATE_PARENT;

	clk_gpio->gpiod = gpiod;
	clk_gpio->hw.init = &init;

	hw = &clk_gpio->hw;
	err = devm_clk_hw_register(dev, hw);
	if (err)
		return ERR_PTR(err);

	return hw;
}

static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev,
						int num_parents,
						struct gpio_desc *gpiod)
{
	const struct clk_ops *ops;

	if (gpiod_cansleep(gpiod))
		ops = &clk_sleeping_gpio_gate_ops;
	else
		ops = &clk_gpio_gate_ops;

	return clk_register_gpio(dev, num_parents, gpiod, ops);
}

static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev,
					       struct gpio_desc *gpiod)
{
	return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops);
}

static int gpio_clk_driver_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *node = dev->of_node;
	const char *gpio_name;
	unsigned int num_parents;
	struct gpio_desc *gpiod;
	struct clk_hw *hw;
	bool is_mux;
	int ret;

	is_mux = of_device_is_compatible(node, "gpio-mux-clock");

	num_parents = of_clk_get_parent_count(node);
	if (is_mux && num_parents != 2) {
		dev_err(dev, "mux-clock must have 2 parents\n");
		return -EINVAL;
	}

	gpio_name = is_mux ? "select" : "enable";
	gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW);
	if (IS_ERR(gpiod)) {
		ret = PTR_ERR(gpiod);
		if (ret == -EPROBE_DEFER)
			pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
					node, __func__);
		else
			pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n",
					node, __func__,
					gpio_name);
		return ret;
	}

	if (is_mux)
		hw = clk_hw_register_gpio_mux(dev, gpiod);
	else
		hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod);
	if (IS_ERR(hw))
		return PTR_ERR(hw);

	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
}

static const struct of_device_id gpio_clk_match_table[] = {
	{ .compatible = "gpio-mux-clock" },
	{ .compatible = "gpio-gate-clock" },
	{ }
};

static struct platform_driver gpio_clk_driver = {
	.probe		= gpio_clk_driver_probe,
	.driver		= {
		.name	= "gpio-clk",
		.of_match_table = gpio_clk_match_table,
	},
};
builtin_platform_driver(gpio_clk_driver);