summaryrefslogtreecommitdiff
path: root/drivers/clk/clk-gpio.c
blob: 9099c57e27156c77fea060a9d68a110ce6f24ada (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
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
// 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/of.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

/**
 * DOC: basic gpio gated clock which can be enabled and disabled
 *      with gpio output
 * Traits of this clock:
 * prepare - clk_(un)prepare are functional and control a gpio that can sleep
 * enable - clk_enable and clk_disable are functional & control
 *          non-sleeping 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;

	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))
		return dev_err_probe(dev, PTR_ERR(gpiod),
				     "Can't get '%s' named GPIO property\n", gpio_name);

	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);

/**
 * DOC: gated fixed clock, controlled with a gpio output and a regulator
 * Traits of this clock:
 * prepare - clk_prepare and clk_unprepare are function & control regulator
 *           optionally a gpio that can sleep
 * enable - clk_enable and clk_disable are functional & control gpio
 * rate - rate is fixed and set on clock registration
 * parent - fixed clock is a root clock and has no parent
 */

/**
 * struct clk_gated_fixed - Gateable fixed rate clock
 * @clk_gpio:	instance of clk_gpio for gate-gpio
 * @supply:	supply regulator
 * @rate:	fixed rate
 */
struct clk_gated_fixed {
	struct clk_gpio clk_gpio;
	struct regulator *supply;
	unsigned long rate;
};

#define to_clk_gated_fixed(_clk_gpio) container_of(_clk_gpio, struct clk_gated_fixed, clk_gpio)

static unsigned long clk_gated_fixed_recalc_rate(struct clk_hw *hw,
						 unsigned long parent_rate)
{
	return to_clk_gated_fixed(to_clk_gpio(hw))->rate;
}

static int clk_gated_fixed_prepare(struct clk_hw *hw)
{
	struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));

	if (!clk->supply)
		return 0;

	return regulator_enable(clk->supply);
}

static void clk_gated_fixed_unprepare(struct clk_hw *hw)
{
	struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));

	if (!clk->supply)
		return;

	regulator_disable(clk->supply);
}

static int clk_gated_fixed_is_prepared(struct clk_hw *hw)
{
	struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));

	if (!clk->supply)
		return true;

	return regulator_is_enabled(clk->supply);
}

/*
 * Fixed gated clock with non-sleeping gpio.
 *
 * Prepare operation turns on the supply regulator
 * and the enable operation switches the enable-gpio.
 */
static const struct clk_ops clk_gated_fixed_ops = {
	.prepare = clk_gated_fixed_prepare,
	.unprepare = clk_gated_fixed_unprepare,
	.is_prepared = clk_gated_fixed_is_prepared,
	.enable = clk_gpio_gate_enable,
	.disable = clk_gpio_gate_disable,
	.is_enabled = clk_gpio_gate_is_enabled,
	.recalc_rate = clk_gated_fixed_recalc_rate,
};

static int clk_sleeping_gated_fixed_prepare(struct clk_hw *hw)
{
	int ret;

	ret = clk_gated_fixed_prepare(hw);
	if (ret)
		return ret;

	ret = clk_sleeping_gpio_gate_prepare(hw);
	if (ret)
		clk_gated_fixed_unprepare(hw);

	return ret;
}

static void clk_sleeping_gated_fixed_unprepare(struct clk_hw *hw)
{
	clk_gated_fixed_unprepare(hw);
	clk_sleeping_gpio_gate_unprepare(hw);
}

/*
 * Fixed gated clock with non-sleeping gpio.
 *
 * Enabling the supply regulator and switching the enable-gpio happens
 * both in the prepare step.
 * is_prepared only needs to check the gpio state, as toggling the
 * gpio is the last step when preparing.
 */
static const struct clk_ops clk_sleeping_gated_fixed_ops = {
	.prepare = clk_sleeping_gated_fixed_prepare,
	.unprepare = clk_sleeping_gated_fixed_unprepare,
	.is_prepared = clk_sleeping_gpio_gate_is_prepared,
	.recalc_rate = clk_gated_fixed_recalc_rate,
};

static int clk_gated_fixed_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct clk_gated_fixed *clk;
	const struct clk_ops *ops;
	const char *clk_name;
	u32 rate;
	int ret;

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

	ret = device_property_read_u32(dev, "clock-frequency", &rate);
	if (ret)
		return dev_err_probe(dev, ret, "Failed to get clock-frequency\n");
	clk->rate = rate;

	ret = device_property_read_string(dev, "clock-output-names", &clk_name);
	if (ret)
		clk_name = fwnode_get_name(dev->fwnode);

	clk->supply = devm_regulator_get_optional(dev, "vdd");
	if (IS_ERR(clk->supply)) {
		if (PTR_ERR(clk->supply) != -ENODEV)
			return dev_err_probe(dev, PTR_ERR(clk->supply),
					     "Failed to get regulator\n");
		clk->supply = NULL;
	}

	clk->clk_gpio.gpiod = devm_gpiod_get_optional(dev, "enable",
						      GPIOD_OUT_LOW);
	if (IS_ERR(clk->clk_gpio.gpiod))
		return dev_err_probe(dev, PTR_ERR(clk->clk_gpio.gpiod),
				     "Failed to get gpio\n");

	if (gpiod_cansleep(clk->clk_gpio.gpiod))
		ops = &clk_sleeping_gated_fixed_ops;
	else
		ops = &clk_gated_fixed_ops;

	clk->clk_gpio.hw.init = CLK_HW_INIT_NO_PARENT(clk_name, ops, 0);

	/* register the clock */
	ret = devm_clk_hw_register(dev, &clk->clk_gpio.hw);
	if (ret)
		return dev_err_probe(dev, ret,
				     "Failed to register clock\n");

	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
					  &clk->clk_gpio.hw);
	if (ret)
		return dev_err_probe(dev, ret,
				     "Failed to register clock provider\n");

	return 0;
}

static const struct of_device_id gated_fixed_clk_match_table[] = {
	{ .compatible = "gated-fixed-clock" },
	{ /* sentinel */ }
};

static struct platform_driver gated_fixed_clk_driver = {
	.probe		= clk_gated_fixed_probe,
	.driver		= {
		.name	= "gated-fixed-clk",
		.of_match_table = gated_fixed_clk_match_table,
	},
};
builtin_platform_driver(gated_fixed_clk_driver);