summaryrefslogtreecommitdiff
path: root/drivers/input/misc/rotary_encoder.c
blob: e94cab8133becb9b5970789a1658cb38c59ca5a2 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * rotary_encoder.c
 *
 * (c) 2009 Daniel Mack <daniel@caiaq.de>
 * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
 *
 * state machine code inspired by code from Tim Ruetz
 *
 * A generic driver for rotary encoders connected to GPIO lines.
 * See file:Documentation/input/devices/rotary-encoder.rst for more information
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/property.h>

#define DRV_NAME "rotary-encoder"

enum rotary_encoder_encoding {
	ROTENC_GRAY,
	ROTENC_BINARY,
};

struct rotary_encoder {
	struct input_dev *input;

	struct mutex access_mutex;

	u32 steps;
	u32 axis;
	bool relative_axis;
	bool rollover;
	enum rotary_encoder_encoding encoding;

	unsigned int pos;

	struct gpio_descs *gpios;

	unsigned int *irq;

	bool armed;
	signed char dir;	/* 1 - clockwise, -1 - CCW */

	unsigned int last_stable;
};

static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
{
	int i;
	unsigned int ret = 0;

	for (i = 0; i < encoder->gpios->ndescs; ++i) {
		int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);

		/* convert from gray encoding to normal */
		if (encoder->encoding == ROTENC_GRAY && ret & 1)
			val = !val;

		ret = ret << 1 | val;
	}

	return ret & 3;
}

static void rotary_encoder_report_event(struct rotary_encoder *encoder)
{
	if (encoder->relative_axis) {
		input_report_rel(encoder->input,
				 encoder->axis, encoder->dir);
	} else {
		unsigned int pos = encoder->pos;

		if (encoder->dir < 0) {
			/* turning counter-clockwise */
			if (encoder->rollover)
				pos += encoder->steps;
			if (pos)
				pos--;
		} else {
			/* turning clockwise */
			if (encoder->rollover || pos < encoder->steps)
				pos++;
		}

		if (encoder->rollover)
			pos %= encoder->steps;

		encoder->pos = pos;
		input_report_abs(encoder->input, encoder->axis, encoder->pos);
	}

	input_sync(encoder->input);
}

static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
{
	struct rotary_encoder *encoder = dev_id;
	unsigned int state;

	mutex_lock(&encoder->access_mutex);

	state = rotary_encoder_get_state(encoder);

	switch (state) {
	case 0x0:
		if (encoder->armed) {
			rotary_encoder_report_event(encoder);
			encoder->armed = false;
		}
		break;

	case 0x1:
	case 0x3:
		if (encoder->armed)
			encoder->dir = 2 - state;
		break;

	case 0x2:
		encoder->armed = true;
		break;
	}

	mutex_unlock(&encoder->access_mutex);

	return IRQ_HANDLED;
}

static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
{
	struct rotary_encoder *encoder = dev_id;
	unsigned int state;

	mutex_lock(&encoder->access_mutex);

	state = rotary_encoder_get_state(encoder);

	if (state & 1) {
		encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
	} else {
		if (state != encoder->last_stable) {
			rotary_encoder_report_event(encoder);
			encoder->last_stable = state;
		}
	}

	mutex_unlock(&encoder->access_mutex);

	return IRQ_HANDLED;
}

static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
{
	struct rotary_encoder *encoder = dev_id;
	unsigned int state;

	mutex_lock(&encoder->access_mutex);

	state = rotary_encoder_get_state(encoder);

	if ((encoder->last_stable + 1) % 4 == state)
		encoder->dir = 1;
	else if (encoder->last_stable == (state + 1) % 4)
		encoder->dir = -1;
	else
		goto out;

	rotary_encoder_report_event(encoder);

out:
	encoder->last_stable = state;
	mutex_unlock(&encoder->access_mutex);

	return IRQ_HANDLED;
}

static int rotary_encoder_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct rotary_encoder *encoder;
	struct input_dev *input;
	irq_handler_t handler;
	u32 steps_per_period;
	unsigned int i;
	int err;

	encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
	if (!encoder)
		return -ENOMEM;

	mutex_init(&encoder->access_mutex);

	device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);

	err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
				       &steps_per_period);
	if (err) {
		/*
		 * The 'half-period' property has been deprecated, you must
		 * use 'steps-per-period' and set an appropriate value, but
		 * we still need to parse it to maintain compatibility. If
		 * neither property is present we fall back to the one step
		 * per period behavior.
		 */
		steps_per_period = device_property_read_bool(dev,
					"rotary-encoder,half-period") ? 2 : 1;
	}

	encoder->rollover =
		device_property_read_bool(dev, "rotary-encoder,rollover");

	if (!device_property_present(dev, "rotary-encoder,encoding") ||
	    !device_property_match_string(dev, "rotary-encoder,encoding",
					  "gray")) {
		dev_info(dev, "gray");
		encoder->encoding = ROTENC_GRAY;
	} else if (!device_property_match_string(dev, "rotary-encoder,encoding",
						 "binary")) {
		dev_info(dev, "binary");
		encoder->encoding = ROTENC_BINARY;
	} else {
		dev_err(dev, "unknown encoding setting\n");
		return -EINVAL;
	}

	device_property_read_u32(dev, "linux,axis", &encoder->axis);
	encoder->relative_axis =
		device_property_read_bool(dev, "rotary-encoder,relative-axis");

	encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
	if (IS_ERR(encoder->gpios))
		return dev_err_probe(dev, PTR_ERR(encoder->gpios), "unable to get gpios\n");
	if (encoder->gpios->ndescs < 2) {
		dev_err(dev, "not enough gpios found\n");
		return -EINVAL;
	}

	input = devm_input_allocate_device(dev);
	if (!input)
		return -ENOMEM;

	encoder->input = input;

	input->name = pdev->name;
	input->id.bustype = BUS_HOST;

	if (encoder->relative_axis)
		input_set_capability(input, EV_REL, encoder->axis);
	else
		input_set_abs_params(input,
				     encoder->axis, 0, encoder->steps, 0, 1);

	switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
	case 4:
		handler = &rotary_encoder_quarter_period_irq;
		encoder->last_stable = rotary_encoder_get_state(encoder);
		break;
	case 2:
		handler = &rotary_encoder_half_period_irq;
		encoder->last_stable = rotary_encoder_get_state(encoder);
		break;
	case 1:
		handler = &rotary_encoder_irq;
		break;
	default:
		dev_err(dev, "'%d' is not a valid steps-per-period value\n",
			steps_per_period);
		return -EINVAL;
	}

	encoder->irq =
		devm_kcalloc(dev,
			     encoder->gpios->ndescs, sizeof(*encoder->irq),
			     GFP_KERNEL);
	if (!encoder->irq)
		return -ENOMEM;

	for (i = 0; i < encoder->gpios->ndescs; ++i) {
		encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);

		err = devm_request_threaded_irq(dev, encoder->irq[i],
				NULL, handler,
				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
				IRQF_ONESHOT,
				DRV_NAME, encoder);
		if (err) {
			dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
				encoder->irq[i], i);
			return err;
		}
	}

	err = input_register_device(input);
	if (err) {
		dev_err(dev, "failed to register input device\n");
		return err;
	}

	device_init_wakeup(dev,
			   device_property_read_bool(dev, "wakeup-source"));

	platform_set_drvdata(pdev, encoder);

	return 0;
}

static int rotary_encoder_suspend(struct device *dev)
{
	struct rotary_encoder *encoder = dev_get_drvdata(dev);
	unsigned int i;

	if (device_may_wakeup(dev)) {
		for (i = 0; i < encoder->gpios->ndescs; ++i)
			enable_irq_wake(encoder->irq[i]);
	}

	return 0;
}

static int rotary_encoder_resume(struct device *dev)
{
	struct rotary_encoder *encoder = dev_get_drvdata(dev);
	unsigned int i;

	if (device_may_wakeup(dev)) {
		for (i = 0; i < encoder->gpios->ndescs; ++i)
			disable_irq_wake(encoder->irq[i]);
	}

	return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
				rotary_encoder_suspend, rotary_encoder_resume);

#ifdef CONFIG_OF
static const struct of_device_id rotary_encoder_of_match[] = {
	{ .compatible = "rotary-encoder", },
	{ },
};
MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
#endif

static struct platform_driver rotary_encoder_driver = {
	.probe		= rotary_encoder_probe,
	.driver		= {
		.name	= DRV_NAME,
		.pm	= pm_sleep_ptr(&rotary_encoder_pm_ops),
		.of_match_table = of_match_ptr(rotary_encoder_of_match),
	}
};
module_platform_driver(rotary_encoder_driver);

MODULE_ALIAS("platform:" DRV_NAME);
MODULE_DESCRIPTION("GPIO rotary encoder driver");
MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
MODULE_LICENSE("GPL v2");