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1/*
2 * rotary_encoder.c
3 *
4 * (c) 2009 Daniel Mack <daniel@caiaq.de>
5 * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
6 *
7 * state machine code inspired by code from Tim Ruetz
8 *
9 * A generic driver for rotary encoders connected to GPIO lines.
10 * See file:Documentation/input/rotary-encoder.txt for more information
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/interrupt.h>
20#include <linux/input.h>
21#include <linux/device.h>
22#include <linux/platform_device.h>
23#include <linux/gpio/consumer.h>
24#include <linux/slab.h>
25#include <linux/of.h>
26#include <linux/pm.h>
27#include <linux/property.h>
28
29#define DRV_NAME "rotary-encoder"
30
31struct rotary_encoder {
32 struct input_dev *input;
33
34 struct mutex access_mutex;
35
36 u32 steps;
37 u32 axis;
38 bool relative_axis;
39 bool rollover;
40
41 unsigned int pos;
42
43 struct gpio_descs *gpios;
44
45 unsigned int *irq;
46
47 bool armed;
48 signed char dir; /* 1 - clockwise, -1 - CCW */
49
50 unsigned last_stable;
51};
52
53static unsigned rotary_encoder_get_state(struct rotary_encoder *encoder)
54{
55 int i;
56 unsigned ret = 0;
57
58 for (i = 0; i < encoder->gpios->ndescs; ++i) {
59 int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);
60 /* convert from gray encoding to normal */
61 if (ret & 1)
62 val = !val;
63
64 ret = ret << 1 | val;
65 }
66
67 return ret & 3;
68}
69
70static void rotary_encoder_report_event(struct rotary_encoder *encoder)
71{
72 if (encoder->relative_axis) {
73 input_report_rel(encoder->input,
74 encoder->axis, encoder->dir);
75 } else {
76 unsigned int pos = encoder->pos;
77
78 if (encoder->dir < 0) {
79 /* turning counter-clockwise */
80 if (encoder->rollover)
81 pos += encoder->steps;
82 if (pos)
83 pos--;
84 } else {
85 /* turning clockwise */
86 if (encoder->rollover || pos < encoder->steps)
87 pos++;
88 }
89
90 if (encoder->rollover)
91 pos %= encoder->steps;
92
93 encoder->pos = pos;
94 input_report_abs(encoder->input, encoder->axis, encoder->pos);
95 }
96
97 input_sync(encoder->input);
98}
99
100static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
101{
102 struct rotary_encoder *encoder = dev_id;
103 unsigned state;
104
105 mutex_lock(&encoder->access_mutex);
106
107 state = rotary_encoder_get_state(encoder);
108
109 switch (state) {
110 case 0x0:
111 if (encoder->armed) {
112 rotary_encoder_report_event(encoder);
113 encoder->armed = false;
114 }
115 break;
116
117 case 0x1:
118 case 0x3:
119 if (encoder->armed)
120 encoder->dir = 2 - state;
121 break;
122
123 case 0x2:
124 encoder->armed = true;
125 break;
126 }
127
128 mutex_unlock(&encoder->access_mutex);
129
130 return IRQ_HANDLED;
131}
132
133static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
134{
135 struct rotary_encoder *encoder = dev_id;
136 unsigned int state;
137
138 mutex_lock(&encoder->access_mutex);
139
140 state = rotary_encoder_get_state(encoder);
141
142 if (state & 1) {
143 encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
144 } else {
145 if (state != encoder->last_stable) {
146 rotary_encoder_report_event(encoder);
147 encoder->last_stable = state;
148 }
149 }
150
151 mutex_unlock(&encoder->access_mutex);
152
153 return IRQ_HANDLED;
154}
155
156static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
157{
158 struct rotary_encoder *encoder = dev_id;
159 unsigned int state;
160
161 mutex_lock(&encoder->access_mutex);
162
163 state = rotary_encoder_get_state(encoder);
164
165 if ((encoder->last_stable + 1) % 4 == state)
166 encoder->dir = 1;
167 else if (encoder->last_stable == (state + 1) % 4)
168 encoder->dir = -1;
169 else
170 goto out;
171
172 rotary_encoder_report_event(encoder);
173
174out:
175 encoder->last_stable = state;
176 mutex_unlock(&encoder->access_mutex);
177
178 return IRQ_HANDLED;
179}
180
181static int rotary_encoder_probe(struct platform_device *pdev)
182{
183 struct device *dev = &pdev->dev;
184 struct rotary_encoder *encoder;
185 struct input_dev *input;
186 irq_handler_t handler;
187 u32 steps_per_period;
188 unsigned int i;
189 int err;
190
191 encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
192 if (!encoder)
193 return -ENOMEM;
194
195 mutex_init(&encoder->access_mutex);
196
197 device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);
198
199 err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
200 &steps_per_period);
201 if (err) {
202 /*
203 * The 'half-period' property has been deprecated, you must
204 * use 'steps-per-period' and set an appropriate value, but
205 * we still need to parse it to maintain compatibility. If
206 * neither property is present we fall back to the one step
207 * per period behavior.
208 */
209 steps_per_period = device_property_read_bool(dev,
210 "rotary-encoder,half-period") ? 2 : 1;
211 }
212
213 encoder->rollover =
214 device_property_read_bool(dev, "rotary-encoder,rollover");
215
216 device_property_read_u32(dev, "linux,axis", &encoder->axis);
217 encoder->relative_axis =
218 device_property_read_bool(dev, "rotary-encoder,relative-axis");
219
220 encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
221 if (IS_ERR(encoder->gpios)) {
222 dev_err(dev, "unable to get gpios\n");
223 return PTR_ERR(encoder->gpios);
224 }
225 if (encoder->gpios->ndescs < 2) {
226 dev_err(dev, "not enough gpios found\n");
227 return -EINVAL;
228 }
229
230 input = devm_input_allocate_device(dev);
231 if (!input)
232 return -ENOMEM;
233
234 encoder->input = input;
235
236 input->name = pdev->name;
237 input->id.bustype = BUS_HOST;
238 input->dev.parent = dev;
239
240 if (encoder->relative_axis)
241 input_set_capability(input, EV_REL, encoder->axis);
242 else
243 input_set_abs_params(input,
244 encoder->axis, 0, encoder->steps, 0, 1);
245
246 switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
247 case 4:
248 handler = &rotary_encoder_quarter_period_irq;
249 encoder->last_stable = rotary_encoder_get_state(encoder);
250 break;
251 case 2:
252 handler = &rotary_encoder_half_period_irq;
253 encoder->last_stable = rotary_encoder_get_state(encoder);
254 break;
255 case 1:
256 handler = &rotary_encoder_irq;
257 break;
258 default:
259 dev_err(dev, "'%d' is not a valid steps-per-period value\n",
260 steps_per_period);
261 return -EINVAL;
262 }
263
264 encoder->irq =
265 devm_kzalloc(dev,
266 sizeof(*encoder->irq) * encoder->gpios->ndescs,
267 GFP_KERNEL);
268 if (!encoder->irq)
269 return -ENOMEM;
270
271 for (i = 0; i < encoder->gpios->ndescs; ++i) {
272 encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
273
274 err = devm_request_threaded_irq(dev, encoder->irq[i],
275 NULL, handler,
276 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
277 IRQF_ONESHOT,
278 DRV_NAME, encoder);
279 if (err) {
280 dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
281 encoder->irq[i], i);
282 return err;
283 }
284 }
285
286 err = input_register_device(input);
287 if (err) {
288 dev_err(dev, "failed to register input device\n");
289 return err;
290 }
291
292 device_init_wakeup(dev,
293 device_property_read_bool(dev, "wakeup-source"));
294
295 platform_set_drvdata(pdev, encoder);
296
297 return 0;
298}
299
300static int __maybe_unused rotary_encoder_suspend(struct device *dev)
301{
302 struct rotary_encoder *encoder = dev_get_drvdata(dev);
303 unsigned int i;
304
305 if (device_may_wakeup(dev)) {
306 for (i = 0; i < encoder->gpios->ndescs; ++i)
307 enable_irq_wake(encoder->irq[i]);
308 }
309
310 return 0;
311}
312
313static int __maybe_unused rotary_encoder_resume(struct device *dev)
314{
315 struct rotary_encoder *encoder = dev_get_drvdata(dev);
316 unsigned int i;
317
318 if (device_may_wakeup(dev)) {
319 for (i = 0; i < encoder->gpios->ndescs; ++i)
320 disable_irq_wake(encoder->irq[i]);
321 }
322
323 return 0;
324}
325
326static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
327 rotary_encoder_suspend, rotary_encoder_resume);
328
329#ifdef CONFIG_OF
330static const struct of_device_id rotary_encoder_of_match[] = {
331 { .compatible = "rotary-encoder", },
332 { },
333};
334MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
335#endif
336
337static struct platform_driver rotary_encoder_driver = {
338 .probe = rotary_encoder_probe,
339 .driver = {
340 .name = DRV_NAME,
341 .pm = &rotary_encoder_pm_ops,
342 .of_match_table = of_match_ptr(rotary_encoder_of_match),
343 }
344};
345module_platform_driver(rotary_encoder_driver);
346
347MODULE_ALIAS("platform:" DRV_NAME);
348MODULE_DESCRIPTION("GPIO rotary encoder driver");
349MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
350MODULE_LICENSE("GPL v2");
1/*
2 * rotary_encoder.c
3 *
4 * (c) 2009 Daniel Mack <daniel@caiaq.de>
5 * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
6 *
7 * state machine code inspired by code from Tim Ruetz
8 *
9 * A generic driver for rotary encoders connected to GPIO lines.
10 * See file:Documentation/input/rotary-encoder.txt for more information
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/interrupt.h>
20#include <linux/input.h>
21#include <linux/device.h>
22#include <linux/platform_device.h>
23#include <linux/gpio/consumer.h>
24#include <linux/slab.h>
25#include <linux/of.h>
26#include <linux/pm.h>
27#include <linux/property.h>
28
29#define DRV_NAME "rotary-encoder"
30
31enum rotary_encoder_encoding {
32 ROTENC_GRAY,
33 ROTENC_BINARY,
34};
35
36struct rotary_encoder {
37 struct input_dev *input;
38
39 struct mutex access_mutex;
40
41 u32 steps;
42 u32 axis;
43 bool relative_axis;
44 bool rollover;
45 enum rotary_encoder_encoding encoding;
46
47 unsigned int pos;
48
49 struct gpio_descs *gpios;
50
51 unsigned int *irq;
52
53 bool armed;
54 signed char dir; /* 1 - clockwise, -1 - CCW */
55
56 unsigned int last_stable;
57};
58
59static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
60{
61 int i;
62 unsigned int ret = 0;
63
64 for (i = 0; i < encoder->gpios->ndescs; ++i) {
65 int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);
66
67 /* convert from gray encoding to normal */
68 if (encoder->encoding == ROTENC_GRAY && ret & 1)
69 val = !val;
70
71 ret = ret << 1 | val;
72 }
73
74 return ret & 3;
75}
76
77static void rotary_encoder_report_event(struct rotary_encoder *encoder)
78{
79 if (encoder->relative_axis) {
80 input_report_rel(encoder->input,
81 encoder->axis, encoder->dir);
82 } else {
83 unsigned int pos = encoder->pos;
84
85 if (encoder->dir < 0) {
86 /* turning counter-clockwise */
87 if (encoder->rollover)
88 pos += encoder->steps;
89 if (pos)
90 pos--;
91 } else {
92 /* turning clockwise */
93 if (encoder->rollover || pos < encoder->steps)
94 pos++;
95 }
96
97 if (encoder->rollover)
98 pos %= encoder->steps;
99
100 encoder->pos = pos;
101 input_report_abs(encoder->input, encoder->axis, encoder->pos);
102 }
103
104 input_sync(encoder->input);
105}
106
107static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
108{
109 struct rotary_encoder *encoder = dev_id;
110 unsigned int state;
111
112 mutex_lock(&encoder->access_mutex);
113
114 state = rotary_encoder_get_state(encoder);
115
116 switch (state) {
117 case 0x0:
118 if (encoder->armed) {
119 rotary_encoder_report_event(encoder);
120 encoder->armed = false;
121 }
122 break;
123
124 case 0x1:
125 case 0x3:
126 if (encoder->armed)
127 encoder->dir = 2 - state;
128 break;
129
130 case 0x2:
131 encoder->armed = true;
132 break;
133 }
134
135 mutex_unlock(&encoder->access_mutex);
136
137 return IRQ_HANDLED;
138}
139
140static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
141{
142 struct rotary_encoder *encoder = dev_id;
143 unsigned int state;
144
145 mutex_lock(&encoder->access_mutex);
146
147 state = rotary_encoder_get_state(encoder);
148
149 if (state & 1) {
150 encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
151 } else {
152 if (state != encoder->last_stable) {
153 rotary_encoder_report_event(encoder);
154 encoder->last_stable = state;
155 }
156 }
157
158 mutex_unlock(&encoder->access_mutex);
159
160 return IRQ_HANDLED;
161}
162
163static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
164{
165 struct rotary_encoder *encoder = dev_id;
166 unsigned int state;
167
168 mutex_lock(&encoder->access_mutex);
169
170 state = rotary_encoder_get_state(encoder);
171
172 if ((encoder->last_stable + 1) % 4 == state)
173 encoder->dir = 1;
174 else if (encoder->last_stable == (state + 1) % 4)
175 encoder->dir = -1;
176 else
177 goto out;
178
179 rotary_encoder_report_event(encoder);
180
181out:
182 encoder->last_stable = state;
183 mutex_unlock(&encoder->access_mutex);
184
185 return IRQ_HANDLED;
186}
187
188static int rotary_encoder_probe(struct platform_device *pdev)
189{
190 struct device *dev = &pdev->dev;
191 struct rotary_encoder *encoder;
192 struct input_dev *input;
193 irq_handler_t handler;
194 u32 steps_per_period;
195 unsigned int i;
196 int err;
197
198 encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
199 if (!encoder)
200 return -ENOMEM;
201
202 mutex_init(&encoder->access_mutex);
203
204 device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);
205
206 err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
207 &steps_per_period);
208 if (err) {
209 /*
210 * The 'half-period' property has been deprecated, you must
211 * use 'steps-per-period' and set an appropriate value, but
212 * we still need to parse it to maintain compatibility. If
213 * neither property is present we fall back to the one step
214 * per period behavior.
215 */
216 steps_per_period = device_property_read_bool(dev,
217 "rotary-encoder,half-period") ? 2 : 1;
218 }
219
220 encoder->rollover =
221 device_property_read_bool(dev, "rotary-encoder,rollover");
222
223 if (!device_property_present(dev, "rotary-encoder,encoding") ||
224 !device_property_match_string(dev, "rotary-encoder,encoding",
225 "gray")) {
226 dev_info(dev, "gray");
227 encoder->encoding = ROTENC_GRAY;
228 } else if (!device_property_match_string(dev, "rotary-encoder,encoding",
229 "binary")) {
230 dev_info(dev, "binary");
231 encoder->encoding = ROTENC_BINARY;
232 } else {
233 dev_err(dev, "unknown encoding setting\n");
234 return -EINVAL;
235 }
236
237 device_property_read_u32(dev, "linux,axis", &encoder->axis);
238 encoder->relative_axis =
239 device_property_read_bool(dev, "rotary-encoder,relative-axis");
240
241 encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
242 if (IS_ERR(encoder->gpios)) {
243 dev_err(dev, "unable to get gpios\n");
244 return PTR_ERR(encoder->gpios);
245 }
246 if (encoder->gpios->ndescs < 2) {
247 dev_err(dev, "not enough gpios found\n");
248 return -EINVAL;
249 }
250
251 input = devm_input_allocate_device(dev);
252 if (!input)
253 return -ENOMEM;
254
255 encoder->input = input;
256
257 input->name = pdev->name;
258 input->id.bustype = BUS_HOST;
259 input->dev.parent = dev;
260
261 if (encoder->relative_axis)
262 input_set_capability(input, EV_REL, encoder->axis);
263 else
264 input_set_abs_params(input,
265 encoder->axis, 0, encoder->steps, 0, 1);
266
267 switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
268 case 4:
269 handler = &rotary_encoder_quarter_period_irq;
270 encoder->last_stable = rotary_encoder_get_state(encoder);
271 break;
272 case 2:
273 handler = &rotary_encoder_half_period_irq;
274 encoder->last_stable = rotary_encoder_get_state(encoder);
275 break;
276 case 1:
277 handler = &rotary_encoder_irq;
278 break;
279 default:
280 dev_err(dev, "'%d' is not a valid steps-per-period value\n",
281 steps_per_period);
282 return -EINVAL;
283 }
284
285 encoder->irq =
286 devm_kzalloc(dev,
287 sizeof(*encoder->irq) * encoder->gpios->ndescs,
288 GFP_KERNEL);
289 if (!encoder->irq)
290 return -ENOMEM;
291
292 for (i = 0; i < encoder->gpios->ndescs; ++i) {
293 encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
294
295 err = devm_request_threaded_irq(dev, encoder->irq[i],
296 NULL, handler,
297 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
298 IRQF_ONESHOT,
299 DRV_NAME, encoder);
300 if (err) {
301 dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
302 encoder->irq[i], i);
303 return err;
304 }
305 }
306
307 err = input_register_device(input);
308 if (err) {
309 dev_err(dev, "failed to register input device\n");
310 return err;
311 }
312
313 device_init_wakeup(dev,
314 device_property_read_bool(dev, "wakeup-source"));
315
316 platform_set_drvdata(pdev, encoder);
317
318 return 0;
319}
320
321static int __maybe_unused rotary_encoder_suspend(struct device *dev)
322{
323 struct rotary_encoder *encoder = dev_get_drvdata(dev);
324 unsigned int i;
325
326 if (device_may_wakeup(dev)) {
327 for (i = 0; i < encoder->gpios->ndescs; ++i)
328 enable_irq_wake(encoder->irq[i]);
329 }
330
331 return 0;
332}
333
334static int __maybe_unused rotary_encoder_resume(struct device *dev)
335{
336 struct rotary_encoder *encoder = dev_get_drvdata(dev);
337 unsigned int i;
338
339 if (device_may_wakeup(dev)) {
340 for (i = 0; i < encoder->gpios->ndescs; ++i)
341 disable_irq_wake(encoder->irq[i]);
342 }
343
344 return 0;
345}
346
347static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
348 rotary_encoder_suspend, rotary_encoder_resume);
349
350#ifdef CONFIG_OF
351static const struct of_device_id rotary_encoder_of_match[] = {
352 { .compatible = "rotary-encoder", },
353 { },
354};
355MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
356#endif
357
358static struct platform_driver rotary_encoder_driver = {
359 .probe = rotary_encoder_probe,
360 .driver = {
361 .name = DRV_NAME,
362 .pm = &rotary_encoder_pm_ops,
363 .of_match_table = of_match_ptr(rotary_encoder_of_match),
364 }
365};
366module_platform_driver(rotary_encoder_driver);
367
368MODULE_ALIAS("platform:" DRV_NAME);
369MODULE_DESCRIPTION("GPIO rotary encoder driver");
370MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
371MODULE_LICENSE("GPL v2");