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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/init.h>
20#include <linux/interrupt.h>
21#include <linux/input.h>
22#include <linux/device.h>
23#include <linux/platform_device.h>
24#include <linux/gpio.h>
25#include <linux/rotary_encoder.h>
26#include <linux/slab.h>
27
28#define DRV_NAME "rotary-encoder"
29
30struct rotary_encoder {
31 struct input_dev *input;
32 struct rotary_encoder_platform_data *pdata;
33
34 unsigned int axis;
35 unsigned int pos;
36
37 unsigned int irq_a;
38 unsigned int irq_b;
39
40 bool armed;
41 unsigned char dir; /* 0 - clockwise, 1 - CCW */
42
43 char last_stable;
44};
45
46static int rotary_encoder_get_state(struct rotary_encoder_platform_data *pdata)
47{
48 int a = !!gpio_get_value(pdata->gpio_a);
49 int b = !!gpio_get_value(pdata->gpio_b);
50
51 a ^= pdata->inverted_a;
52 b ^= pdata->inverted_b;
53
54 return ((a << 1) | b);
55}
56
57static void rotary_encoder_report_event(struct rotary_encoder *encoder)
58{
59 struct rotary_encoder_platform_data *pdata = encoder->pdata;
60
61 if (pdata->relative_axis) {
62 input_report_rel(encoder->input,
63 pdata->axis, encoder->dir ? -1 : 1);
64 } else {
65 unsigned int pos = encoder->pos;
66
67 if (encoder->dir) {
68 /* turning counter-clockwise */
69 if (pdata->rollover)
70 pos += pdata->steps;
71 if (pos)
72 pos--;
73 } else {
74 /* turning clockwise */
75 if (pdata->rollover || pos < pdata->steps)
76 pos++;
77 }
78
79 if (pdata->rollover)
80 pos %= pdata->steps;
81
82 encoder->pos = pos;
83 input_report_abs(encoder->input, pdata->axis, encoder->pos);
84 }
85
86 input_sync(encoder->input);
87}
88
89static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
90{
91 struct rotary_encoder *encoder = dev_id;
92 int state;
93
94 state = rotary_encoder_get_state(encoder->pdata);
95
96 switch (state) {
97 case 0x0:
98 if (encoder->armed) {
99 rotary_encoder_report_event(encoder);
100 encoder->armed = false;
101 }
102 break;
103
104 case 0x1:
105 case 0x2:
106 if (encoder->armed)
107 encoder->dir = state - 1;
108 break;
109
110 case 0x3:
111 encoder->armed = true;
112 break;
113 }
114
115 return IRQ_HANDLED;
116}
117
118static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
119{
120 struct rotary_encoder *encoder = dev_id;
121 int state;
122
123 state = rotary_encoder_get_state(encoder->pdata);
124
125 switch (state) {
126 case 0x00:
127 case 0x03:
128 if (state != encoder->last_stable) {
129 rotary_encoder_report_event(encoder);
130 encoder->last_stable = state;
131 }
132 break;
133
134 case 0x01:
135 case 0x02:
136 encoder->dir = (encoder->last_stable + state) & 0x01;
137 break;
138 }
139
140 return IRQ_HANDLED;
141}
142
143static int __devinit rotary_encoder_probe(struct platform_device *pdev)
144{
145 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
146 struct rotary_encoder *encoder;
147 struct input_dev *input;
148 irq_handler_t handler;
149 int err;
150
151 if (!pdata) {
152 dev_err(&pdev->dev, "missing platform data\n");
153 return -ENOENT;
154 }
155
156 encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
157 input = input_allocate_device();
158 if (!encoder || !input) {
159 dev_err(&pdev->dev, "failed to allocate memory for device\n");
160 err = -ENOMEM;
161 goto exit_free_mem;
162 }
163
164 encoder->input = input;
165 encoder->pdata = pdata;
166 encoder->irq_a = gpio_to_irq(pdata->gpio_a);
167 encoder->irq_b = gpio_to_irq(pdata->gpio_b);
168
169 /* create and register the input driver */
170 input->name = pdev->name;
171 input->id.bustype = BUS_HOST;
172 input->dev.parent = &pdev->dev;
173
174 if (pdata->relative_axis) {
175 input->evbit[0] = BIT_MASK(EV_REL);
176 input->relbit[0] = BIT_MASK(pdata->axis);
177 } else {
178 input->evbit[0] = BIT_MASK(EV_ABS);
179 input_set_abs_params(encoder->input,
180 pdata->axis, 0, pdata->steps, 0, 1);
181 }
182
183 err = input_register_device(input);
184 if (err) {
185 dev_err(&pdev->dev, "failed to register input device\n");
186 goto exit_free_mem;
187 }
188
189 /* request the GPIOs */
190 err = gpio_request(pdata->gpio_a, DRV_NAME);
191 if (err) {
192 dev_err(&pdev->dev, "unable to request GPIO %d\n",
193 pdata->gpio_a);
194 goto exit_unregister_input;
195 }
196
197 err = gpio_direction_input(pdata->gpio_a);
198 if (err) {
199 dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
200 pdata->gpio_a);
201 goto exit_unregister_input;
202 }
203
204 err = gpio_request(pdata->gpio_b, DRV_NAME);
205 if (err) {
206 dev_err(&pdev->dev, "unable to request GPIO %d\n",
207 pdata->gpio_b);
208 goto exit_free_gpio_a;
209 }
210
211 err = gpio_direction_input(pdata->gpio_b);
212 if (err) {
213 dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
214 pdata->gpio_b);
215 goto exit_free_gpio_a;
216 }
217
218 /* request the IRQs */
219 if (pdata->half_period) {
220 handler = &rotary_encoder_half_period_irq;
221 encoder->last_stable = rotary_encoder_get_state(pdata);
222 } else {
223 handler = &rotary_encoder_irq;
224 }
225
226 err = request_irq(encoder->irq_a, handler,
227 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
228 DRV_NAME, encoder);
229 if (err) {
230 dev_err(&pdev->dev, "unable to request IRQ %d\n",
231 encoder->irq_a);
232 goto exit_free_gpio_b;
233 }
234
235 err = request_irq(encoder->irq_b, handler,
236 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
237 DRV_NAME, encoder);
238 if (err) {
239 dev_err(&pdev->dev, "unable to request IRQ %d\n",
240 encoder->irq_b);
241 goto exit_free_irq_a;
242 }
243
244 platform_set_drvdata(pdev, encoder);
245
246 return 0;
247
248exit_free_irq_a:
249 free_irq(encoder->irq_a, encoder);
250exit_free_gpio_b:
251 gpio_free(pdata->gpio_b);
252exit_free_gpio_a:
253 gpio_free(pdata->gpio_a);
254exit_unregister_input:
255 input_unregister_device(input);
256 input = NULL; /* so we don't try to free it */
257exit_free_mem:
258 input_free_device(input);
259 kfree(encoder);
260 return err;
261}
262
263static int __devexit rotary_encoder_remove(struct platform_device *pdev)
264{
265 struct rotary_encoder *encoder = platform_get_drvdata(pdev);
266 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
267
268 free_irq(encoder->irq_a, encoder);
269 free_irq(encoder->irq_b, encoder);
270 gpio_free(pdata->gpio_a);
271 gpio_free(pdata->gpio_b);
272 input_unregister_device(encoder->input);
273 platform_set_drvdata(pdev, NULL);
274 kfree(encoder);
275
276 return 0;
277}
278
279static struct platform_driver rotary_encoder_driver = {
280 .probe = rotary_encoder_probe,
281 .remove = __devexit_p(rotary_encoder_remove),
282 .driver = {
283 .name = DRV_NAME,
284 .owner = THIS_MODULE,
285 }
286};
287
288static int __init rotary_encoder_init(void)
289{
290 return platform_driver_register(&rotary_encoder_driver);
291}
292
293static void __exit rotary_encoder_exit(void)
294{
295 platform_driver_unregister(&rotary_encoder_driver);
296}
297
298module_init(rotary_encoder_init);
299module_exit(rotary_encoder_exit);
300
301MODULE_ALIAS("platform:" DRV_NAME);
302MODULE_DESCRIPTION("GPIO rotary encoder driver");
303MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
304MODULE_LICENSE("GPL v2");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * rotary_encoder.c
4 *
5 * (c) 2009 Daniel Mack <daniel@caiaq.de>
6 * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
7 *
8 * state machine code inspired by code from Tim Ruetz
9 *
10 * A generic driver for rotary encoders connected to GPIO lines.
11 * See file:Documentation/input/devices/rotary-encoder.rst for more information
12 */
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/interrupt.h>
17#include <linux/input.h>
18#include <linux/device.h>
19#include <linux/platform_device.h>
20#include <linux/gpio/consumer.h>
21#include <linux/slab.h>
22#include <linux/of.h>
23#include <linux/pm.h>
24#include <linux/property.h>
25
26#define DRV_NAME "rotary-encoder"
27
28enum rotary_encoder_encoding {
29 ROTENC_GRAY,
30 ROTENC_BINARY,
31};
32
33struct rotary_encoder {
34 struct input_dev *input;
35
36 struct mutex access_mutex;
37
38 u32 steps;
39 u32 axis;
40 bool relative_axis;
41 bool rollover;
42 enum rotary_encoder_encoding encoding;
43
44 unsigned int pos;
45
46 struct gpio_descs *gpios;
47
48 unsigned int *irq;
49
50 bool armed;
51 signed char dir; /* 1 - clockwise, -1 - CCW */
52
53 unsigned int last_stable;
54};
55
56static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
57{
58 int i;
59 unsigned int ret = 0;
60
61 for (i = 0; i < encoder->gpios->ndescs; ++i) {
62 int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);
63
64 /* convert from gray encoding to normal */
65 if (encoder->encoding == ROTENC_GRAY && ret & 1)
66 val = !val;
67
68 ret = ret << 1 | val;
69 }
70
71 return ret & 3;
72}
73
74static void rotary_encoder_report_event(struct rotary_encoder *encoder)
75{
76 if (encoder->relative_axis) {
77 input_report_rel(encoder->input,
78 encoder->axis, encoder->dir);
79 } else {
80 unsigned int pos = encoder->pos;
81
82 if (encoder->dir < 0) {
83 /* turning counter-clockwise */
84 if (encoder->rollover)
85 pos += encoder->steps;
86 if (pos)
87 pos--;
88 } else {
89 /* turning clockwise */
90 if (encoder->rollover || pos < encoder->steps)
91 pos++;
92 }
93
94 if (encoder->rollover)
95 pos %= encoder->steps;
96
97 encoder->pos = pos;
98 input_report_abs(encoder->input, encoder->axis, encoder->pos);
99 }
100
101 input_sync(encoder->input);
102}
103
104static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
105{
106 struct rotary_encoder *encoder = dev_id;
107 unsigned int state;
108
109 mutex_lock(&encoder->access_mutex);
110
111 state = rotary_encoder_get_state(encoder);
112
113 switch (state) {
114 case 0x0:
115 if (encoder->armed) {
116 rotary_encoder_report_event(encoder);
117 encoder->armed = false;
118 }
119 break;
120
121 case 0x1:
122 case 0x3:
123 if (encoder->armed)
124 encoder->dir = 2 - state;
125 break;
126
127 case 0x2:
128 encoder->armed = true;
129 break;
130 }
131
132 mutex_unlock(&encoder->access_mutex);
133
134 return IRQ_HANDLED;
135}
136
137static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
138{
139 struct rotary_encoder *encoder = dev_id;
140 unsigned int state;
141
142 mutex_lock(&encoder->access_mutex);
143
144 state = rotary_encoder_get_state(encoder);
145
146 if (state & 1) {
147 encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
148 } else {
149 if (state != encoder->last_stable) {
150 rotary_encoder_report_event(encoder);
151 encoder->last_stable = state;
152 }
153 }
154
155 mutex_unlock(&encoder->access_mutex);
156
157 return IRQ_HANDLED;
158}
159
160static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
161{
162 struct rotary_encoder *encoder = dev_id;
163 unsigned int state;
164
165 mutex_lock(&encoder->access_mutex);
166
167 state = rotary_encoder_get_state(encoder);
168
169 if ((encoder->last_stable + 1) % 4 == state)
170 encoder->dir = 1;
171 else if (encoder->last_stable == (state + 1) % 4)
172 encoder->dir = -1;
173 else
174 goto out;
175
176 rotary_encoder_report_event(encoder);
177
178out:
179 encoder->last_stable = state;
180 mutex_unlock(&encoder->access_mutex);
181
182 return IRQ_HANDLED;
183}
184
185static int rotary_encoder_probe(struct platform_device *pdev)
186{
187 struct device *dev = &pdev->dev;
188 struct rotary_encoder *encoder;
189 struct input_dev *input;
190 irq_handler_t handler;
191 u32 steps_per_period;
192 unsigned int i;
193 int err;
194
195 encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
196 if (!encoder)
197 return -ENOMEM;
198
199 mutex_init(&encoder->access_mutex);
200
201 device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);
202
203 err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
204 &steps_per_period);
205 if (err) {
206 /*
207 * The 'half-period' property has been deprecated, you must
208 * use 'steps-per-period' and set an appropriate value, but
209 * we still need to parse it to maintain compatibility. If
210 * neither property is present we fall back to the one step
211 * per period behavior.
212 */
213 steps_per_period = device_property_read_bool(dev,
214 "rotary-encoder,half-period") ? 2 : 1;
215 }
216
217 encoder->rollover =
218 device_property_read_bool(dev, "rotary-encoder,rollover");
219
220 if (!device_property_present(dev, "rotary-encoder,encoding") ||
221 !device_property_match_string(dev, "rotary-encoder,encoding",
222 "gray")) {
223 dev_info(dev, "gray");
224 encoder->encoding = ROTENC_GRAY;
225 } else if (!device_property_match_string(dev, "rotary-encoder,encoding",
226 "binary")) {
227 dev_info(dev, "binary");
228 encoder->encoding = ROTENC_BINARY;
229 } else {
230 dev_err(dev, "unknown encoding setting\n");
231 return -EINVAL;
232 }
233
234 device_property_read_u32(dev, "linux,axis", &encoder->axis);
235 encoder->relative_axis =
236 device_property_read_bool(dev, "rotary-encoder,relative-axis");
237
238 encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
239 if (IS_ERR(encoder->gpios)) {
240 err = PTR_ERR(encoder->gpios);
241 if (err != -EPROBE_DEFER)
242 dev_err(dev, "unable to get gpios: %d\n", err);
243 return err;
244 }
245 if (encoder->gpios->ndescs < 2) {
246 dev_err(dev, "not enough gpios found\n");
247 return -EINVAL;
248 }
249
250 input = devm_input_allocate_device(dev);
251 if (!input)
252 return -ENOMEM;
253
254 encoder->input = input;
255
256 input->name = pdev->name;
257 input->id.bustype = BUS_HOST;
258 input->dev.parent = dev;
259
260 if (encoder->relative_axis)
261 input_set_capability(input, EV_REL, encoder->axis);
262 else
263 input_set_abs_params(input,
264 encoder->axis, 0, encoder->steps, 0, 1);
265
266 switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
267 case 4:
268 handler = &rotary_encoder_quarter_period_irq;
269 encoder->last_stable = rotary_encoder_get_state(encoder);
270 break;
271 case 2:
272 handler = &rotary_encoder_half_period_irq;
273 encoder->last_stable = rotary_encoder_get_state(encoder);
274 break;
275 case 1:
276 handler = &rotary_encoder_irq;
277 break;
278 default:
279 dev_err(dev, "'%d' is not a valid steps-per-period value\n",
280 steps_per_period);
281 return -EINVAL;
282 }
283
284 encoder->irq =
285 devm_kcalloc(dev,
286 encoder->gpios->ndescs, sizeof(*encoder->irq),
287 GFP_KERNEL);
288 if (!encoder->irq)
289 return -ENOMEM;
290
291 for (i = 0; i < encoder->gpios->ndescs; ++i) {
292 encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
293
294 err = devm_request_threaded_irq(dev, encoder->irq[i],
295 NULL, handler,
296 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
297 IRQF_ONESHOT,
298 DRV_NAME, encoder);
299 if (err) {
300 dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
301 encoder->irq[i], i);
302 return err;
303 }
304 }
305
306 err = input_register_device(input);
307 if (err) {
308 dev_err(dev, "failed to register input device\n");
309 return err;
310 }
311
312 device_init_wakeup(dev,
313 device_property_read_bool(dev, "wakeup-source"));
314
315 platform_set_drvdata(pdev, encoder);
316
317 return 0;
318}
319
320static int __maybe_unused rotary_encoder_suspend(struct device *dev)
321{
322 struct rotary_encoder *encoder = dev_get_drvdata(dev);
323 unsigned int i;
324
325 if (device_may_wakeup(dev)) {
326 for (i = 0; i < encoder->gpios->ndescs; ++i)
327 enable_irq_wake(encoder->irq[i]);
328 }
329
330 return 0;
331}
332
333static int __maybe_unused rotary_encoder_resume(struct device *dev)
334{
335 struct rotary_encoder *encoder = dev_get_drvdata(dev);
336 unsigned int i;
337
338 if (device_may_wakeup(dev)) {
339 for (i = 0; i < encoder->gpios->ndescs; ++i)
340 disable_irq_wake(encoder->irq[i]);
341 }
342
343 return 0;
344}
345
346static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
347 rotary_encoder_suspend, rotary_encoder_resume);
348
349#ifdef CONFIG_OF
350static const struct of_device_id rotary_encoder_of_match[] = {
351 { .compatible = "rotary-encoder", },
352 { },
353};
354MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
355#endif
356
357static struct platform_driver rotary_encoder_driver = {
358 .probe = rotary_encoder_probe,
359 .driver = {
360 .name = DRV_NAME,
361 .pm = &rotary_encoder_pm_ops,
362 .of_match_table = of_match_ptr(rotary_encoder_of_match),
363 }
364};
365module_platform_driver(rotary_encoder_driver);
366
367MODULE_ALIAS("platform:" DRV_NAME);
368MODULE_DESCRIPTION("GPIO rotary encoder driver");
369MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
370MODULE_LICENSE("GPL v2");