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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 guard(mutex)(&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 return IRQ_HANDLED;
133}
134
135static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
136{
137 struct rotary_encoder *encoder = dev_id;
138 unsigned int state;
139
140 guard(mutex)(&encoder->access_mutex);
141
142 state = rotary_encoder_get_state(encoder);
143
144 if (state & 1) {
145 encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
146 } else {
147 if (state != encoder->last_stable) {
148 rotary_encoder_report_event(encoder);
149 encoder->last_stable = state;
150 }
151 }
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 guard(mutex)(&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 rotary_encoder_report_event(encoder);
168 } else if (encoder->last_stable == (state + 1) % 4) {
169 encoder->dir = -1;
170 rotary_encoder_report_event(encoder);
171 }
172
173 encoder->last_stable = state;
174
175 return IRQ_HANDLED;
176}
177
178static int rotary_encoder_probe(struct platform_device *pdev)
179{
180 struct device *dev = &pdev->dev;
181 struct rotary_encoder *encoder;
182 struct input_dev *input;
183 irq_handler_t handler;
184 u32 steps_per_period;
185 unsigned int i;
186 int err;
187
188 encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
189 if (!encoder)
190 return -ENOMEM;
191
192 mutex_init(&encoder->access_mutex);
193
194 device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);
195
196 err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
197 &steps_per_period);
198 if (err) {
199 /*
200 * The 'half-period' property has been deprecated, you must
201 * use 'steps-per-period' and set an appropriate value, but
202 * we still need to parse it to maintain compatibility. If
203 * neither property is present we fall back to the one step
204 * per period behavior.
205 */
206 steps_per_period = device_property_read_bool(dev,
207 "rotary-encoder,half-period") ? 2 : 1;
208 }
209
210 encoder->rollover =
211 device_property_read_bool(dev, "rotary-encoder,rollover");
212
213 if (!device_property_present(dev, "rotary-encoder,encoding") ||
214 !device_property_match_string(dev, "rotary-encoder,encoding",
215 "gray")) {
216 dev_info(dev, "gray");
217 encoder->encoding = ROTENC_GRAY;
218 } else if (!device_property_match_string(dev, "rotary-encoder,encoding",
219 "binary")) {
220 dev_info(dev, "binary");
221 encoder->encoding = ROTENC_BINARY;
222 } else {
223 dev_err(dev, "unknown encoding setting\n");
224 return -EINVAL;
225 }
226
227 device_property_read_u32(dev, "linux,axis", &encoder->axis);
228 encoder->relative_axis =
229 device_property_read_bool(dev, "rotary-encoder,relative-axis");
230
231 encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
232 if (IS_ERR(encoder->gpios))
233 return dev_err_probe(dev, PTR_ERR(encoder->gpios), "unable to get gpios\n");
234 if (encoder->gpios->ndescs < 2) {
235 dev_err(dev, "not enough gpios found\n");
236 return -EINVAL;
237 }
238
239 input = devm_input_allocate_device(dev);
240 if (!input)
241 return -ENOMEM;
242
243 encoder->input = input;
244
245 input->name = pdev->name;
246 input->id.bustype = BUS_HOST;
247
248 if (encoder->relative_axis)
249 input_set_capability(input, EV_REL, encoder->axis);
250 else
251 input_set_abs_params(input,
252 encoder->axis, 0, encoder->steps, 0, 1);
253
254 switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
255 case 4:
256 handler = &rotary_encoder_quarter_period_irq;
257 encoder->last_stable = rotary_encoder_get_state(encoder);
258 break;
259 case 2:
260 handler = &rotary_encoder_half_period_irq;
261 encoder->last_stable = rotary_encoder_get_state(encoder);
262 break;
263 case 1:
264 handler = &rotary_encoder_irq;
265 break;
266 default:
267 dev_err(dev, "'%d' is not a valid steps-per-period value\n",
268 steps_per_period);
269 return -EINVAL;
270 }
271
272 encoder->irq =
273 devm_kcalloc(dev,
274 encoder->gpios->ndescs, sizeof(*encoder->irq),
275 GFP_KERNEL);
276 if (!encoder->irq)
277 return -ENOMEM;
278
279 for (i = 0; i < encoder->gpios->ndescs; ++i) {
280 encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
281
282 err = devm_request_threaded_irq(dev, encoder->irq[i],
283 NULL, handler,
284 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
285 IRQF_ONESHOT,
286 DRV_NAME, encoder);
287 if (err) {
288 dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
289 encoder->irq[i], i);
290 return err;
291 }
292 }
293
294 err = input_register_device(input);
295 if (err) {
296 dev_err(dev, "failed to register input device\n");
297 return err;
298 }
299
300 device_init_wakeup(dev,
301 device_property_read_bool(dev, "wakeup-source"));
302
303 platform_set_drvdata(pdev, encoder);
304
305 return 0;
306}
307
308static int rotary_encoder_suspend(struct device *dev)
309{
310 struct rotary_encoder *encoder = dev_get_drvdata(dev);
311 unsigned int i;
312
313 if (device_may_wakeup(dev)) {
314 for (i = 0; i < encoder->gpios->ndescs; ++i)
315 enable_irq_wake(encoder->irq[i]);
316 }
317
318 return 0;
319}
320
321static int rotary_encoder_resume(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 disable_irq_wake(encoder->irq[i]);
329 }
330
331 return 0;
332}
333
334static DEFINE_SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
335 rotary_encoder_suspend, rotary_encoder_resume);
336
337#ifdef CONFIG_OF
338static const struct of_device_id rotary_encoder_of_match[] = {
339 { .compatible = "rotary-encoder", },
340 { },
341};
342MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
343#endif
344
345static struct platform_driver rotary_encoder_driver = {
346 .probe = rotary_encoder_probe,
347 .driver = {
348 .name = DRV_NAME,
349 .pm = pm_sleep_ptr(&rotary_encoder_pm_ops),
350 .of_match_table = of_match_ptr(rotary_encoder_of_match),
351 }
352};
353module_platform_driver(rotary_encoder_driver);
354
355MODULE_ALIAS("platform:" DRV_NAME);
356MODULE_DESCRIPTION("GPIO rotary encoder driver");
357MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
358MODULE_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.h>
24#include <linux/rotary_encoder.h>
25#include <linux/slab.h>
26#include <linux/of.h>
27#include <linux/of_platform.h>
28#include <linux/of_gpio.h>
29
30#define DRV_NAME "rotary-encoder"
31
32struct rotary_encoder {
33 struct input_dev *input;
34 const struct rotary_encoder_platform_data *pdata;
35
36 unsigned int axis;
37 unsigned int pos;
38
39 unsigned int irq_a;
40 unsigned int irq_b;
41
42 bool armed;
43 unsigned char dir; /* 0 - clockwise, 1 - CCW */
44
45 char last_stable;
46};
47
48static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
49{
50 int a = !!gpio_get_value(pdata->gpio_a);
51 int b = !!gpio_get_value(pdata->gpio_b);
52
53 a ^= pdata->inverted_a;
54 b ^= pdata->inverted_b;
55
56 return ((a << 1) | b);
57}
58
59static void rotary_encoder_report_event(struct rotary_encoder *encoder)
60{
61 const struct rotary_encoder_platform_data *pdata = encoder->pdata;
62
63 if (pdata->relative_axis) {
64 input_report_rel(encoder->input,
65 pdata->axis, encoder->dir ? -1 : 1);
66 } else {
67 unsigned int pos = encoder->pos;
68
69 if (encoder->dir) {
70 /* turning counter-clockwise */
71 if (pdata->rollover)
72 pos += pdata->steps;
73 if (pos)
74 pos--;
75 } else {
76 /* turning clockwise */
77 if (pdata->rollover || pos < pdata->steps)
78 pos++;
79 }
80
81 if (pdata->rollover)
82 pos %= pdata->steps;
83
84 encoder->pos = pos;
85 input_report_abs(encoder->input, pdata->axis, encoder->pos);
86 }
87
88 input_sync(encoder->input);
89}
90
91static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
92{
93 struct rotary_encoder *encoder = dev_id;
94 int state;
95
96 state = rotary_encoder_get_state(encoder->pdata);
97
98 switch (state) {
99 case 0x0:
100 if (encoder->armed) {
101 rotary_encoder_report_event(encoder);
102 encoder->armed = false;
103 }
104 break;
105
106 case 0x1:
107 case 0x2:
108 if (encoder->armed)
109 encoder->dir = state - 1;
110 break;
111
112 case 0x3:
113 encoder->armed = true;
114 break;
115 }
116
117 return IRQ_HANDLED;
118}
119
120static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
121{
122 struct rotary_encoder *encoder = dev_id;
123 int state;
124
125 state = rotary_encoder_get_state(encoder->pdata);
126
127 switch (state) {
128 case 0x00:
129 case 0x03:
130 if (state != encoder->last_stable) {
131 rotary_encoder_report_event(encoder);
132 encoder->last_stable = state;
133 }
134 break;
135
136 case 0x01:
137 case 0x02:
138 encoder->dir = (encoder->last_stable + state) & 0x01;
139 break;
140 }
141
142 return IRQ_HANDLED;
143}
144
145#ifdef CONFIG_OF
146static struct of_device_id rotary_encoder_of_match[] = {
147 { .compatible = "rotary-encoder", },
148 { },
149};
150MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
151
152static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
153{
154 const struct of_device_id *of_id =
155 of_match_device(rotary_encoder_of_match, dev);
156 struct device_node *np = dev->of_node;
157 struct rotary_encoder_platform_data *pdata;
158 enum of_gpio_flags flags;
159
160 if (!of_id || !np)
161 return NULL;
162
163 pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
164 GFP_KERNEL);
165 if (!pdata)
166 return ERR_PTR(-ENOMEM);
167
168 of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
169 of_property_read_u32(np, "linux,axis", &pdata->axis);
170
171 pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
172 pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
173
174 pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
175 pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
176
177 pdata->relative_axis = !!of_get_property(np,
178 "rotary-encoder,relative-axis", NULL);
179 pdata->rollover = !!of_get_property(np,
180 "rotary-encoder,rollover", NULL);
181 pdata->half_period = !!of_get_property(np,
182 "rotary-encoder,half-period", NULL);
183
184 return pdata;
185}
186#else
187static inline struct rotary_encoder_platform_data *
188rotary_encoder_parse_dt(struct device *dev)
189{
190 return NULL;
191}
192#endif
193
194static int rotary_encoder_probe(struct platform_device *pdev)
195{
196 struct device *dev = &pdev->dev;
197 const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
198 struct rotary_encoder *encoder;
199 struct input_dev *input;
200 irq_handler_t handler;
201 int err;
202
203 if (!pdata) {
204 pdata = rotary_encoder_parse_dt(dev);
205 if (IS_ERR(pdata))
206 return PTR_ERR(pdata);
207
208 if (!pdata) {
209 dev_err(dev, "missing platform data\n");
210 return -EINVAL;
211 }
212 }
213
214 encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
215 input = input_allocate_device();
216 if (!encoder || !input) {
217 err = -ENOMEM;
218 goto exit_free_mem;
219 }
220
221 encoder->input = input;
222 encoder->pdata = pdata;
223
224 input->name = pdev->name;
225 input->id.bustype = BUS_HOST;
226 input->dev.parent = dev;
227
228 if (pdata->relative_axis) {
229 input->evbit[0] = BIT_MASK(EV_REL);
230 input->relbit[0] = BIT_MASK(pdata->axis);
231 } else {
232 input->evbit[0] = BIT_MASK(EV_ABS);
233 input_set_abs_params(encoder->input,
234 pdata->axis, 0, pdata->steps, 0, 1);
235 }
236
237 /* request the GPIOs */
238 err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
239 if (err) {
240 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
241 goto exit_free_mem;
242 }
243
244 err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
245 if (err) {
246 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
247 goto exit_free_gpio_a;
248 }
249
250 encoder->irq_a = gpio_to_irq(pdata->gpio_a);
251 encoder->irq_b = gpio_to_irq(pdata->gpio_b);
252
253 /* request the IRQs */
254 if (pdata->half_period) {
255 handler = &rotary_encoder_half_period_irq;
256 encoder->last_stable = rotary_encoder_get_state(pdata);
257 } else {
258 handler = &rotary_encoder_irq;
259 }
260
261 err = request_irq(encoder->irq_a, handler,
262 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
263 DRV_NAME, encoder);
264 if (err) {
265 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
266 goto exit_free_gpio_b;
267 }
268
269 err = request_irq(encoder->irq_b, handler,
270 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
271 DRV_NAME, encoder);
272 if (err) {
273 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
274 goto exit_free_irq_a;
275 }
276
277 err = input_register_device(input);
278 if (err) {
279 dev_err(dev, "failed to register input device\n");
280 goto exit_free_irq_b;
281 }
282
283 platform_set_drvdata(pdev, encoder);
284
285 return 0;
286
287exit_free_irq_b:
288 free_irq(encoder->irq_b, encoder);
289exit_free_irq_a:
290 free_irq(encoder->irq_a, encoder);
291exit_free_gpio_b:
292 gpio_free(pdata->gpio_b);
293exit_free_gpio_a:
294 gpio_free(pdata->gpio_a);
295exit_free_mem:
296 input_free_device(input);
297 kfree(encoder);
298 if (!dev_get_platdata(&pdev->dev))
299 kfree(pdata);
300
301 return err;
302}
303
304static int rotary_encoder_remove(struct platform_device *pdev)
305{
306 struct rotary_encoder *encoder = platform_get_drvdata(pdev);
307 const struct rotary_encoder_platform_data *pdata = encoder->pdata;
308
309 free_irq(encoder->irq_a, encoder);
310 free_irq(encoder->irq_b, encoder);
311 gpio_free(pdata->gpio_a);
312 gpio_free(pdata->gpio_b);
313
314 input_unregister_device(encoder->input);
315 kfree(encoder);
316
317 if (!dev_get_platdata(&pdev->dev))
318 kfree(pdata);
319
320 return 0;
321}
322
323static struct platform_driver rotary_encoder_driver = {
324 .probe = rotary_encoder_probe,
325 .remove = rotary_encoder_remove,
326 .driver = {
327 .name = DRV_NAME,
328 .owner = THIS_MODULE,
329 .of_match_table = of_match_ptr(rotary_encoder_of_match),
330 }
331};
332module_platform_driver(rotary_encoder_driver);
333
334MODULE_ALIAS("platform:" DRV_NAME);
335MODULE_DESCRIPTION("GPIO rotary encoder driver");
336MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
337MODULE_LICENSE("GPL v2");