1
2
3
4
5
6
7
8
9
10
11
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;
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
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
84 if (encoder->rollover)
85 pos += encoder->steps;
86 if (pos)
87 pos--;
88 } else {
89
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
208
209
210
211
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");
371
