30ec77ad32c6efa6a56637246e342bad5b7e93b1
[sfrench/cifs-2.6.git] / drivers / input / misc / rotary_encoder.c
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/devices/rotary-encoder.rst 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
31 enum rotary_encoder_encoding {
32         ROTENC_GRAY,
33         ROTENC_BINARY,
34 };
35
36 struct 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
59 static 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
77 static 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
107 static 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
140 static 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
163 static 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
181 out:
182         encoder->last_stable = state;
183         mutex_unlock(&encoder->access_mutex);
184
185         return IRQ_HANDLED;
186 }
187
188 static 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_kcalloc(dev,
287                              encoder->gpios->ndescs, sizeof(*encoder->irq),
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
321 static 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
334 static 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
347 static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
348                          rotary_encoder_suspend, rotary_encoder_resume);
349
350 #ifdef CONFIG_OF
351 static const struct of_device_id rotary_encoder_of_match[] = {
352         { .compatible = "rotary-encoder", },
353         { },
354 };
355 MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
356 #endif
357
358 static 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 };
366 module_platform_driver(rotary_encoder_driver);
367
368 MODULE_ALIAS("platform:" DRV_NAME);
369 MODULE_DESCRIPTION("GPIO rotary encoder driver");
370 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
371 MODULE_LICENSE("GPL v2");