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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/*
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");