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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.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");