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Daniel Mack73969ff2009-03-04 23:27:14 -08001/*
2 * rotary_encoder.c
3 *
4 * (c) 2009 Daniel Mack <daniel@caiaq.de>
5 *
6 * state machine code inspired by code from Tim Ruetz
7 *
8 * A generic driver for rotary encoders connected to GPIO lines.
9 * See file:Documentation/input/rotary_encoder.txt for more information
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 */
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/init.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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090025#include <linux/slab.h>
Daniel Mack73969ff2009-03-04 23:27:14 -080026
27#define DRV_NAME "rotary-encoder"
28
29struct rotary_encoder {
Daniel Mack73969ff2009-03-04 23:27:14 -080030 struct input_dev *input;
31 struct rotary_encoder_platform_data *pdata;
H Hartley Sweetenbd3ce652009-04-17 20:12:35 -070032
33 unsigned int axis;
34 unsigned int pos;
35
36 unsigned int irq_a;
37 unsigned int irq_b;
38
39 bool armed;
40 unsigned char dir; /* 0 - clockwise, 1 - CCW */
Daniel Mack73969ff2009-03-04 23:27:14 -080041};
42
Johan Hovold521a8f52011-05-11 16:33:50 -070043static int rotary_encoder_get_state(struct rotary_encoder_platform_data *pdata)
Daniel Mack73969ff2009-03-04 23:27:14 -080044{
Daniel Mack73969ff2009-03-04 23:27:14 -080045 int a = !!gpio_get_value(pdata->gpio_a);
46 int b = !!gpio_get_value(pdata->gpio_b);
Daniel Mack73969ff2009-03-04 23:27:14 -080047
48 a ^= pdata->inverted_a;
49 b ^= pdata->inverted_b;
Johan Hovold521a8f52011-05-11 16:33:50 -070050
51 return ((a << 1) | b);
52}
53
54static void rotary_encoder_report_event(struct rotary_encoder *encoder)
55{
56 struct rotary_encoder_platform_data *pdata = encoder->pdata;
57
58 if (pdata->relative_axis) {
59 input_report_rel(encoder->input,
60 pdata->axis, encoder->dir ? -1 : 1);
61 } else {
62 unsigned int pos = encoder->pos;
63
64 if (encoder->dir) {
65 /* turning counter-clockwise */
66 if (pdata->rollover)
67 pos += pdata->steps;
68 if (pos)
69 pos--;
70 } else {
71 /* turning clockwise */
72 if (pdata->rollover || pos < pdata->steps)
73 pos++;
74 }
75
76 if (pdata->rollover)
77 pos %= pdata->steps;
78
79 encoder->pos = pos;
80 input_report_abs(encoder->input, pdata->axis, encoder->pos);
81 }
82
83 input_sync(encoder->input);
84}
85
86static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
87{
88 struct rotary_encoder *encoder = dev_id;
89 int state;
90
91 state = rotary_encoder_get_state(encoder->pdata);
Daniel Mack73969ff2009-03-04 23:27:14 -080092
93 switch (state) {
Daniel Mack73969ff2009-03-04 23:27:14 -080094 case 0x0:
Johan Hovold521a8f52011-05-11 16:33:50 -070095 if (encoder->armed) {
96 rotary_encoder_report_event(encoder);
97 encoder->armed = false;
H Hartley Sweetenbd3ce652009-04-17 20:12:35 -070098 }
Daniel Mack73969ff2009-03-04 23:27:14 -080099 break;
100
101 case 0x1:
102 case 0x2:
103 if (encoder->armed)
104 encoder->dir = state - 1;
105 break;
106
107 case 0x3:
H Hartley Sweetenbd3ce652009-04-17 20:12:35 -0700108 encoder->armed = true;
Daniel Mack73969ff2009-03-04 23:27:14 -0800109 break;
110 }
111
112 return IRQ_HANDLED;
113}
114
115static int __devinit rotary_encoder_probe(struct platform_device *pdev)
116{
117 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
118 struct rotary_encoder *encoder;
119 struct input_dev *input;
120 int err;
121
H Hartley Sweeten06ee3d32009-10-05 21:43:42 -0700122 if (!pdata) {
123 dev_err(&pdev->dev, "missing platform data\n");
Daniel Mack73969ff2009-03-04 23:27:14 -0800124 return -ENOENT;
125 }
126
127 encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
128 input = input_allocate_device();
129 if (!encoder || !input) {
130 dev_err(&pdev->dev, "failed to allocate memory for device\n");
131 err = -ENOMEM;
132 goto exit_free_mem;
133 }
134
135 encoder->input = input;
136 encoder->pdata = pdata;
137 encoder->irq_a = gpio_to_irq(pdata->gpio_a);
138 encoder->irq_b = gpio_to_irq(pdata->gpio_b);
139
140 /* create and register the input driver */
141 input->name = pdev->name;
142 input->id.bustype = BUS_HOST;
143 input->dev.parent = &pdev->dev;
H Hartley Sweetenbd3ce652009-04-17 20:12:35 -0700144
145 if (pdata->relative_axis) {
146 input->evbit[0] = BIT_MASK(EV_REL);
147 input->relbit[0] = BIT_MASK(pdata->axis);
148 } else {
149 input->evbit[0] = BIT_MASK(EV_ABS);
150 input_set_abs_params(encoder->input,
151 pdata->axis, 0, pdata->steps, 0, 1);
152 }
Daniel Mack73969ff2009-03-04 23:27:14 -0800153
154 err = input_register_device(input);
155 if (err) {
156 dev_err(&pdev->dev, "failed to register input device\n");
157 goto exit_free_mem;
158 }
159
160 /* request the GPIOs */
161 err = gpio_request(pdata->gpio_a, DRV_NAME);
162 if (err) {
163 dev_err(&pdev->dev, "unable to request GPIO %d\n",
164 pdata->gpio_a);
165 goto exit_unregister_input;
166 }
167
Andrew Clayton5deeac92010-02-10 23:18:05 -0800168 err = gpio_direction_input(pdata->gpio_a);
169 if (err) {
170 dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
171 pdata->gpio_a);
172 goto exit_unregister_input;
173 }
174
Daniel Mack73969ff2009-03-04 23:27:14 -0800175 err = gpio_request(pdata->gpio_b, DRV_NAME);
176 if (err) {
177 dev_err(&pdev->dev, "unable to request GPIO %d\n",
178 pdata->gpio_b);
179 goto exit_free_gpio_a;
180 }
181
Andrew Clayton5deeac92010-02-10 23:18:05 -0800182 err = gpio_direction_input(pdata->gpio_b);
183 if (err) {
184 dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
185 pdata->gpio_b);
186 goto exit_free_gpio_a;
187 }
188
Daniel Mack73969ff2009-03-04 23:27:14 -0800189 /* request the IRQs */
190 err = request_irq(encoder->irq_a, &rotary_encoder_irq,
Alexander Steine0d5f4c2011-02-02 22:59:54 -0800191 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
Daniel Mack73969ff2009-03-04 23:27:14 -0800192 DRV_NAME, encoder);
193 if (err) {
194 dev_err(&pdev->dev, "unable to request IRQ %d\n",
195 encoder->irq_a);
196 goto exit_free_gpio_b;
197 }
198
199 err = request_irq(encoder->irq_b, &rotary_encoder_irq,
Alexander Steine0d5f4c2011-02-02 22:59:54 -0800200 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
Daniel Mack73969ff2009-03-04 23:27:14 -0800201 DRV_NAME, encoder);
202 if (err) {
203 dev_err(&pdev->dev, "unable to request IRQ %d\n",
204 encoder->irq_b);
205 goto exit_free_irq_a;
206 }
207
208 platform_set_drvdata(pdev, encoder);
209
210 return 0;
211
212exit_free_irq_a:
213 free_irq(encoder->irq_a, encoder);
214exit_free_gpio_b:
215 gpio_free(pdata->gpio_b);
216exit_free_gpio_a:
217 gpio_free(pdata->gpio_a);
218exit_unregister_input:
219 input_unregister_device(input);
220 input = NULL; /* so we don't try to free it */
221exit_free_mem:
222 input_free_device(input);
223 kfree(encoder);
224 return err;
225}
226
227static int __devexit rotary_encoder_remove(struct platform_device *pdev)
228{
229 struct rotary_encoder *encoder = platform_get_drvdata(pdev);
230 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
231
232 free_irq(encoder->irq_a, encoder);
233 free_irq(encoder->irq_b, encoder);
234 gpio_free(pdata->gpio_a);
235 gpio_free(pdata->gpio_b);
236 input_unregister_device(encoder->input);
237 platform_set_drvdata(pdev, NULL);
238 kfree(encoder);
239
240 return 0;
241}
242
243static struct platform_driver rotary_encoder_driver = {
244 .probe = rotary_encoder_probe,
245 .remove = __devexit_p(rotary_encoder_remove),
246 .driver = {
247 .name = DRV_NAME,
248 .owner = THIS_MODULE,
249 }
250};
251
252static int __init rotary_encoder_init(void)
253{
254 return platform_driver_register(&rotary_encoder_driver);
255}
256
257static void __exit rotary_encoder_exit(void)
258{
259 platform_driver_unregister(&rotary_encoder_driver);
260}
261
262module_init(rotary_encoder_init);
263module_exit(rotary_encoder_exit);
264
265MODULE_ALIAS("platform:" DRV_NAME);
266MODULE_DESCRIPTION("GPIO rotary encoder driver");
267MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
268MODULE_LICENSE("GPL v2");