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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>
25
26#define DRV_NAME "rotary-encoder"
27
28struct rotary_encoder {
29 unsigned int irq_a;
30 unsigned int irq_b;
31 unsigned int pos;
32 unsigned int armed;
33 unsigned int dir;
34 struct input_dev *input;
35 struct rotary_encoder_platform_data *pdata;
36};
37
38static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
39{
40 struct rotary_encoder *encoder = dev_id;
41 struct rotary_encoder_platform_data *pdata = encoder->pdata;
42 int a = !!gpio_get_value(pdata->gpio_a);
43 int b = !!gpio_get_value(pdata->gpio_b);
44 int state;
45
46 a ^= pdata->inverted_a;
47 b ^= pdata->inverted_b;
48 state = (a << 1) | b;
49
50 switch (state) {
51
52 case 0x0:
53 if (!encoder->armed)
54 break;
55
56 if (encoder->dir) {
57
58 encoder->pos += pdata->steps;
59 encoder->pos--;
60 encoder->pos %= pdata->steps;
61 } else {
62
63 encoder->pos++;
64 encoder->pos %= pdata->steps;
65 }
66
67 input_report_abs(encoder->input, pdata->axis, encoder->pos);
68 input_sync(encoder->input);
69
70 encoder->armed = 0;
71 break;
72
73 case 0x1:
74 case 0x2:
75 if (encoder->armed)
76 encoder->dir = state - 1;
77 break;
78
79 case 0x3:
80 encoder->armed = 1;
81 break;
82 }
83
84 return IRQ_HANDLED;
85}
86
87static int __devinit rotary_encoder_probe(struct platform_device *pdev)
88{
89 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
90 struct rotary_encoder *encoder;
91 struct input_dev *input;
92 int err;
93
94 if (!pdata || !pdata->steps) {
95 dev_err(&pdev->dev, "invalid platform data\n");
96 return -ENOENT;
97 }
98
99 encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
100 input = input_allocate_device();
101 if (!encoder || !input) {
102 dev_err(&pdev->dev, "failed to allocate memory for device\n");
103 err = -ENOMEM;
104 goto exit_free_mem;
105 }
106
107 encoder->input = input;
108 encoder->pdata = pdata;
109 encoder->irq_a = gpio_to_irq(pdata->gpio_a);
110 encoder->irq_b = gpio_to_irq(pdata->gpio_b);
111
112
113 input->name = pdev->name;
114 input->id.bustype = BUS_HOST;
115 input->dev.parent = &pdev->dev;
116 input->evbit[0] = BIT_MASK(EV_ABS);
117 input_set_abs_params(encoder->input,
118 pdata->axis, 0, pdata->steps, 0, 1);
119
120 err = input_register_device(input);
121 if (err) {
122 dev_err(&pdev->dev, "failed to register input device\n");
123 goto exit_free_mem;
124 }
125
126
127 err = gpio_request(pdata->gpio_a, DRV_NAME);
128 if (err) {
129 dev_err(&pdev->dev, "unable to request GPIO %d\n",
130 pdata->gpio_a);
131 goto exit_unregister_input;
132 }
133
134 err = gpio_request(pdata->gpio_b, DRV_NAME);
135 if (err) {
136 dev_err(&pdev->dev, "unable to request GPIO %d\n",
137 pdata->gpio_b);
138 goto exit_free_gpio_a;
139 }
140
141
142 err = request_irq(encoder->irq_a, &rotary_encoder_irq,
143 IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
144 DRV_NAME, encoder);
145 if (err) {
146 dev_err(&pdev->dev, "unable to request IRQ %d\n",
147 encoder->irq_a);
148 goto exit_free_gpio_b;
149 }
150
151 err = request_irq(encoder->irq_b, &rotary_encoder_irq,
152 IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
153 DRV_NAME, encoder);
154 if (err) {
155 dev_err(&pdev->dev, "unable to request IRQ %d\n",
156 encoder->irq_b);
157 goto exit_free_irq_a;
158 }
159
160 platform_set_drvdata(pdev, encoder);
161
162 return 0;
163
164exit_free_irq_a:
165 free_irq(encoder->irq_a, encoder);
166exit_free_gpio_b:
167 gpio_free(pdata->gpio_b);
168exit_free_gpio_a:
169 gpio_free(pdata->gpio_a);
170exit_unregister_input:
171 input_unregister_device(input);
172 input = NULL;
173exit_free_mem:
174 input_free_device(input);
175 kfree(encoder);
176 return err;
177}
178
179static int __devexit rotary_encoder_remove(struct platform_device *pdev)
180{
181 struct rotary_encoder *encoder = platform_get_drvdata(pdev);
182 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
183
184 free_irq(encoder->irq_a, encoder);
185 free_irq(encoder->irq_b, encoder);
186 gpio_free(pdata->gpio_a);
187 gpio_free(pdata->gpio_b);
188 input_unregister_device(encoder->input);
189 platform_set_drvdata(pdev, NULL);
190 kfree(encoder);
191
192 return 0;
193}
194
195static struct platform_driver rotary_encoder_driver = {
196 .probe = rotary_encoder_probe,
197 .remove = __devexit_p(rotary_encoder_remove),
198 .driver = {
199 .name = DRV_NAME,
200 .owner = THIS_MODULE,
201 }
202};
203
204static int __init rotary_encoder_init(void)
205{
206 return platform_driver_register(&rotary_encoder_driver);
207}
208
209static void __exit rotary_encoder_exit(void)
210{
211 platform_driver_unregister(&rotary_encoder_driver);
212}
213
214module_init(rotary_encoder_init);
215module_exit(rotary_encoder_exit);
216
217MODULE_ALIAS("platform:" DRV_NAME);
218MODULE_DESCRIPTION("GPIO rotary encoder driver");
219MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
220MODULE_LICENSE("GPL v2");
221
222
