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73969ff0 DM |
1 | /* |
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> | |
5a0e3ad6 | 25 | #include <linux/slab.h> |
73969ff0 DM |
26 | |
27 | #define DRV_NAME "rotary-encoder" | |
28 | ||
29 | struct rotary_encoder { | |
73969ff0 DM |
30 | struct input_dev *input; |
31 | struct rotary_encoder_platform_data *pdata; | |
bd3ce655 HS |
32 | |
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 */ | |
73969ff0 DM |
41 | }; |
42 | ||
43 | static irqreturn_t rotary_encoder_irq(int irq, void *dev_id) | |
44 | { | |
45 | struct rotary_encoder *encoder = dev_id; | |
46 | struct rotary_encoder_platform_data *pdata = encoder->pdata; | |
47 | int a = !!gpio_get_value(pdata->gpio_a); | |
48 | int b = !!gpio_get_value(pdata->gpio_b); | |
49 | int state; | |
50 | ||
51 | a ^= pdata->inverted_a; | |
52 | b ^= pdata->inverted_b; | |
53 | state = (a << 1) | b; | |
54 | ||
55 | switch (state) { | |
56 | ||
57 | case 0x0: | |
58 | if (!encoder->armed) | |
59 | break; | |
60 | ||
bd3ce655 HS |
61 | if (pdata->relative_axis) { |
62 | input_report_rel(encoder->input, pdata->axis, | |
63 | encoder->dir ? -1 : 1); | |
73969ff0 | 64 | } else { |
bd3ce655 HS |
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 | if (pdata->rollover) | |
79 | pos %= pdata->steps; | |
80 | encoder->pos = pos; | |
81 | input_report_abs(encoder->input, pdata->axis, | |
82 | encoder->pos); | |
73969ff0 | 83 | } |
73969ff0 DM |
84 | input_sync(encoder->input); |
85 | ||
bd3ce655 | 86 | encoder->armed = false; |
73969ff0 DM |
87 | break; |
88 | ||
89 | case 0x1: | |
90 | case 0x2: | |
91 | if (encoder->armed) | |
92 | encoder->dir = state - 1; | |
93 | break; | |
94 | ||
95 | case 0x3: | |
bd3ce655 | 96 | encoder->armed = true; |
73969ff0 DM |
97 | break; |
98 | } | |
99 | ||
100 | return IRQ_HANDLED; | |
101 | } | |
102 | ||
103 | static int __devinit rotary_encoder_probe(struct platform_device *pdev) | |
104 | { | |
105 | struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data; | |
106 | struct rotary_encoder *encoder; | |
107 | struct input_dev *input; | |
108 | int err; | |
109 | ||
06ee3d3c HS |
110 | if (!pdata) { |
111 | dev_err(&pdev->dev, "missing platform data\n"); | |
73969ff0 DM |
112 | return -ENOENT; |
113 | } | |
114 | ||
115 | encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL); | |
116 | input = input_allocate_device(); | |
117 | if (!encoder || !input) { | |
118 | dev_err(&pdev->dev, "failed to allocate memory for device\n"); | |
119 | err = -ENOMEM; | |
120 | goto exit_free_mem; | |
121 | } | |
122 | ||
123 | encoder->input = input; | |
124 | encoder->pdata = pdata; | |
125 | encoder->irq_a = gpio_to_irq(pdata->gpio_a); | |
126 | encoder->irq_b = gpio_to_irq(pdata->gpio_b); | |
127 | ||
128 | /* create and register the input driver */ | |
129 | input->name = pdev->name; | |
130 | input->id.bustype = BUS_HOST; | |
131 | input->dev.parent = &pdev->dev; | |
bd3ce655 HS |
132 | |
133 | if (pdata->relative_axis) { | |
134 | input->evbit[0] = BIT_MASK(EV_REL); | |
135 | input->relbit[0] = BIT_MASK(pdata->axis); | |
136 | } else { | |
137 | input->evbit[0] = BIT_MASK(EV_ABS); | |
138 | input_set_abs_params(encoder->input, | |
139 | pdata->axis, 0, pdata->steps, 0, 1); | |
140 | } | |
73969ff0 DM |
141 | |
142 | err = input_register_device(input); | |
143 | if (err) { | |
144 | dev_err(&pdev->dev, "failed to register input device\n"); | |
145 | goto exit_free_mem; | |
146 | } | |
147 | ||
148 | /* request the GPIOs */ | |
149 | err = gpio_request(pdata->gpio_a, DRV_NAME); | |
150 | if (err) { | |
151 | dev_err(&pdev->dev, "unable to request GPIO %d\n", | |
152 | pdata->gpio_a); | |
153 | goto exit_unregister_input; | |
154 | } | |
155 | ||
5deeac99 AC |
156 | err = gpio_direction_input(pdata->gpio_a); |
157 | if (err) { | |
158 | dev_err(&pdev->dev, "unable to set GPIO %d for input\n", | |
159 | pdata->gpio_a); | |
160 | goto exit_unregister_input; | |
161 | } | |
162 | ||
73969ff0 DM |
163 | err = gpio_request(pdata->gpio_b, DRV_NAME); |
164 | if (err) { | |
165 | dev_err(&pdev->dev, "unable to request GPIO %d\n", | |
166 | pdata->gpio_b); | |
167 | goto exit_free_gpio_a; | |
168 | } | |
169 | ||
5deeac99 AC |
170 | err = gpio_direction_input(pdata->gpio_b); |
171 | if (err) { | |
172 | dev_err(&pdev->dev, "unable to set GPIO %d for input\n", | |
173 | pdata->gpio_b); | |
174 | goto exit_free_gpio_a; | |
175 | } | |
176 | ||
73969ff0 DM |
177 | /* request the IRQs */ |
178 | err = request_irq(encoder->irq_a, &rotary_encoder_irq, | |
179 | IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE, | |
180 | DRV_NAME, encoder); | |
181 | if (err) { | |
182 | dev_err(&pdev->dev, "unable to request IRQ %d\n", | |
183 | encoder->irq_a); | |
184 | goto exit_free_gpio_b; | |
185 | } | |
186 | ||
187 | err = request_irq(encoder->irq_b, &rotary_encoder_irq, | |
188 | IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE, | |
189 | DRV_NAME, encoder); | |
190 | if (err) { | |
191 | dev_err(&pdev->dev, "unable to request IRQ %d\n", | |
192 | encoder->irq_b); | |
193 | goto exit_free_irq_a; | |
194 | } | |
195 | ||
196 | platform_set_drvdata(pdev, encoder); | |
197 | ||
198 | return 0; | |
199 | ||
200 | exit_free_irq_a: | |
201 | free_irq(encoder->irq_a, encoder); | |
202 | exit_free_gpio_b: | |
203 | gpio_free(pdata->gpio_b); | |
204 | exit_free_gpio_a: | |
205 | gpio_free(pdata->gpio_a); | |
206 | exit_unregister_input: | |
207 | input_unregister_device(input); | |
208 | input = NULL; /* so we don't try to free it */ | |
209 | exit_free_mem: | |
210 | input_free_device(input); | |
211 | kfree(encoder); | |
212 | return err; | |
213 | } | |
214 | ||
215 | static int __devexit rotary_encoder_remove(struct platform_device *pdev) | |
216 | { | |
217 | struct rotary_encoder *encoder = platform_get_drvdata(pdev); | |
218 | struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data; | |
219 | ||
220 | free_irq(encoder->irq_a, encoder); | |
221 | free_irq(encoder->irq_b, encoder); | |
222 | gpio_free(pdata->gpio_a); | |
223 | gpio_free(pdata->gpio_b); | |
224 | input_unregister_device(encoder->input); | |
225 | platform_set_drvdata(pdev, NULL); | |
226 | kfree(encoder); | |
227 | ||
228 | return 0; | |
229 | } | |
230 | ||
231 | static struct platform_driver rotary_encoder_driver = { | |
232 | .probe = rotary_encoder_probe, | |
233 | .remove = __devexit_p(rotary_encoder_remove), | |
234 | .driver = { | |
235 | .name = DRV_NAME, | |
236 | .owner = THIS_MODULE, | |
237 | } | |
238 | }; | |
239 | ||
240 | static int __init rotary_encoder_init(void) | |
241 | { | |
242 | return platform_driver_register(&rotary_encoder_driver); | |
243 | } | |
244 | ||
245 | static void __exit rotary_encoder_exit(void) | |
246 | { | |
247 | platform_driver_unregister(&rotary_encoder_driver); | |
248 | } | |
249 | ||
250 | module_init(rotary_encoder_init); | |
251 | module_exit(rotary_encoder_exit); | |
252 | ||
253 | MODULE_ALIAS("platform:" DRV_NAME); | |
254 | MODULE_DESCRIPTION("GPIO rotary encoder driver"); | |
255 | MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); | |
256 | MODULE_LICENSE("GPL v2"); | |
257 |