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-rw-r--r--Documentation/input/rotary-encoder.txt101
-rw-r--r--drivers/input/misc/Kconfig11
-rw-r--r--drivers/input/misc/Makefile2
-rw-r--r--drivers/input/misc/rotary_encoder.c221
-rw-r--r--include/linux/rotary_encoder.h13
5 files changed, 348 insertions, 0 deletions
diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt
new file mode 100644
index 000000000000..435102a26d96
--- /dev/null
+++ b/Documentation/input/rotary-encoder.txt
@@ -0,0 +1,101 @@
1rotary-encoder - a generic driver for GPIO connected devices
2Daniel Mack <daniel@caiaq.de>, Feb 2009
3
40. Function
5-----------
6
7Rotary encoders are devices which are connected to the CPU or other
8peripherals with two wires. The outputs are phase-shifted by 90 degrees
9and by triggering on falling and rising edges, the turn direction can
10be determined.
11
12The phase diagram of these two outputs look like this:
13
14 _____ _____ _____
15 | | | | | |
16 Channel A ____| |_____| |_____| |____
17
18 : : : : : : : : : : : :
19 __ _____ _____ _____
20 | | | | | | |
21 Channel B |_____| |_____| |_____| |__
22
23 : : : : : : : : : : : :
24 Event a b c d a b c d a b c d
25
26 |<-------->|
27 one step
28
29
30For more information, please see
31 http://en.wikipedia.org/wiki/Rotary_encoder
32
33
341. Events / state machine
35-------------------------
36
37a) Rising edge on channel A, channel B in low state
38 This state is used to recognize a clockwise turn
39
40b) Rising edge on channel B, channel A in high state
41 When entering this state, the encoder is put into 'armed' state,
42 meaning that there it has seen half the way of a one-step transition.
43
44c) Falling edge on channel A, channel B in high state
45 This state is used to recognize a counter-clockwise turn
46
47d) Falling edge on channel B, channel A in low state
48 Parking position. If the encoder enters this state, a full transition
49 should have happend, unless it flipped back on half the way. The
50 'armed' state tells us about that.
51
522. Platform requirements
53------------------------
54
55As there is no hardware dependent call in this driver, the platform it is
56used with must support gpiolib. Another requirement is that IRQs must be
57able to fire on both edges.
58
59
603. Board integration
61--------------------
62
63To use this driver in your system, register a platform_device with the
64name 'rotary-encoder' and associate the IRQs and some specific platform
65data with it.
66
67struct rotary_encoder_platform_data is declared in
68include/linux/rotary-encoder.h and needs to be filled with the number of
69steps the encoder has and can carry information about externally inverted
70signals (because of used invertig buffer or other reasons).
71
72Because GPIO to IRQ mapping is platform specific, this information must
73be given in seperately to the driver. See the example below.
74
75---------<snip>---------
76
77/* board support file example */
78
79#include <linux/input.h>
80#include <linux/rotary_encoder.h>
81
82#define GPIO_ROTARY_A 1
83#define GPIO_ROTARY_B 2
84
85static struct rotary_encoder_platform_data my_rotary_encoder_info = {
86 .steps = 24,
87 .axis = ABS_X,
88 .gpio_a = GPIO_ROTARY_A,
89 .gpio_b = GPIO_ROTARY_B,
90 .inverted_a = 0,
91 .inverted_b = 0,
92};
93
94static struct platform_device rotary_encoder_device = {
95 .name = "rotary-encoder",
96 .id = 0,
97 .dev = {
98 .platform_data = &my_rotary_encoder_info,
99 }
100};
101
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 67e5553f699a..806d2e66d249 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -227,4 +227,15 @@ config INPUT_PCF50633_PMU
227 Say Y to include support for delivering PMU events via input 227 Say Y to include support for delivering PMU events via input
228 layer on NXP PCF50633. 228 layer on NXP PCF50633.
229 229
230config INPUT_GPIO_ROTARY_ENCODER
231 tristate "Rotary encoders connected to GPIO pins"
232 depends on GPIOLIB && GENERIC_GPIO
233 help
234 Say Y here to add support for rotary encoders connected to GPIO lines.
235 Check file:Documentation/incput/rotary_encoder.txt for more
236 information.
237
238 To compile this driver as a module, choose M here: the
239 module will be called rotary_encoder.
240
230endif 241endif
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index bb62e6efacf3..e86cee66c914 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -22,3 +22,5 @@ obj-$(CONFIG_INPUT_UINPUT) += uinput.o
22obj-$(CONFIG_INPUT_APANEL) += apanel.o 22obj-$(CONFIG_INPUT_APANEL) += apanel.o
23obj-$(CONFIG_INPUT_SGI_BTNS) += sgi_btns.o 23obj-$(CONFIG_INPUT_SGI_BTNS) += sgi_btns.o
24obj-$(CONFIG_INPUT_PCF50633_PMU) += pcf50633-input.o 24obj-$(CONFIG_INPUT_PCF50633_PMU) += pcf50633-input.o
25obj-$(CONFIG_INPUT_GPIO_ROTARY_ENCODER) += rotary_encoder.o
26
diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
new file mode 100644
index 000000000000..5bb3ab51b8c6
--- /dev/null
+++ b/drivers/input/misc/rotary_encoder.c
@@ -0,0 +1,221 @@
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>
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 /* turning counter-clockwise */
58 encoder->pos += pdata->steps;
59 encoder->pos--;
60 encoder->pos %= pdata->steps;
61 } else {
62 /* turning clockwise */
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 /* create and register the input driver */
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 /* request the GPIOs */
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 /* request the IRQs */
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; /* so we don't try to free it */
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
diff --git a/include/linux/rotary_encoder.h b/include/linux/rotary_encoder.h
new file mode 100644
index 000000000000..12d63a30c347
--- /dev/null
+++ b/include/linux/rotary_encoder.h
@@ -0,0 +1,13 @@
1#ifndef __ROTARY_ENCODER_H__
2#define __ROTARY_ENCODER_H__
3
4struct rotary_encoder_platform_data {
5 unsigned int steps;
6 unsigned int axis;
7 unsigned int gpio_a;
8 unsigned int gpio_b;
9 unsigned int inverted_a;
10 unsigned int inverted_b;
11};
12
13#endif /* __ROTARY_ENCODER_H__ */
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