4 * (c) 2009 Daniel Mack <daniel@caiaq.de>
6 * state machine code inspired by code from Tim Ruetz
8 * A generic driver for rotary encoders connected to GPIO lines.
9 * See file:Documentation/input/rotary_encoder.txt for more information
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.
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>
26 #define DRV_NAME "rotary-encoder"
28 struct rotary_encoder {
29 struct input_dev *input;
30 struct rotary_encoder_platform_data *pdata;
39 unsigned char dir; /* 0 - clockwise, 1 - CCW */
42 static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
44 struct rotary_encoder *encoder = dev_id;
45 struct rotary_encoder_platform_data *pdata = encoder->pdata;
46 int a = !!gpio_get_value(pdata->gpio_a);
47 int b = !!gpio_get_value(pdata->gpio_b);
50 a ^= pdata->inverted_a;
51 b ^= pdata->inverted_b;
60 if (pdata->relative_axis) {
61 input_report_rel(encoder->input, pdata->axis,
62 encoder->dir ? -1 : 1);
64 unsigned int pos = encoder->pos;
67 /* turning counter-clockwise */
73 /* turning clockwise */
74 if (pdata->rollover || pos < pdata->steps)
80 input_report_abs(encoder->input, pdata->axis,
83 input_sync(encoder->input);
85 encoder->armed = false;
91 encoder->dir = state - 1;
95 encoder->armed = true;
102 static int __devinit rotary_encoder_probe(struct platform_device *pdev)
104 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
105 struct rotary_encoder *encoder;
106 struct input_dev *input;
109 if (!pdata || !pdata->steps) {
110 dev_err(&pdev->dev, "invalid platform data\n");
114 encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
115 input = input_allocate_device();
116 if (!encoder || !input) {
117 dev_err(&pdev->dev, "failed to allocate memory for device\n");
122 encoder->input = input;
123 encoder->pdata = pdata;
124 encoder->irq_a = gpio_to_irq(pdata->gpio_a);
125 encoder->irq_b = gpio_to_irq(pdata->gpio_b);
127 /* create and register the input driver */
128 input->name = pdev->name;
129 input->id.bustype = BUS_HOST;
130 input->dev.parent = &pdev->dev;
132 if (pdata->relative_axis) {
133 input->evbit[0] = BIT_MASK(EV_REL);
134 input->relbit[0] = BIT_MASK(pdata->axis);
136 input->evbit[0] = BIT_MASK(EV_ABS);
137 input_set_abs_params(encoder->input,
138 pdata->axis, 0, pdata->steps, 0, 1);
141 err = input_register_device(input);
143 dev_err(&pdev->dev, "failed to register input device\n");
147 /* request the GPIOs */
148 err = gpio_request(pdata->gpio_a, DRV_NAME);
150 dev_err(&pdev->dev, "unable to request GPIO %d\n",
152 goto exit_unregister_input;
155 err = gpio_request(pdata->gpio_b, DRV_NAME);
157 dev_err(&pdev->dev, "unable to request GPIO %d\n",
159 goto exit_free_gpio_a;
162 /* request the IRQs */
163 err = request_irq(encoder->irq_a, &rotary_encoder_irq,
164 IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
167 dev_err(&pdev->dev, "unable to request IRQ %d\n",
169 goto exit_free_gpio_b;
172 err = request_irq(encoder->irq_b, &rotary_encoder_irq,
173 IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
176 dev_err(&pdev->dev, "unable to request IRQ %d\n",
178 goto exit_free_irq_a;
181 platform_set_drvdata(pdev, encoder);
186 free_irq(encoder->irq_a, encoder);
188 gpio_free(pdata->gpio_b);
190 gpio_free(pdata->gpio_a);
191 exit_unregister_input:
192 input_unregister_device(input);
193 input = NULL; /* so we don't try to free it */
195 input_free_device(input);
200 static int __devexit rotary_encoder_remove(struct platform_device *pdev)
202 struct rotary_encoder *encoder = platform_get_drvdata(pdev);
203 struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
205 free_irq(encoder->irq_a, encoder);
206 free_irq(encoder->irq_b, encoder);
207 gpio_free(pdata->gpio_a);
208 gpio_free(pdata->gpio_b);
209 input_unregister_device(encoder->input);
210 platform_set_drvdata(pdev, NULL);
216 static struct platform_driver rotary_encoder_driver = {
217 .probe = rotary_encoder_probe,
218 .remove = __devexit_p(rotary_encoder_remove),
221 .owner = THIS_MODULE,
225 static int __init rotary_encoder_init(void)
227 return platform_driver_register(&rotary_encoder_driver);
230 static void __exit rotary_encoder_exit(void)
232 platform_driver_unregister(&rotary_encoder_driver);
235 module_init(rotary_encoder_init);
236 module_exit(rotary_encoder_exit);
238 MODULE_ALIAS("platform:" DRV_NAME);
239 MODULE_DESCRIPTION("GPIO rotary encoder driver");
240 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
241 MODULE_LICENSE("GPL v2");