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/drivers/input/misc/rotary_encoder.c

https://bitbucket.org/ndreys/linux-sunxi
C | 304 lines | 232 code | 52 blank | 20 comment | 29 complexity | 51b6dc2df95daf18481632ade7238020 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/*
  2 * rotary_encoder.c
  3 *
  4 * (c) 2009 Daniel Mack <daniel@caiaq.de>
  5 * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
  6 *
  7 * state machine code inspired by code from Tim Ruetz
  8 *
  9 * A generic driver for rotary encoders connected to GPIO lines.
 10 * See file:Documentation/input/rotary_encoder.txt for more information
 11 *
 12 * This program is free software; you can redistribute it and/or modify
 13 * it under the terms of the GNU General Public License version 2 as
 14 * published by the Free Software Foundation.
 15 */
 16
 17#include <linux/kernel.h>
 18#include <linux/module.h>
 19#include <linux/init.h>
 20#include <linux/interrupt.h>
 21#include <linux/input.h>
 22#include <linux/device.h>
 23#include <linux/platform_device.h>
 24#include <linux/gpio.h>
 25#include <linux/rotary_encoder.h>
 26#include <linux/slab.h>
 27
 28#define DRV_NAME "rotary-encoder"
 29
 30struct rotary_encoder {
 31	struct input_dev *input;
 32	struct rotary_encoder_platform_data *pdata;
 33
 34	unsigned int axis;
 35	unsigned int pos;
 36
 37	unsigned int irq_a;
 38	unsigned int irq_b;
 39
 40	bool armed;
 41	unsigned char dir;	/* 0 - clockwise, 1 - CCW */
 42
 43	char last_stable;
 44};
 45
 46static int rotary_encoder_get_state(struct rotary_encoder_platform_data *pdata)
 47{
 48	int a = !!gpio_get_value(pdata->gpio_a);
 49	int b = !!gpio_get_value(pdata->gpio_b);
 50
 51	a ^= pdata->inverted_a;
 52	b ^= pdata->inverted_b;
 53
 54	return ((a << 1) | b);
 55}
 56
 57static void rotary_encoder_report_event(struct rotary_encoder *encoder)
 58{
 59	struct rotary_encoder_platform_data *pdata = encoder->pdata;
 60
 61	if (pdata->relative_axis) {
 62		input_report_rel(encoder->input,
 63				 pdata->axis, encoder->dir ? -1 : 1);
 64	} else {
 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
 79		if (pdata->rollover)
 80			pos %= pdata->steps;
 81
 82		encoder->pos = pos;
 83		input_report_abs(encoder->input, pdata->axis, encoder->pos);
 84	}
 85
 86	input_sync(encoder->input);
 87}
 88
 89static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
 90{
 91	struct rotary_encoder *encoder = dev_id;
 92	int state;
 93
 94	state = rotary_encoder_get_state(encoder->pdata);
 95
 96	switch (state) {
 97	case 0x0:
 98		if (encoder->armed) {
 99			rotary_encoder_report_event(encoder);
100			encoder->armed = false;
101		}
102		break;
103
104	case 0x1:
105	case 0x2:
106		if (encoder->armed)
107			encoder->dir = state - 1;
108		break;
109
110	case 0x3:
111		encoder->armed = true;
112		break;
113	}
114
115	return IRQ_HANDLED;
116}
117
118static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
119{
120	struct rotary_encoder *encoder = dev_id;
121	int state;
122
123	state = rotary_encoder_get_state(encoder->pdata);
124
125	switch (state) {
126	case 0x00:
127	case 0x03:
128		if (state != encoder->last_stable) {
129			rotary_encoder_report_event(encoder);
130			encoder->last_stable = state;
131		}
132		break;
133
134	case 0x01:
135	case 0x02:
136		encoder->dir = (encoder->last_stable + state) & 0x01;
137		break;
138	}
139
140	return IRQ_HANDLED;
141}
142
143static int __devinit rotary_encoder_probe(struct platform_device *pdev)
144{
145	struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
146	struct rotary_encoder *encoder;
147	struct input_dev *input;
148	irq_handler_t handler;
149	int err;
150
151	if (!pdata) {
152		dev_err(&pdev->dev, "missing platform data\n");
153		return -ENOENT;
154	}
155
156	encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
157	input = input_allocate_device();
158	if (!encoder || !input) {
159		dev_err(&pdev->dev, "failed to allocate memory for device\n");
160		err = -ENOMEM;
161		goto exit_free_mem;
162	}
163
164	encoder->input = input;
165	encoder->pdata = pdata;
166	encoder->irq_a = gpio_to_irq(pdata->gpio_a);
167	encoder->irq_b = gpio_to_irq(pdata->gpio_b);
168
169	/* create and register the input driver */
170	input->name = pdev->name;
171	input->id.bustype = BUS_HOST;
172	input->dev.parent = &pdev->dev;
173
174	if (pdata->relative_axis) {
175		input->evbit[0] = BIT_MASK(EV_REL);
176		input->relbit[0] = BIT_MASK(pdata->axis);
177	} else {
178		input->evbit[0] = BIT_MASK(EV_ABS);
179		input_set_abs_params(encoder->input,
180				     pdata->axis, 0, pdata->steps, 0, 1);
181	}
182
183	err = input_register_device(input);
184	if (err) {
185		dev_err(&pdev->dev, "failed to register input device\n");
186		goto exit_free_mem;
187	}
188
189	/* request the GPIOs */
190	err = gpio_request(pdata->gpio_a, DRV_NAME);
191	if (err) {
192		dev_err(&pdev->dev, "unable to request GPIO %d\n",
193			pdata->gpio_a);
194		goto exit_unregister_input;
195	}
196
197	err = gpio_direction_input(pdata->gpio_a);
198	if (err) {
199		dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
200			pdata->gpio_a);
201		goto exit_unregister_input;
202	}
203
204	err = gpio_request(pdata->gpio_b, DRV_NAME);
205	if (err) {
206		dev_err(&pdev->dev, "unable to request GPIO %d\n",
207			pdata->gpio_b);
208		goto exit_free_gpio_a;
209	}
210
211	err = gpio_direction_input(pdata->gpio_b);
212	if (err) {
213		dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
214			pdata->gpio_b);
215		goto exit_free_gpio_a;
216	}
217
218	/* request the IRQs */
219	if (pdata->half_period) {
220		handler = &rotary_encoder_half_period_irq;
221		encoder->last_stable = rotary_encoder_get_state(pdata);
222	} else {
223		handler = &rotary_encoder_irq;
224	}
225
226	err = request_irq(encoder->irq_a, handler,
227			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
228			  DRV_NAME, encoder);
229	if (err) {
230		dev_err(&pdev->dev, "unable to request IRQ %d\n",
231			encoder->irq_a);
232		goto exit_free_gpio_b;
233	}
234
235	err = request_irq(encoder->irq_b, handler,
236			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
237			  DRV_NAME, encoder);
238	if (err) {
239		dev_err(&pdev->dev, "unable to request IRQ %d\n",
240			encoder->irq_b);
241		goto exit_free_irq_a;
242	}
243
244	platform_set_drvdata(pdev, encoder);
245
246	return 0;
247
248exit_free_irq_a:
249	free_irq(encoder->irq_a, encoder);
250exit_free_gpio_b:
251	gpio_free(pdata->gpio_b);
252exit_free_gpio_a:
253	gpio_free(pdata->gpio_a);
254exit_unregister_input:
255	input_unregister_device(input);
256	input = NULL; /* so we don't try to free it */
257exit_free_mem:
258	input_free_device(input);
259	kfree(encoder);
260	return err;
261}
262
263static int __devexit rotary_encoder_remove(struct platform_device *pdev)
264{
265	struct rotary_encoder *encoder = platform_get_drvdata(pdev);
266	struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
267
268	free_irq(encoder->irq_a, encoder);
269	free_irq(encoder->irq_b, encoder);
270	gpio_free(pdata->gpio_a);
271	gpio_free(pdata->gpio_b);
272	input_unregister_device(encoder->input);
273	platform_set_drvdata(pdev, NULL);
274	kfree(encoder);
275
276	return 0;
277}
278
279static struct platform_driver rotary_encoder_driver = {
280	.probe		= rotary_encoder_probe,
281	.remove		= __devexit_p(rotary_encoder_remove),
282	.driver		= {
283		.name	= DRV_NAME,
284		.owner	= THIS_MODULE,
285	}
286};
287
288static int __init rotary_encoder_init(void)
289{
290	return platform_driver_register(&rotary_encoder_driver);
291}
292
293static void __exit rotary_encoder_exit(void)
294{
295	platform_driver_unregister(&rotary_encoder_driver);
296}
297
298module_init(rotary_encoder_init);
299module_exit(rotary_encoder_exit);
300
301MODULE_ALIAS("platform:" DRV_NAME);
302MODULE_DESCRIPTION("GPIO rotary encoder driver");
303MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
304MODULE_LICENSE("GPL v2");