![H Hartley Sweeten](/assets/img/avatar_default.png)
The rotary encoder driver only supports returning input events for ABS_* axes, this adds support for REL_* axes. The relative axis input event is reported as -1 for each counter-clockwise step and +1 for each clockwise step. The ability to clamp the position of ABS_* axes between 0 and a maximum of "steps" has also been added. Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Daniel Mack <daniel@caiaq.de> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
243 lines
5.6 KiB
C
243 lines
5.6 KiB
C
/*
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* rotary_encoder.c
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*
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* (c) 2009 Daniel Mack <daniel@caiaq.de>
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*
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* state machine code inspired by code from Tim Ruetz
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*
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* A generic driver for rotary encoders connected to GPIO lines.
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* See file:Documentation/input/rotary_encoder.txt for more information
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/input.h>
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#include <linux/device.h>
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#include <linux/platform_device.h>
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#include <linux/gpio.h>
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#include <linux/rotary_encoder.h>
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#define DRV_NAME "rotary-encoder"
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struct rotary_encoder {
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struct input_dev *input;
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struct rotary_encoder_platform_data *pdata;
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unsigned int axis;
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unsigned int pos;
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unsigned int irq_a;
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unsigned int irq_b;
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bool armed;
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unsigned char dir; /* 0 - clockwise, 1 - CCW */
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};
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static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
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{
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struct rotary_encoder *encoder = dev_id;
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struct rotary_encoder_platform_data *pdata = encoder->pdata;
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int a = !!gpio_get_value(pdata->gpio_a);
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int b = !!gpio_get_value(pdata->gpio_b);
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int state;
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a ^= pdata->inverted_a;
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b ^= pdata->inverted_b;
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state = (a << 1) | b;
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switch (state) {
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case 0x0:
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if (!encoder->armed)
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break;
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if (pdata->relative_axis) {
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input_report_rel(encoder->input, pdata->axis,
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encoder->dir ? -1 : 1);
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} else {
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unsigned int pos = encoder->pos;
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if (encoder->dir) {
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/* turning counter-clockwise */
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if (pdata->rollover)
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pos += pdata->steps;
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if (pos)
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pos--;
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} else {
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/* turning clockwise */
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if (pdata->rollover || pos < pdata->steps)
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pos++;
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}
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if (pdata->rollover)
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pos %= pdata->steps;
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encoder->pos = pos;
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input_report_abs(encoder->input, pdata->axis,
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encoder->pos);
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}
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input_sync(encoder->input);
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encoder->armed = false;
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break;
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case 0x1:
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case 0x2:
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if (encoder->armed)
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encoder->dir = state - 1;
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break;
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case 0x3:
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encoder->armed = true;
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break;
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}
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return IRQ_HANDLED;
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}
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static int __devinit rotary_encoder_probe(struct platform_device *pdev)
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{
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struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
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struct rotary_encoder *encoder;
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struct input_dev *input;
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int err;
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if (!pdata || !pdata->steps) {
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dev_err(&pdev->dev, "invalid platform data\n");
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return -ENOENT;
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}
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encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
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input = input_allocate_device();
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if (!encoder || !input) {
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dev_err(&pdev->dev, "failed to allocate memory for device\n");
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err = -ENOMEM;
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goto exit_free_mem;
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}
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encoder->input = input;
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encoder->pdata = pdata;
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encoder->irq_a = gpio_to_irq(pdata->gpio_a);
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encoder->irq_b = gpio_to_irq(pdata->gpio_b);
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/* create and register the input driver */
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input->name = pdev->name;
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input->id.bustype = BUS_HOST;
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input->dev.parent = &pdev->dev;
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if (pdata->relative_axis) {
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input->evbit[0] = BIT_MASK(EV_REL);
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input->relbit[0] = BIT_MASK(pdata->axis);
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} else {
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input->evbit[0] = BIT_MASK(EV_ABS);
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input_set_abs_params(encoder->input,
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pdata->axis, 0, pdata->steps, 0, 1);
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}
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err = input_register_device(input);
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if (err) {
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dev_err(&pdev->dev, "failed to register input device\n");
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goto exit_free_mem;
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}
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/* request the GPIOs */
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err = gpio_request(pdata->gpio_a, DRV_NAME);
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if (err) {
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dev_err(&pdev->dev, "unable to request GPIO %d\n",
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pdata->gpio_a);
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goto exit_unregister_input;
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}
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err = gpio_request(pdata->gpio_b, DRV_NAME);
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if (err) {
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dev_err(&pdev->dev, "unable to request GPIO %d\n",
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pdata->gpio_b);
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goto exit_free_gpio_a;
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}
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/* request the IRQs */
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err = request_irq(encoder->irq_a, &rotary_encoder_irq,
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IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
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DRV_NAME, encoder);
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if (err) {
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dev_err(&pdev->dev, "unable to request IRQ %d\n",
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encoder->irq_a);
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goto exit_free_gpio_b;
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}
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err = request_irq(encoder->irq_b, &rotary_encoder_irq,
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IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
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DRV_NAME, encoder);
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if (err) {
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dev_err(&pdev->dev, "unable to request IRQ %d\n",
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encoder->irq_b);
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goto exit_free_irq_a;
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}
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platform_set_drvdata(pdev, encoder);
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return 0;
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exit_free_irq_a:
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free_irq(encoder->irq_a, encoder);
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exit_free_gpio_b:
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gpio_free(pdata->gpio_b);
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exit_free_gpio_a:
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gpio_free(pdata->gpio_a);
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exit_unregister_input:
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input_unregister_device(input);
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input = NULL; /* so we don't try to free it */
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exit_free_mem:
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input_free_device(input);
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kfree(encoder);
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return err;
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}
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static int __devexit rotary_encoder_remove(struct platform_device *pdev)
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{
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struct rotary_encoder *encoder = platform_get_drvdata(pdev);
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struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
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free_irq(encoder->irq_a, encoder);
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free_irq(encoder->irq_b, encoder);
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gpio_free(pdata->gpio_a);
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gpio_free(pdata->gpio_b);
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input_unregister_device(encoder->input);
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platform_set_drvdata(pdev, NULL);
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kfree(encoder);
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return 0;
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}
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static struct platform_driver rotary_encoder_driver = {
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.probe = rotary_encoder_probe,
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.remove = __devexit_p(rotary_encoder_remove),
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.driver = {
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.name = DRV_NAME,
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.owner = THIS_MODULE,
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}
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};
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static int __init rotary_encoder_init(void)
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{
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return platform_driver_register(&rotary_encoder_driver);
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}
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static void __exit rotary_encoder_exit(void)
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{
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platform_driver_unregister(&rotary_encoder_driver);
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}
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module_init(rotary_encoder_init);
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module_exit(rotary_encoder_exit);
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MODULE_ALIAS("platform:" DRV_NAME);
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MODULE_DESCRIPTION("GPIO rotary encoder driver");
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MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
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MODULE_LICENSE("GPL v2");
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