![Daniel Mack](/assets/img/avatar_default.png)
This adds devicetree bindings to the rotary encoder driver and some documentation about how to use them. Tested on a PXA3xx platform. Signed-off-by: Daniel Mack <zonque@gmail.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
341 lines
7.8 KiB
C
341 lines
7.8 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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* Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
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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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#include <linux/slab.h>
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#include <linux/of_platform.h>
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#include <linux/of_gpio.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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const 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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char last_stable;
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};
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static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
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{
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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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a ^= pdata->inverted_a;
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b ^= pdata->inverted_b;
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return ((a << 1) | b);
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}
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static void rotary_encoder_report_event(struct rotary_encoder *encoder)
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{
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const struct rotary_encoder_platform_data *pdata = encoder->pdata;
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if (pdata->relative_axis) {
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input_report_rel(encoder->input,
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pdata->axis, 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, encoder->pos);
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}
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input_sync(encoder->input);
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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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int state;
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state = rotary_encoder_get_state(encoder->pdata);
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switch (state) {
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case 0x0:
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if (encoder->armed) {
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rotary_encoder_report_event(encoder);
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encoder->armed = false;
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}
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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 irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
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{
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struct rotary_encoder *encoder = dev_id;
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int state;
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state = rotary_encoder_get_state(encoder->pdata);
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switch (state) {
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case 0x00:
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case 0x03:
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if (state != encoder->last_stable) {
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rotary_encoder_report_event(encoder);
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encoder->last_stable = state;
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}
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break;
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case 0x01:
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case 0x02:
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encoder->dir = (encoder->last_stable + state) & 0x01;
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break;
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}
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return IRQ_HANDLED;
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}
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#ifdef CONFIG_OF
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static struct of_device_id rotary_encoder_of_match[] = {
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{ .compatible = "rotary-encoder", },
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{ },
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};
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MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
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static struct rotary_encoder_platform_data * __devinit
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rotary_encoder_parse_dt(struct device *dev)
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{
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const struct of_device_id *of_id =
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of_match_device(rotary_encoder_of_match, dev);
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struct device_node *np = dev->of_node;
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struct rotary_encoder_platform_data *pdata;
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enum of_gpio_flags flags;
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if (!of_id || !np)
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return NULL;
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pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
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GFP_KERNEL);
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if (!pdata)
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return ERR_PTR(-ENOMEM);
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of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
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of_property_read_u32(np, "linux,axis", &pdata->axis);
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pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
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pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
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pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
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pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
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pdata->relative_axis = !!of_get_property(np,
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"rotary-encoder,relative-axis", NULL);
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pdata->rollover = !!of_get_property(np,
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"rotary-encoder,rollover", NULL);
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pdata->half_period = !!of_get_property(np,
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"rotary-encoder,half-period", NULL);
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return pdata;
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}
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#else
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static inline struct rotary_encoder_platform_data *
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rotary_encoder_parse_dt(struct device *dev)
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{
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return NULL;
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}
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#endif
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static int __devinit rotary_encoder_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
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struct rotary_encoder *encoder;
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struct input_dev *input;
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irq_handler_t handler;
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int err;
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if (!pdata) {
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pdata = rotary_encoder_parse_dt(dev);
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if (IS_ERR(pdata))
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return PTR_ERR(pdata);
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if (!pdata) {
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dev_err(dev, "missing platform data\n");
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return -EINVAL;
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}
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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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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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input->name = pdev->name;
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input->id.bustype = BUS_HOST;
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input->dev.parent = 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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/* request the GPIOs */
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err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
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if (err) {
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dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
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goto exit_free_mem;
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}
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err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
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if (err) {
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dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
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goto exit_free_gpio_a;
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}
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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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/* request the IRQs */
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if (pdata->half_period) {
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handler = &rotary_encoder_half_period_irq;
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encoder->last_stable = rotary_encoder_get_state(pdata);
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} else {
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handler = &rotary_encoder_irq;
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}
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err = request_irq(encoder->irq_a, handler,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
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DRV_NAME, encoder);
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if (err) {
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dev_err(dev, "unable to request IRQ %d\n", 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, handler,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
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DRV_NAME, encoder);
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if (err) {
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dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
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goto exit_free_irq_a;
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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(dev, "failed to register input device\n");
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goto exit_free_irq_b;
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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_b:
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free_irq(encoder->irq_b, encoder);
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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_free_mem:
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input_free_device(input);
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kfree(encoder);
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if (!dev_get_platdata(&pdev->dev))
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kfree(pdata);
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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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const struct rotary_encoder_platform_data *pdata = encoder->pdata;
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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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kfree(encoder);
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if (!dev_get_platdata(&pdev->dev))
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kfree(pdata);
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platform_set_drvdata(pdev, NULL);
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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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.of_match_table = of_match_ptr(rotary_encoder_of_match),
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}
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};
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module_platform_driver(rotary_encoder_driver);
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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>, Johan Hovold");
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MODULE_LICENSE("GPL v2");
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