// SPDX-License-Identifier: GPL-2.0-only
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/*
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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/devices/rotary-encoder.rst for more information
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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/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/consumer.h>
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#include <linux/slab.h>
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#include <linux/of.h>
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#include <linux/pm.h>
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#include <linux/property.h>
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#define DRV_NAME "rotary-encoder"
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enum rotary_encoder_encoding {
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ROTENC_GRAY,
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ROTENC_BINARY,
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};
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struct rotary_encoder {
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struct input_dev *input;
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struct mutex access_mutex;
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u32 steps;
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u32 axis;
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bool relative_axis;
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bool rollover;
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enum rotary_encoder_encoding encoding;
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unsigned int pos;
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struct gpio_descs *gpios;
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unsigned int *irq;
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bool armed;
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signed char dir; /* 1 - clockwise, -1 - CCW */
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unsigned int last_stable;
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};
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static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
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{
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int i;
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unsigned int ret = 0;
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for (i = 0; i < encoder->gpios->ndescs; ++i) {
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int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);
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/* convert from gray encoding to normal */
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if (encoder->encoding == ROTENC_GRAY && ret & 1)
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val = !val;
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ret = ret << 1 | val;
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}
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return ret & 3;
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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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if (encoder->relative_axis) {
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input_report_rel(encoder->input,
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encoder->axis, encoder->dir);
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} else {
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unsigned int pos = encoder->pos;
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if (encoder->dir < 0) {
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/* turning counter-clockwise */
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if (encoder->rollover)
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pos += encoder->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 (encoder->rollover || pos < encoder->steps)
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pos++;
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}
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if (encoder->rollover)
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pos %= encoder->steps;
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encoder->pos = pos;
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input_report_abs(encoder->input, encoder->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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unsigned int state;
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mutex_lock(&encoder->access_mutex);
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state = rotary_encoder_get_state(encoder);
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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 0x3:
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if (encoder->armed)
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encoder->dir = 2 - state;
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break;
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case 0x2:
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encoder->armed = true;
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break;
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}
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mutex_unlock(&encoder->access_mutex);
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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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unsigned int state;
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mutex_lock(&encoder->access_mutex);
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state = rotary_encoder_get_state(encoder);
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if (state & 1) {
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encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
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} else {
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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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}
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mutex_unlock(&encoder->access_mutex);
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return IRQ_HANDLED;
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}
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static irqreturn_t rotary_encoder_quarter_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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unsigned int state;
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mutex_lock(&encoder->access_mutex);
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state = rotary_encoder_get_state(encoder);
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if ((encoder->last_stable + 1) % 4 == state)
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encoder->dir = 1;
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else if (encoder->last_stable == (state + 1) % 4)
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encoder->dir = -1;
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else
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goto out;
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rotary_encoder_report_event(encoder);
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out:
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encoder->last_stable = state;
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mutex_unlock(&encoder->access_mutex);
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return IRQ_HANDLED;
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}
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static int rotary_encoder_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->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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u32 steps_per_period;
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unsigned int i;
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int err;
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encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
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if (!encoder)
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return -ENOMEM;
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mutex_init(&encoder->access_mutex);
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device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);
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err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
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&steps_per_period);
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if (err) {
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/*
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* The 'half-period' property has been deprecated, you must
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* use 'steps-per-period' and set an appropriate value, but
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* we still need to parse it to maintain compatibility. If
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* neither property is present we fall back to the one step
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* per period behavior.
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*/
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steps_per_period = device_property_read_bool(dev,
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"rotary-encoder,half-period") ? 2 : 1;
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}
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encoder->rollover =
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device_property_read_bool(dev, "rotary-encoder,rollover");
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if (!device_property_present(dev, "rotary-encoder,encoding") ||
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!device_property_match_string(dev, "rotary-encoder,encoding",
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"gray")) {
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dev_info(dev, "gray");
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encoder->encoding = ROTENC_GRAY;
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} else if (!device_property_match_string(dev, "rotary-encoder,encoding",
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"binary")) {
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dev_info(dev, "binary");
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encoder->encoding = ROTENC_BINARY;
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} else {
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dev_err(dev, "unknown encoding setting\n");
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return -EINVAL;
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}
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device_property_read_u32(dev, "linux,axis", &encoder->axis);
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encoder->relative_axis =
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device_property_read_bool(dev, "rotary-encoder,relative-axis");
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encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
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if (IS_ERR(encoder->gpios)) {
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err = PTR_ERR(encoder->gpios);
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if (err != -EPROBE_DEFER)
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dev_err(dev, "unable to get gpios: %d\n", err);
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return err;
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}
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if (encoder->gpios->ndescs < 2) {
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dev_err(dev, "not enough gpios found\n");
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return -EINVAL;
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}
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input = devm_input_allocate_device(dev);
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if (!input)
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return -ENOMEM;
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encoder->input = input;
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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 (encoder->relative_axis)
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input_set_capability(input, EV_REL, encoder->axis);
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else
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input_set_abs_params(input,
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encoder->axis, 0, encoder->steps, 0, 1);
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switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
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case 4:
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handler = &rotary_encoder_quarter_period_irq;
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encoder->last_stable = rotary_encoder_get_state(encoder);
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break;
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case 2:
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handler = &rotary_encoder_half_period_irq;
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encoder->last_stable = rotary_encoder_get_state(encoder);
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break;
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case 1:
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handler = &rotary_encoder_irq;
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break;
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default:
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dev_err(dev, "'%d' is not a valid steps-per-period value\n",
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steps_per_period);
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return -EINVAL;
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}
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encoder->irq =
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devm_kcalloc(dev,
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encoder->gpios->ndescs, sizeof(*encoder->irq),
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GFP_KERNEL);
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if (!encoder->irq)
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return -ENOMEM;
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for (i = 0; i < encoder->gpios->ndescs; ++i) {
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encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
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err = devm_request_threaded_irq(dev, encoder->irq[i],
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NULL, handler,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
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IRQF_ONESHOT,
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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 (gpio#%d)\n",
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encoder->irq[i], i);
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return err;
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}
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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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return err;
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}
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device_init_wakeup(dev,
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device_property_read_bool(dev, "wakeup-source"));
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platform_set_drvdata(pdev, encoder);
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return 0;
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}
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static int __maybe_unused rotary_encoder_suspend(struct device *dev)
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{
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struct rotary_encoder *encoder = dev_get_drvdata(dev);
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unsigned int i;
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if (device_may_wakeup(dev)) {
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for (i = 0; i < encoder->gpios->ndescs; ++i)
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enable_irq_wake(encoder->irq[i]);
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}
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return 0;
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}
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static int __maybe_unused rotary_encoder_resume(struct device *dev)
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{
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struct rotary_encoder *encoder = dev_get_drvdata(dev);
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unsigned int i;
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if (device_may_wakeup(dev)) {
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for (i = 0; i < encoder->gpios->ndescs; ++i)
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disable_irq_wake(encoder->irq[i]);
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}
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return 0;
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}
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static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
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rotary_encoder_suspend, rotary_encoder_resume);
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#ifdef CONFIG_OF
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static const 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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#endif
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static struct platform_driver rotary_encoder_driver = {
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.probe = rotary_encoder_probe,
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.driver = {
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.name = DRV_NAME,
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.pm = &rotary_encoder_pm_ops,
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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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