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// SPDX-License-Identifier: GPL-2.0-only
/*
* rotary_encoder.c
*
* (c) 2009 Daniel Mack <daniel@caiaq.de>
* Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
*
* state machine code inspired by code from Tim Ruetz
*
* A generic driver for rotary encoders connected to GPIO lines.
* See file:Documentation/input/devices/rotary-encoder.rst for more information
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/property.h>
#define DRV_NAME "rotary-encoder"
enum rotary_encoder_encoding {
ROTENC_GRAY,
ROTENC_BINARY,
};
struct rotary_encoder {
struct input_dev *input;
struct mutex access_mutex;
u32 steps;
u32 axis;
bool relative_axis;
bool rollover;
enum rotary_encoder_encoding encoding;
unsigned int pos;
struct gpio_descs *gpios;
unsigned int *irq;
bool armed;
signed char dir; /* 1 - clockwise, -1 - CCW */
unsigned int last_stable;
};
static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
{
int i;
unsigned int ret = 0;
for (i = 0; i < encoder->gpios->ndescs; ++i) {
int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);
/* convert from gray encoding to normal */
if (encoder->encoding == ROTENC_GRAY && ret & 1)
val = !val;
ret = ret << 1 | val;
}
return ret & 3;
}
static void rotary_encoder_report_event(struct rotary_encoder *encoder)
{
if (encoder->relative_axis) {
input_report_rel(encoder->input,
encoder->axis, encoder->dir);
} else {
unsigned int pos = encoder->pos;
if (encoder->dir < 0) {
/* turning counter-clockwise */
if (encoder->rollover)
pos += encoder->steps;
if (pos)
pos--;
} else {
/* turning clockwise */
if (encoder->rollover || pos < encoder->steps)
pos++;
}
if (encoder->rollover)
pos %= encoder->steps;
encoder->pos = pos;
input_report_abs(encoder->input, encoder->axis, encoder->pos);
}
input_sync(encoder->input);
}
static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
{
struct rotary_encoder *encoder = dev_id;
unsigned int state;
mutex_lock(&encoder->access_mutex);
state = rotary_encoder_get_state(encoder);
switch (state) {
case 0x0:
if (encoder->armed) {
rotary_encoder_report_event(encoder);
encoder->armed = false;
}
break;
case 0x1:
case 0x3:
if (encoder->armed)
encoder->dir = 2 - state;
break;
case 0x2:
encoder->armed = true;
break;
}
mutex_unlock(&encoder->access_mutex);
return IRQ_HANDLED;
}
static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
{
struct rotary_encoder *encoder = dev_id;
unsigned int state;
mutex_lock(&encoder->access_mutex);
state = rotary_encoder_get_state(encoder);
if (state & 1) {
encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
} else {
if (state != encoder->last_stable) {
rotary_encoder_report_event(encoder);
encoder->last_stable = state;
}
}
mutex_unlock(&encoder->access_mutex);
return IRQ_HANDLED;
}
static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
{
struct rotary_encoder *encoder = dev_id;
unsigned int state;
mutex_lock(&encoder->access_mutex);
state = rotary_encoder_get_state(encoder);
if ((encoder->last_stable + 1) % 4 == state)
encoder->dir = 1;
else if (encoder->last_stable == (state + 1) % 4)
encoder->dir = -1;
else
goto out;
rotary_encoder_report_event(encoder);
out:
encoder->last_stable = state;
mutex_unlock(&encoder->access_mutex);
return IRQ_HANDLED;
}
static int rotary_encoder_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rotary_encoder *encoder;
struct input_dev *input;
irq_handler_t handler;
u32 steps_per_period;
unsigned int i;
int err;
encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
if (!encoder)
return -ENOMEM;
mutex_init(&encoder->access_mutex);
device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);
err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
&steps_per_period);
if (err) {
/*
* The 'half-period' property has been deprecated, you must
* use 'steps-per-period' and set an appropriate value, but
* we still need to parse it to maintain compatibility. If
* neither property is present we fall back to the one step
* per period behavior.
*/
steps_per_period = device_property_read_bool(dev,
"rotary-encoder,half-period") ? 2 : 1;
}
encoder->rollover =
device_property_read_bool(dev, "rotary-encoder,rollover");
if (!device_property_present(dev, "rotary-encoder,encoding") ||
!device_property_match_string(dev, "rotary-encoder,encoding",
"gray")) {
dev_info(dev, "gray");
encoder->encoding = ROTENC_GRAY;
} else if (!device_property_match_string(dev, "rotary-encoder,encoding",
"binary")) {
dev_info(dev, "binary");
encoder->encoding = ROTENC_BINARY;
} else {
dev_err(dev, "unknown encoding setting\n");
return -EINVAL;
}
device_property_read_u32(dev, "linux,axis", &encoder->axis);
encoder->relative_axis =
device_property_read_bool(dev, "rotary-encoder,relative-axis");
encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
if (IS_ERR(encoder->gpios)) {
err = PTR_ERR(encoder->gpios);
if (err != -EPROBE_DEFER)
dev_err(dev, "unable to get gpios: %d\n", err);
return err;
}
if (encoder->gpios->ndescs < 2) {
dev_err(dev, "not enough gpios found\n");
return -EINVAL;
}
input = devm_input_allocate_device(dev);
if (!input)
return -ENOMEM;
encoder->input = input;
input->name = pdev->name;
input->id.bustype = BUS_HOST;
input->dev.parent = dev;
if (encoder->relative_axis)
input_set_capability(input, EV_REL, encoder->axis);
else
input_set_abs_params(input,
encoder->axis, 0, encoder->steps, 0, 1);
switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
case 4:
handler = &rotary_encoder_quarter_period_irq;
encoder->last_stable = rotary_encoder_get_state(encoder);
break;
case 2:
handler = &rotary_encoder_half_period_irq;
encoder->last_stable = rotary_encoder_get_state(encoder);
break;
case 1:
handler = &rotary_encoder_irq;
break;
default:
dev_err(dev, "'%d' is not a valid steps-per-period value\n",
steps_per_period);
return -EINVAL;
}
encoder->irq =
devm_kcalloc(dev,
encoder->gpios->ndescs, sizeof(*encoder->irq),
GFP_KERNEL);
if (!encoder->irq)
return -ENOMEM;
for (i = 0; i < encoder->gpios->ndescs; ++i) {
encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
err = devm_request_threaded_irq(dev, encoder->irq[i],
NULL, handler,
IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
IRQF_ONESHOT,
DRV_NAME, encoder);
if (err) {
dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
encoder->irq[i], i);
return err;
}
}
err = input_register_device(input);
if (err) {
dev_err(dev, "failed to register input device\n");
return err;
}
device_init_wakeup(dev,
device_property_read_bool(dev, "wakeup-source"));
platform_set_drvdata(pdev, encoder);
return 0;
}
static int __maybe_unused rotary_encoder_suspend(struct device *dev)
{
struct rotary_encoder *encoder = dev_get_drvdata(dev);
unsigned int i;
if (device_may_wakeup(dev)) {
for (i = 0; i < encoder->gpios->ndescs; ++i)
enable_irq_wake(encoder->irq[i]);
}
return 0;
}
static int __maybe_unused rotary_encoder_resume(struct device *dev)
{
struct rotary_encoder *encoder = dev_get_drvdata(dev);
unsigned int i;
if (device_may_wakeup(dev)) {
for (i = 0; i < encoder->gpios->ndescs; ++i)
disable_irq_wake(encoder->irq[i]);
}
return 0;
}
static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
rotary_encoder_suspend, rotary_encoder_resume);
#ifdef CONFIG_OF
static const struct of_device_id rotary_encoder_of_match[] = {
{ .compatible = "rotary-encoder", },
{ },
};
MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
#endif
static struct platform_driver rotary_encoder_driver = {
.probe = rotary_encoder_probe,
.driver = {
.name = DRV_NAME,
.pm = &rotary_encoder_pm_ops,
.of_match_table = of_match_ptr(rotary_encoder_of_match),
}
};
module_platform_driver(rotary_encoder_driver);
MODULE_ALIAS("platform:" DRV_NAME);
MODULE_DESCRIPTION("GPIO rotary encoder driver");
MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
MODULE_LICENSE("GPL v2");