1 files changed, 365 insertions, 0 deletions

diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
new file mode 100644
index 0000000000..e94cab8133
--- /dev/null
+++ b/drivers/input/misc/rotary_encoder.c
@@ -0,0 +1,365 @@
+// 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))
+		return dev_err_probe(dev, PTR_ERR(encoder->gpios), "unable to get gpios\n");
+	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;
+
+	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 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 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 DEFINE_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	= pm_sleep_ptr(&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");