1 files changed, 336 insertions, 0 deletions
diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
new file mode 100644
index 000000000..f27f81ee8
--- /dev/null
+++ b/drivers/input/misc/rotary_encoder.c
@@ -0,0 +1,336 @@
+/*
+ * 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/rotary-encoder.txt for more information
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#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.h>
+#include <linux/rotary_encoder.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+
+#define DRV_NAME "rotary-encoder"
+
+struct rotary_encoder {
+	struct input_dev *input;
+	const struct rotary_encoder_platform_data *pdata;
+
+	unsigned int axis;
+	unsigned int pos;
+
+	unsigned int irq_a;
+	unsigned int irq_b;
+
+	bool armed;
+	unsigned char dir;	/* 0 - clockwise, 1 - CCW */
+
+	char last_stable;
+};
+
+static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
+{
+	int a = !!gpio_get_value(pdata->gpio_a);
+	int b = !!gpio_get_value(pdata->gpio_b);
+
+	a ^= pdata->inverted_a;
+	b ^= pdata->inverted_b;
+
+	return ((a << 1) | b);
+}
+
+static void rotary_encoder_report_event(struct rotary_encoder *encoder)
+{
+	const struct rotary_encoder_platform_data *pdata = encoder->pdata;
+
+	if (pdata->relative_axis) {
+		input_report_rel(encoder->input,
+				 pdata->axis, encoder->dir ? -1 : 1);
+	} else {
+		unsigned int pos = encoder->pos;
+
+		if (encoder->dir) {
+			/* turning counter-clockwise */
+			if (pdata->rollover)
+				pos += pdata->steps;
+			if (pos)
+				pos--;
+		} else {
+			/* turning clockwise */
+			if (pdata->rollover || pos < pdata->steps)
+				pos++;
+		}
+
+		if (pdata->rollover)
+			pos %= pdata->steps;
+
+		encoder->pos = pos;
+		input_report_abs(encoder->input, pdata->axis, encoder->pos);
+	}
+
+	input_sync(encoder->input);
+}
+
+static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
+{
+	struct rotary_encoder *encoder = dev_id;
+	int state;
+
+	state = rotary_encoder_get_state(encoder->pdata);
+
+	switch (state) {
+	case 0x0:
+		if (encoder->armed) {
+			rotary_encoder_report_event(encoder);
+			encoder->armed = false;
+		}
+		break;
+
+	case 0x1:
+	case 0x2:
+		if (encoder->armed)
+			encoder->dir = state - 1;
+		break;
+
+	case 0x3:
+		encoder->armed = true;
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
+{
+	struct rotary_encoder *encoder = dev_id;
+	int state;
+
+	state = rotary_encoder_get_state(encoder->pdata);
+
+	switch (state) {
+	case 0x00:
+	case 0x03:
+		if (state != encoder->last_stable) {
+			rotary_encoder_report_event(encoder);
+			encoder->last_stable = state;
+		}
+		break;
+
+	case 0x01:
+	case 0x02:
+		encoder->dir = (encoder->last_stable + state) & 0x01;
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id rotary_encoder_of_match[] = {
+	{ .compatible = "rotary-encoder", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
+
+static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
+{
+	const struct of_device_id *of_id =
+				of_match_device(rotary_encoder_of_match, dev);
+	struct device_node *np = dev->of_node;
+	struct rotary_encoder_platform_data *pdata;
+	enum of_gpio_flags flags;
+
+	if (!of_id || !np)
+		return NULL;
+
+	pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
+			GFP_KERNEL);
+	if (!pdata)
+		return ERR_PTR(-ENOMEM);
+
+	of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
+	of_property_read_u32(np, "linux,axis", &pdata->axis);
+
+	pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
+	pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
+
+	pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
+	pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
+
+	pdata->relative_axis = !!of_get_property(np,
+					"rotary-encoder,relative-axis", NULL);
+	pdata->rollover = !!of_get_property(np,
+					"rotary-encoder,rollover", NULL);
+	pdata->half_period = !!of_get_property(np,
+					"rotary-encoder,half-period", NULL);
+
+	return pdata;
+}
+#else
+static inline struct rotary_encoder_platform_data *
+rotary_encoder_parse_dt(struct device *dev)
+{
+	return NULL;
+}
+#endif
+
+static int rotary_encoder_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
+	struct rotary_encoder *encoder;
+	struct input_dev *input;
+	irq_handler_t handler;
+	int err;
+
+	if (!pdata) {
+		pdata = rotary_encoder_parse_dt(dev);
+		if (IS_ERR(pdata))
+			return PTR_ERR(pdata);
+
+		if (!pdata) {
+			dev_err(dev, "missing platform data\n");
+			return -EINVAL;
+		}
+	}
+
+	encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
+	input = input_allocate_device();
+	if (!encoder || !input) {
+		err = -ENOMEM;
+		goto exit_free_mem;
+	}
+
+	encoder->input = input;
+	encoder->pdata = pdata;
+
+	input->name = pdev->name;
+	input->id.bustype = BUS_HOST;
+	input->dev.parent = dev;
+
+	if (pdata->relative_axis) {
+		input->evbit[0] = BIT_MASK(EV_REL);
+		input->relbit[0] = BIT_MASK(pdata->axis);
+	} else {
+		input->evbit[0] = BIT_MASK(EV_ABS);
+		input_set_abs_params(encoder->input,
+				     pdata->axis, 0, pdata->steps, 0, 1);
+	}
+
+	/* request the GPIOs */
+	err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
+	if (err) {
+		dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
+		goto exit_free_mem;
+	}
+
+	err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
+	if (err) {
+		dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
+		goto exit_free_gpio_a;
+	}
+
+	encoder->irq_a = gpio_to_irq(pdata->gpio_a);
+	encoder->irq_b = gpio_to_irq(pdata->gpio_b);
+
+	/* request the IRQs */
+	if (pdata->half_period) {
+		handler = &rotary_encoder_half_period_irq;
+		encoder->last_stable = rotary_encoder_get_state(pdata);
+	} else {
+		handler = &rotary_encoder_irq;
+	}
+
+	err = request_irq(encoder->irq_a, handler,
+			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+			  DRV_NAME, encoder);
+	if (err) {
+		dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
+		goto exit_free_gpio_b;
+	}
+
+	err = request_irq(encoder->irq_b, handler,
+			  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+			  DRV_NAME, encoder);
+	if (err) {
+		dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
+		goto exit_free_irq_a;
+	}
+
+	err = input_register_device(input);
+	if (err) {
+		dev_err(dev, "failed to register input device\n");
+		goto exit_free_irq_b;
+	}
+
+	platform_set_drvdata(pdev, encoder);
+
+	return 0;
+
+exit_free_irq_b:
+	free_irq(encoder->irq_b, encoder);
+exit_free_irq_a:
+	free_irq(encoder->irq_a, encoder);
+exit_free_gpio_b:
+	gpio_free(pdata->gpio_b);
+exit_free_gpio_a:
+	gpio_free(pdata->gpio_a);
+exit_free_mem:
+	input_free_device(input);
+	kfree(encoder);
+	if (!dev_get_platdata(&pdev->dev))
+		kfree(pdata);
+
+	return err;
+}
+
+static int rotary_encoder_remove(struct platform_device *pdev)
+{
+	struct rotary_encoder *encoder = platform_get_drvdata(pdev);
+	const struct rotary_encoder_platform_data *pdata = encoder->pdata;
+
+	free_irq(encoder->irq_a, encoder);
+	free_irq(encoder->irq_b, encoder);
+	gpio_free(pdata->gpio_a);
+	gpio_free(pdata->gpio_b);
+
+	input_unregister_device(encoder->input);
+	kfree(encoder);
+
+	if (!dev_get_platdata(&pdev->dev))
+		kfree(pdata);
+
+	return 0;
+}
+
+static struct platform_driver rotary_encoder_driver = {
+	.probe		= rotary_encoder_probe,
+	.remove		= rotary_encoder_remove,
+	.driver		= {
+		.name	= DRV_NAME,
+		.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");