1 files changed, 140 insertions, 0 deletions
diff --git a/drivers/input/misc/gpio_decoder.c b/drivers/input/misc/gpio_decoder.c
new file mode 100644
index 000000000..145826a1a
--- /dev/null
+++ b/drivers/input/misc/gpio_decoder.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * A generic driver to read multiple gpio lines and translate the
+ * encoded numeric value into an input event.
+ */
+
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+struct gpio_decoder {
+	struct gpio_descs *input_gpios;
+	struct device *dev;
+	u32 axis;
+	u32 last_stable;
+};
+
+static int gpio_decoder_get_gpios_state(struct gpio_decoder *decoder)
+{
+	struct gpio_descs *gpios = decoder->input_gpios;
+	unsigned int ret = 0;
+	int i, val;
+
+	for (i = 0; i < gpios->ndescs; i++) {
+		val = gpiod_get_value_cansleep(gpios->desc[i]);
+		if (val < 0) {
+			dev_err(decoder->dev,
+				"Error reading gpio %d: %d\n",
+				desc_to_gpio(gpios->desc[i]), val);
+			return val;
+		}
+
+		val = !!val;
+		ret = (ret << 1) | val;
+	}
+
+	return ret;
+}
+
+static void gpio_decoder_poll_gpios(struct input_dev *input)
+{
+	struct gpio_decoder *decoder = input_get_drvdata(input);
+	int state;
+
+	state = gpio_decoder_get_gpios_state(decoder);
+	if (state >= 0 && state != decoder->last_stable) {
+		input_report_abs(input, decoder->axis, state);
+		input_sync(input);
+		decoder->last_stable = state;
+	}
+}
+
+static int gpio_decoder_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_decoder *decoder;
+	struct input_dev *input;
+	u32  max;
+	int err;
+
+	decoder = devm_kzalloc(dev, sizeof(*decoder), GFP_KERNEL);
+	if (!decoder)
+		return -ENOMEM;
+
+	decoder->dev = dev;
+	device_property_read_u32(dev, "linux,axis", &decoder->axis);
+
+	decoder->input_gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
+	if (IS_ERR(decoder->input_gpios)) {
+		dev_err(dev, "unable to acquire input gpios\n");
+		return PTR_ERR(decoder->input_gpios);
+	}
+
+	if (decoder->input_gpios->ndescs < 2) {
+		dev_err(dev, "not enough gpios found\n");
+		return -EINVAL;
+	}
+
+	if (device_property_read_u32(dev, "decoder-max-value", &max))
+		max = (1U << decoder->input_gpios->ndescs) - 1;
+
+	input = devm_input_allocate_device(dev);
+	if (!input)
+		return -ENOMEM;
+
+	input_set_drvdata(input, decoder);
+
+	input->name = pdev->name;
+	input->id.bustype = BUS_HOST;
+	input_set_abs_params(input, decoder->axis, 0, max, 0, 0);
+
+	err = input_setup_polling(input, gpio_decoder_poll_gpios);
+	if (err) {
+		dev_err(dev, "failed to set up polling\n");
+		return err;
+	}
+
+	err = input_register_device(input);
+	if (err) {
+		dev_err(dev, "failed to register input device\n");
+		return err;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id gpio_decoder_of_match[] = {
+	{ .compatible = "gpio-decoder", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, gpio_decoder_of_match);
+#endif
+
+static struct platform_driver gpio_decoder_driver = {
+	.probe		= gpio_decoder_probe,
+	.driver		= {
+		.name	= "gpio-decoder",
+		.of_match_table = of_match_ptr(gpio_decoder_of_match),
+	}
+};
+module_platform_driver(gpio_decoder_driver);
+
+MODULE_DESCRIPTION("GPIO decoder input driver");
+MODULE_AUTHOR("Vignesh R <vigneshr@ti.com>");
+MODULE_LICENSE("GPL v2");