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path: root/drivers/input/misc/gpio_decoder.c
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Diffstat (limited to 'drivers/input/misc/gpio_decoder.c')
-rw-r--r--drivers/input/misc/gpio_decoder.c132
1 files changed, 132 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..ee668eba3
--- /dev/null
+++ b/drivers/input/misc/gpio_decoder.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * 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");