kscan: input: add input to kscan adapter

Add a driver that listens for input events and reports them on a kscan
API. This allows porting kscan drivers to the input APIs while
maintaining compatibility with the existing kscan based applications.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

drivers/kscan/CMakeLists.txt

@@ -12,5 +12,6 @@ zephyr_library_sources_ifdef(CONFIG_KSCAN_CST816S	kscan_cst816s.c)
 zephyr_library_sources_ifdef(CONFIG_KSCAN_CAP1203	kscan_cap1203.c)
 zephyr_library_sources_ifdef(CONFIG_KSCAN_NPCX		kscan_npcx.c)
 zephyr_library_sources_ifdef(CONFIG_KSCAN_XPT2046	kscan_xpt2046.c)
+zephyr_library_sources_ifdef(CONFIG_KSCAN_INPUT		kscan_input.c)
 
 zephyr_library_sources_ifdef(CONFIG_USERSPACE	    kscan_handlers.c)

drivers/kscan/Kconfig

@@ -20,6 +20,7 @@ source "drivers/kscan/Kconfig.cst816s"
 source "drivers/kscan/Kconfig.cap1203"
 source "drivers/kscan/Kconfig.npcx"
 source "drivers/kscan/Kconfig.xpt2046"
+source "drivers/kscan/Kconfig.input"
 
 module = KSCAN
 module-str = kscan

drivers/kscan/Kconfig.input

@@ -0,0 +1,8 @@
+# Copyright 2023 Google LLC
+# SPDX-License-Identifier: Apache-2.0
+
+config KSCAN_INPUT
+	bool "Input subsystem to kscan adapter driver"
+	default y
+	depends on INPUT
+	depends on DT_HAS_ZEPHYR_KSCAN_INPUT_ENABLED

drivers/kscan/kscan_input.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#define DT_DRV_COMPAT zephyr_kscan_input
+
+#include <zephyr/drivers/kscan.h>
+#include <zephyr/input/input.h>
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(kscan_input, CONFIG_KSCAN_LOG_LEVEL);
+
+struct kscan_input_config {
+	const struct device *input_dev;
+};
+
+struct kscan_input_data {
+	bool enabled;
+	kscan_callback_t callback;
+	int row;
+	int col;
+	bool pressed;
+};
+
+static void kscan_input_cb(const struct device *dev, struct input_event *evt)
+{
+	struct kscan_input_data *data = dev->data;
+
+	switch (evt->code) {
+	case INPUT_ABS_X:
+		data->col = evt->value;
+		break;
+	case INPUT_ABS_Y:
+		data->row = evt->value;
+		break;
+	case INPUT_BTN_TOUCH:
+		data->pressed = evt->value;
+		break;
+	}
+
+	if (evt->sync) {
+		LOG_DBG("input event: %3d %3d %d",
+			data->row, data->col, data->pressed);
+		if (data->callback) {
+			data->callback(dev, data->row, data->col, data->pressed);
+		}
+	}
+}
+
+static int kscan_input_configure(const struct device *dev,
+				      kscan_callback_t callback)
+{
+	struct kscan_input_data *data = dev->data;
+
+	if (!callback) {
+		LOG_ERR("Invalid callback (NULL)");
+		return -EINVAL;
+	}
+
+	data->callback = callback;
+
+	return 0;
+}
+
+static int kscan_input_enable_callback(const struct device *dev)
+{
+	struct kscan_input_data *data = dev->data;
+
+	data->enabled = true;
+
+	return 0;
+}
+
+static int kscan_input_disable_callback(const struct device *dev)
+{
+	struct kscan_input_data *data = dev->data;
+
+	data->enabled = false;
+
+	return 0;
+}
+
+static int kscan_input_init(const struct device *dev)
+{
+	const struct kscan_input_config *cfg = dev->config;
+
+	if (!device_is_ready(cfg->input_dev)) {
+		LOG_ERR("Input device not ready");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static const struct kscan_driver_api kscan_input_driver_api = {
+	.config = kscan_input_configure,
+	.enable_callback = kscan_input_enable_callback,
+	.disable_callback = kscan_input_disable_callback,
+};
+
+#define KSCAN_INPUT_INIT(index) \
+	static void kscan_input_cb_##index(struct input_event *evt)            \
+	{                                                                      \
+		kscan_input_cb(DEVICE_DT_GET(DT_INST(index, DT_DRV_COMPAT)),   \
+			       evt);                                           \
+	}                                                                      \
+	INPUT_LISTENER_CB_DEFINE(DEVICE_DT_GET(DT_INST_PARENT(index)),         \
+				 kscan_input_cb_##index);                      \
+	static const struct kscan_input_config kscan_input_config_##index = {  \
+		.input_dev = DEVICE_DT_GET(DT_INST_PARENT(index)),             \
+	};                                                                     \
+	static struct kscan_input_data kscan_input_data_##index;               \
+	DEVICE_DT_INST_DEFINE(index, kscan_input_init, NULL,                   \
+			      &kscan_input_data_##index,                       \
+			      &kscan_input_config_##index,                     \
+			      POST_KERNEL, CONFIG_KSCAN_INIT_PRIORITY,         \
+			      &kscan_input_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(KSCAN_INPUT_INIT)

dts/bindings/kscan/zephyr,kscan-input.yaml

@@ -0,0 +1,23 @@
+# Copyright 2023 Google LLC
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Input to kscan adapter.
+
+  Allows using an input device with the kscan API. Define as a child node of
+  the input device, for example
+
+  chosen {
+    zephyr,keyboard-scan = &kscan_input;
+  };
+
+  ft5336@38 {
+    ...
+    kscan_input: kscan-input {
+      compatible = "zephyr,kscan-input";
+    };
+  };
+
+compatible: "zephyr,kscan-input"
+
+include: kscan.yaml