Add basic structure of evdev to send messages.

linux_driver/ai2c.h

@@ -24,6 +24,7 @@ typedef struct arduino_i2c_driver_data_s  {
 	struct list_head driver_list;
 	struct work_struct intr_upper_work;
 	struct i2c_client *client;
+	struct input_dev *indev;
 	int irq_num;
 	int irq_pin;
 	int irq_count;

linux_driver/arduino_i2c.c

@@ -27,6 +27,7 @@
 
 #include <linux/gpio.h>
 #include <linux/i2c.h>
+#include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
@@ -58,6 +59,11 @@ ai2c_intr(struct work_struct *work) {
 	dev_info(&drv_info->client->dev, "ai2c_intr:  entered\n");
 
 	i2c_smbus_write_byte_data(drv_info->client, 50, 48);
+	input_report_key(drv_info->indev, BTN_0, 1);
+	input_sync(drv_info->indev);
+	input_report_key(drv_info->indev, BTN_0, 0);
+	input_sync(drv_info->indev);
+
 	return;
 }
 
@@ -118,10 +124,34 @@ ai2c_probe(struct i2c_client *client, const struct i2c_device_id *id) {
 	flags |= IRQF_TRIGGER_FALLING;
 	ret = request_irq(drv_info->irq_num, ai2c_intr_lower, flags, "ai2c_keyboard", drv_info);
 	if (ret < 0) {
-		dev_err(&client->dev, "ai2c:  request_irq failed:  error %d\n", ret);
+		dev_err(&client->dev, "ai2c:  request_irq failed:  error %d", ret);
 		goto out_cleanup;
 	}
 
+	drv_info->indev = devm_input_allocate_device(&client->dev);
+	if (!drv_info->indev) {
+		ret = -ENOMEM;
+		dev_err(&client->dev, "ai2c:  unable to allocate input device");
+			goto out_cleanirq;
+	}
+
+	drv_info->indev->name = "arduino_i2c";
+	drv_info->indev->phys = "arduino_i2c/input0";
+	drv_info->indev->dev.parent = &client->dev;
+	drv_info->indev->id.bustype = BUS_I2C;
+	drv_info->indev->id.vendor = 0x4242;
+	drv_info->indev->id.product = 0x4242;
+	drv_info->indev->id.version = 0x0001;
+	drv_info->indev->keycodesize = sizeof(unsigned short);
+	drv_info->indev->keycodemax = BTN_0 + 1;
+	drv_info->indev->evbit[0] = BIT_MASK(EV_KEY);
+	drv_info->indev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0);
+	ret = input_register_device(drv_info->indev);
+	if (ret) {
+		dev_err(&client->dev, "ai2c:  unable to register input device: %d", ret);
+		goto out_cleanindev;
+	}
+
 	irq_set_irq_type(drv_info->irq_num, IRQ_TYPE_EDGE_FALLING);
 
 	drv_info->client = client;
@@ -136,6 +166,10 @@ ai2c_probe(struct i2c_client *client, const struct i2c_device_id *id) {
 
 	return 0;
 
+out_cleanindev:
+	input_free_device(drv_info->indev);
+out_cleanirq:
+	free_irq(drv_info->irq_num, drv_info);
 out_cleanup:
 	gpio_free(drv_info->irq_num);
 out_dealloc:
@@ -157,6 +191,8 @@ ai2c_remove(struct i2c_client *client) {
 
 	dev_set_drvdata(&drv_info->client->dev, NULL);
 
+	input_unregister_device(drv_info->indev);
+
 	mutex_lock(&driver_list_lock);
 	list_del(&drv_info->driver_list);
 	mutex_unlock(&driver_list_lock);