drivers/input/touchscreen/ar1021_i2c.c

Source file repositories/reference/linux-study-clean/drivers/input/touchscreen/ar1021_i2c.c

File Facts

System
Linux kernel
Corpus path
drivers/input/touchscreen/ar1021_i2c.c
Extension
.c
Size
4368 bytes
Lines
193
Domain
Driver Families
Bucket
drivers/input
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct ar1021_i2c {
	struct i2c_client *client;
	struct input_dev *input;
	u8 data[AR1021_TOUCH_PKG_SIZE];
};

static irqreturn_t ar1021_i2c_irq(int irq, void *dev_id)
{
	struct ar1021_i2c *ar1021 = dev_id;
	struct input_dev *input = ar1021->input;
	u8 *data = ar1021->data;
	unsigned int x, y, button;
	int retval;

	retval = i2c_master_recv(ar1021->client,
				 ar1021->data, sizeof(ar1021->data));
	if (retval != sizeof(ar1021->data))
		goto out;

	/* sync bit set ? */
	if (!(data[0] & BIT(7)))
		goto out;

	button = data[0] & BIT(0);
	x = ((data[2] & 0x1f) << 7) | (data[1] & 0x7f);
	y = ((data[4] & 0x1f) << 7) | (data[3] & 0x7f);

	input_report_abs(input, ABS_X, x);
	input_report_abs(input, ABS_Y, y);
	input_report_key(input, BTN_TOUCH, button);
	input_sync(input);

out:
	return IRQ_HANDLED;
}

static int ar1021_i2c_open(struct input_dev *dev)
{
	static const u8 cmd_enable_touch[] = {
		AR1021_CMD,
		0x01, /* number of bytes after this */
		AR1021_CMD_ENABLE_TOUCH
	};
	struct ar1021_i2c *ar1021 = input_get_drvdata(dev);
	struct i2c_client *client = ar1021->client;
	int error;

	error = i2c_master_send(ar1021->client, cmd_enable_touch,
				sizeof(cmd_enable_touch));
	if (error < 0)
		return error;

	enable_irq(client->irq);

	return 0;
}

static void ar1021_i2c_close(struct input_dev *dev)
{
	struct ar1021_i2c *ar1021 = input_get_drvdata(dev);
	struct i2c_client *client = ar1021->client;

	disable_irq(client->irq);
}

static int ar1021_i2c_probe(struct i2c_client *client)
{
	struct ar1021_i2c *ar1021;
	struct input_dev *input;
	int error;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
		dev_err(&client->dev, "i2c_check_functionality error\n");
		return -ENXIO;
	}

	ar1021 = devm_kzalloc(&client->dev, sizeof(*ar1021), GFP_KERNEL);
	if (!ar1021)
		return -ENOMEM;

	input = devm_input_allocate_device(&client->dev);
	if (!input)
		return -ENOMEM;

	ar1021->client = client;
	ar1021->input = input;

	input->name = "ar1021 I2C Touchscreen";
	input->id.bustype = BUS_I2C;
	input->dev.parent = &client->dev;

Annotation

Implementation Notes