drivers/input/mouse/gpio_mouse.c

Source file repositories/reference/linux-study-clean/drivers/input/mouse/gpio_mouse.c

File Facts

System
Linux kernel
Corpus path
drivers/input/mouse/gpio_mouse.c
Extension
.c
Size
4736 bytes
Lines
171
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 gpio_mouse {
	u32 scan_ms;
	struct gpio_desc *up;
	struct gpio_desc *down;
	struct gpio_desc *left;
	struct gpio_desc *right;
	struct gpio_desc *bleft;
	struct gpio_desc *bmiddle;
	struct gpio_desc *bright;
};

/*
 * Timer function which is run every scan_ms ms when the device is opened.
 * The dev input variable is set to the input_dev pointer.
 */
static void gpio_mouse_scan(struct input_dev *input)
{
	struct gpio_mouse *gpio = input_get_drvdata(input);
	int x, y;

	if (gpio->bleft)
		input_report_key(input, BTN_LEFT,
				 gpiod_get_value(gpio->bleft));
	if (gpio->bmiddle)
		input_report_key(input, BTN_MIDDLE,
				 gpiod_get_value(gpio->bmiddle));
	if (gpio->bright)
		input_report_key(input, BTN_RIGHT,
				 gpiod_get_value(gpio->bright));

	x = gpiod_get_value(gpio->right) - gpiod_get_value(gpio->left);
	y = gpiod_get_value(gpio->down) - gpiod_get_value(gpio->up);

	input_report_rel(input, REL_X, x);
	input_report_rel(input, REL_Y, y);
	input_sync(input);
}

static int gpio_mouse_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct gpio_mouse *gmouse;
	struct input_dev *input;
	int error;

	gmouse = devm_kzalloc(dev, sizeof(*gmouse), GFP_KERNEL);
	if (!gmouse)
		return -ENOMEM;

	/* Assign some default scanning time */
	error = device_property_read_u32(dev, "scan-interval-ms",
					 &gmouse->scan_ms);
	if (error || gmouse->scan_ms == 0) {
		dev_warn(dev, "invalid scan time, set to 50 ms\n");
		gmouse->scan_ms = 50;
	}

	gmouse->up = devm_gpiod_get(dev, "up", GPIOD_IN);
	if (IS_ERR(gmouse->up))
		return PTR_ERR(gmouse->up);
	gmouse->down = devm_gpiod_get(dev, "down", GPIOD_IN);
	if (IS_ERR(gmouse->down))
		return PTR_ERR(gmouse->down);
	gmouse->left = devm_gpiod_get(dev, "left", GPIOD_IN);
	if (IS_ERR(gmouse->left))
		return PTR_ERR(gmouse->left);
	gmouse->right = devm_gpiod_get(dev, "right", GPIOD_IN);
	if (IS_ERR(gmouse->right))
		return PTR_ERR(gmouse->right);

	gmouse->bleft = devm_gpiod_get_optional(dev, "button-left", GPIOD_IN);
	if (IS_ERR(gmouse->bleft))
		return PTR_ERR(gmouse->bleft);
	gmouse->bmiddle = devm_gpiod_get_optional(dev, "button-middle",
						  GPIOD_IN);
	if (IS_ERR(gmouse->bmiddle))
		return PTR_ERR(gmouse->bmiddle);
	gmouse->bright = devm_gpiod_get_optional(dev, "button-right",
						 GPIOD_IN);
	if (IS_ERR(gmouse->bright))
		return PTR_ERR(gmouse->bright);

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

	input->name = pdev->name;
	input->id.bustype = BUS_HOST;

	input_set_drvdata(input, gmouse);

Annotation

Implementation Notes