drivers/input/joystick/sensehat-joystick.c

Source file repositories/reference/linux-study-clean/drivers/input/joystick/sensehat-joystick.c

File Facts

System
Linux kernel
Corpus path
drivers/input/joystick/sensehat-joystick.c
Extension
.c
Size
3758 bytes
Lines
136
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 sensehat_joystick {
	struct platform_device *pdev;
	struct input_dev *keys_dev;
	unsigned long prev_states;
	struct regmap *regmap;
};

static const unsigned int keymap[] = {
	BTN_DPAD_DOWN, BTN_DPAD_RIGHT, BTN_DPAD_UP, BTN_SELECT, BTN_DPAD_LEFT,
};

static irqreturn_t sensehat_joystick_report(int irq, void *cookie)
{
	struct sensehat_joystick *sensehat_joystick = cookie;
	unsigned long curr_states, changes;
	unsigned int keys;
	int error;
	int i;

	error = regmap_read(sensehat_joystick->regmap, JOYSTICK_SMB_REG, &keys);
	if (error < 0) {
		dev_err(&sensehat_joystick->pdev->dev,
			"Failed to read joystick state: %d", error);
		return IRQ_NONE;
	}
	curr_states = keys;
	bitmap_xor(&changes, &curr_states, &sensehat_joystick->prev_states,
		   ARRAY_SIZE(keymap));

	for_each_set_bit(i, &changes, ARRAY_SIZE(keymap))
		input_report_key(sensehat_joystick->keys_dev, keymap[i],
				 curr_states & BIT(i));

	input_sync(sensehat_joystick->keys_dev);
	sensehat_joystick->prev_states = keys;
	return IRQ_HANDLED;
}

static int sensehat_joystick_probe(struct platform_device *pdev)
{
	struct sensehat_joystick *sensehat_joystick;
	int error, i, irq;

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

	sensehat_joystick->pdev = pdev;

	sensehat_joystick->regmap = dev_get_regmap(pdev->dev.parent, NULL);
	if (!sensehat_joystick->regmap) {
		dev_err(&pdev->dev, "unable to get sensehat regmap");
		return -ENODEV;
	}

	sensehat_joystick->keys_dev = devm_input_allocate_device(&pdev->dev);
	if (!sensehat_joystick->keys_dev) {
		dev_err(&pdev->dev, "Could not allocate input device");
		return -ENOMEM;
	}

	sensehat_joystick->keys_dev->name = "Raspberry Pi Sense HAT Joystick";
	sensehat_joystick->keys_dev->phys = "sensehat-joystick/input0";
	sensehat_joystick->keys_dev->id.bustype = BUS_I2C;

	__set_bit(EV_KEY, sensehat_joystick->keys_dev->evbit);
	__set_bit(EV_REP, sensehat_joystick->keys_dev->evbit);
	for (i = 0; i < ARRAY_SIZE(keymap); i++)
		__set_bit(keymap[i], sensehat_joystick->keys_dev->keybit);

	error = input_register_device(sensehat_joystick->keys_dev);
	if (error) {
		dev_err(&pdev->dev, "Could not register input device");
		return error;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return irq;

	error = devm_request_threaded_irq(&pdev->dev, irq,
					  NULL, sensehat_joystick_report,
					  IRQF_ONESHOT, "keys",
					  sensehat_joystick);
	if (error) {
		dev_err(&pdev->dev, "IRQ request failed");
		return error;
	}

Annotation

Implementation Notes