drivers/hid/hid-google-stadiaff.c

Source file repositories/reference/linux-study-clean/drivers/hid/hid-google-stadiaff.c

File Facts

System
Linux kernel
Corpus path
drivers/hid/hid-google-stadiaff.c
Extension
.c
Size
3798 bytes
Lines
160
Domain
Driver Families
Bucket
drivers/hid
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 stadiaff_device {
	struct hid_device *hid;
	struct hid_report *report;
	spinlock_t lock;
	bool removed;
	uint16_t strong_magnitude;
	uint16_t weak_magnitude;
	struct work_struct work;
};

static void stadiaff_work(struct work_struct *work)
{
	struct stadiaff_device *stadiaff =
		container_of(work, struct stadiaff_device, work);
	struct hid_field *rumble_field = stadiaff->report->field[0];
	unsigned long flags;

	spin_lock_irqsave(&stadiaff->lock, flags);
	rumble_field->value[0] = stadiaff->strong_magnitude;
	rumble_field->value[1] = stadiaff->weak_magnitude;
	spin_unlock_irqrestore(&stadiaff->lock, flags);

	hid_hw_request(stadiaff->hid, stadiaff->report, HID_REQ_SET_REPORT);
}

static int stadiaff_play(struct input_dev *dev, void *data,
			 struct ff_effect *effect)
{
	struct hid_device *hid = input_get_drvdata(dev);
	struct stadiaff_device *stadiaff = hid_get_drvdata(hid);
	unsigned long flags;

	spin_lock_irqsave(&stadiaff->lock, flags);
	if (!stadiaff->removed) {
		stadiaff->strong_magnitude = effect->u.rumble.strong_magnitude;
		stadiaff->weak_magnitude = effect->u.rumble.weak_magnitude;
		schedule_work(&stadiaff->work);
	}
	spin_unlock_irqrestore(&stadiaff->lock, flags);

	return 0;
}

static int stadiaff_init(struct hid_device *hid)
{
	struct stadiaff_device *stadiaff;
	struct hid_report *report;
	struct hid_input *hidinput;
	struct input_dev *dev;
	int error;

	if (list_empty(&hid->inputs)) {
		hid_err(hid, "no inputs found\n");
		return -ENODEV;
	}
	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
	dev = hidinput->input;

	report = hid_validate_values(hid, HID_OUTPUT_REPORT,
				     STADIA_FF_REPORT_ID, 0, 2);
	if (!report)
		return -ENODEV;

	stadiaff = devm_kzalloc(&hid->dev, sizeof(struct stadiaff_device),
				GFP_KERNEL);
	if (!stadiaff)
		return -ENOMEM;

	hid_set_drvdata(hid, stadiaff);

	input_set_capability(dev, EV_FF, FF_RUMBLE);

	error = input_ff_create_memless(dev, NULL, stadiaff_play);
	if (error)
		return error;

	stadiaff->removed = false;
	stadiaff->hid = hid;
	stadiaff->report = report;
	INIT_WORK(&stadiaff->work, stadiaff_work);
	spin_lock_init(&stadiaff->lock);

	hid_info(hid, "Force Feedback for Google Stadia controller\n");

	return 0;
}

static int stadia_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
	int ret;

Annotation

Implementation Notes