drivers/hid/hid-dr.c

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

File Facts

System
Linux kernel
Corpus path
drivers/hid/hid-dr.c
Extension
.c
Size
9419 bytes
Lines
321
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 drff_device {
	struct hid_report *report;
};

static int drff_play(struct input_dev *dev, void *data,
				 struct ff_effect *effect)
{
	struct hid_device *hid = input_get_drvdata(dev);
	struct drff_device *drff = data;
	int strong, weak;

	strong = effect->u.rumble.strong_magnitude;
	weak = effect->u.rumble.weak_magnitude;

	dbg_hid("called with 0x%04x 0x%04x", strong, weak);

	if (strong || weak) {
		strong = strong * 0xff / 0xffff;
		weak = weak * 0xff / 0xffff;

		/* While reverse engineering this device, I found that when
		   this value is set, it causes the strong rumble to function
		   at a near maximum speed, so we'll bypass it. */
		if (weak == 0x0a)
			weak = 0x0b;

		drff->report->field[0]->value[0] = 0x51;
		drff->report->field[0]->value[1] = 0x00;
		drff->report->field[0]->value[2] = weak;
		drff->report->field[0]->value[4] = strong;
		hid_hw_request(hid, drff->report, HID_REQ_SET_REPORT);

		drff->report->field[0]->value[0] = 0xfa;
		drff->report->field[0]->value[1] = 0xfe;
	} else {
		drff->report->field[0]->value[0] = 0xf3;
		drff->report->field[0]->value[1] = 0x00;
	}

	drff->report->field[0]->value[2] = 0x00;
	drff->report->field[0]->value[4] = 0x00;
	dbg_hid("running with 0x%02x 0x%02x", strong, weak);
	hid_hw_request(hid, drff->report, HID_REQ_SET_REPORT);

	return 0;
}

static int drff_init(struct hid_device *hid)
{
	struct drff_device *drff;
	struct hid_report *report;
	struct hid_input *hidinput;
	struct list_head *report_list =
			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
	struct input_dev *dev;
	int error;

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

	if (list_empty(report_list)) {
		hid_err(hid, "no output reports found\n");
		return -ENODEV;
	}

	report = list_first_entry(report_list, struct hid_report, list);
	if (report->maxfield < 1) {
		hid_err(hid, "no fields in the report\n");
		return -ENODEV;
	}

	if (report->field[0]->report_count < 7) {
		hid_err(hid, "not enough values in the field\n");
		return -ENODEV;
	}

	drff = kzalloc_obj(struct drff_device);
	if (!drff)
		return -ENOMEM;

	set_bit(FF_RUMBLE, dev->ffbit);

	error = input_ff_create_memless(dev, drff, drff_play);
	if (error) {
		kfree(drff);
		return error;

Annotation

Implementation Notes