drivers/hid/hid-betopff.c

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

File Facts

System
Linux kernel
Corpus path
drivers/hid/hid-betopff.c
Extension
.c
Size
4013 bytes
Lines
167
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 betopff_device {
	struct hid_report *report;
};

static int hid_betopff_play(struct input_dev *dev, void *data,
			 struct ff_effect *effect)
{
	struct hid_device *hid = input_get_drvdata(dev);
	struct betopff_device *betopff = data;
	__u16 left, right;

	left = effect->u.rumble.strong_magnitude;
	right = effect->u.rumble.weak_magnitude;

	betopff->report->field[2]->value[0] = left / 256;
	betopff->report->field[3]->value[0] = right / 256;

	hid_hw_request(hid, betopff->report, HID_REQ_SET_REPORT);

	return 0;
}

static int betopff_init(struct hid_device *hid)
{
	struct betopff_device *betopff;
	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;
	int i, j;

	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);
	/*
	 * Actually there are 4 fields for 4 Bytes as below:
	 * -----------------------------------------
	 * Byte0  Byte1  Byte2	  Byte3
	 * 0x00   0x00   left_motor right_motor
	 * -----------------------------------------
	 * Do init them with default value.
	 */
	if (report->maxfield < 4) {
		hid_err(hid, "not enough fields in the report: %d\n",
				report->maxfield);
		return -ENODEV;
	}
	for (i = 0; i < report->maxfield; i++) {
		if (report->field[i]->report_count < 1) {
			hid_err(hid, "no values in the field\n");
			return -ENODEV;
		}
		for (j = 0; j < report->field[i]->report_count; j++) {
			report->field[i]->value[j] = 0x00;
		}
	}

	betopff = kzalloc_obj(*betopff);
	if (!betopff)
		return -ENOMEM;

	set_bit(FF_RUMBLE, dev->ffbit);

	error = input_ff_create_memless(dev, betopff, hid_betopff_play);
	if (error) {
		kfree(betopff);
		return error;
	}

	betopff->report = report;
	hid_hw_request(hid, betopff->report, HID_REQ_SET_REPORT);

	hid_info(hid, "Force feedback for betop devices by huangbo <huangbobupt@163.com>\n");

	return 0;
}

Annotation

Implementation Notes