drivers/hid/hid-axff.c

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

File Facts

System
Linux kernel
Corpus path
drivers/hid/hid-axff.c
Extension
.c
Size
4327 bytes
Lines
194
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 axff_device {
	struct hid_report *report;
};

static int axff_play(struct input_dev *dev, void *data, struct ff_effect *effect)
{
	struct hid_device *hid = input_get_drvdata(dev);
	struct axff_device *axff = data;
	struct hid_report *report = axff->report;
	int field_count = 0;
	int left, right;
	int i, j;

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

	dbg_hid("called with 0x%04x 0x%04x", left, right);

	left = left * 0xff / 0xffff;
	right = right * 0xff / 0xffff;

	for (i = 0; i < report->maxfield; i++) {
		for (j = 0; j < report->field[i]->report_count; j++) {
			report->field[i]->value[j] =
				field_count % 2 ? right : left;
			field_count++;
		}
	}

	dbg_hid("running with 0x%02x 0x%02x", left, right);
	hid_hw_request(hid, axff->report, HID_REQ_SET_REPORT);

	return 0;
}

static int axff_init(struct hid_device *hid)
{
	struct axff_device *axff;
	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 field_count = 0;
	int i, j;
	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);
	for (i = 0; i < report->maxfield; i++) {
		for (j = 0; j < report->field[i]->report_count; j++) {
			report->field[i]->value[j] = 0x00;
			field_count++;
		}
	}

	if (field_count < 4 && hid->product != 0xf705) {
		hid_err(hid, "not enough fields in the report: %d\n",
			field_count);
		return -ENODEV;
	}

	axff = kzalloc_obj(struct axff_device);
	if (!axff)
		return -ENOMEM;

	set_bit(FF_RUMBLE, dev->ffbit);

	error = input_ff_create_memless(dev, axff, axff_play);
	if (error)
		goto err_free_mem;

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

	hid_info(hid, "Force Feedback for ACRUX game controllers by Sergei Kolzun <x0r@dv-life.ru>\n");

	return 0;

err_free_mem:

Annotation

Implementation Notes