drivers/hid/hid-tmff.c

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

File Facts

System
Linux kernel
Corpus path
drivers/hid/hid-tmff.c
Extension
.c
Size
7166 bytes
Lines
270
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 tmff_device {
	struct hid_report *report;
	struct hid_field *ff_field;
};

/* Changes values from 0 to 0xffff into values from minimum to maximum */
static inline int tmff_scale_u16(unsigned int in, int minimum, int maximum)
{
	int ret;

	ret = (in * (maximum - minimum) / 0xffff) + minimum;
	if (ret < minimum)
		return minimum;
	if (ret > maximum)
		return maximum;
	return ret;
}

/* Changes values from -0x80 to 0x7f into values from minimum to maximum */
static inline int tmff_scale_s8(int in, int minimum, int maximum)
{
	int ret;

	ret = (((in + 0x80) * (maximum - minimum)) / 0xff) + minimum;
	if (ret < minimum)
		return minimum;
	if (ret > maximum)
		return maximum;
	return ret;
}

static int tmff_play(struct input_dev *dev, void *data,
		struct ff_effect *effect)
{
	struct hid_device *hid = input_get_drvdata(dev);
	struct tmff_device *tmff = data;
	struct hid_field *ff_field = tmff->ff_field;
	int x, y;
	int left, right;	/* Rumbling */

	switch (effect->type) {
	case FF_CONSTANT:
		x = tmff_scale_s8(effect->u.ramp.start_level,
					ff_field->logical_minimum,
					ff_field->logical_maximum);
		y = tmff_scale_s8(effect->u.ramp.end_level,
					ff_field->logical_minimum,
					ff_field->logical_maximum);

		dbg_hid("(x, y)=(%04x, %04x)\n", x, y);
		ff_field->value[0] = x;
		ff_field->value[1] = y;
		hid_hw_request(hid, tmff->report, HID_REQ_SET_REPORT);
		break;

	case FF_RUMBLE:
		left = tmff_scale_u16(effect->u.rumble.weak_magnitude,
					ff_field->logical_minimum,
					ff_field->logical_maximum);
		right = tmff_scale_u16(effect->u.rumble.strong_magnitude,
					ff_field->logical_minimum,
					ff_field->logical_maximum);

		/* 2-in-1 strong motor is left */
		if (hid->product == THRUSTMASTER_DEVICE_ID_2_IN_1_DT)
			swap(left, right);

		dbg_hid("(left,right)=(%08x, %08x)\n", left, right);
		ff_field->value[0] = left;
		ff_field->value[1] = right;
		hid_hw_request(hid, tmff->report, HID_REQ_SET_REPORT);
		break;
	}
	return 0;
}

static int tmff_init(struct hid_device *hid, const signed short *ff_bits)
{
	struct tmff_device *tmff;
	struct hid_report *report;
	struct list_head *report_list;
	struct hid_input *hidinput;
	struct input_dev *input_dev;
	int error;
	int i;

	if (list_empty(&hid->inputs)) {
		hid_err(hid, "no inputs found\n");
		return -ENODEV;
	}

Annotation

Implementation Notes