drivers/media/rc/imon_raw.c

Source file repositories/reference/linux-study-clean/drivers/media/rc/imon_raw.c

File Facts

System
Linux kernel
Corpus path
drivers/media/rc/imon_raw.c
Extension
.c
Size
4717 bytes
Lines
208
Domain
Driver Families
Bucket
drivers/media
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 imon {
	struct device *dev;
	struct urb *ir_urb;
	struct rc_dev *rcdev;
	__be64 *ir_buf;
	char phys[64];
};

/*
 * The first 5 bytes of data represent IR pulse or space. Each bit, starting
 * from highest bit in the first byte, represents 250µs of data. It is 1
 * for space and 0 for pulse.
 *
 * The station sends 10 packets, and the 7th byte will be number 1 to 10, so
 * when we receive 10 we assume all the data has arrived.
 */
static void imon_ir_data(struct imon *imon)
{
	struct ir_raw_event rawir = {};
	u64 data = be64_to_cpup(imon->ir_buf);
	u8 packet_no = data & 0xff;
	int offset = 40;
	int bit;

	if (packet_no == 0xff)
		return;

	dev_dbg(imon->dev, "data: %8ph", imon->ir_buf);

	/*
	 * Only the first 5 bytes contain IR data. Right shift so we move
	 * the IR bits to the lower 40 bits.
	 */
	data >>= 24;

	do {
		/*
		 * Find highest set bit which is less or equal to offset
		 *
		 * offset is the bit above (base 0) where we start looking.
		 *
		 * data & (BIT_ULL(offset) - 1) masks off any unwanted bits,
		 * so we have just bits less than offset.
		 *
		 * fls will tell us the highest bit set plus 1 (or 0 if no
		 * bits are set).
		 */
		rawir.pulse = !rawir.pulse;
		bit = fls64(data & (BIT_ULL(offset) - 1));
		if (bit < offset) {
			dev_dbg(imon->dev, "%s: %d bits",
				rawir.pulse ? "pulse" : "space", offset - bit);
			rawir.duration = (offset - bit) * BIT_DURATION;
			ir_raw_event_store_with_filter(imon->rcdev, &rawir);

			offset = bit;
		}

		data = ~data;
	} while (offset > 0);

	if (packet_no == 0x0a && !imon->rcdev->idle) {
		ir_raw_event_set_idle(imon->rcdev, true);
		ir_raw_event_handle(imon->rcdev);
	}
}

static void imon_ir_rx(struct urb *urb)
{
	struct imon *imon = urb->context;
	int ret;

	switch (urb->status) {
	case 0:
		imon_ir_data(imon);
		break;
	case -ECONNRESET:
	case -ENOENT:
	case -ESHUTDOWN:
		usb_unlink_urb(urb);
		return;
	case -EPIPE:
	default:
		dev_dbg(imon->dev, "error: urb status = %d", urb->status);
		break;
	}

	ret = usb_submit_urb(urb, GFP_ATOMIC);
	if (ret && ret != -ENODEV)
		dev_warn(imon->dev, "failed to resubmit urb: %d", ret);

Annotation

Implementation Notes