drivers/media/rc/img-ir/img-ir-nec.c

Source file repositories/reference/linux-study-clean/drivers/media/rc/img-ir/img-ir-nec.c

File Facts

System
Linux kernel
Corpus path
drivers/media/rc/img-ir/img-ir-nec.c
Extension
.c
Size
4607 bytes
Lines
174
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

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * ImgTec IR Decoder setup for NEC protocol.
 *
 * Copyright 2010-2014 Imagination Technologies Ltd.
 */

#include "img-ir-hw.h"
#include <linux/bitrev.h>
#include <linux/log2.h>

/* Convert NEC data to a scancode */
static int img_ir_nec_scancode(int len, u64 raw, u64 enabled_protocols,
			       struct img_ir_scancode_req *request)
{
	unsigned int addr, addr_inv, data, data_inv;
	/* a repeat code has no data */
	if (!len)
		return IMG_IR_REPEATCODE;
	if (len != 32)
		return -EINVAL;
	/* raw encoding: ddDDaaAA */
	addr     = (raw >>  0) & 0xff;
	addr_inv = (raw >>  8) & 0xff;
	data     = (raw >> 16) & 0xff;
	data_inv = (raw >> 24) & 0xff;
	if ((data_inv ^ data) != 0xff) {
		/* 32-bit NEC (used by Apple and TiVo remotes) */
		/* scan encoding: as transmitted, MSBit = first received bit */
		request->scancode = bitrev8(addr)     << 24 |
				bitrev8(addr_inv) << 16 |
				bitrev8(data)     <<  8 |
				bitrev8(data_inv);
		request->protocol = RC_PROTO_NEC32;
	} else if ((addr_inv ^ addr) != 0xff) {
		/* Extended NEC */
		/* scan encoding: AAaaDD */
		request->scancode = addr     << 16 |
				addr_inv <<  8 |
				data;
		request->protocol = RC_PROTO_NECX;
	} else {
		/* Normal NEC */
		/* scan encoding: AADD */
		request->scancode = addr << 8 |
				data;
		request->protocol = RC_PROTO_NEC;
	}
	return IMG_IR_SCANCODE;
}

/* Convert NEC scancode to NEC data filter */
static int img_ir_nec_filter(const struct rc_scancode_filter *in,
			     struct img_ir_filter *out, u64 protocols)
{
	unsigned int addr, addr_inv, data, data_inv;
	unsigned int addr_m, addr_inv_m, data_m, data_inv_m;

	data       = in->data & 0xff;
	data_m     = in->mask & 0xff;

	protocols &= RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX | RC_PROTO_BIT_NEC32;

	/*
	 * If only one bit is set, we were requested to do an exact
	 * protocol. This should be the case for wakeup filters; for
	 * normal filters, guess the protocol from the scancode.
	 */
	if (!is_power_of_2(protocols)) {
		if ((in->data | in->mask) & 0xff000000)
			protocols = RC_PROTO_BIT_NEC32;
		else if ((in->data | in->mask) & 0x00ff0000)
			protocols = RC_PROTO_BIT_NECX;
		else
			protocols = RC_PROTO_BIT_NEC;
	}

	if (protocols == RC_PROTO_BIT_NEC32) {
		/* 32-bit NEC (used by Apple and TiVo remotes) */
		/* scan encoding: as transmitted, MSBit = first received bit */
		addr       = bitrev8(in->data >> 24);
		addr_m     = bitrev8(in->mask >> 24);
		addr_inv   = bitrev8(in->data >> 16);
		addr_inv_m = bitrev8(in->mask >> 16);
		data       = bitrev8(in->data >>  8);
		data_m     = bitrev8(in->mask >>  8);
		data_inv   = bitrev8(in->data >>  0);
		data_inv_m = bitrev8(in->mask >>  0);
	} else if (protocols == RC_PROTO_BIT_NECX) {
		/* Extended NEC */

Annotation

Implementation Notes