cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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img-ir-rc6.c (2482B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * ImgTec IR Decoder setup for Philips RC-6 protocol.
      4 *
      5 * Copyright 2012-2014 Imagination Technologies Ltd.
      6 */
      7
      8#include "img-ir-hw.h"
      9
     10/* Convert RC6 data to a scancode */
     11static int img_ir_rc6_scancode(int len, u64 raw, u64 enabled_protocols,
     12				struct img_ir_scancode_req *request)
     13{
     14	unsigned int addr, cmd, mode, trl1, trl2;
     15
     16	/*
     17	 * Due to a side effect of the decoder handling the double length
     18	 * Trailer bit, the header information is a bit scrambled, and the
     19	 * raw data is shifted incorrectly.
     20	 * This workaround effectively recovers the header bits.
     21	 *
     22	 * The Header field should look like this:
     23	 *
     24	 * StartBit ModeBit2 ModeBit1 ModeBit0 TrailerBit
     25	 *
     26	 * But what we get is:
     27	 *
     28	 * ModeBit2 ModeBit1 ModeBit0 TrailerBit1 TrailerBit2
     29	 *
     30	 * The start bit is not important to recover the scancode.
     31	 */
     32
     33	raw	>>= 27;
     34
     35	trl1	= (raw >>  17)	& 0x01;
     36	trl2	= (raw >>  16)	& 0x01;
     37
     38	mode	= (raw >>  18)	& 0x07;
     39	addr	= (raw >>   8)	& 0xff;
     40	cmd	=  raw		& 0xff;
     41
     42	/*
     43	 * Due to the above explained irregularity the trailer bits cannot
     44	 * have the same value.
     45	 */
     46	if (trl1 == trl2)
     47		return -EINVAL;
     48
     49	/* Only mode 0 supported for now */
     50	if (mode)
     51		return -EINVAL;
     52
     53	request->protocol = RC_PROTO_RC6_0;
     54	request->scancode = addr << 8 | cmd;
     55	request->toggle	  = trl2;
     56	return IMG_IR_SCANCODE;
     57}
     58
     59/* Convert RC6 scancode to RC6 data filter */
     60static int img_ir_rc6_filter(const struct rc_scancode_filter *in,
     61				 struct img_ir_filter *out, u64 protocols)
     62{
     63	/* Not supported by the hw. */
     64	return -EINVAL;
     65}
     66
     67/*
     68 * RC-6 decoder
     69 * see http://www.sbprojects.com/knowledge/ir/rc6.php
     70 */
     71struct img_ir_decoder img_ir_rc6 = {
     72	.type		= RC_PROTO_BIT_RC6_0,
     73	.control	= {
     74		.bitorien	= 1,
     75		.code_type	= IMG_IR_CODETYPE_BIPHASE,
     76		.decoden	= 1,
     77		.decodinpol	= 1,
     78	},
     79	/* main timings */
     80	.tolerance	= 20,
     81	/*
     82	 * Due to a quirk in the img-ir decoder, default header values do
     83	 * not work, the values described below were extracted from
     84	 * successful RTL test cases.
     85	 */
     86	.timings	= {
     87		/* leader symbol */
     88		.ldr = {
     89			.pulse	= { 650 },
     90			.space	= { 660 },
     91		},
     92		/* 0 symbol */
     93		.s00 = {
     94			.pulse	= { 370 },
     95			.space	= { 370 },
     96		},
     97		/* 01 symbol */
     98		.s01 = {
     99			.pulse	= { 370 },
    100			.space	= { 370 },
    101		},
    102		/* free time */
    103		.ft  = {
    104			.minlen = 21,
    105			.maxlen = 21,
    106			.ft_min = 2666,	/* 2.666 ms */
    107		},
    108	},
    109
    110	/* scancode logic */
    111	.scancode	= img_ir_rc6_scancode,
    112	.filter		= img_ir_rc6_filter,
    113};