media: rc: document and fix rc_validate_scancode()

For some IR protocols, some scancode values not valid, i.e. they're part
of a different protocol variant.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Sean Young 2017-10-09 16:32:41 -04:00 committed by Mauro Carvalho Chehab
parent 49a4b36ada
commit 6b514c4a50

View file

@ -776,21 +776,35 @@ void rc_keydown_notimeout(struct rc_dev *dev, enum rc_proto protocol,
EXPORT_SYMBOL_GPL(rc_keydown_notimeout);
/**
* rc_validate_scancode() - checks that a scancode is valid for a protocol
* rc_validate_scancode() - checks that a scancode is valid for a protocol.
* For nec, it should do the opposite of ir_nec_bytes_to_scancode()
* @proto: protocol
* @scancode: scancode
*/
bool rc_validate_scancode(enum rc_proto proto, u32 scancode)
{
switch (proto) {
/*
* NECX has a 16-bit address; if the lower 8 bits match the upper
* 8 bits inverted, then the address would match regular nec.
*/
case RC_PROTO_NECX:
if ((((scancode >> 16) ^ ~(scancode >> 8)) & 0xff) == 0)
return false;
break;
/*
* NEC32 has a 16 bit address and 16 bit command. If the lower 8 bits
* of the command match the upper 8 bits inverted, then it would
* be either NEC or NECX.
*/
case RC_PROTO_NEC32:
if ((((scancode >> 24) ^ ~(scancode >> 16)) & 0xff) == 0)
if ((((scancode >> 8) ^ ~scancode) & 0xff) == 0)
return false;
break;
/*
* If the customer code (top 32-bit) is 0x800f, it is MCE else it
* is regular mode-6a 32 bit
*/
case RC_PROTO_RC6_MCE:
if ((scancode & 0xffff0000) != 0x800f0000)
return false;