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diff --git a/Documentation/userspace-api/media/rc/rc-protos.rst b/Documentation/userspace-api/media/rc/rc-protos.rst new file mode 100644 index 000000000..2e290584a --- /dev/null +++ b/Documentation/userspace-api/media/rc/rc-protos.rst @@ -0,0 +1,454 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _Remote_controllers_Protocols: + +***************************************** +Remote Controller Protocols and Scancodes +***************************************** + +IR is encoded as a series of pulses and spaces, using a protocol. These +protocols can encode e.g. an address (which device should respond) and a +command: what it should do. The values for these are not always consistent +across different devices for a given protocol. + +Therefore out the output of the IR decoder is a scancode; a single u32 +value. Using keymap tables this can be mapped to linux key codes. + +Other things can be encoded too. Some IR protocols encode a toggle bit; this +is to distinguish whether the same button is being held down, or has been +released and pressed again. If has been released and pressed again, the +toggle bit will invert from one IR message to the next. + +Some remotes have a pointer-type device which can used to control the +mouse; some air conditioning systems can have their target temperature +target set in IR. + +The following are the protocols the kernel knows about and also lists +how scancodes are encoded for each protocol. + +rc-5 (RC_PROTO_RC5) +------------------- + +This IR protocol uses manchester encoding to encode 14 bits. There is a +detailed description here https://www.sbprojects.net/knowledge/ir/rc5.php. + +The scancode encoding is *not* consistent with the lirc daemon (lircd) rc5 +protocol, or the manchester BPF decoder. + +.. flat-table:: rc5 bits scancode mapping + :widths: 1 1 2 + + * - rc-5 bit + + - scancode bit + + - description + + * - 1 + + - none + + - Start bit, always set + + * - 1 + + - 6 (inverted) + + - 2nd start bit in rc5, re-used as 6th command bit + + * - 1 + + - none + + - Toggle bit + + * - 5 + + - 8 to 13 + + - Address + + * - 6 + + - 0 to 5 + + - Command + +There is a variant of rc5 called either rc5x or extended rc5 +where there the second stop bit is the 6th commmand bit, but inverted. +This is done so it the scancodes and encoding is compatible with existing +schemes. This bit is stored in bit 6 of the scancode, inverted. This is +done to keep it compatible with plain rc-5 where there are two start bits. + +rc-5-sz (RC_PROTO_RC5_SZ) +------------------------- +This is much like rc-5 but one bit longer. The scancode is encoded +differently. + +.. flat-table:: rc-5-sz bits scancode mapping + :widths: 1 1 2 + + * - rc-5-sz bits + + - scancode bit + + - description + + * - 1 + + - none + + - Start bit, always set + + * - 1 + + - 13 + + - Address bit + + * - 1 + + - none + + - Toggle bit + + * - 6 + + - 6 to 11 + + - Address + + * - 6 + + - 0 to 5 + + - Command + +rc-5x-20 (RC_PROTO_RC5X_20) +--------------------------- + +This rc-5 extended to encoded 20 bits. The is a 3555 microseconds space +after the 8th bit. + +.. flat-table:: rc-5x-20 bits scancode mapping + :widths: 1 1 2 + + * - rc-5-sz bits + + - scancode bit + + - description + + * - 1 + + - none + + - Start bit, always set + + * - 1 + + - 14 + + - Address bit + + * - 1 + + - none + + - Toggle bit + + * - 5 + + - 16 to 20 + + - Address + + * - 6 + + - 8 to 13 + + - Address + + * - 6 + + - 0 to 5 + + - Command + + +jvc (RC_PROTO_JVC) +------------------ + +The jvc protocol is much like nec, without the inverted values. It is +described here https://www.sbprojects.net/knowledge/ir/jvc.php. + +The scancode is a 16 bits value, where the address is the lower 8 bits +and the command the higher 8 bits; this is reversed from IR order. + +sony-12 (RC_PROTO_SONY12) +------------------------- + +The sony protocol is a pulse-width encoding. There are three variants, +which just differ in number of bits and scancode encoding. + +.. flat-table:: sony-12 bits scancode mapping + :widths: 1 1 2 + + * - sony-12 bits + + - scancode bit + + - description + + * - 5 + + - 16 to 20 + + - device + + * - 7 + + - 0 to 6 + + - function + +sony-15 (RC_PROTO_SONY15) +------------------------- + +The sony protocol is a pulse-width encoding. There are three variants, +which just differ in number of bits and scancode encoding. + +.. flat-table:: sony-12 bits scancode mapping + :widths: 1 1 2 + + * - sony-12 bits + + - scancode bit + + - description + + * - 8 + + - 16 to 23 + + - device + + * - 7 + + - 0 to 6 + + - function + +sony-20 (RC_PROTO_SONY20) +------------------------- + +The sony protocol is a pulse-width encoding. There are three variants, +which just differ in number of bits and scancode encoding. + +.. flat-table:: sony-20 bits scancode mapping + :widths: 1 1 2 + + * - sony-20 bits + + - scancode bit + + - description + + * - 5 + + - 16 to 20 + + - device + + * - 7 + + - 0 to 7 + + - device + + * - 8 + + - 8 to 15 + + - extended bits + +nec (RC_PROTO_NEC) +------------------ + +The nec protocol encodes an 8 bit address and an 8 bit command. It is +described here https://www.sbprojects.net/knowledge/ir/nec.php. Note +that the protocol sends least significant bit first. + +As a check, the nec protocol sends the address and command twice; the +second time it is inverted. This is done for verification. + +A plain nec IR message has 16 bits; the high 8 bits are the address +and the low 8 bits are the command. + +nec-x (RC_PROTO_NECX) +--------------------- + +Extended nec has a 16 bit address and a 8 bit command. This is encoded +as a 24 bit value as you would expect, with the lower 8 bits the command +and the upper 16 bits the address. + +nec-32 (RC_PROTO_NEC32) +----------------------- + +nec-32 does not send an inverted address or an inverted command; the +entire message, all 32 bits, are used. + +For this to be decoded correctly, the second 8 bits must not be the +inverted value of the first, and also the last 8 bits must not be the +inverted value of the third 8 bit value. + +The scancode has a somewhat unusual encoding. + +.. flat-table:: nec-32 bits scancode mapping + + * - nec-32 bits + + - scancode bit + + * - First 8 bits + + - 16 to 23 + + * - Second 8 bits + + - 24 to 31 + + * - Third 8 bits + + - 0 to 7 + + * - Fourth 8 bits + + - 8 to 15 + +sanyo (RC_PROTO_SANYO) +---------------------- + +The sanyo protocol is like the nec protocol, but with 13 bits address +rather than 8 bits. Both the address and the command are followed by +their inverted versions, but these are not present in the scancodes. + +Bis 8 to 20 of the scancode is the 13 bits address, and the lower 8 +bits are the command. + +mcir2-kbd (RC_PROTO_MCIR2_KBD) +------------------------------ + +This protocol is generated by the Microsoft MCE keyboard for keyboard +events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded. + +mcir2-mse (RC_PROTO_MCIR2_MSE) +------------------------------ + +This protocol is generated by the Microsoft MCE keyboard for pointer +events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded. + +rc-6-0 (RC_PROTO_RC6_0) +----------------------- + +This is the rc-6 in mode 0. rc-6 is described here +https://www.sbprojects.net/knowledge/ir/rc6.php. +The scancode is the exact 16 bits as in the protocol. There is also a +toggle bit. + +rc-6-6a-20 (RC_PROTO_RC6_6A_20) +------------------------------- + +This is the rc-6 in mode 6a, 20 bits. rc-6 is described here +https://www.sbprojects.net/knowledge/ir/rc6.php. +The scancode is the exact 20 bits +as in the protocol. There is also a toggle bit. + +rc-6-6a-24 (RC_PROTO_RC6_6A_24) +------------------------------- + +This is the rc-6 in mode 6a, 24 bits. rc-6 is described here +https://www.sbprojects.net/knowledge/ir/rc6.php. +The scancode is the exact 24 bits +as in the protocol. There is also a toggle bit. + +rc-6-6a-32 (RC_PROTO_RC6_6A_32) +------------------------------- + +This is the rc-6 in mode 6a, 32 bits. rc-6 is described here +https://www.sbprojects.net/knowledge/ir/rc6.php. +The upper 16 bits are the vendor, +and the lower 16 bits are the vendor-specific bits. This protocol is +for the non-Microsoft MCE variant (vendor != 0x800f). + + +rc-6-mce (RC_PROTO_RC6_MCE) +--------------------------- + +This is the rc-6 in mode 6a, 32 bits. The upper 16 bits are the vendor, +and the lower 16 bits are the vendor-specific bits. This protocol is +for the Microsoft MCE variant (vendor = 0x800f). The toggle bit in the +protocol itself is ignored, and the 16th bit should be takes as the toggle +bit. + +sharp (RC_PROTO_SHARP) +---------------------- + +This is a protocol used by Sharp VCRs, is described here +https://www.sbprojects.net/knowledge/ir/sharp.php. There is a very long +(40ms) space between the normal and inverted values, and some IR receivers +cannot decode this. + +There is a 5 bit address and a 8 bit command. In the scancode the address is +in bits 8 to 12, and the command in bits 0 to 7. + +xmp (RC_PROTO_XMP) +------------------ + +This protocol has several versions and only version 1 is supported. Refer +to the decoder (ir-xmp-decoder.c) to see how it is encoded. + + +cec (RC_PROTO_CEC) +------------------ + +This is not an IR protocol, this is a protocol over CEC. The CEC +infrastructure uses rc-core for handling CEC commands, so that they +can easily be remapped. + +imon (RC_PROTO_IMON) +-------------------- + +This protocol is used by Antec Veris/SoundGraph iMON remotes. + +The protocol +describes both button presses and pointer movements. The protocol encodes +31 bits, and the scancode is simply the 31 bits with the top bit always 0. + +rc-mm-12 (RC_PROTO_RCMM12) +-------------------------- + +The rc-mm protocol is described here +https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply +the 12 bits. + +rc-mm-24 (RC_PROTO_RCMM24) +-------------------------- + +The rc-mm protocol is described here +https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply +the 24 bits. + +rc-mm-32 (RC_PROTO_RCMM32) +-------------------------- + +The rc-mm protocol is described here +https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply +the 32 bits. + +xbox-dvd (RC_PROTO_XBOX_DVD) +---------------------------- + +This protocol is used by XBox DVD Remote, which was made for the original +XBox. There is no in-kernel decoder or encoder for this protocol. The usb +device decodes the protocol. There is a BPF decoder available in v4l-utils. |