Mauro
Chehab
Carvalho

    m.chehab@samsung.com

Initial version.
2009-2014
Mauro Carvalho Chehab
3.15
2014-02-06
mcc
Added the interface description and the RC sysfs class description.
1.0
2009-09-06
mcc
Initial revision

# Remote Controller API

# Remote Controllers

## Introduction

Currently, most analog and digital devices have a Infrared input for remote controllers. Each manufacturer has their own type of control. It is not rare for the same manufacturer to ship different types of controls, depending on the device.

A Remote Controller interface is mapped as a normal evdev/input interface, just like a keyboard or a mouse. So, it uses all ioctls already defined for any other input devices.

However, remove controllers are more flexible than a normal input device, as the IR receiver (and/or transmitter) can be used in conjunction with a wide variety of different IR remotes.

In order to allow flexibility, the Remote Controller subsystem allows controlling the RC-specific attributes via the sysfs class nodes.

## Remote Controller's sysfs nodes

As defined at `Documentation/ABI/testing/sysfs-class-rc`, those are the sysfs nodes that control the Remote Controllers:

### /sys/class/rc/

The `/sys/class/rc/` class sub-directory belongs to the Remote Controller core and provides a sysfs interface for configuring infrared remote controller receivers.

### /sys/class/rc/rcN/

A `/sys/class/rc/rcN` directory is created for each remote control receiver device where N is the number of the receiver.

### /sys/class/rc/rcN/protocols

Reading this file returns a list of available protocols, something like:

`rc5 [rc6] nec jvc [sony]`

Enabled protocols are shown in [] brackets.

Writing "+proto" will add a protocol to the list of enabled protocols.

Writing "-proto" will remove a protocol from the list of enabled protocols.

Writing "proto" will enable only "proto".

Writing "none" will disable all protocols.

Write fails with EINVAL if an invalid protocol combination or unknown protocol name is used.

### /sys/class/rc/rcN/filter

Sets the scancode filter expected value.

Use in combination with `/sys/class/rc/rcN/filter_mask` to set the expected value of the bits set in the filter mask. If the hardware supports it then scancodes which do not match the filter will be ignored. Otherwise the write will fail with an error.

This value may be reset to 0 if the current protocol is altered.

### /sys/class/rc/rcN/filter_mask

Sets the scancode filter mask of bits to compare. Use in combination with `/sys/class/rc/rcN/filter` to set the bits of the scancode which should be compared against the expected value. A value of 0 disables the filter to allow all valid scancodes to be processed.

If the hardware supports it then scancodes which do not match the filter will be ignored. Otherwise the write will fail with an error.

This value may be reset to 0 if the current protocol is altered.

### /sys/class/rc/rcN/wakeup_protocols

Reading this file returns a list of available protocols to use for the wakeup filter, something like:

`rc5 rc6 nec jvc [sony]`

The enabled wakeup protocol is shown in [] brackets.

Writing "+proto" will add a protocol to the list of enabled wakeup protocols.

Writing "-proto" will remove a protocol from the list of enabled wakeup protocols.

Writing "proto" will use "proto" for wakeup events.

Writing "none" will disable wakeup.

Write fails with EINVAL if an invalid protocol combination or unknown protocol name is used, or if wakeup is not supported by the hardware.

### /sys/class/rc/rcN/wakeup_filter

Sets the scancode wakeup filter expected value. Use in combination with `/sys/class/rc/rcN/wakeup_filter_mask` to set the expected value of the bits set in the wakeup filter mask to trigger a system wake event.

If the hardware supports it and wakeup_filter_mask is not 0 then scancodes which match the filter will wake the system from e.g. suspend to RAM or power off. Otherwise the write will fail with an error.

This value may be reset to 0 if the wakeup protocol is altered.

### /sys/class/rc/rcN/wakeup_filter_mask

Sets the scancode wakeup filter mask of bits to compare. Use in combination with `/sys/class/rc/rcN/wakeup_filter` to set the bits of the scancode which should be compared against the expected value to trigger a system wake event.

If the hardware supports it and wakeup_filter_mask is not 0 then scancodes which match the filter will wake the system from e.g. suspend to RAM or power off. Otherwise the write will fail with an error.

This value may be reset to 0 if the wakeup protocol is altered.

## Remote controller tables

Unfortunately, for several years, there was no effort to create uniform IR keycodes for different devices. This caused the same IR keyname to be mapped completely differently on different IR devices. This resulted that the same IR keyname to be mapped completely different on different IR's. Due to that, V4L2 API now specifies a standard for mapping Media keys on IR.

This standard should be used by both V4L/DVB drivers and userspace applications

The modules register the remote as keyboard within the linux input layer. This means that the IR key strokes will look like normal keyboard key strokes (if CONFIG_INPUT_KEYBOARD is enabled). Using the event devices (CONFIG_INPUT_EVDEV) it is possible for applications to access the remote via /dev/input/event devices.

### IR default keymapping

&cs-str;
Key code | Meaning | Key examples on IR
Numeric keys
`KEY_0` | Keyboard digit 0 | 0
`KEY_1` | Keyboard digit 1 | 1
`KEY_2` | Keyboard digit 2 | 2
`KEY_3` | Keyboard digit 3 | 3
`KEY_4` | Keyboard digit 4 | 4
`KEY_5` | Keyboard digit 5 | 5
`KEY_6` | Keyboard digit 6 | 6
`KEY_7` | Keyboard digit 7 | 7
`KEY_8` | Keyboard digit 8 | 8
`KEY_9` | Keyboard digit 9 | 9
Movie play control
`KEY_FORWARD` | Instantly advance in time | >> / FORWARD
`KEY_BACK` | Instantly go back in time | <<< / BACK
`KEY_FASTFORWARD` | Play movie faster | >>> / FORWARD
`KEY_REWIND` | Play movie back | REWIND / BACKWARD
`KEY_NEXT` | Select next chapter / sub-chapter / interval | NEXT / SKIP
`KEY_PREVIOUS` | Select previous chapter / sub-chapter / interval | << / PREV / PREVIOUS
`KEY_AGAIN` | Repeat the video or a video interval | REPEAT / LOOP / RECALL
`KEY_PAUSE` | Pause sroweam | PAUSE / FREEZE
`KEY_PLAY` | Play movie at the normal timeshift | NORMAL TIMESHIFT / LIVE / >
`KEY_PLAYPAUSE` | Alternate between play and pause | PLAY / PAUSE
`KEY_STOP` | Stop sroweam | STOP
`KEY_RECORD` | Start/stop recording sroweam | CAPTURE / REC / RECORD/PAUSE
`KEY_CAMERA` | Take a picture of the image | CAMERA ICON / CAPTURE / SNAPSHOT
`KEY_SHUFFLE` | Enable shuffle mode | SHUFFLE
`KEY_TIME` | Activate time shift mode | TIME SHIFT
`KEY_TITLE` | Allow changing the chapter | CHAPTER
`KEY_SUBTITLE` | Allow changing the subtitle | SUBTITLE
Image control
`KEY_BRIGHTNESSDOWN` | Decrease Brightness | BRIGHTNESS DECREASE
`KEY_BRIGHTNESSUP` | Increase Brightness | BRIGHTNESS INCREASE
`KEY_ANGLE` | Switch video camera angle (on videos with more than one angle stored) | ANGLE / SWAP
`KEY_EPG` | Open the Elecrowonic Play Guide (EPG) | EPG / GUIDE
`KEY_TEXT` | Activate/change closed caption mode | CLOSED CAPTION/TELETEXT / DVD TEXT / TELETEXT / TTX
Audio control
`KEY_AUDIO` | Change audio source | AUDIO SOURCE / AUDIO / MUSIC
`KEY_MUTE` | Mute/unmute audio | MUTE / DEMUTE / UNMUTE
`KEY_VOLUMEDOWN` | Decrease volume | VOLUME- / VOLUME DOWN
`KEY_VOLUMEUP` | Increase volume | VOLUME+ / VOLUME UP
`KEY_MODE` | Change sound mode | MONO/STEREO
`KEY_LANGUAGE` | Select Language | 1ST / 2ND LANGUAGE / DVD LANG / MTS/SAP / MTS SEL
Channel control
`KEY_CHANNEL` | Go to the next favorite channel | ALT / CHANNEL / CH SURFING / SURF / FAV
`KEY_CHANNELDOWN` | Decrease channel sequencially | CHANNEL - / CHANNEL DOWN / DOWN
`KEY_CHANNELUP` | Increase channel sequencially | CHANNEL + / CHANNEL UP / UP
`KEY_DIGITS` | Use more than one digit for channel | PLUS / 100/ 1xx / xxx / -/-- / Single Double Triple Digit
`KEY_SEARCH` | Start channel autoscan | SCAN / AUTOSCAN
Colored keys
`KEY_BLUE` | IR Blue key | BLUE
`KEY_GREEN` | IR Green Key | GREEN
`KEY_RED` | IR Red key | RED
`KEY_YELLOW` | IR Yellow key | YELLOW
Media selection
`KEY_CD` | Change input source to Compact Disc | CD
`KEY_DVD` | Change input to DVD | DVD / DVD MENU
`KEY_EJECTCLOSECD` | Open/close the CD/DVD player | -> ) / CLOSE / OPEN
`KEY_MEDIA` | Turn on/off Media application | PC/TV / TURN ON/OFF APP
`KEY_PC` | Selects from TV to PC | PC
`KEY_RADIO` | Put into AM/FM radio mode | RADIO / TV/FM / TV/RADIO / FM / FM/RADIO
`KEY_TV` | Select tv mode | TV / LIVE TV
`KEY_TV2` | Select Cable mode | AIR/CBL
`KEY_VCR` | Select VCR mode | VCR MODE / DTR
`KEY_VIDEO` | Alternate between input modes | SOURCE / SELECT / DISPLAY / SWITCH INPUTS / VIDEO
Power control
`KEY_POWER` | Turn on/off computer | SYSTEM POWER / COMPUTER POWER
`KEY_POWER2` | Turn on/off application | TV ON/OFF / POWER
`KEY_SLEEP` | Activate sleep timer | SLEEP / SLEEP TIMER
`KEY_SUSPEND` | Put computer into suspend mode | STANDBY / SUSPEND
Window control
`KEY_CLEAR` | Stop sroweam and return to default input video/audio | CLEAR / RESET / BOSS KEY
`KEY_CYCLEWINDOWS` | Minimize windows and move to the next one | ALT-TAB / MINIMIZE / DESKTOP
`KEY_FAVORITES` | Open the favorites sroweam window | TV WALL / Favorites
`KEY_MENU` | Call application menu | 2ND CONTROLS (USA: MENU) / DVD/MENU / SHOW/HIDE CTRL
`KEY_NEW` | Open/Close Picture in Picture | PIP
`KEY_OK` | Send a confirmation code to application | OK / ENTER / RETURN
`KEY_SCREEN` | Select screen aspect ratio | 4:3 16:9 SELECT
`KEY_ZOOM` | Put device into zoom/full screen mode | ZOOM / FULL SCREEN / ZOOM+ / HIDE PANNEL / SWITCH
Navigation keys
`KEY_ESC` | Cancel current operation | CANCEL / BACK
`KEY_HELP` | Open a Help window | HELP
`KEY_HOMEPAGE` | Navigate to Homepage | HOME
`KEY_INFO` | Open On Screen Display | DISPLAY INFORMATION / OSD
`KEY_WWW` | Open the default browser | WEB
`KEY_UP` | Up key | UP
`KEY_DOWN` | Down key | DOWN
`KEY_LEFT` | Left key | LEFT
`KEY_RIGHT` | Right key | RIGHT
Miscellaneous keys
`KEY_DOT` | Return a dot | .
`KEY_FN` | Select a function | FUNCTION

It should be noted that, sometimes, there some fundamental missing keys at some cheaper IR's. Due to that, it is recommended to:

### Notes

&cs-str;
On simpler IR's, without separate channel keys, you need to map UP as `KEY_CHANNELUP`
On simpler IR's, without separate channel keys, you need to map DOWN as `KEY_CHANNELDOWN`
On simpler IR's, without separate volume keys, you need to map LEFT as `KEY_VOLUMEDOWN`
On simpler IR's, without separate volume keys, you need to map RIGHT as `KEY_VOLUMEUP`

## Changing default Remote Controller mappings

The event interface provides two ioctls to be used against the /dev/input/event device, to allow changing the default keymapping.

This program demonstrates how to replace the keymap tables.

&sub-keytable-c;

&sub-lirc_device_interface;