Simplify split_common Code significantly (#4772)

* Eliminate separate slave loop

Both master and slave run the standard keyboard_task main loop now.

* Refactor i2c/serial specific code

Simplify some of the preprocessor mess by using common function names.

* Fix missing #endif

* Move direct pin mapping support from miniaxe to split_common

For boards with more pins than sense--sorry, switches.

* Reordering and reformatting only

* Don't run matrix_scan_quantum on slave side

* Clean up the offset/slaveOffset calculations

* Cut undebounced matrix size in half

* Refactor debouncing

* Minor fixups

* Split split_common transport and debounce code into their own files

Can now be replaced with custom versions per keyboard using
CUSTOM_TRANSPORT = yes and CUSTOM_DEBOUNCE = yes

* Refactor debounce for non-split keyboards too

* Update handwired/xealous to build using new split_common

* Fix debounce breaking basic test

* Dodgy method to allow a split kb to only include one of i2c/serial

SPLIT_TRANSPORT = serial or SPLIT_TRANSPORT = i2c will include only
that driver code in the binary.

SPLIT_TRANSPORT = custom (or anything else) will include neither, the
keyboard must supply it's own code

if SPLIT_TRANSPORT is not defined then the original behaviour (include
both avr i2c and serial code) is maintained.

This could be better but it would require explicitly updating all the
existing split keyboards.

* Enable LTO to get lets_split/sockets under the line

* Add docs for SPLIT_TRANSPORT, CUSTOM_MATRIX, CUSTOM_DEBOUNCE

* Remove avr-specific sei() from split matrix_setup

Not needed now that slave doesn't have a separate main loop.
Both sides (on avr) call sei() in lufa's main() after exiting
keyboard_setup().

* Fix QUANTUM_LIB_SRC references and simplify SPLIT_TRANSPORT.

* Add comments and fix formatting.

1 files changed, 13 insertions, 1 deletions

diff --git a/docs/getting_started_make_guide.md b/docs/getting_started_make_guide.md
index adc1aed75..bb7e1e7e3 100644
--- a/docs/getting_started_make_guide.md
+++ b/docs/getting_started_make_guide.md
@@ -97,7 +97,7 @@ This allows you to send Unicode characters using `UC(<code point>)` in your keym
 
 `UNICODEMAP_ENABLE`
 
-This allows you to send Unicode characters using `X(<map index>)` in your keymap. You will need to maintain a mapping table in your keymap file. All possible code points (up to `0x10FFFF`) are supported. 
+This allows you to send Unicode characters using `X(<map index>)` in your keymap. You will need to maintain a mapping table in your keymap file. All possible code points (up to `0x10FFFF`) are supported.
 
 `UCIS_ENABLE`
 
@@ -135,6 +135,18 @@ This enables [key lock](feature_key_lock.md). This consumes an additional 260 by
 
 This enables split keyboard support (dual MCU like the let's split and bakingpy's boards) and includes all necessary files located at quantum/split_common
 
+`SPLIT_TRANSPORT`
+
+As there is no standard split communication driver for ARM-based split keyboards yet, `SPLIT_TRANSPORT = custom` must be used for these. It will prevent the standard split keyboard communication code (which is AVR-specific) from being included, allowing a custom implementation to be used.
+
+`CUSTOM_MATRIX`
+
+Lets you replace the default matrix scanning routine with your own code. You will need to provide your own implementations of matrix_init() and matrix_scan().
+
+`CUSTOM_DEBOUNCE`
+
+Lets you replace the default key debouncing routine with your own code. You will need to provide your own implementation of debounce().
+
 ## Customizing Makefile Options on a Per-Keymap Basis
 
 If your keymap directory has a file called `rules.mk` any options you set in that file will take precedence over other `rules.mk` options for your particular keyboard.