[Keyboard] Helix add split common option (#7718)

* is_master, has_usb() move to rev2.[hc]

* Do recent helix/rev2 changes to helix/pico as well.

helix/pico/matrix.c: remove 'is_master'
helix/pico/pico.c: add 'is_master'
helix/pico/pico.h: add 'has_usb()' macro
helix/pico/split_util.c: remove 'setup_handedness()' 'has_usb()', add 'is_helix_master()' etc

* add HELIX=scan option into {rev2/pico}/local_features.mk

Made DEBUG_MATRIX_SCAN_RATE easy to use.

* Changed rules.mk to link "helix/local_drivers/ssd1306.c" only when OLED_ENABLE = yes.

* Added option to use split_common for helix/rev2, helix/pico keyboard.

how to build:
 ### build helix/pico (HelixPico) with helix current codes
  $ make helix/pico:KEY_MAP
  $ make helix/pico/back:KEY_MAP

 ### build helix/rev2 (Helix or Helix beta) with helix current codes
  $ make helix:KEY_MAP
  $ make helix/rev2/back:KEY_MAP
  $ make helix/rev2/under:KEY_MAP
  $ make helix/rev2/oled:KEY_MAP
  $ make helix/rev2/oled/back:KEY_MAP
  $ make helix/rev2/oled/under:KEY_MAP

 ### build helix/pico (HelixPico) with split_common codes
  $ make helix/pico/sc:KEY_MAP
  $ make helix/pico/sc/back:KEY_MAP
  $ make helix/pico/sc/under:KEY_MAP

 ### build helix/rev2 (Helix) with split_common codes
  $ make helix/rev2/sc:KEY_MAP
  $ make helix/rev2/sc/back:KEY_MAP
  $ make helix/rev2/sc/under:KEY_MAP
  $ make helix/rev2/sc/oled:KEY_MAP
  $ make helix/rev2/sc/oledback:KEY_MAP
  $ make helix/rev2/sc/oledunder:KEY_MAP

* add matrix_slave_scan_user() to helix/rev2/rev2.c, helix/pico/pico.h

* Changed 'helix:xulkal' to always use split_common and removed ad hoc code.

Added the following line to 'helix/rev2/keymaps/xulkal/rules.mk':

        SPLIT_KEYBOARD = yes

Removed the following ad hoc code from 'users/xulkal/custom_oled.c':

        #if KEYBOARD_helix_rev2
        extern uint8_t is_master;
        bool is_keyboard_master(void) { return is_master; }
        #endif

* add '#define DIODE_DIRECTION COL2ROW' into helix/{rev2|pico}/config.h

This commit does not change the build result.

* update helix readme

* keyboards/helix/readme.md
* keyboards/helix/pico/keymaps/default/readme.md
* keyboards/helix/rev2/keymaps/default/readme.md

Co-authored-by: mtei <2170248+mtei@users.noreply.github.com>

keyboards/helix/pico/local_features.mk

@@ -10,7 +10,7 @@ define HELIX_CUSTOMISE_MSG
   $(info -  OLED_ENABLE          = $(OLED_ENABLE))
   $(info -  LED_BACK_ENABLE      = $(LED_BACK_ENABLE))
   $(info -  LED_UNDERGLOW_ENABLE = $(LED_UNDERGLOW_ENABLE))
-  $(info -  LED_ANIMATION        = $(LED_ANIMATIONS))
+  $(info -  LED_ANIMATIONS       = $(LED_ANIMATIONS))
   $(info -  IOS_DEVICE_ENABLE    = $(IOS_DEVICE_ENABLE))
   $(info )
 endef
@@ -43,12 +43,34 @@ endef
     ifeq ($(findstring ios,$(HELIX)), ios)
       IOS_DEVICE_ENABLE = yes
     endif
+    ifeq ($(findstring scan,$(HELIX)), scan)
+      # use DEBUG_MATRIX_SCAN_RATE
+      # see docs/newbs_testing_debugging.md
+      OPT_DEFS +=  -DDEBUG_MATRIX_SCAN_RATE
+      CONSOLE_ENABLE = yes
+      SHOW_VERBOSE_INFO = yes
+    endif
     ifeq ($(findstring verbose,$(HELIX)), verbose)
-       SHOW_VERBOSE_INFO = yes
+      SHOW_VERBOSE_INFO = yes
     endif
     SHOW_HELIX_OPTIONS = yes
   endif
 
+ifneq ($(strip $(SPLIT_KEYBOARD)), yes)
+  SRC += local_drivers/serial.c
+  KEYBOARD_PATHS += $(HELIX_TOP_DIR)/local_drivers
+
+  # A workaround until #7089 is merged.
+  #   serial.c must not be compiled with the -lto option.
+  #   The current LIB_SRC has a side effect with the -fno-lto option, so use it.
+  LIB_SRC += local_drivers/serial.c
+
+  CUSTOM_MATRIX = yes
+
+  SRC += pico/matrix.c
+  SRC += pico/split_util.c
+endif
+
 ########
 # convert Helix-specific options (that represent combinations of standard options)
 #   into QMK standard options.
@@ -73,11 +95,13 @@ ifeq ($(strip $(LED_ANIMATIONS)), yes)
 endif
 
 ifeq ($(strip $(OLED_ENABLE)), yes)
+    SRC += local_drivers/i2c.c
+    SRC += local_drivers/ssd1306.c
+    KEYBOARD_PATHS += $(HELIX_TOP_DIR)/local_drivers
     OPT_DEFS += -DOLED_ENABLE
-endif
-
-ifeq ($(strip $(LOCAL_GLCDFONT)), yes)
-    OPT_DEFS += -DLOCAL_GLCDFONT
+    ifeq ($(strip $(LOCAL_GLCDFONT)), yes)
+        OPT_DEFS += -DLOCAL_GLCDFONT
+    endif
 endif
 
 ifeq ($(strip $(AUDIO_ENABLE)),yes)
@@ -92,8 +116,10 @@ endif
 ifneq ($(strip $(SHOW_HELIX_OPTIONS)),)
   $(eval $(call HELIX_CUSTOMISE_MSG))
   ifneq ($(strip $(SHOW_VERBOSE_INFO)),)
-     $(info -- RGBLIGHT_ENABLE = $(RGBLIGHT_ENABLE))
-     $(info -- OPT_DEFS        = $(OPT_DEFS))
+     $(info -- RGBLIGHT_ENABLE    = $(RGBLIGHT_ENABLE))
+     $(info -- OLED_DRIVER_ENABLE = $(OLED_DRIVER_ENABLE))
+     $(info -- CONSOLE_ENABLE     = $(CONSOLE_ENABLE))
+     $(info -- OPT_DEFS           = $(OPT_DEFS))
      $(info -- LINK_TIME_OPTIMIZATION_ENABLE = $(LINK_TIME_OPTIMIZATION_ENABLE))
      $(info )
   endif