Ergodox Infinity: Add EE_HANDS support. (#9527)

Including a guide to set these EEPROM values (in the readme).

keyboards/ergodox_infinity/matrix.c

@@ -24,6 +24,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "print.h"
 #include "debug.h"
 #include "matrix.h"
+#include "eeconfig.h"
 #include "serial_link/system/serial_link.h"
 
 
@@ -118,8 +119,12 @@ uint8_t matrix_scan(void)
     }
 
     uint8_t offset = 0;
-#ifdef MASTER_IS_ON_RIGHT
+#if (defined(EE_HANDS) || defined(MASTER_IS_ON_RIGHT))
+#ifdef EE_HANDS
+    if (is_serial_link_master() && !eeconfig_read_handedness()) {
+#else
     if (is_serial_link_master()) {
+#endif
         offset = MATRIX_ROWS - LOCAL_MATRIX_ROWS;
     }
 #endif
@@ -162,7 +167,13 @@ void matrix_print(void)
 
 void matrix_set_remote(matrix_row_t* rows, uint8_t index) {
     uint8_t offset = 0;
-#ifdef MASTER_IS_ON_RIGHT
+#ifdef EE_HANDS
+    if (eeconfig_read_handedness()) {
+        offset = LOCAL_MATRIX_ROWS * (index + 1);
+    } else {
+        offset = MATRIX_ROWS - LOCAL_MATRIX_ROWS * (index + 2);
+    }
+#elif defined(MASTER_IS_ON_RIGHT)
     offset = MATRIX_ROWS - LOCAL_MATRIX_ROWS * (index + 2);
 #else
     offset = LOCAL_MATRIX_ROWS * (index + 1);

keyboards/ergodox_infinity/readme.md

@@ -29,6 +29,9 @@ Input Club Infinity Ergodox](https://github.com/fredizzimo/infinity_ergodox/blob
 The Infinity is two completely independent keyboards, that can connect together.
 You have a few options in how you flash the firmware:
 
+- Add `#define EE_HANDS` to your config.h, initialize the EEPROM values (see below),
+  and then flash the same firmware to both halves.
+
 - Flash the left half, rebuild the firmware with "MASTER=right" and then flash
   the right half.  This allows you to plug in either half directly to the
   computer and is what the above instructions do.
@@ -43,6 +46,35 @@ You have a few options in how you flash the firmware:
   directly connect the right half to the computer.
 
 - For minor changes such as changing only the keymap without having updated
-  any part of the firmware code itself, you can program only the MASTER half.
+  any part of the firmware code itself, you can program only the MASTER half,
+  but it is safest to program both halves.
+
+### EE_HANDS initialization
+
+To initialize the EEPROM values for `EE_HANDS` to work properly, these steps should work.
+They only need to be done once, unless you reset the EEPROM later.
+
+  - Plug in the left keyboard half to the computer, and press its program button.
+
+  - Flash the left half with `make ergodox_infinity:default:dfu-util-split-left`
+    (If you need to use a different method to flash your keyboard, still run this command,
+    and abort it with Ctrl+C when the flashing attempts starts to print errors,
+    then flash the built firmware).
+
+  - On the left half, press the top vertical 1.5U key (second from the top in the rightmost column) once,
+    then the 1U key at the bottom in the opposite corner (bottom left corner).
+
+  - Plug in the right keyboard half to the computer, and press its program button.
+
+  - Flash the right half with `make ergodox_infinity:default:dfu-util-split-right`
+
+  - On the right half, press the top vertical 1.5U key (second from the top in the leftmost column) once,
+    then the 1U key at the bottom in the opposite corner (bottom right corner).
+
+  - Add `#define EE_HANDS` to the config.h file of your keymap, and build your firmware using
+    `make ergodox_infinity:keymapname`.
+
+  - After this, you can flash both halves with the same firmware, _without_ having to rebuild with
+    "MASTER=right" or risking a mirrored keyboard when connected the wrong way.
+    If you reset your EEPROM later, you'll have to follow these steps again, though.
 
-- It is safest to program both halves though.