Add bootmagic salt key to avoid accidental configuration

README.md

@@ -124,6 +124,8 @@ Following commands can be also executed with `Magic` + key. In console mode `Mag
 Boot Magic are executed during boot up time. Press Magic key below then pulgin keyboard cable.
 Note that you must use keys of **Layer 0** as Magic keys. These settings are stored in EEPROM so that retain your configure over power cycles.
 
+To avoid configuring accidentally additive salt key `KC_SPACE` also needs to be pressed along with the following configuration keys. The salt key is configurable in `config.h`. See [common/bootmagic.h](common/bootmagic.h).
+
 #### General
 - Skip reading EEPROM to start with default configuration(`ESC`)
 - Clear configuration stored in EEPROM to reset configuration(`Backspace`)

common/bootmagic.c

@@ -5,6 +5,7 @@
 #include "bootloader.h"
 #include "debug.h"
 #include "keymap.h"
+#include "action_layer.h"
 #include "eeconfig.h"
 #include "bootmagic.h"
 
@@ -94,7 +95,7 @@ void bootmagic(void)
     }
 }
 
-bool bootmagic_scan_keycode(uint8_t keycode)
+static bool scan_keycode(uint8_t keycode)
 {
     for (uint8_t r = 0; r < MATRIX_ROWS; r++) {
         matrix_row_t matrix_row = matrix_get_row(r);
@@ -108,3 +109,10 @@ bool bootmagic_scan_keycode(uint8_t keycode)
     }
     return false;
 }
+
+bool bootmagic_scan_keycode(uint8_t keycode)
+{
+    if (!scan_keycode(BOOTMAGIC_KEY_SALT)) return false;
+
+    return scan_keycode(keycode);
+}

common/bootmagic.h

@@ -2,6 +2,12 @@
 #define BOOTMAGIC_H
 
 
+/* bootmagic salt key */
+#ifndef BOOTMAGIC_KEY_SALT
+#define BOOTMAGIC_KEY_SALT              KC_SPACE
+#endif
+
+/* skip bootmagic and eeconfig */
 #ifndef BOOTMAGIC_KEY_SKIP
 #define BOOTMAGIC_KEY_SKIP              KC_ESC
 #endif