Adding Retro_Refit Keyboard

Retro_Refit is an example of using a Teensy to replace a keyboard
controller on an older keyboard. The original 6x15 keyboard had a
non-standard 11x8 matrix.

keyboard/retro_refit/retro_refit.c

@@ -0,0 +1,80 @@
+#include "retro_refit.h"
+
+__attribute__ ((weak))
+void * matrix_init_user(void) {
+	// leave this function blank - it can be defined in a keymap file
+	return NULL;
+};
+
+__attribute__ ((weak))
+void * matrix_scan_user(void) {
+	// leave this function blank - it can be defined in a keymap file
+	return NULL;
+};
+
+__attribute__ ((weak))
+void * led_set_user(uint8_t usb_led) {
+	// leave this function blank - it can be defined in a keymap file
+	return NULL;
+};
+
+void * matrix_init_kb(void) {
+	// put your keyboard start-up code here
+	// runs once when the firmware starts up
+	
+	// Disable status LED on KB, enable status LED on Teensy (KB_STATUS = !TEENSY_STATUS)
+	DDRD |= (1<<6);
+	PORTD |= (1<<6);
+	
+	if (matrix_init_user) {
+		(*matrix_init_user)();
+	}
+	return NULL;
+};
+
+void * matrix_scan_kb(void) {
+    // put your looping keyboard code here
+    // runs every cycle (a lot)
+
+	if (matrix_scan_user) {
+		(*matrix_scan_user)();
+	}
+	return NULL;
+};
+
+void * led_set_kb(uint8_t usb_led) {
+	// put your keyboard LED indicator (ex: Caps Lock LED) toggling code here
+
+    if (usb_led & (1<<USB_LED_CAPS_LOCK)) {
+        // output low
+        DDRD |= (1<<0);
+        PORTD &= ~(1<<0);
+    } else {
+        // Hi-Z
+        DDRD &= ~(1<<0);
+        PORTD &= ~(1<<0);
+    }
+    if (usb_led & (1<<USB_LED_NUM_LOCK)) {
+        // output low
+        DDRD |= (1<<1);
+        PORTD &= ~(1<<1);
+    } else {
+        // Hi-Z
+        DDRD &= ~(1<<1);
+        PORTD &= ~(1<<1);
+    }
+    if (usb_led & (1<<USB_LED_SCROLL_LOCK)) {
+        // output low
+        DDRC |= (1<<6);
+        PORTC &= ~(1<<6);
+    } else {
+        // Hi-Z
+        DDRC &= ~(1<<6);
+        PORTC &= ~(1<<6);
+    }	
+	
+	if (led_set_user) {
+		(*led_set_user)(usb_led);
+	}
+	return NULL;
+};