Patched in diff file applefn.patch for Apple fn key

qmk#2179

From Issue qmk#2179 of qmk/qmk_firmware, user fauxpark mentions how to enable the Apple 'fn' key in QMK.

A link to applefn.patch is in the issue link above,
and was patched into qmk_firmware with this command:
(applefn.patch was already copied into ./qmk_firmware)

```c
% cd qmk_firmware
% patch -ruN -d ./ < applefn.patch
```

In order to be able to use the Apple fn key keycode --
KC_APPLE_FN, or alternatively, KC_APFN,
you must define the following directives in the config.h
file for your keyboard's config.h:

```c
#define VENDOR_ID 0x05ac
#define PRODUCT_ID 0x024f
#define APPLE_FN_ENABLE
```

macOS must "think" your keyboard is one of their own -- the PRODUCT_ID corresponds to the Apple Pro Keyboard.

This commit already has the patch applied,
so the KC_APPLE_FN (KC_APFN) keycode may be used
in all layouts from here on out.

Author: galudino

common_features.mk

@@ -521,3 +521,7 @@ ifeq ($(strip $(AUTO_SHIFT_ENABLE)), yes)
         OPT_DEFS += -DAUTO_SHIFT_MODIFIERS
     endif
 endif
+
+ifeq ($(strip $(APPLE_FN_ENABLE)), yes)
+    OPT_DEFS += -DAPPLE_FN_ENABLE
+endif

quantum/keymap_common.c

@@ -68,6 +68,11 @@ action_t action_for_key(uint8_t layer, keypos_t key) {
             action.code = ACTION_USAGE_CONSUMER(KEYCODE2CONSUMER(keycode));
             break;
 #endif
+#ifdef APPLE_FN_ENABLE
+        case KC_APPLE_FN:
+            action.code = ACTION_APPLE_FN();
+            break;
+#endif
 #ifdef MOUSEKEY_ENABLE
         case KC_MS_UP ... KC_MS_ACCEL2:
             action.code = ACTION_MOUSEKEY(keycode);

tmk_core/common/action.c

@@ -389,6 +389,16 @@ void process_action(keyrecord_t *record, action_t action) {
             }
             break;
 #endif
+#ifdef APPLE_FN_ENABLE
+        /* Apple Fn */
+        case ACT_APPLE_FN:
+            if (event.pressed) {
+                register_code(KC_APPLE_FN);
+            } else {
+                unregister_code(KC_APPLE_FN);
+            }
+            break;
+#endif
 #ifdef MOUSEKEY_ENABLE
         /* Mouse key */
         case ACT_MOUSEKEY:
@@ -806,6 +816,12 @@ void register_code(uint8_t code) {
     else if
         IS_CONSUMER(code) { host_consumer_send(KEYCODE2CONSUMER(code)); }
 #endif
+#ifdef APPLE_FN_ENABLE
+    else if IS_APPLE_FN(code) {
+        add_key(code);
+        send_keyboard_report();
+    }
+#endif
 #ifdef MOUSEKEY_ENABLE
     else if
         IS_MOUSEKEY(code) {
@@ -870,6 +886,12 @@ void unregister_code(uint8_t code) {
         IS_SYSTEM(code) { host_system_send(0); }
     else if
         IS_CONSUMER(code) { host_consumer_send(0); }
+#ifdef APPLE_FN_ENABLE
+    else if IS_APPLE_FN(code) {
+        del_key(code);
+        send_keyboard_report();
+    }
+#endif
 #ifdef MOUSEKEY_ENABLE
     else if
         IS_MOUSEKEY(code) {
@@ -1053,6 +1075,9 @@ void debug_action(action_t action) {
         case ACT_USAGE:
             dprint("ACT_USAGE");
             break;
+        case ACT_APPLE_FN:
+            dprint("ACT_APPLE_FN");
+            break;
         case ACT_MOUSEKEY:
             dprint("ACT_MOUSEKEY");
             break;

tmk_core/common/action_code.h

@@ -51,7 +51,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
  * ACT_SWAP_HANDS(0110):
  * 0110|xxxx| keycode     Swap hands (keycode on tap, or options)
  *
- * 0111|xxxx xxxx xxxx    (reserved)
+ * ACT_APPLE_FN(0111):
+ * 0111|0000|0000|0000    Apple Fn
  *
  * Layer Actions(10xx)
  * -------------------
@@ -106,6 +107,8 @@ enum action_kind_id {
     ACT_MOUSEKEY = 0b0101,
     /* One-hand Support */
     ACT_SWAP_HANDS = 0b0110,
+    /* Apple Fn */
+    ACT_APPLE_FN = 0b0111,
     /* Layer Actions */
     ACT_LAYER         = 0b1000,
     ACT_LAYER_MODS    = 0b1001,
@@ -216,6 +219,7 @@ enum mods_codes {
 enum usage_pages { PAGE_SYSTEM, PAGE_CONSUMER };
 #define ACTION_USAGE_SYSTEM(id) ACTION(ACT_USAGE, PAGE_SYSTEM << 10 | (id))
 #define ACTION_USAGE_CONSUMER(id) ACTION(ACT_USAGE, PAGE_CONSUMER << 10 | (id))
+#define ACTION_APPLE_FN() ACTION(ACT_APPLE_FN, 0)
 #define ACTION_MOUSEKEY(key) ACTION(ACT_MOUSEKEY, key)
 
 /** \brief Layer Actions

tmk_core/common/keycode.h

@@ -34,6 +34,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define IS_SPECIAL(code) ((0xA5 <= (code) && (code) <= 0xDF) || (0xE8 <= (code) && (code) <= 0xFF))
 #define IS_SYSTEM(code) (KC_PWR <= (code) && (code) <= KC_WAKE)
 #define IS_CONSUMER(code) (KC_MUTE <= (code) && (code) <= KC_BRID)
+#define IS_APPLE_FN(code) (KC_APFN == (code))
 
 #define IS_FN(code) (KC_FN0 <= (code) && (code) <= KC_FN31)
 
@@ -191,6 +192,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define KC_BRIU KC_BRIGHTNESS_UP
 #define KC_BRID KC_BRIGHTNESS_DOWN
 
+/* Apple Fn */
+#define KC_APFN KC_APPLE_FN
+
 /* System Specific */
 #define KC_BRMU KC_PAUSE
 #define KC_BRMD KC_SCROLLLOCK
@@ -484,6 +488,9 @@ enum internal_special_keycodes {
     KC_BRIGHTNESS_UP,
     KC_BRIGHTNESS_DOWN,
 
+    /* Apple Fn */
+    KC_APPLE_FN,
+
     /* Fn keys */
     KC_FN0 = 0xC0,
     KC_FN1,

tmk_core/common/report.c

@@ -231,6 +231,12 @@ void del_key_bit(report_keyboard_t* keyboard_report, uint8_t code) {
  * FIXME: Needs doc
  */
 void add_key_to_report(report_keyboard_t* keyboard_report, uint8_t key) {
+#ifdef APPLE_FN_ENABLE
+    if IS_APPLE_FN(key) {
+        keyboard_report->reserved = 1;
+        return;
+    }
+#endif
 #ifdef NKRO_ENABLE
     if (keyboard_protocol && keymap_config.nkro) {
         add_key_bit(keyboard_report, key);
@@ -245,6 +251,12 @@ void add_key_to_report(report_keyboard_t* keyboard_report, uint8_t key) {
  * FIXME: Needs doc
  */
 void del_key_from_report(report_keyboard_t* keyboard_report, uint8_t key) {
+#ifdef APPLE_FN_ENABLE
+    if IS_APPLE_FN(key) {
+        keyboard_report->reserved = 0;
+        return;
+    }
+#endif
 #ifdef NKRO_ENABLE
     if (keyboard_protocol && keymap_config.nkro) {
         del_key_bit(keyboard_report, key);

tmk_core/protocol/usb_descriptor.c

@@ -67,10 +67,22 @@ const USB_Descriptor_HIDReport_Datatype_t PROGMEM KeyboardReport[] = {
         HID_RI_REPORT_COUNT(8, 0x08),
         HID_RI_REPORT_SIZE(8, 0x01),
         HID_RI_INPUT(8, HID_IOF_DATA | HID_IOF_VARIABLE | HID_IOF_ABSOLUTE),
+
+#ifdef APPLE_FN_ENABLE
+        HID_RI_USAGE_PAGE(8, 0xFF),    // AppleVendor Top Case
+        HID_RI_USAGE(8, 0x03),         // KeyboardFn
+        HID_RI_LOGICAL_MINIMUM(8, 0x00),
+        HID_RI_LOGICAL_MAXIMUM(8, 0x01),
+        HID_RI_REPORT_COUNT(8, 0x01),
+        HID_RI_REPORT_SIZE(8, 0x08),
+        HID_RI_INPUT(8, HID_IOF_DATA | HID_IOF_VARIABLE | HID_IOF_ABSOLUTE),
+#else
         // Reserved (1 byte)
         HID_RI_REPORT_COUNT(8, 0x01),
         HID_RI_REPORT_SIZE(8, 0x08),
         HID_RI_INPUT(8, HID_IOF_CONSTANT),
+#endif
+
         // Keycodes (6 bytes)
         HID_RI_USAGE_PAGE(8, 0x07),    // Keyboard/Keypad
         HID_RI_USAGE_MINIMUM(8, 0x00),

tmk_core/protocol/vusb/vusb.c

@@ -380,10 +380,22 @@ const PROGMEM uchar keyboard_hid_report[] = {
     0x95, 0x08,  //   Report Count (8)
     0x75, 0x01,  //   Report Size (1)
     0x81, 0x02,  //   Input (Data, Variable, Absolute)
+
+#ifdef APPLE_FN_ENABLE
+    0x05, 0xFF,  //   Usage Page (AppleVendor Top Case)
+    0x09, 0x03,  //   Usage (KeyboardFn)
+    0x15, 0x00,  //   Logical Minimum (0)
+    0x25, 0x01,  //   Logical Maximum (1)
+    0x95, 0x01,  //   Report Count (1)
+    0x75, 0x08,  //   Report Size (8)
+    0x81, 0x02,  //   Input (Data, Variable, Absolute)
+#else
     // Reserved (1 byte)
     0x95, 0x01,  //   Report Count (1)
     0x75, 0x08,  //   Report Size (8)
     0x81, 0x03,  //   Input (Constant)
+#endif
+
     // Keycodes (6 bytes)
     0x05, 0x07,        //   Usage Page (Keyboard/Keypad)
     0x19, 0x00,        //   Usage Minimum (0)