HID: apple: option to swap the 'Option' ("Alt") and 'Command' ("Flag") keys.

Use case: people who use both Apple and PC keyboards regularly, and desire to
keep&use their PC muscle memory.

A particular use case: an Apple compact external keyboard connected to a PC
laptop. (This use case can't be covered well by X.org key remappings etc.)

Signed-off-by: Nanno Langstraat <langstr@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/hid/hid-apple.c b/drivers/hid/hid-apple.c
index 881cf7b4f9a4..3b219b9553fb 100644
--- a/drivers/hid/hid-apple.c
+++ b/drivers/hid/hid-apple.c
@@ -46,6 +46,12 @@ module_param(iso_layout, uint, 0644);
 MODULE_PARM_DESC(iso_layout, "Enable/Disable hardcoded ISO-layout of the keyboard. "
                 "(0 = disabled, [1] = enabled)");
 
+static unsigned int swap_opt_cmd = 0;
+module_param(swap_opt_cmd, uint, 0644);
+MODULE_PARM_DESC(swap_opt_cmd, "Swap the Option (\"Alt\") and Command (\"Flag\") keys. "
+                "(For people who want to keep Windows PC keyboard muscle memory. "
+                "[0] = as-is, Mac layout. 1 = swapped, Windows layout.)");
+
 struct apple_sc {
         unsigned long quirks;
         unsigned int fn_on;
@@ -150,6 +156,14 @@ static const struct apple_key_translation apple_iso_keyboard[] = {
         { }
 };
 
+static const struct apple_key_translation swapped_option_cmd_keys[] = {
+        { KEY_LEFTALT,  KEY_LEFTMETA },
+        { KEY_LEFTMETA, KEY_LEFTALT },
+        { KEY_RIGHTALT, KEY_RIGHTMETA },
+        { KEY_RIGHTMETA,KEY_RIGHTALT },
+        { }
+};
+
 static const struct apple_key_translation *apple_find_translation(
                 const struct apple_key_translation *table, u16 from)
 {
@@ -242,6 +256,14 @@ static int hidinput_apple_event(struct hid_device *hid, struct input_dev *input,
                 }
         }
 
+        if (swap_opt_cmd) {
+                trans = apple_find_translation(swapped_option_cmd_keys, usage->code);
+                if (trans) {
+                        input_event(input, usage->type, trans->to, value);
+                        return 1;
+                }
+        }
+
         return 0;
 }