HID: wiimote: Parse nunchuck data

The Nintendo Nunchuck extension reports accelerometer values, one analog stick
and two buttons. See inline comments for data layout.
We report all data to userspace through extension input device.
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-wiimote-ext.c

@@ -36,6 +36,17 @@ enum wiiext_type {
 	WIIEXT_NUNCHUCK,	/* Nintendo nunchuck controller */
 };
 
+enum wiiext_keys {
+	WIIEXT_KEY_C,
+	WIIEXT_KEY_Z,
+	WIIEXT_KEY_COUNT
+};
+
+static __u16 wiiext_keymap[] = {
+	BTN_C,		/* WIIEXT_KEY_C */
+	BTN_Z,		/* WIIEXT_KEY_Z */
+};
+
 /* diable all extensions */
 static void ext_disable(struct wiimote_ext *ext)
 {
@@ -272,6 +283,82 @@ static void handler_motionp(struct wiimote_ext *ext, const __u8 *payload)
 
 static void handler_nunchuck(struct wiimote_ext *ext, const __u8 *payload)
 {
+	__s16 x, y, z, bx, by;
+
+	/*   Byte |   8    7 |  6    5 |  4    3 |  2 |  1  |
+	 *   -----+----------+---------+---------+----+-----+
+	 *    1   |              Button X <7:0>             |
+	 *    2   |              Button Y <7:0>             |
+	 *   -----+----------+---------+---------+----+-----+
+	 *    3   |               Speed X <9:2>             |
+	 *    4   |               Speed Y <9:2>             |
+	 *    5   |               Speed Z <9:2>             |
+	 *   -----+----------+---------+---------+----+-----+
+	 *    6   | Z <1:0>  | Y <1:0> | X <1:0> | BC | BZ  |
+	 *   -----+----------+---------+---------+----+-----+
+	 * Button X/Y is the analog stick. Speed X, Y and Z are the
+	 * accelerometer data in the same format as the wiimote's accelerometer.
+	 * The 6th byte contains the LSBs of the accelerometer data.
+	 * BC and BZ are the C and Z buttons: 0 means pressed
+	 *
+	 * If reported interleaved with motionp, then the layout changes. The
+	 * 5th and 6th byte changes to:
+	 *   -----+-----------------------------------+-----+
+	 *    5   |            Speed Z <9:3>          | EXT |
+	 *   -----+--------+-----+-----+----+----+----+-----+
+	 *    6   |Z <2:1> |Y <1>|X <1>| BC | BZ | 0  |  0  |
+	 *   -----+--------+-----+-----+----+----+----+-----+
+	 * All three accelerometer values lose their LSB. The other data is
+	 * still available but slightly moved.
+	 *
+	 * Center data for button values is 128. Center value for accelerometer
+	 * values it 512 / 0x200
+	 */
+
+	bx = payload[0];
+	by = payload[1];
+	bx -= 128;
+	by -= 128;
+
+	x = payload[2] << 2;
+	y = payload[3] << 2;
+	z = payload[4] << 2;
+
+	if (ext->motionp) {
+		x |= (payload[5] >> 3) & 0x02;
+		y |= (payload[5] >> 4) & 0x02;
+		z &= ~0x4;
+		z |= (payload[5] >> 5) & 0x06;
+	} else {
+		x |= (payload[5] >> 2) & 0x03;
+		y |= (payload[5] >> 4) & 0x03;
+		z |= (payload[5] >> 6) & 0x03;
+	}
+
+	x -= 0x200;
+	y -= 0x200;
+	z -= 0x200;
+
+	input_report_abs(ext->input, ABS_HAT0X, bx);
+	input_report_abs(ext->input, ABS_HAT0Y, by);
+
+	input_report_abs(ext->input, ABS_RX, x);
+	input_report_abs(ext->input, ABS_RY, y);
+	input_report_abs(ext->input, ABS_RZ, z);
+
+	if (ext->motionp) {
+		input_report_key(ext->input,
+			wiiext_keymap[WIIEXT_KEY_Z], !!(payload[5] & 0x04));
+		input_report_key(ext->input,
+			wiiext_keymap[WIIEXT_KEY_C], !!(payload[5] & 0x08));
+	} else {
+		input_report_key(ext->input,
+			wiiext_keymap[WIIEXT_KEY_Z], !!(payload[5] & 0x01));
+		input_report_key(ext->input,
+			wiiext_keymap[WIIEXT_KEY_C], !!(payload[5] & 0x02));
+	}
+
+	input_sync(ext->input);
 }
 
 static void handler_classic(struct wiimote_ext *ext, const __u8 *payload)
@@ -383,7 +470,7 @@ int wiiext_init(struct wiimote_data *wdata)
 {
 	struct wiimote_ext *ext;
 	unsigned long flags;
-	int ret;
+	int ret, i;
 
 	ext = kzalloc(sizeof(*ext), GFP_KERNEL);
 	if (!ext)
@@ -408,6 +495,22 @@ int wiiext_init(struct wiimote_data *wdata)
 	ext->input->id.version = wdata->hdev->version;
 	ext->input->name = WIIMOTE_NAME " Extension";
 
+	set_bit(EV_KEY, ext->input->evbit);
+	for (i = 0; i < WIIEXT_KEY_COUNT; ++i)
+		set_bit(wiiext_keymap[i], ext->input->keybit);
+
+	set_bit(EV_ABS, ext->input->evbit);
+	set_bit(ABS_HAT0X, ext->input->absbit);
+	set_bit(ABS_HAT0Y, ext->input->absbit);
+	input_set_abs_params(ext->input, ABS_HAT0X, -120, 120, 2, 4);
+	input_set_abs_params(ext->input, ABS_HAT0Y, -120, 120, 2, 4);
+	set_bit(ABS_RX, ext->input->absbit);
+	set_bit(ABS_RY, ext->input->absbit);
+	set_bit(ABS_RZ, ext->input->absbit);
+	input_set_abs_params(ext->input, ABS_RX, -500, 500, 2, 4);
+	input_set_abs_params(ext->input, ABS_RY, -500, 500, 2, 4);
+	input_set_abs_params(ext->input, ABS_RZ, -500, 500, 2, 4);
+
 	ret = input_register_device(ext->input);
 	if (ret) {
 		input_free_device(ext->input);