google/oak: Add derivative board Elm

This patch adds a new mainboard Google/Elm as a derivative of
Google/Oak, using the same code sharing technique for derivative boards
that was pioneered with Google/Veyron*. For now, there are no
firmware-relevant fundamental differences between the two boards.

In addition, introduce a board-specific Kconfig for the "board ID
adjustment" to represent the fact that the Elm board ID space mirrors
the Oak board ID space with an offset of 6, meaning Elm rev0 is
equivalent to Oak rev6, and future board changes will be made on both
boards to maintain this stride (at least virtually... not all of those
revisions will necessarily get built). This should make it much easier
to keep the code that handles revision differences somewhat clean.
(That's the theory, anyway... whether it will work out remains to be
seen.)

BRANCH=None
BUG=None
TEST=Booted Elm image with hardcoded board ID 0 on Oak rev6.

Change-Id: If540aea862b746cf4986a74482ae1764c104fb73
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 53cd85c94945ab0bf14cb88a98e66723fc4483de
Original-Change-Id: Ib05fc81dc4f4308d99e34fce74c6db8b323785da
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/332276
Original-Commit-Ready: Yidi Lin <yidi.lin@mediatek.com>
Original-Tested-by: Yidi Lin <yidi.lin@mediatek.com>
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/14691
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/src/mainboard/google/oak/mainboard.c b/src/mainboard/google/oak/mainboard.c
index 5001a9a..7906593 100644
--- a/src/mainboard/google/oak/mainboard.c
+++ b/src/mainboard/google/oak/mainboard.c
@@ -47,7 +47,7 @@
 {
 	mtk_i2c_bus_init(EXT_BUCK_I2C_BUS);
 
-	switch (board_id()) {
+	switch (board_id() + CONFIG_BOARD_ID_ADJUSTMENT) {
 	case 3:
 	case 4:
 		/* rev-3 and rev-4 use mt6311 as external buck */
@@ -78,7 +78,7 @@
 	mt6391_configure_ldo(LDO_VCAMA, LDO_1P8);
 
 	/* reset ALC5676 */
-	if (board_id() < 5)
+	if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT < 5)
 		gpio_output(PAD_LCM_RST, 1);
 
 	/* SoC I2S */
@@ -87,7 +87,7 @@
 	gpio_set_mode(PAD_I2S0_MCK, PAD_I2S0_MCK_FUNC_I2S1_MCK);
 	gpio_set_mode(PAD_I2S0_DATA0, PAD_I2S0_DATA0_FUNC_I2S1_DO_1);
 	gpio_set_mode(PAD_I2S0_DATA1, PAD_I2S0_DATA1_FUNC_I2S2_DI_2);
-	if (board_id() >= 5)
+	if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT >= 5)
 		gpio_set_mode(PAD_UCTS0, PAD_UCTS0_FUNC_I2S2_DI_1);
 
 	/* codec ext MCLK ON */
@@ -105,7 +105,7 @@
 {
 	setup_usb_host();
 
-	if (board_id() > 3) {
+	if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT > 3) {
 		/* Enable current limit */
 		gpio_output(PAD_CM2MCLK, 1);
 		/* Configure USB OC pins*/
@@ -114,7 +114,7 @@
 		gpio_input_pullup(PAD_PCM_SYNC);
 	}
 
-	if (board_id() > 4) {
+	if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT > 4) {
 		/* USB 2.0 type A port over current interrupt pin(low active) */
 		gpio_input_pullup(PAD_UCTS2);
 		/* USB 2.0 type A port BC1.2 STATUS(low active) */
@@ -125,7 +125,7 @@
 static void configure_usb_hub(void)
 {
 	/* set usb hub reset pin (low active) to high */
-	if (board_id() > 4)
+	if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT > 4)
 		gpio_output(PAD_UTXD3, 1);
 }
 
@@ -133,7 +133,7 @@
 static void configure_backlight(void)
 {
 	/* Configure PANEL_LCD_POWER_EN */
-	switch (board_id()) {
+	switch (board_id() + CONFIG_BOARD_ID_ADJUSTMENT) {
 	case 1:
 	case 2:
 		break;
@@ -156,7 +156,7 @@
 {
 	mtcmos_display_power_on();
 
-	switch (board_id()) {
+	switch (board_id() + CONFIG_BOARD_ID_ADJUSTMENT) {
 	case 0:
 		/* board from Rev0, Rev1 */
 		/* vgp2 set to 1.8V for it6151 */
@@ -182,11 +182,17 @@
 		mt6391_configure_ldo(LDO_VGP2, LDO_3P3);
 		gpio_output(PAD_URTS0, 0); /* PS8640_SYSRSTN */
 		/* PS8640_1V2_ENABLE */
-		gpio_output(board_id() == 4 ? PAD_SRCLKENAI2 : PAD_URTS2, 1);
+		if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT == 4)
+			gpio_output(PAD_SRCLKENAI2, 1);
+		else
+			gpio_output(PAD_URTS2, 1);
 		/* delay 2ms for vgp2 and PS8640_1V2_ENABLE stable */
 		mdelay(2);
 		/* PS8640_PDN */
-		gpio_output(board_id() > 4 ? PAD_LCM_RST : PAD_UCTS0, 1);
+		if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT > 4)
+			gpio_output(PAD_LCM_RST, 1);
+		else
+			gpio_output(PAD_UCTS0, 1);
 		gpio_output(PAD_PCM_CLK, 1); /* PS8640_MODE_CONF */
 		gpio_output(PAD_URTS0, 1); /* PS8640_SYSRSTN */
 		/* for level shift(1.8V to 3.3V) on */
@@ -200,7 +206,7 @@
 	u8 i2c_bus;
 	int ret;
 
-	switch (board_id()) {
+	switch (board_id() + CONFIG_BOARD_ID_ADJUSTMENT) {
 	case 0:
 	case 1:
 		i2c_bus = 3;
@@ -240,7 +246,7 @@
 	/* TP_SHIFT_EN: Enables the level shifter for I2C bus 4 (TPAD), which
 	 * also contains the PS8640 eDP brige and the USB hub.
 	 */
-	if (board_id() < 5)
+	if (board_id() + CONFIG_BOARD_ID_ADJUSTMENT < 5)
 		mt6391_gpio_output(MT6391_KP_ROW2, 1);
 
 	/* Config SD card detection pin */