ec/lenovo/h8/smm: Support USB always on AC only

Add support for UAO AC only mode.
Needs tests on all platforms.

Change-Id: Ib52aab427ff687b00129024cde65b78060d21e32
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/20450
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

src/ec/lenovo/h8/smm.c

@@ -18,18 +18,30 @@
 
 #include "h8.h"
 
+enum usb_always_on {
+	UAO_OFF = 0,
+	UAO_AC_AND_BATTERY,
+	UAO_AC_ONLY
+};
+
 void h8_usb_always_on(void)
 {
-	u8 val;
+	enum usb_always_on val;
 	u8 reg;
 
 	if (get_option(&val, "usb_always_on") != CB_SUCCESS)
-		val = 0;
+		val = UAO_OFF;
 
-	if (val) {
+	if (val == UAO_AC_AND_BATTERY) {
 		reg = ec_read(H8_USB_ALWAYS_ON);
 		reg &= ~H8_USB_ALWAYS_ON_AC_ONLY;
 		reg |= H8_USB_ALWAYS_ON_ENABLE;
 		ec_write(H8_USB_ALWAYS_ON, reg);
+	} else if (val == UAO_AC_ONLY) {
+		reg = ec_read(H8_USB_ALWAYS_ON);
+		reg |= H8_USB_ALWAYS_ON_AC_ONLY;
+		reg |= H8_USB_ALWAYS_ON_ENABLE;
+		ec_write(H8_USB_ALWAYS_ON, reg);
+		ec_set_bit(0x2, 3);
 	}
 }

src/mainboard/lenovo/x201/cmos.layout

@@ -125,6 +125,7 @@ enumerations
 10    6     160M
 11    0     Disable
 11    1     AC and battery
+11    2     AC only
 
 # -----------------------------------------------------------------
 checksums

src/mainboard/lenovo/x220/cmos.layout

@@ -136,6 +136,7 @@ enumerations
 11    6	    224M
 12    0     Disable
 12    1     AC and battery
+12    2     AC only
 
 # -----------------------------------------------------------------
 checksums