mb/google/bluey: Add disable slow charging support

This commit adds a new function, disable_slow_battery_charging, to
disable charging on the Bluey mainboard. This function writes a disable
command to the SMBUS chargers, turning off the charging process.

Additionally, this patch makes the following changes to support this
new functionality:
 - The charging.c file is now compiled in both the romstage and
   ramstage phases.
 - The new disable_slow_battery_charging function is declared in
   board.h.
 - A new charging_status enum is introduced to clearly define the
   charging states.

These changes ensure that the system can now properly control charging,
allowing it to be disabled when necessary.

BUG=b:439819922
TEST=Able to build and boot google/quenbi.

Change-Id: Ic0c59e0509889e6d166becf76279718b853021cc
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89022
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/bluey/Makefile.mk

@@ -12,4 +12,6 @@ romstage-y += romstage.c
 
 romstage-y += charging.c
 
+ramstage-y += charging.c
+
 ramstage-y += mainboard.c

src/mainboard/google/bluey/board.h

@@ -39,5 +39,6 @@
 
 void setup_chromeos_gpios(void);
 void enable_slow_battery_charging(void);
+void disable_slow_battery_charging(void);
 
 #endif /* MAINBOARD_GOOGLE_BLUEY_BOARD_H */

src/mainboard/google/bluey/charging.c

@@ -13,7 +13,11 @@
 #define SMB2_CHGR_CHRG_EN_CMD ((SMB2_SLAVE_ID << 16) | SCHG_CHGR_CHARGING_ENABLE_CMD)
 
 #define FCC_1A_STEP_50MA 0x14
-#define CHRG_ENABLE 0x01
+
+enum charging_status {
+	CHRG_DISABLE,
+	CHRG_ENABLE,
+};
 
 /*
  * Enable charging w/ 1A Icurrent supply at max.
@@ -27,3 +31,13 @@ void enable_slow_battery_charging(void)
 	spmi_write8(SMB1_CHGR_CHRG_EN_CMD, CHRG_ENABLE);
 	spmi_write8(SMB2_CHGR_CHRG_EN_CMD, CHRG_ENABLE);
 }
+
+/*
+ * Disable charging.
+ */
+void disable_slow_battery_charging(void)
+{
+	printk(BIOS_INFO, "Disable slow charge support\n");
+	spmi_write8(SMB1_CHGR_CHRG_EN_CMD, CHRG_DISABLE);
+	spmi_write8(SMB2_CHGR_CHRG_EN_CMD, CHRG_DISABLE);
+}