mb/google/asurada: Implement enable_regulator and regulator_is_enabled

SD Card driver needs to access two regulators - MT6360_LDO5 and
MT6360_LDO3. These two regulators are disabled by default.

Two APIs are implemented:
- mainboard_enable_regulator: Configure the regulator as enabled/disabled.
- mainboard_regulator_is_enabled: Query if the regulator is enabled.

BUG=b:168863056,b:147789962
BRANCH=none
TEST=emerge-asurada coreboot

Change-Id: I391f908fcb33ffdcccc53063644482eabc863ac4
Signed-off-by: Yidi Lin <yidi.lin@mediatek.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46687
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/asurada/Makefile.inc

@@ -20,3 +20,4 @@ ramstage-y += boardid.c
 ramstage-y += chromeos.c
 ramstage-y += mainboard.c
 ramstage-y += reset.c
+ramstage-y += regulator.c

src/mainboard/google/asurada/regulator.c

@@ -15,6 +15,10 @@ static int get_mt6360_regulator_id(enum mtk_regulator regulator)
 		return MT6360_LDO7;
 	case MTK_REGULATOR_VMDDR:
 		return MT6360_LDO6;
+	case MTK_REGULATOR_VCC:
+		return MT6360_LDO5;
+	case MTK_REGULATOR_VCCQ:
+		return MT6360_LDO3;
 	default:
 		break;
 	}
@@ -90,3 +94,42 @@ uint32_t mainboard_get_regulator_vol(enum mtk_regulator regulator)
 
 	return 0;
 }
+
+int mainboard_enable_regulator(enum mtk_regulator regulator, uint8_t enable)
+{
+	/* Return 0 if the regulator is already enabled or disabled. */
+	if (mainboard_regulator_is_enabled(regulator) == enable)
+		return 0;
+
+	int id;
+
+	id = get_mt6360_regulator_id(regulator);
+	if (id < 0) {
+		printk(BIOS_WARNING, "Invalid regulator ID: %d\n", regulator);
+		return -1;
+	}
+
+	return google_chromeec_regulator_enable(id, enable);
+}
+
+uint8_t mainboard_regulator_is_enabled(enum mtk_regulator regulator)
+{
+	int id;
+
+	id = get_mt6360_regulator_id(regulator);
+	if (id < 0) {
+		printk(BIOS_WARNING, "Invalid regulator ID: %d\n; assuming disabled",
+		       regulator);
+		return 0;
+	}
+
+	uint8_t enabled;
+	if (google_chromeec_regulator_is_enabled(id, &enabled) < 0) {
+		printk(BIOS_WARNING,
+		       "Failed to query regulator ID: %d\n; assuming disabled",
+		       regulator);
+		return 0;
+	}
+
+	return enabled;
+}

src/soc/mediatek/common/include/soc/regulator.h

@@ -11,10 +11,15 @@ enum mtk_regulator {
 	MTK_REGULATOR_VDDQ,
 	MTK_REGULATOR_VMDDR,
 	MTK_REGULATOR_VCORE,
+	MTK_REGULATOR_VCC,
+	MTK_REGULATOR_VCCQ,
 };
 
 void mainboard_set_regulator_vol(enum mtk_regulator regulator,
 				 uint32_t voltage_uv);
 uint32_t mainboard_get_regulator_vol(enum mtk_regulator regulator);
 
+int mainboard_enable_regulator(enum mtk_regulator regulator, uint8_t enable);
+uint8_t mainboard_regulator_is_enabled(enum mtk_regulator regulator);
+
 #endif /* SOC_MEDIATEK_COMMON_REGULATOR_H */