From d669736841dc9813fef6780ba833d5cff6ac7605 Mon Sep 17 00:00:00 2001
From: Shunxi Zhang <ot_shunxi.zhang@mediatek.com>
Date: Mon, 10 Feb 2025 16:47:28 +0800
Subject: [PATCH] soc/mediatek/mt8196: Fix RTC recovery by disabling external
 XTAL

Configure PMIC register 0x50c bit0 which decides whether to use external
xtal. This bit of mt6685 should be set to 1, to disable external xtal.

BRANCH=rauru
BUG=b:395485005
TEST=emerge-rauru coreboot chromeos-bootimage, remove battery and
charger, then insert battery and charge, RTC boots normally.

Signed-off-by: Shunxi Zhang <ot_shunxi.zhang@mediatek.com>
Change-Id: Iea44f13af030f24c02993dd43a35a9d8b4f72179
Reviewed-on: https://review.coreboot.org/c/coreboot/+/86353
Reviewed-by: Shunxi Zhang <ot_shunxi.zhang@mediatek.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Yidi Lin <yidilin@google.com>
---
 src/soc/mediatek/mt8196/mt6685_rtc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/soc/mediatek/mt8196/mt6685_rtc.c b/src/soc/mediatek/mt8196/mt6685_rtc.c
index 4564a3144a..4e63f10664 100644
--- a/src/soc/mediatek/mt8196/mt6685_rtc.c
+++ b/src/soc/mediatek/mt8196/mt6685_rtc.c
@@ -345,6 +345,10 @@ static void rtc_recovery_flow(void)
 {
 	printk(BIOS_INFO, "%s: enter\n", __func__);
 
+	config_interface(SCK_TOP_XTAL_SEL_ADDR, 1, SCK_TOP_XTAL_SEL_MASK,
+			 SCK_TOP_XTAL_SEL_SHIFT);
+	udelay(100);
+
 	if (!retry(RECOVERY_RETRY_COUNT,
 		   rtc_frequency_meter_check() &&
 		   rtc_init_after_recovery())) {