mediatek/mt8183: Enable RTC eosc calibration feature to save power

When system shuts down, RTC enable eosc calibration feature to save
power. Then coreboot RTC driver needs to call rtc_enable_dcxo function
at every boot to switch RTC clock source to dcxo.

BUG=b:128467245
BRANCH=none
TEST=Boots correctly on Kukui

Change-Id: Iee21e7611df8959cbbc63b6e6655cfb462147748
Signed-off-by: Ran Bi <ran.bi@mediatek.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32339
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

2 files changed, 27 insertions, 23 deletions

diff --git a/src/soc/mediatek/mt8183/include/soc/rtc.h b/src/soc/mediatek/mt8183/include/soc/rtc.h
index 3d115fec41..841a202519 100644
--- a/src/soc/mediatek/mt8183/include/soc/rtc.h
+++ b/src/soc/mediatek/mt8183/include/soc/rtc.h
@@ -100,18 +100,25 @@ enum {
 };
 
 enum {
-	RTC_EMBCK_SRC_SEL	= 1 << 8,
-	RTC_EMBCK_SEL_MODE	= 3 << 6,
-	RTC_XOSC32_ENB		= 1 << 5,
-	RTC_REG_XOSC32_ENB	= 1 << 15
+	RTC_XOSCCALI_MASK	= 0x1F << 0,
+	RTC_XOSC32_ENB		= 1U << 5,
+	RTC_EMB_HW_MODE		= 0U << 6,
+	RTC_EMB_K_EOSC32_MODE	= 1U << 6,
+	RTC_EMB_SW_DCXO_MODE	= 2U << 6,
+	RTC_EMB_SW_EOSC32_MODE	= 3U << 6,
+	RTC_EMBCK_SEL_MODE_MASK	= 3U << 6,
+	RTC_EMBCK_SRC_SEL	= 1U << 8,
+	RTC_EMBCK_SEL_OPTION	= 1U << 9,
+	RTC_GPS_CKOUT_EN	= 1U << 10,
+	RTC_REG_XOSC32_ENB	= 1U << 15
 };
 
 enum {
-	RTC_LPD_OPT_XOSC_AND_EOSC_LPD	= 0 << 13,
-	RTC_LPD_OPT_EOSC_LPD		= 1 << 13,
-	RTC_LPD_OPT_XOSC_LPD		= 2 << 13,
-	RTC_LPD_OPT_F32K_CK_ALIVE	= 3 << 13,
-	RTC_LPD_OPT_MASK		= 3 << 13
+	RTC_LPD_OPT_XOSC_AND_EOSC_LPD	= 0U << 13,
+	RTC_LPD_OPT_EOSC_LPD		= 1U << 13,
+	RTC_LPD_OPT_XOSC_LPD		= 2U << 13,
+	RTC_LPD_OPT_F32K_CK_ALIVE	= 3U << 13,
+	RTC_LPD_OPT_MASK		= 3U << 13
 };
 
 /* PMIC TOP Register Definition */
diff --git a/src/soc/mediatek/mt8183/rtc.c b/src/soc/mediatek/mt8183/rtc.c
index 62256ebc1b..5879088434 100644
--- a/src/soc/mediatek/mt8183/rtc.c
+++ b/src/soc/mediatek/mt8183/rtc.c
@@ -33,20 +33,19 @@ static int rtc_enable_dcxo(void)
 
 	mdelay(1);
 	if (!rtc_writeif_unlock()) { /* Unlock for reload */
-		rtc_info("rtc_writeif_unlock() fail\n");
+		rtc_info("rtc_writeif_unlock() failed\n");
 		return 0;
 	}
 
 	rtc_read(RTC_OSC32CON, &osc32con);
-	osc32con &= ~RTC_EMBCK_SRC_SEL;
-	osc32con |= RTC_XOSC32_ENB | RTC_REG_XOSC32_ENB;
+	osc32con &= ~(RTC_EMBCK_SRC_SEL | RTC_EMBCK_SEL_MODE_MASK
+		      | RTC_GPS_CKOUT_EN);
+	osc32con |= RTC_XOSC32_ENB | RTC_REG_XOSC32_ENB
+		    | RTC_EMB_K_EOSC32_MODE | RTC_EMBCK_SEL_OPTION;
 	if (!rtc_xosc_write(osc32con)) {
-		rtc_info("rtc_xosc_write() fail\n");
+		rtc_info("rtc_xosc_write() failed\n");
 		return 0;
 	}
-	rtc_read(RTC_BBPU, &bbpu);
-	rtc_write(RTC_BBPU, bbpu | RTC_BBPU_KEY | RTC_BBPU_RELOAD);
-	rtc_write_trigger();
 
 	rtc_read(RTC_CON, &con);
 	rtc_read(RTC_OSC32CON, &osc32con);
@@ -197,12 +196,6 @@ int rtc_init(u8 recover)
 		goto err;
 	}
 
-	/* using dcxo 32K clock */
-	if (!rtc_enable_dcxo()) {
-		ret = -RTC_STATUS_OSC_SETTING_FAIL;
-		goto err;
-	}
-
 	if (recover)
 		mdelay(20);
 
@@ -264,7 +257,7 @@ void poweroff(void)
 	u16 bbpu;
 
 	if (!rtc_writeif_unlock())
-		rtc_info("rtc_writeif_unlock() fail\n");
+		rtc_info("rtc_writeif_unlock() failed\n");
 	/* pull PWRBB low */
 	bbpu = RTC_BBPU_KEY | RTC_BBPU_RELOAD | RTC_BBPU_PWREN;
 	rtc_write(RTC_BBPU, bbpu);
@@ -311,6 +304,10 @@ void rtc_boot(void)
 	pwrap_write_field(PMIC_RG_DCXO_CW02, 0xF, 0xF, 0);
 	pwrap_write_field(PMIC_RG_SCK_TOP_CON0, 0x1, 0x1, 0);
 
+	/* use dcxo 32K clock */
+	if (!rtc_enable_dcxo())
+		rtc_info("rtc_enable_dcxo() failed\n");
+
 	rtc_boot_common();
 	rtc_bbpu_power_on();
 }