soc/mediatek/mt8192: ufs: Disable reference clock

UFS reference clock (refclk) is enabled by default, which will cause
the UFSHCI to hold the SPM signal and lead to suspend failure. Since
UFS kernel driver is not built-in, disable refclk in coreboot stage.

Signed-off-by: Wenbin Mei <wenbin.mei@mediatek.com>
Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Change-Id: If11c1b756ad1a0b85f1005f56a6cb4648c687cf0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46408
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/soc/mediatek/mt8192/ufs.c b/src/soc/mediatek/mt8192/ufs.c
new file mode 100644
index 0000000000..2537fa7883
--- /dev/null
+++ b/src/soc/mediatek/mt8192/ufs.c
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <soc/ufs.h>
+
+void ufs_disable_refclk(void)
+{
+	/* disable ref clock to let UFSHCI release SPM signal */
+	write32((void *)UFS_REFCLK_CTRL, 0);
+}