Change in coreboot[master]: soc/amd/common/block/spi: Disable SPI Clock Pulldown

[Karthik Ramasubramanian (Code Review)]

Karthik Ramasubramanian has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/63307 )

Change subject: soc/amd/common/block/spi: Disable SPI Clock Pulldown
......................................................................

soc/amd/common/block/spi: Disable SPI Clock Pulldown

SPI Clock pulldown is enabled by default. When the bus is idle, this
causes the clock signal to be pulled down to 1.3V. Disable the SPI Clock
pulldown so that it is parked correctly at idle state.

BUG=b:226634752
TEST=Build and boot to OS in Skyrim. Ensure that the SPI clock pulldown
is disabled.

Signed-off-by: Karthikeyan Ramasubramanian 
Change-Id: If62a1f51ac3d68e7896baac3c696c4f73d900f6d
---
M src/soc/amd/common/block/include/amdblocks/acpimmio.h
M src/soc/amd/common/block/spi/fch_spi.c
2 files changed, 8 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/07/63307/1

diff --git a/src/soc/amd/common/block/include/amdblocks/acpimmio.h b/src/soc/amd/common/block/include/amdblocks/acpimmio.h
index 2d632f6..6694e80 100644
--- a/src/soc/amd/common/block/include/amdblocks/acpimmio.h
+++ b/src/soc/amd/common/block/include/amdblocks/acpimmio.h
@@ -32,6 +32,8 @@
 #define   SLPTYPE_CONTROL_EN		(1 << 5)
 #define   KBRSTEN			(1 << 4)
 #define PM_RST_STATUS			0xc0
+#define PM_SPI_PAD_PUPD			0x90
+#define  PM_SPI_CLK_PD_EN		(1 << 11)

/*
  * Earlier devices enable the ACPIMMIO bank decodes in PMx24. All discrete FCHs
diff --git a/src/soc/amd/common/block/spi/fch_spi.c b/src/soc/amd/common/block/spi/fch_spi.c
index 5ef900c..a3a721a 100644
--- a/src/soc/amd/common/block/spi/fch_spi.c
+++ b/src/soc/amd/common/block/spi/fch_spi.c
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */

+#include <amdblocks/acpimmio.h>
 #include <amdblocks/chip.h>
 #include <amdblocks/lpc.h>
 #include <amdblocks/psp_efs.h>
@@ -125,4 +126,9 @@
    lpc_enable_spi_prefetch();
    fch_spi_configure_4dw_burst();
    fch_spi_config_modes();
+	/*
+	 * SPI Clock Pulldown is enabled by default. Disable SPI Clock Pulldown so that
+	 * the clock signal is parked correctly at idle state.
+	 */
+	pm_write32(PM_SPI_PAD_PUPD, pm_read32(PM_SPI_PAD_PUPD) & ~PM_SPI_CLK_PD_EN);
 }