soc/intel/cannonlake: Fix return values for get_param_value

Commit 41483c9 (soc/intel/cannonlake: Add required FSP UPD changes for
CML) changed the enum values for PCH_SERIAL_IO_MODE so that 0 is
invalid and valid values start from 1. However, get_param_value was
not updated to correctly subtract 1 before returning any value. This
change adds a macro PCH_SERIAL_IO_INDEX to apply the subtract 1
operation on any value that get_param_value needs to return.

BUG=b:128946016
TEST=Verified that hatch boots successfully.

Change-Id: I4e32fcd1efe4a535251f0ec58662a2dc5f70e8b0
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31974
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Rizwan Qureshi <rizwan.qureshi@intel.com>
Reviewed-by: Maulik V Vaghela <maulik.v.vaghela@intel.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/src/soc/intel/cannonlake/fsp_params.c b/src/soc/intel/cannonlake/fsp_params.c
index e3a2310d5c..77d82d64f8 100644
--- a/src/soc/intel/cannonlake/fsp_params.c
+++ b/src/soc/intel/cannonlake/fsp_params.c
@@ -40,22 +40,28 @@ static const int serial_io_dev[] = {
 	PCH_DEVFN_UART2
 };
 
+/*
+ * Given an enum for PCH_SERIAL_IO_MODE, 1 needs to be subtracted to get the FSP
+ * UPD expected value for Serial IO since valid enum index starts from 1.
+ */
+#define PCH_SERIAL_IO_INDEX(x)		((x) - 1)
+
 static uint8_t get_param_value(const config_t *config, uint32_t dev_offset)
 {
 	struct device *dev;
 
 	dev = dev_find_slot(0, serial_io_dev[dev_offset]);
 	if (!dev || !dev->enabled)
-		return PchSerialIoDisabled;
+		return PCH_SERIAL_IO_INDEX(PchSerialIoDisabled);
 
 	if ((config->SerialIoDevMode[dev_offset] >= PchSerialIoMax) ||
 	    (config->SerialIoDevMode[dev_offset] == PchSerialIoNotInitialized))
-		return PchSerialIoPci;
+		return PCH_SERIAL_IO_INDEX(PchSerialIoPci);
 
 	/*
 	 * Correct Enum index starts from 1, so subtract 1 while returning value
 	 */
-	return config->SerialIoDevMode[dev_offset] - 1;
+	return PCH_SERIAL_IO_INDEX(config->SerialIoDevMode[dev_offset]);
 }
 
 #if IS_ENABLED(CONFIG_SOC_INTEL_COMETLAKE)