Detect SCP version incompatibility

There has been a breaking change in the communication protocols used
between the AP cores and the SCP on CSS based platforms like Juno.
This means both the AP Trusted Firmware and SCP firmware must be
updated at the same time.

In case the user forgets to update the SCP ROM firmware, this patch
detects when it still uses the previous version of the communication
protocol. It will then output a comprehensive error message that helps
trouble-shoot the issue.

Change-Id: I7baf8f05ec0b7d8df25e0ee53df61fe7be0207c2

1 files changed, 18 insertions, 0 deletions

diff --git a/plat/arm/css/common/css_scp_bootloader.c b/plat/arm/css/common/css_scp_bootloader.c
index c6d63f29..6cf1667c 100644
--- a/plat/arm/css/common/css_scp_bootloader.c
+++ b/plat/arm/css/common/css_scp_bootloader.c
@@ -148,6 +148,24 @@ int scp_bootloader_transfer(void *image, unsigned int image_size)
 	cmd_info_payload->checksum = checksum;
 
 	scp_boot_message_send(sizeof(*cmd_info_payload));
+#if CSS_DETECT_PRE_1_7_0_SCP
+	{
+		const uint32_t deprecated_scp_nack_cmd = 0x404;
+		uint32_t mhu_status;
+
+		VERBOSE("Detecting SCP version incompatibility\n");
+
+		mhu_status = mhu_secure_message_wait();
+		if (mhu_status == deprecated_scp_nack_cmd) {
+			ERROR("Detected an incompatible version of the SCP firmware.\n");
+			ERROR("Only versions from v1.7.0 onwards are supported.\n");
+			ERROR("Please update the SCP firmware.\n");
+			return -1;
+		}
+
+		VERBOSE("SCP version looks OK\n");
+	}
+#endif /* CSS_DETECT_PRE_1_7_0_SCP */
 	response = scp_boot_message_wait(sizeof(response));
 	scp_boot_message_end();