cr50: add RO image hash base to the reported FW version

The CR50 RO version is identified not just by the git hash, but also
by the fuse settings and keys used for signing. The first four bytes
of the entire RO image's hash are saved in the image header. Adding
these four bytes to the version string reported to the host allows to
uniquely identify both RO and RW firmware versions.

BRANCH=none
BUG=none
TEST=verified that the appropriate string is showing up:
  localhost ~ # grep cr50 /sys/firmware/log
  Firmware version: RO: 97594095 RW: cr50_v1.1.4803-dcac93a-dirty
  localhost ~ #

Change-Id: I30a21fad15d99523b1edfa1baa32d80b44e7d0df
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/356735
Reviewed-by: Scott Collyer <scollyer@chromium.org>

1 files changed, 21 insertions, 6 deletions

diff --git a/common/tpm_registers.c b/common/tpm_registers.c
index 455f94d44f..24c56ca475 100644
--- a/common/tpm_registers.c
+++ b/common/tpm_registers.c
@@ -12,6 +12,8 @@
 #include "byteorder.h"
 #include "console.h"
 #include "extension.h"
+#include "printf.h"
+#include "signed_header.h"
 #include "system.h"
 #include "task.h"
 #include "tpm_registers.h"
@@ -106,8 +108,8 @@ enum tpm_sts_bits {
 #define TPM_FW_VER_MAX_SIZE 64
 /* Used to count bytes read in version string */
 static int tpm_fw_ver_index;
-/* Pointer to version string */
-static const uint8_t *tpm_fw_ver_ptr;
+ /* 50 bytes should be enough for the version strings. */
+static uint8_t tpm_fw_ver[50];
 
 static void set_tpm_state(enum tpm_states state)
 {
@@ -422,14 +424,14 @@ void tpm_register_get(uint32_t regaddr, uint8_t *dest, uint32_t data_size)
 			 * maximum allowed version string size.
 			 */
 			if (tpm_fw_ver_index < TPM_FW_VER_MAX_SIZE) {
-				*dest++ = tpm_fw_ver_ptr[tpm_fw_ver_index];
+				*dest++ = tpm_fw_ver[tpm_fw_ver_index];
 				/*
 				 * If reached end of string, then don't update
 				 * the index so that it will keep pointing at
 				 * the end of string character and continue to
 				 * fill *dest with 0s.
 				 */
-				if (tpm_fw_ver_ptr[tpm_fw_ver_index] != '\0')
+				if (tpm_fw_ver[tpm_fw_ver_index] != '\0')
 					tpm_fw_ver_index++;
 			} else
 				/* Not in a valid state, just stuff 0s */
@@ -450,8 +452,6 @@ static void tpm_init(void)
 	tpm_.regs.access = tpm_reg_valid_sts;
 	tpm_.regs.sts = (tpm_family_tpm2 << tpm_family_shift) |
 		(64 << burst_count_shift) | sts_valid;
-	/* Set FW version pointer to start of version string */
-	tpm_fw_ver_ptr = system_get_version(SYSTEM_IMAGE_RW);
 
 	/* TPM2 library functions. */
 	_plat__Signal_PowerOn();
@@ -491,8 +491,23 @@ static void call_extension_command(struct tpm_cmd_header *tpmh,
 }
 #endif
 
+/*
+ * We need to be able to report firmware version to the host, both RO and RW
+ * sections. The first four bytes of the RO seciton's SHA are saved in the RO
+ * header, which is mapped into the beginning of flash memory.
+ */
+static void set_version_string(void)
+{
+	const struct SignedHeader *sh = (const struct SignedHeader *)
+		CONFIG_PROGRAM_MEMORY_BASE;
+
+	snprintf(tpm_fw_ver, sizeof(tpm_fw_ver), "RO: %08x RW: %s",
+		 sh->img_chk_, system_get_version(SYSTEM_IMAGE_RW));
+}
+
 void tpm_task(void)
 {
+	set_version_string();
 	tpm_init();
 	sps_tpm_enable();
 	while (1) {