cr50: provide platform API for fw version capability

The tpm is supposed to report its firmware version when
TPM_PT_FIRMWARE_VERSION_1 and TPM_PT_FIRMWARE_VERSION_2 capabilities
are requested.

This patch retrieves form the build info string SHA1s of the ec and
tpm2 repositories and returns them to the caller.

BRANCH=none
BUG=chrome-os-partner:58177
TEST=with the appropriate tpm2 source tree changes the ec and tpm
      SHA1s are now reported:

    localhost ~ # tpm_version
    TPM 2.0 Version Info:
    Chip Version:        2.0.0.0
    ....
    Firmware Version:    0a92ec7c01b9c924

    (the first half is the zero prepended 7 characters of the ec SHA1,
    and the second half is the zero prepended 7 characters of the tpm2
    SHA1).

Change-Id: I01e4fffdafbbdc4668342ea511ca9c4a555e20a9
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/403115
Reviewed-by: Andrey Pronin <apronin@chromium.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/board/cr50/tpm2/platform.c b/board/cr50/tpm2/platform.c
index 20b5854625..7c98c353a0 100644
--- a/board/cr50/tpm2/platform.c
+++ b/board/cr50/tpm2/platform.c
@@ -7,6 +7,8 @@
 #include "TPM_Types.h"
 
 #include "trng.h"
+#include "util.h"
+#include "version.h"
 
 uint16_t _cpri__GenerateRandom(size_t random_size,
 			uint8_t *buffer)
@@ -14,3 +16,47 @@ uint16_t _cpri__GenerateRandom(size_t random_size,
 	rand_bytes(buffer, random_size);
 	return random_size;
 }
+
+/*
+ * Return the pointer to the character immediately after the first dash
+ * encountered in the passed in string, or NULL if there is no dashes in the
+ * string.
+ */
+static const char *char_after_dash(const char *str)
+{
+	char c;
+
+	do {
+		c = *str++;
+
+		if (c == '-')
+			return str;
+	} while (c);
+
+	return NULL;
+}
+
+/*
+ * The properly formatted build_info string has the ec code SHA1 after the
+ * first dash, and tpm2 code sha1 after the second dash.
+ */
+
+void   _plat__GetFwVersion(uint32_t *firmwareV1, uint32_t *firmwareV2)
+{
+	const char *ver_str = char_after_dash(build_info);
+
+	/* Just in case the build_info string is misformatted. */
+	*firmwareV1 = 0;
+	*firmwareV2 = 0;
+
+	if (!ver_str)
+		return;
+
+	*firmwareV1 = strtoi(ver_str, NULL, 16);
+
+	ver_str = char_after_dash(ver_str);
+	if (!ver_str)
+		return;
+
+	*firmwareV2 = strtoi(ver_str, NULL, 16);
+}