refactor: use event log utils in linux tpm tests

Simplifies event log parsing by replacing manual expect patterns with
capture_log, compare_log, and capture_and_compare_log utility functions.
Improves maintainability and consistency across TPM scripts.

Change-Id: I4e3ad47189f4ace1b447d28313902e6e357235bf
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
diff --git a/expect/linux-tpm.exp b/expect/linux-tpm.exp
index 8aff8ce..e5d255c 100644
--- a/expect/linux-tpm.exp
+++ b/expect/linux-tpm.exp
@@ -11,33 +11,13 @@
 
 # File to store the event log from the ftpm service.
 set TFA_DIGEST [get_param tfa_digest "tfa_event_log"]
+set FTPM_DIGEST [get_param ftpm_digest "ftpm_event_log"]
 
 # regexp for non-zero PCR0
 set non_zero_pcr "(?!(\\s00){16})((\\s(\[0-9a-f\]){2}){16}\\s)"
 set zero_pcr "(\\s00){16}\\s+(00\\s){16}"
 
-expect {
-        # Wait for the start of the event log dump.
-        "TCG_EfiSpecIDEvent:" {
-                set digest_log [open $TFA_DIGEST w]
-        }
-}
-
-expect {
-        # Parse the event log from the debug logs and store the digests
-        # so they can be matched later with what the fTPM reads.
-
-        -re "Digest(\\s|\\w)*:\\s(\\w{2}\\s){16}|\
-        : (\\w{2}\\s){16}|\
-        Event(\\s|\\w)*:\\s\\w+\\s" {
-                puts $digest_log $expect_out(0,string)
-                exp_continue
-        }
-
-        -exact "Booting BL31" {
-                close $digest_log
-        }
-}
+capture_log $TFA_DIGEST "Booting BL31"
 
 expect {
         "login" {
@@ -90,12 +70,4 @@
 
 expect_string "#" "finished reading PCRs"
 
-# Match the previously stored digest with the one generated by the
-# fTPM service. The pass criteria is that both digests must match,
-# meaning that TF-A successfully passed the event log to the TPM service.
-if {[catch {exec diff -s $TFA_DIGEST ftpm_event_log} result options] == 0} {
-        message "tests succeeded, digests matched"
-} else {
-        message "tests failed, digests did not match"
-        exit_uart -1
-}
+compare_log $TFA_DIGEST $FTPM_DIGEST
\ No newline at end of file