tpm: use tpm_pcr_read_dev() in tpm_do_selftest()

Instead of a ad-hoc protocol message construction it is better to
call tpm_pcr_read_dev().
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>

drivers/char/tpm/tpm-interface.c

@@ -782,7 +782,7 @@ int tpm_do_selftest(struct tpm_chip *chip)
 	unsigned int loops;
 	unsigned int delay_msec = 100;
 	unsigned long duration;
-	struct tpm_cmd_t cmd;
+	u8 dummy[TPM_DIGEST_SIZE];
 
 	duration = tpm_calc_ordinal_duration(chip, TPM_ORD_CONTINUE_SELFTEST);
 
@@ -797,9 +797,8 @@ int tpm_do_selftest(struct tpm_chip *chip)
 
 	do {
 		/* Attempt to read a PCR value */
-		cmd.header.in = pcrread_header;
-		cmd.params.pcrread_in.pcr_idx = cpu_to_be32(0);
-		rc = tpm_transmit(chip, (u8 *) &cmd, READ_PCR_RESULT_SIZE, 0);
+		rc = tpm_pcr_read_dev(chip, 0, dummy);
+
 		/* Some buggy TPMs will not respond to tpm_tis_ready() for
 		 * around 300ms while the self test is ongoing, keep trying
 		 * until the self test duration expires. */
@@ -814,7 +813,6 @@ int tpm_do_selftest(struct tpm_chip *chip)
 		if (rc < TPM_HEADER_SIZE)
 			return -EFAULT;
 
-		rc = be32_to_cpu(cmd.header.out.return_code);
 		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
 			dev_info(&chip->dev,
 				 "TPM is disabled/deactivated (0x%X)\n", rc);