Re: [PATCH v4 2/4] tpm: migrate tpm2_probe() to use struct tpm_buf

[Nayna Jain]

On 03/26/2018 05:44 PM, Jarkko Sakkinen wrote:

In order to make struct tpm_buf the first class object for constructing TPM
commands, migrate tpm2_probe() to use it.

Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
Acked-by: Jay Freyensee <why2jjj.li...@gmail.com>

Reviewed-by: Nayna Jain<na...@linux.vnet.ibm.com>
Tested-by: Nayna Jain<na...@linux.vnet.ibm.com>


Thanks & Regards,
    - Nayna

---
  drivers/char/tpm/tpm2-cmd.c | 37 +++++++++++++++++++++----------------
  1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 7665661d9230..7bffd0fd1dca 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -844,30 +844,35 @@ static int tpm2_do_selftest(struct tpm_chip *chip)

  /**
   * tpm2_probe() - probe TPM 2.0
- * @chip: TPM chip to use
+ * @chip: a TPM chip to probe
   *
- * Return: < 0 error and 0 on success.
+ * Return: 0 on success,
+ *         -errno otherwise
   *
- * Send idempotent TPM 2.0 command and see whether TPM 2.0 chip replied based 
on
- * the reply tag.
+ * Send an idempotent TPM 2.0 command and see whether there is TPM2 chip in the
+ * other end based on the response tag. The flag TPM_CHIP_FLAG_TPM2 is set if
+ * this is the case.
   */
  int tpm2_probe(struct tpm_chip *chip)
  {
-       struct tpm2_cmd cmd;
+       struct tpm_output_header *out;
+       struct tpm_buf buf;
        int rc;

-       cmd.header.in = tpm2_get_tpm_pt_header;
-       cmd.params.get_tpm_pt_in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
-       cmd.params.get_tpm_pt_in.property_id = cpu_to_be32(0x100);
-       cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
-
-       rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0, 0, NULL);
-       if (rc <  0)
+       rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+       if (rc)
                return rc;
-
-       if (be16_to_cpu(cmd.header.out.tag) == TPM2_ST_NO_SESSIONS)
-               chip->flags |= TPM_CHIP_FLAG_TPM2;
-
+       tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
+       tpm_buf_append_u32(&buf, TPM_PT_TOTAL_COMMANDS);
+       tpm_buf_append_u32(&buf, 1);
+       rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE, 0, 0, NULL);
+       /* We ignore TPM return codes on purpose. */
+       if (rc >=  0) {
+               out = (struct tpm_output_header *)buf.data;
+               if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
+                       chip->flags |= TPM_CHIP_FLAG_TPM2;
+       }
+       tpm_buf_destroy(&buf);
        return 0;
  }
  EXPORT_SYMBOL_GPL(tpm2_probe);