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

Jarkko Sakkinen
2018-03-26T12:14:04Z

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.sakkinen@linux.intel.com>
Acked-by: Jay Freyensee <why2jjj.linux@gmail.com>
---
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);
--
2.15.1