tpm: factor out tpm1_get_random into tpm1-cmd.c

Factor out get random implementation from tpm-interface.c
into tpm1_get_random function in tpm1-cmd.c.
No functional changes.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 3bd079587ef5..e02f0c1c822f 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -469,3 +469,58 @@ ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm1_getcap);
+
+#define TPM_ORD_GET_RANDOM 70
+#define TPM_GETRANDOM_RESULT_SIZE	18
+static const struct tpm_input_header tpm_getrandom_header = {
+	.tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
+	.length = cpu_to_be32(14),
+	.ordinal = cpu_to_be32(TPM_ORD_GET_RANDOM)
+};
+
+int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max)
+{
+	struct tpm_cmd_t tpm_cmd;
+	u32 recd;
+	u32 num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA);
+	u32 rlength;
+	int err, total = 0, retries = 5;
+	u8 *dest = out;
+
+	if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
+		return -EINVAL;
+
+	do {
+		tpm_cmd.header.in = tpm_getrandom_header;
+		tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
+
+		err = tpm_transmit_cmd(chip, NULL, &tpm_cmd,
+				       TPM_GETRANDOM_RESULT_SIZE + num_bytes,
+				       offsetof(struct tpm_getrandom_out,
+						rng_data),
+				       0, "attempting get random");
+		if (err)
+			break;
+
+		recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
+		if (recd > num_bytes) {
+			total = -EFAULT;
+			break;
+		}
+
+		rlength = be32_to_cpu(tpm_cmd.header.out.length);
+		if (rlength < TPM_HEADER_SIZE +
+			      offsetof(struct tpm_getrandom_out, rng_data) +
+			      recd) {
+			total = -EFAULT;
+			break;
+		}
+		memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
+
+		dest += recd;
+		total += recd;
+		num_bytes -= recd;
+	} while (retries-- && (size_t)total < max);
+
+	return total ? total : -EIO;
+}