/**
+ * tpm_transmit - Internal kernel interface to transmit TPM commands.
+ *
+ * @chip: TPM chip to use
+ * @space: tpm space
+ * @buf: TPM command buffer
+ * @bufsiz: length of the TPM command buffer
+ * @flags: tpm transmit flags - bitmap
+ *
+ * A wrapper around tpm_try_transmit that handles TPM2_RC_RETRY
+ * returns from the TPM and retransmits the command after a delay up
+ * to a maximum wait of TPM2_DURATION_LONG.
+ *
+ * Note: TPM1 never returns TPM2_RC_RETRY so the retry logic is TPM2
+ * only
+ *
+ * Return:
+ * the length of the return when the operation is successful.
+ * A negative number for system errors (errno).
+ */
+ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
+ u8 *buf, size_t bufsiz, unsigned int flags)
+{
+ struct tpm_output_header *header = (struct tpm_output_header *)buf;
+ /* space for header and handles */
+ u8 save[TPM_HEADER_SIZE + 3*sizeof(u32)];
+ unsigned int delay_msec = TPM2_DURATION_SHORT;
+ u32 rc = 0;
+ ssize_t ret;
+ const size_t save_size = min(space ? sizeof(save) : TPM_HEADER_SIZE,
+ bufsiz);
+
+ /*
+ * Subtlety here: if we have a space, the handles will be
+ * transformed, so when we restore the header we also have to
+ * restore the handles.
+ */
+ memcpy(save, buf, save_size);
+
+ for (;;) {
+ ret = tpm_try_transmit(chip, space, buf, bufsiz, flags);
+ if (ret < 0)
+ break;
+ rc = be32_to_cpu(header->return_code);
+ if (rc != TPM2_RC_RETRY)
+ break;
+ delay_msec *= 2;
Was wondering if this increment could be moved after
tpm_msleep(delay_msec) ?
Thanks & Regards,
- Nayna
+ if (delay_msec > TPM2_DURATION_LONG) {
+ dev_err(&chip->dev, "TPM is in retry loop\n");
+ break;
+ }
+ tpm_msleep(delay_msec);
+ memcpy(buf, save, save_size);
+ }
+ return ret;
+}
+/**
* tpm_transmit_cmd - send a tpm command to the device
* The function extracts tpm out header return code
*
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index ab3861631d27..05967c1a1f32 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -112,6 +112,7 @@ enum tpm2_return_codes {
TPM2_RC_COMMAND_CODE = 0x0143,
TPM2_RC_TESTING = 0x090A, /* RC_WARN */
TPM2_RC_REFERENCE_H0 = 0x0910,
+ TPM2_RC_RETRY = 0x0922,
};
enum tpm2_algorithms {
