From: Stefano Garzarella <sgarz...@redhat.com>
Some devices do not support interrupts and provide a single operation
to send the command and receive the response on the same buffer.
To support this scenario, a driver could set TPM_CHIP_FLAG_IRQ in the
chip's flags to get recv() to be called immediately after send() in
tpm_try_transmit(), or it needs to implement .status() to return 0,
and set both .req_complete_mask and .req_complete_val to 0.
In order to simplify these drivers and avoid temporary buffers to be
used between the .send() and .recv() callbacks, introduce a new callback
send_recv(). If that callback is defined, it is called in
tpm_try_transmit() to send the command and receive the response on
the same buffer in a single call.
Suggested-by: Jason Gunthorpe <j...@ziepe.ca>
Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
---
include/linux/tpm.h | 2 ++
drivers/char/tpm/tpm-interface.c | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 6c3125300c00..4e796b8726b5 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -88,6 +88,8 @@ struct tpm_class_ops {
bool (*req_canceled)(struct tpm_chip *chip, u8 status);
int (*recv) (struct tpm_chip *chip, u8 *buf, size_t len);
int (*send) (struct tpm_chip *chip, u8 *buf, size_t len);
+ int (*send_recv)(struct tpm_chip *chip, u8 *buf, size_t buf_len,
+ size_t cmd_len);
void (*cancel) (struct tpm_chip *chip);
u8 (*status) (struct tpm_chip *chip);
void (*update_timeouts)(struct tpm_chip *chip,
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index f62f7871edbd..7f4e01790352 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -82,6 +82,12 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void
*buf, size_t bufsiz)
return -E2BIG;
}
+ if (chip->ops->send_recv) {
+ rc = 0;
+ len = chip->ops->send_recv(chip, buf, bufsiz, count);
+ goto out_send_recv;
+ }
+
rc = chip->ops->send(chip, buf, count);
if (rc < 0) {
if (rc != -EPIPE)
@@ -124,6 +130,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void
*buf, size_t bufsiz)
out_recv:
len = chip->ops->recv(chip, buf, bufsiz);
+out_send_recv:
if (len < 0) {
rc = len;
dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
--
2.48.1
