On Mon, Mar 03, 2025 at 08:06:43AM -0600, Tom Lendacky wrote:
On 2/28/25 11:07, Stefano Garzarella wrote: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(). Instead of abusing TPM_CHIP_FLAG_IRQ, 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 <jgg@xxxxxxxx> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> --- include/linux/tpm.h | 2 ++ drivers/char/tpm/tpm-interface.c | 8 +++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 20a40ade8030..2ede8e0592d3 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 to_send); 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 b1daa0d7b341..4f92b0477696 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -82,6 +82,9 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) return -E2BIG; } + if (chip->ops->send_recv) + goto out_recv;It might look a bit cleaner if you issue the send_recv() call here and then jump to a new label after the recv() call just before 'len' is checked.
Yep, I see, I was undecided to avoid adding a new label and just have out_recv which in future cases always handles the send_recv() case.
But maybe I overthought, I will do as you suggest. Thanks, Stefano
Thanks, Tom+ rc = chip->ops->send(chip, buf, count); if (rc < 0) { if (rc != -EPIPE) @@ -123,7 +126,10 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz) return -ETIME; out_recv: - len = chip->ops->recv(chip, buf, bufsiz); + if (chip->ops->send_recv) + len = chip->ops->send_recv(chip, buf, bufsiz, count); + else + len = chip->ops->recv(chip, buf, bufsiz); if (len < 0) { rc = len; dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
