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tpm: Call cmd_ready/go_idle for each command transmission

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Some TPM implementations, particularly fTPM using the CRB interface,
require the TPM to transition through idle and ready states for each
command rather than once per session.

The current implementation calls cmd_ready once during tpm_chip_start()
and go_idle once during tpm_chip_stop(). For fTPM, when multiple commands
are sent without per-command idle transitions, subsequent commands timeout
as the TPM is waiting for the transition.

Fix this by calling cmd_ready before each command and go_idle on all exit
paths in tpm_try_transmit(). For TPM implementations that don't require
per-command transitions, the callbacks return immediately based on the
start method.

Remove the now-redundant per-session calls from tpm_chip_start() and
tpm_chip_stop() along with their helpers.

This resolves timeout errors during TPM initialization on systems where
BIOS has already performed TPM startup.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20260901213723.3017371-1-mario.limonciello@amd.com
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
This commit is contained in:
Mario Limonciello 2026-09-01 16:37:22 -05:00 committed by Jarkko Sakkinen
parent 6fc1b05077
commit 313acd594a
2 changed files with 22 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
drivers/char/tpm/tpm-chip.c
View File

@ -66,22 +66,6 @@ static void tpm_relinquish_locality(struct tpm_chip *chip)
chip->locality = -1;
}
static int tpm_cmd_ready(struct tpm_chip *chip)
{
if (!chip->ops->cmd_ready)
return 0;
return chip->ops->cmd_ready(chip);
}
static int tpm_go_idle(struct tpm_chip *chip)
{
if (!chip->ops->go_idle)
return 0;
return chip->ops->go_idle(chip);
}
static void tpm_clk_enable(struct tpm_chip *chip)
{
if (chip->ops->clk_enable)
@ -116,13 +100,6 @@ int tpm_chip_start(struct tpm_chip *chip)
}
}
ret = tpm_cmd_ready(chip);
if (ret) {
tpm_relinquish_locality(chip);
tpm_clk_disable(chip);
return ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(tpm_chip_start);
@ -137,7 +114,6 @@ EXPORT_SYMBOL_GPL(tpm_chip_start);
*/
void tpm_chip_stop(struct tpm_chip *chip)
{
tpm_go_idle(chip);
tpm_relinquish_locality(chip);
tpm_clk_disable(chip);
}

22
drivers/char/tpm/tpm-interface.c
View File

@ -19,6 +19,7 @@
* calls to msleep.
*/
#include <linux/cleanup.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mutex.h>
@ -89,8 +90,17 @@ static bool tpm_transmit_completed(u8 status, struct tpm_chip *chip)
return status_masked == chip->ops->req_complete_val;
}
static void tpm_go_idle(struct tpm_chip *chip)
{
if (chip->ops->go_idle)
chip->ops->go_idle(chip);
}
DEFINE_FREE(tpm_go_idle, struct tpm_chip *, if (_T) tpm_go_idle(_T))
static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
{
struct tpm_chip *chip_idle __free(tpm_go_idle) = NULL;
struct tpm_header *header = buf;
int rc;
ssize_t len = 0;
@ -113,6 +123,18 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
return -E2BIG;
}
if (chip->ops->cmd_ready) {
rc = chip->ops->cmd_ready(chip);
if (rc) {
dev_err(&chip->dev,
"%s: cmd_ready(): error %d\n", __func__, rc);
return rc;
}
}
/* Ensure go_idle() is called on every exit path from here on. */
chip_idle = chip;
rc = chip->ops->send(chip, buf, bufsiz, count);
if (rc < 0) {
if (rc != -EPIPE)