On Wed, Mar 26, 2025 at 04:57:47PM +0200, Jarkko Sakkinen wrote:
> On Wed, Mar 26, 2025 at 11:34:01AM -0300, Jason Gunthorpe wrote:
> > On Wed, Mar 26, 2025 at 02:11:12PM +0200, Jarkko Sakkinen wrote:
> >
> > > Generally speaking I don't see enough value in complicating
> > > callback interface. It's better to handle complications in
> > > the leaves (i.e. dictatorship of majority ;-) ).
> >
> > That is very much not the way most driver subsystems view the
> > world. We want to pull logical things into the core code and remove
> > them from drivers to make the drivers simpler and more robust.
> >
> > The amount of really dumb driver boiler plate that this series
> > obviously removes is exactly the sort of stuff we should be fixing by
> > improving the core code.
> >
> > The callback interface was never really sanely designed, it was just
> > built around the idea of pulling the timout processing into the core
> > code for TIS hardware. It should be revised to properly match these
> > new HW types that don't have this kind of timeout mechanism.
>
> Both TIS and CRB, which are TCG standards and they span to many
> different types of drivers and busses. I don't have the figures but
> probably they cover vast majority of the hardware.
>
> We are talking about 39 lines of reduced complexity at the cost
> of complicating branching at the top level. I doubt that there
> is either any throughput or latency issues.
>
> What is measurable benefit? The rationale is way way too abstract
> for me to cope, sorry.
E.g., here's how you can get rid of extra cruft in tpm_ftpm_tee w/o
any new callbacks.
BR, Jarkko
>From 1125e80ea274a5ec5d5dba32bfce716ce62c5e4a Mon Sep 17 00:00:00 2001
From: Jarkko Sakkinen <jar...@kernel.org>
Date: Wed, 26 Mar 2025 17:55:49 +0200
Subject: [PATCH] tpm: Make chip->{status,cancel,req_canceled} opt
tpm_ftpm_tee does not require chip->status, chip->cancel and
chip->req_canceled. Make them optional.
Signed-off-by: Jarkko Sakkinen <jar...@kernel.org>
---
drivers/char/tpm/tpm-interface.c | 31 ++++++++++++++++++++++++++++---
drivers/char/tpm/tpm_ftpm_tee.c | 18 ------------------
2 files changed, 28 insertions(+), 21 deletions(-)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index f62f7871edbd..10ba47a882d8 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -58,6 +58,30 @@ unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
}
EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);
+static void tpm_chip_cancel(struct tpm_chip *chip)
+{
+ if (!chip->ops->cancel)
+ return;
+
+ chip->ops->cancel(chip);
+}
+
+static u8 tpm_chip_status(struct tpm_chip *chip)
+{
+ if (!chip->ops->status)
+ return 0;
+
+ return chip->ops->status(chip);
+}
+
+static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
+{
+ if (!chip->ops->req_canceled)
+ return false;
+
+ return chip->ops->req_canceled(chip, status);
+}
+
static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
{
struct tpm_header *header = buf;
@@ -65,6 +89,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
ssize_t len = 0;
u32 count, ordinal;
unsigned long stop;
+ u8 status;
if (bufsiz < TPM_HEADER_SIZE)
return -EINVAL;
@@ -104,12 +129,12 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
do {
- u8 status = chip->ops->status(chip);
+ status = tpm_chip_status(chip);
if ((status & chip->ops->req_complete_mask) ==
chip->ops->req_complete_val)
goto out_recv;
- if (chip->ops->req_canceled(chip, status)) {
+ if (tpm_chip_req_canceled(chip, status)) {
dev_err(&chip->dev, "Operation Canceled\n");
return -ECANCELED;
}
@@ -118,7 +143,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
rmb();
} while (time_before(jiffies, stop));
- chip->ops->cancel(chip);
+ tpm_chip_cancel(chip);
dev_err(&chip->dev, "Operation Timed out\n");
return -ETIME;
diff --git a/drivers/char/tpm/tpm_ftpm_tee.c b/drivers/char/tpm/tpm_ftpm_tee.c
index 8d9209dfc384..3732f3623537 100644
--- a/drivers/char/tpm/tpm_ftpm_tee.c
+++ b/drivers/char/tpm/tpm_ftpm_tee.c
@@ -164,30 +164,12 @@ static int ftpm_tee_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t len)
return 0;
}
-static void ftpm_tee_tpm_op_cancel(struct tpm_chip *chip)
-{
- /* not supported */
-}
-
-static u8 ftpm_tee_tpm_op_status(struct tpm_chip *chip)
-{
- return 0;
-}
-
-static bool ftpm_tee_tpm_req_canceled(struct tpm_chip *chip, u8 status)
-{
- return false;
-}
-
static const struct tpm_class_ops ftpm_tee_tpm_ops = {
.flags = TPM_OPS_AUTO_STARTUP,
.recv = ftpm_tee_tpm_op_recv,
.send = ftpm_tee_tpm_op_send,
- .cancel = ftpm_tee_tpm_op_cancel,
- .status = ftpm_tee_tpm_op_status,
.req_complete_mask = 0,
.req_complete_val = 0,
- .req_canceled = ftpm_tee_tpm_req_canceled,
};
/*
--
2.39.5
