[v3,1/4] tpm: Add a flag to indicate TPM power is managed by firmware
diff mbox series

Message ID 20190806220750.86597-2-swboyd@chromium.org
State New
Headers show
Series
  • tpm: Add driver for cr50
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Commit Message

Stephen Boyd Aug. 6, 2019, 10:07 p.m. UTC
On some platforms, the TPM power is managed by firmware and therefore we
don't need to stop the TPM on suspend when going to a light version of
suspend such as S0ix ("freeze" suspend state). Add a chip flag to
indicate this so that certain platforms can probe for the usage of this
light suspend and avoid touching the TPM state across suspend/resume.

Cc: Andrey Pronin <apronin@chromium.org>
Cc: Duncan Laurie <dlaurie@chromium.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Alexander Steffen <Alexander.Steffen@infineon.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
 drivers/char/tpm/tpm-interface.c | 8 +++++++-
 drivers/char/tpm/tpm.h           | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

Comments

Jarkko Sakkinen Aug. 9, 2019, 6:02 p.m. UTC | #1
On Tue, 2019-08-06 at 15:07 -0700, Stephen Boyd wrote:
> On some platforms, the TPM power is managed by firmware and therefore we
> don't need to stop the TPM on suspend when going to a light version of
> suspend such as S0ix ("freeze" suspend state). Add a chip flag to
> indicate this so that certain platforms can probe for the usage of this
> light suspend and avoid touching the TPM state across suspend/resume.

The commit message should mention the new constant.

> +	if (chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED)
> +		if (!pm_suspend_via_firmware())

Why both checks are needed?

If both checks are needed, you could write it as a single
conditional statement:

if (chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED &&
    !pm_suspend_via_firmware())

/Jarkko
Stephen Boyd Aug. 12, 2019, 2:11 p.m. UTC | #2
Quoting Jarkko Sakkinen (2019-08-09 11:02:01)
> On Tue, 2019-08-06 at 15:07 -0700, Stephen Boyd wrote:
> > On some platforms, the TPM power is managed by firmware and therefore we
> > don't need to stop the TPM on suspend when going to a light version of
> > suspend such as S0ix ("freeze" suspend state). Add a chip flag to
> > indicate this so that certain platforms can probe for the usage of this
> > light suspend and avoid touching the TPM state across suspend/resume.
> 
> The commit message should mention the new constant.

Alright.

> 
> > +     if (chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED)
> > +             if (!pm_suspend_via_firmware())
> 
> Why both checks are needed?
> 
> If both checks are needed, you could write it as a single
> conditional statement:
> 
> if (chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED &&
>     !pm_suspend_via_firmware())
> 

Ok. I'll combine them.

Patch
diff mbox series

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1b4f95c13e00..9bf3ddee6c8c 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -23,6 +23,7 @@ 
 #include <linux/slab.h>
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
+#include <linux/suspend.h>
 #include <linux/freezer.h>
 #include <linux/tpm_eventlog.h>
 
@@ -395,7 +396,11 @@  int tpm_pm_suspend(struct device *dev)
 		return -ENODEV;
 
 	if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
-		return 0;
+		goto suspended;
+
+	if (chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED)
+		if (!pm_suspend_via_firmware())
+			goto suspended;
 
 	if (!tpm_chip_start(chip)) {
 		if (chip->flags & TPM_CHIP_FLAG_TPM2)
@@ -406,6 +411,7 @@  int tpm_pm_suspend(struct device *dev)
 		tpm_chip_stop(chip);
 	}
 
+suspended:
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm_pm_suspend);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index e503ffc3aa39..28f73331aa2e 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -162,6 +162,7 @@  enum tpm_chip_flags {
 	TPM_CHIP_FLAG_VIRTUAL		= BIT(3),
 	TPM_CHIP_FLAG_HAVE_TIMEOUTS	= BIT(4),
 	TPM_CHIP_FLAG_ALWAYS_POWERED	= BIT(5),
+	TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED	= BIT(6),
 };
 
 #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)