[PATCH v3 1/4] tpm: Add a flag to indicate TPM power is managed by firmware

[Stephen Boyd]

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 <apro...@chromium.org>
Cc: Duncan Laurie <dlau...@chromium.org>
Cc: Jason Gunthorpe <j...@ziepe.ca>
Cc: Arnd Bergmann <a...@arndb.de>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Guenter Roeck <gro...@chromium.org>
Cc: Alexander Steffen <alexander.stef...@infineon.com>
Signed-off-by: Stephen Boyd <swb...@chromium.org>
---
 drivers/char/tpm/tpm-interface.c | 8 +++++++-
 drivers/char/tpm/tpm.h           | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

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)
-- 
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