linux-kernel - [PATCH v6 2/4] tpm: Add a flag to indicate TPM power is managed by firmware

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Message-Id: <20190829224110.91103-3-swboyd@chromium.org>
Date:   Thu, 29 Aug 2019 15:41:08 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        Andrey Pronin <apronin@...omium.org>,
        Duncan Laurie <dlaurie@...omium.org>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <groeck@...omium.org>,
        Alexander Steffen <Alexander.Steffen@...ineon.com>,
        Heiko Stuebner <heiko@...ech.de>
Subject: [PATCH v6 2/4] tpm: Add a flag to indicate TPM power is managed by firmware

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,
TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED, 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@...omium.org>
Cc: Duncan Laurie <dlaurie@...omium.org>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Guenter Roeck <groeck@...omium.org>
Cc: Alexander Steffen <Alexander.Steffen@...ineon.com>
Cc: Heiko Stuebner <heiko@...ech.de>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Signed-off-by: Stephen Boyd <swboyd@...omium.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..0b3def8e8186 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) &&
+	    !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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