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From:   Jerry Snitselaar <jsnitsel@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Peter Huewe <peterhuewe@gmx.de>,
        Jason Gunthorpe <jgg@ziepe.ca>, linux-integrity@vger.kernel.org
Subject: [PATCH v3] tpm: Add version_major sysfs file
Date:   Sun, 27 Oct 2019 11:38:00 -0700
Message-Id: <20191027183800.11824-1-jsnitsel@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Easily determining what TCG version a tpm device implements
has been a pain point for userspace for a long time, so
add a sysfs file to report the TCG version of a tpm device.

Also add an entry to Documentation/ABI/stable/sysfs-class-tpm
describing the new file.

Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Peter Huewe <peterhuewe@gmx.de>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-integrity@vger.kernel.org
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
---
v3: - Change file name to version_major.
v2: - Fix TCG usage in commit message.
    - Add entry to sysfs-class-tpm in Documentation/ABI/stable

 Documentation/ABI/stable/sysfs-class-tpm | 11 ++++++++
 drivers/char/tpm/tpm-sysfs.c             | 34 +++++++++++++++++++-----
 2 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/stable/sysfs-class-tpm b/Documentation/ABI/s=
table/sysfs-class-tpm
index c0e23830f56a..116f8d3a8ddc 100644
--- a/Documentation/ABI/stable/sysfs-class-tpm
+++ b/Documentation/ABI/stable/sysfs-class-tpm
@@ -183,3 +183,14 @@ Description:=09The "timeouts" property shows the 4 ven=
dor-specific values
 =09=09The four timeout values are shown in usecs, with a trailing
 =09=09"[original]" or "[adjusted]" depending on whether the values
 =09=09were scaled by the driver to be reported in usec from msecs.
+
+What:=09=09/sys/class/tpm/tpmX/version_major
+Date:=09=09October 2019
+KernelVersion:=095.5
+Contact:=09linux-integrity@vger.kernel.org
+Description:=09The "version_major" property shows the TCG spec version
+=09=09implemented by the TPM device.
+
+=09=09Example output:
+
+=09=092.0
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index edfa89160010..6993ef00f256 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -309,7 +309,17 @@ static ssize_t timeouts_show(struct device *dev, struc=
t device_attribute *attr,
 }
 static DEVICE_ATTR_RO(timeouts);
=20
-static struct attribute *tpm_dev_attrs[] =3D {
+static ssize_t version_major_show(struct device *dev,
+=09=09=09=09  struct device_attribute *attr, char *buf)
+{
+=09struct tpm_chip *chip =3D to_tpm_chip(dev);
+
+=09return sprintf(buf, "%s\n", chip->flags & TPM_CHIP_FLAG_TPM2
+=09=09       ? "2.0" : "1.2");
+}
+static DEVICE_ATTR_RO(version_major);
+
+static struct attribute *tpm12_dev_attrs[] =3D {
 =09&dev_attr_pubek.attr,
 =09&dev_attr_pcrs.attr,
 =09&dev_attr_enabled.attr,
@@ -320,18 +330,28 @@ static struct attribute *tpm_dev_attrs[] =3D {
 =09&dev_attr_cancel.attr,
 =09&dev_attr_durations.attr,
 =09&dev_attr_timeouts.attr,
+=09&dev_attr_version_major.attr,
 =09NULL,
 };
=20
-static const struct attribute_group tpm_dev_group =3D {
-=09.attrs =3D tpm_dev_attrs,
+static struct attribute *tpm20_dev_attrs[] =3D {
+=09&dev_attr_version_major.attr,
+=09NULL
+};
+
+static const struct attribute_group tpm12_dev_group =3D {
+=09.attrs =3D tpm12_dev_attrs,
+};
+
+static const struct attribute_group tpm20_dev_group =3D {
+=09.attrs =3D tpm20_dev_attrs,
 };
=20
 void tpm_sysfs_add_device(struct tpm_chip *chip)
 {
-=09if (chip->flags & TPM_CHIP_FLAG_TPM2)
-=09=09return;
-
 =09WARN_ON(chip->groups_cnt !=3D 0);
-=09chip->groups[chip->groups_cnt++] =3D &tpm_dev_group;
+=09if (chip->flags & TPM_CHIP_FLAG_TPM2)
+=09=09chip->groups[chip->groups_cnt++] =3D &tpm20_dev_group;
+=09else
+=09=09chip->groups[chip->groups_cnt++] =3D &tpm12_dev_group;
 }
--=20
2.23.0