[PATCH] tpm: Add major_version sysfs file

[Jerry Snitselaar]

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.

Cc: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Cc: Peter Huewe <peterhuewe@xxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: linux-integrity@xxxxxxxxxxxxxxx
Signed-off-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
---
 drivers/char/tpm/tpm-sysfs.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index edfa89160010..9372c2d6f0b3 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, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(timeouts);
 
-static struct attribute *tpm_dev_attrs[] = {
+static ssize_t major_version_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct tpm_chip *chip = to_tpm_chip(dev);
+
+	return sprintf(buf, "%s\n", chip->flags & TPM_CHIP_FLAG_TPM2
+		       ? "2.0" : "1.2");
+}
+static DEVICE_ATTR_RO(major_version);
+
+static struct attribute *tpm12_dev_attrs[] = {
 	&dev_attr_pubek.attr,
 	&dev_attr_pcrs.attr,
 	&dev_attr_enabled.attr,
@@ -320,18 +330,28 @@ static struct attribute *tpm_dev_attrs[] = {
 	&dev_attr_cancel.attr,
 	&dev_attr_durations.attr,
 	&dev_attr_timeouts.attr,
+	&dev_attr_major_version.attr,
 	NULL,
 };
 
-static const struct attribute_group tpm_dev_group = {
-	.attrs = tpm_dev_attrs,
+static struct attribute *tpm20_dev_attrs[] = {
+	&dev_attr_major_version.attr,
+	NULL
+};
+
+static const struct attribute_group tpm12_dev_group = {
+	.attrs = tpm12_dev_attrs,
+};
+
+static const struct attribute_group tpm20_dev_group = {
+	.attrs = tpm20_dev_attrs,
 };
 
 void tpm_sysfs_add_device(struct tpm_chip *chip)
 {
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		return;
-
 	WARN_ON(chip->groups_cnt != 0);
-	chip->groups[chip->groups_cnt++] = &tpm_dev_group;
+	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+		chip->groups[chip->groups_cnt++] = &tpm20_dev_group;
+	else
+		chip->groups[chip->groups_cnt++] = &tpm12_dev_group;
 }
-- 
2.23.0