tpm: Introduce TPM_CHIP_FLAG_VIRTUAL

Introduce TPM_CHIP_FLAG_VIRTUAL to be used when the chip device has no
parent device.

Prevent sysfs entries requiring a parent device from being created.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

drivers/char/tpm/tpm-chip.c

@@ -181,6 +181,9 @@ struct tpm_chip *tpm_chip_alloc(struct device *dev,
 	if (rc)
 		goto out;
 
+	if (!dev)
+		chip->flags |= TPM_CHIP_FLAG_VIRTUAL;
+
 	cdev_init(&chip->cdev, &tpm_fops);
 	chip->cdev.owner = THIS_MODULE;
 	chip->cdev.kobj.parent = &chip->dev.kobj;
@@ -298,7 +301,7 @@ static void tpm_del_legacy_sysfs(struct tpm_chip *chip)
 {
 	struct attribute **i;
 
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+	if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
 		return;
 
 	sysfs_remove_link(&chip->dev.parent->kobj, "ppi");
@@ -316,7 +319,7 @@ static int tpm_add_legacy_sysfs(struct tpm_chip *chip)
 	struct attribute **i;
 	int rc;
 
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+	if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
 		return 0;
 
 	rc = __compat_only_sysfs_link_entry_to_kobj(

drivers/char/tpm/tpm.h

@@ -138,6 +138,7 @@ enum tpm_chip_flags {
 	TPM_CHIP_FLAG_REGISTERED	= BIT(0),
 	TPM_CHIP_FLAG_TPM2		= BIT(1),
 	TPM_CHIP_FLAG_IRQ		= BIT(2),
+	TPM_CHIP_FLAG_VIRTUAL		= BIT(3),
 };
 
 struct tpm_chip {