Re: [PATCH v3 4/6] tpm: TPM 2.0 sysfs attributes

On Wed, Oct 15, 2014 at 4:35 AM, Jarkko Sakkinen
[off-list ref] wrote:

Implemented sysfs attributes for TPM2 devices. TPM2 sysfs attributes
are mounted in the actual device associated with the chip instead of
platform device like with TPM1 devices.

Documentation/ABI/stable/sysfs-class/tpm2 contains descriptions
of these attributes.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

+What:          /sys/class/misc/tpmX/device/cancel
+Date:          October 2014
+KernelVersion: 3.19
+Contact:       tpmdd-devel-TtF/mJH4Jtrk1uMJSBkQmQ@public.gmane.org
+Description:   The "cancel" property allows you to cancel the currently
+               pending TPM command. Writing any value to cancel will call the
+               TPM chip specific cancel operation.

This is weird.  From the POV of a sysfs user, what operation gets
canceled?  What if it's a kernel-internal operation?

Shouldn't this be an ioctl?

--Andy