Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7ddd0913 authored by Cornelia Huck's avatar Cornelia Huck Committed by Martin Schwidefsky
Browse files

s390/docs: mention subchannel types 



Since the original inception of the s390-drivers document, the
common I/O layer has grown support for more types of subchannels.
Give at least a pointer for the various types.

Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent f3ea8419

Documentation/driver-api/s390-drivers.rst

+19 −0
Original line number Diff line number Diff line
@@ -22,9 +22,28 @@ While most I/O devices on a s390 system are typically driven through the 
channel I/O mechanism described here, there are various other methods

(like the diag interface). These are out of the scope of this document.



The s390 common I/O layer also provides access to some devices that are

not strictly considered I/O devices. They are considered here as well,

although they are not the focus of this document.



Some additional information can also be found in the kernel source under

Documentation/s390/driver-model.txt.



The css bus

===========



The css bus contains the subchannels available on the system. They fall

into several categories:



* Standard I/O subchannels, for use by the system. They have a child

  device on the ccw bus and are described below.

* I/O subchannels bound to the vfio-ccw driver. See

  Documentation/s390/vfio-ccw.txt.

* Message subchannels. No Linux driver currently exists.

* CHSC subchannels (at most one). The chsc subchannel driver can be used

  to send asynchronous chsc commands.

* eADM subchannels. Used for talking to storage class memory.



The ccw bus

===========