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: Cornelia Huck <cohuck@xxxxxxxxxx> --- Documentation/driver-api/s390-drivers.rst | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/Documentation/driver-api/s390-drivers.rst b/Documentation/driver-api/s390-drivers.rst index ecf8851d3565..42350f21357d 100644 --- a/Documentation/driver-api/s390-drivers.rst +++ b/Documentation/driver-api/s390-drivers.rst @@ -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 =========== -- 2.13.6 -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
