From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752200AbeAWPC6 (ORCPT ); Tue, 23 Jan 2018 10:02:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48190 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752041AbeAWPCy (ORCPT ); Tue, 23 Jan 2018 10:02:54 -0500 From: Cornelia Huck To: schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com Cc: corbet@lwn.net, sebott@linux.vnet.ibm.com, oberpar@linux.vnet.ibm.com, linux-s390@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Cornelia Huck Subject: [PATCH 1/3] s390/docs: mention subchannel types Date: Tue, 23 Jan 2018 16:02:43 +0100 Message-Id: <20180123150245.30312-2-cohuck@redhat.com> In-Reply-To: <20180123150245.30312-1-cohuck@redhat.com> References: <20180123150245.30312-1-cohuck@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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