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Diffstat (limited to 'Documentation/driver-api/s390-drivers.rst')
| -rw-r--r-- | Documentation/driver-api/s390-drivers.rst | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/Documentation/driver-api/s390-drivers.rst b/Documentation/driver-api/s390-drivers.rst index ecf8851d3565..30e6aa7e160b 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 =========== @@ -102,10 +121,15 @@ ccw group devices Generic interfaces ================== -Some interfaces are available to other drivers that do not necessarily -have anything to do with the busses described above, but still are -indirectly using basic infrastructure in the common I/O layer. One -example is the support for adapter interrupts. +The following section contains interfaces in use not only by drivers +dealing with ccw devices, but drivers for various other s390 hardware +as well. + +Adapter interrupts +------------------ + +The common I/O layer provides helper functions for dealing with adapter +interrupts and interrupt vectors. .. kernel-doc:: drivers/s390/cio/airq.c :export: |