0001 What: /sys/bus/css/devices/.../type
0002 Date: March 2008
0003 Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
0004 linux-s390@vger.kernel.org
0005 Description: Contains the subchannel type, as reported by the hardware.
0006 This attribute is present for all subchannel types.
0007
0008 What: /sys/bus/css/devices/.../modalias
0009 Date: March 2008
0010 Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
0011 linux-s390@vger.kernel.org
0012 Description: Contains the module alias as reported with uevents.
0013 It is of the format css:t<type> and present for all
0014 subchannel types.
0015
0016 What: /sys/bus/css/drivers/io_subchannel/.../chpids
0017 Date: December 2002
0018 Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
0019 linux-s390@vger.kernel.org
0020 Description: Contains the ids of the channel paths used by this
0021 subchannel, as reported by the channel subsystem
0022 during subchannel recognition.
0023
0024 Note: This is an I/O-subchannel specific attribute.
0025 Users: s390-tools, HAL
0026
0027 What: /sys/bus/css/drivers/io_subchannel/.../pimpampom
0028 Date: December 2002
0029 Contact: Cornelia Huck <cornelia.huck@de.ibm.com>
0030 linux-s390@vger.kernel.org
0031 Description: Contains the PIM/PAM/POM values, as reported by the
0032 channel subsystem when last queried by the common I/O
0033 layer (this implies that this attribute is not necessarily
0034 in sync with the values current in the channel subsystem).
0035
0036 Note: This is an I/O-subchannel specific attribute.
0037 Users: s390-tools, HAL
0038
0039 What: /sys/bus/css/devices/.../driver_override
0040 Date: June 2019
0041 Contact: Cornelia Huck <cohuck@redhat.com>
0042 linux-s390@vger.kernel.org
0043 Description: This file allows the driver for a device to be specified. When
0044 specified, only a driver with a name matching the value written
0045 to driver_override will have an opportunity to bind to the
0046 device. The override is specified by writing a string to the
0047 driver_override file (echo vfio-ccw > driver_override) and
0048 may be cleared with an empty string (echo > driver_override).
0049 This returns the device to standard matching rules binding.
0050 Writing to driver_override does not automatically unbind the
0051 device from its current driver or make any attempt to
0052 automatically load the specified driver. If no driver with a
0053 matching name is currently loaded in the kernel, the device
0054 will not bind to any driver. This also allows devices to
0055 opt-out of driver binding using a driver_override name such as
0056 "none". Only a single driver may be specified in the override,
0057 there is no support for parsing delimiters.
0058
0059 Note that unlike the mechanism of the same name for pci, this
0060 file does not allow to override basic matching rules. I.e.,
0061 the driver must still match the subchannel type of the device.
