1What:		/sys/bus/css/devices/.../type
2Date:		March 2008
3Contact:	Cornelia Huck <cornelia.huck@de.ibm.com>
4		linux-s390@vger.kernel.org
5Description:	Contains the subchannel type, as reported by the hardware.
6		This attribute is present for all subchannel types.
7
8What:		/sys/bus/css/devices/.../modalias
9Date:		March 2008
10Contact:	Cornelia Huck <cornelia.huck@de.ibm.com>
11		linux-s390@vger.kernel.org
12Description:	Contains the module alias as reported with uevents.
13		It is of the format css:t<type> and present for all
14		subchannel types.
15
16What:		/sys/bus/css/drivers/io_subchannel/.../chpids
17Date:		December 2002
18Contact:	Cornelia Huck <cornelia.huck@de.ibm.com>
19		linux-s390@vger.kernel.org
20Description:	Contains the ids of the channel paths used by this
21		subchannel, as reported by the channel subsystem
22		during subchannel recognition.
23
24		Note: This is an I/O-subchannel specific attribute.
25Users:		s390-tools, HAL
26
27What:		/sys/bus/css/drivers/io_subchannel/.../pimpampom
28Date:		December 2002
29Contact:	Cornelia Huck <cornelia.huck@de.ibm.com>
30		linux-s390@vger.kernel.org
31Description:	Contains the PIM/PAM/POM values, as reported by the
32		channel subsystem when last queried by the common I/O
33		layer (this implies that this attribute is not necessarily
34		in sync with the values current in the channel subsystem).
35
36		Note: This is an I/O-subchannel specific attribute.
37Users:		s390-tools, HAL
38
39What:		/sys/bus/css/devices/.../driver_override
40Date:		June 2019
41Contact:	Cornelia Huck <cohuck@redhat.com>
42		linux-s390@vger.kernel.org
43Description:	This file allows the driver for a device to be specified. When
44		specified, only a driver with a name matching the value written
45		to driver_override will have an opportunity to bind to the
46		device. The override is specified by writing a string to the
47		driver_override file (echo vfio-ccw > driver_override) and
48		may be cleared with an empty string (echo > driver_override).
49		This returns the device to standard matching rules binding.
50		Writing to driver_override does not automatically unbind the
51		device from its current driver or make any attempt to
52		automatically load the specified driver.  If no driver with a
53		matching name is currently loaded in the kernel, the device
54		will not bind to any driver.  This also allows devices to
55		opt-out of driver binding using a driver_override name such as
56		"none".  Only a single driver may be specified in the override,
57		there is no support for parsing delimiters.
58
59		Note that unlike the mechanism of the same name for pci, this
60		file does not allow to override basic matching rules. I.e.,
61		the driver must still match the subchannel type of the device.
62