even if they aren't actually driven by ccws.
All ccw devices are accessed via a subchannel, this is reflected in the
-structures under root/:
+structures under devices/:
-root/
- - sys
- - legacy
+devices/
+ - system/
- css0/
- 0.0.0000/0.0.0815/
- 0.0.0001/0.0.4711/
- 0.0.0002/
+ - 0.1.0000/0.1.1234/
...
+ - defunct/
-In this example, device 0815 is accessed via subchannel 0, device 4711 via
-subchannel 1, and subchannel 2 is a non-I/O subchannel.
+In this example, device 0815 is accessed via subchannel 0 in subchannel set 0,
+device 4711 via subchannel 1 in subchannel set 0, and subchannel 2 is a non-I/O
+subchannel. Device 1234 is accessed via subchannel 0 in subchannel set 1.
+
+The subchannel named 'defunct' does not represent any real subchannel on the
+system; it is a pseudo subchannel where disconnnected ccw devices are moved to
+if they are displaced by another ccw device becoming operational on their
+former subchannel. The ccw devices will be moved again to a proper subchannel
+if they become operational again on that subchannel.
You should address a ccw device via its bus id (e.g. 0.0.4711); the device can
be found under bus/ccw/devices/.
online: An interface to set the device online and offline.
In the special case of the device being disconnected (see the
- notify function under 1.2), piping 0 to online will focibly delete
+ notify function under 1.2), piping 0 to online will forcibly delete
the device.
The device drivers can add entries to export per-device data and interfaces.
Each driver should declare in a MODULE_DEVICE_TABLE into which CU types/models
and/or device types/models it is interested. This information can later be found
-found in the struct ccw_device_id fields:
+in the struct ccw_device_id fields:
struct ccw_device_id {
__u16 match_flags;
* In online state, device detached (CIO_GONE) or last path gone
(CIO_NO_PATH). The driver must return !0 to keep the device; for
return code 0, the device will be deleted as usual (also when no
- notify function is registerd). If the driver wants to keep the
+ notify function is registered). If the driver wants to keep the
device, it is moved into disconnected state.
* In disconnected state, device operational again (CIO_OPER). The
common I/O layer performs some sanity checks on device number and
again (only when offline). This is a generic ccwgroup mechanism (the driver does
not need to implement anything beyond normal removal routines).
+A ccw device which is a member of a ccwgroup device carries a pointer to the
+ccwgroup device in the driver_data of its device struct. This field must not be
+touched by the driver - it should use the ccwgroup device's driver_data for its
+private data.
+
To implement a ccwgroup driver, please refer to include/asm/ccwgroup.h. Keep in
mind that most drivers will need to implement both a ccwgroup and a ccw driver
(unless you have a meta ccw driver, like cu3088 for lcs and ctc).
Please note, that unlike /proc/chpids in 2.4, the channel path objects reflect
only the logical state and not the physical state, since we cannot track the
latter consistently due to lacking machine support (we don't need to be aware
-of anyway).
+of it anyway).
status - Can be 'online' or 'offline'.
Piping 'on' or 'off' sets the chpid logically online/offline.
a channel path the user knows to be online, but the machine hasn't
created a machine check for.
+type - The physical type of the channel path.
+
+shared - Whether the channel path is shared.
+
+cmg - The channel measurement group.
3. System devices
-----------------
-Note: cpus may yet be added here.
-
3.1 xpram
---------
-xpram shows up under sys/ as 'xpram'.
+xpram shows up under devices/system/ as 'xpram'.
+
+3.2 cpus
+--------
+
+For each cpu, a directory is created under devices/system/cpu/. Each cpu has an
+attribute 'online' which can be 0 or 1.
4. Other devices
-----------
The netiucv driver creates an attribute 'connection' under
-bus/iucv/drivers/netiucv. Piping to this attibute creates a new netiucv
+bus/iucv/drivers/netiucv. Piping to this attribute creates a new netiucv
connection to the specified host.
Netiucv connections show up under devices/iucv/ as "netiucv<ifnum>". The interface