path: root/Documentation/s390/driver-model.txt
diff options
authorCornelia Huck <>2006-03-24 03:15:13 -0800
committerLinus Torvalds <>2006-03-24 07:33:15 -0800
commitdc06010c62da773321258df1d8a1708a3158e29d (patch)
tree5f1981646537980d92e7c0ccc24867dfe116307e /Documentation/s390/driver-model.txt
parent3ba1998e90239ed0d7af918998bc866fa77303eb (diff)
[PATCH] s390: cio documentation update
Update documentation of the common I/O layer: - Add MSS-specific example. - Add more information on ccwgroup devices. - Add channel path type attribute. - Fix typo. Signed-off-by: Cornelia Huck <> Signed-off-by: Martin Schwidefsky <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'Documentation/s390/driver-model.txt')
1 files changed, 12 insertions, 3 deletions
diff --git a/Documentation/s390/driver-model.txt b/Documentation/s390/driver-model.txt
index df09758bf3fe..efb674eda4d4 100644
--- a/Documentation/s390/driver-model.txt
+++ b/Documentation/s390/driver-model.txt
@@ -16,10 +16,12 @@ devices/
- 0.0.0000/0.0.0815/
- 0.0.0001/0.0.4711/
- 0.0.0002/
+ - 0.1.0000/0.1.1234/
-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.
You should address a ccw device via its bus id (e.g. 0.0.4711); the device can
be found under bus/ccw/devices/.
@@ -97,7 +99,7 @@ is not available to the device driver.
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;
@@ -208,6 +210,11 @@ Each ccwgroup device also provides an 'ungroup' attribute to destroy the device
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).
@@ -230,6 +237,8 @@ status - Can be 'online' or '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.
3. System devices