s390/cio: clarify cssid usage

Currently the cssid in various structures is used as the id of
the respective channel subsystem. Sometimes however we call the
index in the channel_subsystems array cssid. In some places the
id is even used as the index.

Provide a new define MAX_CSS_IDX and use it where appropriate.
In addition to that provide a dummy function to find a channel
subsystem by its id and a macro to iterate over the channel
subsystems.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h
index 2c9107e20251..cd19c08b93b2 100644
--- a/drivers/s390/cio/css.h
+++ b/drivers/s390/cio/css.h
@@ -130,6 +130,16 @@ struct channel_subsystem {
 
 extern struct channel_subsystem *channel_subsystems[];
 
+/* Dummy helper which needs to change once we support more than one css. */
+static inline struct channel_subsystem *css_by_id(u8 cssid)
+{
+	return channel_subsystems[0];
+}
+
+/* Dummy iterator which needs to change once we support more than one css. */
+#define for_each_css(css)						\
+	for ((css) = channel_subsystems[0]; (css); (css) = NULL)
+
 /* Helper functions to build lists for the slow path. */
 void css_schedule_eval(struct subchannel_id schid);
 void css_schedule_eval_all(void);