ipmi: Turn off all activity on an idle ipmi interface

The IPMI driver would wake up periodically looking for events and
watchdog pretimeouts.  If there is nothing waiting for these events,
it's really kind of pointless to be checking for them.  So modify the
driver so the message handler can pass down if it needs the lower layer
to be waiting for these.  Modify the system interface lower layer to
turn off all timer and thread activity if the upper layer doesn't need
anything and it is not currently handling messages.  And modify the
message handler to not restart the timer if its timer is not needed.

The timers and kthread will still be enabled if:
 - the SI interface is handling a message.
 - a user has enabled watching for events.
 - the IPMI watchdog timer is in use (since it uses pretimeouts).
 - the message handler is waiting on a remote response.
 - a user has registered to receive commands.

This mostly affects interfaces without interrupts.  Interfaces with
interrupts already don't use CPU in the system interface when the
interface is idle.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/ipmi_smi.h b/include/linux/ipmi_smi.h
index 8ea3fe0b9759..2a7ff302d990 100644
--- a/include/linux/ipmi_smi.h
+++ b/include/linux/ipmi_smi.h
@@ -109,6 +109,13 @@ struct ipmi_smi_handlers {
            events from the BMC we are attached to. */
         void (*request_events)(void *send_info);
 
+        /* Called by the upper layer when some user requires that the
+           interface watch for events, received messages, watchdog
+           pretimeouts, or not.  Used by the SMI to know if it should
+           watch for these.  This may be NULL if the SMI does not
+           implement it. */
+        void (*set_need_watch)(void *send_info, int enable);
+
         /* Called when the interface should go into "run to
            completion" mode.  If this call sets the value to true, the
            interface should make sure that all messages are flushed