powerpc/pseries: Add support for IO event interrupts

This patch adds support for handling IO Event interrupts which come
through at the /event-sources/ibm,io-events device tree node.

The interrupts come through ibm,io-events device tree node are generated
by the firmware to report IO events. The firmware uses the same interrupt
to report multiple types of events for multiple devices. Each device may
have its own event handler. This patch implements a plateform interrupt
handler that is triggered by the IO event interrupts come through
ibm,io-events device tree node, pull in the IO events from RTAS and call
device event handlers registered in the notifier list.

Device event handlers are expected to use atomic_notifier_chain_register()
and atomic_notifier_chain_unregister() to register/unregister their
event handler in pseries_ioei_notifier_list list with IO event interrupt.
Device event handlers are responsible to identify if the event belongs
to the device event handler. The device event handle should return NOTIFY_OK
after the event is handled if the event belongs to the device event handler,
or NOTIFY_DONE otherwise.

Signed-off-by: Tseng-Hui (Frank) Lin <thlin@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index b0449229836e..71af4c5d6c05 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -50,6 +50,24 @@ config SCANLOG
         tristate "Scanlog dump interface"
         depends on RTAS_PROC && PPC_PSERIES
 
+config IO_EVENT_IRQ
+        bool "IO Event Interrupt support"
+        depends on PPC_PSERIES
+        default y
+        help
+          Select this option, if you want to enable support for IO Event
+          interrupts. IO event interrupt is a mechanism provided by RTAS
+          to return information about hardware error and non-error events
+          which may need OS attention. RTAS returns events for multiple
+          event types and scopes. Device drivers can register their handlers
+          to receive events.
+
+          This option will only enable the IO event platform code. You
+          will still need to enable or compile the actual drivers
+          that use this infrastruture to handle IO event interrupts.
+
+          Say Y if you are unsure.
+
 config LPARCFG
         bool "LPAR Configuration Data"
         depends on PPC_PSERIES || PPC_ISERIES