s390/pci: PCI adapter interrupts for MSI/MSI-X

Support PCI adapter interrupts using the Single-IRQ-mode. Single-IRQ-mode
disables an adapter IRQ automatically after delivering it until the SIC
instruction enables it again. This is used to reduce the number of IRQs
for streaming workloads.

Up to 64 MSI handlers can be registered per PCI function.
A hash table is used to map interrupt numbers to MSI descriptors.
The interrupt vector is scanned using the flogr instruction.
Only MSI/MSI-X interrupts are supported, no legacy INTs.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 216b0ba..e21ed83 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -10,9 +10,6 @@
  */
 
 #include <linux/smp.h>
-
-#ifndef CONFIG_S390
-
 #include <linux/linkage.h>
 #include <linux/cache.h>
 #include <linux/spinlock.h>
@@ -737,8 +734,11 @@
 static inline void irq_gc_unlock(struct irq_chip_generic *gc) { }
 #endif
 
-#endif /* CONFIG_GENERIC_HARDIRQS */
+#else /* !CONFIG_GENERIC_HARDIRQS */
 
-#endif /* !CONFIG_S390 */
+extern struct msi_desc *irq_get_msi_desc(unsigned int irq);
+extern int irq_set_msi_desc(unsigned int irq, struct msi_desc *entry);
+
+#endif /* CONFIG_GENERIC_HARDIRQS */
 
 #endif /* _LINUX_IRQ_H */