s390: convert interrupt handling to use generic hardirq

With the introduction of PCI it became apparent that s390 should
convert to generic hardirqs as too many drivers do not have the
correct dependency for GENERIC_HARDIRQS. On the architecture
level s390 does not have irq lines. It has external interrupts,
I/O interrupts and adapter interrupts. This patch hard-codes all
external interrupts as irq #1, all I/O interrupts as irq #2 and
all adapter interrupts as irq #3. The additional information from
the lowcore associated with the interrupt is stored in the
pt_regs of the interrupt frame, where the interrupt handler can
pick it up. For PCI/MSI interrupts the adapter interrupt handler
scans the relevant bit fields and calls generic_handle_irq with
the virtual irq number for the MSI interrupt.

Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 8a4cae78f03c..8b7892bf6d8b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -116,6 +116,7 @@ config S390
         select HAVE_FUNCTION_GRAPH_TRACER
         select HAVE_FUNCTION_TRACER
         select HAVE_FUNCTION_TRACE_MCOUNT_TEST
+        select HAVE_GENERIC_HARDIRQS
         select HAVE_KERNEL_BZIP2
         select HAVE_KERNEL_GZIP
         select HAVE_KERNEL_LZ4
@@ -445,6 +446,16 @@ config PCI_NR_FUNCTIONS
           This allows you to specify the maximum number of PCI functions which
           this kernel will support.
 
+config PCI_NR_MSI
+        int "Maximum number of MSI interrupts (64-32768)"
+        range 64 32768
+        default "256"
+        help
+          This defines the number of virtual interrupts the kernel will
+          provide for MSI interrupts. If you configure your system to have
+          too few drivers will fail to allocate MSI interrupts for all
+          PCI devices.
+
 source "drivers/pci/Kconfig"
 source "drivers/pci/pcie/Kconfig"
 source "drivers/pci/hotplug/Kconfig"