openrisc: Add pci bus support

This patch adds required definitions to allow for PCI buses on OpenRISC.
This is being tested on the OpenRISC QEMU virt platform which is in
development.

OpenRISC does not have IO ports so we keep the definition of
IO_SPACE_LIMIT and PIO_RESERVED to be 0.

Note, since commit 66bcd06099 ("parport_pc: Also enable driver for PCI
systems") all platforms that support PCI also need to support parallel
port.  We add a generic header to support compiling parallel port
drivers, though they generally will not work as they require IO ports.

Signed-off-by: Stafford Horne <shorne@gmail.com>

arch/openrisc/Kconfig

@@ -20,8 +20,9 @@ config OPENRISC
 	select GENERIC_IRQ_CHIP
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
-	select GENERIC_IOMAP
+	select GENERIC_PCI_IOMAP
 	select GENERIC_CPU_DEVICES
+	select HAVE_PCI
 	select HAVE_UID16
 	select GENERIC_ATOMIC64
 	select GENERIC_CLOCKEVENTS_BROADCAST
@@ -32,6 +33,8 @@ config OPENRISC
 	select CPU_NO_EFFICIENT_FFS if !OPENRISC_HAVE_INST_FF1
 	select ARCH_USE_QUEUED_RWLOCKS
 	select OMPIC if SMP
+	select PCI_DOMAINS_GENERIC if PCI
+	select PCI_MSI if PCI
 	select ARCH_WANT_FRAME_POINTERS
 	select GENERIC_IRQ_MULTI_HANDLER
 	select MMU_GATHER_NO_RANGE if MMU

arch/openrisc/include/asm/Kbuild

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 generic-y += extable.h
 generic-y += kvm_para.h
+generic-y += parport.h
 generic-y += spinlock_types.h
 generic-y += spinlock.h
 generic-y += qrwlock_types.h

arch/openrisc/include/asm/io.h

@@ -17,7 +17,7 @@
 #include <linux/types.h>
 
 /*
- * PCI: can we really do 0 here if we have no port IO?
+ * PCI: We do not use IO ports in OpenRISC
  */
 #define IO_SPACE_LIMIT		0