openrisc: Add pci bus support

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

OpenRISC does not have IO ports so this defines PCI IO to be allowed in
any range.  Keeping PIO_RESERVED defined as 0 allows OpenRISC to use
MMIO for all IO.

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

arch/openrisc/Kconfig

@@ -21,7 +21,9 @@ config OPENRISC
 	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 +34,8 @@ 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
@@ -46,9 +50,6 @@ config MMU
 config GENERIC_HWEIGHT
 	def_bool y
 
-config NO_IOPORT_MAP
-	def_bool y
-
 # For now, use generic checksum functions
 #These can be reimplemented in assembly later if so inclined
 config GENERIC_CSUM

arch/openrisc/include/asm/io.h

@@ -17,9 +17,9 @@
 #include <linux/types.h>
 
 /*
- * PCI: can we really do 0 here if we have no port IO?
+ * PCI: All address space can be used for IO
  */
-#define IO_SPACE_LIMIT		0
+#define IO_SPACE_LIMIT ~(0UL)
 
 /* OpenRISC has no port IO */
 #define HAVE_ARCH_PIO_SIZE	1

arch/openrisc/include/asm/pci.h

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_OPENRISC_PCI_H
+#define __ASM_OPENRISC_PCI_H
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/dma-mapping.h>
+
+#include <asm/io.h>
+
+#define PCIBIOS_MIN_IO		0
+#define PCIBIOS_MIN_MEM		0
+
+/* OpenRISC bootloaders do not initialize PCI bus */
+#define pcibios_assign_all_busses() 1
+
+#define ARCH_GENERIC_PCI_MMAP_RESOURCE 1
+
+extern int isa_dma_bridge_buggy;
+
+#ifdef CONFIG_PCI
+static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
+{
+	/* no legacy IRQs on or1k */
+	return -ENODEV;
+}
+
+static inline int pci_proc_domain(struct pci_bus *bus)
+{
+	/* always show the domain in /proc */
+	return 1;
+}
+#endif /* CONFIG_PCI */
+
+#endif /* __ASM_OPENRISC_PCI_H */