csky: Add PCI support

Add the pci related code for csky arch to support basic pci virtual
function, such as qemu virt-pci-9pfs.

Signed-off-by: MaJun <majun258@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

arch/csky/Kconfig

@@ -58,6 +58,11 @@ config CSKY
 	select TIMER_OF
 	select USB_ARCH_HAS_EHCI
 	select USB_ARCH_HAS_OHCI
+	select GENERIC_PCI_IOMAP
+	select HAVE_PCI
+	select PCI_DOMAINS_GENERIC if PCI
+	select PCI_SYSCALL if PCI
+	select PCI_MSI if PCI
 
 config CPU_HAS_CACHEV2
 	bool

arch/csky/include/asm/Kbuild

@@ -28,7 +28,6 @@ generic-y += local64.h
 generic-y += mm-arch-hooks.h
 generic-y += mmiowb.h
 generic-y += module.h
-generic-y += pci.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += qrwlock.h

arch/csky/include/asm/pci.h

@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_CSKY_PCI_H
+#define __ASM_CSKY_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
+
+/* C-SKY shim does not initialize PCI bus */
+#define pcibios_assign_all_busses() 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 IRQ on csky */
+	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_CSKY_PCI_H */