[PATCH v7 3/3] arm64: Add architecture support for PCI

[Liviu Dudau]

Use the generic host bridge functions to provide support for
PCI Express on arm64. There is no support for ISA memory.

Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
Tested-by: Tanmay Inamdar <tinamdar@xxxxxxx>
---
 arch/arm64/Kconfig            |  19 +++-
 arch/arm64/include/asm/Kbuild |   1 +
 arch/arm64/include/asm/io.h   |   3 +-
 arch/arm64/include/asm/pci.h  |  51 ++++++++++
 arch/arm64/kernel/Makefile    |   1 +
 arch/arm64/kernel/pci.c       | 173 ++++++++++++++++++++++++++++++++
 6 files changed, 246 insertions(+), 2 deletions(-)
 create mode 100644 arch/arm64/include/asm/pci.h
 create mode 100644 arch/arm64/kernel/pci.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 27bbcfc..d1c8568 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -62,7 +62,7 @@ config MMU
 	def_bool y
 
 config NO_IOPORT
-	def_bool y
+	def_bool y if !PCI
 
 config STACKTRACE_SUPPORT
 	def_bool y
@@ -134,6 +134,23 @@ menu "Bus support"
 config ARM_AMBA
 	bool
 
+config PCI
+	bool "PCI support"
+	help
+	  This feature enables support for PCIe bus system. If you say Y
+	  here, the kernel will include drivers and infrastructure code
+	  to support PCIe bus devices.
+
+config PCI_DOMAINS
+	def_bool PCI
+
+config PCI_SYSCALL
+	def_bool PCI
+
+source "drivers/pci/Kconfig"
+source "drivers/pci/pcie/Kconfig"
+source "drivers/pci/hotplug/Kconfig"
+
 endmenu
 
 menu "Kernel Features"
diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index 71c53ec..46924bc 100644
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -26,6 +26,7 @@ generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += mutex.h
 generic-y += pci.h
+generic-y += pci-bridge.h
 generic-y += poll.h
 generic-y += posix_types.h
 generic-y += resource.h
diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 7846a6b..67463a5 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -120,7 +120,8 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
 /*
  *  I/O port access primitives.
  */
-#define IO_SPACE_LIMIT		0xffff
+#define arch_has_dev_port()	(1)
+#define IO_SPACE_LIMIT		0x1ffffff
 #define PCI_IOBASE		((void __iomem *)(MODULES_VADDR - SZ_32M))
 
 static inline u8 inb(unsigned long addr)
diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
new file mode 100644
index 0000000..d93576f
--- /dev/null
+++ b/arch/arm64/include/asm/pci.h
@@ -0,0 +1,51 @@
+#ifndef __ASM_PCI_H
+#define __ASM_PCI_H
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/dma-mapping.h>
+
+#include <asm/io.h>
+#include <asm-generic/pci-bridge.h>
+#include <asm-generic/pci-dma-compat.h>
+
+#define PCIBIOS_MIN_IO		0x1000
+#define PCIBIOS_MIN_MEM		0
+
+struct pci_host_bridge *find_pci_host_bridge(struct pci_bus *bus);
+
+/*
+ * Set to 1 if the kernel should re-assign all PCI bus numbers
+ */
+#define pcibios_assign_all_busses() \
+	(pci_has_flag(PCI_REASSIGN_ALL_BUS))
+
+/*
+ * PCI address space differs from physical memory address space
+ */
+#define PCI_DMA_BUS_IS_PHYS	(0)
+
+extern int isa_dma_bridge_buggy;
+
+#ifdef CONFIG_PCI
+static inline int pci_domain_nr(struct pci_bus *bus)
+{
+	struct pci_host_bridge *bridge = find_pci_host_bridge(bus);
+
+	if (bridge)
+		return bridge->domain_nr;
+
+	return 0;
+}
+
+static inline int pci_proc_domain(struct pci_bus *bus)
+{
+	return 1;
+}
+#endif
+
+extern unsigned long pci_ioremap_io(const struct resource *res, phys_addr_t phys_addr);
+
+#endif  /* __KERNEL__ */
+#endif  /* __ASM_PCI_H */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 2d4554b..64fc479 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -20,6 +20,7 @@ arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o
 arm64-obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND)	+= sleep.o suspend.o
 arm64-obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
+arm64-obj-$(CONFIG_PCI)			+= pci.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)
diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
new file mode 100644
index 0000000..9f29c9a
--- /dev/null
+++ b/arch/arm64/kernel/pci.c
@@ -0,0 +1,173 @@
+/*
+ * Code borrowed from powerpc/kernel/pci-common.c
+ *
+ * Copyright (C) 2003 Anton Blanchard <anton@xxxxxxxxxx>, IBM
+ * Copyright (C) 2014 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/of_pci.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+
+#include <asm/pci-bridge.h>
+
+struct ioresource {
+	struct list_head list;
+	phys_addr_t start;
+	resource_size_t size;
+};
+
+static LIST_HEAD(io_list);
+
+int pci_register_io_range(phys_addr_t address, resource_size_t size)
+{
+	struct ioresource *res;
+	resource_size_t allocated_size = 0;
+
+	/* find if the range has not been already allocated */
+	list_for_each_entry(res, &io_list, list) {
+		if (address >= res->start &&
+			address + size <= res->start + size)
+			return 0;
+		allocated_size += res->size;
+	}
+
+	/* range not already registered, check for space */
+	if (allocated_size + size > IO_SPACE_LIMIT)
+		return -E2BIG;
+
+	/* add the range in the list */
+	res = kzalloc(sizeof(*res), GFP_KERNEL);
+	if (!res)
+		return -ENOMEM;
+	res->start = address;
+	res->size = size;
+
+	list_add_tail(&res->list, &io_list);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_register_io_range);
+
+unsigned long pci_address_to_pio(phys_addr_t address)
+{
+	struct ioresource *res;
+
+	list_for_each_entry(res, &io_list, list) {
+		if (address >= res->start &&
+			address < res->start + res->size) {
+			return res->start - address;
+		}
+	}
+
+	return (unsigned long)-1;
+}
+EXPORT_SYMBOL_GPL(pci_address_to_pio);
+
+/*
+ * Called after each bus is probed, but before its children are examined
+ */
+void pcibios_fixup_bus(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+	struct resource *res;
+	int i;
+
+	if (!pci_is_root_bus(bus)) {
+		pci_read_bridge_bases(bus);
+
+		pci_bus_for_each_resource(bus, res, i) {
+			if (!res || !res->flags || res->parent)
+				continue;
+
+			/*
+			 * If we are going to reassign everything, we can
+			 * shrink the P2P resource to have zero size to
+			 * save space
+			 */
+			if (pci_has_flag(PCI_REASSIGN_ALL_RSRC)) {
+				res->flags |= IORESOURCE_UNSET;
+				res->start = 0;
+				res->end = -1;
+				continue;
+			}
+		}
+	}
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		/* Ignore fully discovered devices */
+		if (dev->is_added)
+			continue;
+
+		set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
+
+		/* Read default IRQs and fixup if necessary */
+		dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
+	}
+}
+EXPORT_SYMBOL(pcibios_fixup_bus);
+
+/*
+ * We don't have to worry about legacy ISA devices, so nothing to do here
+ */
+resource_size_t pcibios_align_resource(void *data, const struct resource *res,
+				resource_size_t size, resource_size_t align)
+{
+	return res->start;
+}
+
+int pcibios_enable_device(struct pci_dev *dev, int mask)
+{
+	return pci_enable_resources(dev, mask);
+}
+
+#define IO_SPACE_PAGES	((IO_SPACE_LIMIT + 1) / PAGE_SIZE)
+static DECLARE_BITMAP(pci_iospace, IO_SPACE_PAGES);
+
+unsigned long pci_ioremap_io(const struct resource *res, phys_addr_t phys_addr)
+{
+	unsigned long start, len, virt_start;
+	int err;
+
+	if (res->end > IO_SPACE_LIMIT)
+		return -EINVAL;
+
+	/*
+	 * try finding free space for the whole size first,
+	 * fall back to 64K if not available
+	 */
+	len = resource_size(res);
+	start = bitmap_find_next_zero_area(pci_iospace, IO_SPACE_PAGES,
+				res->start / PAGE_SIZE, len / PAGE_SIZE, 0);
+	if (start == IO_SPACE_PAGES && len > SZ_64K) {
+		len = SZ_64K;
+		start = 0;
+		start = bitmap_find_next_zero_area(pci_iospace, IO_SPACE_PAGES,
+					start, len / PAGE_SIZE, 0);
+	}
+
+	/* no 64K area found */
+	if (start == IO_SPACE_PAGES)
+		return -ENOMEM;
+
+	/* ioremap physical aperture to virtual aperture */
+	virt_start = start * PAGE_SIZE + (unsigned long)PCI_IOBASE;
+	err = ioremap_page_range(virt_start, virt_start + len,
+				phys_addr, __pgprot(PROT_DEVICE_nGnRE));
+	if (err)
+		return err;
+
+	bitmap_set(pci_iospace, start, len / PAGE_SIZE);
+
+	/* return io_offset */
+	return start * PAGE_SIZE - res->start;
+}
-- 
1.9.0

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