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Commit f7195824 authored by David Woodhouse's avatar David Woodhouse Committed by Bjorn Helgaas
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PCI: Add pci_mmap_resource_range() and use it for ARM64 



Starting to leave behind the legacy of the pci_mmap_page_range() interface
which takes "user-visible" BAR addresses.  This takes just the resource and
offset.

For now, both APIs coexist and depending on the platform, one is
implemented as a wrapper around the other.

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent f66e2258

Documentation/filesystems/sysfs-pci.txt

+7 −3
Original line number Diff line number Diff line
@@ -113,9 +113,13 @@ Supporting PCI access on new platforms 
--------------------------------------



In order to support PCI resource mapping as described above, Linux platform

code must define HAVE_PCI_MMAP and provide a pci_mmap_page_range function.

Platforms are free to only support subsets of the mmap functionality, but

useful return codes should be provided.

code should ideally define ARCH_GENERIC_PCI_MMAP_RESOURCE and use the generic

implementation of that functionality. To support the historical interface of

mmap() through files in /proc/bus/pci, platforms may also set HAVE_PCI_MMAP.



Alternatively, platforms which set HAVE_PCI_MMAP may provide their own

implementation of pci_mmap_page_range() instead of defining

ARCH_GENERIC_PCI_MMAP_RESOURCE.



Platforms which support write-combining maps of PCI resources must define

arch_can_pci_mmap_wc() which shall evaluate to non-zero at runtime when

arch/arm64/include/asm/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
 */

#define PCI_DMA_BUS_IS_PHYS	(0)



#define ARCH_GENERIC_PCI_MMAP_RESOURCE	1



extern int isa_dma_bridge_buggy;



#ifdef CONFIG_PCI

drivers/pci/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 


obj-y		+= access.o bus.o probe.o host-bridge.o remove.o pci.o \

			pci-driver.o search.o pci-sysfs.o rom.o setup-res.o \

			irq.o vpd.o setup-bus.o vc.o

			irq.o vpd.o setup-bus.o vc.o mmap.o

obj-$(CONFIG_PROC_FS) += proc.o

obj-$(CONFIG_SYSFS) += slot.o

drivers/pci/mmap.c

0 → 100644
+95 −0
Original line number Diff line number Diff line 
/*

 * mmap.c — generic PCI resource mmap helper

 *

 * Copyright © 2017 Amazon.com, Inc. or its affiliates.

 *

 * Author: David Woodhouse <dwmw2@infradead.org>

 *

 * 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/kernel.h>

#include <linux/mm.h>

#include <linux/pci.h>



#ifdef ARCH_GENERIC_PCI_MMAP_RESOURCE



/*

 * Modern setup: generic pci_mmap_resource_range(), and implement the legacy

 * pci_mmap_page_range() (if needed) as a wrapper round it.

 */



#ifdef HAVE_PCI_MMAP

int pci_mmap_page_range(struct pci_dev *pdev, int bar,

			struct vm_area_struct *vma,

			enum pci_mmap_state mmap_state, int write_combine)

{

	resource_size_t start, end;



	pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);



	/* Adjust vm_pgoff to be the offset within the resource */

	vma->vm_pgoff -= start >> PAGE_SHIFT;

	return pci_mmap_resource_range(pdev, bar, vma, mmap_state,

				       write_combine);

}

#endif



static const struct vm_operations_struct pci_phys_vm_ops = {

#ifdef CONFIG_HAVE_IOREMAP_PROT

	.access = generic_access_phys,

#endif

};



int pci_mmap_resource_range(struct pci_dev *pdev, int bar,

			    struct vm_area_struct *vma,

			    enum pci_mmap_state mmap_state, int write_combine)

{

	unsigned long size;



	if (mmap_state == pci_mmap_io)

		return -EINVAL;



	size = ((pci_resource_len(pdev, bar) - 1) >> PAGE_SHIFT) + 1;

	if (vma->vm_pgoff + vma_pages(vma) > size)

		return -EINVAL;



	if (write_combine)

		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);

	else

		vma->vm_page_prot = pgprot_device(vma->vm_page_prot);



	vma->vm_pgoff += (pci_resource_start(pdev, bar) >> PAGE_SHIFT);

	vma->vm_ops = &pci_phys_vm_ops;



	return io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,

				  vma->vm_end - vma->vm_start,

				  vma->vm_page_prot);

}



#elif defined(HAVE_PCI_MMAP) /* && !ARCH_GENERIC_PCI_MMAP_RESOURCE */



/*

 * Legacy setup: Impement pci_mmap_resource_range() as a wrapper around

 * the architecture's pci_mmap_page_range(), converting to "user visible"

 * addresses as necessary.

 */



int pci_mmap_resource_range(struct pci_dev *pdev, int bar,

			    struct vm_area_struct *vma,

			    enum pci_mmap_state mmap_state, int write_combine)

{

	resource_size_t start, end;



	/*

	 * pci_mmap_page_range() expects the same kind of entry as coming

	 * from /proc/bus/pci/ which is a "user visible" value. If this is

	 * different from the resource itself, arch will do necessary fixup.

	 */

	pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);

	vma->vm_pgoff += start >> PAGE_SHIFT;

	return pci_mmap_page_range(pdev, bar, vma, mmap_state, write_combine);

}

#endif

drivers/pci/pci-sysfs.c

+3 −10
Original line number Diff line number Diff line
@@ -980,7 +980,7 @@ void pci_remove_legacy_files(struct pci_bus *b) 
}

#endif /* HAVE_PCI_LEGACY */



#ifdef HAVE_PCI_MMAP

#if defined(HAVE_PCI_MMAP) || defined(ARCH_GENERIC_PCI_MMAP_RESOURCE)



int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vma,

		  enum pci_mmap_api mmap_api)
@@ -1019,7 +1019,6 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, 
	struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));

	int bar = (unsigned long)attr->private;

	enum pci_mmap_state mmap_type;

	resource_size_t start, end;

	struct resource *res = &pdev->resource[bar];



	if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start))
@@ -1033,15 +1032,9 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, 
			(u64)pci_resource_len(pdev, bar));

		return -EINVAL;

	}



	/* pci_mmap_page_range() expects the same kind of entry as coming

	 * from /proc/bus/pci/ which is a "user visible" value. If this is

	 * different from the resource itself, arch will do necessary fixup.

	 */

	pci_resource_to_user(pdev, bar, res, &start, &end);

	vma->vm_pgoff += start >> PAGE_SHIFT;

	mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;

	return pci_mmap_page_range(pdev, bar, vma, mmap_type, write_combine);



	return pci_mmap_resource_range(pdev, bar, vma, mmap_type, write_combine);

}



static int pci_mmap_resource_uc(struct file *filp, struct kobject *kobj,