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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: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
hifive-unleashed-5.1
David Woodhouse 2017-04-12 13:25:59 +01:00 committed by Bjorn Helgaas
parent f66e225828
commit f719582435
7 changed files with 125 additions and 20 deletions
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10
Documentation/filesystems/sysfs-pci.txt
View File

@ -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

2
arch/arm64/include/asm/pci.h
View File

@ -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

2
drivers/pci/Makefile
View File

@ -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

95
drivers/pci/mmap.c 100644
View File

@ -0,0 +1,95 @@
/*
* 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

13
drivers/pci/pci-sysfs.c
View File

@ -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,

4
drivers/pci/pci.h
View File

@ -21,14 +21,14 @@ void pci_create_firmware_label_files(struct pci_dev *pdev);
void pci_remove_firmware_label_files(struct pci_dev *pdev);
#endif
void pci_cleanup_rom(struct pci_dev *dev);
#ifdef HAVE_PCI_MMAP
enum pci_mmap_api {
PCI_MMAP_SYSFS, /* mmap on /sys/bus/pci/devices/<BDF>/resource<N> */
PCI_MMAP_PROCFS /* mmap on /proc/bus/pci/<BDF> */
};
int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vmai,
enum pci_mmap_api mmap_api);
#endif
int pci_probe_reset_function(struct pci_dev *dev);
/**

19
include/linux/pci.h
View File

@ -1626,10 +1626,21 @@ static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
#include <asm/pci.h>
/* Map a range of PCI memory or I/O space for a device into user space.
* Architectures provide this function if they set HAVE_PCI_MMAP, and
* it accepts the 'write_combine' argument when arch_can_pci_mmap_wc()
* evaluates to nonzero. */
/* These two functions provide almost identical functionality. Depennding
* on the architecture, one will be implemented as a wrapper around the
* other (in drivers/pci/mmap.c).
*
* pci_mmap_resource_range() maps a specific BAR, and vm->vm_pgoff
* is expected to be an offset within that region.
*
* pci_mmap_page_range() is the legacy architecture-specific interface,
* which accepts a "user visible" resource address converted by
* pci_resource_to_user(), as used in the legacy mmap() interface in
* /proc/bus/pci/.
*/
int pci_mmap_resource_range(struct pci_dev *dev, int bar,
struct vm_area_struct *vma,
enum pci_mmap_state mmap_state, int write_combine);
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);