drivers/pci/mmap.c

   1 /*
   2  * mmap.c — generic PCI resource mmap helper
   3  *
   4  * Copyright © 2017 Amazon.com, Inc. or its affiliates.
   5  *
   6  * Author: David Woodhouse <dwmw2@infradead.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/mm.h>
  15 #include <linux/pci.h>
  16
  17 #ifdef ARCH_GENERIC_PCI_MMAP_RESOURCE
  18
  19 /*
  20  * Modern setup: generic pci_mmap_resource_range(), and implement the legacy
  21  * pci_mmap_page_range() (if needed) as a wrapper round it.
  22  */
  23
  24 #ifdef HAVE_PCI_MMAP
  25 int pci_mmap_page_range(struct pci_dev *pdev, int bar,
  26                         struct vm_area_struct *vma,
  27                         enum pci_mmap_state mmap_state, int write_combine)
  28 {
  29         resource_size_t start, end;
  30
  31         pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);
  32
  33         /* Adjust vm_pgoff to be the offset within the resource */
  34         vma->vm_pgoff -= start >> PAGE_SHIFT;
  35         return pci_mmap_resource_range(pdev, bar, vma, mmap_state,
  36                                        write_combine);
  37 }
  38 #endif
  39
  40 static const struct vm_operations_struct pci_phys_vm_ops = {
  41 #ifdef CONFIG_HAVE_IOREMAP_PROT
  42         .access = generic_access_phys,
  43 #endif
  44 };
  45
  46 int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
  47                             struct vm_area_struct *vma,
  48                             enum pci_mmap_state mmap_state, int write_combine)
  49 {
  50         unsigned long size;
  51         int ret;
  52
  53         size = ((pci_resource_len(pdev, bar) - 1) >> PAGE_SHIFT) + 1;
  54         if (vma->vm_pgoff + vma_pages(vma) > size)
  55                 return -EINVAL;
  56
  57         if (write_combine)
  58                 vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
  59         else
  60                 vma->vm_page_prot = pgprot_device(vma->vm_page_prot);
  61
  62         if (mmap_state == pci_mmap_io) {
  63                 ret = pci_iobar_pfn(pdev, bar, vma);
  64                 if (ret)
  65                         return ret;
  66         } else
  67                 vma->vm_pgoff += (pci_resource_start(pdev, bar) >> PAGE_SHIFT);
  68
  69         vma->vm_ops = &pci_phys_vm_ops;
  70
  71         return io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
  72                                   vma->vm_end - vma->vm_start,
  73                                   vma->vm_page_prot);
  74 }
  75
  76 #elif defined(HAVE_PCI_MMAP) /* && !ARCH_GENERIC_PCI_MMAP_RESOURCE */
  77
  78 /*
  79  * Legacy setup: Impement pci_mmap_resource_range() as a wrapper around
  80  * the architecture's pci_mmap_page_range(), converting to "user visible"
  81  * addresses as necessary.
  82  */
  83
  84 int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
  85                             struct vm_area_struct *vma,
  86                             enum pci_mmap_state mmap_state, int write_combine)
  87 {
  88         resource_size_t start, end;
  89
  90         /*
  91          * pci_mmap_page_range() expects the same kind of entry as coming
  92          * from /proc/bus/pci/ which is a "user visible" value. If this is
  93          * different from the resource itself, arch will do necessary fixup.
  94          */
  95         pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);
  96         vma->vm_pgoff += start >> PAGE_SHIFT;
  97         return pci_mmap_page_range(pdev, bar, vma, mmap_state, write_combine);
  98 }
  99 #endif