// SPDX-License-Identifier: GPL-2.0

  /*

   * Generic PCI resource mmap helper

   *
   * Copyright © 2017 Amazon.com, Inc. or its affiliates.
   *
   * Author: David Woodhouse <dwmw2@infradead.org>

   */
  
  #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;

  	int ret;

  
  	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);

  	if (mmap_state == pci_mmap_io) {
  		ret = pci_iobar_pfn(pdev, bar, vma);
  		if (ret)
  			return ret;
  	} else
  		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: Implement 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