pgprot_t pci_phys_mem_access_prot()

in pci/pci-common.c [173:215]

• 36 lines of code
• 9 McCabe index (conditional complexity)

pgprot_t pci_phys_mem_access_prot(struct file *file,
				  unsigned long pfn,
				  unsigned long size,
				  pgprot_t prot)
{
	struct pci_dev *pdev = NULL;
	struct resource *found = NULL;
	resource_size_t offset = ((resource_size_t)pfn) << PAGE_SHIFT;
	int i;

	if (page_is_ram(pfn))
		return prot;

	prot = pgprot_noncached(prot);
	for_each_pci_dev(pdev) {
		for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
			struct resource *rp = &pdev->resource[i];
			int flags = rp->flags;

			/* Active and same type? */
			if ((flags & IORESOURCE_MEM) == 0)
				continue;
			/* In the range of this resource? */
			if (offset < (rp->start & PAGE_MASK) ||
			    offset > rp->end)
				continue;
			found = rp;
			break;
		}
		if (found)
			break;
	}
	if (found) {
		if (found->flags & IORESOURCE_PREFETCH)
			prot = pgprot_noncached_wc(prot);
		pci_dev_put(pdev);
	}

	pr_debug("PCI: Non-PCI map for %llx, prot: %lx\n",
		 (unsigned long long)offset, pgprot_val(prot));

	return prot;
}