int pci_legacy_read()

in pci/pci-common.c [218:255]

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

int pci_legacy_read(struct pci_bus *bus, loff_t port, u32 *val, size_t size)
{
	unsigned long offset;
	struct pci_controller *hose = pci_bus_to_host(bus);
	struct resource *rp = &hose->io_resource;
	void __iomem *addr;

	/* Check if port can be supported by that bus. We only check
	 * the ranges of the PHB though, not the bus itself as the rules
	 * for forwarding legacy cycles down bridges are not our problem
	 * here. So if the host bridge supports it, we do it.
	 */
	offset = (unsigned long)hose->io_base_virt - _IO_BASE;
	offset += port;

	if (!(rp->flags & IORESOURCE_IO))
		return -ENXIO;
	if (offset < rp->start || (offset + size) > rp->end)
		return -ENXIO;
	addr = hose->io_base_virt + port;

	switch (size) {
	case 1:
		*((u8 *)val) = in_8(addr);
		return 1;
	case 2:
		if (port & 1)
			return -EINVAL;
		*((u16 *)val) = in_le16(addr);
		return 2;
	case 4:
		if (port & 3)
			return -EINVAL;
		*((u32 *)val) = in_le32(addr);
		return 4;
	}
	return -EINVAL;
}