Map bus memory into cpu space
void __iomem * ioremap_nocache(resource_size_t offset, unsigned long size);
offset
bus address of the memory
size
size of the resource to map
ioremap performs a platform specific sequence of operations to make bus memory CPU accessible via the readb/readw/readl/writeb/ writew/writel functions and the other mmio helpers. The returned address is not guaranteed to be usable directly as a virtual address.
If the area you are trying to map is a PCI BAR you should have a look at pci_iomap.