lib: add GENERIC_PCI_IOMAP

Many architectures want a generic pci_iomap but
not the rest of iomap.c. Split that to a separate .c
file and add a new config symbol. select automatically
by GENERIC_IOMAP.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/lib/iomap.c b/lib/iomap.c
index 5dbcb4b..ada922a 100644
--- a/lib/iomap.c
+++ b/lib/iomap.c
@@ -242,45 +242,11 @@
 #endif /* CONFIG_HAS_IOPORT */
 
 #ifdef CONFIG_PCI
-/**
- * pci_iomap - create a virtual mapping cookie for a PCI BAR
- * @dev: PCI device that owns the BAR
- * @bar: BAR number
- * @maxlen: length of the memory to map
- *
- * Using this function you will get a __iomem address to your device BAR.
- * You can access it using ioread*() and iowrite*(). These functions hide
- * the details if this is a MMIO or PIO address space and will just do what
- * you expect from them in the correct way.
- *
- * @maxlen specifies the maximum length to map. If you want to get access to
- * the complete BAR without checking for its length first, pass %0 here.
- * */
-void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
-{
-	resource_size_t start = pci_resource_start(dev, bar);
-	resource_size_t len = pci_resource_len(dev, bar);
-	unsigned long flags = pci_resource_flags(dev, bar);
-
-	if (!len || !start)
-		return NULL;
-	if (maxlen && len > maxlen)
-		len = maxlen;
-	if (flags & IORESOURCE_IO)
-		return ioport_map(start, len);
-	if (flags & IORESOURCE_MEM) {
-		if (flags & IORESOURCE_CACHEABLE)
-			return ioremap(start, len);
-		return ioremap_nocache(start, len);
-	}
-	/* What? */
-	return NULL;
-}
-
+/* Hide the details if this is a MMIO or PIO address space and just do what
+ * you expect in the correct way. */
 void pci_iounmap(struct pci_dev *dev, void __iomem * addr)
 {
 	IO_COND(addr, /* nothing */, iounmap(addr));
 }
-EXPORT_SYMBOL(pci_iomap);
 EXPORT_SYMBOL(pci_iounmap);
 #endif /* CONFIG_PCI */