PCI: Add pci_iounmap

In case if any architecture selects CONFIG_GENERIC_PCI_IOMAP and not
CONFIG_GENERIC_IOMAP, then the pci_iounmap function is reduced to a NULL
function. Due to this the managed release variants or even the explicit
pci_iounmap calls doesn't really remove the mappings.

This issue is seen on an arm64 based system. arm64 by default selects
only CONFIG_GENERIC_PCI_IOMAP and not CONFIG_GENERIC_IOMAP from this
'commit cb61f67 ("ARM64: use GENERIC_PCI_IOMAP")'

Simple bind/unbind test of any pci driver using pcim_iomap/pci_iomap,
would lead to the following error message after long hour tests

"allocation failed: out of vmalloc space - use vmalloc=<size> to
increase size."

Signed-off-by: George Cherian <george.cherian@marvell.com>

include/asm-generic/io.h

@@ -915,12 +915,16 @@ static inline void iowrite64_rep(volatile void __iomem *addr,
 struct pci_dev;
 extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
 
+#ifdef CONFIG_GENERIC_PCI_IOMAP
+extern void pci_iounmap(struct pci_dev *dev, void __iomem *p);
+#else
 #ifndef pci_iounmap
 #define pci_iounmap pci_iounmap
 static inline void pci_iounmap(struct pci_dev *dev, void __iomem *p)
 {
 }
 #endif
+#endif /* CONFIG_GENERIC_PCI_IOMAP */
 #endif /* CONFIG_GENERIC_IOMAP */
 
 /*

lib/pci_iomap.c

@@ -134,4 +134,13 @@ void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long maxlen)
 	return pci_iomap_wc_range(dev, bar, 0, maxlen);
 }
 EXPORT_SYMBOL_GPL(pci_iomap_wc);
+
+#ifndef CONFIG_GENERIC_IOMAP
+#define pci_iounmap pci_iounmap
+void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
+{
+	iounmap(addr);
+}
+EXPORT_SYMBOL(pci_iounmap);
+#endif
 #endif /* CONFIG_PCI */