[PATCHv2] PCI: Add pci_iounmap

[George Cherian]

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 cb61f6769b88 ("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@xxxxxxxxxxx>
---
* Changes from v1
	- Fix the 0-day compilation error.
	- Mark the lib/iomap pci_iounmap call as weak incase 
	  if any architecture have there own implementation.

 include/asm-generic/io.h |  4 ++++
 lib/pci_iomap.c          | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index dabf8cb7203b..5986b37226b7 100644
--- a/include/asm-generic/io.h
+++ b/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 */
 
 /*
diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
index 2d3eb1cb73b8..ecd1eb3f6c25 100644
--- a/lib/pci_iomap.c
+++ b/lib/pci_iomap.c
@@ -134,4 +134,14 @@ 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 __weak pci_iounmap(struct pci_dev *dev, void __iomem *addr);
+void __weak pci_iounmap(struct pci_dev *dev, void __iomem *addr)
+{
+	iounmap(addr);
+}
+EXPORT_SYMBOL(pci_iounmap);
+#endif
 #endif /* CONFIG_PCI */
-- 
2.25.1