It is very useful to release I/O resources so that the same I/O resources
can be allocated again (pci_remap_iospace), like in PCI hotplug removal
scenario. Therefore this patch implements new pci_unmap_iospace call which
unmaps I/O space as the symmetry to pci_remap_iospace.

Signed-off-by: Sinan Kaya <redacted>
Signed-off-by: Tomasz Nowicki <redacted>
---
 drivers/pci/pci.c   | 24 ++++++++++++++++++++++++
 include/linux/pci.h |  1 +
 2 files changed, 25 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index bc0c914..ff97a0b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c

@@ -25,6 +25,7 @@
 #include <linux/device.h>
 #include <linux/pm_runtime.h>
 #include <linux/pci_hotplug.h>
+#include <linux/vmalloc.h>
 #include <asm/setup.h>
 #include <linux/aer.h>
 #include "pci.h"

@@ -3167,6 +3168,29 @@ int __weak pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr)
 #endif
 }

+/**
+ *     pci_unmap_iospace - Unmap the memory mapped I/O space
+ *     @res: resource to be unmapped
+ *
+ *     Unmap the CPU virtual address @res from virtual address space.
+ *     Only architectures that have memory mapped IO functions defined
+ *     (and the PCI_IOBASE value defined) should call this function.
+ */
+void  pci_unmap_iospace(struct resource *res)
+{
+#if defined(PCI_IOBASE) && defined(CONFIG_MMU)
+       unsigned long vaddr = (unsigned long)PCI_IOBASE + res->start;
+
+       unmap_kernel_range(vaddr, resource_size(res));
+#else
+       /*
+        * This architecture does not have memory mapped I/O space,
+        * so this function should never be called.
+        */
+       WARN_ONCE(1, "This architecture does not support memory mapped I/O\n");
+#endif
+}