PCI: Add pci_unmap_iospace() to unmap I/O resources

BugLink: https://bugs.launchpad.net/bugs/1797092

Add pci_unmap_iospace() to undo what pci_remap_iospace() did.

This is needed to support hotplug removal of host bridges that use
pci_remap_iospace().

[bhelgaas: changelog]
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
(backported from commit 4d3f1384)
[ dannf: Offset fixup in #include section ]
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

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-generic/pci-bridge.h>
 #include <asm/setup.h>
 #include <linux/aer.h>
@@ -3180,6 +3181,23 @@ 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));
+#endif
+}
+
 static void __pci_set_master(struct pci_dev *dev, bool enable)
 {
 	u16 old_cmd, cmd;

include/linux/pci.h

@@ -1156,6 +1156,7 @@ int pci_register_io_range(phys_addr_t addr, resource_size_t size);
 unsigned long pci_address_to_pio(phys_addr_t addr);
 phys_addr_t pci_pio_to_address(unsigned long pio);
 int pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr);
+void pci_unmap_iospace(struct resource *res);
 
 static inline pci_bus_addr_t pci_bus_address(struct pci_dev *pdev, int bar)
 {