kernel/resource: Introduce request_mem_region_muxed()

Support for requesting muxed memory region is implemented but not
currently callable as a macro. Add the request muxed memory
region macro.

MMIO memory accesses can be synchronized using request_mem_region() which
is already available. This call will return failure if the resource is
busy. The 'muxed' version of this macro will handle a busy resource by
using a wait queue to retry until the resource is available.
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

include/linux/ioport.h

@@ -262,6 +262,8 @@ resource_union(struct resource *r1, struct resource *r2, struct resource *r)
 #define request_muxed_region(start,n,name)	__request_region(&ioport_resource, (start), (n), (name), IORESOURCE_MUXED)
 #define __request_mem_region(start,n,name, excl) __request_region(&iomem_resource, (start), (n), (name), excl)
 #define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name), 0)
+#define request_mem_region_muxed(start, n, name) \
+	__request_region(&iomem_resource, (start), (n), (name), IORESOURCE_MUXED)
 #define request_mem_region_exclusive(start,n,name) \
 	__request_region(&iomem_resource, (start), (n), (name), IORESOURCE_EXCLUSIVE)
 #define rename_region(region, newname) do { (region)->name = (newname); } while (0)