drm/i915: setup io-mapping for LMEM

Create an io-mapping to describe the CPU aperture for lmem.
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191025153728.23689-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_region_lmem.c

@@ -9,8 +9,32 @@
 #include "gem/i915_gem_region.h"
 #include "intel_region_lmem.h"
 
+static void
+region_lmem_release(struct intel_memory_region *mem)
+{
+	io_mapping_fini(&mem->iomap);
+	intel_memory_region_release_buddy(mem);
+}
+
+static int
+region_lmem_init(struct intel_memory_region *mem)
+{
+	int ret;
+
+	if (!io_mapping_init_wc(&mem->iomap,
+				mem->io_start,
+				resource_size(&mem->region)))
+		return -EIO;
+
+	ret = intel_memory_region_init_buddy(mem);
+	if (ret)
+		io_mapping_fini(&mem->iomap);
+
+	return ret;
+}
+
 const struct intel_memory_region_ops intel_region_lmem_ops = {
-	.init = intel_memory_region_init_buddy,
-	.release = intel_memory_region_release_buddy,
+	.init = region_lmem_init,
+	.release = region_lmem_release,
 	.create_object = __i915_gem_lmem_object_create,
 };