kunit: Setup DMA masks on the kunit device

BugLink: https://bugs.launchpad.net/bugs/2060097

[ Upstream commit c5215d54dc10e801a6cefef62445a00a4c28a515 ]

Commit d393acce7b ("drm/tests: Switch to kunit devices") switched the
DRM device creation helpers from an ad-hoc implementation to the new
kunit device creation helpers introduced in commit d03c720e03 ("kunit:
Add APIs for managing devices").

However, while the DRM helpers were using a platform_device, the kunit
helpers are using a dedicated bus and device type.

That situation creates small differences in the initialisation, and one
of them is that the kunit devices do not have the DMA masks setup. In
turn, this means that we can't do any kind of DMA buffer allocation
anymore, which creates a regression on some (downstream for now) tests.

Let's set up a default DMA mask that should work on any platform to fix
it.

Fixes: d03c720e03 ("kunit: Add APIs for managing devices")
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 5a3be9ae70309f8b6057610fb496e95db1b1dd03)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

lib/kunit/device.c

@@ -10,6 +10,7 @@
  */
 
 #include <linux/device.h>
+#include <linux/dma-mapping.h>
 
 #include <kunit/test.h>
 #include <kunit/device.h>
@@ -133,6 +134,9 @@ static struct kunit_device *kunit_device_register_internal(struct kunit *test,
 		return ERR_PTR(err);
 	}
 
+	kunit_dev->dev.dma_mask = &kunit_dev->dev.coherent_dma_mask;
+	kunit_dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+
 	kunit_add_action(test, device_unregister_wrapper, &kunit_dev->dev);
 
 	return kunit_dev;