Multiple platform devices may be placed in the same IOMMU group because
they cannot be isolated from each other. These devices must either be
entirely under kernel control or userspace control, never a mixture. This
checks and sets DMA ownership during driver binding, and release the
ownership during driver unbinding.

Driver may set a new flag (suppress_auto_claim_dma_owner) to disable auto
claiming DMA_OWNER_DMA_API ownership in the binding process. For instance,
the userspace framework drivers (vfio etc.) which need to manually claim
DMA_OWNER_PRIVATE_DOMAIN_USER when assigning a device to userspace.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 include/linux/platform_device.h |  1 +
 drivers/base/platform.c         | 30 +++++++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 4381c34af7e0..f3926be7582f 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h

@@ -210,6 +210,7 @@ struct platform_driver {
 	struct device_driver driver;
 	const struct platform_device_id *id_table;
 	bool prevent_deferred_probe;
+	bool suppress_auto_claim_dma_owner;