Commit 493c9b68 authored by Thierry Reding's avatar Thierry Reding Committed by Ulf Hansson
Browse files

iommu/tegra: Add tegra_dev_iommu_get_stream_id() helper 



Access to the internals of struct iommu_fwspec by non-IOMMU drivers is
discouraged. Many drivers for Tegra SoCs, however, need access to their
IOMMU stream IDs so that they can be programmed into various hardware
registers.

Formalize this access into a common helper to make it easier to audit
and maintain.

Acked-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20221206165945.3551774-3-thierry.reding@gmail.com


Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent 495b637f

include/linux/iommu.h

+21 −0
Original line number Diff line number Diff line
@@ -1103,4 +1103,25 @@ static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc, struct msi_m 


#endif	/* CONFIG_IOMMU_DMA */



/*

 * Newer generations of Tegra SoCs require devices' stream IDs to be directly programmed into

 * some registers. These are always paired with a Tegra SMMU or ARM SMMU, for which the contents

 * of the struct iommu_fwspec are known. Use this helper to formalize access to these internals.

 */

#define TEGRA_STREAM_ID_BYPASS 0x7f



static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream_id)

{

#ifdef CONFIG_IOMMU_API

	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);



	if (fwspec && fwspec->num_ids == 1) {

		*stream_id = fwspec->ids[0] & 0xffff;

		return true;

	}

#endif



	return false;

}



#endif /* __LINUX_IOMMU_H */