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authorMitchel Humpherys <mitchelh@codeaurora.org>2017-01-06 18:58:11 +0530
committerWill Deacon <will.deacon@arm.com>2017-01-19 15:56:19 +0000
commitb2fb366425ceb85dca56afa538257ec5a2c4f6d1 (patch)
tree253f2d37b4818737e2814e39a866e564f4d0cc20 /Documentation/DMA-attributes.txt
parent5baf1e9d0bb223b086c422b880359c9fe2ee1476 (diff)
downloadlinux-b2fb366425ceb85dca56afa538257ec5a2c4f6d1.tar.bz2
common: DMA-mapping: add DMA_ATTR_PRIVILEGED attribute
This patch adds the DMA_ATTR_PRIVILEGED attribute to the DMA-mapping subsystem. Some advanced peripherals such as remote processors and GPUs perform accesses to DMA buffers in both privileged "supervisor" and unprivileged "user" modes. This attribute is used to indicate to the DMA-mapping subsystem that the buffer is fully accessible at the elevated privilege level (and ideally inaccessible or at least read-only at the lesser-privileged levels). Cc: linux-doc@vger.kernel.org Reviewed-by: Robin Murphy <robin.murphy@arm.com> Tested-by: Robin Murphy <robin.murphy@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'Documentation/DMA-attributes.txt')
-rw-r--r--Documentation/DMA-attributes.txt10
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt
index 98bf7ac29aad..44c6bc496eee 100644
--- a/Documentation/DMA-attributes.txt
+++ b/Documentation/DMA-attributes.txt
@@ -143,3 +143,13 @@ So, this provides a way for drivers to avoid those error messages on calls
where allocation failures are not a problem, and shouldn't bother the logs.
NOTE: At the moment DMA_ATTR_NO_WARN is only implemented on PowerPC.
+
+DMA_ATTR_PRIVILEGED
+------------------------------
+
+Some advanced peripherals such as remote processors and GPUs perform
+accesses to DMA buffers in both privileged "supervisor" and unprivileged
+"user" modes. This attribute is used to indicate to the DMA-mapping
+subsystem that the buffer is fully accessible at the elevated privilege
+level (and ideally inaccessible or at least read-only at the
+lesser-privileged levels).