linux-kernel - [PATCH 2/3] iommu/io-pgtable-arm: Add IOMMU

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Message-Id: <3f589e7de3f9fa93e84c83420c5270c546a0c368.1610372717.git.saiprakash.ranjan@codeaurora.org>
Date:   Mon, 11 Jan 2021 19:45:04 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Rob Clark <robdclark@...il.com>,
        Akhil P Oommen <akhilpo@...eaurora.org>,
        isaacm@...eaurora.org
Cc:     iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        freedreno <freedreno@...ts.freedesktop.org>,
        Kristian H Kristensen <hoegsberg@...gle.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: [PATCH 2/3] iommu/io-pgtable-arm: Add IOMMU_LLC page protection flag

Add a new page protection flag IOMMU_LLC which can be used
by non-coherent masters to set cacheable memory attributes
for an outer level of cache called as last-level cache or
system cache. Initial user of this page protection flag is
the adreno gpu and then can later be used by other clients
such as video where this can be used for per-buffer based
mapping.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
---
 drivers/iommu/io-pgtable-arm.c | 3 +++
 include/linux/iommu.h          | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 7439ee7fdcdb..ebe653ef601b 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -415,6 +415,9 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
 		else if (prot & IOMMU_CACHE)
 			pte |= (ARM_LPAE_MAIR_ATTR_IDX_CACHE
 				<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
+		else if (prot & IOMMU_LLC)
+			pte |= (ARM_LPAE_MAIR_ATTR_IDX_INC_OCACHE
+				<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
 	}
 
 	if (prot & IOMMU_CACHE)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ffaa389ea128..1f82057df531 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -31,6 +31,12 @@
  * if the IOMMU page table format is equivalent.
  */
 #define IOMMU_PRIV	(1 << 5)
+/*
+ * Non-coherent masters can use this page protection flag to set cacheable
+ * memory attributes for only a transparent outer level of cache, also known as
+ * the last-level or system cache.
+ */
+#define IOMMU_LLC	(1 << 6)
 
 struct iommu_ops;
 struct iommu_group;
-- 
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