linux-kernel - [PATCH v3 1/8] iommu: Add MMIO mapping type

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Message-Id: <1455065878-11906-2-git-send-email-niklas.soderlund+renesas@ragnatech.se>
Date:	Wed, 10 Feb 2016 01:57:51 +0100
From:	Niklas Söderlund 
	<niklas.soderlund+renesas@...natech.se>
To:	linux-renesas-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org, iommu@...ts.linux-foundation.org
Cc:	robin.murphy@....com, vinod.koul@...el.com,
	laurent.pinchart@...asonboard.com, geert+renesas@...der.be,
	linus.walleij@...aro.org, dan.j.williams@...el.com, arnd@...db.de,
	linux-arch@...r.kernel.org
Subject: [PATCH v3 1/8] iommu: Add MMIO mapping type

From: Robin Murphy <robin.murphy@....com>

On some platforms, MMIO regions might need slightly different treatment
compared to mapping regular memory; add the notion of MMIO mappings to
the IOMMU API's memory type flags, so that callers can let the IOMMU
drivers know to do the right thing.

Signed-off-by: Robin Murphy <robin.murphy@....com>
Acked-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
---
 drivers/iommu/io-pgtable-arm.c | 4 +++-
 include/linux/iommu.h          | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 381ca5a..3ff4f87 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -364,7 +364,9 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
 			pte |= ARM_LPAE_PTE_HAP_READ;
 		if (prot & IOMMU_WRITE)
 			pte |= ARM_LPAE_PTE_HAP_WRITE;
-		if (prot & IOMMU_CACHE)
+		if (prot & IOMMU_MMIO)
+			pte |= ARM_LPAE_PTE_MEMATTR_DEV;
+		else if (prot & IOMMU_CACHE)
 			pte |= ARM_LPAE_PTE_MEMATTR_OIWB;
 		else
 			pte |= ARM_LPAE_PTE_MEMATTR_NC;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index a5c539f..34b6432 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -30,6 +30,7 @@
 #define IOMMU_WRITE	(1 << 1)
 #define IOMMU_CACHE	(1 << 2) /* DMA cache coherency */
 #define IOMMU_NOEXEC	(1 << 3)
+#define IOMMU_MMIO	(1 << 4) /* e.g. things like MSI doorbells */
 
 struct iommu_ops;
 struct iommu_group;
-- 
2.7.1