Can you explain why it is necessary? Can you also include a client driver patches that uses this new attribute?
Including the patches that uses this attribute would make it easy to upstream.
-KR
-----Original Message-----
From: Ashish Mhetre <amhetre@xxxxxxxxxx>
Sent: Tuesday, August 4, 2020 12:53 AM
To: Krishna Reddy <vdumpa@xxxxxxxxxx>; Thierry Reding <treding@xxxxxxxxxx>; Jonathan Hunter <jonathanh@xxxxxxxxxx>; Stephen Warren <swarren@xxxxxxxxxx>; Sachin Nikam <Snikam@xxxxxxxxxx>
Cc: SW-Mobile-Linux-Upstreaming <SW-Mobile-Linux-Upstreaming@xxxxxxxxxxxxxxxxxxx>; SW-Mobile-Memory-Core <SW-Mobile-Memory-Core@xxxxxxxxxxxxxxxxxxx>; linux-tegra@xxxxxxxxxxxxxxx; Ashish Mhetre <amhetre@xxxxxxxxxx>
Subject: [PATCH] iommu/dma: Add support for mapping memory as device memory
Add DMA_ATTRS_DEVICE_MAP attribute to support mapping memory as device memory.
Signed-off-by: Ashish Mhetre <amhetre@xxxxxxxxxx>
---
drivers/iommu/dma-iommu.c | 3 +++
include/linux/dma-mapping.h | 6 ++++++
2 files changed, 9 insertions(+)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 65ac889..0e411ef 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -388,6 +388,9 @@ static int dma_info_to_prot(enum dma_data_direction dir, bool coherent,
if (attrs & DMA_ATTR_PRIVILEGED)
prot |= IOMMU_PRIV;
+ if (attrs & DMA_ATTR_DEVICE_MAP)
+ prot |= IOMMU_MMIO;
+
switch (dir) {
case DMA_BIDIRECTIONAL:
return prot | IOMMU_READ | IOMMU_WRITE; diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 330ad58..b0cb1b3 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -68,6 +68,12 @@
#define DMA_ATTR_PRIVILEGED (1UL << 9)
/*
+ * DMA_ATTR_DEVICE_MAP: This specifies DMA-mapping subsystem to map
+memory
+ * as device memory.
+ */
+#define DMA_ATTR_DEVICE_MAP (1UL << 10)
+
+/*
* A dma_addr_t can hold any valid DMA or bus address for the platform.
* It can be given to a device to use as a DMA source or target. A CPU cannot
* reference a dma_addr_t directly because there may be translation between
--
2.7.4
