[RFC v2 06/21] dma-mapping: set and query DMA IOVA state

[Leon Romanovsky]

From: Leon Romanovsky <leonro at nvidia.com>

Provide an option to query and set if IOMMU path can be taken.
Callers who supply range of pages can perform it only once as
the whole range is supposed to have same memory type.

Signed-off-by: Leon Romanovsky <leonro at nvidia.com>
---
 include/linux/dma-mapping.h | 12 ++++++++++++
 kernel/dma/mapping.c        | 38 +++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 6a51d8e96a9d..2c74e68b0567 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -81,6 +81,7 @@ struct dma_iova_state {
 	dma_addr_t addr;
 	size_t size;
 	enum dma_data_direction dir;
+	u8 use_iova : 1;
 };
 
 static inline void dma_init_iova_state(struct dma_iova_state *state,
@@ -169,6 +170,9 @@ void *dma_vmap_noncontiguous(struct device *dev, size_t size,
 void dma_vunmap_noncontiguous(struct device *dev, void *vaddr);
 int dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
 		size_t size, struct sg_table *sgt);
+void dma_set_iova_state(struct dma_iova_state *state, struct page *page,
+			size_t size);
+bool dma_can_use_iova(struct dma_iova_state *state);
 #else /* CONFIG_HAS_DMA */
 static inline int dma_alloc_iova_unaligned(struct dma_iova_state *state,
 					   phys_addr_t phys, size_t size)
@@ -307,6 +311,14 @@ static inline int dma_mmap_noncontiguous(struct device *dev,
 {
 	return -EINVAL;
 }
+static inline void dma_set_iova_state(struct dma_iova_state *state,
+				      struct page *page, size_t size)
+{
+}
+static inline bool dma_can_use_iova(struct dma_iova_state *state)
+{
+	return false;
+}
 #endif /* CONFIG_HAS_DMA */
 
 #if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 4cd910f27dee..16cb03d5d87d 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -6,6 +6,7 @@
  * Copyright (c) 2006  Tejun Heo <teheo at suse.de>
  */
 #include <linux/memblock.h> /* for max_pfn */
+#include <linux/memremap.h>
 #include <linux/acpi.h>
 #include <linux/dma-map-ops.h>
 #include <linux/iommu-dma.h>
@@ -15,6 +16,7 @@
 #include <linux/of_device.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
+#include <linux/cc_platform.h>
 #include "debug.h"
 #include "direct.h"
 
@@ -986,3 +988,39 @@ void dma_free_iova(struct dma_iova_state *state)
 	iommu_dma_free_iova(state);
 }
 EXPORT_SYMBOL_GPL(dma_free_iova);
+
+/**
+ * dma_set_iova_state - Set the IOVA state for the given page and size
+ * @state: IOVA state
+ * @page: page to check
+ * @size: size of the page
+ *
+ * Set the IOVA state for the given page and size. The IOVA state is set
+ * based on the device and the page.
+ */
+void dma_set_iova_state(struct dma_iova_state *state, struct page *page,
+			size_t size)
+{
+	if (!use_dma_iommu(state->dev))
+		return;
+
+	state->use_iova = iommu_can_use_iova(state->dev, page, size, state->dir);
+}
+EXPORT_SYMBOL_GPL(dma_set_iova_state);
+
+/**
+ * dma_can_use_iova - check if the device type is valid
+ *                    and won't take SWIOTLB path
+ * @state: IOVA state
+ *
+ * Return %true if the device should use swiotlb for the given buffer, else
+ * %false.
+ */
+bool dma_can_use_iova(struct dma_iova_state *state)
+{
+	if (!use_dma_iommu(state->dev))
+		return false;
+
+	return state->use_iova;
+}
+EXPORT_SYMBOL_GPL(dma_can_use_iova);
-- 
2.46.0