[PATCH v4 2/7] dma: Add simple dma_noop_mmap

From: Vladimir Murzin
Date: Mon Apr 24 2017 - 06:17:47 EST


This patch adds a simple implementation of mmap to dma_noop_ops.

Cc: Joerg Roedel <jroedel@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Reported-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx>
Tested-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx>
Tested-by: Andras Szemzo <sza@xxxxxx>
Tested-by: Alexandre TORGUE <alexandre.torgue@xxxxxx>
Signed-off-by: Vladimir Murzin <vladimir.murzin@xxxxxxx>
---
lib/dma-noop.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/lib/dma-noop.c b/lib/dma-noop.c
index ff4ef5e..0acc3f6 100644
--- a/lib/dma-noop.c
+++ b/lib/dma-noop.c
@@ -66,6 +66,26 @@ static int dma_noop_supported(struct device *dev, u64 mask)
return 1;
}

+static int dma_noop_mmap(struct device *dev, struct vm_area_struct *vma,
+ void *cpu_addr, dma_addr_t dma_addr, size_t size,
+ unsigned long attrs)
+{
+ unsigned long user_count = vma_pages(vma);
+ unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+ unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr));
+ unsigned long off = vma->vm_pgoff;
+ int ret = -ENXIO;
+
+ if (off < count && user_count <= (count - off)) {
+ ret = remap_pfn_range(vma, vma->vm_start,
+ pfn + off,
+ user_count << PAGE_SHIFT,
+ vma->vm_page_prot);
+ }
+
+ return ret;
+}
+
const struct dma_map_ops dma_noop_ops = {
.alloc = dma_noop_alloc,
.free = dma_noop_free,
@@ -73,6 +93,7 @@ const struct dma_map_ops dma_noop_ops = {
.map_sg = dma_noop_map_sg,
.mapping_error = dma_noop_mapping_error,
.dma_supported = dma_noop_supported,
+ .mmap = dma_noop_mmap,
};

EXPORT_SYMBOL(dma_noop_ops);
--
2.0.0