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Subject[PATCH 1/2] drivers: dma-coherent: Add support for default DMA coherent pool
Date
From: "George G. Davis" <george_davis@mentor.com>

Use concept similar to the default CMA region for DMA coherent pools.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Mark Craske <Mark_Craske@mentor.com>
Signed-off-by: Vitaly Kuzmichev <Vitaly_Kuzmichev@mentor.com>
---
.../bindings/reserved-memory/reserved-memory.txt | 2 ++
drivers/base/dma-coherent.c | 29 ++++++++++++++++------
2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
index 3da0ebd..ed9a051 100644
--- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
@@ -67,6 +67,8 @@ reusable (optional) - empty property
Linux implementation note:
- If a "linux,cma-default" property is present, then Linux will use the
region for the default pool of the contiguous memory allocator.
+- If a "linux,dma-default" property is present, then Linux will use the
+ region for the default pool of the DMA coherent memory allocator.

Device node references to reserved memory
-----------------------------------------
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index 640a7e6..a0b0f2b 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -18,6 +18,19 @@ struct dma_coherent_mem {
spinlock_t spinlock;
};

+static struct dma_coherent_mem **dma_coherent_default_area;
+
+static inline struct dma_coherent_mem *dev_get_dma_area(struct device *dev)
+{
+ if (dev && dev->dma_mem)
+ return dev->dma_mem;
+#ifdef CONFIG_CMA
+ if (dev && dev->cma_area)
+ return NULL;
+#endif
+ return dma_coherent_default_area ? *dma_coherent_default_area : NULL;
+}
+
static bool dma_init_coherent_memory(
phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags,
struct dma_coherent_mem **mem)
@@ -111,7 +124,7 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,

void dma_release_declared_memory(struct device *dev)
{
- struct dma_coherent_mem *mem = dev->dma_mem;
+ struct dma_coherent_mem *mem = dev_get_dma_area(dev);

if (!mem)
return;
@@ -123,7 +136,7 @@ void dma_release_declared_memory(struct device *dev)
void *dma_mark_declared_memory_occupied(struct device *dev,
dma_addr_t device_addr, size_t size)
{
- struct dma_coherent_mem *mem = dev->dma_mem;
+ struct dma_coherent_mem *mem = dev_get_dma_area(dev);
unsigned long flags;
int pos, err;

@@ -167,9 +180,7 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
int pageno;
int dma_memory_map;

- if (!dev)
- return 0;
- mem = dev->dma_mem;
+ mem = dev_get_dma_area(dev);
if (!mem)
return 0;

@@ -223,7 +234,7 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
*/
int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
{
- struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+ struct dma_coherent_mem *mem = dev_get_dma_area(dev);

if (mem && vaddr >= mem->virt_base && vaddr <
(mem->virt_base + (mem->size << PAGE_SHIFT))) {
@@ -257,7 +268,7 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
void *vaddr, size_t size, int *ret)
{
- struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+ struct dma_coherent_mem *mem = dev_get_dma_area(dev);

if (mem && vaddr >= mem->virt_base && vaddr + size <=
(mem->virt_base + (mem->size << PAGE_SHIFT))) {
@@ -329,6 +340,10 @@ static int __init rmem_dma_setup(struct reserved_mem *rmem)
}
#endif

+ if (of_get_flat_dt_prop(node, "linux,dma-default", NULL))
+ dma_coherent_default_area =
+ (struct dma_coherent_mem **)&rmem->priv;
+
rmem->ops = &rmem_dma_ops;
pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
&rmem->base, (unsigned long)rmem->size / SZ_1M);
--
1.9.1
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