This patch introduces default coherent DMA pool similar to default CMA
area concept. To keep other users safe code kept under CONFIG_ARM.
Cc: Michal Nazarewicz <mina86 at mina86.com>
Cc: Marek Szyprowski <m.szyprowski at samsung.com>
Cc: Rob Herring <robh+dt at kernel.org>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Suggested-by: Robin Murphy <robin.murphy at arm.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard at linaro.org>
Tested-by: Andras Szemzo <sza at esh.hu>
Signed-off-by: Vladimir Murzin <vladimir.murzin at arm.com>
---
.../bindings/reserved-memory/reserved-memory.txt | 3 ++
drivers/base/dma-coherent.c | 59 +++++++++++++++++++---
2 files changed, 55 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..16291f2 100644
--- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
@@ -68,6 +68,9 @@ 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 consistent DMA allocator.
+
Device node references to reserved memory
-----------------------------------------
Regions in the /reserved-memory node may be referenced by other device
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index c59708c..0c577ea 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -18,6 +18,15 @@ struct dma_coherent_mem {
spinlock_t spinlock;
};
+static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
+
+static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
+{
+ if (dev && dev->dma_mem)
+ return dev->dma_mem;
+ return dma_coherent_default_memory;
+}
+
static inline dma_addr_t dma_get_device_base(struct device *dev,
struct dma_coherent_mem * mem)
{
@@ -91,6 +100,9 @@ static int dma_assign_coherent_memory(struct device *dev,
{
unsigned long dma_pfn_offset = mem->pfn_base - PFN_DOWN(mem->device_base);
+ if (!dev)
+ return -ENODEV;
+
if (dev->dma_mem)
return -EBUSY;
@@ -174,15 +186,12 @@ EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
int dma_alloc_from_coherent(struct device *dev, ssize_t size,
dma_addr_t *dma_handle, void **ret)
{
- struct dma_coherent_mem *mem;
+ struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
int order = get_order(size);
unsigned long flags;
int pageno;
int dma_memory_map;
- if (!dev)
- return 0;
- mem = dev->dma_mem;
if (!mem)
return 0;
@@ -236,7 +245,7 @@ EXPORT_SYMBOL(dma_alloc_from_coherent);
*/
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_coherent_memory(dev);
if (mem && vaddr >= mem->virt_base && vaddr <
(mem->virt_base + (mem->size << PAGE_SHIFT))) {
@@ -270,7 +279,7 @@ EXPORT_SYMBOL(dma_release_from_coherent);
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_coherent_memory(dev);
if (mem && vaddr >= mem->virt_base && vaddr + size <=
(mem->virt_base + (mem->size << PAGE_SHIFT))) {
@@ -300,6 +309,8 @@ EXPORT_SYMBOL(dma_mmap_from_coherent);
#include <linux/of_fdt.h>
#include <linux/of_reserved_mem.h>
+static struct reserved_mem *dma_reserved_default_memory __initdata;
+
static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
{
struct dma_coherent_mem *mem = rmem->priv;
@@ -320,7 +331,8 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
static void rmem_dma_device_release(struct reserved_mem *rmem,
struct device *dev)
{
- dev->dma_mem = NULL;
+ if (dev)
+ dev->dma_mem = NULL;
}
static const struct reserved_mem_ops rmem_dma_ops = {
@@ -340,6 +352,12 @@ static int __init rmem_dma_setup(struct reserved_mem *rmem)
pr_err("Reserved memory: regions without no-map are not yet supported\n");
return -EINVAL;
}
+
+ if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
+ WARN(dma_reserved_default_memory,
+ "Reserved memory: region for default DMA coherent area is redefined\n");
+ dma_reserved_default_memory = rmem;
+ }
#endif
rmem->ops = &rmem_dma_ops;
@@ -347,5 +365,32 @@ static int __init rmem_dma_setup(struct reserved_mem *rmem)
&rmem->base, (unsigned long)rmem->size / SZ_1M);
return 0;
}
+
+static int __init dma_init_reserved_memory(void)
+{
+ const struct reserved_mem_ops *ops;
+ int ret;
+
+ if (!dma_reserved_default_memory)
+ return -ENOMEM;
+
+ ops = dma_reserved_default_memory->ops;
+
+ /*
+ * We rely on rmem_dma_device_init() does not propagate error of
+ * dma_assign_coherent_memory() for "NULL" device.
+ */
+ ret = ops->device_init(dma_reserved_default_memory, NULL);
+
+ if (!ret) {
+ dma_coherent_default_memory = dma_reserved_default_memory->priv;
+ pr_info("DMA: default coherent area is set\n");
+ }
+
+ return ret;
+}
+
+core_initcall(dma_init_reserved_memory);
+
RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
#endif
--
2.0.0