[PATCH v6 2/2] dma-buf: heaps: cma: Create CMA heap for each CMA reserved region

[Maxime Ripard]

Aside from the main CMA region, it can be useful to allow userspace to
allocate from the other CMA reserved regions.

Indeed, those regions can have specific properties that can be useful to
a specific us-case.

For example, one of them platform I've been with has ECC enabled on the
entire memory but for a specific region. Using that region to allocate
framebuffers can be particular beneficial because enabling the ECC has a
performance and memory footprint cost.

Thus, exposing these regions as heaps user-space can allocate from and
import wherever needed allows to cover that use-case.

For now, only shared-dma-pools regions with the reusable property (ie,
backed by CMA) are supported, but eventually we'll want to support other
DMA pools types.

Signed-off-by: Maxime Ripard <mripard at kernel.org>
---
 drivers/dma-buf/heaps/cma_heap.c | 52 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index 0df007111975447d555714d61ead9699287fd65a..31a18683ee25788a800f3f878fd958718a930ff7 100644
--- a/drivers/dma-buf/heaps/cma_heap.c
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -19,10 +19,12 @@
 #include <linux/err.h>
 #include <linux/highmem.h>
 #include <linux/io.h>
 #include <linux/mm.h>
 #include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 
 #define DEFAULT_CMA_NAME "default_cma_region"
@@ -421,7 +423,55 @@ static int __init add_default_cma_heap(void)
 				ERR_PTR(ret));
 	}
 
 	return 0;
 }
-module_init(add_default_cma_heap);
+
+static int __init add_cma_heaps(void)
+{
+	struct device_node *rmem_node;
+	struct device_node *node;
+	int ret;
+
+	ret = add_default_cma_heap();
+	if (ret)
+		return ret;
+
+	rmem_node = of_find_node_by_path("/reserved-memory");
+	if (!rmem_node)
+		goto out;
+
+	for_each_child_of_node(rmem_node, node) {
+		struct reserved_mem *rmem;
+		struct cma *cma;
+
+		rmem = of_reserved_mem_lookup(node);
+		if (!rmem) {
+			ret = -EINVAL;
+			goto err_put_node;
+		}
+
+		if (!of_reserved_mem_is_contiguous(rmem))
+			continue;
+
+		cma = rmem->priv;
+		if (!cma) {
+			ret = -EINVAL;
+			goto err_put_node;
+		}
+
+		ret = __add_cma_heap(cma, of_node_full_name(node));
+		if (ret)
+			goto err_put_node;
+	}
+
+out:
+	of_node_put(rmem_node);
+	return 0;
+
+err_put_node:
+	of_node_put(rmem_node);
+	return ret;
+}
+
+module_init(add_cma_heaps);
 MODULE_DESCRIPTION("DMA-BUF CMA Heap");

-- 
2.50.0