[RFC][PATCH 2/3] dma-buf: heaps: Allow adding specified non-default CMA heaps

[John Stultz]

In earlier versions of the dmabuf CMA heap, we added all CMA
areas as CMA heaps. Andrew noted this might not be desired,
and so we changed the code to only add the default CMA area.

This patch extends the earlier effort so that devices can
specifiy which CMA areas they want to add as dmabuf heaps via
DT, and we'll only add those.

This allows multiple CMA areas to be exported via the dmabuf
heaps interface.

Cc: Rob Herring <robh+dt at kernel.org>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Laura Abbott <labbott at redhat.com>
Cc: Benjamin Gaignard <benjamin.gaignard at linaro.org>
Cc: Sumit Semwal <sumit.semwal at linaro.org>
Cc: Liam Mark <lmark at codeaurora.org>
Cc: Pratik Patel <pratikp at codeaurora.org>
Cc: Brian Starkey <Brian.Starkey at arm.com>
Cc: Andrew F. Davis <afd at ti.com>
Cc: Chenbo Feng <fengc at google.com>
Cc: Alistair Strachan <astrachan at google.com>
Cc: Sandeep Patil <sspatil at google.com>
Cc: Hridya Valsaraju <hridya at google.com>
Cc: devicetree at vger.kernel.org
Cc: dri-devel at lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz at linaro.org>
---
 drivers/dma-buf/heaps/cma_heap.c | 38 ++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index 064926b5d735..0d5231a1e561 100644
--- a/drivers/dma-buf/heaps/cma_heap.c
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -15,6 +15,9 @@
 #include <linux/errno.h>
 #include <linux/highmem.h>
 #include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/scatterlist.h>
 #include <linux/sched/signal.h>
@@ -174,5 +177,40 @@ static int add_default_cma_heap(void)
 	return ret;
 }
 module_init(add_default_cma_heap);
+
+static int cma_heaps_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct cma *cma_area;
+	int ret;
+
+	ret = of_reserved_mem_device_init_by_idx(&pdev->dev, np, 0);
+	if (ret) {
+		pr_err("Error %s(): of_reserved_mem_device_init_by_idx failed!\n", __func__);
+		return ret;
+	}
+
+	cma_area = dev_get_cma_area(&pdev->dev);
+	if (cma_area)
+		ret = __add_cma_heap(cma_area, NULL);
+
+	return ret;
+}
+
+static const struct of_device_id cma_heap_dt_ids[] = {
+	{ .compatible = "dmabuf-heap-cma" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, cma_heap_dt_ids);
+
+static struct platform_driver cma_heaps_driver = {
+	.driver	= {
+		.name		= "CMA Heaps",
+		.of_match_table	= cma_heap_dt_ids,
+	},
+	.probe	= cma_heaps_probe,
+};
+
+module_platform_driver(cma_heaps_driver);
 MODULE_DESCRIPTION("DMA-BUF CMA Heap");
 MODULE_LICENSE("GPL v2");
-- 
2.17.1