linux-kernel - [PATCH] dma-buf: heaps: Introduce dma_heap_add

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Date:   Fri, 17 Jul 2020 10:10:08 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Sumit Semwal <sumit.semwal@...aro.org>,
        "Andrew F . Davis" <afd@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Liam Mark <lmark@...eaurora.org>,
        Laura Abbott <labbott@...hat.com>,
        Brian Starkey <Brian.Starkey@....com>,
        John Stultz <john.stultz@...aro.org>,
        Christian Koenig <christian.koenig@....com>
Cc:     linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Subject: [PATCH] dma-buf: heaps: Introduce dma_heap_add_cma() for non-default CMA heap

Current dma-buf heaps can handle only default CMA. This introduces
dma_heap_add_cma() function to attach CMA heaps that belongs to a device.

At first, the driver calls of_reserved_mem_device_init() to set
memory-region property associated with reserved-memory defined as CMA
to the device. And when the driver calls this dma_heap_add_cma(),
the CMA will be added to dma-buf heaps.

For example, prepare CMA node named "linux,cma@...00000" and
specify the node for memory-region property. After the above calls
in the driver, a device file "/dev/dma_heap/linux,cma@...00000"
associated with the CMA become available as dma-buf heaps.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
---
 drivers/dma-buf/heaps/cma_heap.c | 12 ++++++++++++
 include/linux/dma-heap.h         |  9 +++++++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index 626cf7f..5d2442e 100644
--- a/drivers/dma-buf/heaps/cma_heap.c
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -162,6 +162,18 @@ static int __add_cma_heap(struct cma *cma, void *data)
 	return 0;
 }
 
+/* add device CMA heap to dmabuf heaps */
+int dma_heap_add_cma(struct device *dev)
+{
+	struct cma *cma = dev_get_cma_area(dev);
+
+	if (!cma)
+		return -ENOMEM;
+
+	return __add_cma_heap(cma, NULL);
+}
+EXPORT_SYMBOL_GPL(dma_heap_add_cma);
+
 static int add_default_cma_heap(void)
 {
 	struct cma *default_cma = dev_get_cma_area(NULL);
diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h
index 454e354..16bec7d 100644
--- a/include/linux/dma-heap.h
+++ b/include/linux/dma-heap.h
@@ -56,4 +56,13 @@ void *dma_heap_get_drvdata(struct dma_heap *heap);
  */
 struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info);
 
+#ifdef CONFIG_DMABUF_HEAPS_CMA
+/**
+ * dma_heap_add_cma - adds a device CMA heap to dmabuf heaps
+ * @dev:	device with a CMA heap to register
+ */
+int dma_heap_add_cma(struct device *dev);
+
+#endif /* CONFIG_DMABUF_HEAPS_CMA */
+
 #endif /* _DMA_HEAPS_H */
-- 
2.7.4