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Subject[RFC][PATCH 4/5 v2] dma-buf: heaps: Add CMA heap to dmabuf heapss
Date
This adds a CMA heap, which allows userspace to allocate
a dma-buf of contiguous memory out of a CMA region.

This code is an evolution of the Android ION implementation, so
thanks to its original author and maintainters:
Benjamin Gaignard, Laura Abbott, and others!

Cc: Laura Abbott <labbott@redhat.com>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Andrew F. Davis <afd@ti.com>
Cc: Chenbo Feng <fengc@google.com>
Cc: Alistair Strachan <astrachan@google.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
v2:
* Switch allocate to return dmabuf fd
* Simplify init code
* Checkpatch fixups
---
drivers/dma-buf/heaps/Kconfig | 8 ++
drivers/dma-buf/heaps/Makefile | 1 +
drivers/dma-buf/heaps/cma_heap.c | 164 +++++++++++++++++++++++++++++++++++++++
3 files changed, 173 insertions(+)
create mode 100644 drivers/dma-buf/heaps/cma_heap.c

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index 2050527..a5eef06 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -4,3 +4,11 @@ config DMABUF_HEAPS_SYSTEM
help
Choose this option to enable the system dmabuf heap. The system heap
is backed by pages from the buddy allocator. If in doubt, say Y.
+
+config DMABUF_HEAPS_CMA
+ bool "DMA-BUF CMA Heap"
+ depends on DMABUF_HEAPS && DMA_CMA
+ help
+ Choose this option to enable dma-buf CMA heap. This heap is backed
+ by the Contiguous Memory Allocator (CMA). If your system has these
+ regions, you should say Y here.
diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
index d1808ec..6e54cde 100644
--- a/drivers/dma-buf/heaps/Makefile
+++ b/drivers/dma-buf/heaps/Makefile
@@ -1,3 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
obj-y += heap-helpers.o
obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o
+obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o
diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
new file mode 100644
index 0000000..33c18ec
--- /dev/null
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DMABUF CMA heap exporter
+ *
+ * Copyright (C) 2012, 2019 Linaro Ltd.
+ * Author: <benjamin.gaignard@linaro.org> for ST-Ericsson.
+ */
+
+#include <linux/device.h>
+#include <linux/dma-buf.h>
+#include <linux/dma-heap.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/cma.h>
+#include <linux/scatterlist.h>
+#include <linux/highmem.h>
+
+#include "heap-helpers.h"
+
+struct cma_heap {
+ struct dma_heap heap;
+ struct cma *cma;
+};
+
+
+#define to_cma_heap(x) container_of(x, struct cma_heap, heap)
+
+
+static void cma_heap_free(struct heap_helper_buffer *buffer)
+{
+ struct cma_heap *cma_heap = to_cma_heap(buffer->heap_buffer.heap);
+ struct page *pages = buffer->priv_virt;
+ unsigned long nr_pages;
+
+ nr_pages = PAGE_ALIGN(buffer->heap_buffer.size) >> PAGE_SHIFT;
+
+ /* release memory */
+ cma_release(cma_heap->cma, pages, nr_pages);
+ /* release sg table */
+ sg_free_table(buffer->sg_table);
+ kfree(buffer->sg_table);
+ kfree(buffer);
+}
+
+/* dmabuf heap CMA operations functions */
+static int cma_heap_allocate(struct dma_heap *heap,
+ unsigned long len,
+ unsigned long flags)
+{
+ struct cma_heap *cma_heap = to_cma_heap(heap);
+ struct heap_helper_buffer *helper_buffer;
+ struct sg_table *table;
+ struct page *pages;
+ size_t size = PAGE_ALIGN(len);
+ unsigned long nr_pages = size >> PAGE_SHIFT;
+ unsigned long align = get_order(size);
+ DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+ struct dma_buf *dmabuf;
+ int ret = -ENOMEM;
+
+ if (align > CONFIG_CMA_ALIGNMENT)
+ align = CONFIG_CMA_ALIGNMENT;
+
+ helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL);
+ if (!helper_buffer)
+ return -ENOMEM;
+
+ INIT_HEAP_HELPER_BUFFER(helper_buffer, cma_heap_free);
+ helper_buffer->heap_buffer.flags = flags;
+ helper_buffer->heap_buffer.heap = heap;
+ helper_buffer->heap_buffer.size = len;
+
+
+ pages = cma_alloc(cma_heap->cma, nr_pages, align, false);
+ if (!pages)
+ goto free_buf;
+
+ if (PageHighMem(pages)) {
+ unsigned long nr_clear_pages = nr_pages;
+ struct page *page = pages;
+
+ while (nr_clear_pages > 0) {
+ void *vaddr = kmap_atomic(page);
+
+ memset(vaddr, 0, PAGE_SIZE);
+ kunmap_atomic(vaddr);
+ page++;
+ nr_clear_pages--;
+ }
+ } else {
+ memset(page_address(pages), 0, size);
+ }
+
+ table = kmalloc(sizeof(*table), GFP_KERNEL);
+ if (!table)
+ goto free_cma;
+
+ ret = sg_alloc_table(table, 1, GFP_KERNEL);
+ if (ret)
+ goto free_table;
+
+ sg_set_page(table->sgl, pages, size, 0);
+
+ /* create the dmabuf */
+ exp_info.ops = &heap_helper_ops;
+ exp_info.size = len;
+ exp_info.flags = O_RDWR;
+ exp_info.priv = &helper_buffer->heap_buffer;
+ dmabuf = dma_buf_export(&exp_info);
+ if (IS_ERR(dmabuf)) {
+ ret = PTR_ERR(dmabuf);
+ goto free_table;
+ }
+
+ helper_buffer->heap_buffer.dmabuf = dmabuf;
+ helper_buffer->priv_virt = pages;
+ helper_buffer->sg_table = table;
+
+ ret = dma_buf_fd(dmabuf, O_CLOEXEC);
+ if (ret < 0) {
+ dma_buf_put(dmabuf);
+ /* just return, as put will call release and that will free */
+ return ret;
+ }
+
+ return ret;
+free_table:
+ kfree(table);
+free_cma:
+ cma_release(cma_heap->cma, pages, nr_pages);
+free_buf:
+ kfree(helper_buffer);
+ return ret;
+}
+
+static struct dma_heap_ops cma_heap_ops = {
+ .allocate = cma_heap_allocate,
+};
+
+static int __add_cma_heaps(struct cma *cma, void *data)
+{
+ struct cma_heap *cma_heap;
+
+ cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
+
+ if (!cma_heap)
+ return -ENOMEM;
+
+ cma_heap->heap.name = cma_get_name(cma);
+ cma_heap->heap.ops = &cma_heap_ops;
+ cma_heap->cma = cma;
+
+ dma_heap_add(&cma_heap->heap);
+
+ return 0;
+}
+
+static int add_cma_heaps(void)
+{
+ cma_for_each_area(__add_cma_heaps, NULL);
+ return 0;
+}
+device_initcall(add_cma_heaps);
--
2.7.4
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