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    Subject[PATCH v5 4/5] dma-buf: heaps: Add CMA heap to dmabuf heaps
    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: Sumit Semwal <sumit.semwal@linaro.org>
    Cc: Liam Mark <lmark@codeaurora.org>
    Cc: Pratik Patel <pratikp@codeaurora.org>
    Cc: Brian Starkey <Brian.Starkey@arm.com>
    Cc: Vincent Donnefort <Vincent.Donnefort@arm.com>
    Cc: Sudipto Paul <Sudipto.Paul@arm.com>
    Cc: Andrew F. Davis <afd@ti.com>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Chenbo Feng <fengc@google.com>
    Cc: Alistair Strachan <astrachan@google.com>
    Cc: dri-devel@lists.freedesktop.org
    Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    Change-Id: Ic2b0c5dfc0dbaff5245bd1c50170c64b06c73051
    ---
    v2:
    * Switch allocate to return dmabuf fd
    * Simplify init code
    * Checkpatch fixups
    v3:
    * Switch to inline function for to_cma_heap()
    * Minor cleanups suggested by Brian
    * Fold in new registration style from Andrew
    * Folded in changes from Andrew to use simplified page list
    from the heap helpers
    v4:
    * Use the fd_flags when creating dmabuf fd (Suggested by
    Benjamin)
    * Use precalculated pagecount (Suggested by Andrew)
    ---
    drivers/dma-buf/heaps/Kconfig | 8 ++
    drivers/dma-buf/heaps/Makefile | 1 +
    drivers/dma-buf/heaps/cma_heap.c | 169 +++++++++++++++++++++++++++++++
    3 files changed, 178 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 205052744169..a5eef06c4226 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 d1808eca2581..6e54cdec3da0 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 000000000000..3d0ffbbd0a34
    --- /dev/null
    +++ b/drivers/dma-buf/heaps/cma_heap.c
    @@ -0,0 +1,169 @@
    +// 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;
    +};
    +
    +static void cma_heap_free(struct heap_helper_buffer *buffer)
    +{
    + struct cma_heap *cma_heap = dma_heap_get_data(buffer->heap_buffer.heap);
    + unsigned long nr_pages = buffer->pagecount;
    + struct page *pages = buffer->priv_virt;
    +
    + /* free page list */
    + kfree(buffer->pages);
    + /* release memory */
    + cma_release(cma_heap->cma, pages, nr_pages);
    + kfree(buffer);
    +}
    +
    +/* dmabuf heap CMA operations functions */
    +static int cma_heap_allocate(struct dma_heap *heap,
    + unsigned long len,
    + unsigned long fd_flags,
    + unsigned long heap_flags)
    +{
    + struct cma_heap *cma_heap = dma_heap_get_data(heap);
    + struct heap_helper_buffer *helper_buffer;
    + 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;
    + pgoff_t pg;
    +
    + 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 = heap_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);
    + }
    +
    + helper_buffer->pagecount = nr_pages;
    + helper_buffer->pages = kmalloc_array(helper_buffer->pagecount,
    + sizeof(*helper_buffer->pages),
    + GFP_KERNEL);
    + if (!helper_buffer->pages) {
    + ret = -ENOMEM;
    + goto free_cma;
    + }
    +
    + for (pg = 0; pg < helper_buffer->pagecount; pg++) {
    + helper_buffer->pages[pg] = &pages[pg];
    + if (!helper_buffer->pages[pg])
    + goto free_pages;
    + }
    +
    + /* create the dmabuf */
    + exp_info.ops = &heap_helper_ops;
    + exp_info.size = len;
    + exp_info.flags = fd_flags;
    + exp_info.priv = &helper_buffer->heap_buffer;
    + dmabuf = dma_buf_export(&exp_info);
    + if (IS_ERR(dmabuf)) {
    + ret = PTR_ERR(dmabuf);
    + goto free_pages;
    + }
    +
    + helper_buffer->heap_buffer.dmabuf = dmabuf;
    + helper_buffer->priv_virt = pages;
    +
    + ret = dma_buf_fd(dmabuf, fd_flags);
    + if (ret < 0) {
    + dma_buf_put(dmabuf);
    + /* just return, as put will call release and that will free */
    + return ret;
    + }
    +
    + return ret;
    +
    +free_pages:
    + kfree(helper_buffer->pages);
    +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_heap(struct cma *cma, void *data)
    +{
    + struct cma_heap *cma_heap;
    + struct dma_heap_export_info exp_info;
    +
    + cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
    + if (!cma_heap)
    + return -ENOMEM;
    + cma_heap->cma = cma;
    +
    + exp_info.name = cma_get_name(cma);
    + exp_info.ops = &cma_heap_ops;
    + exp_info.priv = cma_heap;
    +
    + cma_heap->heap = dma_heap_add(&exp_info);
    + if (IS_ERR(cma_heap->heap)) {
    + int ret = PTR_ERR(cma_heap->heap);
    +
    + kfree(cma_heap);
    + return ret;
    + }
    +
    + return 0;
    +}
    +
    +static int add_cma_heaps(void)
    +{
    + cma_for_each_area(__add_cma_heap, NULL);
    + return 0;
    +}
    +device_initcall(add_cma_heaps);
    --
    2.17.1
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