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    SubjectRe: [RFC][PATCH 4/5 v2] dma-buf: heaps: Add CMA heap to dmabuf heapss
    Le mar. 5 mars 2019 à 21:54, John Stultz <john.stultz@linaro.org> a écrit :
    >
    > 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)

    Even if I had write this macro years ago, now I would prefer to have a
    static inline function
    to be able to check the types.

    with that:
    Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

    > +
    > +
    > +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
    >


    --
    Benjamin Gaignard

    Graphic Study Group

    Linaro.org │ Open source software for ARM SoCs

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