[EARLY RFC][PATCH 4/4] dma-buf: pools: Add CMA pool to dmabuf pools

[John Stultz <john.stultz@linaro.org>]

This adds a CMA pool, which allows userspace to allocate
a dma-buf of contiguous memory out of a CMA region.

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: 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>
---
 drivers/dma-buf/pools/Kconfig    |   8 +++
 drivers/dma-buf/pools/Makefile   |   1 +
 drivers/dma-buf/pools/cma_pool.c | 143 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 152 insertions(+)
 create mode 100644 drivers/dma-buf/pools/cma_pool.c

diff --git a/drivers/dma-buf/pools/Kconfig b/drivers/dma-buf/pools/Kconfig
index 787b2a6..e984304 100644
--- a/drivers/dma-buf/pools/Kconfig
+++ b/drivers/dma-buf/pools/Kconfig
@@ -15,3 +15,11 @@ config DMABUF_POOLS_SYSTEM
 	help
 	  Choose this option to enable the system dmabuf pool. The system pool
 	  is backed by pages from the buddy allocator. If in doubt, say Y.
+
+config DMABUF_POOLS_CMA
+	bool "DMA-BUF CMA Pool"
+	depends on DMABUF_POOLS && DMA_CMA
+	help
+	  Choose this option to enable dma-buf CMA pools. This pool 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/pools/Makefile b/drivers/dma-buf/pools/Makefile
index 2ccf2a1..ac8aa28 100644
--- a/drivers/dma-buf/pools/Makefile
+++ b/drivers/dma-buf/pools/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_DMABUF_POOLS)		+= dmabuf-pools.o pool-ioctl.o pool-helpers.o page_pool.o
 obj-$(CONFIG_DMABUF_POOLS_SYSTEM)	+= system_pool.o
+obj-$(CONFIG_DMABUF_POOLS_CMA)		+= cma_pool.o
diff --git a/drivers/dma-buf/pools/cma_pool.c b/drivers/dma-buf/pools/cma_pool.c
new file mode 100644
index 0000000..0bd783f
--- /dev/null
+++ b/drivers/dma-buf/pools/cma_pool.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * drivers/dma-buf/pools/cma_pool.c
+ *
+ * Copyright (C) 2012, 2019 Linaro Ltd.
+ * Author: <benjamin.gaignard@linaro.org> for ST-Ericsson.
+ */
+
+#include <linux/device.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 "dmabuf-pools.h"
+
+struct cma_pool {
+	struct dmabuf_pool pool;
+	struct cma *cma;
+};
+
+#define to_cma_pool(x) container_of(x, struct cma_pool, pool)
+
+/* dmabuf pool CMA operations functions */
+static int cma_pool_allocate(struct dmabuf_pool *pool,
+			     struct dmabuf_pool_buffer *buffer,
+			     unsigned long len,
+			     unsigned long flags)
+{
+	struct cma_pool *cma_pool = to_cma_pool(pool);
+	struct sg_table *table;
+	struct page *pages;
+	unsigned long size = PAGE_ALIGN(len);
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	unsigned long align = get_order(size);
+	int ret;
+
+	if (align > CONFIG_CMA_ALIGNMENT)
+		align = CONFIG_CMA_ALIGNMENT;
+
+	pages = cma_alloc(cma_pool->cma, nr_pages, align, false);
+	if (!pages)
+		return -ENOMEM;
+
+	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 err;
+
+	ret = sg_alloc_table(table, 1, GFP_KERNEL);
+	if (ret)
+		goto free_mem;
+
+	sg_set_page(table->sgl, pages, size, 0);
+
+	buffer->priv_virt = pages;
+	buffer->sg_table = table;
+	return 0;
+
+free_mem:
+	kfree(table);
+err:
+	cma_release(cma_pool->cma, pages, nr_pages);
+	return -ENOMEM;
+}
+
+static void cma_pool_free(struct dmabuf_pool_buffer *buffer)
+{
+	struct cma_pool *cma_pool = to_cma_pool(buffer->pool);
+	struct page *pages = buffer->priv_virt;
+	unsigned long nr_pages = PAGE_ALIGN(buffer->size) >> PAGE_SHIFT;
+
+	/* release memory */
+	cma_release(cma_pool->cma, pages, nr_pages);
+	/* release sg table */
+	sg_free_table(buffer->sg_table);
+	kfree(buffer->sg_table);
+}
+
+static struct dmabuf_pool_ops cma_pool_ops = {
+	.allocate = cma_pool_allocate,
+	.free = cma_pool_free,
+	.map_user = dmabuf_pool_map_user,
+	.map_kernel = dmabuf_pool_map_kernel,
+	.unmap_kernel = dmabuf_pool_unmap_kernel,
+};
+
+static struct dmabuf_pool *__cma_pool_create(struct cma *cma)
+{
+	struct cma_pool *cma_pool;
+
+	cma_pool = kzalloc(sizeof(*cma_pool), GFP_KERNEL);
+
+	if (!cma_pool)
+		return ERR_PTR(-ENOMEM);
+
+	cma_pool->pool.ops = &cma_pool_ops;
+	/*
+	 * get device from private pools data, later it will be
+	 * used to make the link with reserved CMA memory
+	 */
+	cma_pool->cma = cma;
+	return &cma_pool->pool;
+}
+
+static int __add_cma_pools(struct cma *cma, void *data)
+{
+	struct dmabuf_pool *pool;
+
+	pool = __cma_pool_create(cma);
+	if (IS_ERR(pool))
+		return PTR_ERR(pool);
+
+	pool->name = cma_get_name(cma);
+
+	dmabuf_pool_add(pool);
+
+	return 0;
+}
+
+static int add_cma_pools(void)
+{
+	cma_for_each_area(__add_cma_pools, NULL);
+	return 0;
+}
+device_initcall(add_cma_pools);
-- 
2.7.4

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