[PATCH 2/3] dma-buf: heaps: add chunk heap to dmabuf heaps

[Hyesoo Yu]

This patch adds support for a chunk heap that allows for buffers
that are made up of a list of fixed size chunks taken from a CMA.
Chunk sizes are configuratd when the heaps are created.

Signed-off-by: Hyesoo Yu <hyesoo.yu@xxxxxxxxxxx>
---
 drivers/dma-buf/heaps/Kconfig      |   9 ++
 drivers/dma-buf/heaps/Makefile     |   1 +
 drivers/dma-buf/heaps/chunk_heap.c | 222 +++++++++++++++++++++++++++++++++++++
 3 files changed, 232 insertions(+)
 create mode 100644 drivers/dma-buf/heaps/chunk_heap.c

diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index a5eef06..98552fa 100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -12,3 +12,12 @@ config DMABUF_HEAPS_CMA
 	  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.
+
+config DMABUF_HEAPS_CHUNK
+	tristate "DMA-BUF CHUNK Heap"
+	depends on DMABUF_HEAPS && DMA_CMA
+	help
+	  Choose this option to enable dma-buf CHUNK heap. This heap is backed
+	  by the Contiguous Memory Allocator (CMA) and allocate the buffers that
+	  are made up to a list of fixed size chunks tasken from CMA. Chunk sizes
+	  are configurated when the heaps are created.
diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
index 6e54cde..3b2a0986 100644
--- a/drivers/dma-buf/heaps/Makefile
+++ b/drivers/dma-buf/heaps/Makefile
@@ -2,3 +2,4 @@
 obj-y					+= heap-helpers.o
 obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)	+= system_heap.o
 obj-$(CONFIG_DMABUF_HEAPS_CMA)		+= cma_heap.o
+obj-$(CONFIG_DMABUF_HEAPS_CHUNK)	+= chunk_heap.o
diff --git a/drivers/dma-buf/heaps/chunk_heap.c b/drivers/dma-buf/heaps/chunk_heap.c
new file mode 100644
index 0000000..1eefaec
--- /dev/null
+++ b/drivers/dma-buf/heaps/chunk_heap.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ION Memory Allocator chunk heap exporter
+ *
+ * Copyright (c) 2020 Samsung Electronics Co., Ltd.
+ * Author: <hyesoo.yu@xxxxxxxxxxx> for Samsung Electronics.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/cma.h>
+#include <linux/device.h>
+#include <linux/dma-buf.h>
+#include <linux/dma-heap.h>
+#include <linux/dma-contiguous.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/scatterlist.h>
+#include <linux/sched/signal.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/of.h>
+
+#include "heap-helpers.h"
+
+struct chunk_heap {
+	struct dma_heap *heap;
+	phys_addr_t base;
+	phys_addr_t size;
+	atomic_t cur_pageblock_idx;
+	unsigned int max_num_pageblocks;
+	unsigned int order;
+};
+
+static void chunk_heap_free(struct heap_helper_buffer *buffer)
+{
+	struct chunk_heap *chunk_heap = dma_heap_get_drvdata(buffer->heap);
+	pgoff_t pg;
+
+	for (pg = 0; pg < buffer->pagecount; pg++)
+		__free_pages(buffer->pages[pg], chunk_heap->order);
+	kvfree(buffer->pages);
+	kfree(buffer);
+}
+
+static inline unsigned long chunk_get_next_pfn(struct chunk_heap *chunk_heap)
+{
+	unsigned long i = atomic_inc_return(&chunk_heap->cur_pageblock_idx) %
+		chunk_heap->max_num_pageblocks;
+
+	return PHYS_PFN(chunk_heap->base) + i * pageblock_nr_pages;
+}
+
+static int chunk_alloc_pages(struct chunk_heap *chunk_heap, struct page **pages,
+			     unsigned int order, unsigned int count)
+{
+	unsigned long base;
+	unsigned int i = 0, nr_block = 0, nr_elem, ret;
+
+	while (count) {
+		/*
+		 * If the number of scanned page block is the same as max block,
+		 * the tries of allocation fails.
+		 */
+		if (nr_block++ == chunk_heap->max_num_pageblocks) {
+			ret = -ENOMEM;
+			goto err_bulk;
+		}
+		base = chunk_get_next_pfn(chunk_heap);
+		nr_elem = min_t(unsigned int, count, pageblock_nr_pages >> order);
+		ret = alloc_pages_bulk(base, base + pageblock_nr_pages, MIGRATE_CMA,
+				       GFP_KERNEL, order, nr_elem, pages + i);
+		if (ret < 0)
+			goto err_bulk;
+
+		i += ret;
+		count -= ret;
+	}
+
+	return 0;
+
+err_bulk:
+	while (i-- > 0)
+		__free_pages(pages[i], order);
+
+	return ret;
+}
+
+static int chunk_heap_allocate(struct dma_heap *heap, unsigned long len,
+			     unsigned long fd_flags, unsigned long heap_flags)
+{
+
+	struct chunk_heap *chunk_heap = dma_heap_get_drvdata(heap);
+	struct heap_helper_buffer *helper_buffer;
+	struct dma_buf *dmabuf;
+	unsigned int count = DIV_ROUND_UP(len, PAGE_SIZE << chunk_heap->order);
+	int ret = -ENOMEM;
+
+	helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL);
+	if (!helper_buffer)
+		return ret;
+
+	init_heap_helper_buffer(helper_buffer, chunk_heap_free);
+
+	helper_buffer->heap = heap;
+	helper_buffer->size = ALIGN(len, PAGE_SIZE << chunk_heap->order);
+	helper_buffer->pagecount = count;
+	helper_buffer->pages = kvmalloc_array(helper_buffer->pagecount,
+					      sizeof(*helper_buffer->pages), GFP_KERNEL);
+	if (!helper_buffer->pages)
+		goto err0;
+
+	ret = chunk_alloc_pages(chunk_heap, helper_buffer->pages,
+				chunk_heap->order, helper_buffer->pagecount);
+	if (ret < 0)
+		goto err1;
+
+	dmabuf = heap_helper_export_dmabuf(helper_buffer, fd_flags);
+	if (IS_ERR(dmabuf)) {
+		ret = PTR_ERR(dmabuf);
+		goto err2;
+	}
+
+	helper_buffer->dmabuf = dmabuf;
+
+	ret = dma_buf_fd(dmabuf, fd_flags);
+	if (ret < 0) {
+		dma_buf_put(dmabuf);
+		return ret;
+	}
+
+	return ret;
+
+err2:
+	while (count-- > 0)
+		__free_pages(helper_buffer->pages[count], chunk_heap->order);
+err1:
+	kvfree(helper_buffer->pages);
+err0:
+	kfree(helper_buffer);
+
+	return ret;
+}
+
+static void rmem_remove_callback(void *p)
+{
+	of_reserved_mem_device_release((struct device *)p);
+}
+
+static const struct dma_heap_ops chunk_heap_ops = {
+	.allocate = chunk_heap_allocate,
+};
+
+static int chunk_heap_probe(struct platform_device *pdev)
+{
+	struct chunk_heap *chunk_heap;
+	struct reserved_mem *rmem;
+	struct device_node *rmem_np;
+	struct dma_heap_export_info exp_info;
+	unsigned int alignment;
+	int ret;
+
+	ret = of_reserved_mem_device_init(&pdev->dev);
+	if (ret || !pdev->dev.cma_area) {
+		dev_err(&pdev->dev, "The CMA reserved area is not assigned (ret %d)", ret);
+		return -EINVAL;
+	}
+
+	ret = devm_add_action(&pdev->dev, rmem_remove_callback, &pdev->dev);
+	if (ret) {
+		of_reserved_mem_device_release(&pdev->dev);
+		return ret;
+	}
+
+	rmem_np = of_parse_phandle(pdev->dev.of_node, "memory-region", 0);
+	rmem = of_reserved_mem_lookup(rmem_np);
+
+	chunk_heap = devm_kzalloc(&pdev->dev, sizeof(*chunk_heap), GFP_KERNEL);
+	if (!chunk_heap)
+		return -ENOMEM;
+
+	chunk_heap->base = rmem->base;
+	chunk_heap->size = rmem->size;
+	chunk_heap->max_num_pageblocks = rmem->size >> (pageblock_order + PAGE_SHIFT);
+
+	of_property_read_u32(pdev->dev.of_node, "alignment", &alignment);
+	chunk_heap->order = get_order(alignment);
+
+	exp_info.name = rmem->name;
+	exp_info.ops = &chunk_heap_ops;
+	exp_info.priv = chunk_heap;
+
+	chunk_heap->heap = dma_heap_add(&exp_info);
+	if (IS_ERR(chunk_heap->heap))
+		return PTR_ERR(chunk_heap->heap);
+
+	return 0;
+}
+
+static const struct of_device_id chunk_heap_of_match[] = {
+	{ .compatible = "dma_heap,chunk", },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, chunk_heap_of_match);
+
+static struct platform_driver chunk_heap_driver = {
+	.driver		= {
+		.name	= "chunk_heap",
+		.of_match_table = chunk_heap_of_match,
+	},
+	.probe		= chunk_heap_probe,
+};
+
+static int __init chunk_heap_init(void)
+{
+	return platform_driver_register(&chunk_heap_driver);
+}
+module_init(chunk_heap_init);
+MODULE_DESCRIPTION("DMA-BUF Chunk Heap");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4