--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/device.h>
+#include <linux/dma-buf.h>
+#include <linux/err.h>
+#include <linux/highmem.h>
+#include <linux/idr.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <uapi/linux/dma-heap.h>
+
+#include "heap-helpers.h"
+
+void init_heap_helper_buffer(struct heap_helper_buffer *buffer,
+ void (*free)(struct heap_helper_buffer *))
+{
+ buffer->priv_virt = NULL;
+ mutex_init(&buffer->lock);
+ buffer->vmap_cnt = 0;
+ buffer->vaddr = NULL;
+ buffer->pagecount = 0;
+ buffer->pages = NULL;
+ INIT_LIST_HEAD(&buffer->attachments);
+ buffer->free = free;
+}
+
+struct dma_buf *heap_helper_export_dmabuf(struct heap_helper_buffer *buffer,
+ int fd_flags)
+{
+ DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+
+ exp_info.ops = &heap_helper_ops;
+ exp_info.size = buffer->size;
+ exp_info.flags = fd_flags;
+ exp_info.priv = buffer;
+
+ return dma_buf_export(&exp_info);
+}
+
+static void *dma_heap_map_kernel(struct heap_helper_buffer *buffer)
+{
+ void *vaddr;
+
+ vaddr = vmap(buffer->pages, buffer->pagecount, VM_MAP, PAGE_KERNEL);
+ if (!vaddr)
+ return ERR_PTR(-ENOMEM);
+
+ return vaddr;
+}
+
+static void dma_heap_buffer_destroy(struct heap_helper_buffer *buffer)
+{
+ if (buffer->vmap_cnt > 0) {
+ WARN(1, "%s: buffer still mapped in the kernel\n", __func__);
+ vunmap(buffer->vaddr);
+ }
+
+ buffer->free(buffer);
+}
+
+static void *dma_heap_buffer_vmap_get(struct heap_helper_buffer *buffer)
+{
+ void *vaddr;
+
+ if (buffer->vmap_cnt) {
+ buffer->vmap_cnt++;
+ return buffer->vaddr;
+ }
+ vaddr = dma_heap_map_kernel(buffer);
+ if (IS_ERR(vaddr))
+ return vaddr;
+ buffer->vaddr = vaddr;
+ buffer->vmap_cnt++;
+ return vaddr;
+}
+
+static void dma_heap_buffer_vmap_put(struct heap_helper_buffer *buffer)
+{
+ if (!--buffer->vmap_cnt) {
+ vunmap(buffer->vaddr);
+ buffer->vaddr = NULL;
+ }
+}
+
+struct dma_heaps_attachment {
+ struct device *dev;
+ struct sg_table table;
+ struct list_head list;
+};
+
+static int dma_heap_attach(struct dma_buf *dmabuf,
+ struct dma_buf_attachment *attachment)
+{
+ struct dma_heaps_attachment *a;
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+ int ret;
+
+ a = kzalloc(sizeof(*a), GFP_KERNEL);
+ if (!a)
+ return -ENOMEM;
+
+ ret = sg_alloc_table_from_pages(&a->table, buffer->pages,
+ buffer->pagecount, 0,
+ buffer->pagecount << PAGE_SHIFT,
+ GFP_KERNEL);
+ if (ret) {
+ kfree(a);
+ return ret;
+ }
+
+ a->dev = attachment->dev;
+ INIT_LIST_HEAD(&a->list);
+
+ attachment->priv = a;
+
+ mutex_lock(&buffer->lock);
+ list_add(&a->list, &buffer->attachments);
+ mutex_unlock(&buffer->lock);
+
+ return 0;
+}
+
+static void dma_heap_detach(struct dma_buf *dmabuf,
+ struct dma_buf_attachment *attachment)
+{
+ struct dma_heaps_attachment *a = attachment->priv;
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+
+ mutex_lock(&buffer->lock);
+ list_del(&a->list);
+ mutex_unlock(&buffer->lock);
+
+ sg_free_table(&a->table);
+ kfree(a);
+}
+
+static
+struct sg_table *dma_heap_map_dma_buf(struct dma_buf_attachment *attachment,
+ enum dma_data_direction direction)
+{
+ struct dma_heaps_attachment *a = attachment->priv;
+ struct sg_table *table;
+
+ table = &a->table;
+
+ if (!dma_map_sg(attachment->dev, table->sgl, table->nents,
+ direction))
+ table = ERR_PTR(-ENOMEM);
+ return table;
+}
+
+static void dma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
+ struct sg_table *table,
+ enum dma_data_direction direction)
+{
+ dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction);
+}
+
+static vm_fault_t dma_heap_vm_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct heap_helper_buffer *buffer = vma->vm_private_data;
+
+ if (vmf->pgoff > buffer->pagecount)
+ return VM_FAULT_SIGBUS;
+
+ vmf->page = buffer->pages[vmf->pgoff];
+ get_page(vmf->page);
+
+ return 0;
+}
+
+static const struct vm_operations_struct dma_heap_vm_ops = {
+ .fault = dma_heap_vm_fault,
+};
+
+static int dma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
+{
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+
+ if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
+ return -EINVAL;
+
+ vma->vm_ops = &dma_heap_vm_ops;
+ vma->vm_private_data = buffer;
+
+ return 0;
+}
+
+static void dma_heap_dma_buf_release(struct dma_buf *dmabuf)
+{
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+
+ dma_heap_buffer_destroy(buffer);
+}
+
+static int dma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
+ enum dma_data_direction direction)
+{
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+ struct dma_heaps_attachment *a;
+ int ret = 0;
+
+ mutex_lock(&buffer->lock);
+
+ if (buffer->vmap_cnt)
+ invalidate_kernel_vmap_range(buffer->vaddr, buffer->size);
+
+ list_for_each_entry(a, &buffer->attachments, list) {
+ dma_sync_sg_for_cpu(a->dev, a->table.sgl, a->table.nents,
+ direction);
+ }
+ mutex_unlock(&buffer->lock);
+
+ return ret;
+}
+
+static int dma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
+ enum dma_data_direction direction)
+{
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+ struct dma_heaps_attachment *a;
+
+ mutex_lock(&buffer->lock);
+
+ if (buffer->vmap_cnt)
+ flush_kernel_vmap_range(buffer->vaddr, buffer->size);
+
+ list_for_each_entry(a, &buffer->attachments, list) {
+ dma_sync_sg_for_device(a->dev, a->table.sgl, a->table.nents,
+ direction);
+ }
+ mutex_unlock(&buffer->lock);
+
+ return 0;
+}
+
+static void *dma_heap_dma_buf_vmap(struct dma_buf *dmabuf)
+{
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+ void *vaddr;
+
+ mutex_lock(&buffer->lock);
+ vaddr = dma_heap_buffer_vmap_get(buffer);
+ mutex_unlock(&buffer->lock);
+
+ return vaddr;
+}
+
+static void dma_heap_dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
+{
+ struct heap_helper_buffer *buffer = dmabuf->priv;
+
+ mutex_lock(&buffer->lock);
+ dma_heap_buffer_vmap_put(buffer);
+ mutex_unlock(&buffer->lock);
+}
+
+const struct dma_buf_ops heap_helper_ops = {
+ .map_dma_buf = dma_heap_map_dma_buf,
+ .unmap_dma_buf = dma_heap_unmap_dma_buf,
+ .mmap = dma_heap_mmap,
+ .release = dma_heap_dma_buf_release,
+ .attach = dma_heap_attach,
+ .detach = dma_heap_detach,
+ .begin_cpu_access = dma_heap_dma_buf_begin_cpu_access,
+ .end_cpu_access = dma_heap_dma_buf_end_cpu_access,
+ .vmap = dma_heap_dma_buf_vmap,
+ .vunmap = dma_heap_dma_buf_vunmap,
+};
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * DMABUF Heaps helper code
+ *
+ * Copyright (C) 2011 Google, Inc.
+ * Copyright (C) 2019 Linaro Ltd.
+ */
+
+#ifndef _HEAP_HELPERS_H
+#define _HEAP_HELPERS_H
+
+#include <linux/dma-heap.h>
+#include <linux/list.h>
+
+/**
+ * struct heap_helper_buffer - helper buffer metadata
+ * @heap: back pointer to the heap the buffer came from
+ * @dmabuf: backing dma-buf for this buffer
+ * @size: size of the buffer
+ * @priv_virt pointer to heap specific private value
+ * @lock mutext to protect the data in this structure
+ * @vmap_cnt count of vmap references on the buffer
+ * @vaddr vmap'ed virtual address
+ * @pagecount number of pages in the buffer
+ * @pages list of page pointers
+ * @attachments list of device attachments
+ *
+ * @free heap callback to free the buffer
+ */
+struct heap_helper_buffer {
+ struct dma_heap *heap;
+ struct dma_buf *dmabuf;
+ size_t size;
+
+ void *priv_virt;
+ struct mutex lock;
+ int vmap_cnt;
+ void *vaddr;
+ pgoff_t pagecount;
+ struct page **pages;
+ struct list_head attachments;
+
+ void (*free)(struct heap_helper_buffer *buffer);
+};
+
+void init_heap_helper_buffer(struct heap_helper_buffer *buffer,
+ void (*free)(struct heap_helper_buffer *));
+
+struct dma_buf *heap_helper_export_dmabuf(struct heap_helper_buffer *buffer,
+ int fd_flags);
+
+extern const struct dma_buf_ops heap_helper_ops;
+#endif /* _HEAP_HELPERS_H */
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