dma-buf: Add dma-buf heaps framework

This framework allows a unified userspace interface for dma-buf
exporters, allowing userland to allocate specific types of memory
for use in dma-buf sharing.

Each heap is given its own device node, which a user can allocate
a dma-buf fd from using the DMA_HEAP_IOC_ALLOC.

This code is an evoluiton of the Android ION implementation,
and a big thanks is due to its authors/maintainers over time
for their effort:
  Rebecca Schultz Zavin, Colin Cross, Benjamin Gaignard,
  Laura Abbott, and many other contributors!

Cc: Laura Abbott <[email protected]>
Cc: Benjamin Gaignard <[email protected]>
Cc: Sumit Semwal <[email protected]>
Cc: Liam Mark <[email protected]>
Cc: Pratik Patel <[email protected]>
Cc: Brian Starkey <[email protected]>
Cc: Vincent Donnefort <[email protected]>
Cc: Sudipto Paul <[email protected]>
Cc: Andrew F. Davis <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Chenbo Feng <[email protected]>
Cc: Alistair Strachan <[email protected]>
Cc: Hridya Valsaraju <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: [email protected]
Reviewed-by: Benjamin Gaignard <[email protected]>
Reviewed-by: Brian Starkey <[email protected]>
Acked-by: Laura Abbott <[email protected]>
Tested-by: Ayan Kumar Halder <[email protected]>
Signed-off-by: Andrew F. Davis <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Signed-off-by: Sumit Semwal <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

1 files changed, 55 insertions, 0 deletions

diff --git a/include/uapi/linux/dma-heap.h b/include/uapi/linux/dma-heap.h
new file mode 100644
index 000000000000..6ce5cc68d238
--- /dev/null
+++ b/include/uapi/linux/dma-heap.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * DMABUF Heaps Userspace API
+ *
+ * Copyright (C) 2011 Google, Inc.
+ * Copyright (C) 2019 Linaro Ltd.
+ */
+#ifndef _UAPI_LINUX_DMABUF_POOL_H
+#define _UAPI_LINUX_DMABUF_POOL_H
+
+#include <linux/ioctl.h>
+#include <linux/types.h>
+
+/**
+ * DOC: DMABUF Heaps Userspace API
+ */
+
+/* Valid FD_FLAGS are O_CLOEXEC, O_RDONLY, O_WRONLY, O_RDWR */
+#define DMA_HEAP_VALID_FD_FLAGS (O_CLOEXEC | O_ACCMODE)
+
+/* Currently no heap flags */
+#define DMA_HEAP_VALID_HEAP_FLAGS (0)
+
+/**
+ * struct dma_heap_allocation_data - metadata passed from userspace for
+ *                                      allocations
+ * @len:		size of the allocation
+ * @fd:			will be populated with a fd which provdes the
+ *			handle to the allocated dma-buf
+ * @fd_flags:		file descriptor flags used when allocating
+ * @heap_flags:		flags passed to heap
+ *
+ * Provided by userspace as an argument to the ioctl
+ */
+struct dma_heap_allocation_data {
+	__u64 len;
+	__u32 fd;
+	__u32 fd_flags;
+	__u64 heap_flags;
+	__u32 reserved0;
+	__u32 reserved1;
+};
+
+#define DMA_HEAP_IOC_MAGIC		'H'
+
+/**
+ * DOC: DMA_HEAP_IOC_ALLOC - allocate memory from pool
+ *
+ * Takes an dma_heap_allocation_data struct and returns it with the fd field
+ * populated with the dmabuf handle of the allocation.
+ */
+#define DMA_HEAP_IOC_ALLOC	_IOWR(DMA_HEAP_IOC_MAGIC, 0, \
+				      struct dma_heap_allocation_data)
+
+#endif /* _UAPI_LINUX_DMABUF_POOL_H */