summaryrefslogtreecommitdiff
path: root/include/linux/dma-buf-map.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/dma-buf-map.h')
-rw-r--r--include/linux/dma-buf-map.h266
1 files changed, 0 insertions, 266 deletions
diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h
deleted file mode 100644
index 278d489e4bdd..000000000000
--- a/include/linux/dma-buf-map.h
+++ /dev/null
@@ -1,266 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Pointer to dma-buf-mapped memory, plus helpers.
- */
-
-#ifndef __DMA_BUF_MAP_H__
-#define __DMA_BUF_MAP_H__
-
-#include <linux/io.h>
-#include <linux/string.h>
-
-/**
- * DOC: overview
- *
- * Calling dma-buf's vmap operation returns a pointer to the buffer's memory.
- * Depending on the location of the buffer, users may have to access it with
- * I/O operations or memory load/store operations. For example, copying to
- * system memory could be done with memcpy(), copying to I/O memory would be
- * done with memcpy_toio().
- *
- * .. code-block:: c
- *
- * void *vaddr = ...; // pointer to system memory
- * memcpy(vaddr, src, len);
- *
- * void *vaddr_iomem = ...; // pointer to I/O memory
- * memcpy_toio(vaddr, _iomem, src, len);
- *
- * When using dma-buf's vmap operation, the returned pointer is encoded as
- * :c:type:`struct dma_buf_map <dma_buf_map>`.
- * :c:type:`struct dma_buf_map <dma_buf_map>` stores the buffer's address in
- * system or I/O memory and a flag that signals the required method of
- * accessing the buffer. Use the returned instance and the helper functions
- * to access the buffer's memory in the correct way.
- *
- * The type :c:type:`struct dma_buf_map <dma_buf_map>` and its helpers are
- * actually independent from the dma-buf infrastructure. When sharing buffers
- * among devices, drivers have to know the location of the memory to access
- * the buffers in a safe way. :c:type:`struct dma_buf_map <dma_buf_map>`
- * solves this problem for dma-buf and its users. If other drivers or
- * sub-systems require similar functionality, the type could be generalized
- * and moved to a more prominent header file.
- *
- * Open-coding access to :c:type:`struct dma_buf_map <dma_buf_map>` is
- * considered bad style. Rather then accessing its fields directly, use one
- * of the provided helper functions, or implement your own. For example,
- * instances of :c:type:`struct dma_buf_map <dma_buf_map>` can be initialized
- * statically with DMA_BUF_MAP_INIT_VADDR(), or at runtime with
- * dma_buf_map_set_vaddr(). These helpers will set an address in system memory.
- *
- * .. code-block:: c
- *
- * struct dma_buf_map map = DMA_BUF_MAP_INIT_VADDR(0xdeadbeaf);
- *
- * dma_buf_map_set_vaddr(&map. 0xdeadbeaf);
- *
- * To set an address in I/O memory, use dma_buf_map_set_vaddr_iomem().
- *
- * .. code-block:: c
- *
- * dma_buf_map_set_vaddr_iomem(&map. 0xdeadbeaf);
- *
- * Instances of struct dma_buf_map do not have to be cleaned up, but
- * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings
- * always refer to system memory.
- *
- * .. code-block:: c
- *
- * dma_buf_map_clear(&map);
- *
- * Test if a mapping is valid with either dma_buf_map_is_set() or
- * dma_buf_map_is_null().
- *
- * .. code-block:: c
- *
- * if (dma_buf_map_is_set(&map) != dma_buf_map_is_null(&map))
- * // always true
- *
- * Instances of :c:type:`struct dma_buf_map <dma_buf_map>` can be compared
- * for equality with dma_buf_map_is_equal(). Mappings the point to different
- * memory spaces, system or I/O, are never equal. That's even true if both
- * spaces are located in the same address space, both mappings contain the
- * same address value, or both mappings refer to NULL.
- *
- * .. code-block:: c
- *
- * struct dma_buf_map sys_map; // refers to system memory
- * struct dma_buf_map io_map; // refers to I/O memory
- *
- * if (dma_buf_map_is_equal(&sys_map, &io_map))
- * // always false
- *
- * A set up instance of struct dma_buf_map can be used to access or manipulate
- * the buffer memory. Depending on the location of the memory, the provided
- * helpers will pick the correct operations. Data can be copied into the memory
- * with dma_buf_map_memcpy_to(). The address can be manipulated with
- * dma_buf_map_incr().
- *
- * .. code-block:: c
- *
- * const void *src = ...; // source buffer
- * size_t len = ...; // length of src
- *
- * dma_buf_map_memcpy_to(&map, src, len);
- * dma_buf_map_incr(&map, len); // go to first byte after the memcpy
- */
-
-/**
- * struct dma_buf_map - Pointer to vmap'ed dma-buf memory.
- * @vaddr_iomem: The buffer's address if in I/O memory
- * @vaddr: The buffer's address if in system memory
- * @is_iomem: True if the dma-buf memory is located in I/O
- * memory, or false otherwise.
- */
-struct dma_buf_map {
- union {
- void __iomem *vaddr_iomem;
- void *vaddr;
- };
- bool is_iomem;
-};
-
-/**
- * DMA_BUF_MAP_INIT_VADDR - Initializes struct dma_buf_map to an address in system memory
- * @vaddr_: A system-memory address
- */
-#define DMA_BUF_MAP_INIT_VADDR(vaddr_) \
- { \
- .vaddr = (vaddr_), \
- .is_iomem = false, \
- }
-
-/**
- * dma_buf_map_set_vaddr - Sets a dma-buf mapping structure to an address in system memory
- * @map: The dma-buf mapping structure
- * @vaddr: A system-memory address
- *
- * Sets the address and clears the I/O-memory flag.
- */
-static inline void dma_buf_map_set_vaddr(struct dma_buf_map *map, void *vaddr)
-{
- map->vaddr = vaddr;
- map->is_iomem = false;
-}
-
-/**
- * dma_buf_map_set_vaddr_iomem - Sets a dma-buf mapping structure to an address in I/O memory
- * @map: The dma-buf mapping structure
- * @vaddr_iomem: An I/O-memory address
- *
- * Sets the address and the I/O-memory flag.
- */
-static inline void dma_buf_map_set_vaddr_iomem(struct dma_buf_map *map,
- void __iomem *vaddr_iomem)
-{
- map->vaddr_iomem = vaddr_iomem;
- map->is_iomem = true;
-}
-
-/**
- * dma_buf_map_is_equal - Compares two dma-buf mapping structures for equality
- * @lhs: The dma-buf mapping structure
- * @rhs: A dma-buf mapping structure to compare with
- *
- * Two dma-buf mapping structures are equal if they both refer to the same type of memory
- * and to the same address within that memory.
- *
- * Returns:
- * True is both structures are equal, or false otherwise.
- */
-static inline bool dma_buf_map_is_equal(const struct dma_buf_map *lhs,
- const struct dma_buf_map *rhs)
-{
- if (lhs->is_iomem != rhs->is_iomem)
- return false;
- else if (lhs->is_iomem)
- return lhs->vaddr_iomem == rhs->vaddr_iomem;
- else
- return lhs->vaddr == rhs->vaddr;
-}
-
-/**
- * dma_buf_map_is_null - Tests for a dma-buf mapping to be NULL
- * @map: The dma-buf mapping structure
- *
- * Depending on the state of struct dma_buf_map.is_iomem, tests if the
- * mapping is NULL.
- *
- * Returns:
- * True if the mapping is NULL, or false otherwise.
- */
-static inline bool dma_buf_map_is_null(const struct dma_buf_map *map)
-{
- if (map->is_iomem)
- return !map->vaddr_iomem;
- return !map->vaddr;
-}
-
-/**
- * dma_buf_map_is_set - Tests is the dma-buf mapping has been set
- * @map: The dma-buf mapping structure
- *
- * Depending on the state of struct dma_buf_map.is_iomem, tests if the
- * mapping has been set.
- *
- * Returns:
- * True if the mapping is been set, or false otherwise.
- */
-static inline bool dma_buf_map_is_set(const struct dma_buf_map *map)
-{
- return !dma_buf_map_is_null(map);
-}
-
-/**
- * dma_buf_map_clear - Clears a dma-buf mapping structure
- * @map: The dma-buf mapping structure
- *
- * Clears all fields to zero; including struct dma_buf_map.is_iomem. So
- * mapping structures that were set to point to I/O memory are reset for
- * system memory. Pointers are cleared to NULL. This is the default.
- */
-static inline void dma_buf_map_clear(struct dma_buf_map *map)
-{
- if (map->is_iomem) {
- map->vaddr_iomem = NULL;
- map->is_iomem = false;
- } else {
- map->vaddr = NULL;
- }
-}
-
-/**
- * dma_buf_map_memcpy_to - Memcpy into dma-buf mapping
- * @dst: The dma-buf mapping structure
- * @src: The source buffer
- * @len: The number of byte in src
- *
- * Copies data into a dma-buf mapping. The source buffer is in system
- * memory. Depending on the buffer's location, the helper picks the correct
- * method of accessing the memory.
- */
-static inline void dma_buf_map_memcpy_to(struct dma_buf_map *dst, const void *src, size_t len)
-{
- if (dst->is_iomem)
- memcpy_toio(dst->vaddr_iomem, src, len);
- else
- memcpy(dst->vaddr, src, len);
-}
-
-/**
- * dma_buf_map_incr - Increments the address stored in a dma-buf mapping
- * @map: The dma-buf mapping structure
- * @incr: The number of bytes to increment
- *
- * Increments the address stored in a dma-buf mapping. Depending on the
- * buffer's location, the correct value will be updated.
- */
-static inline void dma_buf_map_incr(struct dma_buf_map *map, size_t incr)
-{
- if (map->is_iomem)
- map->vaddr_iomem += incr;
- else
- map->vaddr += incr;
-}
-
-#endif /* __DMA_BUF_MAP_H__ */