diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/dma-buf-map.h | 193 | ||||
| -rw-r--r-- | include/linux/dma-buf.h | 14 | ||||
| -rw-r--r-- | include/linux/platform_data/shmob_drm.h | 2 |
3 files changed, 201 insertions, 8 deletions
diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h new file mode 100644 index 000000000000..fd1aba545fdf --- /dev/null +++ b/include/linux/dma-buf-map.h @@ -0,0 +1,193 @@ +/* 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> + +/** + * 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. + * + * 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); + * + * 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 + * + * 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. + * + * 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. + */ + +/** + * 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_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; + } +} + +#endif /* __DMA_BUF_MAP_H__ */ diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 957b398d30e5..03875eaed51a 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -13,6 +13,7 @@ #ifndef __DMA_BUF_H__ #define __DMA_BUF_H__ +#include <linux/dma-buf-map.h> #include <linux/file.h> #include <linux/err.h> #include <linux/scatterlist.h> @@ -145,7 +146,8 @@ struct dma_buf_ops { * * A &sg_table scatter list of or the backing storage of the DMA buffer, * already mapped into the device address space of the &device attached - * with the provided &dma_buf_attachment. + * with the provided &dma_buf_attachment. The addresses and lengths in + * the scatter list are PAGE_SIZE aligned. * * On failure, returns a negative error value wrapped into a pointer. * May also return -EINTR when a signal was received while being @@ -265,8 +267,8 @@ struct dma_buf_ops { */ int (*mmap)(struct dma_buf *, struct vm_area_struct *vma); - void *(*vmap)(struct dma_buf *); - void (*vunmap)(struct dma_buf *, void *vaddr); + int (*vmap)(struct dma_buf *dmabuf, struct dma_buf_map *map); + void (*vunmap)(struct dma_buf *dmabuf, struct dma_buf_map *map); }; /** @@ -309,7 +311,7 @@ struct dma_buf { const struct dma_buf_ops *ops; struct mutex lock; unsigned vmapping_counter; - void *vmap_ptr; + struct dma_buf_map vmap_ptr; const char *exp_name; const char *name; spinlock_t name_lock; @@ -502,6 +504,6 @@ int dma_buf_end_cpu_access(struct dma_buf *dma_buf, int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, unsigned long); -void *dma_buf_vmap(struct dma_buf *); -void dma_buf_vunmap(struct dma_buf *, void *vaddr); +int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map); +void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map); #endif /* __DMA_BUF_H__ */ diff --git a/include/linux/platform_data/shmob_drm.h b/include/linux/platform_data/shmob_drm.h index fe815d7d9f58..d661399b217d 100644 --- a/include/linux/platform_data/shmob_drm.h +++ b/include/linux/platform_data/shmob_drm.h @@ -10,8 +10,6 @@ #ifndef __SHMOB_DRM_H__ #define __SHMOB_DRM_H__ -#include <linux/kernel.h> - #include <drm/drm_mode.h> enum shmob_drm_clk_source { |