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Diffstat (limited to 'include/linux/iosys-map.h')
| -rw-r--r-- | include/linux/iosys-map.h | 516 |
1 files changed, 516 insertions, 0 deletions
diff --git a/include/linux/iosys-map.h b/include/linux/iosys-map.h new file mode 100644 index 000000000000..cb71aa616bd3 --- /dev/null +++ b/include/linux/iosys-map.h @@ -0,0 +1,516 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Pointer abstraction for IO/system memory + */ + +#ifndef __IOSYS_MAP_H__ +#define __IOSYS_MAP_H__ + +#include <linux/compiler_types.h> +#include <linux/io.h> +#include <linux/string.h> + +/** + * DOC: overview + * + * When accessing a memory region, depending on its location, 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); + * + * The user of such pointer may not have information about the mapping of that + * region or may want to have a single code path to handle operations on that + * buffer, regardless if it's located in system or IO memory. The type + * :c:type:`struct iosys_map <iosys_map>` and its helpers abstract that so the + * buffer can be passed around to other drivers or have separate duties inside + * the same driver for allocation, read and write operations. + * + * Open-coding access to :c:type:`struct iosys_map <iosys_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 iosys_map <iosys_map>` can be initialized statically with + * IOSYS_MAP_INIT_VADDR(), or at runtime with iosys_map_set_vaddr(). These + * helpers will set an address in system memory. + * + * .. code-block:: c + * + * struct iosys_map map = IOSYS_MAP_INIT_VADDR(0xdeadbeaf); + * + * iosys_map_set_vaddr(&map, 0xdeadbeaf); + * + * To set an address in I/O memory, use IOSYS_MAP_INIT_VADDR_IOMEM() or + * iosys_map_set_vaddr_iomem(). + * + * .. code-block:: c + * + * struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(0xdeadbeaf); + * + * iosys_map_set_vaddr_iomem(&map, 0xdeadbeaf); + * + * Instances of struct iosys_map do not have to be cleaned up, but + * can be cleared to NULL with iosys_map_clear(). Cleared mappings + * always refer to system memory. + * + * .. code-block:: c + * + * iosys_map_clear(&map); + * + * Test if a mapping is valid with either iosys_map_is_set() or + * iosys_map_is_null(). + * + * .. code-block:: c + * + * if (iosys_map_is_set(&map) != iosys_map_is_null(&map)) + * // always true + * + * Instances of :c:type:`struct iosys_map <iosys_map>` can be compared for + * equality with iosys_map_is_equal(). Mappings that 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 iosys_map sys_map; // refers to system memory + * struct iosys_map io_map; // refers to I/O memory + * + * if (iosys_map_is_equal(&sys_map, &io_map)) + * // always false + * + * A set up instance of struct iosys_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 + * iosys_map_memcpy_to(). The address can be manipulated with iosys_map_incr(). + * + * .. code-block:: c + * + * const void *src = ...; // source buffer + * size_t len = ...; // length of src + * + * iosys_map_memcpy_to(&map, src, len); + * iosys_map_incr(&map, len); // go to first byte after the memcpy + */ + +/** + * struct iosys_map - Pointer to IO/system 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 buffer is located in I/O memory, or false + * otherwise. + */ +struct iosys_map { + union { + void __iomem *vaddr_iomem; + void *vaddr; + }; + bool is_iomem; +}; + +/** + * IOSYS_MAP_INIT_VADDR - Initializes struct iosys_map to an address in system memory + * @vaddr_: A system-memory address + */ +#define IOSYS_MAP_INIT_VADDR(vaddr_) \ + { \ + .vaddr = (vaddr_), \ + .is_iomem = false, \ + } + +/** + * IOSYS_MAP_INIT_VADDR_IOMEM - Initializes struct iosys_map to an address in I/O memory + * @vaddr_iomem_: An I/O-memory address + */ +#define IOSYS_MAP_INIT_VADDR_IOMEM(vaddr_iomem_) \ + { \ + .vaddr_iomem = (vaddr_iomem_), \ + .is_iomem = true, \ + } + +/** + * IOSYS_MAP_INIT_OFFSET - Initializes struct iosys_map from another iosys_map + * @map_: The dma-buf mapping structure to copy from + * @offset_: Offset to add to the other mapping + * + * Initializes a new iosys_map struct based on another passed as argument. It + * does a shallow copy of the struct so it's possible to update the back storage + * without changing where the original map points to. It is the equivalent of + * doing: + * + * .. code-block:: c + * + * iosys_map map = other_map; + * iosys_map_incr(&map, &offset); + * + * Example usage: + * + * .. code-block:: c + * + * void foo(struct device *dev, struct iosys_map *base_map) + * { + * ... + * struct iosys_map map = IOSYS_MAP_INIT_OFFSET(base_map, FIELD_OFFSET); + * ... + * } + * + * The advantage of using the initializer over just increasing the offset with + * iosys_map_incr() like above is that the new map will always point to the + * right place of the buffer during its scope. It reduces the risk of updating + * the wrong part of the buffer and having no compiler warning about that. If + * the assignment to IOSYS_MAP_INIT_OFFSET() is forgotten, the compiler can warn + * about the use of uninitialized variable. + */ +#define IOSYS_MAP_INIT_OFFSET(map_, offset_) ({ \ + struct iosys_map copy = *map_; \ + iosys_map_incr(©, offset_); \ + copy; \ +}) + +/** + * iosys_map_set_vaddr - Sets a iosys mapping structure to an address in system memory + * @map: The iosys_map structure + * @vaddr: A system-memory address + * + * Sets the address and clears the I/O-memory flag. + */ +static inline void iosys_map_set_vaddr(struct iosys_map *map, void *vaddr) +{ + map->vaddr = vaddr; + map->is_iomem = false; +} + +/** + * iosys_map_set_vaddr_iomem - Sets a iosys mapping structure to an address in I/O memory + * @map: The iosys_map structure + * @vaddr_iomem: An I/O-memory address + * + * Sets the address and the I/O-memory flag. + */ +static inline void iosys_map_set_vaddr_iomem(struct iosys_map *map, + void __iomem *vaddr_iomem) +{ + map->vaddr_iomem = vaddr_iomem; + map->is_iomem = true; +} + +/** + * iosys_map_is_equal - Compares two iosys mapping structures for equality + * @lhs: The iosys_map structure + * @rhs: A iosys_map structure to compare with + * + * Two iosys 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 iosys_map_is_equal(const struct iosys_map *lhs, + const struct iosys_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; +} + +/** + * iosys_map_is_null - Tests for a iosys mapping to be NULL + * @map: The iosys_map structure + * + * Depending on the state of struct iosys_map.is_iomem, tests if the + * mapping is NULL. + * + * Returns: + * True if the mapping is NULL, or false otherwise. + */ +static inline bool iosys_map_is_null(const struct iosys_map *map) +{ + if (map->is_iomem) + return !map->vaddr_iomem; + return !map->vaddr; +} + +/** + * iosys_map_is_set - Tests if the iosys mapping has been set + * @map: The iosys_map structure + * + * Depending on the state of struct iosys_map.is_iomem, tests if the + * mapping has been set. + * + * Returns: + * True if the mapping is been set, or false otherwise. + */ +static inline bool iosys_map_is_set(const struct iosys_map *map) +{ + return !iosys_map_is_null(map); +} + +/** + * iosys_map_clear - Clears a iosys mapping structure + * @map: The iosys_map structure + * + * Clears all fields to zero, including struct iosys_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 iosys_map_clear(struct iosys_map *map) +{ + if (map->is_iomem) { + map->vaddr_iomem = NULL; + map->is_iomem = false; + } else { + map->vaddr = NULL; + } +} + +/** + * iosys_map_memcpy_to - Memcpy into offset of iosys_map + * @dst: The iosys_map structure + * @dst_offset: The offset from which to copy + * @src: The source buffer + * @len: The number of byte in src + * + * Copies data into a iosys_map with an offset. 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 iosys_map_memcpy_to(struct iosys_map *dst, size_t dst_offset, + const void *src, size_t len) +{ + if (dst->is_iomem) + memcpy_toio(dst->vaddr_iomem + dst_offset, src, len); + else + memcpy(dst->vaddr + dst_offset, src, len); +} + +/** + * iosys_map_memcpy_from - Memcpy from iosys_map into system memory + * @dst: Destination in system memory + * @src: The iosys_map structure + * @src_offset: The offset from which to copy + * @len: The number of byte in src + * + * Copies data from a iosys_map with an offset. The dest buffer is in + * system memory. Depending on the mapping location, the helper picks the + * correct method of accessing the memory. + */ +static inline void iosys_map_memcpy_from(void *dst, const struct iosys_map *src, + size_t src_offset, size_t len) +{ + if (src->is_iomem) + memcpy_fromio(dst, src->vaddr_iomem + src_offset, len); + else + memcpy(dst, src->vaddr + src_offset, len); +} + +/** + * iosys_map_incr - Increments the address stored in a iosys mapping + * @map: The iosys_map structure + * @incr: The number of bytes to increment + * + * Increments the address stored in a iosys mapping. Depending on the + * buffer's location, the correct value will be updated. + */ +static inline void iosys_map_incr(struct iosys_map *map, size_t incr) +{ + if (map->is_iomem) + map->vaddr_iomem += incr; + else + map->vaddr += incr; +} + +/** + * iosys_map_memset - Memset iosys_map + * @dst: The iosys_map structure + * @offset: Offset from dst where to start setting value + * @value: The value to set + * @len: The number of bytes to set in dst + * + * Set value in iosys_map. Depending on the buffer's location, the helper + * picks the correct method of accessing the memory. + */ +static inline void iosys_map_memset(struct iosys_map *dst, size_t offset, + int value, size_t len) +{ + if (dst->is_iomem) + memset_io(dst->vaddr_iomem + offset, value, len); + else + memset(dst->vaddr + offset, value, len); +} + +#ifdef CONFIG_64BIT +#define __iosys_map_rd_io_u64_case(val_, vaddr_iomem_) \ + u64: val_ = readq(vaddr_iomem_) +#define __iosys_map_wr_io_u64_case(val_, vaddr_iomem_) \ + u64: writeq(val_, vaddr_iomem_) +#else +#define __iosys_map_rd_io_u64_case(val_, vaddr_iomem_) \ + u64: memcpy_fromio(&(val_), vaddr_iomem_, sizeof(u64)) +#define __iosys_map_wr_io_u64_case(val_, vaddr_iomem_) \ + u64: memcpy_toio(vaddr_iomem_, &(val_), sizeof(u64)) +#endif + +#define __iosys_map_rd_io(val__, vaddr_iomem__, type__) _Generic(val__, \ + u8: val__ = readb(vaddr_iomem__), \ + u16: val__ = readw(vaddr_iomem__), \ + u32: val__ = readl(vaddr_iomem__), \ + __iosys_map_rd_io_u64_case(val__, vaddr_iomem__)) + +#define __iosys_map_rd_sys(val__, vaddr__, type__) \ + val__ = READ_ONCE(*(type__ *)(vaddr__)) + +#define __iosys_map_wr_io(val__, vaddr_iomem__, type__) _Generic(val__, \ + u8: writeb(val__, vaddr_iomem__), \ + u16: writew(val__, vaddr_iomem__), \ + u32: writel(val__, vaddr_iomem__), \ + __iosys_map_wr_io_u64_case(val__, vaddr_iomem__)) + +#define __iosys_map_wr_sys(val__, vaddr__, type__) \ + WRITE_ONCE(*(type__ *)(vaddr__), val__) + +/** + * iosys_map_rd - Read a C-type value from the iosys_map + * + * @map__: The iosys_map structure + * @offset__: The offset from which to read + * @type__: Type of the value being read + * + * Read a C type value (u8, u16, u32 and u64) from iosys_map. For other types or + * if pointer may be unaligned (and problematic for the architecture supported), + * use iosys_map_memcpy_from(). + * + * Returns: + * The value read from the mapping. + */ +#define iosys_map_rd(map__, offset__, type__) ({ \ + type__ val; \ + if ((map__)->is_iomem) { \ + __iosys_map_rd_io(val, (map__)->vaddr_iomem + (offset__), type__);\ + } else { \ + __iosys_map_rd_sys(val, (map__)->vaddr + (offset__), type__); \ + } \ + val; \ +}) + +/** + * iosys_map_wr - Write a C-type value to the iosys_map + * + * @map__: The iosys_map structure + * @offset__: The offset from the mapping to write to + * @type__: Type of the value being written + * @val__: Value to write + * + * Write a C type value (u8, u16, u32 and u64) to the iosys_map. For other types + * or if pointer may be unaligned (and problematic for the architecture + * supported), use iosys_map_memcpy_to() + */ +#define iosys_map_wr(map__, offset__, type__, val__) ({ \ + type__ val = (val__); \ + if ((map__)->is_iomem) { \ + __iosys_map_wr_io(val, (map__)->vaddr_iomem + (offset__), type__);\ + } else { \ + __iosys_map_wr_sys(val, (map__)->vaddr + (offset__), type__); \ + } \ +}) + +/** + * iosys_map_rd_field - Read a member from a struct in the iosys_map + * + * @map__: The iosys_map structure + * @struct_offset__: Offset from the beggining of the map, where the struct + * is located + * @struct_type__: The struct describing the layout of the mapping + * @field__: Member of the struct to read + * + * Read a value from iosys_map considering its layout is described by a C struct + * starting at @struct_offset__. The field offset and size is calculated and its + * value read. If the field access would incur in un-aligned access, then either + * iosys_map_memcpy_from() needs to be used or the architecture must support it. + * For example: suppose there is a @struct foo defined as below and the value + * ``foo.field2.inner2`` needs to be read from the iosys_map: + * + * .. code-block:: c + * + * struct foo { + * int field1; + * struct { + * int inner1; + * int inner2; + * } field2; + * int field3; + * } __packed; + * + * This is the expected memory layout of a buffer using iosys_map_rd_field(): + * + * +------------------------------+--------------------------+ + * | Address | Content | + * +==============================+==========================+ + * | buffer + 0000 | start of mmapped buffer | + * | | pointed by iosys_map | + * +------------------------------+--------------------------+ + * | ... | ... | + * +------------------------------+--------------------------+ + * | buffer + ``struct_offset__`` | start of ``struct foo`` | + * +------------------------------+--------------------------+ + * | ... | ... | + * +------------------------------+--------------------------+ + * | buffer + wwww | ``foo.field2.inner2`` | + * +------------------------------+--------------------------+ + * | ... | ... | + * +------------------------------+--------------------------+ + * | buffer + yyyy | end of ``struct foo`` | + * +------------------------------+--------------------------+ + * | ... | ... | + * +------------------------------+--------------------------+ + * | buffer + zzzz | end of mmaped buffer | + * +------------------------------+--------------------------+ + * + * Values automatically calculated by this macro or not needed are denoted by + * wwww, yyyy and zzzz. This is the code to read that value: + * + * .. code-block:: c + * + * x = iosys_map_rd_field(&map, offset, struct foo, field2.inner2); + * + * Returns: + * The value read from the mapping. + */ +#define iosys_map_rd_field(map__, struct_offset__, struct_type__, field__) ({ \ + struct_type__ *s; \ + iosys_map_rd(map__, struct_offset__ + offsetof(struct_type__, field__), \ + typeof(s->field__)); \ +}) + +/** + * iosys_map_wr_field - Write to a member of a struct in the iosys_map + * + * @map__: The iosys_map structure + * @struct_offset__: Offset from the beggining of the map, where the struct + * is located + * @struct_type__: The struct describing the layout of the mapping + * @field__: Member of the struct to read + * @val__: Value to write + * + * Write a value to the iosys_map considering its layout is described by a C + * struct starting at @struct_offset__. The field offset and size is calculated + * and the @val__ is written. If the field access would incur in un-aligned + * access, then either iosys_map_memcpy_to() needs to be used or the + * architecture must support it. Refer to iosys_map_rd_field() for expected + * usage and memory layout. + */ +#define iosys_map_wr_field(map__, struct_offset__, struct_type__, field__, val__) ({ \ + struct_type__ *s; \ + iosys_map_wr(map__, struct_offset__ + offsetof(struct_type__, field__), \ + typeof(s->field__), val__); \ +}) + +#endif /* __IOSYS_MAP_H__ */ |