summaryrefslogtreecommitdiff
path: root/include/linux/iosys-map.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/iosys-map.h')
-rw-r--r--include/linux/iosys-map.h459
1 files changed, 459 insertions, 0 deletions
diff --git a/include/linux/iosys-map.h b/include/linux/iosys-map.h
new file mode 100644
index 000000000000..e69a002d5aa4
--- /dev/null
+++ b/include/linux/iosys-map.h
@@ -0,0 +1,459 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Pointer abstraction for IO/system memory
+ */
+
+#ifndef __IOSYS_MAP_H__
+#define __IOSYS_MAP_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_set_vaddr_iomem().
+ *
+ * .. code-block:: c
+ *
+ * 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_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(&copy, 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);
+}
+
+/**
+ * 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 from iosys_map, handling possible un-aligned accesses to
+ * the mapping.
+ *
+ * Returns:
+ * The value read from the mapping.
+ */
+#define iosys_map_rd(map__, offset__, type__) ({ \
+ type__ val; \
+ iosys_map_memcpy_from(&val, map__, offset__, sizeof(val)); \
+ 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 to the iosys_map, handling possible un-aligned accesses
+ * to the mapping.
+ */
+#define iosys_map_wr(map__, offset__, type__, val__) ({ \
+ type__ val = (val__); \
+ iosys_map_memcpy_to(map__, offset__, &val, sizeof(val)); \
+})
+
+/**
+ * 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 handling possible un-aligned memory accesses. 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 handling possible un-aligned memory accesses. 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__ */
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-23 16:15:13 +0300