/* 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__ */
