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- /* SPDX-License-Identifier: GPL-2.0+ */
- /*
- * Copyright (c) 2022 Sean Anderson <sean.anderson@seco.com>
- */
- #ifndef NVMEM_H
- #define NVMEM_H
- /**
- * DOC: Design
- *
- * The NVMEM subsystem is a "meta-uclass" in that it abstracts over several
- * different uclasses all with read/write APIs. One approach to implementing
- * this could be to add a new sub-device for each nvmem-style device of
- * UCLASS_NVMEM. This subsystem has taken the approach of using the existing
- * access methods (i2c_eeprom_write, misc_write, etc.) directly. This has the
- * advantage of not requiring an extra device/driver, saving on binary size and
- * runtime memory usage. On the other hand, it is not idiomatic. Similar
- * efforts should generally use a new uclass.
- */
- /**
- * struct nvmem_cell - One datum within non-volatile memory
- * @nvmem: The backing storage device
- * @offset: The offset of the cell from the start of @nvmem
- * @size: The size of the cell, in bytes
- */
- struct nvmem_cell {
- struct udevice *nvmem;
- unsigned int offset;
- size_t size;
- };
- struct udevice;
- #if CONFIG_IS_ENABLED(NVMEM)
- /**
- * nvmem_cell_read() - Read the value of an nvmem cell
- * @cell: The nvmem cell to read
- * @buf: The buffer to read into
- * @size: The size of @buf
- *
- * Return:
- * * 0 on success
- * * -EINVAL if @buf is not the same size as @cell.
- * * -ENOSYS if CONFIG_NVMEM is disabled
- * * A negative error if there was a problem reading the underlying storage
- */
- int nvmem_cell_read(struct nvmem_cell *cell, void *buf, size_t size);
- /**
- * nvmem_cell_write() - Write a value to an nvmem cell
- * @cell: The nvmem cell to write
- * @buf: The buffer to write from
- * @size: The size of @buf
- *
- * Return:
- * * 0 on success
- * * -EINVAL if @buf is not the same size as @cell
- * * -ENOSYS if @cell is read-only, or if CONFIG_NVMEM is disabled
- * * A negative error if there was a problem writing the underlying storage
- */
- int nvmem_cell_write(struct nvmem_cell *cell, const void *buf, size_t size);
- /**
- * nvmem_cell_get_by_index() - Get an nvmem cell from a given device and index
- * @dev: The device that uses the nvmem cell
- * @index: The index of the cell in nvmem-cells
- * @cell: The cell to initialize
- *
- * Look up the nvmem cell referenced by the phandle at @index in nvmem-cells in
- * @dev.
- *
- * Return:
- * * 0 on success
- * * -EINVAL if the regs property is missing, empty, or undersized
- * * -ENODEV if the nvmem device is missing or unimplemented
- * * -ENOSYS if CONFIG_NVMEM is disabled
- * * A negative error if there was a problem reading nvmem-cells or getting the
- * device
- */
- int nvmem_cell_get_by_index(struct udevice *dev, int index,
- struct nvmem_cell *cell);
- /**
- * nvmem_cell_get_by_name() - Get an nvmem cell from a given device and name
- * @dev: The device that uses the nvmem cell
- * @name: The name of the nvmem cell
- * @cell: The cell to initialize
- *
- * Look up the nvmem cell referenced by @name in the nvmem-cell-names property
- * of @dev.
- *
- * Return:
- * * 0 on success
- * * -EINVAL if the regs property is missing, empty, or undersized
- * * -ENODEV if the nvmem device is missing or unimplemented
- * * -ENODATA if @name is not in nvmem-cell-names
- * * -ENOSYS if CONFIG_NVMEM is disabled
- * * A negative error if there was a problem reading nvmem-cell-names,
- * nvmem-cells, or getting the device
- */
- int nvmem_cell_get_by_name(struct udevice *dev, const char *name,
- struct nvmem_cell *cell);
- #else /* CONFIG_NVMEM */
- static inline int nvmem_cell_read(struct nvmem_cell *cell, void *buf, int size)
- {
- return -ENOSYS;
- }
- static inline int nvmem_cell_write(struct nvmem_cell *cell, const void *buf,
- int size)
- {
- return -ENOSYS;
- }
- static inline int nvmem_cell_get_by_index(struct udevice *dev, int index,
- struct nvmem_cell *cell)
- {
- return -ENOSYS;
- }
- static inline int nvmem_cell_get_by_name(struct udevice *dev, const char *name,
- struct nvmem_cell *cell)
- {
- return -ENOSYS;
- }
- #endif /* CONFIG_NVMEM */
- #endif /* NVMEM_H */
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