Am 30. März 2026 19:14:19 MESZ schrieb Aswin Murugan <[email protected]>: >Update the nvmem_cell_read() and nvmem_cell_write() documentation to >describe the new bit field operation mode. > >The documentation now clearly explains: > >For bit field mode (nbits > 0):
Thank you for updating this documentation. Please refer to @cell->nbits in the function documentation and also mention @cell->offset. Best regards Heinrich >- Read: extracts the bit field from raw hardware bytes >- Write: performs read-modify-write to preserve other bits >- Requirements: buffer size must be sizeof(u32), cell size <= 4 bytes > >For non-bit-field mode (nbits == 0): >- Read/Write: direct byte-level access >- Requirements: buffer size must equal the cell size > >This helps developers understand when to use each mode and the >associated buffer size requirements. > >Signed-off-by: Aswin Murugan <[email protected]> >--- > include/nvmem.h | 24 ++++++++++++++++++++++-- > 1 file changed, 22 insertions(+), 2 deletions(-) > >diff --git a/include/nvmem.h b/include/nvmem.h >index dd82122f16f..af1d2594bd6 100644 >--- a/include/nvmem.h >+++ b/include/nvmem.h >@@ -47,9 +47,19 @@ struct udevice; > * @buf: The buffer to read into > * @size: The size of @buf > * >+ * For cells with bit fields (nbits > 0), this function: >+ * - Reads the raw bytes from hardware >+ * - Extracts the bit field using bit_offset and nbits >+ * - Returns the extracted value in @buf >+ * - Requires @size == sizeof(u32) and @cell->size <= 4 >+ * >+ * For cells without bit fields (nbits == 0): >+ * - Reads raw bytes directly >+ * - Requires @size == @cell->size >+ * > * Return: > * * 0 on success >- * * -EINVAL if @buf is not the same size as @cell. >+ * * -EINVAL if @size doesn't match requirements > * * -ENOSYS if CONFIG_NVMEM is disabled > * * A negative error if there was a problem reading the underlying storage > */ >@@ -61,9 +71,19 @@ int nvmem_cell_read(struct nvmem_cell *cell, void *buf, >size_t size); > * @buf: The buffer to write from > * @size: The size of @buf > * >+ * For cells with bit fields (nbits > 0), this function: >+ * - Performs Read-Modify-Write to preserve other bits >+ * - Masks and shifts the value to the correct bit position >+ * - Merges with existing bits outside the field >+ * - Requires @size == sizeof(u32) and @cell->size <= 4 >+ * >+ * For cells without bit fields (nbits == 0): >+ * - Writes raw bytes directly >+ * - Requires @size == @cell->size >+ * > * Return: > * * 0 on success >- * * -EINVAL if @buf is not the same size as @cell >+ * * -EINVAL if @size doesn't match requirements > * * -ENOSYS if @cell is read-only, or if CONFIG_NVMEM is disabled > * * A negative error if there was a problem writing the underlying storage > */
