1/* SPDX-License-Identifier: BSD-3-Clause
2 * Copyright 2016-2018 NXP
3 * Copyright (c) 2018-2019, Vladimir Oltean <olteanv@gmail.com>
4 */
5#ifndef _LINUX_PACKING_H
6#define _LINUX_PACKING_H
7
8#include <linux/types.h>
9#include <linux/bitops.h>
10
11#define QUIRK_MSB_ON_THE_RIGHT	BIT(0)
12#define QUIRK_LITTLE_ENDIAN	BIT(1)
13#define QUIRK_LSW32_IS_FIRST	BIT(2)
14
15enum packing_op {
16	PACK,
17	UNPACK,
18};
19
20/**
21 * packing - Convert numbers (currently u64) between a packed and an unpacked
22 *	     format. Unpacked means laid out in memory in the CPU's native
23 *	     understanding of integers, while packed means anything else that
24 *	     requires translation.
25 *
26 * @pbuf: Pointer to a buffer holding the packed value.
27 * @uval: Pointer to an u64 holding the unpacked value.
28 * @startbit: The index (in logical notation, compensated for quirks) where
29 *	      the packed value starts within pbuf. Must be larger than, or
30 *	      equal to, endbit.
31 * @endbit: The index (in logical notation, compensated for quirks) where
32 *	    the packed value ends within pbuf. Must be smaller than, or equal
33 *	    to, startbit.
34 * @op: If PACK, then uval will be treated as const pointer and copied (packed)
35 *	into pbuf, between startbit and endbit.
36 *	If UNPACK, then pbuf will be treated as const pointer and the logical
37 *	value between startbit and endbit will be copied (unpacked) to uval.
38 * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
39 *	    QUIRK_MSB_ON_THE_RIGHT.
40 *
41 * Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming
42 *	   correct usage, return code may be discarded.
43 *	   If op is PACK, pbuf is modified.
44 *	   If op is UNPACK, uval is modified.
45 */
46int packing(void *pbuf, u64 *uval, int startbit, int endbit, size_t pbuflen,
47	    enum packing_op op, u8 quirks);
48
49#endif
50