1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * Copyright 2013 Broadcom Corporation.
4 */
5
6/*
7 * Bitfield operations
8 *
9 * These are generic bitfield operations which allow manipulation of variable
10 * width bitfields within a word. One use of this would be to use data tables
11 * to determine how to reprogram fields within R/W hardware registers.
12 *
13 * Example:
14 *
15 *            old_reg_val
16 * +--------+----+---+--+-----+----------+
17 * |        |    |   |  | old |          |
18 * +--------+----+---+--+-----+----------+
19 *
20 *            new_reg_val
21 * +--------+----+---+--+-----+----------+
22 * |        |    |   |  | new |          |
23 * +--------+----+---+--+-----+----------+
24 *
25 * mask = bitfield_mask(10, 5);
26 * old = bitfield_extract(old_reg_val, 10, 5);
27 * new_reg_val = bitfield_replace(old_reg_val, 10, 5, new);
28 *
29 * or
30 *
31 * mask = bitfield_mask(10, 5);
32 * old = bitfield_extract_by_mask(old_reg_val, mask);
33 * new_reg_val = bitfield_replace_by_mask(old_reg_val, mask, new);
34 *
35 * The numbers 10 and 5 could for example come from data
36 * tables which describe all bitfields in all registers.
37 */
38
39#include <linux/bitops.h>
40#include <linux/types.h>
41
42/* Produces a mask of set bits covering a range of a uint value */
43static inline uint bitfield_mask(uint shift, uint width)
44{
45	return ((1 << width) - 1) << shift;
46}
47
48/* Extract the value of a bitfield found within a given register value */
49static inline uint bitfield_extract(uint reg_val, uint shift, uint width)
50{
51	return (reg_val & bitfield_mask(shift, width)) >> shift;
52}
53
54/*
55 * Replace the value of a bitfield found within a given register value
56 * Returns the newly modified uint value with the replaced field.
57 */
58static inline uint bitfield_replace(uint reg_val, uint shift, uint width,
59				    uint bitfield_val)
60{
61	uint mask = bitfield_mask(shift, width);
62
63	return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
64}
65
66/* Produces a shift of the bitfield given a mask */
67static inline uint bitfield_shift(uint mask)
68{
69	return mask ? ffs(mask) - 1 : 0;
70}
71
72/* Extract the value of a bitfield found within a given register value */
73static inline uint bitfield_extract_by_mask(uint reg_val, uint mask)
74{
75	uint shift = bitfield_shift(mask);
76
77	return (reg_val & mask) >> shift;
78}
79
80/*
81 * Replace the value of a bitfield found within a given register value
82 * Returns the newly modified uint value with the replaced field.
83 */
84static inline uint bitfield_replace_by_mask(uint reg_val, uint mask,
85					    uint bitfield_val)
86{
87	uint shift = bitfield_shift(mask);
88
89	return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
90}
91