blob: ec4815c8e05179508c00cce24655acd7382ba62e
1 | /* |
2 | * Copyright 2013 Broadcom Corporation. |
3 | * |
4 | * SPDX-License-Identifier: GPL-2.0+ |
5 | */ |
6 | |
7 | /* |
8 | * Bitfield operations |
9 | * |
10 | * These are generic bitfield operations which allow manipulation of variable |
11 | * width bitfields within a word. One use of this would be to use data tables |
12 | * to determine how to reprogram fields within R/W hardware registers. |
13 | * |
14 | * Example: |
15 | * |
16 | * old_reg_val |
17 | * +--------+----+---+--+-----+----------+ |
18 | * | | | | | old | | |
19 | * +--------+----+---+--+-----+----------+ |
20 | * |
21 | * new_reg_val |
22 | * +--------+----+---+--+-----+----------+ |
23 | * | | | | | new | | |
24 | * +--------+----+---+--+-----+----------+ |
25 | * |
26 | * mask = bitfield_mask(10, 5); |
27 | * old = bitfield_extract(old_reg_val, 10, 5); |
28 | * new_reg_val = bitfield_replace(old_reg_val, 10, 5, new); |
29 | * |
30 | * The numbers 10 and 5 could for example come from data |
31 | * tables which describe all bitfields in all registers. |
32 | */ |
33 | |
34 | #include <linux/types.h> |
35 | |
36 | /* Produces a mask of set bits covering a range of a uint value */ |
37 | static inline uint bitfield_mask(uint shift, uint width) |
38 | { |
39 | return ((1 << width) - 1) << shift; |
40 | } |
41 | |
42 | /* Extract the value of a bitfield found within a given register value */ |
43 | static inline uint bitfield_extract(uint reg_val, uint shift, uint width) |
44 | { |
45 | return (reg_val & bitfield_mask(shift, width)) >> shift; |
46 | } |
47 | |
48 | /* |
49 | * Replace the value of a bitfield found within a given register value |
50 | * Returns the newly modified uint value with the replaced field. |
51 | */ |
52 | static inline uint bitfield_replace(uint reg_val, uint shift, uint width, |
53 | uint bitfield_val) |
54 | { |
55 | uint mask = bitfield_mask(shift, width); |
56 | |
57 | return (reg_val & ~mask) | (bitfield_val << shift); |
58 | } |
59 |