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83d290c5 | 1 | /* SPDX-License-Identifier: GPL-2.0+ */ |
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2 | /* |
3 | * Copyright 2013 Broadcom Corporation. | |
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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 | * | |
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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 | * | |
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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/types.h> | |
40 | ||
41 | /* Produces a mask of set bits covering a range of a uint value */ | |
42 | static inline uint bitfield_mask(uint shift, uint width) | |
43 | { | |
44 | return ((1 << width) - 1) << shift; | |
45 | } | |
46 | ||
47 | /* Extract the value of a bitfield found within a given register value */ | |
48 | static inline uint bitfield_extract(uint reg_val, uint shift, uint width) | |
49 | { | |
50 | return (reg_val & bitfield_mask(shift, width)) >> shift; | |
51 | } | |
52 | ||
53 | /* | |
54 | * Replace the value of a bitfield found within a given register value | |
55 | * Returns the newly modified uint value with the replaced field. | |
56 | */ | |
57 | static inline uint bitfield_replace(uint reg_val, uint shift, uint width, | |
58 | uint bitfield_val) | |
59 | { | |
60 | uint mask = bitfield_mask(shift, width); | |
61 | ||
c69abd80 | 62 | return (reg_val & ~mask) | ((bitfield_val << shift) & mask); |
989ce049 | 63 | } |
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64 | |
65 | /* Produces a shift of the bitfield given a mask */ | |
66 | static inline uint bitfield_shift(uint mask) | |
67 | { | |
68 | return mask ? ffs(mask) - 1 : 0; | |
69 | } | |
70 | ||
71 | /* Extract the value of a bitfield found within a given register value */ | |
72 | static inline uint bitfield_extract_by_mask(uint reg_val, uint mask) | |
73 | { | |
74 | uint shift = bitfield_shift(mask); | |
75 | ||
76 | return (reg_val & mask) >> shift; | |
77 | } | |
78 | ||
79 | /* | |
80 | * Replace the value of a bitfield found within a given register value | |
81 | * Returns the newly modified uint value with the replaced field. | |
82 | */ | |
83 | static inline uint bitfield_replace_by_mask(uint reg_val, uint mask, | |
84 | uint bitfield_val) | |
85 | { | |
86 | uint shift = bitfield_shift(mask); | |
87 | ||
88 | return (reg_val & ~mask) | ((bitfield_val << shift) & mask); | |
89 | } |