1*d4496ef3SMasahiro Yamada /* 2*d4496ef3SMasahiro Yamada * Copyright (C) 2014 Felix Fietkau <nbd@nbd.name> 3*d4496ef3SMasahiro Yamada * Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com> 4*d4496ef3SMasahiro Yamada * 5*d4496ef3SMasahiro Yamada * This program is free software; you can redistribute it and/or modify 6*d4496ef3SMasahiro Yamada * it under the terms of the GNU General Public License version 2 7*d4496ef3SMasahiro Yamada * as published by the Free Software Foundation 8*d4496ef3SMasahiro Yamada * 9*d4496ef3SMasahiro Yamada * This program is distributed in the hope that it will be useful, 10*d4496ef3SMasahiro Yamada * but WITHOUT ANY WARRANTY; without even the implied warranty of 11*d4496ef3SMasahiro Yamada * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12*d4496ef3SMasahiro Yamada * GNU General Public License for more details. 13*d4496ef3SMasahiro Yamada */ 14*d4496ef3SMasahiro Yamada 15*d4496ef3SMasahiro Yamada #ifndef _LINUX_BITFIELD_H 16*d4496ef3SMasahiro Yamada #define _LINUX_BITFIELD_H 17*d4496ef3SMasahiro Yamada 18*d4496ef3SMasahiro Yamada #include <linux/bug.h> 19*d4496ef3SMasahiro Yamada 20*d4496ef3SMasahiro Yamada /* 21*d4496ef3SMasahiro Yamada * Bitfield access macros 22*d4496ef3SMasahiro Yamada * 23*d4496ef3SMasahiro Yamada * FIELD_{GET,PREP} macros take as first parameter shifted mask 24*d4496ef3SMasahiro Yamada * from which they extract the base mask and shift amount. 25*d4496ef3SMasahiro Yamada * Mask must be a compilation time constant. 26*d4496ef3SMasahiro Yamada * 27*d4496ef3SMasahiro Yamada * Example: 28*d4496ef3SMasahiro Yamada * 29*d4496ef3SMasahiro Yamada * #define REG_FIELD_A GENMASK(6, 0) 30*d4496ef3SMasahiro Yamada * #define REG_FIELD_B BIT(7) 31*d4496ef3SMasahiro Yamada * #define REG_FIELD_C GENMASK(15, 8) 32*d4496ef3SMasahiro Yamada * #define REG_FIELD_D GENMASK(31, 16) 33*d4496ef3SMasahiro Yamada * 34*d4496ef3SMasahiro Yamada * Get: 35*d4496ef3SMasahiro Yamada * a = FIELD_GET(REG_FIELD_A, reg); 36*d4496ef3SMasahiro Yamada * b = FIELD_GET(REG_FIELD_B, reg); 37*d4496ef3SMasahiro Yamada * 38*d4496ef3SMasahiro Yamada * Set: 39*d4496ef3SMasahiro Yamada * reg = FIELD_PREP(REG_FIELD_A, 1) | 40*d4496ef3SMasahiro Yamada * FIELD_PREP(REG_FIELD_B, 0) | 41*d4496ef3SMasahiro Yamada * FIELD_PREP(REG_FIELD_C, c) | 42*d4496ef3SMasahiro Yamada * FIELD_PREP(REG_FIELD_D, 0x40); 43*d4496ef3SMasahiro Yamada * 44*d4496ef3SMasahiro Yamada * Modify: 45*d4496ef3SMasahiro Yamada * reg &= ~REG_FIELD_C; 46*d4496ef3SMasahiro Yamada * reg |= FIELD_PREP(REG_FIELD_C, c); 47*d4496ef3SMasahiro Yamada */ 48*d4496ef3SMasahiro Yamada 49*d4496ef3SMasahiro Yamada #define __bf_shf(x) (__builtin_ffsll(x) - 1) 50*d4496ef3SMasahiro Yamada 51*d4496ef3SMasahiro Yamada #define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \ 52*d4496ef3SMasahiro Yamada ({ \ 53*d4496ef3SMasahiro Yamada BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \ 54*d4496ef3SMasahiro Yamada _pfx "mask is not constant"); \ 55*d4496ef3SMasahiro Yamada BUILD_BUG_ON_MSG(!(_mask), _pfx "mask is zero"); \ 56*d4496ef3SMasahiro Yamada BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ 57*d4496ef3SMasahiro Yamada ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \ 58*d4496ef3SMasahiro Yamada _pfx "value too large for the field"); \ 59*d4496ef3SMasahiro Yamada BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull, \ 60*d4496ef3SMasahiro Yamada _pfx "type of reg too small for mask"); \ 61*d4496ef3SMasahiro Yamada __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \ 62*d4496ef3SMasahiro Yamada (1ULL << __bf_shf(_mask))); \ 63*d4496ef3SMasahiro Yamada }) 64*d4496ef3SMasahiro Yamada 65*d4496ef3SMasahiro Yamada /** 66*d4496ef3SMasahiro Yamada * FIELD_FIT() - check if value fits in the field 67*d4496ef3SMasahiro Yamada * @_mask: shifted mask defining the field's length and position 68*d4496ef3SMasahiro Yamada * @_val: value to test against the field 69*d4496ef3SMasahiro Yamada * 70*d4496ef3SMasahiro Yamada * Return: true if @_val can fit inside @_mask, false if @_val is too big. 71*d4496ef3SMasahiro Yamada */ 72*d4496ef3SMasahiro Yamada #define FIELD_FIT(_mask, _val) \ 73*d4496ef3SMasahiro Yamada ({ \ 74*d4496ef3SMasahiro Yamada __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_FIT: "); \ 75*d4496ef3SMasahiro Yamada !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \ 76*d4496ef3SMasahiro Yamada }) 77*d4496ef3SMasahiro Yamada 78*d4496ef3SMasahiro Yamada /** 79*d4496ef3SMasahiro Yamada * FIELD_PREP() - prepare a bitfield element 80*d4496ef3SMasahiro Yamada * @_mask: shifted mask defining the field's length and position 81*d4496ef3SMasahiro Yamada * @_val: value to put in the field 82*d4496ef3SMasahiro Yamada * 83*d4496ef3SMasahiro Yamada * FIELD_PREP() masks and shifts up the value. The result should 84*d4496ef3SMasahiro Yamada * be combined with other fields of the bitfield using logical OR. 85*d4496ef3SMasahiro Yamada */ 86*d4496ef3SMasahiro Yamada #define FIELD_PREP(_mask, _val) \ 87*d4496ef3SMasahiro Yamada ({ \ 88*d4496ef3SMasahiro Yamada __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \ 89*d4496ef3SMasahiro Yamada ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \ 90*d4496ef3SMasahiro Yamada }) 91*d4496ef3SMasahiro Yamada 92*d4496ef3SMasahiro Yamada /** 93*d4496ef3SMasahiro Yamada * FIELD_GET() - extract a bitfield element 94*d4496ef3SMasahiro Yamada * @_mask: shifted mask defining the field's length and position 95*d4496ef3SMasahiro Yamada * @_reg: 32bit value of entire bitfield 96*d4496ef3SMasahiro Yamada * 97*d4496ef3SMasahiro Yamada * FIELD_GET() extracts the field specified by @_mask from the 98*d4496ef3SMasahiro Yamada * bitfield passed in as @_reg by masking and shifting it down. 99*d4496ef3SMasahiro Yamada */ 100*d4496ef3SMasahiro Yamada #define FIELD_GET(_mask, _reg) \ 101*d4496ef3SMasahiro Yamada ({ \ 102*d4496ef3SMasahiro Yamada __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \ 103*d4496ef3SMasahiro Yamada (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \ 104*d4496ef3SMasahiro Yamada }) 105*d4496ef3SMasahiro Yamada 106*d4496ef3SMasahiro Yamada #endif 107