1 /* $NetBSD: apei_reg.c,v 1.3 2024/03/22 20:48:14 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2024 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * APEI register access for ERST/EINJ action instructions 31 */ 32 33 #include <sys/cdefs.h> 34 __KERNEL_RCSID(0, "$NetBSD: apei_reg.c,v 1.3 2024/03/22 20:48:14 riastradh Exp $"); 35 36 #include <sys/types.h> 37 38 #include <dev/acpi/acpivar.h> 39 #include <dev/acpi/apei_mapreg.h> 40 #include <dev/acpi/apei_reg.h> 41 42 /* 43 * apei_read_register(Register, map, Mask, &X) 44 * 45 * Read from Register mapped at map, shifted out of position and 46 * then masked with Mask, and return the result. 47 * 48 * https://uefi.org/specs/ACPI/6.5/18_Platform_Error_Interfaces.html#read-register 49 * 50 * (I'm guessing this applies to both ERST and EINJ, even though 51 * that section is under the ERST part.) 52 */ 53 uint64_t 54 apei_read_register(ACPI_GENERIC_ADDRESS *Register, struct apei_mapreg *map, 55 uint64_t Mask) 56 { 57 const uint8_t BitOffset = Register->BitOffset; 58 uint64_t X; 59 60 X = apei_mapreg_read(Register, map); 61 X >>= BitOffset; 62 X &= Mask; 63 64 return X; 65 } 66 67 /* 68 * apei_write_register(Register, map, Mask, preserve_register, X) 69 * 70 * Write X, masked with Mask and shifted into position, to 71 * Register, mapped at map, preserving other bits if 72 * preserve_register is true. 73 * 74 * https://uefi.org/specs/ACPI/6.5/18_Platform_Error_Interfaces.html#write-register 75 * 76 * Note: The Preserve Register semantics is based on the clearer 77 * indentation at 78 * https://uefi.org/sites/default/files/resources/ACPI_5_1release.pdf#page=714 79 * which has been lost in more recent versions of the spec. 80 */ 81 void 82 apei_write_register(ACPI_GENERIC_ADDRESS *Register, struct apei_mapreg *map, 83 uint64_t Mask, bool preserve_register, uint64_t X) 84 { 85 const uint8_t BitOffset = Register->BitOffset; 86 87 X &= Mask; 88 X <<= BitOffset; 89 if (preserve_register) { 90 uint64_t Y; 91 92 Y = apei_mapreg_read(Register, map); 93 Y &= ~(Mask << BitOffset); 94 X |= Y; 95 } 96 apei_mapreg_write(Register, map, X); 97 } 98