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
apei_read_register(ACPI_GENERIC_ADDRESS * Register,struct apei_mapreg * map,uint64_t Mask)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
apei_write_register(ACPI_GENERIC_ADDRESS * Register,struct apei_mapreg * map,uint64_t Mask,bool preserve_register,uint64_t X)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