1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by
4 * platform or device firmware
5 *
6 * Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
7 * Copyright (C) 2023 Intel Corp.
8 */
9#include <linux/errno.h>
10#include <linux/fw_table.h>
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/string.h>
14#include <linux/types.h>
15
16enum acpi_subtable_type {
17 ACPI_SUBTABLE_COMMON,
18 ACPI_SUBTABLE_HMAT,
19 ACPI_SUBTABLE_PRMT,
20 ACPI_SUBTABLE_CEDT,
21};
22
23struct acpi_subtable_entry {
24 union acpi_subtable_headers *hdr;
25 enum acpi_subtable_type type;
26};
27
28static unsigned long __init_or_acpilib
29acpi_get_entry_type(struct acpi_subtable_entry *entry)
30{
31 switch (entry->type) {
32 case ACPI_SUBTABLE_COMMON:
33 return entry->hdr->common.type;
34 case ACPI_SUBTABLE_HMAT:
35 return entry->hdr->hmat.type;
36 case ACPI_SUBTABLE_PRMT:
37 return 0;
38 case ACPI_SUBTABLE_CEDT:
39 return entry->hdr->cedt.type;
40 }
41 return 0;
42}
43
44static unsigned long __init_or_acpilib
45acpi_get_entry_length(struct acpi_subtable_entry *entry)
46{
47 switch (entry->type) {
48 case ACPI_SUBTABLE_COMMON:
49 return entry->hdr->common.length;
50 case ACPI_SUBTABLE_HMAT:
51 return entry->hdr->hmat.length;
52 case ACPI_SUBTABLE_PRMT:
53 return entry->hdr->prmt.length;
54 case ACPI_SUBTABLE_CEDT:
55 return entry->hdr->cedt.length;
56 }
57 return 0;
58}
59
60static unsigned long __init_or_acpilib
61acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
62{
63 switch (entry->type) {
64 case ACPI_SUBTABLE_COMMON:
65 return sizeof(entry->hdr->common);
66 case ACPI_SUBTABLE_HMAT:
67 return sizeof(entry->hdr->hmat);
68 case ACPI_SUBTABLE_PRMT:
69 return sizeof(entry->hdr->prmt);
70 case ACPI_SUBTABLE_CEDT:
71 return sizeof(entry->hdr->cedt);
72 }
73 return 0;
74}
75
76static enum acpi_subtable_type __init_or_acpilib
77acpi_get_subtable_type(char *id)
78{
79 if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
80 return ACPI_SUBTABLE_HMAT;
81 if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
82 return ACPI_SUBTABLE_PRMT;
83 if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
84 return ACPI_SUBTABLE_CEDT;
85 return ACPI_SUBTABLE_COMMON;
86}
87
88static __init_or_acpilib bool has_handler(struct acpi_subtable_proc *proc)
89{
90 return proc->handler || proc->handler_arg;
91}
92
93static __init_or_acpilib int call_handler(struct acpi_subtable_proc *proc,
94 union acpi_subtable_headers *hdr,
95 unsigned long end)
96{
97 if (proc->handler)
98 return proc->handler(hdr, end);
99 if (proc->handler_arg)
100 return proc->handler_arg(hdr, proc->arg, end);
101 return -EINVAL;
102}
103
104/**
105 * acpi_parse_entries_array - for each proc_num find a suitable subtable
106 *
107 * @id: table id (for debugging purposes)
108 * @table_size: size of the root table
109 * @table_header: where does the table start?
110 * @proc: array of acpi_subtable_proc struct containing entry id
111 * and associated handler with it
112 * @proc_num: how big proc is?
113 * @max_entries: how many entries can we process?
114 *
115 * For each proc_num find a subtable with proc->id and run proc->handler
116 * on it. Assumption is that there's only single handler for particular
117 * entry id.
118 *
119 * The table_size is not the size of the complete ACPI table (the length
120 * field in the header struct), but only the size of the root table; i.e.,
121 * the offset from the very first byte of the complete ACPI table, to the
122 * first byte of the very first subtable.
123 *
124 * On success returns sum of all matching entries for all proc handlers.
125 * Otherwise, -ENODEV or -EINVAL is returned.
126 */
127int __init_or_acpilib
128acpi_parse_entries_array(char *id, unsigned long table_size,
129 struct acpi_table_header *table_header,
130 struct acpi_subtable_proc *proc,
131 int proc_num, unsigned int max_entries)
132{
133 unsigned long table_end, subtable_len, entry_len;
134 struct acpi_subtable_entry entry;
135 int count = 0;
136 int errs = 0;
137 int i;
138
139 table_end = (unsigned long)table_header + table_header->length;
140
141 /* Parse all entries looking for a match. */
142
143 entry.type = acpi_get_subtable_type(id);
144 entry.hdr = (union acpi_subtable_headers *)
145 ((unsigned long)table_header + table_size);
146 subtable_len = acpi_get_subtable_header_length(entry: &entry);
147
148 while (((unsigned long)entry.hdr) + subtable_len < table_end) {
149 if (max_entries && count >= max_entries)
150 break;
151
152 for (i = 0; i < proc_num; i++) {
153 if (acpi_get_entry_type(entry: &entry) != proc[i].id)
154 continue;
155 if (!has_handler(proc: &proc[i]) ||
156 (!errs &&
157 call_handler(proc: &proc[i], hdr: entry.hdr, end: table_end))) {
158 errs++;
159 continue;
160 }
161
162 proc[i].count++;
163 break;
164 }
165 if (i != proc_num)
166 count++;
167
168 /*
169 * If entry->length is 0, break from this loop to avoid
170 * infinite loop.
171 */
172 entry_len = acpi_get_entry_length(entry: &entry);
173 if (entry_len == 0) {
174 pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
175 return -EINVAL;
176 }
177
178 entry.hdr = (union acpi_subtable_headers *)
179 ((unsigned long)entry.hdr + entry_len);
180 }
181
182 if (max_entries && count > max_entries) {
183 pr_warn("[%4.4s:0x%02x] found the maximum %i entries\n",
184 id, proc->id, count);
185 }
186
187 return errs ? -EINVAL : count;
188}
189

source code of linux/lib/fw_table.c