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/acpi.h>
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/string.h>
14#include <linux/types.h>
15#include <linux/fw_table.h>
16
17enum acpi_subtable_type {
18 ACPI_SUBTABLE_COMMON,
19 ACPI_SUBTABLE_HMAT,
20 ACPI_SUBTABLE_PRMT,
21 ACPI_SUBTABLE_CEDT,
22 CDAT_SUBTABLE,
23};
24
25struct acpi_subtable_entry {
26 union acpi_subtable_headers *hdr;
27 enum acpi_subtable_type type;
28};
29
30static unsigned long __init_or_fwtbl_lib
31acpi_get_entry_type(struct acpi_subtable_entry *entry)
32{
33 switch (entry->type) {
34 case ACPI_SUBTABLE_COMMON:
35 return entry->hdr->common.type;
36 case ACPI_SUBTABLE_HMAT:
37 return entry->hdr->hmat.type;
38 case ACPI_SUBTABLE_PRMT:
39 return 0;
40 case ACPI_SUBTABLE_CEDT:
41 return entry->hdr->cedt.type;
42 case CDAT_SUBTABLE:
43 return entry->hdr->cdat.type;
44 }
45 return 0;
46}
47
48static unsigned long __init_or_fwtbl_lib
49acpi_get_entry_length(struct acpi_subtable_entry *entry)
50{
51 switch (entry->type) {
52 case ACPI_SUBTABLE_COMMON:
53 return entry->hdr->common.length;
54 case ACPI_SUBTABLE_HMAT:
55 return entry->hdr->hmat.length;
56 case ACPI_SUBTABLE_PRMT:
57 return entry->hdr->prmt.length;
58 case ACPI_SUBTABLE_CEDT:
59 return entry->hdr->cedt.length;
60 case CDAT_SUBTABLE: {
61 __le16 length = (__force __le16)entry->hdr->cdat.length;
62
63 return le16_to_cpu(length);
64 }
65 }
66 return 0;
67}
68
69static unsigned long __init_or_fwtbl_lib
70acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
71{
72 switch (entry->type) {
73 case ACPI_SUBTABLE_COMMON:
74 return sizeof(entry->hdr->common);
75 case ACPI_SUBTABLE_HMAT:
76 return sizeof(entry->hdr->hmat);
77 case ACPI_SUBTABLE_PRMT:
78 return sizeof(entry->hdr->prmt);
79 case ACPI_SUBTABLE_CEDT:
80 return sizeof(entry->hdr->cedt);
81 case CDAT_SUBTABLE:
82 return sizeof(entry->hdr->cdat);
83 }
84 return 0;
85}
86
87static enum acpi_subtable_type __init_or_fwtbl_lib
88acpi_get_subtable_type(char *id)
89{
90 if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
91 return ACPI_SUBTABLE_HMAT;
92 if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
93 return ACPI_SUBTABLE_PRMT;
94 if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
95 return ACPI_SUBTABLE_CEDT;
96 if (strncmp(id, ACPI_SIG_CDAT, 4) == 0)
97 return CDAT_SUBTABLE;
98 return ACPI_SUBTABLE_COMMON;
99}
100
101static unsigned long __init_or_fwtbl_lib
102acpi_table_get_length(enum acpi_subtable_type type,
103 union fw_table_header *header)
104{
105 if (type == CDAT_SUBTABLE) {
106 __le32 length = (__force __le32)header->cdat.length;
107
108 return le32_to_cpu(length);
109 }
110
111 return header->acpi.length;
112}
113
114static __init_or_fwtbl_lib int call_handler(struct acpi_subtable_proc *proc,
115 union acpi_subtable_headers *hdr,
116 unsigned long end)
117{
118 if (proc->handler)
119 return proc->handler(hdr, end);
120 if (proc->handler_arg)
121 return proc->handler_arg(hdr, proc->arg, end);
122 return -EINVAL;
123}
124
125/**
126 * acpi_parse_entries_array - for each proc_num find a suitable subtable
127 *
128 * @id: table id (for debugging purposes)
129 * @table_size: size of the root table
130 * @max_length: maximum size of the table (ignore if 0)
131 * @table_header: where does the table start?
132 * @proc: array of acpi_subtable_proc struct containing entry id
133 * and associated handler with it
134 * @proc_num: how big proc is?
135 * @max_entries: how many entries can we process?
136 *
137 * For each proc_num find a subtable with proc->id and run proc->handler
138 * on it. Assumption is that there's only single handler for particular
139 * entry id.
140 *
141 * The table_size is not the size of the complete ACPI table (the length
142 * field in the header struct), but only the size of the root table; i.e.,
143 * the offset from the very first byte of the complete ACPI table, to the
144 * first byte of the very first subtable.
145 *
146 * On success returns sum of all matching entries for all proc handlers.
147 * Otherwise, -ENODEV or -EINVAL is returned.
148 */
149int __init_or_fwtbl_lib
150acpi_parse_entries_array(char *id, unsigned long table_size,
151 union fw_table_header *table_header,
152 unsigned long max_length,
153 struct acpi_subtable_proc *proc,
154 int proc_num, unsigned int max_entries)
155{
156 unsigned long table_len, table_end, subtable_len, entry_len;
157 struct acpi_subtable_entry entry;
158 enum acpi_subtable_type type;
159 int count = 0;
160 int i;
161
162 type = acpi_get_subtable_type(id);
163 table_len = acpi_table_get_length(type, header: table_header);
164 if (max_length && max_length < table_len)
165 table_len = max_length;
166 table_end = (unsigned long)table_header + table_len;
167
168 /* Parse all entries looking for a match. */
169
170 entry.type = type;
171 entry.hdr = (union acpi_subtable_headers *)
172 ((unsigned long)table_header + table_size);
173 subtable_len = acpi_get_subtable_header_length(entry: &entry);
174
175 while (((unsigned long)entry.hdr) + subtable_len < table_end) {
176 for (i = 0; i < proc_num; i++) {
177 if (acpi_get_entry_type(entry: &entry) != proc[i].id)
178 continue;
179
180 if (!max_entries || count < max_entries)
181 if (call_handler(proc: &proc[i], hdr: entry.hdr, end: table_end))
182 return -EINVAL;
183
184 proc[i].count++;
185 count++;
186 break;
187 }
188
189 /*
190 * If entry->length is 0, break from this loop to avoid
191 * infinite loop.
192 */
193 entry_len = acpi_get_entry_length(entry: &entry);
194 if (entry_len == 0) {
195 pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
196 return -EINVAL;
197 }
198
199 entry.hdr = (union acpi_subtable_headers *)
200 ((unsigned long)entry.hdr + entry_len);
201 }
202
203 if (max_entries && count > max_entries) {
204 pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
205 id, proc->id, count - max_entries, count);
206 }
207
208 return count;
209}
210
211int __init_or_fwtbl_lib
212cdat_table_parse(enum acpi_cdat_type type,
213 acpi_tbl_entry_handler_arg handler_arg,
214 void *arg,
215 struct acpi_table_cdat *table_header,
216 unsigned long length)
217{
218 struct acpi_subtable_proc proc = {
219 .id = type,
220 .handler_arg = handler_arg,
221 .arg = arg,
222 };
223
224 if (!table_header)
225 return -EINVAL;
226
227 return acpi_parse_entries_array(ACPI_SIG_CDAT,
228 table_size: sizeof(struct acpi_table_cdat),
229 table_header: (union fw_table_header *)table_header,
230 max_length: length, proc: &proc, proc_num: 1, max_entries: 0);
231}
232EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);
233