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, 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);
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) != proc[i].id)
178				continue;
179
180			if (!max_entries || count < max_entries)
181				if (call_handler(&proc[i], entry.hdr, 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);
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					sizeof(struct acpi_table_cdat),
229					(union fw_table_header *)table_header,
230					length, &proc, 1, 0);
231}
232EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);
233