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 * @table_header: where does the table start?
131 * @proc: array of acpi_subtable_proc struct containing entry id
132 *        and associated handler with it
133 * @proc_num: how big proc is?
134 * @max_entries: how many entries can we process?
135 *
136 * For each proc_num find a subtable with proc->id and run proc->handler
137 * on it. Assumption is that there's only single handler for particular
138 * entry id.
139 *
140 * The table_size is not the size of the complete ACPI table (the length
141 * field in the header struct), but only the size of the root table; i.e.,
142 * the offset from the very first byte of the complete ACPI table, to the
143 * first byte of the very first subtable.
144 *
145 * On success returns sum of all matching entries for all proc handlers.
146 * Otherwise, -ENODEV or -EINVAL is returned.
147 */
148int __init_or_fwtbl_lib
149acpi_parse_entries_array(char *id, unsigned long table_size,
150			 union fw_table_header *table_header,
151			 struct acpi_subtable_proc *proc,
152			 int proc_num, unsigned int max_entries)
153{
154	unsigned long table_end, subtable_len, entry_len;
155	struct acpi_subtable_entry entry;
156	enum acpi_subtable_type type;
157	int count = 0;
158	int i;
159
160	type = acpi_get_subtable_type(id);
161	table_end = (unsigned long)table_header +
162		    acpi_table_get_length(type, table_header);
163
164	/* Parse all entries looking for a match. */
165
166	entry.type = type;
167	entry.hdr = (union acpi_subtable_headers *)
168	    ((unsigned long)table_header + table_size);
169	subtable_len = acpi_get_subtable_header_length(&entry);
170
171	while (((unsigned long)entry.hdr) + subtable_len < table_end) {
172		for (i = 0; i < proc_num; i++) {
173			if (acpi_get_entry_type(&entry) != proc[i].id)
174				continue;
175
176			if (!max_entries || count < max_entries)
177				if (call_handler(&proc[i], entry.hdr, table_end))
178					return -EINVAL;
179
180			proc[i].count++;
181			count++;
182			break;
183		}
184
185		/*
186		 * If entry->length is 0, break from this loop to avoid
187		 * infinite loop.
188		 */
189		entry_len = acpi_get_entry_length(&entry);
190		if (entry_len == 0) {
191			pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
192			return -EINVAL;
193		}
194
195		entry.hdr = (union acpi_subtable_headers *)
196		    ((unsigned long)entry.hdr + entry_len);
197	}
198
199	if (max_entries && count > max_entries) {
200		pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
201			id, proc->id, count - max_entries, count);
202	}
203
204	return count;
205}
206
207int __init_or_fwtbl_lib
208cdat_table_parse(enum acpi_cdat_type type,
209		 acpi_tbl_entry_handler_arg handler_arg,
210		 void *arg,
211		 struct acpi_table_cdat *table_header)
212{
213	struct acpi_subtable_proc proc = {
214		.id		= type,
215		.handler_arg	= handler_arg,
216		.arg		= arg,
217	};
218
219	if (!table_header)
220		return -EINVAL;
221
222	return acpi_parse_entries_array(ACPI_SIG_CDAT,
223					sizeof(struct acpi_table_cdat),
224					(union fw_table_header *)table_header,
225					&proc, 1, 0);
226}
227EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);