lib/fw_table.c

   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
  17 enum acpi_subtable_type {
  18         ACPI_SUBTABLE_COMMON,
  19         ACPI_SUBTABLE_HMAT,
  20         ACPI_SUBTABLE_PRMT,
  21         ACPI_SUBTABLE_CEDT,
  22         CDAT_SUBTABLE,
  23 };
  24
  25 struct acpi_subtable_entry {
  26         union acpi_subtable_headers *hdr;
  27         enum acpi_subtable_type type;
  28 };
  29
  30 static unsigned long __init_or_fwtbl_lib
  31 acpi_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
  48 static unsigned long __init_or_fwtbl_lib
  49 acpi_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
  69 static unsigned long __init_or_fwtbl_lib
  70 acpi_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
  87 static enum acpi_subtable_type __init_or_fwtbl_lib
  88 acpi_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
 101 static unsigned long __init_or_fwtbl_lib
 102 acpi_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
 114 static __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  */
 148 int __init_or_fwtbl_lib
 149 acpi_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
 207 int __init_or_fwtbl_lib
 208 cdat_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 }
 227 EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);