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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by
* platform or device firmware
*
* Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
* Copyright (C) 2023 Intel Corp.
*/
#include <linux/errno.h>
#include <linux/fw_table.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/types.h>
enum acpi_subtable_type {
ACPI_SUBTABLE_COMMON,
ACPI_SUBTABLE_HMAT,
ACPI_SUBTABLE_PRMT,
ACPI_SUBTABLE_CEDT,
};
struct acpi_subtable_entry {
union acpi_subtable_headers *hdr;
enum acpi_subtable_type type;
};
static unsigned long __init_or_acpilib
acpi_get_entry_type(struct acpi_subtable_entry *entry)
{
switch (entry->type) {
case ACPI_SUBTABLE_COMMON:
return entry->hdr->common.type;
case ACPI_SUBTABLE_HMAT:
return entry->hdr->hmat.type;
case ACPI_SUBTABLE_PRMT:
return 0;
case ACPI_SUBTABLE_CEDT:
return entry->hdr->cedt.type;
}
return 0;
}
static unsigned long __init_or_acpilib
acpi_get_entry_length(struct acpi_subtable_entry *entry)
{
switch (entry->type) {
case ACPI_SUBTABLE_COMMON:
return entry->hdr->common.length;
case ACPI_SUBTABLE_HMAT:
return entry->hdr->hmat.length;
case ACPI_SUBTABLE_PRMT:
return entry->hdr->prmt.length;
case ACPI_SUBTABLE_CEDT:
return entry->hdr->cedt.length;
}
return 0;
}
static unsigned long __init_or_acpilib
acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
{
switch (entry->type) {
case ACPI_SUBTABLE_COMMON:
return sizeof(entry->hdr->common);
case ACPI_SUBTABLE_HMAT:
return sizeof(entry->hdr->hmat);
case ACPI_SUBTABLE_PRMT:
return sizeof(entry->hdr->prmt);
case ACPI_SUBTABLE_CEDT:
return sizeof(entry->hdr->cedt);
}
return 0;
}
static enum acpi_subtable_type __init_or_acpilib
acpi_get_subtable_type(char *id)
{
if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
return ACPI_SUBTABLE_HMAT;
if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
return ACPI_SUBTABLE_PRMT;
if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
return ACPI_SUBTABLE_CEDT;
return ACPI_SUBTABLE_COMMON;
}
static __init_or_acpilib bool has_handler(struct acpi_subtable_proc *proc)
{
return proc->handler || proc->handler_arg;
}
static __init_or_acpilib int call_handler(struct acpi_subtable_proc *proc,
union acpi_subtable_headers *hdr,
unsigned long end)
{
if (proc->handler)
return proc->handler(hdr, end);
if (proc->handler_arg)
return proc->handler_arg(hdr, proc->arg, end);
return -EINVAL;
}
/**
* acpi_parse_entries_array - for each proc_num find a suitable subtable
*
* @id: table id (for debugging purposes)
* @table_size: size of the root table
* @table_header: where does the table start?
* @proc: array of acpi_subtable_proc struct containing entry id
* and associated handler with it
* @proc_num: how big proc is?
* @max_entries: how many entries can we process?
*
* For each proc_num find a subtable with proc->id and run proc->handler
* on it. Assumption is that there's only single handler for particular
* entry id.
*
* The table_size is not the size of the complete ACPI table (the length
* field in the header struct), but only the size of the root table; i.e.,
* the offset from the very first byte of the complete ACPI table, to the
* first byte of the very first subtable.
*
* On success returns sum of all matching entries for all proc handlers.
* Otherwise, -ENODEV or -EINVAL is returned.
*/
int __init_or_acpilib
acpi_parse_entries_array(char *id, unsigned long table_size,
struct acpi_table_header *table_header,
struct acpi_subtable_proc *proc,
int proc_num, unsigned int max_entries)
{
unsigned long table_end, subtable_len, entry_len;
struct acpi_subtable_entry entry;
int count = 0;
int errs = 0;
int i;
table_end = (unsigned long)table_header + table_header->length;
/* Parse all entries looking for a match. */
entry.type = acpi_get_subtable_type(id);
entry.hdr = (union acpi_subtable_headers *)
((unsigned long)table_header + table_size);
subtable_len = acpi_get_subtable_header_length(&entry);
while (((unsigned long)entry.hdr) + subtable_len < table_end) {
if (max_entries && count >= max_entries)
break;
for (i = 0; i < proc_num; i++) {
if (acpi_get_entry_type(&entry) != proc[i].id)
continue;
if (!has_handler(&proc[i]) ||
(!errs &&
call_handler(&proc[i], entry.hdr, table_end))) {
errs++;
continue;
}
proc[i].count++;
break;
}
if (i != proc_num)
count++;
/*
* If entry->length is 0, break from this loop to avoid
* infinite loop.
*/
entry_len = acpi_get_entry_length(&entry);
if (entry_len == 0) {
pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
return -EINVAL;
}
entry.hdr = (union acpi_subtable_headers *)
((unsigned long)entry.hdr + entry_len);
}
if (max_entries && count > max_entries) {
pr_warn("[%4.4s:0x%02x] found the maximum %i entries\n",
id, proc->id, count);
}
return errs ? -EINVAL : count;
}
EXPORT_SYMBOL_GPL(acpi_parse_entries_array);
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