path: root/drivers/acpi/pptt.c

// SPDX-License-Identifier: GPL-2.0
/*
 * pptt.c - parsing of Processor Properties Topology Table (PPTT)
 *
 * Copyright (C) 2018, ARM
 *
 * This file implements parsing of the Processor Properties Topology Table
 * which is optionally used to describe the processor and cache topology.
 * Due to the relative pointers used throughout the table, this doesn't
 * leverage the existing subtable parsing in the kernel.
 *
 * The PPTT structure is an inverted tree, with each node potentially
 * holding one or two inverted tree data structures describing
 * the caches available at that level. Each cache structure optionally
 * contains properties describing the cache at a given level which can be
 * used to override hardware probed values.
 */
#define pr_fmt(fmt) "ACPI PPTT: " fmt

#include <linux/acpi.h>
#include <linux/cacheinfo.h>
#include <acpi/processor.h>

/*
 * The acpi_pptt_cache_v1 in actbl2.h, which is imported from acpica,
 * only contains the cache_id field rather than all the fields of the
 * Cache Type Structure. Use this alternative structure until it is
 * resolved in acpica.
 */
struct acpi_pptt_cache_v1_full {
	struct acpi_subtable_header header;
	u16 reserved;
	u32 flags;
	u32 next_level_of_cache;
	u32 size;
	u32 number_of_sets;
	u8 associativity;
	u8 attributes;
	u16 line_size;
	u32 cache_id;
} __packed;

static struct acpi_subtable_header *fetch_pptt_subtable(struct acpi_table_header *table_hdr,
							u32 pptt_ref)
{
	struct acpi_subtable_header *entry;

	/* there isn't a subtable at reference 0 */
	if (pptt_ref < sizeof(struct acpi_subtable_header))
		return NULL;

	if (pptt_ref + sizeof(struct acpi_subtable_header) > table_hdr->length)
		return NULL;

	entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr, pptt_ref);

	if (entry->length == 0)
		return NULL;

	if (pptt_ref + entry->length > table_hdr->length)
		return NULL;

	return entry;
}

static struct acpi_pptt_processor *fetch_pptt_node(struct acpi_table_header *table_hdr,
						   u32 pptt_ref)
{
	return (struct acpi_pptt_processor *)fetch_pptt_subtable(table_hdr, pptt_ref);
}

static struct acpi_pptt_cache *fetch_pptt_cache(struct acpi_table_header *table_hdr,
						u32 pptt_ref)
{
	return (struct acpi_pptt_cache *)fetch_pptt_subtable(table_hdr, pptt_ref);
}

static struct acpi_pptt_cache_v1_full *upgrade_pptt_cache(struct acpi_pptt_cache *cache)
{
	if (cache->header.length < sizeof(struct acpi_pptt_cache_v1_full))
		return NULL;

	/* No use for v1 if the only additional field is invalid */
	if (!(cache->flags & ACPI_PPTT_CACHE_ID_VALID))
		return NULL;

	return (struct acpi_pptt_cache_v1_full *)cache;
}

static struct acpi_subtable_header *acpi_get_pptt_resource(struct acpi_table_header *table_hdr,
							   struct acpi_pptt_processor *node,
							   int resource)
{
	u32 *ref;

	if (resource >= node->number_of_priv_resources)
		return NULL;

	ref = ACPI_ADD_PTR(u32, node, sizeof(struct acpi_pptt_processor));
	ref += resource;

	return fetch_pptt_subtable(table_hdr, *ref);
}

static inline bool acpi_pptt_match_type(int table_type, int type)
{
	return ((table_type & ACPI_PPTT_MASK_CACHE_TYPE) == type ||
		table_type & ACPI_PPTT_CACHE_TYPE_UNIFIED & type);
}

/**
 * acpi_pptt_walk_cache() - Attempt to find the requested acpi_pptt_cache
 * @table_hdr: Pointer to the head of the PPTT table
 * @local_level: passed res reflects this cache level
 * @split_levels: Number of split cache levels (data/instruction).
 * @res: cache resource in the PPTT we want to walk
 * @found: returns a pointer to the requested level if found
 * @level: the requested cache level
 * @type: the requested cache type
 *
 * Attempt to find a given cache level, while counting the max number
 * of cache levels for the cache node.
 *
 * Given a pptt resource, verify that it is a cache node, then walk
 * down each level of caches, counting how many levels are found
 * as well as checking the cache type (icache, dcache, unified). If a
 * level & type match, then we set found, and continue the search.
 * Once the entire cache branch has been walked return its max
 * depth.
 *
 * Return: The cache structure and the level we terminated with.
 */
static unsigned int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
					 unsigned int local_level,
					 unsigned int *split_levels,
					 struct acpi_subtable_header *res,
					 struct acpi_pptt_cache **found,
					 unsigned int level, int type)
{
	struct acpi_pptt_cache *cache;

	if (res->type != ACPI_PPTT_TYPE_CACHE)
		return 0;

	cache = (struct acpi_pptt_cache *) res;
	while (cache) {
		local_level++;

		if (!(cache