// SPDX-License-Identifier: GPL-2.0-only
/*
 * Processor cache information made available to userspace via sysfs;
 * intended to be compatible with x86 intel_cacheinfo implementation.
 *
 * Copyright 2008 IBM Corporation
 * Author: Nathan Lynch
 */

#define pr_fmt(fmt) "cacheinfo: " fmt

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <asm/prom.h>
#include <asm/cputhreads.h>
#include <asm/smp.h>

#include "cacheinfo.h"

/* per-cpu object for tracking:
 * - a "cache" kobject for the top-level directory
 * - a list of "index" objects representing the cpu's local cache hierarchy
 */
struct cache_dir {
        struct kobject *kobj; /* bare (not embedded) kobject for cache
                               * directory */
        struct cache_index_dir *index; /* list of index objects */
};

/* "index" object: each cpu's cache directory has an index
 * subdirectory corresponding to a cache object associated with the
 * cpu.  This object's lifetime is managed via the embedded kobject.
 */
struct cache_index_dir {
        struct kobject kobj;
        struct cache_index_dir *next; /* next index in parent directory */
        struct cache *cache;
};

/* Template for determining which OF properties to query for a given
 * cache type */
struct cache_type_info {
        const char *name;
        const char *size_prop;

        /* Allow for both [di]-cache-line-size and
         * [di]-cache-block-size properties.  According to the PowerPC
         * Processor binding, -line-size should be provided if it
         * differs from the cache block size (that which is operated
         * on by cache instructions), so we look for -line-size first.
         * See cache_get_line_size(). */

        const char *line_size_props[2];
        const char *nr_sets_prop;
};

/* These are used to index the cache_type_info array. */
#define CACHE_TYPE_UNIFIED     0 /* cache-size, cache-block-size, etc. */
#define CACHE_TYPE_UNIFIED_D   1 /* d-cache-size, d-cache-block-size, etc */
#define CACHE_TYPE_INSTRUCTION 2
#define CACHE_TYPE_DATA        3

static const struct cache_type_info cache_type_info[] = {
        {
                /* Embedded systems that use cache-size, cache-block-size,
                 * etc. for the Unified (typically L2) cache. */
                .name            = "Unified",
                .size_prop       = "cache-size",
                .line_size_props = { "cache-line-size",
                                     "cache-block-size", },
                .nr_sets_prop    = "cache-sets",
        },
        {
                /* PowerPC Processor binding says the [di]-cache-*
                 * must be equal on unified caches, so just use
                 * d-cache properties. */
                .name            = "Unified",
                .size_prop       = "d-cache-size",
                .line_size_props = { "d-cache-line-size",
                                     "d-cache-block-size", },
                .nr_sets_prop    = "d-cache-sets",
        },
        {
                .name            = "Instruction",
                .size_prop       = "i-cache-size",
                .line_size_props = { "i-cache-line-size",
                                     "i-cache-block-size", },
                .nr_sets_prop    = "i-cache-sets",
        },
        {
                .name            = "Data",
                .size_prop       = "d-cache-size",
                .line_size_props = { "d-cache-line-size",
                                     "d-cache-block-size", },
                .nr_sets_prop    = "d-cache-sets",
        },
};

/* Cache object: each instance of this corresponds to a distinct cache
 * in the system.  There are separate objects for Harvard caches: one
 * each for instruction and data, and each refers to the same OF node.
 * The refcount of the OF node is elevated for the lifetime of the
 * cache object.  A cache object is released when its shared_cpu_map
 * is cleared (see cache_cpu_clear).
 *
 * A cache object is on two lists: an unsorted global list
 * (cache_list) of cache objects; and a singly-linked list
 * representing the local cache hierarchy, which is ordered by level
 * (e.g. L1d -> L1i -> L2 -> L3).
 */
struct cache {
        struct device_node *ofnode;    /* OF node for this cache, may be cpu */
        struct cpumask shared_cpu_map; /* online CPUs using this cache */
        int type;                      /* split cache disambiguation */
        int level;                     /* level not explicit in device tree */
        int group_id;                  /* id of the group of threads that share this cache */
        struct list_head list;         /* global list of cache objects */
        struct cache *next_local;      /* next cache of >= level */
};

static DEFINE_PER_CPU(struct cache_dir *, cache_dir_pcpu);

/* traversal/modification of this list occurs only at cpu hotplug time;
 * access is serialized by cpu hotplug locking
 */
static LIST_HEAD(cache_list);

static struct cache_index_dir *kobj_to_cache_index_dir(struct kobject *k)
{
        return container_of(k, struct cache_index_dir, kobj);
}

static const char *cache_type_string(const struct cache *cache)
{
        return cache_type_info[cache->type].name;
}

static void cache_init(struct cache *cache, int type, int level,
                       struct device_node *ofnode, int group_id)
{
        cache->type = type;
        cache->level = level;
        cache->ofnode = of_node_get(ofnode);
        cache->group_id = group_id;
        INIT_LIST_HEAD(&cache->list);
        list_add(&cache->list, &cache_list);
}

static struct cache *new_cache(int type, int level,
                               struct device_node *ofnode, int group_id)
{
        struct cache *cache;

        cache = kzalloc(sizeof(*cache), GFP_KERNEL);
        if (cache)
                cache_init(cache, type, level, ofnode, group_id);

        return cache;
}

static void release_cache_debugcheck(struct cache *cache)
{
        struct cache *iter;

        list_for_each_entry(iter, &cache_list, list)
                WARN_ONCE(iter->next_local == cache,
                          "cache for %pOFP(%s) refers to cache for %pOFP(%s)\n",
                          iter->ofnode,
                          cache_type_string(iter),
                          cache->ofnode,
                          cache_type_string(cache));
}

static void release_cache(struct cache *cache)
{
        if (!cache)
                return;

        pr_debug("freeing L%d %s cache for %pOFP\n", cache->level,
                 cache_type_string(cache), cache->ofnode);

        release_cache_debugcheck(cache);
        list_del(&cache->list);
        of_node_put(cache->ofnode);
        kfree(cache);
}

static void cache_cpu_set(struct cache *cache, int cpu)
{
        struct cache *next = cache;

        while (next) {
                WARN_ONCE(cpumask_test_cpu(cpu, &next->shared_cpu_map),
                          "CPU %i already accounted in %pOFP(%s)\n",
                          cpu, next->ofnode,
                          cache_type_string(next));
                cpumask_set_cpu(cpu, &next->shared_cpu_map);
                next = next->next_local;
        }
}

static int cache_size(const struct cache *cache, unsigned int *ret)
{
        const char *propname;
        const __be32 *cache_size;

        propname = cache_type_info[cache->type].size_prop;

        cache_size = of_get_property(cache->ofnode, propname, NULL);
        if (!cache_size)
                return -ENODEV;

        *ret = of_read_number(cache_size, 1);
        return 0;
}

static int cache_size_kb(const struct cache *cache, unsigned int *ret)
{
        unsigned int size;

        if (cache_size(cache, &size))
                return -ENODEV;

        *ret = size / 1024;
        return 0;
}

/* not cache_line_size() because that's a macro in include/linux/cache.h */
static int cache_get_line_size(const struct cache *cache, unsigned int *ret)
{
        const __be32 *line_size;
        int i, lim;

        lim = ARRAY_SIZE(cache_type_info[cache->type].line_size_props);

        for (i = 0; i < lim; i++) {
                const char *propname;

                propname = cache_type_info[cache->type].line_size_props[i];
                line_size = of_get_property(cache->ofnode, propname, NULL);
                if (line_size)
                        break;
        }

        if (!line_size)
                return -ENODEV;

        *ret = of_read_number(line_size, 1);
        return 0;
}

static int cache_nr_sets(const struct cache *cache, unsigned int *ret)
{
        const char *propname;
        const __be32 *nr_sets;

        propname = cache_type_info[cache->type].nr_sets_prop;

        nr_sets = of_get_property(cache->ofnode, propname, NULL);
        if (!nr_sets)
                return -ENODEV;

        *ret = of_read_number(nr_sets, 1);
        return 0;
}

static int cache_associativity(const struct cache *cache, unsigned int *ret)
{
        unsigned int line_size;
        unsigned int nr_sets;
        unsigned int size;

        if (cache_nr_sets(cache, &nr_sets))
                goto err;

        /* If the cache is fully associative, there is no need to
         * check the other properties.
         */
        if (nr_sets == 1) {
                *ret = 0;
                return 0;
        }

        if (cache_get_line_size(cache, &line_size))
                goto err;
        if (cache_size(cache, &size))
                goto err;

        if (!(nr_sets > 0 && size > 0 && line_size > 0))
                goto err;

        *ret = (size / nr_sets) / line_size;
        return 0;
err:
        return -ENODEV;
}

/* helper for dealing with split caches */
static struct cache *cache_find_first_sibling(struct cache *cache)
{
        struct cache *iter;

        if (cache->type == CACHE_TYPE_UNIFIED ||
            cache->type == CACHE_TYPE_UNIFIED_D)
                return cache;

        list_for_each_entry(iter, &cache_list, list)
                if (iter->ofnode == cache->ofnode &&
                    iter->group_id == cache->group_id &&
                    iter->next_local == cache)
                        return iter;

        return cache;
}

/* return the first cache on a local list matching node and thread-group id */
static struct cache *cache_lookup_by_node_group(const struct device_node *node,
                                                int group_id)
{
        struct cache *cache = NULL;
        struct cache *iter;

        list_for_each_entry(iter, &cache_list, list) {
                if (iter->ofnode != node ||
                    iter->group_id != group_id)
                        continue;
                cache = cache_find_first_sibling(iter);
                break;
        }

        return cache;
}

static bool cache_node_is_unified(const struct device_node *np)
{
        return of_get_property(np, "cache-unified", NULL);
}

/*
 * Unified caches can have two different sets of tags.  Most embedded
 * use cache-size, etc. for the unified cache size, but open firmware systems
 * use d-cache-size, etc.   Check on initialization for which type we have, and
 * return the appropriate structure type.  Assume it's embedded if it isn't
 * open firmware.  If it's yet a 3rd type, then there will be missing entries
 * in /sys/devices/system/cpu/cpu0/cache/index2/, and this code will need
 * to be extended further.
 */
static int cache_is_unified_d(const struct device_node *np)
{
        return of_get_property(np,
                cache_type_info[CACHE_TYPE_UNIFIED_D].size_prop, NULL) ?
                CACHE_TYPE_UNIFIED_D : CACHE_TYPE_UNIFIED;
}

static struct cache *cache_do_one_devnode_unified(struct device_node *node, int group_id,
                                                  int level)
{
        pr_debug("creating L%d ucache for %pOFP\n", level, node);

        return new_cache(cache_is_unified_d(node), level, node, group_id);
}

static struct cache *cache_do_one_devnode_split(struct device_node *node, int group_id,
                                                int level)
{
        struct cache *dcache, *icache;

        pr_debug("creating L%d dcache and icache for %pOFP\n", level,
                 node);

        dcache = new_cache(CACHE_TYPE_DATA, level, node, group_id);
        icache = new_cache(CACHE_TYPE_INSTRUCTION, level, node, group_id);

        if (!dcache || !icache)
                goto err;

        dcache->next_local = icache;

        return dcache;
err:
        release_cache(dcache);
        release_cache(icache);
        return NULL;
}

static struct cache *cache_do_one_devnode(struct device_node *node, int group_id, int level)
{
        struct cache *cache;

        if (cache_node_is_unified(node))
                cache = cache_do_one_devnode_unified(node, group_id, level);
        else
                cache = cache_do_one_devnode_split(node, group_id, level);

        return cache;
}

static struct cache *cache_lookup_or_instantiate(struct device_node *node,
                                                 int group_id,
                                                 int level)
{
        struct cache *cache;

        cache = cache_lookup_by_node_group(node, group_id);

        WARN_ONCE(cache && cache->level != level,
                  "cache level mismatch on lookup (got %d, expected %d)\n",
                  cache->level, level);

        if (!cache)
                cache = cache_do_one_devnode(node, group_id, level);

        return cache;
}

static void link_cache_lists(struct cache *smaller, struct cache *bigger)
{
        while (smaller->next_local) {
                if (smaller->next_local == bigger)
                        return; /* already linked */
                smaller = smaller->next_local;
        }

        smaller->next_local = bigger;

        /*
         * The cache->next_local list sorts by level ascending:
         * L1d -> L1i -> L2 -> L3 ...
         */
        WARN_ONCE((smaller->level == 1 && bigger->level > 2) ||
                  (smaller->level > 1 && bigger->level != smaller->level + 1),
                  "linking L%i cache %pOFP to L%i cache %pOFP; skipped a level?\n",
                  smaller->level, smaller->ofnode, bigger->level, bigger->ofnode);
}

static void do_subsidiary_caches_debugcheck(struct cache *cache)
{
        WARN_ONCE(cache->level != 1,
                  "instantiating cache chain from L%d %s cache for "
                  "%pOFP instead of an L1\n", cache->level,
                  cache_type_string(cache), cache->ofnode);
        WARN_ONCE(!of_node_is_type(cache->ofnode, "cpu"),
                  "instantiating cache chain from node %pOFP of type '%s' "
                  "instead of a cpu node\n", cache->ofnode,
                  of_node_get_device_type(cache->ofnode));
}

/*
 * If sub-groups of threads in a core containing @cpu_id share the
 * L@level-cache (information obtained via "ibm,thread-groups"
 * device-tree property), then we identify the group by the first
 * thread-sibling in the group. We define this to be the group-id.
 *
 * In the absence of any thread-group information for L@level-cache,
 * this function returns -1.
 */
static int get_group_id(unsigned int cpu_id, int level)
{
        if (has_big_cores && level == 1)
                return cpumask_first(per_cpu(thread_group_l1_cache_map,
                                             cpu_id));
        else if (thread_group_shares_l2 && level == 2)
                return cpumask_first(per_cpu(thread_group_l2_cache_map,
                                             cpu_id));
        else if (thread_group_shares_l3 && level == 3)
                return cpumask_first(per_cpu(thread_group_l3_cache_map,
                                             cpu_id));
        return -1;
}

static void do_subsidiary_caches(struct cache *cache, unsigned int cpu_id)
{
        struct device_node *subcache_node;
        int level = cache->level;

        do_subsidiary_caches_debugcheck(cache);

        while ((subcache_node = of_find_next_cache_node(cache->ofnode))) {
                struct cache *subcache;
                int group_id;

                level++;
                group_id = get_group_id(cpu_id, level);
                subcache = cache_lookup_or_instantiate(subcache_node, group_id, level);
                of_node_put(subcache_node);
                if (!subcache)
                        break;

                link_cache_lists(cache, subcache);
                cache = subcache;
        }
}

static struct cache *cache_chain_instantiate(unsigned int cpu_id)
{
        struct device_node *cpu_node;
        struct cache *cpu_cache = NULL;
        int group_id;

        pr_debug("creating cache object(s) for CPU %i\n", cpu_id);

        cpu_node = of_get_cpu_node(cpu_id, NULL);
        WARN_ONCE(!cpu_node, "no OF node found for CPU %i\n", cpu_id);
        if (!cpu_node)
                goto out;

        group_id = get_group_id(cpu_id, 1);

        cpu_cache = cache_lookup_or_instantiate(cpu_node, group_id, 1);
        if (!cpu_cache)
                goto out;

        do_subsidiary_caches(cpu_cache, cpu_id);

        cache_cpu_set(cpu_cache, cpu_id);
out:
        of_node_put(cpu_node);

        return cpu_cache;
}

static struct cache_dir *cacheinfo_create_cache_dir(unsigned int cpu_id)
{
        struct cache_dir *cache_dir;
        struct device *dev;
        struct kobject *kobj = NULL;

        dev = get_cpu_device(cpu_id);
        WARN_ONCE(!dev, "no dev for CPU %i\n", cpu_id);
        if (!dev)
                goto err;

        kobj = kobject_create_and_add("cache", &dev->kobj);
        if (!kobj)
                goto err;

        cache_dir = kzalloc(sizeof(*cache_dir), GFP_KERNEL);
        if (!cache_dir)
                goto err;

        cache_dir->kobj = kobj;

        WARN_ON_ONCE(per_cpu(cache_dir_pcpu, cpu_id) != NULL);

        per_cpu(cache_dir_pcpu, cpu_id) = cache_dir;

        return cache_dir;
err:
        kobject_put(kobj);
        return NULL;
}

static void cache_index_release(struct kobject *kobj)
{
        struct cache_index_dir *index;

        index = kobj_to_cache_index_dir(kobj);

        pr_debug("freeing index directory for L%d %s cache\n",
                 index->cache->level, cache_type_string(index->cache));

        kfree(index);
}

static ssize_t cache_index_show(struct kobject *k, struct attribute *attr, char *buf)
{
        struct kobj_attribute *kobj_attr;

        kobj_attr = container_of(attr, struct kobj_attribute, attr);

        return kobj_attr->show(k, kobj_attr, buf);
}

static struct cache *index_kobj_to_cache(struct kobject *k)
{
        struct cache_index_dir *index;

        index = kobj_to_cache_index_dir(k);

        return index->cache;
}

static ssize_t size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        unsigned int size_kb;
        struct cache *cache;

        cache = index_kobj_to_cache(k);

        if (cache_size_kb(cache, &size_kb))
                return -ENODEV;

        return sprintf(buf, "%uK\n", size_kb);
}

static struct kobj_attribute cache_size_attr =
        __ATTR(size, 0444, size_show, NULL);


static ssize_t line_size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        unsigned int line_size;
        struct cache *cache;

        cache = index_kobj_to_cache(k);

        if (cache_get_line_size(cache, &line_size))
                return -ENODEV;

        return sprintf(buf, "%u\n", line_size);
}

static struct kobj_attribute cache_line_size_attr =
        __ATTR(coherency_line_size, 0444, line_size_show, NULL);

static ssize_t nr_sets_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        unsigned int nr_sets;
        struct cache *cache;

        cache = index_kobj_to_cache(k);

        if (cache_nr_sets(cache, &nr_sets))
                return -ENODEV;

        return sprintf(buf, "%u\n", nr_sets);
}

static struct kobj_attribute cache_nr_sets_attr =
        __ATTR(number_of_sets, 0444, nr_sets_show, NULL);

static ssize_t associativity_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        unsigned int associativity;
        struct cache *cache;

        cache = index_kobj_to_cache(k);

        if (cache_associativity(cache, &associativity))
                return -ENODEV;

        return sprintf(buf, "%u\n", associativity);
}

static struct kobj_attribute cache_assoc_attr =
        __ATTR(ways_of_associativity, 0444, associativity_show, NULL);

static ssize_t type_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        struct cache *cache;

        cache = index_kobj_to_cache(k);

        return sprintf(buf, "%s\n", cache_type_string(cache));
}

static struct kobj_attribute cache_type_attr =
        __ATTR(type, 0444, type_show, NULL);

static ssize_t level_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        struct cache_index_dir *index;
        struct cache *cache;

        index = kobj_to_cache_index_dir(k);
        cache = index->cache;

        return sprintf(buf, "%d\n", cache->level);
}

static struct kobj_attribute cache_level_attr =
        __ATTR(level, 0444, level_show, NULL);

static ssize_t
show_shared_cpumap(struct kobject *k, struct kobj_attribute *attr, char *buf, bool list)
{
        struct cache_index_dir *index;
        struct cache *cache;
        const struct cpumask *mask;

        index = kobj_to_cache_index_dir(k);
        cache = index->cache;

        mask = &cache->shared_cpu_map;

        return cpumap_print_to_pagebuf(list, buf, mask);
}

static ssize_t shared_cpu_map_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        return show_shared_cpumap(k, attr, buf, false);
}

static ssize_t shared_cpu_list_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
{
        return show_shared_cpumap(k, attr, buf, true);
}

static struct kobj_attribute cache_shared_cpu_map_attr =
        __ATTR(shared_cpu_map, 0444, shared_cpu_map_show, NULL);

static struct kobj_attribute cache_shared_cpu_list_attr =
        __ATTR(shared_cpu_list, 0444, shared_cpu_list_show, NULL);

/* Attributes which should always be created -- the kobject/sysfs core
 * does this automatically via kobj_type->default_attrs.  This is the
 * minimum data required to uniquely identify a cache.
 */
static struct attribute *cache_index_default_attrs[] = {
        &cache_type_attr.attr,
        &cache_level_attr.attr,
        &cache_shared_cpu_map_attr.attr,
        &cache_shared_cpu_list_attr.attr,
        NULL,
};

/* Attributes which should be created if the cache device node has the
 * right properties -- see cacheinfo_create_index_opt_attrs
 */
static struct kobj_attribute *cache_index_opt_attrs[] = {
        &cache_size_attr,
        &cache_line_size_attr,
        &cache_nr_sets_attr,
        &cache_assoc_attr,
};

static const struct sysfs_ops cache_index_ops = {
        .show = cache_index_show,
};

static struct kobj_type cache_index_type = {
        .release = cache_index_release,
        .sysfs_ops = &cache_index_ops,
        .default_attrs = cache_index_default_attrs,
};

static void cacheinfo_create_index_opt_attrs(struct cache_index_dir *dir)
{
        const char *cache_type;
        struct cache *cache;
        char *buf;
        int i;

        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!buf)
                return;

        cache = dir->cache;
        cache_type = cache_type_string(cache);

        /* We don't want to create an attribute that can't provide a
         * meaningful value.  Check the return value of each optional
         * attribute's ->show method before registering the
         * attribute.
         */
        for (i = 0; i < ARRAY_SIZE(cache_index_opt_attrs); i++) {
                struct kobj_attribute *attr;
                ssize_t rc;

                attr = cache_index_opt_attrs[i];

                rc = attr->show(&dir->kobj, attr, buf);
                if (rc <= 0) {
                        pr_debug("not creating %s attribute for "
                                 "%pOFP(%s) (rc = %zd)\n",
                                 attr->attr.name, cache->ofnode,
                                 cache_type, rc);
                        continue;
                }
                if (sysfs_create_file(&dir->kobj, &attr->attr))
                        pr_debug("could not create %s attribute for %pOFP(%s)\n",
                                 attr->attr.name, cache->ofnode, cache_type);
        }

        kfree(buf);
}

static void cacheinfo_create_index_dir(struct cache *cache, int index,
                                       struct cache_dir *cache_dir)
{
        struct cache_index_dir *index_dir;
        int rc;

        index_dir = kzalloc(sizeof(*index_dir), GFP_KERNEL);
        if (!index_dir)
                return;

        index_dir->cache = cache;

        rc = kobject_init_and_add(&index_dir->kobj, &cache_index_type,
                                  cache_dir->kobj, "index%d", index);
        if (rc) {
                kobject_put(&index_dir->kobj);
                return;
        }

        index_dir->next = cache_dir->index;
        cache_dir->index = index_dir;

        cacheinfo_create_index_opt_attrs(index_dir);
}

static void cacheinfo_sysfs_populate(unsigned int cpu_id,
                                     struct cache *cache_list)
{
        struct cache_dir *cache_dir;
        struct cache *cache;
        int index = 0;

        cache_dir = cacheinfo_create_cache_dir(cpu_id);
        if (!cache_dir)
                return;

        cache = cache_list;
        while (cache) {
                cacheinfo_create_index_dir(cache, index, cache_dir);
                index++;
                cache = cache->next_local;
        }
}

void cacheinfo_cpu_online(unsigned int cpu_id)
{
        struct cache *cache;

        cache = cache_chain_instantiate(cpu_id);
        if (!cache)
                return;

        cacheinfo_sysfs_populate(cpu_id, cache);
}

/* functions needed to remove cache entry for cpu offline or suspend/resume */

#if (defined(CONFIG_PPC_PSERIES) && defined(CONFIG_SUSPEND)) || \
    defined(CONFIG_HOTPLUG_CPU)

static struct cache *cache_lookup_by_cpu(unsigned int cpu_id)
{
        struct device_node *cpu_node;
        struct cache *cache;
        int group_id;

        cpu_node = of_get_cpu_node(cpu_id, NULL);
        WARN_ONCE(!cpu_node, "no OF node found for CPU %i\n", cpu_id);
        if (!cpu_node)
                return NULL;

        group_id = get_group_id(cpu_id, 1);
        cache = cache_lookup_by_node_group(cpu_node, group_id);
        of_node_put(cpu_node);

        return cache;
}

static void remove_index_dirs(struct cache_dir *cache_dir)
{
        struct cache_index_dir *index;

        index = cache_dir->index;

        while (index) {
                struct cache_index_dir *next;

                next = index->next;
                kobject_put(&index->kobj);
                index = next;
        }
}

static void remove_cache_dir(struct cache_dir *cache_dir)
{
        remove_index_dirs(cache_dir);

        /* Remove cache dir from sysfs */
        kobject_del(cache_dir->kobj);

        kobject_put(cache_dir->kobj);

        kfree(cache_dir);
}

static void cache_cpu_clear(struct cache *cache, int cpu)
{
        while (cache) {
                struct cache *next = cache->next_local;

                WARN_ONCE(!cpumask_test_cpu(cpu, &cache->shared_cpu_map),
                          "CPU %i not accounted in %pOFP(%s)\n",
                          cpu, cache->ofnode,
                          cache_type_string(cache));

                cpumask_clear_cpu(cpu, &cache->shared_cpu_map);

                /* Release the cache object if all the cpus using it
                 * are offline */
                if (cpumask_empty(&cache->shared_cpu_map))
                        release_cache(cache);

                cache = next;
        }
}

void cacheinfo_cpu_offline(unsigned int cpu_id)
{
        struct cache_dir *cache_dir;
        struct cache *cache;

        /* Prevent userspace from seeing inconsistent state - remove
         * the sysfs hierarchy first */
        cache_dir = per_cpu(cache_dir_pcpu, cpu_id);

        /* careful, sysfs population may have failed */
        if (cache_dir)
                remove_cache_dir(cache_dir);

        per_cpu(cache_dir_pcpu, cpu_id) = NULL;

        /* clear the CPU's bit in its cache chain, possibly freeing
         * cache objects */
        cache = cache_lookup_by_cpu(cpu_id);
        if (cache)
                cache_cpu_clear(cache, cpu_id);
}

void cacheinfo_teardown(void)
{
        unsigned int cpu;

        lockdep_assert_cpus_held();

        for_each_online_cpu(cpu)
                cacheinfo_cpu_offline(cpu);
}

void cacheinfo_rebuild(void)
{
        unsigned int cpu;

        lockdep_assert_cpus_held();

        for_each_online_cpu(cpu)
                cacheinfo_cpu_online(cpu);
}

#endif /* (CONFIG_PPC_PSERIES && CONFIG_SUSPEND) || CONFIG_HOTPLUG_CPU */