linux/drivers/firmware/memmap.c
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   1/*
   2 * linux/drivers/firmware/memmap.c
   3 *  Copyright (C) 2008 SUSE LINUX Products GmbH
   4 *  by Bernhard Walle <bernhard.walle@gmx.de>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License v2.0 as published by
   8 * the Free Software Foundation
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 */
  16
  17#include <linux/string.h>
  18#include <linux/firmware-map.h>
  19#include <linux/kernel.h>
  20#include <linux/module.h>
  21#include <linux/types.h>
  22#include <linux/bootmem.h>
  23#include <linux/slab.h>
  24#include <linux/mm.h>
  25
  26/*
  27 * Data types ------------------------------------------------------------------
  28 */
  29
  30/*
  31 * Firmware map entry. Because firmware memory maps are flat and not
  32 * hierarchical, it's ok to organise them in a linked list. No parent
  33 * information is necessary as for the resource tree.
  34 */
  35struct firmware_map_entry {
  36        /*
  37         * start and end must be u64 rather than resource_size_t, because e820
  38         * resources can lie at addresses above 4G.
  39         */
  40        u64                     start;  /* start of the memory range */
  41        u64                     end;    /* end of the memory range (incl.) */
  42        const char              *type;  /* type of the memory range */
  43        struct list_head        list;   /* entry for the linked list */
  44        struct kobject          kobj;   /* kobject for each entry */
  45};
  46
  47/*
  48 * Forward declarations --------------------------------------------------------
  49 */
  50static ssize_t memmap_attr_show(struct kobject *kobj,
  51                                struct attribute *attr, char *buf);
  52static ssize_t start_show(struct firmware_map_entry *entry, char *buf);
  53static ssize_t end_show(struct firmware_map_entry *entry, char *buf);
  54static ssize_t type_show(struct firmware_map_entry *entry, char *buf);
  55
  56static struct firmware_map_entry * __meminit
  57firmware_map_find_entry(u64 start, u64 end, const char *type);
  58
  59/*
  60 * Static data -----------------------------------------------------------------
  61 */
  62
  63struct memmap_attribute {
  64        struct attribute attr;
  65        ssize_t (*show)(struct firmware_map_entry *entry, char *buf);
  66};
  67
  68static struct memmap_attribute memmap_start_attr = __ATTR_RO(start);
  69static struct memmap_attribute memmap_end_attr   = __ATTR_RO(end);
  70static struct memmap_attribute memmap_type_attr  = __ATTR_RO(type);
  71
  72/*
  73 * These are default attributes that are added for every memmap entry.
  74 */
  75static struct attribute *def_attrs[] = {
  76        &memmap_start_attr.attr,
  77        &memmap_end_attr.attr,
  78        &memmap_type_attr.attr,
  79        NULL
  80};
  81
  82static const struct sysfs_ops memmap_attr_ops = {
  83        .show = memmap_attr_show,
  84};
  85
  86/* Firmware memory map entries. */
  87static LIST_HEAD(map_entries);
  88static DEFINE_SPINLOCK(map_entries_lock);
  89
  90/*
  91 * For memory hotplug, there is no way to free memory map entries allocated
  92 * by boot mem after the system is up. So when we hot-remove memory whose
  93 * map entry is allocated by bootmem, we need to remember the storage and
  94 * reuse it when the memory is hot-added again.
  95 */
  96static LIST_HEAD(map_entries_bootmem);
  97static DEFINE_SPINLOCK(map_entries_bootmem_lock);
  98
  99
 100static inline struct firmware_map_entry *
 101to_memmap_entry(struct kobject *kobj)
 102{
 103        return container_of(kobj, struct firmware_map_entry, kobj);
 104}
 105
 106static void __meminit release_firmware_map_entry(struct kobject *kobj)
 107{
 108        struct firmware_map_entry *entry = to_memmap_entry(kobj);
 109
 110        if (PageReserved(virt_to_page(entry))) {
 111                /*
 112                 * Remember the storage allocated by bootmem, and reuse it when
 113                 * the memory is hot-added again. The entry will be added to
 114                 * map_entries_bootmem here, and deleted from &map_entries in
 115                 * firmware_map_remove_entry().
 116                 */
 117                spin_lock(&map_entries_bootmem_lock);
 118                list_add(&entry->list, &map_entries_bootmem);
 119                spin_unlock(&map_entries_bootmem_lock);
 120
 121                return;
 122        }
 123
 124        kfree(entry);
 125}
 126
 127static struct kobj_type __refdata memmap_ktype = {
 128        .release        = release_firmware_map_entry,
 129        .sysfs_ops      = &memmap_attr_ops,
 130        .default_attrs  = def_attrs,
 131};
 132
 133/*
 134 * Registration functions ------------------------------------------------------
 135 */
 136
 137/**
 138 * firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
 139 * @start: Start of the memory range.
 140 * @end:   End of the memory range (exclusive).
 141 * @type:  Type of the memory range.
 142 * @entry: Pre-allocated (either kmalloc() or bootmem allocator), uninitialised
 143 *         entry.
 144 *
 145 * Common implementation of firmware_map_add() and firmware_map_add_early()
 146 * which expects a pre-allocated struct firmware_map_entry.
 147 **/
 148static int firmware_map_add_entry(u64 start, u64 end,
 149                                  const char *type,
 150                                  struct firmware_map_entry *entry)
 151{
 152        BUG_ON(start > end);
 153
 154        entry->start = start;
 155        entry->end = end - 1;
 156        entry->type = type;
 157        INIT_LIST_HEAD(&entry->list);
 158        kobject_init(&entry->kobj, &memmap_ktype);
 159
 160        spin_lock(&map_entries_lock);
 161        list_add_tail(&entry->list, &map_entries);
 162        spin_unlock(&map_entries_lock);
 163
 164        return 0;
 165}
 166
 167/**
 168 * firmware_map_remove_entry() - Does the real work to remove a firmware
 169 * memmap entry.
 170 * @entry: removed entry.
 171 *
 172 * The caller must hold map_entries_lock, and release it properly.
 173 **/
 174static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
 175{
 176        list_del(&entry->list);
 177}
 178
 179/*
 180 * Add memmap entry on sysfs
 181 */
 182static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 183{
 184        static int map_entries_nr;
 185        static struct kset *mmap_kset;
 186
 187        if (!mmap_kset) {
 188                mmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
 189                if (!mmap_kset)
 190                        return -ENOMEM;
 191        }
 192
 193        entry->kobj.kset = mmap_kset;
 194        if (kobject_add(&entry->kobj, NULL, "%d", map_entries_nr++))
 195                kobject_put(&entry->kobj);
 196
 197        return 0;
 198}
 199
 200/*
 201 * Remove memmap entry on sysfs
 202 */
 203static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 204{
 205        kobject_put(&entry->kobj);
 206}
 207
 208/*
 209 * firmware_map_find_entry_in_list() - Search memmap entry in a given list.
 210 * @start: Start of the memory range.
 211 * @end:   End of the memory range (exclusive).
 212 * @type:  Type of the memory range.
 213 * @list:  In which to find the entry.
 214 *
 215 * This function is to find the memmap entey of a given memory range in a
 216 * given list. The caller must hold map_entries_lock, and must not release
 217 * the lock until the processing of the returned entry has completed.
 218 *
 219 * Return: Pointer to the entry to be found on success, or NULL on failure.
 220 */
 221static struct firmware_map_entry * __meminit
 222firmware_map_find_entry_in_list(u64 start, u64 end, const char *type,
 223                                struct list_head *list)
 224{
 225        struct firmware_map_entry *entry;
 226
 227        list_for_each_entry(entry, list, list)
 228                if ((entry->start == start) && (entry->end == end) &&
 229                    (!strcmp(entry->type, type))) {
 230                        return entry;
 231                }
 232
 233        return NULL;
 234}
 235
 236/*
 237 * firmware_map_find_entry() - Search memmap entry in map_entries.
 238 * @start: Start of the memory range.
 239 * @end:   End of the memory range (exclusive).
 240 * @type:  Type of the memory range.
 241 *
 242 * This function is to find the memmap entey of a given memory range.
 243 * The caller must hold map_entries_lock, and must not release the lock
 244 * until the processing of the returned entry has completed.
 245 *
 246 * Return: Pointer to the entry to be found on success, or NULL on failure.
 247 */
 248static struct firmware_map_entry * __meminit
 249firmware_map_find_entry(u64 start, u64 end, const char *type)
 250{
 251        return firmware_map_find_entry_in_list(start, end, type, &map_entries);
 252}
 253
 254/*
 255 * firmware_map_find_entry_bootmem() - Search memmap entry in map_entries_bootmem.
 256 * @start: Start of the memory range.
 257 * @end:   End of the memory range (exclusive).
 258 * @type:  Type of the memory range.
 259 *
 260 * This function is similar to firmware_map_find_entry except that it find the
 261 * given entry in map_entries_bootmem.
 262 *
 263 * Return: Pointer to the entry to be found on success, or NULL on failure.
 264 */
 265static struct firmware_map_entry * __meminit
 266firmware_map_find_entry_bootmem(u64 start, u64 end, const char *type)
 267{
 268        return firmware_map_find_entry_in_list(start, end, type,
 269                                               &map_entries_bootmem);
 270}
 271
 272/**
 273 * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
 274 * memory hotplug.
 275 * @start: Start of the memory range.
 276 * @end:   End of the memory range (exclusive)
 277 * @type:  Type of the memory range.
 278 *
 279 * Adds a firmware mapping entry. This function is for memory hotplug, it is
 280 * similar to function firmware_map_add_early(). The only difference is that
 281 * it will create the syfs entry dynamically.
 282 *
 283 * Returns 0 on success, or -ENOMEM if no memory could be allocated.
 284 **/
 285int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
 286{
 287        struct firmware_map_entry *entry;
 288
 289        entry = firmware_map_find_entry_bootmem(start, end, type);
 290        if (!entry) {
 291                entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
 292                if (!entry)
 293                        return -ENOMEM;
 294        } else {
 295                /* Reuse storage allocated by bootmem. */
 296                spin_lock(&map_entries_bootmem_lock);
 297                list_del(&entry->list);
 298                spin_unlock(&map_entries_bootmem_lock);
 299
 300                memset(entry, 0, sizeof(*entry));
 301        }
 302
 303        firmware_map_add_entry(start, end, type, entry);
 304        /* create the memmap entry */
 305        add_sysfs_fw_map_entry(entry);
 306
 307        return 0;
 308}
 309
 310/**
 311 * firmware_map_add_early() - Adds a firmware mapping entry.
 312 * @start: Start of the memory range.
 313 * @end:   End of the memory range.
 314 * @type:  Type of the memory range.
 315 *
 316 * Adds a firmware mapping entry. This function uses the bootmem allocator
 317 * for memory allocation.
 318 *
 319 * That function must be called before late_initcall.
 320 *
 321 * Returns 0 on success, or -ENOMEM if no memory could be allocated.
 322 **/
 323int __init firmware_map_add_early(u64 start, u64 end, const char *type)
 324{
 325        struct firmware_map_entry *entry;
 326
 327        entry = alloc_bootmem(sizeof(struct firmware_map_entry));
 328        if (WARN_ON(!entry))
 329                return -ENOMEM;
 330
 331        return firmware_map_add_entry(start, end, type, entry);
 332}
 333
 334/**
 335 * firmware_map_remove() - remove a firmware mapping entry
 336 * @start: Start of the memory range.
 337 * @end:   End of the memory range.
 338 * @type:  Type of the memory range.
 339 *
 340 * removes a firmware mapping entry.
 341 *
 342 * Returns 0 on success, or -EINVAL if no entry.
 343 **/
 344int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
 345{
 346        struct firmware_map_entry *entry;
 347
 348        spin_lock(&map_entries_lock);
 349        entry = firmware_map_find_entry(start, end - 1, type);
 350        if (!entry) {
 351                spin_unlock(&map_entries_lock);
 352                return -EINVAL;
 353        }
 354
 355        firmware_map_remove_entry(entry);
 356        spin_unlock(&map_entries_lock);
 357
 358        /* remove the memmap entry */
 359        remove_sysfs_fw_map_entry(entry);
 360
 361        return 0;
 362}
 363
 364/*
 365 * Sysfs functions -------------------------------------------------------------
 366 */
 367
 368static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
 369{
 370        return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 371                (unsigned long long)entry->start);
 372}
 373
 374static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
 375{
 376        return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 377                (unsigned long long)entry->end);
 378}
 379
 380static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
 381{
 382        return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
 383}
 384
 385static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
 386{
 387        return container_of(attr, struct memmap_attribute, attr);
 388}
 389
 390static ssize_t memmap_attr_show(struct kobject *kobj,
 391                                struct attribute *attr, char *buf)
 392{
 393        struct firmware_map_entry *entry = to_memmap_entry(kobj);
 394        struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
 395
 396        return memmap_attr->show(entry, buf);
 397}
 398
 399/*
 400 * Initialises stuff and adds the entries in the map_entries list to
 401 * sysfs. Important is that firmware_map_add() and firmware_map_add_early()
 402 * must be called before late_initcall. That's just because that function
 403 * is called as late_initcall() function, which means that if you call
 404 * firmware_map_add() or firmware_map_add_early() afterwards, the entries
 405 * are not added to sysfs.
 406 */
 407static int __init firmware_memmap_init(void)
 408{
 409        struct firmware_map_entry *entry;
 410
 411        list_for_each_entry(entry, &map_entries, list)
 412                add_sysfs_fw_map_entry(entry);
 413
 414        return 0;
 415}
 416late_initcall(firmware_memmap_init);
 417
 418
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