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                if (firmware_map_find_entry(entry->start, entry->end,
 118                    entry->type)) {
 119                        spin_lock(&map_entries_bootmem_lock);
 120                        list_add(&entry->list, &map_entries_bootmem);
 121                        spin_unlock(&map_entries_bootmem_lock);
 122                }
 123
 124                return;
 125        }
 126
 127        kfree(entry);
 128}
 129
 130static struct kobj_type __refdata memmap_ktype = {
 131        .release        = release_firmware_map_entry,
 132        .sysfs_ops      = &memmap_attr_ops,
 133        .default_attrs  = def_attrs,
 134};
 135
 136/*
 137 * Registration functions ------------------------------------------------------
 138 */
 139
 140/**
 141 * firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
 142 * @start: Start of the memory range.
 143 * @end:   End of the memory range (exclusive).
 144 * @type:  Type of the memory range.
 145 * @entry: Pre-allocated (either kmalloc() or bootmem allocator), uninitialised
 146 *         entry.
 147 *
 148 * Common implementation of firmware_map_add() and firmware_map_add_early()
 149 * which expects a pre-allocated struct firmware_map_entry.
 150 **/
 151static int firmware_map_add_entry(u64 start, u64 end,
 152                                  const char *type,
 153                                  struct firmware_map_entry *entry)
 154{
 155        BUG_ON(start > end);
 156
 157        entry->start = start;
 158        entry->end = end - 1;
 159        entry->type = type;
 160        INIT_LIST_HEAD(&entry->list);
 161        kobject_init(&entry->kobj, &memmap_ktype);
 162
 163        spin_lock(&map_entries_lock);
 164        list_add_tail(&entry->list, &map_entries);
 165        spin_unlock(&map_entries_lock);
 166
 167        return 0;
 168}
 169
 170/**
 171 * firmware_map_remove_entry() - Does the real work to remove a firmware
 172 * memmap entry.
 173 * @entry: removed entry.
 174 *
 175 * The caller must hold map_entries_lock, and release it properly.
 176 **/
 177static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
 178{
 179        list_del(&entry->list);
 180}
 181
 182/*
 183 * Add memmap entry on sysfs
 184 */
 185static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 186{
 187        static int map_entries_nr;
 188        static struct kset *mmap_kset;
 189
 190        if (!mmap_kset) {
 191                mmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
 192                if (!mmap_kset)
 193                        return -ENOMEM;
 194        }
 195
 196        entry->kobj.kset = mmap_kset;
 197        if (kobject_add(&entry->kobj, NULL, "%d", map_entries_nr++))
 198                kobject_put(&entry->kobj);
 199
 200        return 0;
 201}
 202
 203/*
 204 * Remove memmap entry on sysfs
 205 */
 206static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 207{
 208        kobject_put(&entry->kobj);
 209}
 210
 211/*
 212 * firmware_map_find_entry_in_list() - Search memmap entry in a given list.
 213 * @start: Start of the memory range.
 214 * @end:   End of the memory range (exclusive).
 215 * @type:  Type of the memory range.
 216 * @list:  In which to find the entry.
 217 *
 218 * This function is to find the memmap entey of a given memory range in a
 219 * given list. The caller must hold map_entries_lock, and must not release
 220 * the lock until the processing of the returned entry has completed.
 221 *
 222 * Return: Pointer to the entry to be found on success, or NULL on failure.
 223 */
 224static struct firmware_map_entry * __meminit
 225firmware_map_find_entry_in_list(u64 start, u64 end, const char *type,
 226                                struct list_head *list)
 227{
 228        struct firmware_map_entry *entry;
 229
 230        list_for_each_entry(entry, list, list)
 231                if ((entry->start == start) && (entry->end == end) &&
 232                    (!strcmp(entry->type, type))) {
 233                        return entry;
 234                }
 235
 236        return NULL;
 237}
 238
 239/*
 240 * firmware_map_find_entry() - Search memmap entry in map_entries.
 241 * @start: Start of the memory range.
 242 * @end:   End of the memory range (exclusive).
 243 * @type:  Type of the memory range.
 244 *
 245 * This function is to find the memmap entey of a given memory range.
 246 * The caller must hold map_entries_lock, and must not release the lock
 247 * until the processing of the returned entry has completed.
 248 *
 249 * Return: Pointer to the entry to be found on success, or NULL on failure.
 250 */
 251static struct firmware_map_entry * __meminit
 252firmware_map_find_entry(u64 start, u64 end, const char *type)
 253{
 254        return firmware_map_find_entry_in_list(start, end, type, &map_entries);
 255}
 256
 257/*
 258 * firmware_map_find_entry_bootmem() - Search memmap entry in map_entries_bootmem.
 259 * @start: Start of the memory range.
 260 * @end:   End of the memory range (exclusive).
 261 * @type:  Type of the memory range.
 262 *
 263 * This function is similar to firmware_map_find_entry except that it find the
 264 * given entry in map_entries_bootmem.
 265 *
 266 * Return: Pointer to the entry to be found on success, or NULL on failure.
 267 */
 268static struct firmware_map_entry * __meminit
 269firmware_map_find_entry_bootmem(u64 start, u64 end, const char *type)
 270{
 271        return firmware_map_find_entry_in_list(start, end, type,
 272                                               &map_entries_bootmem);
 273}
 274
 275/**
 276 * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
 277 * memory hotplug.
 278 * @start: Start of the memory range.
 279 * @end:   End of the memory range (exclusive)
 280 * @type:  Type of the memory range.
 281 *
 282 * Adds a firmware mapping entry. This function is for memory hotplug, it is
 283 * similar to function firmware_map_add_early(). The only difference is that
 284 * it will create the syfs entry dynamically.
 285 *
 286 * Returns 0 on success, or -ENOMEM if no memory could be allocated.
 287 **/
 288int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
 289{
 290        struct firmware_map_entry *entry;
 291
 292        entry = firmware_map_find_entry_bootmem(start, end, type);
 293        if (!entry) {
 294                entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
 295                if (!entry)
 296                        return -ENOMEM;
 297        } else {
 298                /* Reuse storage allocated by bootmem. */
 299                spin_lock(&map_entries_bootmem_lock);
 300                list_del(&entry->list);
 301                spin_unlock(&map_entries_bootmem_lock);
 302
 303                memset(entry, 0, sizeof(*entry));
 304        }
 305
 306        firmware_map_add_entry(start, end, type, entry);
 307        /* create the memmap entry */
 308        add_sysfs_fw_map_entry(entry);
 309
 310        return 0;
 311}
 312
 313/**
 314 * firmware_map_add_early() - Adds a firmware mapping entry.
 315 * @start: Start of the memory range.
 316 * @end:   End of the memory range.
 317 * @type:  Type of the memory range.
 318 *
 319 * Adds a firmware mapping entry. This function uses the bootmem allocator
 320 * for memory allocation.
 321 *
 322 * That function must be called before late_initcall.
 323 *
 324 * Returns 0 on success, or -ENOMEM if no memory could be allocated.
 325 **/
 326int __init firmware_map_add_early(u64 start, u64 end, const char *type)
 327{
 328        struct firmware_map_entry *entry;
 329
 330        entry = alloc_bootmem(sizeof(struct firmware_map_entry));
 331        if (WARN_ON(!entry))
 332                return -ENOMEM;
 333
 334        return firmware_map_add_entry(start, end, type, entry);
 335}
 336
 337/**
 338 * firmware_map_remove() - remove a firmware mapping entry
 339 * @start: Start of the memory range.
 340 * @end:   End of the memory range.
 341 * @type:  Type of the memory range.
 342 *
 343 * removes a firmware mapping entry.
 344 *
 345 * Returns 0 on success, or -EINVAL if no entry.
 346 **/
 347int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
 348{
 349        struct firmware_map_entry *entry;
 350
 351        spin_lock(&map_entries_lock);
 352        entry = firmware_map_find_entry(start, end - 1, type);
 353        if (!entry) {
 354                spin_unlock(&map_entries_lock);
 355                return -EINVAL;
 356        }
 357
 358        firmware_map_remove_entry(entry);
 359        spin_unlock(&map_entries_lock);
 360
 361        /* remove the memmap entry */
 362        remove_sysfs_fw_map_entry(entry);
 363
 364        return 0;
 365}
 366
 367/*
 368 * Sysfs functions -------------------------------------------------------------
 369 */
 370
 371static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
 372{
 373        return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 374                (unsigned long long)entry->start);
 375}
 376
 377static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
 378{
 379        return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 380                (unsigned long long)entry->end);
 381}
 382
 383static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
 384{
 385        return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
 386}
 387
 388static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
 389{
 390        return container_of(attr, struct memmap_attribute, attr);
 391}
 392
 393static ssize_t memmap_attr_show(struct kobject *kobj,
 394                                struct attribute *attr, char *buf)
 395{
 396        struct firmware_map_entry *entry = to_memmap_entry(kobj);
 397        struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
 398
 399        return memmap_attr->show(entry, buf);
 400}
 401
 402/*
 403 * Initialises stuff and adds the entries in the map_entries list to
 404 * sysfs. Important is that firmware_map_add() and firmware_map_add_early()
 405 * must be called before late_initcall. That's just because that function
 406 * is called as late_initcall() function, which means that if you call
 407 * firmware_map_add() or firmware_map_add_early() afterwards, the entries
 408 * are not added to sysfs.
 409 */
 410static int __init firmware_memmap_init(void)
 411{
 412        struct firmware_map_entry *entry;
 413
 414        list_for_each_entry(entry, &map_entries, list)
 415                add_sysfs_fw_map_entry(entry);
 416
 417        return 0;
 418}
 419late_initcall(firmware_memmap_init);
 420
 421
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