drivers/firmware/memmap.c

   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/memblock.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  */
  35 struct 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  */
  50 static ssize_t memmap_attr_show(struct kobject *kobj,
  51                                 struct attribute *attr, char *buf);
  52 static ssize_t start_show(struct firmware_map_entry *entry, char *buf);
  53 static ssize_t end_show(struct firmware_map_entry *entry, char *buf);
  54 static ssize_t type_show(struct firmware_map_entry *entry, char *buf);
  55
  56 static struct firmware_map_entry * __meminit
  57 firmware_map_find_entry(u64 start, u64 end, const char *type);
  58
  59 /*
  60  * Static data -----------------------------------------------------------------
  61  */
  62
  63 struct memmap_attribute {
  64         struct attribute attr;
  65         ssize_t (*show)(struct firmware_map_entry *entry, char *buf);
  66 };
  67
  68 static struct memmap_attribute memmap_start_attr = __ATTR_RO(start);
  69 static struct memmap_attribute memmap_end_attr   = __ATTR_RO(end);
  70 static struct memmap_attribute memmap_type_attr  = __ATTR_RO(type);
  71
  72 /*
  73  * These are default attributes that are added for every memmap entry.
  74  */
  75 static struct attribute *def_attrs[] = {
  76         &memmap_start_attr.attr,
  77         &memmap_end_attr.attr,
  78         &memmap_type_attr.attr,
  79         NULL
  80 };
  81
  82 static const struct sysfs_ops memmap_attr_ops = {
  83         .show = memmap_attr_show,
  84 };
  85
  86 /* Firmware memory map entries. */
  87 static LIST_HEAD(map_entries);
  88 static 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  */
  96 static LIST_HEAD(map_entries_bootmem);
  97 static DEFINE_SPINLOCK(map_entries_bootmem_lock);
  98
  99
 100 static inline struct firmware_map_entry *
 101 to_memmap_entry(struct kobject *kobj)
 102 {
 103         return container_of(kobj, struct firmware_map_entry, kobj);
 104 }
 105
 106 static 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
 127 static 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  *
 148  * Return: 0 always
 149  */
 150 static int firmware_map_add_entry(u64 start, u64 end,
 151                                   const char *type,
 152                                   struct firmware_map_entry *entry)
 153 {
 154         BUG_ON(start > end);
 155
 156         entry->start = start;
 157         entry->end = end - 1;
 158         entry->type = type;
 159         INIT_LIST_HEAD(&entry->list);
 160         kobject_init(&entry->kobj, &memmap_ktype);
 161
 162         spin_lock(&map_entries_lock);
 163         list_add_tail(&entry->list, &map_entries);
 164         spin_unlock(&map_entries_lock);
 165
 166         return 0;
 167 }
 168
 169 /**
 170  * firmware_map_remove_entry() - Does the real work to remove a firmware
 171  * memmap entry.
 172  * @entry: removed entry.
 173  *
 174  * The caller must hold map_entries_lock, and release it properly.
 175  */
 176 static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
 177 {
 178         list_del(&entry->list);
 179 }
 180
 181 /*
 182  * Add memmap entry on sysfs
 183  */
 184 static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 185 {
 186         static int map_entries_nr;
 187         static struct kset *mmap_kset;
 188
 189         if (entry->kobj.state_in_sysfs)
 190                 return -EEXIST;
 191
 192         if (!mmap_kset) {
 193                 mmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
 194                 if (!mmap_kset)
 195                         return -ENOMEM;
 196         }
 197
 198         entry->kobj.kset = mmap_kset;
 199         if (kobject_add(&entry->kobj, NULL, "%d", map_entries_nr++))
 200                 kobject_put(&entry->kobj);
 201
 202         return 0;
 203 }
 204
 205 /*
 206  * Remove memmap entry on sysfs
 207  */
 208 static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
 209 {
 210         kobject_put(&entry->kobj);
 211 }
 212
 213 /**
 214  * firmware_map_find_entry_in_list() - Search memmap entry in a given list.
 215  * @start: Start of the memory range.
 216  * @end:   End of the memory range (exclusive).
 217  * @type:  Type of the memory range.
 218  * @list:  In which to find the entry.
 219  *
 220  * This function is to find the memmap entey of a given memory range in a
 221  * given list. The caller must hold map_entries_lock, and must not release
 222  * the lock until the processing of the returned entry has completed.
 223  *
 224  * Return: Pointer to the entry to be found on success, or NULL on failure.
 225  */
 226 static struct firmware_map_entry * __meminit
 227 firmware_map_find_entry_in_list(u64 start, u64 end, const char *type,
 228                                 struct list_head *list)
 229 {
 230         struct firmware_map_entry *entry;
 231
 232         list_for_each_entry(entry, list, list)
 233                 if ((entry->start == start) && (entry->end == end) &&
 234                     (!strcmp(entry->type, type))) {
 235                         return entry;
 236                 }
 237
 238         return NULL;
 239 }
 240
 241 /**
 242  * firmware_map_find_entry() - Search memmap entry in map_entries.
 243  * @start: Start of the memory range.
 244  * @end:   End of the memory range (exclusive).
 245  * @type:  Type of the memory range.
 246  *
 247  * This function is to find the memmap entey of a given memory range.
 248  * The caller must hold map_entries_lock, and must not release the lock
 249  * until the processing of the returned entry has completed.
 250  *
 251  * Return: Pointer to the entry to be found on success, or NULL on failure.
 252  */
 253 static struct firmware_map_entry * __meminit
 254 firmware_map_find_entry(u64 start, u64 end, const char *type)
 255 {
 256         return firmware_map_find_entry_in_list(start, end, type, &map_entries);
 257 }
 258
 259 /**
 260  * firmware_map_find_entry_bootmem() - Search memmap entry in map_entries_bootmem.
 261  * @start: Start of the memory range.
 262  * @end:   End of the memory range (exclusive).
 263  * @type:  Type of the memory range.
 264  *
 265  * This function is similar to firmware_map_find_entry except that it find the
 266  * given entry in map_entries_bootmem.
 267  *
 268  * Return: Pointer to the entry to be found on success, or NULL on failure.
 269  */
 270 static struct firmware_map_entry * __meminit
 271 firmware_map_find_entry_bootmem(u64 start, u64 end, const char *type)
 272 {
 273         return firmware_map_find_entry_in_list(start, end, type,
 274                                                &map_entries_bootmem);
 275 }
 276
 277 /**
 278  * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
 279  * memory hotplug.
 280  * @start: Start of the memory range.
 281  * @end:   End of the memory range (exclusive)
 282  * @type:  Type of the memory range.
 283  *
 284  * Adds a firmware mapping entry. This function is for memory hotplug, it is
 285  * similar to function firmware_map_add_early(). The only difference is that
 286  * it will create the syfs entry dynamically.
 287  *
 288  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
 289  */
 290 int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
 291 {
 292         struct firmware_map_entry *entry;
 293
 294         entry = firmware_map_find_entry(start, end - 1, type);
 295         if (entry)
 296                 return 0;
 297
 298         entry = firmware_map_find_entry_bootmem(start, end - 1, type);
 299         if (!entry) {
 300                 entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
 301                 if (!entry)
 302                         return -ENOMEM;
 303         } else {
 304                 /* Reuse storage allocated by bootmem. */
 305                 spin_lock(&map_entries_bootmem_lock);
 306                 list_del(&entry->list);
 307                 spin_unlock(&map_entries_bootmem_lock);
 308
 309                 memset(entry, 0, sizeof(*entry));
 310         }
 311
 312         firmware_map_add_entry(start, end, type, entry);
 313         /* create the memmap entry */
 314         add_sysfs_fw_map_entry(entry);
 315
 316         return 0;
 317 }
 318
 319 /**
 320  * firmware_map_add_early() - Adds a firmware mapping entry.
 321  * @start: Start of the memory range.
 322  * @end:   End of the memory range.
 323  * @type:  Type of the memory range.
 324  *
 325  * Adds a firmware mapping entry. This function uses the bootmem allocator
 326  * for memory allocation.
 327  *
 328  * That function must be called before late_initcall.
 329  *
 330  * Return: 0 on success, or -ENOMEM if no memory could be allocated.
 331  */
 332 int __init firmware_map_add_early(u64 start, u64 end, const char *type)
 333 {
 334         struct firmware_map_entry *entry;
 335
 336         entry = memblock_alloc(sizeof(struct firmware_map_entry),
 337                                SMP_CACHE_BYTES);
 338         if (WARN_ON(!entry))
 339                 return -ENOMEM;
 340
 341         return firmware_map_add_entry(start, end, type, entry);
 342 }
 343
 344 /**
 345  * firmware_map_remove() - remove a firmware mapping entry
 346  * @start: Start of the memory range.
 347  * @end:   End of the memory range.
 348  * @type:  Type of the memory range.
 349  *
 350  * removes a firmware mapping entry.
 351  *
 352  * Return: 0 on success, or -EINVAL if no entry.
 353  */
 354 int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
 355 {
 356         struct firmware_map_entry *entry;
 357
 358         spin_lock(&map_entries_lock);
 359         entry = firmware_map_find_entry(start, end - 1, type);
 360         if (!entry) {
 361                 spin_unlock(&map_entries_lock);
 362                 return -EINVAL;
 363         }
 364
 365         firmware_map_remove_entry(entry);
 366         spin_unlock(&map_entries_lock);
 367
 368         /* remove the memmap entry */
 369         remove_sysfs_fw_map_entry(entry);
 370
 371         return 0;
 372 }
 373
 374 /*
 375  * Sysfs functions -------------------------------------------------------------
 376  */
 377
 378 static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
 379 {
 380         return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 381                 (unsigned long long)entry->start);
 382 }
 383
 384 static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
 385 {
 386         return snprintf(buf, PAGE_SIZE, "0x%llx\n",
 387                 (unsigned long long)entry->end);
 388 }
 389
 390 static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
 391 {
 392         return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
 393 }
 394
 395 static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
 396 {
 397         return container_of(attr, struct memmap_attribute, attr);
 398 }
 399
 400 static ssize_t memmap_attr_show(struct kobject *kobj,
 401                                 struct attribute *attr, char *buf)
 402 {
 403         struct firmware_map_entry *entry = to_memmap_entry(kobj);
 404         struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
 405
 406         return memmap_attr->show(entry, buf);
 407 }
 408
 409 /*
 410  * Initialises stuff and adds the entries in the map_entries list to
 411  * sysfs. Important is that firmware_map_add() and firmware_map_add_early()
 412  * must be called before late_initcall. That's just because that function
 413  * is called as late_initcall() function, which means that if you call
 414  * firmware_map_add() or firmware_map_add_early() afterwards, the entries
 415  * are not added to sysfs.
 416  */
 417 static int __init firmware_memmap_init(void)
 418 {
 419         struct firmware_map_entry *entry;
 420
 421         list_for_each_entry(entry, &map_entries, list)
 422                 add_sysfs_fw_map_entry(entry);
 423
 424         return 0;
 425 }
 426 late_initcall(firmware_memmap_init);
 427