drivers/firmware/qemu_fw_cfg.c

   1 /*
   2  * drivers/firmware/qemu_fw_cfg.c
   3  *
   4  * Copyright 2015 Carnegie Mellon University
   5  *
   6  * Expose entries from QEMU's firmware configuration (fw_cfg) device in
   7  * sysfs (read-only, under "/sys/firmware/qemu_fw_cfg/...").
   8  *
   9  * The fw_cfg device may be instantiated via either an ACPI node (on x86
  10  * and select subsets of aarch64), a Device Tree node (on arm), or using
  11  * a kernel module (or command line) parameter with the following syntax:
  12  *
  13  *      [qemu_fw_cfg.]ioport=<size>@<base>[:<ctrl_off>:<data_off>[:<dma_off>]]
  14  * or
  15  *      [qemu_fw_cfg.]mmio=<size>@<base>[:<ctrl_off>:<data_off>[:<dma_off>]]
  16  *
  17  * where:
  18  *      <size>     := size of ioport or mmio range
  19  *      <base>     := physical base address of ioport or mmio range
  20  *      <ctrl_off> := (optional) offset of control register
  21  *      <data_off> := (optional) offset of data register
  22  *      <dma_off> := (optional) offset of dma register
  23  *
  24  * e.g.:
  25  *      qemu_fw_cfg.ioport=12@0x510:0:1:4       (the default on x86)
  26  * or
  27  *      qemu_fw_cfg.mmio=16@0x9020000:8:0:16    (the default on arm)
  28  */
  29
  30 #include <linux/module.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/acpi.h>
  33 #include <linux/slab.h>
  34 #include <linux/io.h>
  35 #include <linux/ioport.h>
  36 #include <uapi/linux/qemu_fw_cfg.h>
  37 #include <linux/delay.h>
  38 #include <linux/crash_dump.h>
  39 #include <linux/crash_core.h>
  40
  41 MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
  42 MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
  43 MODULE_LICENSE("GPL");
  44
  45 /* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
  46 static u32 fw_cfg_rev;
  47
  48 /* fw_cfg device i/o register addresses */
  49 static bool fw_cfg_is_mmio;
  50 static phys_addr_t fw_cfg_p_base;
  51 static resource_size_t fw_cfg_p_size;
  52 static void __iomem *fw_cfg_dev_base;
  53 static void __iomem *fw_cfg_reg_ctrl;
  54 static void __iomem *fw_cfg_reg_data;
  55 static void __iomem *fw_cfg_reg_dma;
  56
  57 /* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */
  58 static DEFINE_MUTEX(fw_cfg_dev_lock);
  59
  60 /* pick appropriate endianness for selector key */
  61 static void fw_cfg_sel_endianness(u16 key)
  62 {
  63         if (fw_cfg_is_mmio)
  64                 iowrite16be(key, fw_cfg_reg_ctrl);
  65         else
  66                 iowrite16(key, fw_cfg_reg_ctrl);
  67 }
  68
  69 #ifdef CONFIG_CRASH_CORE
  70 static inline bool fw_cfg_dma_enabled(void)
  71 {
  72         return (fw_cfg_rev & FW_CFG_VERSION_DMA) && fw_cfg_reg_dma;
  73 }
  74
  75 /* qemu fw_cfg device is sync today, but spec says it may become async */
  76 static void fw_cfg_wait_for_control(struct fw_cfg_dma_access *d)
  77 {
  78         for (;;) {
  79                 u32 ctrl = be32_to_cpu(READ_ONCE(d->control));
  80
  81                 /* do not reorder the read to d->control */
  82                 rmb();
  83                 if ((ctrl & ~FW_CFG_DMA_CTL_ERROR) == 0)
  84                         return;
  85
  86                 cpu_relax();
  87         }
  88 }
  89
  90 static ssize_t fw_cfg_dma_transfer(void *address, u32 length, u32 control)
  91 {
  92         phys_addr_t dma;
  93         struct fw_cfg_dma_access *d = NULL;
  94         ssize_t ret = length;
  95
  96         d = kmalloc(sizeof(*d), GFP_KERNEL);
  97         if (!d) {
  98                 ret = -ENOMEM;
  99                 goto end;
 100         }
 101
 102         /* fw_cfg device does not need IOMMU protection, so use physical addresses */
 103         *d = (struct fw_cfg_dma_access) {
 104                 .address = cpu_to_be64(address ? virt_to_phys(address) : 0),
 105                 .length = cpu_to_be32(length),
 106                 .control = cpu_to_be32(control)
 107         };
 108
 109         dma = virt_to_phys(d);
 110
 111         iowrite32be((u64)dma >> 32, fw_cfg_reg_dma);
 112         /* force memory to sync before notifying device via MMIO */
 113         wmb();
 114         iowrite32be(dma, fw_cfg_reg_dma + 4);
 115
 116         fw_cfg_wait_for_control(d);
 117
 118         if (be32_to_cpu(READ_ONCE(d->control)) & FW_CFG_DMA_CTL_ERROR) {
 119                 ret = -EIO;
 120         }
 121
 122 end:
 123         kfree(d);
 124
 125         return ret;
 126 }
 127 #endif
 128
 129 /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
 130 static ssize_t fw_cfg_read_blob(u16 key,
 131                                 void *buf, loff_t pos, size_t count)
 132 {
 133         u32 glk = -1U;
 134         acpi_status status;
 135
 136         /* If we have ACPI, ensure mutual exclusion against any potential
 137          * device access by the firmware, e.g. via AML methods:
 138          */
 139         status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
 140         if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
 141                 /* Should never get here */
 142                 WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
 143                 memset(buf, 0, count);
 144                 return -EINVAL;
 145         }
 146
 147         mutex_lock(&fw_cfg_dev_lock);
 148         fw_cfg_sel_endianness(key);
 149         while (pos-- > 0)
 150                 ioread8(fw_cfg_reg_data);
 151         ioread8_rep(fw_cfg_reg_data, buf, count);
 152         mutex_unlock(&fw_cfg_dev_lock);
 153
 154         acpi_release_global_lock(glk);
 155         return count;
 156 }
 157
 158 #ifdef CONFIG_CRASH_CORE
 159 /* write chunk of given fw_cfg blob (caller responsible for sanity-check) */
 160 static ssize_t fw_cfg_write_blob(u16 key,
 161                                  void *buf, loff_t pos, size_t count)
 162 {
 163         u32 glk = -1U;
 164         acpi_status status;
 165         ssize_t ret = count;
 166
 167         /* If we have ACPI, ensure mutual exclusion against any potential
 168          * device access by the firmware, e.g. via AML methods:
 169          */
 170         status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
 171         if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
 172                 /* Should never get here */
 173                 WARN(1, "%s: Failed to lock ACPI!\n", __func__);
 174                 return -EINVAL;
 175         }
 176
 177         mutex_lock(&fw_cfg_dev_lock);
 178         if (pos == 0) {
 179                 ret = fw_cfg_dma_transfer(buf, count, key << 16
 180                                           | FW_CFG_DMA_CTL_SELECT
 181                                           | FW_CFG_DMA_CTL_WRITE);
 182         } else {
 183                 fw_cfg_sel_endianness(key);
 184                 ret = fw_cfg_dma_transfer(NULL, pos, FW_CFG_DMA_CTL_SKIP);
 185                 if (ret < 0)
 186                         goto end;
 187                 ret = fw_cfg_dma_transfer(buf, count, FW_CFG_DMA_CTL_WRITE);
 188         }
 189
 190 end:
 191         mutex_unlock(&fw_cfg_dev_lock);
 192
 193         acpi_release_global_lock(glk);
 194
 195         return ret;
 196 }
 197 #endif /* CONFIG_CRASH_CORE */
 198
 199 /* clean up fw_cfg device i/o */
 200 static void fw_cfg_io_cleanup(void)
 201 {
 202         if (fw_cfg_is_mmio) {
 203                 iounmap(fw_cfg_dev_base);
 204                 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
 205         } else {
 206                 ioport_unmap(fw_cfg_dev_base);
 207                 release_region(fw_cfg_p_base, fw_cfg_p_size);
 208         }
 209 }
 210
 211 /* arch-specific ctrl & data register offsets are not available in ACPI, DT */
 212 #if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CFG_DATA_OFF))
 213 # if (defined(CONFIG_ARM) || defined(CONFIG_ARM64))
 214 #  define FW_CFG_CTRL_OFF 0x08
 215 #  define FW_CFG_DATA_OFF 0x00
 216 #  define FW_CFG_DMA_OFF 0x10
 217 # elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
 218 #  define FW_CFG_CTRL_OFF 0x00
 219 #  define FW_CFG_DATA_OFF 0x02
 220 # elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
 221 #  define FW_CFG_CTRL_OFF 0x00
 222 #  define FW_CFG_DATA_OFF 0x01
 223 #  define FW_CFG_DMA_OFF 0x04
 224 # else
 225 #  error "QEMU FW_CFG not available on this architecture!"
 226 # endif
 227 #endif
 228
 229 /* initialize fw_cfg device i/o from platform data */
 230 static int fw_cfg_do_platform_probe(struct platform_device *pdev)
 231 {
 232         char sig[FW_CFG_SIG_SIZE];
 233         struct resource *range, *ctrl, *data, *dma;
 234
 235         /* acquire i/o range details */
 236         fw_cfg_is_mmio = false;
 237         range = platform_get_resource(pdev, IORESOURCE_IO, 0);
 238         if (!range) {
 239                 fw_cfg_is_mmio = true;
 240                 range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 241                 if (!range)
 242                         return -EINVAL;
 243         }
 244         fw_cfg_p_base = range->start;
 245         fw_cfg_p_size = resource_size(range);
 246
 247         if (fw_cfg_is_mmio) {
 248                 if (!request_mem_region(fw_cfg_p_base,
 249                                         fw_cfg_p_size, "fw_cfg_mem"))
 250                         return -EBUSY;
 251                 fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);
 252                 if (!fw_cfg_dev_base) {
 253                         release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
 254                         return -EFAULT;
 255                 }
 256         } else {
 257                 if (!request_region(fw_cfg_p_base,
 258                                     fw_cfg_p_size, "fw_cfg_io"))
 259                         return -EBUSY;
 260                 fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);
 261                 if (!fw_cfg_dev_base) {
 262                         release_region(fw_cfg_p_base, fw_cfg_p_size);
 263                         return -EFAULT;
 264                 }
 265         }
 266
 267         /* were custom register offsets provided (e.g. on the command line)? */
 268         ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
 269         data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
 270         dma = platform_get_resource_byname(pdev, IORESOURCE_REG, "dma");
 271         if (ctrl && data) {
 272                 fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
 273                 fw_cfg_reg_data = fw_cfg_dev_base + data->start;
 274         } else {
 275                 /* use architecture-specific offsets */
 276                 fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;
 277                 fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;
 278         }
 279
 280         if (dma)
 281                 fw_cfg_reg_dma = fw_cfg_dev_base + dma->start;
 282 #ifdef FW_CFG_DMA_OFF
 283         else
 284                 fw_cfg_reg_dma = fw_cfg_dev_base + FW_CFG_DMA_OFF;
 285 #endif
 286
 287         /* verify fw_cfg device signature */
 288         if (fw_cfg_read_blob(FW_CFG_SIGNATURE, sig,
 289                                 0, FW_CFG_SIG_SIZE) < 0 ||
 290                 memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
 291                 fw_cfg_io_cleanup();
 292                 return -ENODEV;
 293         }
 294
 295         return 0;
 296 }
 297
 298 static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
 299 {
 300         return sprintf(buf, "%u\n", fw_cfg_rev);
 301 }
 302
 303 static const struct {
 304         struct attribute attr;
 305         ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
 306 } fw_cfg_rev_attr = {
 307         .attr = { .name = "rev", .mode = S_IRUSR },
 308         .show = fw_cfg_showrev,
 309 };
 310
 311 /* fw_cfg_sysfs_entry type */
 312 struct fw_cfg_sysfs_entry {
 313         struct kobject kobj;
 314         u32 size;
 315         u16 select;
 316         char name[FW_CFG_MAX_FILE_PATH];
 317         struct list_head list;
 318 };
 319
 320 #ifdef CONFIG_CRASH_CORE
 321 static ssize_t fw_cfg_write_vmcoreinfo(const struct fw_cfg_file *f)
 322 {
 323         static struct fw_cfg_vmcoreinfo *data;
 324         ssize_t ret;
 325
 326         data = kmalloc(sizeof(struct fw_cfg_vmcoreinfo), GFP_KERNEL);
 327         if (!data)
 328                 return -ENOMEM;
 329
 330         *data = (struct fw_cfg_vmcoreinfo) {
 331                 .guest_format = cpu_to_le16(FW_CFG_VMCOREINFO_FORMAT_ELF),
 332                 .size = cpu_to_le32(VMCOREINFO_NOTE_SIZE),
 333                 .paddr = cpu_to_le64(paddr_vmcoreinfo_note())
 334         };
 335         /* spare ourself reading host format support for now since we
 336          * don't know what else to format - host may ignore ours
 337          */
 338         ret = fw_cfg_write_blob(be16_to_cpu(f->select), data,
 339                                 0, sizeof(struct fw_cfg_vmcoreinfo));
 340
 341         kfree(data);
 342         return ret;
 343 }
 344 #endif /* CONFIG_CRASH_CORE */
 345
 346 /* get fw_cfg_sysfs_entry from kobject member */
 347 static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
 348 {
 349         return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
 350 }
 351
 352 /* fw_cfg_sysfs_attribute type */
 353 struct fw_cfg_sysfs_attribute {
 354         struct attribute attr;
 355         ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
 356 };
 357
 358 /* get fw_cfg_sysfs_attribute from attribute member */
 359 static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
 360 {
 361         return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
 362 }
 363
 364 /* global cache of fw_cfg_sysfs_entry objects */
 365 static LIST_HEAD(fw_cfg_entry_cache);
 366
 367 /* kobjects removed lazily by kernel, mutual exclusion needed */
 368 static DEFINE_SPINLOCK(fw_cfg_cache_lock);
 369
 370 static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
 371 {
 372         spin_lock(&fw_cfg_cache_lock);
 373         list_add_tail(&entry->list, &fw_cfg_entry_cache);
 374         spin_unlock(&fw_cfg_cache_lock);
 375 }
 376
 377 static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
 378 {
 379         spin_lock(&fw_cfg_cache_lock);
 380         list_del(&entry->list);
 381         spin_unlock(&fw_cfg_cache_lock);
 382 }
 383
 384 static void fw_cfg_sysfs_cache_cleanup(void)
 385 {
 386         struct fw_cfg_sysfs_entry *entry, *next;
 387
 388         list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
 389                 /* will end up invoking fw_cfg_sysfs_cache_delist()
 390                  * via each object's release() method (i.e. destructor)
 391                  */
 392                 kobject_put(&entry->kobj);
 393         }
 394 }
 395
 396 /* default_attrs: per-entry attributes and show methods */
 397
 398 #define FW_CFG_SYSFS_ATTR(_attr) \
 399 struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \
 400         .attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \
 401         .show = fw_cfg_sysfs_show_##_attr, \
 402 }
 403
 404 static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
 405 {
 406         return sprintf(buf, "%u\n", e->size);
 407 }
 408
 409 static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
 410 {
 411         return sprintf(buf, "%u\n", e->select);
 412 }
 413
 414 static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
 415 {
 416         return sprintf(buf, "%s\n", e->name);
 417 }
 418
 419 static FW_CFG_SYSFS_ATTR(size);
 420 static FW_CFG_SYSFS_ATTR(key);
 421 static FW_CFG_SYSFS_ATTR(name);
 422
 423 static struct attribute *fw_cfg_sysfs_entry_attrs[] = {
 424         &fw_cfg_sysfs_attr_size.attr,
 425         &fw_cfg_sysfs_attr_key.attr,
 426         &fw_cfg_sysfs_attr_name.attr,
 427         NULL,
 428 };
 429
 430 /* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
 431 static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
 432                                       char *buf)
 433 {
 434         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 435         struct fw_cfg_sysfs_attribute *attr = to_attr(a);
 436
 437         return attr->show(entry, buf);
 438 }
 439
 440 static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
 441         .show = fw_cfg_sysfs_attr_show,
 442 };
 443
 444 /* release: destructor, to be called via kobject_put() */
 445 static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
 446 {
 447         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 448
 449         fw_cfg_sysfs_cache_delist(entry);
 450         kfree(entry);
 451 }
 452
 453 /* kobj_type: ties together all properties required to register an entry */
 454 static struct kobj_type fw_cfg_sysfs_entry_ktype = {
 455         .default_attrs = fw_cfg_sysfs_entry_attrs,
 456         .sysfs_ops = &fw_cfg_sysfs_attr_ops,
 457         .release = fw_cfg_sysfs_release_entry,
 458 };
 459
 460 /* raw-read method and attribute */
 461 static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
 462                                      struct bin_attribute *bin_attr,
 463                                      char *buf, loff_t pos, size_t count)
 464 {
 465         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 466
 467         if (pos > entry->size)
 468                 return -EINVAL;
 469
 470         if (count > entry->size - pos)
 471                 count = entry->size - pos;
 472
 473         return fw_cfg_read_blob(entry->select, buf, pos, count);
 474 }
 475
 476 static struct bin_attribute fw_cfg_sysfs_attr_raw = {
 477         .attr = { .name = "raw", .mode = S_IRUSR },
 478         .read = fw_cfg_sysfs_read_raw,
 479 };
 480
 481 /*
 482  * Create a kset subdirectory matching each '/' delimited dirname token
 483  * in 'name', starting with sysfs kset/folder 'dir'; At the end, create
 484  * a symlink directed at the given 'target'.
 485  * NOTE: We do this on a best-effort basis, since 'name' is not guaranteed
 486  * to be a well-behaved path name. Whenever a symlink vs. kset directory
 487  * name collision occurs, the kernel will issue big scary warnings while
 488  * refusing to add the offending link or directory. We follow up with our
 489  * own, slightly less scary error messages explaining the situation :)
 490  */
 491 static int fw_cfg_build_symlink(struct kset *dir,
 492                                 struct kobject *target, const char *name)
 493 {
 494         int ret;
 495         struct kset *subdir;
 496         struct kobject *ko;
 497         char *name_copy, *p, *tok;
 498
 499         if (!dir || !target || !name || !*name)
 500                 return -EINVAL;
 501
 502         /* clone a copy of name for parsing */
 503         name_copy = p = kstrdup(name, GFP_KERNEL);
 504         if (!name_copy)
 505                 return -ENOMEM;
 506
 507         /* create folders for each dirname token, then symlink for basename */
 508         while ((tok = strsep(&p, "/")) && *tok) {
 509
 510                 /* last (basename) token? If so, add symlink here */
 511                 if (!p || !*p) {
 512                         ret = sysfs_create_link(&dir->kobj, target, tok);
 513                         break;
 514                 }
 515
 516                 /* does the current dir contain an item named after tok ? */
 517                 ko = kset_find_obj(dir, tok);
 518                 if (ko) {
 519                         /* drop reference added by kset_find_obj */
 520                         kobject_put(ko);
 521
 522                         /* ko MUST be a kset - we're about to use it as one ! */
 523                         if (ko->ktype != dir->kobj.ktype) {
 524                                 ret = -EINVAL;
 525                                 break;
 526                         }
 527
 528                         /* descend into already existing subdirectory */
 529                         dir = to_kset(ko);
 530                 } else {
 531                         /* create new subdirectory kset */
 532                         subdir = kzalloc(sizeof(struct kset), GFP_KERNEL);
 533                         if (!subdir) {
 534                                 ret = -ENOMEM;
 535                                 break;
 536                         }
 537                         subdir->kobj.kset = dir;
 538                         subdir->kobj.ktype = dir->kobj.ktype;
 539                         ret = kobject_set_name(&subdir->kobj, "%s", tok);
 540                         if (ret) {
 541                                 kfree(subdir);
 542                                 break;
 543                         }
 544                         ret = kset_register(subdir);
 545                         if (ret) {
 546                                 kfree(subdir);
 547                                 break;
 548                         }
 549
 550                         /* descend into newly created subdirectory */
 551                         dir = subdir;
 552                 }
 553         }
 554
 555         /* we're done with cloned copy of name */
 556         kfree(name_copy);
 557         return ret;
 558 }
 559
 560 /* recursively unregister fw_cfg/by_name/ kset directory tree */
 561 static void fw_cfg_kset_unregister_recursive(struct kset *kset)
 562 {
 563         struct kobject *k, *next;
 564
 565         list_for_each_entry_safe(k, next, &kset->list, entry)
 566                 /* all set members are ksets too, but check just in case... */
 567                 if (k->ktype == kset->kobj.ktype)
 568                         fw_cfg_kset_unregister_recursive(to_kset(k));
 569
 570         /* symlinks are cleanly and automatically removed with the directory */
 571         kset_unregister(kset);
 572 }
 573
 574 /* kobjects & kset representing top-level, by_key, and by_name folders */
 575 static struct kobject *fw_cfg_top_ko;
 576 static struct kobject *fw_cfg_sel_ko;
 577 static struct kset *fw_cfg_fname_kset;
 578
 579 /* register an individual fw_cfg file */
 580 static int fw_cfg_register_file(const struct fw_cfg_file *f)
 581 {
 582         int err;
 583         struct fw_cfg_sysfs_entry *entry;
 584
 585 #ifdef CONFIG_CRASH_CORE
 586         if (fw_cfg_dma_enabled() &&
 587                 strcmp(f->name, FW_CFG_VMCOREINFO_FILENAME) == 0 &&
 588                 !is_kdump_kernel()) {
 589                 if (fw_cfg_write_vmcoreinfo(f) < 0)
 590                         pr_warn("fw_cfg: failed to write vmcoreinfo");
 591         }
 592 #endif
 593
 594         /* allocate new entry */
 595         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 596         if (!entry)
 597                 return -ENOMEM;
 598
 599         /* set file entry information */
 600         entry->size = be32_to_cpu(f->size);
 601         entry->select = be16_to_cpu(f->select);
 602         memcpy(entry->name, f->name, FW_CFG_MAX_FILE_PATH);
 603
 604         /* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
 605         err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
 606                                    fw_cfg_sel_ko, "%d", entry->select);
 607         if (err)
 608                 goto err_register;
 609
 610         /* add raw binary content access */
 611         err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
 612         if (err)
 613                 goto err_add_raw;
 614
 615         /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
 616         fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->name);
 617
 618         /* success, add entry to global cache */
 619         fw_cfg_sysfs_cache_enlist(entry);
 620         return 0;
 621
 622 err_add_raw:
 623         kobject_del(&entry->kobj);
 624 err_register:
 625         kfree(entry);
 626         return err;
 627 }
 628
 629 /* iterate over all fw_cfg directory entries, registering each one */
 630 static int fw_cfg_register_dir_entries(void)
 631 {
 632         int ret = 0;
 633         __be32 files_count;
 634         u32 count, i;
 635         struct fw_cfg_file *dir;
 636         size_t dir_size;
 637
 638         ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, &files_count,
 639                         0, sizeof(files_count));
 640         if (ret < 0)
 641                 return ret;
 642
 643         count = be32_to_cpu(files_count);
 644         dir_size = count * sizeof(struct fw_cfg_file);
 645
 646         dir = kmalloc(dir_size, GFP_KERNEL);
 647         if (!dir)
 648                 return -ENOMEM;
 649
 650         ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, dir,
 651                         sizeof(files_count), dir_size);
 652         if (ret < 0)
 653                 goto end;
 654
 655         for (i = 0; i < count; i++) {
 656                 ret = fw_cfg_register_file(&dir[i]);
 657                 if (ret)
 658                         break;
 659         }
 660
 661 end:
 662         kfree(dir);
 663         return ret;
 664 }
 665
 666 /* unregister top-level or by_key folder */
 667 static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
 668 {
 669         kobject_del(kobj);
 670         kobject_put(kobj);
 671 }
 672
 673 static int fw_cfg_sysfs_probe(struct platform_device *pdev)
 674 {
 675         int err;
 676         __le32 rev;
 677
 678         /* NOTE: If we supported multiple fw_cfg devices, we'd first create
 679          * a subdirectory named after e.g. pdev->id, then hang per-device
 680          * by_key (and by_name) subdirectories underneath it. However, only
 681          * one fw_cfg device exist system-wide, so if one was already found
 682          * earlier, we might as well stop here.
 683          */
 684         if (fw_cfg_sel_ko)
 685                 return -EBUSY;
 686
 687         /* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
 688         err = -ENOMEM;
 689         fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
 690         if (!fw_cfg_sel_ko)
 691                 goto err_sel;
 692         fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
 693         if (!fw_cfg_fname_kset)
 694                 goto err_name;
 695
 696         /* initialize fw_cfg device i/o from platform data */
 697         err = fw_cfg_do_platform_probe(pdev);
 698         if (err)
 699                 goto err_probe;
 700
 701         /* get revision number, add matching top-level attribute */
 702         err = fw_cfg_read_blob(FW_CFG_ID, &rev, 0, sizeof(rev));
 703         if (err < 0)
 704                 goto err_probe;
 705
 706         fw_cfg_rev = le32_to_cpu(rev);
 707         err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 708         if (err)
 709                 goto err_rev;
 710
 711         /* process fw_cfg file directory entry, registering each file */
 712         err = fw_cfg_register_dir_entries();
 713         if (err)
 714                 goto err_dir;
 715
 716         /* success */
 717         pr_debug("fw_cfg: loaded.\n");
 718         return 0;
 719
 720 err_dir:
 721         fw_cfg_sysfs_cache_cleanup();
 722         sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 723 err_rev:
 724         fw_cfg_io_cleanup();
 725 err_probe:
 726         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 727 err_name:
 728         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 729 err_sel:
 730         return err;
 731 }
 732
 733 static int fw_cfg_sysfs_remove(struct platform_device *pdev)
 734 {
 735         pr_debug("fw_cfg: unloading.\n");
 736         fw_cfg_sysfs_cache_cleanup();
 737         sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 738         fw_cfg_io_cleanup();
 739         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 740         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 741         return 0;
 742 }
 743
 744 static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
 745         { .compatible = "qemu,fw-cfg-mmio", },
 746         {},
 747 };
 748 MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);
 749
 750 #ifdef CONFIG_ACPI
 751 static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {
 752         { FW_CFG_ACPI_DEVICE_ID, },
 753         {},
 754 };
 755 MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
 756 #endif
 757
 758 static struct platform_driver fw_cfg_sysfs_driver = {
 759         .probe = fw_cfg_sysfs_probe,
 760         .remove = fw_cfg_sysfs_remove,
 761         .driver = {
 762                 .name = "fw_cfg",
 763                 .of_match_table = fw_cfg_sysfs_mmio_match,
 764                 .acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),
 765         },
 766 };
 767
 768 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
 769
 770 static struct platform_device *fw_cfg_cmdline_dev;
 771
 772 /* this probably belongs in e.g. include/linux/types.h,
 773  * but right now we are the only ones doing it...
 774  */
 775 #ifdef CONFIG_PHYS_ADDR_T_64BIT
 776 #define __PHYS_ADDR_PREFIX "ll"
 777 #else
 778 #define __PHYS_ADDR_PREFIX ""
 779 #endif
 780
 781 /* use special scanf/printf modifier for phys_addr_t, resource_size_t */
 782 #define PH_ADDR_SCAN_FMT "@%" __PHYS_ADDR_PREFIX "i%n" \
 783                          ":%" __PHYS_ADDR_PREFIX "i" \
 784                          ":%" __PHYS_ADDR_PREFIX "i%n" \
 785                          ":%" __PHYS_ADDR_PREFIX "i%n"
 786
 787 #define PH_ADDR_PR_1_FMT "0x%" __PHYS_ADDR_PREFIX "x@" \
 788                          "0x%" __PHYS_ADDR_PREFIX "x"
 789
 790 #define PH_ADDR_PR_3_FMT PH_ADDR_PR_1_FMT \
 791                          ":%" __PHYS_ADDR_PREFIX "u" \
 792                          ":%" __PHYS_ADDR_PREFIX "u"
 793
 794 #define PH_ADDR_PR_4_FMT PH_ADDR_PR_3_FMT \
 795                          ":%" __PHYS_ADDR_PREFIX "u"
 796
 797 static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)
 798 {
 799         struct resource res[4] = {};
 800         char *str;
 801         phys_addr_t base;
 802         resource_size_t size, ctrl_off, data_off, dma_off;
 803         int processed, consumed = 0;
 804
 805         /* only one fw_cfg device can exist system-wide, so if one
 806          * was processed on the command line already, we might as
 807          * well stop here.
 808          */
 809         if (fw_cfg_cmdline_dev) {
 810                 /* avoid leaking previously registered device */
 811                 platform_device_unregister(fw_cfg_cmdline_dev);
 812                 return -EINVAL;
 813         }
 814
 815         /* consume "<size>" portion of command line argument */
 816         size = memparse(arg, &str);
 817
 818         /* get "@<base>[:<ctrl_off>:<data_off>[:<dma_off>]]" chunks */
 819         processed = sscanf(str, PH_ADDR_SCAN_FMT,
 820                            &base, &consumed,
 821                            &ctrl_off, &data_off, &consumed,
 822                            &dma_off, &consumed);
 823
 824         /* sscanf() must process precisely 1, 3 or 4 chunks:
 825          * <base> is mandatory, optionally followed by <ctrl_off>
 826          * and <data_off>, and <dma_off>;
 827          * there must be no extra characters after the last chunk,
 828          * so str[consumed] must be '\0'.
 829          */
 830         if (str[consumed] ||
 831             (processed != 1 && processed != 3 && processed != 4))
 832                 return -EINVAL;
 833
 834         res[0].start = base;
 835         res[0].end = base + size - 1;
 836         res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :
 837                                                    IORESOURCE_IO;
 838
 839         /* insert register offsets, if provided */
 840         if (processed > 1) {
 841                 res[1].name = "ctrl";
 842                 res[1].start = ctrl_off;
 843                 res[1].flags = IORESOURCE_REG;
 844                 res[2].name = "data";
 845                 res[2].start = data_off;
 846                 res[2].flags = IORESOURCE_REG;
 847         }
 848         if (processed > 3) {
 849                 res[3].name = "dma";
 850                 res[3].start = dma_off;
 851                 res[3].flags = IORESOURCE_REG;
 852         }
 853
 854         /* "processed" happens to nicely match the number of resources
 855          * we need to pass in to this platform device.
 856          */
 857         fw_cfg_cmdline_dev = platform_device_register_simple("fw_cfg",
 858                                         PLATFORM_DEVID_NONE, res, processed);
 859
 860         return PTR_ERR_OR_ZERO(fw_cfg_cmdline_dev);
 861 }
 862
 863 static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)
 864 {
 865         /* stay silent if device was not configured via the command
 866          * line, or if the parameter name (ioport/mmio) doesn't match
 867          * the device setting
 868          */
 869         if (!fw_cfg_cmdline_dev ||
 870             (!strcmp(kp->name, "mmio") ^
 871              (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))
 872                 return 0;
 873
 874         switch (fw_cfg_cmdline_dev->num_resources) {
 875         case 1:
 876                 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_1_FMT,
 877                                 resource_size(&fw_cfg_cmdline_dev->resource[0]),
 878                                 fw_cfg_cmdline_dev->resource[0].start);
 879         case 3:
 880                 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_3_FMT,
 881                                 resource_size(&fw_cfg_cmdline_dev->resource[0]),
 882                                 fw_cfg_cmdline_dev->resource[0].start,
 883                                 fw_cfg_cmdline_dev->resource[1].start,
 884                                 fw_cfg_cmdline_dev->resource[2].start);
 885         case 4:
 886                 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_4_FMT,
 887                                 resource_size(&fw_cfg_cmdline_dev->resource[0]),
 888                                 fw_cfg_cmdline_dev->resource[0].start,
 889                                 fw_cfg_cmdline_dev->resource[1].start,
 890                                 fw_cfg_cmdline_dev->resource[2].start,
 891                                 fw_cfg_cmdline_dev->resource[3].start);
 892         }
 893
 894         /* Should never get here */
 895         WARN(1, "Unexpected number of resources: %d\n",
 896                 fw_cfg_cmdline_dev->num_resources);
 897         return 0;
 898 }
 899
 900 static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {
 901         .set = fw_cfg_cmdline_set,
 902         .get = fw_cfg_cmdline_get,
 903 };
 904
 905 device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 906 device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 907
 908 #endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */
 909
 910 static int __init fw_cfg_sysfs_init(void)
 911 {
 912         int ret;
 913
 914         /* create /sys/firmware/qemu_fw_cfg/ top level directory */
 915         fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
 916         if (!fw_cfg_top_ko)
 917                 return -ENOMEM;
 918
 919         ret = platform_driver_register(&fw_cfg_sysfs_driver);
 920         if (ret)
 921                 fw_cfg_kobj_cleanup(fw_cfg_top_ko);
 922
 923         return ret;
 924 }
 925
 926 static void __exit fw_cfg_sysfs_exit(void)
 927 {
 928         platform_driver_unregister(&fw_cfg_sysfs_driver);
 929
 930 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
 931         platform_device_unregister(fw_cfg_cmdline_dev);
 932 #endif
 933
 934         /* clean up /sys/firmware/qemu_fw_cfg/ */
 935         fw_cfg_kobj_cleanup(fw_cfg_top_ko);
 936 }
 937
 938 module_init(fw_cfg_sysfs_init);
 939 module_exit(fw_cfg_sysfs_exit);