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/mod_devicetable.h>
  32 #include <linux/platform_device.h>
  33 #include <linux/acpi.h>
  34 #include <linux/slab.h>
  35 #include <linux/io.h>
  36 #include <linux/ioport.h>
  37 #include <uapi/linux/qemu_fw_cfg.h>
  38 #include <linux/delay.h>
  39 #include <linux/crash_dump.h>
  40 #include <linux/vmcore_info.h>
  41
  42 MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
  43 MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
  44 MODULE_LICENSE("GPL");
  45
  46 /* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
  47 static u32 fw_cfg_rev;
  48
  49 /* fw_cfg device i/o register addresses */
  50 static bool fw_cfg_is_mmio;
  51 static phys_addr_t fw_cfg_p_base;
  52 static resource_size_t fw_cfg_p_size;
  53 static void __iomem *fw_cfg_dev_base;
  54 static void __iomem *fw_cfg_reg_ctrl;
  55 static void __iomem *fw_cfg_reg_data;
  56 static void __iomem *fw_cfg_reg_dma;
  57
  58 /* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */
  59 static DEFINE_MUTEX(fw_cfg_dev_lock);
  60
  61 /* pick appropriate endianness for selector key */
  62 static void fw_cfg_sel_endianness(u16 key)
  63 {
  64         if (fw_cfg_is_mmio)
  65                 iowrite16be(key, fw_cfg_reg_ctrl);
  66         else
  67                 iowrite16(key, fw_cfg_reg_ctrl);
  68 }
  69
  70 #ifdef CONFIG_VMCORE_INFO
  71 static inline bool fw_cfg_dma_enabled(void)
  72 {
  73         return (fw_cfg_rev & FW_CFG_VERSION_DMA) && fw_cfg_reg_dma;
  74 }
  75
  76 /* qemu fw_cfg device is sync today, but spec says it may become async */
  77 static void fw_cfg_wait_for_control(struct fw_cfg_dma_access *d)
  78 {
  79         for (;;) {
  80                 u32 ctrl = be32_to_cpu(READ_ONCE(d->control));
  81
  82                 /* do not reorder the read to d->control */
  83                 rmb();
  84                 if ((ctrl & ~FW_CFG_DMA_CTL_ERROR) == 0)
  85                         return;
  86
  87                 cpu_relax();
  88         }
  89 }
  90
  91 static ssize_t fw_cfg_dma_transfer(void *address, u32 length, u32 control)
  92 {
  93         phys_addr_t dma;
  94         struct fw_cfg_dma_access *d = NULL;
  95         ssize_t ret = length;
  96
  97         d = kmalloc(sizeof(*d), GFP_KERNEL);
  98         if (!d) {
  99                 ret = -ENOMEM;
 100                 goto end;
 101         }
 102
 103         /* fw_cfg device does not need IOMMU protection, so use physical addresses */
 104         *d = (struct fw_cfg_dma_access) {
 105                 .address = cpu_to_be64(address ? virt_to_phys(address) : 0),
 106                 .length = cpu_to_be32(length),
 107                 .control = cpu_to_be32(control)
 108         };
 109
 110         dma = virt_to_phys(d);
 111
 112         iowrite32be((u64)dma >> 32, fw_cfg_reg_dma);
 113         /* force memory to sync before notifying device via MMIO */
 114         wmb();
 115         iowrite32be(dma, fw_cfg_reg_dma + 4);
 116
 117         fw_cfg_wait_for_control(d);
 118
 119         if (be32_to_cpu(READ_ONCE(d->control)) & FW_CFG_DMA_CTL_ERROR) {
 120                 ret = -EIO;
 121         }
 122
 123 end:
 124         kfree(d);
 125
 126         return ret;
 127 }
 128 #endif
 129
 130 /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
 131 static ssize_t fw_cfg_read_blob(u16 key,
 132                                 void *buf, loff_t pos, size_t count)
 133 {
 134         u32 glk = -1U;
 135         acpi_status status;
 136
 137         /* If we have ACPI, ensure mutual exclusion against any potential
 138          * device access by the firmware, e.g. via AML methods:
 139          */
 140         status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
 141         if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
 142                 /* Should never get here */
 143                 WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
 144                 memset(buf, 0, count);
 145                 return -EINVAL;
 146         }
 147
 148         mutex_lock(&fw_cfg_dev_lock);
 149         fw_cfg_sel_endianness(key);
 150         while (pos-- > 0)
 151                 ioread8(fw_cfg_reg_data);
 152         ioread8_rep(fw_cfg_reg_data, buf, count);
 153         mutex_unlock(&fw_cfg_dev_lock);
 154
 155         acpi_release_global_lock(glk);
 156         return count;
 157 }
 158
 159 #ifdef CONFIG_VMCORE_INFO
 160 /* write chunk of given fw_cfg blob (caller responsible for sanity-check) */
 161 static ssize_t fw_cfg_write_blob(u16 key,
 162                                  void *buf, loff_t pos, size_t count)
 163 {
 164         u32 glk = -1U;
 165         acpi_status status;
 166         ssize_t ret = count;
 167
 168         /* If we have ACPI, ensure mutual exclusion against any potential
 169          * device access by the firmware, e.g. via AML methods:
 170          */
 171         status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
 172         if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
 173                 /* Should never get here */
 174                 WARN(1, "%s: Failed to lock ACPI!\n", __func__);
 175                 return -EINVAL;
 176         }
 177
 178         mutex_lock(&fw_cfg_dev_lock);
 179         if (pos == 0) {
 180                 ret = fw_cfg_dma_transfer(buf, count, key << 16
 181                                           | FW_CFG_DMA_CTL_SELECT
 182                                           | FW_CFG_DMA_CTL_WRITE);
 183         } else {
 184                 fw_cfg_sel_endianness(key);
 185                 ret = fw_cfg_dma_transfer(NULL, pos, FW_CFG_DMA_CTL_SKIP);
 186                 if (ret < 0)
 187                         goto end;
 188                 ret = fw_cfg_dma_transfer(buf, count, FW_CFG_DMA_CTL_WRITE);
 189         }
 190
 191 end:
 192         mutex_unlock(&fw_cfg_dev_lock);
 193
 194         acpi_release_global_lock(glk);
 195
 196         return ret;
 197 }
 198 #endif /* CONFIG_VMCORE_INFO */
 199
 200 /* clean up fw_cfg device i/o */
 201 static void fw_cfg_io_cleanup(void)
 202 {
 203         if (fw_cfg_is_mmio) {
 204                 iounmap(fw_cfg_dev_base);
 205                 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
 206         } else {
 207                 ioport_unmap(fw_cfg_dev_base);
 208                 release_region(fw_cfg_p_base, fw_cfg_p_size);
 209         }
 210 }
 211
 212 /* arch-specific ctrl & data register offsets are not available in ACPI, DT */
 213 #if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CFG_DATA_OFF))
 214 # if (defined(CONFIG_ARM) || defined(CONFIG_ARM64) || defined(CONFIG_RISCV))
 215 #  define FW_CFG_CTRL_OFF 0x08
 216 #  define FW_CFG_DATA_OFF 0x00
 217 #  define FW_CFG_DMA_OFF 0x10
 218 # elif defined(CONFIG_PARISC)   /* parisc */
 219 #  define FW_CFG_CTRL_OFF 0x00
 220 #  define FW_CFG_DATA_OFF 0x04
 221 # elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
 222 #  define FW_CFG_CTRL_OFF 0x00
 223 #  define FW_CFG_DATA_OFF 0x02
 224 # elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
 225 #  define FW_CFG_CTRL_OFF 0x00
 226 #  define FW_CFG_DATA_OFF 0x01
 227 #  define FW_CFG_DMA_OFF 0x04
 228 # else
 229 #  error "QEMU FW_CFG not available on this architecture!"
 230 # endif
 231 #endif
 232
 233 /* initialize fw_cfg device i/o from platform data */
 234 static int fw_cfg_do_platform_probe(struct platform_device *pdev)
 235 {
 236         char sig[FW_CFG_SIG_SIZE];
 237         struct resource *range, *ctrl, *data, *dma;
 238
 239         /* acquire i/o range details */
 240         fw_cfg_is_mmio = false;
 241         range = platform_get_resource(pdev, IORESOURCE_IO, 0);
 242         if (!range) {
 243                 fw_cfg_is_mmio = true;
 244                 range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 245                 if (!range)
 246                         return -EINVAL;
 247         }
 248         fw_cfg_p_base = range->start;
 249         fw_cfg_p_size = resource_size(range);
 250
 251         if (fw_cfg_is_mmio) {
 252                 if (!request_mem_region(fw_cfg_p_base,
 253                                         fw_cfg_p_size, "fw_cfg_mem"))
 254                         return -EBUSY;
 255                 fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);
 256                 if (!fw_cfg_dev_base) {
 257                         release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
 258                         return -EFAULT;
 259                 }
 260         } else {
 261                 if (!request_region(fw_cfg_p_base,
 262                                     fw_cfg_p_size, "fw_cfg_io"))
 263                         return -EBUSY;
 264                 fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);
 265                 if (!fw_cfg_dev_base) {
 266                         release_region(fw_cfg_p_base, fw_cfg_p_size);
 267                         return -EFAULT;
 268                 }
 269         }
 270
 271         /* were custom register offsets provided (e.g. on the command line)? */
 272         ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
 273         data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
 274         dma = platform_get_resource_byname(pdev, IORESOURCE_REG, "dma");
 275         if (ctrl && data) {
 276                 fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
 277                 fw_cfg_reg_data = fw_cfg_dev_base + data->start;
 278         } else {
 279                 /* use architecture-specific offsets */
 280                 fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;
 281                 fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;
 282         }
 283
 284         if (dma)
 285                 fw_cfg_reg_dma = fw_cfg_dev_base + dma->start;
 286 #ifdef FW_CFG_DMA_OFF
 287         else
 288                 fw_cfg_reg_dma = fw_cfg_dev_base + FW_CFG_DMA_OFF;
 289 #endif
 290
 291         /* verify fw_cfg device signature */
 292         if (fw_cfg_read_blob(FW_CFG_SIGNATURE, sig,
 293                                 0, FW_CFG_SIG_SIZE) < 0 ||
 294                 memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
 295                 fw_cfg_io_cleanup();
 296                 return -ENODEV;
 297         }
 298
 299         return 0;
 300 }
 301
 302 static ssize_t fw_cfg_showrev(struct kobject *k, struct kobj_attribute *a,
 303                               char *buf)
 304 {
 305         return sprintf(buf, "%u\n", fw_cfg_rev);
 306 }
 307
 308 static const struct kobj_attribute fw_cfg_rev_attr = {
 309         .attr = { .name = "rev", .mode = S_IRUSR },
 310         .show = fw_cfg_showrev,
 311 };
 312
 313 /* fw_cfg_sysfs_entry type */
 314 struct fw_cfg_sysfs_entry {
 315         struct kobject kobj;
 316         u32 size;
 317         u16 select;
 318         char name[FW_CFG_MAX_FILE_PATH];
 319         struct list_head list;
 320 };
 321
 322 #ifdef CONFIG_VMCORE_INFO
 323 static ssize_t fw_cfg_write_vmcoreinfo(const struct fw_cfg_file *f)
 324 {
 325         static struct fw_cfg_vmcoreinfo *data;
 326         ssize_t ret;
 327
 328         data = kmalloc(sizeof(struct fw_cfg_vmcoreinfo), GFP_KERNEL);
 329         if (!data)
 330                 return -ENOMEM;
 331
 332         *data = (struct fw_cfg_vmcoreinfo) {
 333                 .guest_format = cpu_to_le16(FW_CFG_VMCOREINFO_FORMAT_ELF),
 334                 .size = cpu_to_le32(VMCOREINFO_NOTE_SIZE),
 335                 .paddr = cpu_to_le64(paddr_vmcoreinfo_note())
 336         };
 337         /* spare ourself reading host format support for now since we
 338          * don't know what else to format - host may ignore ours
 339          */
 340         ret = fw_cfg_write_blob(be16_to_cpu(f->select), data,
 341                                 0, sizeof(struct fw_cfg_vmcoreinfo));
 342
 343         kfree(data);
 344         return ret;
 345 }
 346 #endif /* CONFIG_VMCORE_INFO */
 347
 348 /* get fw_cfg_sysfs_entry from kobject member */
 349 static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
 350 {
 351         return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
 352 }
 353
 354 /* fw_cfg_sysfs_attribute type */
 355 struct fw_cfg_sysfs_attribute {
 356         struct attribute attr;
 357         ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
 358 };
 359
 360 /* get fw_cfg_sysfs_attribute from attribute member */
 361 static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
 362 {
 363         return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
 364 }
 365
 366 /* global cache of fw_cfg_sysfs_entry objects */
 367 static LIST_HEAD(fw_cfg_entry_cache);
 368
 369 /* kobjects removed lazily by kernel, mutual exclusion needed */
 370 static DEFINE_SPINLOCK(fw_cfg_cache_lock);
 371
 372 static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
 373 {
 374         spin_lock(&fw_cfg_cache_lock);
 375         list_add_tail(&entry->list, &fw_cfg_entry_cache);
 376         spin_unlock(&fw_cfg_cache_lock);
 377 }
 378
 379 static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
 380 {
 381         spin_lock(&fw_cfg_cache_lock);
 382         list_del(&entry->list);
 383         spin_unlock(&fw_cfg_cache_lock);
 384 }
 385
 386 static void fw_cfg_sysfs_cache_cleanup(void)
 387 {
 388         struct fw_cfg_sysfs_entry *entry, *next;
 389
 390         list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
 391                 fw_cfg_sysfs_cache_delist(entry);
 392                 kobject_del(&entry->kobj);
 393                 kobject_put(&entry->kobj);
 394         }
 395 }
 396
 397 /* per-entry attributes and show methods */
 398
 399 #define FW_CFG_SYSFS_ATTR(_attr) \
 400 struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \
 401         .attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \
 402         .show = fw_cfg_sysfs_show_##_attr, \
 403 }
 404
 405 static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
 406 {
 407         return sprintf(buf, "%u\n", e->size);
 408 }
 409
 410 static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
 411 {
 412         return sprintf(buf, "%u\n", e->select);
 413 }
 414
 415 static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
 416 {
 417         return sprintf(buf, "%s\n", e->name);
 418 }
 419
 420 static FW_CFG_SYSFS_ATTR(size);
 421 static FW_CFG_SYSFS_ATTR(key);
 422 static FW_CFG_SYSFS_ATTR(name);
 423
 424 static struct attribute *fw_cfg_sysfs_entry_attrs[] = {
 425         &fw_cfg_sysfs_attr_size.attr,
 426         &fw_cfg_sysfs_attr_key.attr,
 427         &fw_cfg_sysfs_attr_name.attr,
 428         NULL,
 429 };
 430 ATTRIBUTE_GROUPS(fw_cfg_sysfs_entry);
 431
 432 /* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
 433 static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
 434                                       char *buf)
 435 {
 436         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 437         struct fw_cfg_sysfs_attribute *attr = to_attr(a);
 438
 439         return attr->show(entry, buf);
 440 }
 441
 442 static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
 443         .show = fw_cfg_sysfs_attr_show,
 444 };
 445
 446 /* release: destructor, to be called via kobject_put() */
 447 static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
 448 {
 449         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 450
 451         kfree(entry);
 452 }
 453
 454 /* kobj_type: ties together all properties required to register an entry */
 455 static const struct kobj_type fw_cfg_sysfs_entry_ktype = {
 456         .default_groups = fw_cfg_sysfs_entry_groups,
 457         .sysfs_ops = &fw_cfg_sysfs_attr_ops,
 458         .release = fw_cfg_sysfs_release_entry,
 459 };
 460
 461 /* raw-read method and attribute */
 462 static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
 463                                      struct bin_attribute *bin_attr,
 464                                      char *buf, loff_t pos, size_t count)
 465 {
 466         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 467
 468         if (pos > entry->size)
 469                 return -EINVAL;
 470
 471         if (count > entry->size - pos)
 472                 count = entry->size - pos;
 473
 474         return fw_cfg_read_blob(entry->select, buf, pos, count);
 475 }
 476
 477 static struct bin_attribute fw_cfg_sysfs_attr_raw = {
 478         .attr = { .name = "raw", .mode = S_IRUSR },
 479         .read = fw_cfg_sysfs_read_raw,
 480 };
 481
 482 /*
 483  * Create a kset subdirectory matching each '/' delimited dirname token
 484  * in 'name', starting with sysfs kset/folder 'dir'; At the end, create
 485  * a symlink directed at the given 'target'.
 486  * NOTE: We do this on a best-effort basis, since 'name' is not guaranteed
 487  * to be a well-behaved path name. Whenever a symlink vs. kset directory
 488  * name collision occurs, the kernel will issue big scary warnings while
 489  * refusing to add the offending link or directory. We follow up with our
 490  * own, slightly less scary error messages explaining the situation :)
 491  */
 492 static int fw_cfg_build_symlink(struct kset *dir,
 493                                 struct kobject *target, const char *name)
 494 {
 495         int ret;
 496         struct kset *subdir;
 497         struct kobject *ko;
 498         char *name_copy, *p, *tok;
 499
 500         if (!dir || !target || !name || !*name)
 501                 return -EINVAL;
 502
 503         /* clone a copy of name for parsing */
 504         name_copy = p = kstrdup(name, GFP_KERNEL);
 505         if (!name_copy)
 506                 return -ENOMEM;
 507
 508         /* create folders for each dirname token, then symlink for basename */
 509         while ((tok = strsep(&p, "/")) && *tok) {
 510
 511                 /* last (basename) token? If so, add symlink here */
 512                 if (!p || !*p) {
 513                         ret = sysfs_create_link(&dir->kobj, target, tok);
 514                         break;
 515                 }
 516
 517                 /* does the current dir contain an item named after tok ? */
 518                 ko = kset_find_obj(dir, tok);
 519                 if (ko) {
 520                         /* drop reference added by kset_find_obj */
 521                         kobject_put(ko);
 522
 523                         /* ko MUST be a kset - we're about to use it as one ! */
 524                         if (ko->ktype != dir->kobj.ktype) {
 525                                 ret = -EINVAL;
 526                                 break;
 527                         }
 528
 529                         /* descend into already existing subdirectory */
 530                         dir = to_kset(ko);
 531                 } else {
 532                         /* create new subdirectory kset */
 533                         subdir = kzalloc(sizeof(struct kset), GFP_KERNEL);
 534                         if (!subdir) {
 535                                 ret = -ENOMEM;
 536                                 break;
 537                         }
 538                         subdir->kobj.kset = dir;
 539                         subdir->kobj.ktype = dir->kobj.ktype;
 540                         ret = kobject_set_name(&subdir->kobj, "%s", tok);
 541                         if (ret) {
 542                                 kfree(subdir);
 543                                 break;
 544                         }
 545                         ret = kset_register(subdir);
 546                         if (ret) {
 547                                 kfree(subdir);
 548                                 break;
 549                         }
 550
 551                         /* descend into newly created subdirectory */
 552                         dir = subdir;
 553                 }
 554         }
 555
 556         /* we're done with cloned copy of name */
 557         kfree(name_copy);
 558         return ret;
 559 }
 560
 561 /* recursively unregister fw_cfg/by_name/ kset directory tree */
 562 static void fw_cfg_kset_unregister_recursive(struct kset *kset)
 563 {
 564         struct kobject *k, *next;
 565
 566         list_for_each_entry_safe(k, next, &kset->list, entry)
 567                 /* all set members are ksets too, but check just in case... */
 568                 if (k->ktype == kset->kobj.ktype)
 569                         fw_cfg_kset_unregister_recursive(to_kset(k));
 570
 571         /* symlinks are cleanly and automatically removed with the directory */
 572         kset_unregister(kset);
 573 }
 574
 575 /* kobjects & kset representing top-level, by_key, and by_name folders */
 576 static struct kobject *fw_cfg_top_ko;
 577 static struct kobject *fw_cfg_sel_ko;
 578 static struct kset *fw_cfg_fname_kset;
 579
 580 /* register an individual fw_cfg file */
 581 static int fw_cfg_register_file(const struct fw_cfg_file *f)
 582 {
 583         int err;
 584         struct fw_cfg_sysfs_entry *entry;
 585
 586 #ifdef CONFIG_VMCORE_INFO
 587         if (fw_cfg_dma_enabled() &&
 588                 strcmp(f->name, FW_CFG_VMCOREINFO_FILENAME) == 0 &&
 589                 !is_kdump_kernel()) {
 590                 if (fw_cfg_write_vmcoreinfo(f) < 0)
 591                         pr_warn("fw_cfg: failed to write vmcoreinfo");
 592         }
 593 #endif
 594
 595         /* allocate new entry */
 596         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 597         if (!entry)
 598                 return -ENOMEM;
 599
 600         /* set file entry information */
 601         entry->size = be32_to_cpu(f->size);
 602         entry->select = be16_to_cpu(f->select);
 603         strscpy(entry->name, f->name, FW_CFG_MAX_FILE_PATH);
 604
 605         /* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
 606         err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
 607                                    fw_cfg_sel_ko, "%d", entry->select);
 608         if (err)
 609                 goto err_put_entry;
 610
 611         /* add raw binary content access */
 612         err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
 613         if (err)
 614                 goto err_del_entry;
 615
 616         /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
 617         fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->name);
 618
 619         /* success, add entry to global cache */
 620         fw_cfg_sysfs_cache_enlist(entry);
 621         return 0;
 622
 623 err_del_entry:
 624         kobject_del(&entry->kobj);
 625 err_put_entry:
 626         kobject_put(&entry->kobj);
 627         return err;
 628 }
 629
 630 /* iterate over all fw_cfg directory entries, registering each one */
 631 static int fw_cfg_register_dir_entries(void)
 632 {
 633         int ret = 0;
 634         __be32 files_count;
 635         u32 count, i;
 636         struct fw_cfg_file *dir;
 637         size_t dir_size;
 638
 639         ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, &files_count,
 640                         0, sizeof(files_count));
 641         if (ret < 0)
 642                 return ret;
 643
 644         count = be32_to_cpu(files_count);
 645         dir_size = count * sizeof(struct fw_cfg_file);
 646
 647         dir = kmalloc(dir_size, GFP_KERNEL);
 648         if (!dir)
 649                 return -ENOMEM;
 650
 651         ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, dir,
 652                         sizeof(files_count), dir_size);
 653         if (ret < 0)
 654                 goto end;
 655
 656         for (i = 0; i < count; i++) {
 657                 ret = fw_cfg_register_file(&dir[i]);
 658                 if (ret)
 659                         break;
 660         }
 661
 662 end:
 663         kfree(dir);
 664         return ret;
 665 }
 666
 667 /* unregister top-level or by_key folder */
 668 static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
 669 {
 670         kobject_del(kobj);
 671         kobject_put(kobj);
 672 }
 673
 674 static int fw_cfg_sysfs_probe(struct platform_device *pdev)
 675 {
 676         int err;
 677         __le32 rev;
 678
 679         /* NOTE: If we supported multiple fw_cfg devices, we'd first create
 680          * a subdirectory named after e.g. pdev->id, then hang per-device
 681          * by_key (and by_name) subdirectories underneath it. However, only
 682          * one fw_cfg device exist system-wide, so if one was already found
 683          * earlier, we might as well stop here.
 684          */
 685         if (fw_cfg_sel_ko)
 686                 return -EBUSY;
 687
 688         /* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
 689         err = -ENOMEM;
 690         fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
 691         if (!fw_cfg_sel_ko)
 692                 goto err_sel;
 693         fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
 694         if (!fw_cfg_fname_kset)
 695                 goto err_name;
 696
 697         /* initialize fw_cfg device i/o from platform data */
 698         err = fw_cfg_do_platform_probe(pdev);
 699         if (err)
 700                 goto err_probe;
 701
 702         /* get revision number, add matching top-level attribute */
 703         err = fw_cfg_read_blob(FW_CFG_ID, &rev, 0, sizeof(rev));
 704         if (err < 0)
 705                 goto err_probe;
 706
 707         fw_cfg_rev = le32_to_cpu(rev);
 708         err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 709         if (err)
 710                 goto err_rev;
 711
 712         /* process fw_cfg file directory entry, registering each file */
 713         err = fw_cfg_register_dir_entries();
 714         if (err)
 715                 goto err_dir;
 716
 717         /* success */
 718         pr_debug("fw_cfg: loaded.\n");
 719         return 0;
 720
 721 err_dir:
 722         fw_cfg_sysfs_cache_cleanup();
 723         sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 724 err_rev:
 725         fw_cfg_io_cleanup();
 726 err_probe:
 727         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 728 err_name:
 729         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 730 err_sel:
 731         return err;
 732 }
 733
 734 static void fw_cfg_sysfs_remove(struct platform_device *pdev)
 735 {
 736         pr_debug("fw_cfg: unloading.\n");
 737         fw_cfg_sysfs_cache_cleanup();
 738         sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 739         fw_cfg_io_cleanup();
 740         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 741         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 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_new = 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);