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  *      [fw_cfg.]ioport=<size>@<base>[:<ctrl_off>:<data_off>]
  14  * or
  15  *      [fw_cfg.]mmio=<size>@<base>[:<ctrl_off>:<data_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  *
  23  * e.g.:
  24  *      fw_cfg.ioport=2@0x510:0:1               (the default on x86)
  25  * or
  26  *      fw_cfg.mmio=0xA@0x9020000:8:0           (the default on arm)
  27  */
  28
  29 #include <linux/module.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/acpi.h>
  32 #include <linux/slab.h>
  33 #include <linux/io.h>
  34 #include <linux/ioport.h>
  35
  36 MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
  37 MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
  38 MODULE_LICENSE("GPL");
  39
  40 /* selector key values for "well-known" fw_cfg entries */
  41 #define FW_CFG_SIGNATURE  0x00
  42 #define FW_CFG_ID         0x01
  43 #define FW_CFG_FILE_DIR   0x19
  44
  45 /* size in bytes of fw_cfg signature */
  46 #define FW_CFG_SIG_SIZE 4
  47
  48 /* fw_cfg "file name" is up to 56 characters (including terminating nul) */
  49 #define FW_CFG_MAX_FILE_PATH 56
  50
  51 /* fw_cfg file directory entry type */
  52 struct fw_cfg_file {
  53         u32 size;
  54         u16 select;
  55         u16 reserved;
  56         char name[FW_CFG_MAX_FILE_PATH];
  57 };
  58
  59 /* fw_cfg device i/o register addresses */
  60 static bool fw_cfg_is_mmio;
  61 static phys_addr_t fw_cfg_p_base;
  62 static resource_size_t fw_cfg_p_size;
  63 static void __iomem *fw_cfg_dev_base;
  64 static void __iomem *fw_cfg_reg_ctrl;
  65 static void __iomem *fw_cfg_reg_data;
  66
  67 /* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */
  68 static DEFINE_MUTEX(fw_cfg_dev_lock);
  69
  70 /* pick appropriate endianness for selector key */
  71 static inline u16 fw_cfg_sel_endianness(u16 key)
  72 {
  73         return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key);
  74 }
  75
  76 /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
  77 static inline void fw_cfg_read_blob(u16 key,
  78                                     void *buf, loff_t pos, size_t count)
  79 {
  80         mutex_lock(&fw_cfg_dev_lock);
  81         iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
  82         while (pos-- > 0)
  83                 ioread8(fw_cfg_reg_data);
  84         ioread8_rep(fw_cfg_reg_data, buf, count);
  85         mutex_unlock(&fw_cfg_dev_lock);
  86 }
  87
  88 /* clean up fw_cfg device i/o */
  89 static void fw_cfg_io_cleanup(void)
  90 {
  91         if (fw_cfg_is_mmio) {
  92                 iounmap(fw_cfg_dev_base);
  93                 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
  94         } else {
  95                 ioport_unmap(fw_cfg_dev_base);
  96                 release_region(fw_cfg_p_base, fw_cfg_p_size);
  97         }
  98 }
  99
 100 /* arch-specific ctrl & data register offsets are not available in ACPI, DT */
 101 #if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CFG_DATA_OFF))
 102 # if (defined(CONFIG_ARM) || defined(CONFIG_ARM64))
 103 #  define FW_CFG_CTRL_OFF 0x08
 104 #  define FW_CFG_DATA_OFF 0x00
 105 # elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
 106 #  define FW_CFG_CTRL_OFF 0x00
 107 #  define FW_CFG_DATA_OFF 0x02
 108 # elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
 109 #  define FW_CFG_CTRL_OFF 0x00
 110 #  define FW_CFG_DATA_OFF 0x01
 111 # else
 112 #  warning "QEMU FW_CFG may not be available on this architecture!"
 113 #  define FW_CFG_CTRL_OFF 0x00
 114 #  define FW_CFG_DATA_OFF 0x01
 115 # endif
 116 #endif
 117
 118 /* initialize fw_cfg device i/o from platform data */
 119 static int fw_cfg_do_platform_probe(struct platform_device *pdev)
 120 {
 121         char sig[FW_CFG_SIG_SIZE];
 122         struct resource *range, *ctrl, *data;
 123
 124         /* acquire i/o range details */
 125         fw_cfg_is_mmio = false;
 126         range = platform_get_resource(pdev, IORESOURCE_IO, 0);
 127         if (!range) {
 128                 fw_cfg_is_mmio = true;
 129                 range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 130                 if (!range)
 131                         return -EINVAL;
 132         }
 133         fw_cfg_p_base = range->start;
 134         fw_cfg_p_size = resource_size(range);
 135
 136         if (fw_cfg_is_mmio) {
 137                 if (!request_mem_region(fw_cfg_p_base,
 138                                         fw_cfg_p_size, "fw_cfg_mem"))
 139                         return -EBUSY;
 140                 fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);
 141                 if (!fw_cfg_dev_base) {
 142                         release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
 143                         return -EFAULT;
 144                 }
 145         } else {
 146                 if (!request_region(fw_cfg_p_base,
 147                                     fw_cfg_p_size, "fw_cfg_io"))
 148                         return -EBUSY;
 149                 fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);
 150                 if (!fw_cfg_dev_base) {
 151                         release_region(fw_cfg_p_base, fw_cfg_p_size);
 152                         return -EFAULT;
 153                 }
 154         }
 155
 156         /* were custom register offsets provided (e.g. on the command line)? */
 157         ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
 158         data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
 159         if (ctrl && data) {
 160                 fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
 161                 fw_cfg_reg_data = fw_cfg_dev_base + data->start;
 162         } else {
 163                 /* use architecture-specific offsets */
 164                 fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;
 165                 fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;
 166         }
 167
 168         /* verify fw_cfg device signature */
 169         fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE);
 170         if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
 171                 fw_cfg_io_cleanup();
 172                 return -ENODEV;
 173         }
 174
 175         return 0;
 176 }
 177
 178 /* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
 179 static u32 fw_cfg_rev;
 180
 181 static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
 182 {
 183         return sprintf(buf, "%u\n", fw_cfg_rev);
 184 }
 185
 186 static const struct {
 187         struct attribute attr;
 188         ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
 189 } fw_cfg_rev_attr = {
 190         .attr = { .name = "rev", .mode = S_IRUSR },
 191         .show = fw_cfg_showrev,
 192 };
 193
 194 /* fw_cfg_sysfs_entry type */
 195 struct fw_cfg_sysfs_entry {
 196         struct kobject kobj;
 197         struct fw_cfg_file f;
 198         struct list_head list;
 199 };
 200
 201 /* get fw_cfg_sysfs_entry from kobject member */
 202 static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
 203 {
 204         return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
 205 }
 206
 207 /* fw_cfg_sysfs_attribute type */
 208 struct fw_cfg_sysfs_attribute {
 209         struct attribute attr;
 210         ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
 211 };
 212
 213 /* get fw_cfg_sysfs_attribute from attribute member */
 214 static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
 215 {
 216         return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
 217 }
 218
 219 /* global cache of fw_cfg_sysfs_entry objects */
 220 static LIST_HEAD(fw_cfg_entry_cache);
 221
 222 /* kobjects removed lazily by kernel, mutual exclusion needed */
 223 static DEFINE_SPINLOCK(fw_cfg_cache_lock);
 224
 225 static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
 226 {
 227         spin_lock(&fw_cfg_cache_lock);
 228         list_add_tail(&entry->list, &fw_cfg_entry_cache);
 229         spin_unlock(&fw_cfg_cache_lock);
 230 }
 231
 232 static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
 233 {
 234         spin_lock(&fw_cfg_cache_lock);
 235         list_del(&entry->list);
 236         spin_unlock(&fw_cfg_cache_lock);
 237 }
 238
 239 static void fw_cfg_sysfs_cache_cleanup(void)
 240 {
 241         struct fw_cfg_sysfs_entry *entry, *next;
 242
 243         list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
 244                 /* will end up invoking fw_cfg_sysfs_cache_delist()
 245                  * via each object's release() method (i.e. destructor)
 246                  */
 247                 kobject_put(&entry->kobj);
 248         }
 249 }
 250
 251 /* default_attrs: per-entry attributes and show methods */
 252
 253 #define FW_CFG_SYSFS_ATTR(_attr) \
 254 struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \
 255         .attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \
 256         .show = fw_cfg_sysfs_show_##_attr, \
 257 }
 258
 259 static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
 260 {
 261         return sprintf(buf, "%u\n", e->f.size);
 262 }
 263
 264 static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
 265 {
 266         return sprintf(buf, "%u\n", e->f.select);
 267 }
 268
 269 static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
 270 {
 271         return sprintf(buf, "%s\n", e->f.name);
 272 }
 273
 274 static FW_CFG_SYSFS_ATTR(size);
 275 static FW_CFG_SYSFS_ATTR(key);
 276 static FW_CFG_SYSFS_ATTR(name);
 277
 278 static struct attribute *fw_cfg_sysfs_entry_attrs[] = {
 279         &fw_cfg_sysfs_attr_size.attr,
 280         &fw_cfg_sysfs_attr_key.attr,
 281         &fw_cfg_sysfs_attr_name.attr,
 282         NULL,
 283 };
 284
 285 /* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
 286 static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
 287                                       char *buf)
 288 {
 289         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 290         struct fw_cfg_sysfs_attribute *attr = to_attr(a);
 291
 292         return attr->show(entry, buf);
 293 }
 294
 295 static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
 296         .show = fw_cfg_sysfs_attr_show,
 297 };
 298
 299 /* release: destructor, to be called via kobject_put() */
 300 static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
 301 {
 302         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 303
 304         fw_cfg_sysfs_cache_delist(entry);
 305         kfree(entry);
 306 }
 307
 308 /* kobj_type: ties together all properties required to register an entry */
 309 static struct kobj_type fw_cfg_sysfs_entry_ktype = {
 310         .default_attrs = fw_cfg_sysfs_entry_attrs,
 311         .sysfs_ops = &fw_cfg_sysfs_attr_ops,
 312         .release = fw_cfg_sysfs_release_entry,
 313 };
 314
 315 /* raw-read method and attribute */
 316 static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
 317                                      struct bin_attribute *bin_attr,
 318                                      char *buf, loff_t pos, size_t count)
 319 {
 320         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 321
 322         if (pos > entry->f.size)
 323                 return -EINVAL;
 324
 325         if (count > entry->f.size - pos)
 326                 count = entry->f.size - pos;
 327
 328         fw_cfg_read_blob(entry->f.select, buf, pos, count);
 329         return count;
 330 }
 331
 332 static struct bin_attribute fw_cfg_sysfs_attr_raw = {
 333         .attr = { .name = "raw", .mode = S_IRUSR },
 334         .read = fw_cfg_sysfs_read_raw,
 335 };
 336
 337 /*
 338  * Create a kset subdirectory matching each '/' delimited dirname token
 339  * in 'name', starting with sysfs kset/folder 'dir'; At the end, create
 340  * a symlink directed at the given 'target'.
 341  * NOTE: We do this on a best-effort basis, since 'name' is not guaranteed
 342  * to be a well-behaved path name. Whenever a symlink vs. kset directory
 343  * name collision occurs, the kernel will issue big scary warnings while
 344  * refusing to add the offending link or directory. We follow up with our
 345  * own, slightly less scary error messages explaining the situation :)
 346  */
 347 static int fw_cfg_build_symlink(struct kset *dir,
 348                                 struct kobject *target, const char *name)
 349 {
 350         int ret;
 351         struct kset *subdir;
 352         struct kobject *ko;
 353         char *name_copy, *p, *tok;
 354
 355         if (!dir || !target || !name || !*name)
 356                 return -EINVAL;
 357
 358         /* clone a copy of name for parsing */
 359         name_copy = p = kstrdup(name, GFP_KERNEL);
 360         if (!name_copy)
 361                 return -ENOMEM;
 362
 363         /* create folders for each dirname token, then symlink for basename */
 364         while ((tok = strsep(&p, "/")) && *tok) {
 365
 366                 /* last (basename) token? If so, add symlink here */
 367                 if (!p || !*p) {
 368                         ret = sysfs_create_link(&dir->kobj, target, tok);
 369                         break;
 370                 }
 371
 372                 /* does the current dir contain an item named after tok ? */
 373                 ko = kset_find_obj(dir, tok);
 374                 if (ko) {
 375                         /* drop reference added by kset_find_obj */
 376                         kobject_put(ko);
 377
 378                         /* ko MUST be a kset - we're about to use it as one ! */
 379                         if (ko->ktype != dir->kobj.ktype) {
 380                                 ret = -EINVAL;
 381                                 break;
 382                         }
 383
 384                         /* descend into already existing subdirectory */
 385                         dir = to_kset(ko);
 386                 } else {
 387                         /* create new subdirectory kset */
 388                         subdir = kzalloc(sizeof(struct kset), GFP_KERNEL);
 389                         if (!subdir) {
 390                                 ret = -ENOMEM;
 391                                 break;
 392                         }
 393                         subdir->kobj.kset = dir;
 394                         subdir->kobj.ktype = dir->kobj.ktype;
 395                         ret = kobject_set_name(&subdir->kobj, "%s", tok);
 396                         if (ret) {
 397                                 kfree(subdir);
 398                                 break;
 399                         }
 400                         ret = kset_register(subdir);
 401                         if (ret) {
 402                                 kfree(subdir);
 403                                 break;
 404                         }
 405
 406                         /* descend into newly created subdirectory */
 407                         dir = subdir;
 408                 }
 409         }
 410
 411         /* we're done with cloned copy of name */
 412         kfree(name_copy);
 413         return ret;
 414 }
 415
 416 /* recursively unregister fw_cfg/by_name/ kset directory tree */
 417 static void fw_cfg_kset_unregister_recursive(struct kset *kset)
 418 {
 419         struct kobject *k, *next;
 420
 421         list_for_each_entry_safe(k, next, &kset->list, entry)
 422                 /* all set members are ksets too, but check just in case... */
 423                 if (k->ktype == kset->kobj.ktype)
 424                         fw_cfg_kset_unregister_recursive(to_kset(k));
 425
 426         /* symlinks are cleanly and automatically removed with the directory */
 427         kset_unregister(kset);
 428 }
 429
 430 /* kobjects & kset representing top-level, by_key, and by_name folders */
 431 static struct kobject *fw_cfg_top_ko;
 432 static struct kobject *fw_cfg_sel_ko;
 433 static struct kset *fw_cfg_fname_kset;
 434
 435 /* register an individual fw_cfg file */
 436 static int fw_cfg_register_file(const struct fw_cfg_file *f)
 437 {
 438         int err;
 439         struct fw_cfg_sysfs_entry *entry;
 440
 441         /* allocate new entry */
 442         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 443         if (!entry)
 444                 return -ENOMEM;
 445
 446         /* set file entry information */
 447         memcpy(&entry->f, f, sizeof(struct fw_cfg_file));
 448
 449         /* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
 450         err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
 451                                    fw_cfg_sel_ko, "%d", entry->f.select);
 452         if (err)
 453                 goto err_register;
 454
 455         /* add raw binary content access */
 456         err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
 457         if (err)
 458                 goto err_add_raw;
 459
 460         /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
 461         fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->f.name);
 462
 463         /* success, add entry to global cache */
 464         fw_cfg_sysfs_cache_enlist(entry);
 465         return 0;
 466
 467 err_add_raw:
 468         kobject_del(&entry->kobj);
 469 err_register:
 470         kfree(entry);
 471         return err;
 472 }
 473
 474 /* iterate over all fw_cfg directory entries, registering each one */
 475 static int fw_cfg_register_dir_entries(void)
 476 {
 477         int ret = 0;
 478         u32 count, i;
 479         struct fw_cfg_file *dir;
 480         size_t dir_size;
 481
 482         fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count));
 483         count = be32_to_cpu(count);
 484         dir_size = count * sizeof(struct fw_cfg_file);
 485
 486         dir = kmalloc(dir_size, GFP_KERNEL);
 487         if (!dir)
 488                 return -ENOMEM;
 489
 490         fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size);
 491
 492         for (i = 0; i < count; i++) {
 493                 dir[i].size = be32_to_cpu(dir[i].size);
 494                 dir[i].select = be16_to_cpu(dir[i].select);
 495                 ret = fw_cfg_register_file(&dir[i]);
 496                 if (ret)
 497                         break;
 498         }
 499
 500         kfree(dir);
 501         return ret;
 502 }
 503
 504 /* unregister top-level or by_key folder */
 505 static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
 506 {
 507         kobject_del(kobj);
 508         kobject_put(kobj);
 509 }
 510
 511 static int fw_cfg_sysfs_probe(struct platform_device *pdev)
 512 {
 513         int err;
 514
 515         /* NOTE: If we supported multiple fw_cfg devices, we'd first create
 516          * a subdirectory named after e.g. pdev->id, then hang per-device
 517          * by_key (and by_name) subdirectories underneath it. However, only
 518          * one fw_cfg device exist system-wide, so if one was already found
 519          * earlier, we might as well stop here.
 520          */
 521         if (fw_cfg_sel_ko)
 522                 return -EBUSY;
 523
 524         /* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
 525         err = -ENOMEM;
 526         fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
 527         if (!fw_cfg_sel_ko)
 528                 goto err_sel;
 529         fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
 530         if (!fw_cfg_fname_kset)
 531                 goto err_name;
 532
 533         /* initialize fw_cfg device i/o from platform data */
 534         err = fw_cfg_do_platform_probe(pdev);
 535         if (err)
 536                 goto err_probe;
 537
 538         /* get revision number, add matching top-level attribute */
 539         fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev));
 540         fw_cfg_rev = le32_to_cpu(fw_cfg_rev);
 541         err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 542         if (err)
 543                 goto err_rev;
 544
 545         /* process fw_cfg file directory entry, registering each file */
 546         err = fw_cfg_register_dir_entries();
 547         if (err)
 548                 goto err_dir;
 549
 550         /* success */
 551         pr_debug("fw_cfg: loaded.\n");
 552         return 0;
 553
 554 err_dir:
 555         fw_cfg_sysfs_cache_cleanup();
 556         sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 557 err_rev:
 558         fw_cfg_io_cleanup();
 559 err_probe:
 560         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 561 err_name:
 562         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 563 err_sel:
 564         return err;
 565 }
 566
 567 static int fw_cfg_sysfs_remove(struct platform_device *pdev)
 568 {
 569         pr_debug("fw_cfg: unloading.\n");
 570         fw_cfg_sysfs_cache_cleanup();
 571         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 572         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 573         fw_cfg_io_cleanup();
 574         return 0;
 575 }
 576
 577 static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
 578         { .compatible = "qemu,fw-cfg-mmio", },
 579         {},
 580 };
 581 MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);
 582
 583 #ifdef CONFIG_ACPI
 584 static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {
 585         { "QEMU0002", },
 586         {},
 587 };
 588 MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
 589 #endif
 590
 591 static struct platform_driver fw_cfg_sysfs_driver = {
 592         .probe = fw_cfg_sysfs_probe,
 593         .remove = fw_cfg_sysfs_remove,
 594         .driver = {
 595                 .name = "fw_cfg",
 596                 .of_match_table = fw_cfg_sysfs_mmio_match,
 597                 .acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),
 598         },
 599 };
 600
 601 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
 602
 603 static struct platform_device *fw_cfg_cmdline_dev;
 604
 605 /* this probably belongs in e.g. include/linux/types.h,
 606  * but right now we are the only ones doing it...
 607  */
 608 #ifdef CONFIG_PHYS_ADDR_T_64BIT
 609 #define __PHYS_ADDR_PREFIX "ll"
 610 #else
 611 #define __PHYS_ADDR_PREFIX ""
 612 #endif
 613
 614 /* use special scanf/printf modifier for phys_addr_t, resource_size_t */
 615 #define PH_ADDR_SCAN_FMT "@%" __PHYS_ADDR_PREFIX "i%n" \
 616                          ":%" __PHYS_ADDR_PREFIX "i" \
 617                          ":%" __PHYS_ADDR_PREFIX "i%n"
 618
 619 #define PH_ADDR_PR_1_FMT "0x%" __PHYS_ADDR_PREFIX "x@" \
 620                          "0x%" __PHYS_ADDR_PREFIX "x"
 621
 622 #define PH_ADDR_PR_3_FMT PH_ADDR_PR_1_FMT \
 623                          ":%" __PHYS_ADDR_PREFIX "u" \
 624                          ":%" __PHYS_ADDR_PREFIX "u"
 625
 626 static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)
 627 {
 628         struct resource res[3] = {};
 629         char *str;
 630         phys_addr_t base;
 631         resource_size_t size, ctrl_off, data_off;
 632         int processed, consumed = 0;
 633
 634         /* only one fw_cfg device can exist system-wide, so if one
 635          * was processed on the command line already, we might as
 636          * well stop here.
 637          */
 638         if (fw_cfg_cmdline_dev) {
 639                 /* avoid leaking previously registered device */
 640                 platform_device_unregister(fw_cfg_cmdline_dev);
 641                 return -EINVAL;
 642         }
 643
 644         /* consume "<size>" portion of command line argument */
 645         size = memparse(arg, &str);
 646
 647         /* get "@<base>[:<ctrl_off>:<data_off>]" chunks */
 648         processed = sscanf(str, PH_ADDR_SCAN_FMT,
 649                            &base, &consumed,
 650                            &ctrl_off, &data_off, &consumed);
 651
 652         /* sscanf() must process precisely 1 or 3 chunks:
 653          * <base> is mandatory, optionally followed by <ctrl_off>
 654          * and <data_off>;
 655          * there must be no extra characters after the last chunk,
 656          * so str[consumed] must be '\0'.
 657          */
 658         if (str[consumed] ||
 659             (processed != 1 && processed != 3))
 660                 return -EINVAL;
 661
 662         res[0].start = base;
 663         res[0].end = base + size - 1;
 664         res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :
 665                                                    IORESOURCE_IO;
 666
 667         /* insert register offsets, if provided */
 668         if (processed > 1) {
 669                 res[1].name = "ctrl";
 670                 res[1].start = ctrl_off;
 671                 res[1].flags = IORESOURCE_REG;
 672                 res[2].name = "data";
 673                 res[2].start = data_off;
 674                 res[2].flags = IORESOURCE_REG;
 675         }
 676
 677         /* "processed" happens to nicely match the number of resources
 678          * we need to pass in to this platform device.
 679          */
 680         fw_cfg_cmdline_dev = platform_device_register_simple("fw_cfg",
 681                                         PLATFORM_DEVID_NONE, res, processed);
 682         if (IS_ERR(fw_cfg_cmdline_dev))
 683                 return PTR_ERR(fw_cfg_cmdline_dev);
 684
 685         return 0;
 686 }
 687
 688 static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)
 689 {
 690         /* stay silent if device was not configured via the command
 691          * line, or if the parameter name (ioport/mmio) doesn't match
 692          * the device setting
 693          */
 694         if (!fw_cfg_cmdline_dev ||
 695             (!strcmp(kp->name, "mmio") ^
 696              (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))
 697                 return 0;
 698
 699         switch (fw_cfg_cmdline_dev->num_resources) {
 700         case 1:
 701                 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_1_FMT,
 702                                 resource_size(&fw_cfg_cmdline_dev->resource[0]),
 703                                 fw_cfg_cmdline_dev->resource[0].start);
 704         case 3:
 705                 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_3_FMT,
 706                                 resource_size(&fw_cfg_cmdline_dev->resource[0]),
 707                                 fw_cfg_cmdline_dev->resource[0].start,
 708                                 fw_cfg_cmdline_dev->resource[1].start,
 709                                 fw_cfg_cmdline_dev->resource[2].start);
 710         }
 711
 712         /* Should never get here */
 713         WARN(1, "Unexpected number of resources: %d\n",
 714                 fw_cfg_cmdline_dev->num_resources);
 715         return 0;
 716 }
 717
 718 static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {
 719         .set = fw_cfg_cmdline_set,
 720         .get = fw_cfg_cmdline_get,
 721 };
 722
 723 device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 724 device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 725
 726 #endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */
 727
 728 static int __init fw_cfg_sysfs_init(void)
 729 {
 730         /* create /sys/firmware/qemu_fw_cfg/ top level directory */
 731         fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
 732         if (!fw_cfg_top_ko)
 733                 return -ENOMEM;
 734
 735         return platform_driver_register(&fw_cfg_sysfs_driver);
 736 }
 737
 738 static void __exit fw_cfg_sysfs_exit(void)
 739 {
 740         platform_driver_unregister(&fw_cfg_sysfs_driver);
 741
 742 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
 743         platform_device_unregister(fw_cfg_cmdline_dev);
 744 #endif
 745
 746         /* clean up /sys/firmware/qemu_fw_cfg/ */
 747         fw_cfg_kobj_cleanup(fw_cfg_top_ko);
 748 }
 749
 750 module_init(fw_cfg_sysfs_init);
 751 module_exit(fw_cfg_sysfs_exit);