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         u32 glk = -1U;
  81         acpi_status status;
  82
  83         /* If we have ACPI, ensure mutual exclusion against any potential
  84          * device access by the firmware, e.g. via AML methods:
  85          */
  86         status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
  87         if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
  88                 /* Should never get here */
  89                 WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
  90                 memset(buf, 0, count);
  91                 return;
  92         }
  93
  94         mutex_lock(&fw_cfg_dev_lock);
  95         iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
  96         while (pos-- > 0)
  97                 ioread8(fw_cfg_reg_data);
  98         ioread8_rep(fw_cfg_reg_data, buf, count);
  99         mutex_unlock(&fw_cfg_dev_lock);
 100
 101         acpi_release_global_lock(glk);
 102 }
 103
 104 /* clean up fw_cfg device i/o */
 105 static void fw_cfg_io_cleanup(void)
 106 {
 107         if (fw_cfg_is_mmio) {
 108                 iounmap(fw_cfg_dev_base);
 109                 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
 110         } else {
 111                 ioport_unmap(fw_cfg_dev_base);
 112                 release_region(fw_cfg_p_base, fw_cfg_p_size);
 113         }
 114 }
 115
 116 /* arch-specific ctrl & data register offsets are not available in ACPI, DT */
 117 #if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CFG_DATA_OFF))
 118 # if (defined(CONFIG_ARM) || defined(CONFIG_ARM64))
 119 #  define FW_CFG_CTRL_OFF 0x08
 120 #  define FW_CFG_DATA_OFF 0x00
 121 # elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
 122 #  define FW_CFG_CTRL_OFF 0x00
 123 #  define FW_CFG_DATA_OFF 0x02
 124 # elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
 125 #  define FW_CFG_CTRL_OFF 0x00
 126 #  define FW_CFG_DATA_OFF 0x01
 127 # else
 128 #  error "QEMU FW_CFG not available on this architecture!"
 129 # endif
 130 #endif
 131
 132 /* initialize fw_cfg device i/o from platform data */
 133 static int fw_cfg_do_platform_probe(struct platform_device *pdev)
 134 {
 135         char sig[FW_CFG_SIG_SIZE];
 136         struct resource *range, *ctrl, *data;
 137
 138         /* acquire i/o range details */
 139         fw_cfg_is_mmio = false;
 140         range = platform_get_resource(pdev, IORESOURCE_IO, 0);
 141         if (!range) {
 142                 fw_cfg_is_mmio = true;
 143                 range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 144                 if (!range)
 145                         return -EINVAL;
 146         }
 147         fw_cfg_p_base = range->start;
 148         fw_cfg_p_size = resource_size(range);
 149
 150         if (fw_cfg_is_mmio) {
 151                 if (!request_mem_region(fw_cfg_p_base,
 152                                         fw_cfg_p_size, "fw_cfg_mem"))
 153                         return -EBUSY;
 154                 fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);
 155                 if (!fw_cfg_dev_base) {
 156                         release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
 157                         return -EFAULT;
 158                 }
 159         } else {
 160                 if (!request_region(fw_cfg_p_base,
 161                                     fw_cfg_p_size, "fw_cfg_io"))
 162                         return -EBUSY;
 163                 fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);
 164                 if (!fw_cfg_dev_base) {
 165                         release_region(fw_cfg_p_base, fw_cfg_p_size);
 166                         return -EFAULT;
 167                 }
 168         }
 169
 170         /* were custom register offsets provided (e.g. on the command line)? */
 171         ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
 172         data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
 173         if (ctrl && data) {
 174                 fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
 175                 fw_cfg_reg_data = fw_cfg_dev_base + data->start;
 176         } else {
 177                 /* use architecture-specific offsets */
 178                 fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;
 179                 fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;
 180         }
 181
 182         /* verify fw_cfg device signature */
 183         fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE);
 184         if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
 185                 fw_cfg_io_cleanup();
 186                 return -ENODEV;
 187         }
 188
 189         return 0;
 190 }
 191
 192 /* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
 193 static u32 fw_cfg_rev;
 194
 195 static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
 196 {
 197         return sprintf(buf, "%u\n", fw_cfg_rev);
 198 }
 199
 200 static const struct {
 201         struct attribute attr;
 202         ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
 203 } fw_cfg_rev_attr = {
 204         .attr = { .name = "rev", .mode = S_IRUSR },
 205         .show = fw_cfg_showrev,
 206 };
 207
 208 /* fw_cfg_sysfs_entry type */
 209 struct fw_cfg_sysfs_entry {
 210         struct kobject kobj;
 211         struct fw_cfg_file f;
 212         struct list_head list;
 213 };
 214
 215 /* get fw_cfg_sysfs_entry from kobject member */
 216 static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
 217 {
 218         return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
 219 }
 220
 221 /* fw_cfg_sysfs_attribute type */
 222 struct fw_cfg_sysfs_attribute {
 223         struct attribute attr;
 224         ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
 225 };
 226
 227 /* get fw_cfg_sysfs_attribute from attribute member */
 228 static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
 229 {
 230         return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
 231 }
 232
 233 /* global cache of fw_cfg_sysfs_entry objects */
 234 static LIST_HEAD(fw_cfg_entry_cache);
 235
 236 /* kobjects removed lazily by kernel, mutual exclusion needed */
 237 static DEFINE_SPINLOCK(fw_cfg_cache_lock);
 238
 239 static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
 240 {
 241         spin_lock(&fw_cfg_cache_lock);
 242         list_add_tail(&entry->list, &fw_cfg_entry_cache);
 243         spin_unlock(&fw_cfg_cache_lock);
 244 }
 245
 246 static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
 247 {
 248         spin_lock(&fw_cfg_cache_lock);
 249         list_del(&entry->list);
 250         spin_unlock(&fw_cfg_cache_lock);
 251 }
 252
 253 static void fw_cfg_sysfs_cache_cleanup(void)
 254 {
 255         struct fw_cfg_sysfs_entry *entry, *next;
 256
 257         list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
 258                 /* will end up invoking fw_cfg_sysfs_cache_delist()
 259                  * via each object's release() method (i.e. destructor)
 260                  */
 261                 kobject_put(&entry->kobj);
 262         }
 263 }
 264
 265 /* default_attrs: per-entry attributes and show methods */
 266
 267 #define FW_CFG_SYSFS_ATTR(_attr) \
 268 struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \
 269         .attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \
 270         .show = fw_cfg_sysfs_show_##_attr, \
 271 }
 272
 273 static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
 274 {
 275         return sprintf(buf, "%u\n", e->f.size);
 276 }
 277
 278 static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
 279 {
 280         return sprintf(buf, "%u\n", e->f.select);
 281 }
 282
 283 static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
 284 {
 285         return sprintf(buf, "%s\n", e->f.name);
 286 }
 287
 288 static FW_CFG_SYSFS_ATTR(size);
 289 static FW_CFG_SYSFS_ATTR(key);
 290 static FW_CFG_SYSFS_ATTR(name);
 291
 292 static struct attribute *fw_cfg_sysfs_entry_attrs[] = {
 293         &fw_cfg_sysfs_attr_size.attr,
 294         &fw_cfg_sysfs_attr_key.attr,
 295         &fw_cfg_sysfs_attr_name.attr,
 296         NULL,
 297 };
 298
 299 /* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
 300 static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
 301                                       char *buf)
 302 {
 303         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 304         struct fw_cfg_sysfs_attribute *attr = to_attr(a);
 305
 306         return attr->show(entry, buf);
 307 }
 308
 309 static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
 310         .show = fw_cfg_sysfs_attr_show,
 311 };
 312
 313 /* release: destructor, to be called via kobject_put() */
 314 static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
 315 {
 316         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 317
 318         fw_cfg_sysfs_cache_delist(entry);
 319         kfree(entry);
 320 }
 321
 322 /* kobj_type: ties together all properties required to register an entry */
 323 static struct kobj_type fw_cfg_sysfs_entry_ktype = {
 324         .default_attrs = fw_cfg_sysfs_entry_attrs,
 325         .sysfs_ops = &fw_cfg_sysfs_attr_ops,
 326         .release = fw_cfg_sysfs_release_entry,
 327 };
 328
 329 /* raw-read method and attribute */
 330 static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
 331                                      struct bin_attribute *bin_attr,
 332                                      char *buf, loff_t pos, size_t count)
 333 {
 334         struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
 335
 336         if (pos > entry->f.size)
 337                 return -EINVAL;
 338
 339         if (count > entry->f.size - pos)
 340                 count = entry->f.size - pos;
 341
 342         fw_cfg_read_blob(entry->f.select, buf, pos, count);
 343         return count;
 344 }
 345
 346 static struct bin_attribute fw_cfg_sysfs_attr_raw = {
 347         .attr = { .name = "raw", .mode = S_IRUSR },
 348         .read = fw_cfg_sysfs_read_raw,
 349 };
 350
 351 /*
 352  * Create a kset subdirectory matching each '/' delimited dirname token
 353  * in 'name', starting with sysfs kset/folder 'dir'; At the end, create
 354  * a symlink directed at the given 'target'.
 355  * NOTE: We do this on a best-effort basis, since 'name' is not guaranteed
 356  * to be a well-behaved path name. Whenever a symlink vs. kset directory
 357  * name collision occurs, the kernel will issue big scary warnings while
 358  * refusing to add the offending link or directory. We follow up with our
 359  * own, slightly less scary error messages explaining the situation :)
 360  */
 361 static int fw_cfg_build_symlink(struct kset *dir,
 362                                 struct kobject *target, const char *name)
 363 {
 364         int ret;
 365         struct kset *subdir;
 366         struct kobject *ko;
 367         char *name_copy, *p, *tok;
 368
 369         if (!dir || !target || !name || !*name)
 370                 return -EINVAL;
 371
 372         /* clone a copy of name for parsing */
 373         name_copy = p = kstrdup(name, GFP_KERNEL);
 374         if (!name_copy)
 375                 return -ENOMEM;
 376
 377         /* create folders for each dirname token, then symlink for basename */
 378         while ((tok = strsep(&p, "/")) && *tok) {
 379
 380                 /* last (basename) token? If so, add symlink here */
 381                 if (!p || !*p) {
 382                         ret = sysfs_create_link(&dir->kobj, target, tok);
 383                         break;
 384                 }
 385
 386                 /* does the current dir contain an item named after tok ? */
 387                 ko = kset_find_obj(dir, tok);
 388                 if (ko) {
 389                         /* drop reference added by kset_find_obj */
 390                         kobject_put(ko);
 391
 392                         /* ko MUST be a kset - we're about to use it as one ! */
 393                         if (ko->ktype != dir->kobj.ktype) {
 394                                 ret = -EINVAL;
 395                                 break;
 396                         }
 397
 398                         /* descend into already existing subdirectory */
 399                         dir = to_kset(ko);
 400                 } else {
 401                         /* create new subdirectory kset */
 402                         subdir = kzalloc(sizeof(struct kset), GFP_KERNEL);
 403                         if (!subdir) {
 404                                 ret = -ENOMEM;
 405                                 break;
 406                         }
 407                         subdir->kobj.kset = dir;
 408                         subdir->kobj.ktype = dir->kobj.ktype;
 409                         ret = kobject_set_name(&subdir->kobj, "%s", tok);
 410                         if (ret) {
 411                                 kfree(subdir);
 412                                 break;
 413                         }
 414                         ret = kset_register(subdir);
 415                         if (ret) {
 416                                 kfree(subdir);
 417                                 break;
 418                         }
 419
 420                         /* descend into newly created subdirectory */
 421                         dir = subdir;
 422                 }
 423         }
 424
 425         /* we're done with cloned copy of name */
 426         kfree(name_copy);
 427         return ret;
 428 }
 429
 430 /* recursively unregister fw_cfg/by_name/ kset directory tree */
 431 static void fw_cfg_kset_unregister_recursive(struct kset *kset)
 432 {
 433         struct kobject *k, *next;
 434
 435         list_for_each_entry_safe(k, next, &kset->list, entry)
 436                 /* all set members are ksets too, but check just in case... */
 437                 if (k->ktype == kset->kobj.ktype)
 438                         fw_cfg_kset_unregister_recursive(to_kset(k));
 439
 440         /* symlinks are cleanly and automatically removed with the directory */
 441         kset_unregister(kset);
 442 }
 443
 444 /* kobjects & kset representing top-level, by_key, and by_name folders */
 445 static struct kobject *fw_cfg_top_ko;
 446 static struct kobject *fw_cfg_sel_ko;
 447 static struct kset *fw_cfg_fname_kset;
 448
 449 /* register an individual fw_cfg file */
 450 static int fw_cfg_register_file(const struct fw_cfg_file *f)
 451 {
 452         int err;
 453         struct fw_cfg_sysfs_entry *entry;
 454
 455         /* allocate new entry */
 456         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 457         if (!entry)
 458                 return -ENOMEM;
 459
 460         /* set file entry information */
 461         memcpy(&entry->f, f, sizeof(struct fw_cfg_file));
 462
 463         /* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
 464         err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
 465                                    fw_cfg_sel_ko, "%d", entry->f.select);
 466         if (err)
 467                 goto err_register;
 468
 469         /* add raw binary content access */
 470         err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
 471         if (err)
 472                 goto err_add_raw;
 473
 474         /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
 475         fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->f.name);
 476
 477         /* success, add entry to global cache */
 478         fw_cfg_sysfs_cache_enlist(entry);
 479         return 0;
 480
 481 err_add_raw:
 482         kobject_del(&entry->kobj);
 483 err_register:
 484         kfree(entry);
 485         return err;
 486 }
 487
 488 /* iterate over all fw_cfg directory entries, registering each one */
 489 static int fw_cfg_register_dir_entries(void)
 490 {
 491         int ret = 0;
 492         u32 count, i;
 493         struct fw_cfg_file *dir;
 494         size_t dir_size;
 495
 496         fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count));
 497         count = be32_to_cpu(count);
 498         dir_size = count * sizeof(struct fw_cfg_file);
 499
 500         dir = kmalloc(dir_size, GFP_KERNEL);
 501         if (!dir)
 502                 return -ENOMEM;
 503
 504         fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size);
 505
 506         for (i = 0; i < count; i++) {
 507                 dir[i].size = be32_to_cpu(dir[i].size);
 508                 dir[i].select = be16_to_cpu(dir[i].select);
 509                 ret = fw_cfg_register_file(&dir[i]);
 510                 if (ret)
 511                         break;
 512         }
 513
 514         kfree(dir);
 515         return ret;
 516 }
 517
 518 /* unregister top-level or by_key folder */
 519 static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
 520 {
 521         kobject_del(kobj);
 522         kobject_put(kobj);
 523 }
 524
 525 static int fw_cfg_sysfs_probe(struct platform_device *pdev)
 526 {
 527         int err;
 528
 529         /* NOTE: If we supported multiple fw_cfg devices, we'd first create
 530          * a subdirectory named after e.g. pdev->id, then hang per-device
 531          * by_key (and by_name) subdirectories underneath it. However, only
 532          * one fw_cfg device exist system-wide, so if one was already found
 533          * earlier, we might as well stop here.
 534          */
 535         if (fw_cfg_sel_ko)
 536                 return -EBUSY;
 537
 538         /* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
 539         err = -ENOMEM;
 540         fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
 541         if (!fw_cfg_sel_ko)
 542                 goto err_sel;
 543         fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
 544         if (!fw_cfg_fname_kset)
 545                 goto err_name;
 546
 547         /* initialize fw_cfg device i/o from platform data */
 548         err = fw_cfg_do_platform_probe(pdev);
 549         if (err)
 550                 goto err_probe;
 551
 552         /* get revision number, add matching top-level attribute */
 553         fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev));
 554         fw_cfg_rev = le32_to_cpu(fw_cfg_rev);
 555         err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 556         if (err)
 557                 goto err_rev;
 558
 559         /* process fw_cfg file directory entry, registering each file */
 560         err = fw_cfg_register_dir_entries();
 561         if (err)
 562                 goto err_dir;
 563
 564         /* success */
 565         pr_debug("fw_cfg: loaded.\n");
 566         return 0;
 567
 568 err_dir:
 569         fw_cfg_sysfs_cache_cleanup();
 570         sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
 571 err_rev:
 572         fw_cfg_io_cleanup();
 573 err_probe:
 574         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 575 err_name:
 576         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 577 err_sel:
 578         return err;
 579 }
 580
 581 static int fw_cfg_sysfs_remove(struct platform_device *pdev)
 582 {
 583         pr_debug("fw_cfg: unloading.\n");
 584         fw_cfg_sysfs_cache_cleanup();
 585         fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 586         fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
 587         fw_cfg_io_cleanup();
 588         return 0;
 589 }
 590
 591 static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
 592         { .compatible = "qemu,fw-cfg-mmio", },
 593         {},
 594 };
 595 MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);
 596
 597 #ifdef CONFIG_ACPI
 598 static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {
 599         { "QEMU0002", },
 600         {},
 601 };
 602 MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
 603 #endif
 604
 605 static struct platform_driver fw_cfg_sysfs_driver = {
 606         .probe = fw_cfg_sysfs_probe,
 607         .remove = fw_cfg_sysfs_remove,
 608         .driver = {
 609                 .name = "fw_cfg",
 610                 .of_match_table = fw_cfg_sysfs_mmio_match,
 611                 .acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),
 612         },
 613 };
 614
 615 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
 616
 617 static struct platform_device *fw_cfg_cmdline_dev;
 618
 619 /* this probably belongs in e.g. include/linux/types.h,
 620  * but right now we are the only ones doing it...
 621  */
 622 #ifdef CONFIG_PHYS_ADDR_T_64BIT
 623 #define __PHYS_ADDR_PREFIX "ll"
 624 #else
 625 #define __PHYS_ADDR_PREFIX ""
 626 #endif
 627
 628 /* use special scanf/printf modifier for phys_addr_t, resource_size_t */
 629 #define PH_ADDR_SCAN_FMT "@%" __PHYS_ADDR_PREFIX "i%n" \
 630                          ":%" __PHYS_ADDR_PREFIX "i" \
 631                          ":%" __PHYS_ADDR_PREFIX "i%n"
 632
 633 #define PH_ADDR_PR_1_FMT "0x%" __PHYS_ADDR_PREFIX "x@" \
 634                          "0x%" __PHYS_ADDR_PREFIX "x"
 635
 636 #define PH_ADDR_PR_3_FMT PH_ADDR_PR_1_FMT \
 637                          ":%" __PHYS_ADDR_PREFIX "u" \
 638                          ":%" __PHYS_ADDR_PREFIX "u"
 639
 640 static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)
 641 {
 642         struct resource res[3] = {};
 643         char *str;
 644         phys_addr_t base;
 645         resource_size_t size, ctrl_off, data_off;
 646         int processed, consumed = 0;
 647
 648         /* only one fw_cfg device can exist system-wide, so if one
 649          * was processed on the command line already, we might as
 650          * well stop here.
 651          */
 652         if (fw_cfg_cmdline_dev) {
 653                 /* avoid leaking previously registered device */
 654                 platform_device_unregister(fw_cfg_cmdline_dev);
 655                 return -EINVAL;
 656         }
 657
 658         /* consume "<size>" portion of command line argument */
 659         size = memparse(arg, &str);
 660
 661         /* get "@<base>[:<ctrl_off>:<data_off>]" chunks */
 662         processed = sscanf(str, PH_ADDR_SCAN_FMT,
 663                            &base, &consumed,
 664                            &ctrl_off, &data_off, &consumed);
 665
 666         /* sscanf() must process precisely 1 or 3 chunks:
 667          * <base> is mandatory, optionally followed by <ctrl_off>
 668          * and <data_off>;
 669          * there must be no extra characters after the last chunk,
 670          * so str[consumed] must be '\0'.
 671          */
 672         if (str[consumed] ||
 673             (processed != 1 && processed != 3))
 674                 return -EINVAL;
 675
 676         res[0].start = base;
 677         res[0].end = base + size - 1;
 678         res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :
 679                                                    IORESOURCE_IO;
 680
 681         /* insert register offsets, if provided */
 682         if (processed > 1) {
 683                 res[1].name = "ctrl";
 684                 res[1].start = ctrl_off;
 685                 res[1].flags = IORESOURCE_REG;
 686                 res[2].name = "data";
 687                 res[2].start = data_off;
 688                 res[2].flags = IORESOURCE_REG;
 689         }
 690
 691         /* "processed" happens to nicely match the number of resources
 692          * we need to pass in to this platform device.
 693          */
 694         fw_cfg_cmdline_dev = platform_device_register_simple("fw_cfg",
 695                                         PLATFORM_DEVID_NONE, res, processed);
 696         if (IS_ERR(fw_cfg_cmdline_dev))
 697                 return PTR_ERR(fw_cfg_cmdline_dev);
 698
 699         return 0;
 700 }
 701
 702 static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)
 703 {
 704         /* stay silent if device was not configured via the command
 705          * line, or if the parameter name (ioport/mmio) doesn't match
 706          * the device setting
 707          */
 708         if (!fw_cfg_cmdline_dev ||
 709             (!strcmp(kp->name, "mmio") ^
 710              (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))
 711                 return 0;
 712
 713         switch (fw_cfg_cmdline_dev->num_resources) {
 714         case 1:
 715                 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_1_FMT,
 716                                 resource_size(&fw_cfg_cmdline_dev->resource[0]),
 717                                 fw_cfg_cmdline_dev->resource[0].start);
 718         case 3:
 719                 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_3_FMT,
 720                                 resource_size(&fw_cfg_cmdline_dev->resource[0]),
 721                                 fw_cfg_cmdline_dev->resource[0].start,
 722                                 fw_cfg_cmdline_dev->resource[1].start,
 723                                 fw_cfg_cmdline_dev->resource[2].start);
 724         }
 725
 726         /* Should never get here */
 727         WARN(1, "Unexpected number of resources: %d\n",
 728                 fw_cfg_cmdline_dev->num_resources);
 729         return 0;
 730 }
 731
 732 static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {
 733         .set = fw_cfg_cmdline_set,
 734         .get = fw_cfg_cmdline_get,
 735 };
 736
 737 device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 738 device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
 739
 740 #endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */
 741
 742 static int __init fw_cfg_sysfs_init(void)
 743 {
 744         int ret;
 745
 746         /* create /sys/firmware/qemu_fw_cfg/ top level directory */
 747         fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
 748         if (!fw_cfg_top_ko)
 749                 return -ENOMEM;
 750
 751         ret = platform_driver_register(&fw_cfg_sysfs_driver);
 752         if (ret)
 753                 fw_cfg_kobj_cleanup(fw_cfg_top_ko);
 754
 755         return ret;
 756 }
 757
 758 static void __exit fw_cfg_sysfs_exit(void)
 759 {
 760         platform_driver_unregister(&fw_cfg_sysfs_driver);
 761
 762 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
 763         platform_device_unregister(fw_cfg_cmdline_dev);
 764 #endif
 765
 766         /* clean up /sys/firmware/qemu_fw_cfg/ */
 767         fw_cfg_kobj_cleanup(fw_cfg_top_ko);
 768 }
 769
 770 module_init(fw_cfg_sysfs_init);
 771 module_exit(fw_cfg_sysfs_exit);