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