target/linux/generic/files/drivers/platform/mikrotik/rb_softconfig.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for MikroTik RouterBoot soft config.
   4  *
   5  * Copyright (C) 2020 Thibaut VARÈNE <hacks+kernel@slashdirt.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published
   9  * by the Free Software Foundation.
  10  *
  11  * This driver exposes the data encoded in the "soft_config" flash segment of
  12  * MikroTik RouterBOARDs devices. It presents the data in a sysfs folder
  13  * named "soft_config". The data is presented in a user/machine-friendly way
  14  * with just as much parsing as can be generalized across mikrotik platforms
  15  * (as inferred from reverse-engineering).
  16  *
  17  * The known soft_config tags are presented in the "soft_config" sysfs folder,
  18  * with the addition of one specific file named "commit", which is only
  19  * available if the driver supports writes to the mtd device: no modifications
  20  * made to any of the other attributes are actually written back to flash media
  21  * until a true value is input into this file (e.g. [Yy1]). This is to avoid
  22  * unnecessary flash wear, and to permit to revert all changes by issuing a
  23  * false value ([Nn0]). Reading the content of this file shows the current
  24  * status of the driver: if the data in sysfs matches the content of the
  25  * soft_config partition, the file will read "clean". Otherwise, it will read
  26  * "dirty".
  27  *
  28  * The writeable sysfs files presented by this driver will accept only inputs
  29  * which are in a valid range for the given tag. As a design choice, the driver
  30  * will not assess whether the inputs are identical to the existing data.
  31  *
  32  * Note: PAGE_SIZE is assumed to be >= 4K, hence the device attribute show
  33  * routines need not check for output overflow.
  34  *
  35  * Some constant defines extracted from rbcfg.h by Gabor Juhos
  36  * <juhosg@openwrt.org>
  37  */
  38
  39 #include <linux/types.h>
  40 #include <linux/init.h>
  41 #include <linux/kernel.h>
  42 #include <linux/slab.h>
  43 #include <linux/errno.h>
  44 #include <linux/kobject.h>
  45 #include <linux/string.h>
  46 #include <linux/mtd/mtd.h>
  47 #include <linux/sysfs.h>
  48 #include <linux/version.h>
  49 #include <linux/capability.h>
  50 #include <linux/spinlock.h>
  51 #include <linux/crc32.h>
  52
  53 #ifdef CONFIG_ATH79
  54  #include <asm/mach-ath79/ath79.h>
  55 #endif
  56
  57 #include "routerboot.h"
  58
  59 #define RB_SOFTCONFIG_VER               "0.02"
  60 #define RB_SC_PR_PFX                    "[rb_softconfig] "
  61
  62 /*
  63  * mtd operations before 4.17 are asynchronous, not handled by this code
  64  * Also make the driver act read-only if 4K_SECTORS are not enabled, since they
  65  * are require to handle partial erasing of the small soft_config partition.
  66  */
  67 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 17, 0)) && defined(CONFIG_MTD_SPI_NOR_USE_4K_SECTORS)
  68  #define RB_SC_HAS_WRITE_SUPPORT        true
  69  #define RB_SC_WMODE                    S_IWUSR
  70  #define RB_SC_RMODE                    S_IRUSR
  71 #else
  72  #define RB_SC_HAS_WRITE_SUPPORT        false
  73  #define RB_SC_WMODE                    0
  74  #define RB_SC_RMODE                    S_IRUSR
  75 #endif
  76
  77 /* ID values for software settings */
  78 #define RB_SCID_UART_SPEED              0x01    // u32*1
  79 #define RB_SCID_BOOT_DELAY              0x02    // u32*1
  80 #define RB_SCID_BOOT_DEVICE             0x03    // u32*1
  81 #define RB_SCID_BOOT_KEY                0x04    // u32*1
  82 #define RB_SCID_CPU_MODE                0x05    // u32*1
  83 #define RB_SCID_BIOS_VERSION            0x06    // str
  84 #define RB_SCID_BOOT_PROTOCOL           0x09    // u32*1
  85 #define RB_SCID_CPU_FREQ_IDX            0x0C    // u32*1
  86 #define RB_SCID_BOOTER                  0x0D    // u32*1
  87 #define RB_SCID_SILENT_BOOT             0x0F    // u32*1
  88 /*
  89  * protected_routerboot seems to use tag 0x1F. It only works in combination with
  90  * RouterOS, resulting in a wiped board otherwise, so it's not implemented here.
  91  * The tag values are as follows:
  92  * - off: 0x0
  93  * - on: the lower halfword encodes the max value in s for the reset feature,
  94  *       the higher halfword encodes the min value in s for the reset feature.
  95  * Default value when on: 0x00140258: 0x14 = 20s / 0x258= 600s
  96  * See details here: https://wiki.mikrotik.com/wiki/Manual:RouterBOARD_settings#Protected_bootloader
  97  */
  98
  99 /* Tag values */
 100
 101 #define RB_UART_SPEED_115200            0
 102 #define RB_UART_SPEED_57600             1
 103 #define RB_UART_SPEED_38400             2
 104 #define RB_UART_SPEED_19200             3
 105 #define RB_UART_SPEED_9600              4
 106 #define RB_UART_SPEED_4800              5
 107 #define RB_UART_SPEED_2400              6
 108 #define RB_UART_SPEED_1200              7
 109 #define RB_UART_SPEED_OFF               8
 110
 111 /* valid boot delay: 1 - 9s in 1s increment */
 112 #define RB_BOOT_DELAY_MIN               1
 113 #define RB_BOOT_DELAY_MAX               9
 114
 115 #define RB_BOOT_DEVICE_ETHER            0       // "boot over Ethernet"
 116 #define RB_BOOT_DEVICE_NANDETH          1       // "boot from NAND, if fail then Ethernet"
 117 #define RB_BOOT_DEVICE_CFCARD           2       // (not available in rbcfg)
 118 #define RB_BOOT_DEVICE_ETHONCE          3       // "boot Ethernet once, then NAND"
 119 #define RB_BOOT_DEVICE_NANDONLY         5       // "boot from NAND only"
 120 #define RB_BOOT_DEVICE_FLASHCFG         7       // "boot in flash configuration mode"
 121 #define RB_BOOT_DEVICE_FLSHONCE         8       // "boot in flash configuration mode once, then NAND"
 122
 123 /*
 124  * ATH79 CPU frequency indices.
 125  * It is unknown if they apply to all ATH79 RBs, and some do not seem to feature
 126  * the up levels (QCA955x), while U3 is presumably AR9344-only.
 127  */
 128 #define RB_CPU_FREQ_IDX_ATH79_D2        (0 << 3)
 129 #define RB_CPU_FREQ_IDX_ATH79_D1        (1 << 3)        // 0x8
 130 #define RB_CPU_FREQ_IDX_ATH79_N0        (2 << 3)        // 0x10 - factory freq for many devices
 131 #define RB_CPU_FREQ_IDX_ATH79_U1        (3 << 3)        // 0x18
 132 #define RB_CPU_FREQ_IDX_ATH79_U2        (4 << 3)        // 0x20
 133 #define RB_CPU_FREQ_IDX_ATH79_U3        (5 << 3)        // 0x28
 134
 135 #define RB_CPU_FREQ_IDX_ATH79_MIN               0       // all devices support lowest setting
 136 #define RB_CPU_FREQ_IDX_ATH79_AR9334_MAX        5       // stops at U3
 137 #define RB_CPU_FREQ_IDX_ATH79_QCA953X_MAX       4       // stops at U2
 138 #define RB_CPU_FREQ_IDX_ATH79_QCA9556_MAX       2       // stops at N0
 139 #define RB_CPU_FREQ_IDX_ATH79_QCA9558_MAX       3       // stops at U1
 140
 141 #define RB_SC_CRC32_OFFSET              4       // located right after magic
 142
 143 static struct kobject *sc_kobj;
 144 static u8 *sc_buf;
 145 static size_t sc_buflen;
 146 static rwlock_t sc_bufrwl;              // rw lock to sc_buf
 147
 148 /* MUST be used with lock held */
 149 #define RB_SC_CLRCRC()          *(u32 *)(sc_buf + RB_SC_CRC32_OFFSET) = 0
 150 #define RB_SC_GETCRC()          *(u32 *)(sc_buf + RB_SC_CRC32_OFFSET)
 151 #define RB_SC_SETCRC(_crc)      *(u32 *)(sc_buf + RB_SC_CRC32_OFFSET) = (_crc)
 152
 153 struct sc_u32tvs {
 154         const u32 val;
 155         const char *str;
 156 };
 157
 158 #define RB_SC_TVS(_val, _str) {         \
 159         .val = (_val),                  \
 160         .str = (_str),                  \
 161 }
 162
 163 static ssize_t sc_tag_show_u32tvs(const u8 *pld, u16 pld_len, char *buf,
 164                                   const struct sc_u32tvs tvs[], const int tvselmts)
 165 {
 166         const char *fmt;
 167         char *out = buf;
 168         u32 data;       // cpu-endian
 169         int i;
 170
 171         if (tvselmts < 0)
 172                 return tvselmts;
 173
 174         if (sizeof(data) != pld_len)
 175                 return -EINVAL;
 176
 177         read_lock(&sc_bufrwl);
 178         data = *(u32 *)pld;             // pld aliases sc_buf
 179         read_unlock(&sc_bufrwl);
 180
 181         for (i = 0; i < tvselmts; i++) {
 182                 fmt = (tvs[i].val == data) ? "[%s] " : "%s ";
 183                 out += sprintf(out, fmt, tvs[i].str);
 184         }
 185
 186         out += sprintf(out, "\n");
 187         return out - buf;
 188 }
 189
 190 static ssize_t sc_tag_store_u32tvs(const u8 *pld, u16 pld_len, const char *buf, size_t count,
 191                                    const struct sc_u32tvs tvs[], const int tvselmts)
 192 {
 193         int i;
 194
 195         if (tvselmts < 0)
 196                 return tvselmts;
 197
 198         if (sizeof(u32) != pld_len)
 199                 return -EINVAL;
 200
 201         for (i = 0; i < tvselmts; i++) {
 202                 if (sysfs_streq(buf, tvs[i].str)) {
 203                         write_lock(&sc_bufrwl);
 204                         *(u32 *)pld = tvs[i].val;       // pld aliases sc_buf
 205                         RB_SC_CLRCRC();
 206                         write_unlock(&sc_bufrwl);
 207                         return count;
 208                 }
 209         }
 210
 211         return -EINVAL;
 212 }
 213
 214 struct sc_boolts {
 215         const char *strfalse;
 216         const char *strtrue;
 217 };
 218
 219 static ssize_t sc_tag_show_boolts(const u8 *pld, u16 pld_len, char *buf,
 220                                   const struct sc_boolts *bts)
 221 {
 222         const char *fmt;
 223         char *out = buf;
 224         u32 data;       // cpu-endian
 225
 226         if (sizeof(data) != pld_len)
 227                 return -EINVAL;
 228
 229         read_lock(&sc_bufrwl);
 230         data = *(u32 *)pld;             // pld aliases sc_buf
 231         read_unlock(&sc_bufrwl);
 232
 233         fmt = (data) ? "%s [%s]\n" : "[%s] %s\n";
 234         out += sprintf(out, fmt, bts->strfalse, bts->strtrue);
 235
 236         return out - buf;
 237 }
 238
 239 static ssize_t sc_tag_store_boolts(const u8 *pld, u16 pld_len, const char *buf, size_t count,
 240                                    const struct sc_boolts *bts)
 241 {
 242         u32 data;       // cpu-endian
 243
 244         if (sizeof(data) != pld_len)
 245                 return -EINVAL;
 246
 247         if (sysfs_streq(buf, bts->strfalse))
 248                 data = 0;
 249         else if (sysfs_streq(buf, bts->strtrue))
 250                 data = 1;
 251         else
 252                 return -EINVAL;
 253
 254         write_lock(&sc_bufrwl);
 255         *(u32 *)pld = data;             // pld aliases sc_buf
 256         RB_SC_CLRCRC();
 257         write_unlock(&sc_bufrwl);
 258
 259         return count;
 260 }
 261 static struct sc_u32tvs const sc_uartspeeds[] = {
 262         RB_SC_TVS(RB_UART_SPEED_OFF,    "off"),
 263         RB_SC_TVS(RB_UART_SPEED_1200,   "1200"),
 264         RB_SC_TVS(RB_UART_SPEED_2400,   "2400"),
 265         RB_SC_TVS(RB_UART_SPEED_4800,   "4800"),
 266         RB_SC_TVS(RB_UART_SPEED_9600,   "9600"),
 267         RB_SC_TVS(RB_UART_SPEED_19200,  "19200"),
 268         RB_SC_TVS(RB_UART_SPEED_38400,  "38400"),
 269         RB_SC_TVS(RB_UART_SPEED_57600,  "57600"),
 270         RB_SC_TVS(RB_UART_SPEED_115200, "115200"),
 271 };
 272
 273 /*
 274  * While the defines are carried over from rbcfg, use strings that more clearly
 275  * show the actual setting purpose (especially since the NAND* settings apply
 276  * to both nand- and nor-based devices). "cfcard" was disabled in rbcfg: disable
 277  * it here too.
 278  */
 279 static struct sc_u32tvs const sc_bootdevices[] = {
 280         RB_SC_TVS(RB_BOOT_DEVICE_ETHER,         "eth"),
 281         RB_SC_TVS(RB_BOOT_DEVICE_NANDETH,       "flasheth"),
 282         //RB_SC_TVS(RB_BOOT_DEVICE_CFCARD,      "cfcard"),
 283         RB_SC_TVS(RB_BOOT_DEVICE_ETHONCE,       "ethonce"),
 284         RB_SC_TVS(RB_BOOT_DEVICE_NANDONLY,      "flash"),
 285         RB_SC_TVS(RB_BOOT_DEVICE_FLASHCFG,      "cfg"),
 286         RB_SC_TVS(RB_BOOT_DEVICE_FLSHONCE,      "cfgonce"),
 287 };
 288
 289 static struct sc_boolts const sc_bootkey = {
 290         .strfalse = "any",
 291         .strtrue = "del",
 292 };
 293
 294 static struct sc_boolts const sc_cpumode = {
 295         .strfalse = "powersave",
 296         .strtrue = "regular",
 297 };
 298
 299 static struct sc_boolts const sc_bootproto = {
 300         .strfalse = "bootp",
 301         .strtrue = "dhcp",
 302 };
 303
 304 static struct sc_boolts const sc_booter = {
 305         .strfalse = "regular",
 306         .strtrue = "backup",
 307 };
 308
 309 static struct sc_boolts const sc_silent_boot = {
 310         .strfalse = "off",
 311         .strtrue = "on",
 312 };
 313
 314 #define SC_TAG_SHOW_STORE_U32TVS_FUNCS(_name)           \
 315 static ssize_t sc_tag_show_##_name(const u8 *pld, u16 pld_len, char *buf)       \
 316 {                                                                               \
 317         return sc_tag_show_u32tvs(pld, pld_len, buf, sc_##_name, ARRAY_SIZE(sc_##_name));       \
 318 }                                                                               \
 319 static ssize_t sc_tag_store_##_name(const u8 *pld, u16 pld_len, const char *buf, size_t count)  \
 320 {                                                                               \
 321         return sc_tag_store_u32tvs(pld, pld_len, buf, count, sc_##_name, ARRAY_SIZE(sc_##_name));       \
 322 }
 323
 324 #define SC_TAG_SHOW_STORE_BOOLTS_FUNCS(_name)           \
 325 static ssize_t sc_tag_show_##_name(const u8 *pld, u16 pld_len, char *buf)       \
 326 {                                                                               \
 327         return sc_tag_show_boolts(pld, pld_len, buf, &sc_##_name);      \
 328 }                                                                               \
 329 static ssize_t sc_tag_store_##_name(const u8 *pld, u16 pld_len, const char *buf, size_t count)  \
 330 {                                                                               \
 331         return sc_tag_store_boolts(pld, pld_len, buf, count, &sc_##_name);      \
 332 }
 333
 334 SC_TAG_SHOW_STORE_U32TVS_FUNCS(uartspeeds)
 335 SC_TAG_SHOW_STORE_U32TVS_FUNCS(bootdevices)
 336 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(bootkey)
 337 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(cpumode)
 338 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(bootproto)
 339 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(booter)
 340 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(silent_boot)
 341
 342 static ssize_t sc_tag_show_bootdelays(const u8 *pld, u16 pld_len, char *buf)
 343 {
 344         const char *fmt;
 345         char *out = buf;
 346         u32 data;       // cpu-endian
 347         int i;
 348
 349         if (sizeof(data) != pld_len)
 350                 return -EINVAL;
 351
 352         read_lock(&sc_bufrwl);
 353         data = *(u32 *)pld;             // pld aliases sc_buf
 354         read_unlock(&sc_bufrwl);
 355
 356         for (i = RB_BOOT_DELAY_MIN; i <= RB_BOOT_DELAY_MAX; i++) {
 357                 fmt = (i == data) ? "[%d] " : "%d ";
 358                 out += sprintf(out, fmt, i);
 359         }
 360
 361         out += sprintf(out, "\n");
 362         return out - buf;
 363 }
 364
 365 static ssize_t sc_tag_store_bootdelays(const u8 *pld, u16 pld_len, const char *buf, size_t count)
 366 {
 367         u32 data;       // cpu-endian
 368         int ret;
 369
 370         if (sizeof(data) != pld_len)
 371                 return -EINVAL;
 372
 373         ret = kstrtou32(buf, 10, &data);
 374         if (ret)
 375                 return ret;
 376
 377         if ((data < RB_BOOT_DELAY_MIN) || (RB_BOOT_DELAY_MAX < data))
 378                 return -EINVAL;
 379
 380         write_lock(&sc_bufrwl);
 381         *(u32 *)pld = data;             // pld aliases sc_buf
 382         RB_SC_CLRCRC();
 383         write_unlock(&sc_bufrwl);
 384
 385         return count;
 386 }
 387
 388 /* Support CPU frequency accessors only when the tag format has been asserted */
 389 #if defined(CONFIG_ATH79)
 390 static struct sc_u32tvs const sc_cpufreq_indexes_ath79[] = {
 391         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_D2,     "-2"),
 392         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_D1,     "-1"),
 393         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_N0,     "0"),
 394         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_U1,     "+1"),
 395         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_U2,     "+2"),
 396         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_U3,     "+3"),
 397 };
 398
 399 static int sc_tag_cpufreq_ath79_idxmax(void)
 400 {
 401         int idx_max = -EOPNOTSUPP;
 402
 403         if (soc_is_ar9344())
 404                 idx_max = RB_CPU_FREQ_IDX_ATH79_AR9334_MAX;
 405         else if (soc_is_qca953x())
 406                 idx_max = RB_CPU_FREQ_IDX_ATH79_QCA953X_MAX;
 407         else if (soc_is_qca9556())
 408                 idx_max = RB_CPU_FREQ_IDX_ATH79_QCA9556_MAX;
 409         else if (soc_is_qca9558())
 410                 idx_max = RB_CPU_FREQ_IDX_ATH79_QCA9558_MAX;
 411
 412         return idx_max;
 413 }
 414
 415 static ssize_t sc_tag_show_cpufreq_indexes(const u8 *pld, u16 pld_len, char * buf)
 416 {
 417         return sc_tag_show_u32tvs(pld, pld_len, buf, sc_cpufreq_indexes_ath79, sc_tag_cpufreq_ath79_idxmax()+1);
 418 }
 419
 420 static ssize_t sc_tag_store_cpufreq_indexes(const u8 *pld, u16 pld_len, const char *buf, size_t count)
 421 {
 422         return sc_tag_store_u32tvs(pld, pld_len, buf, count, sc_cpufreq_indexes_ath79, sc_tag_cpufreq_ath79_idxmax()+1);
 423 }
 424 #else
 425  /* By default we only show the raw value to help with reverse-engineering */
 426  #define sc_tag_show_cpufreq_indexes    routerboot_tag_show_u32s
 427  #define sc_tag_store_cpufreq_indexes   NULL
 428 #endif
 429
 430 static ssize_t sc_attr_show(struct kobject *kobj, struct kobj_attribute *attr,
 431                             char *buf);
 432 static ssize_t sc_attr_store(struct kobject *kobj, struct kobj_attribute *attr,
 433                              const char *buf, size_t count);
 434
 435 /* Array of known tags to publish in sysfs */
 436 static struct sc_attr {
 437         const u16 tag_id;
 438         /* sysfs tag show attribute. Must lock sc_buf when dereferencing pld */
 439         ssize_t (* const tshow)(const u8 *pld, u16 pld_len, char *buf);
 440         /* sysfs tag store attribute. Must lock sc_buf when dereferencing pld */
 441         ssize_t (* const tstore)(const u8 *pld, u16 pld_len, const char *buf, size_t count);
 442         struct kobj_attribute kattr;
 443         u16 pld_ofs;
 444         u16 pld_len;
 445 } sc_attrs[] = {
 446         {
 447                 .tag_id = RB_SCID_UART_SPEED,
 448                 .tshow = sc_tag_show_uartspeeds,
 449                 .tstore = sc_tag_store_uartspeeds,
 450                 .kattr = __ATTR(uart_speed, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 451         }, {
 452                 .tag_id = RB_SCID_BOOT_DELAY,
 453                 .tshow = sc_tag_show_bootdelays,
 454                 .tstore = sc_tag_store_bootdelays,
 455                 .kattr = __ATTR(boot_delay, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 456         }, {
 457                 .tag_id = RB_SCID_BOOT_DEVICE,
 458                 .tshow = sc_tag_show_bootdevices,
 459                 .tstore = sc_tag_store_bootdevices,
 460                 .kattr = __ATTR(boot_device, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 461         }, {
 462                 .tag_id = RB_SCID_BOOT_KEY,
 463                 .tshow = sc_tag_show_bootkey,
 464                 .tstore = sc_tag_store_bootkey,
 465                 .kattr = __ATTR(boot_key, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 466         }, {
 467                 .tag_id = RB_SCID_CPU_MODE,
 468                 .tshow = sc_tag_show_cpumode,
 469                 .tstore = sc_tag_store_cpumode,
 470                 .kattr = __ATTR(cpu_mode, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 471         }, {
 472                 .tag_id = RB_SCID_BIOS_VERSION,
 473                 .tshow = routerboot_tag_show_string,
 474                 .tstore = NULL,
 475                 .kattr = __ATTR(bios_version, RB_SC_RMODE, sc_attr_show, NULL),
 476         }, {
 477                 .tag_id = RB_SCID_BOOT_PROTOCOL,
 478                 .tshow = sc_tag_show_bootproto,
 479                 .tstore = sc_tag_store_bootproto,
 480                 .kattr = __ATTR(boot_proto, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 481         }, {
 482                 .tag_id = RB_SCID_CPU_FREQ_IDX,
 483                 .tshow = sc_tag_show_cpufreq_indexes,
 484                 .tstore = sc_tag_store_cpufreq_indexes,
 485                 .kattr = __ATTR(cpufreq_index, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 486         }, {
 487                 .tag_id = RB_SCID_BOOTER,
 488                 .tshow = sc_tag_show_booter,
 489                 .tstore = sc_tag_store_booter,
 490                 .kattr = __ATTR(booter, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 491         }, {
 492                 .tag_id = RB_SCID_SILENT_BOOT,
 493                 .tshow = sc_tag_show_silent_boot,
 494                 .tstore = sc_tag_store_silent_boot,
 495                 .kattr = __ATTR(silent_boot, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 496         },
 497 };
 498
 499 static ssize_t sc_attr_show(struct kobject *kobj, struct kobj_attribute *attr,
 500                             char *buf)
 501 {
 502         const struct sc_attr *sc_attr;
 503         const u8 *pld;
 504         u16 pld_len;
 505
 506         sc_attr = container_of(attr, typeof(*sc_attr), kattr);
 507
 508         if (!sc_attr->pld_len)
 509                 return -ENOENT;
 510
 511         pld = sc_buf + sc_attr->pld_ofs;        // pld aliases sc_buf -> lock!
 512         pld_len = sc_attr->pld_len;
 513
 514         return sc_attr->tshow(pld, pld_len, buf);
 515 }
 516
 517 static ssize_t sc_attr_store(struct kobject *kobj, struct kobj_attribute *attr,
 518                              const char *buf, size_t count)
 519 {
 520         const struct sc_attr *sc_attr;
 521         const u8 *pld;
 522         u16 pld_len;
 523
 524         if (!RB_SC_HAS_WRITE_SUPPORT)
 525                 return -EOPNOTSUPP;
 526
 527         if (!capable(CAP_SYS_ADMIN))
 528                 return -EACCES;
 529
 530         sc_attr = container_of(attr, typeof(*sc_attr), kattr);
 531
 532         if (!sc_attr->tstore)
 533                 return -EOPNOTSUPP;
 534
 535         if (!sc_attr->pld_len)
 536                 return -ENOENT;
 537
 538         pld = sc_buf + sc_attr->pld_ofs;        // pld aliases sc_buf -> lock!
 539         pld_len = sc_attr->pld_len;
 540
 541         return sc_attr->tstore(pld, pld_len, buf, count);
 542 }
 543
 544 /*
 545  * Shows the current buffer status:
 546  * "clean": the buffer is in sync with the mtd data
 547  * "dirty": the buffer is out of sync with the mtd data
 548  */
 549 static ssize_t sc_commit_show(struct kobject *kobj, struct kobj_attribute *attr,
 550                               char *buf)
 551 {
 552         const char *str;
 553         char *out = buf;
 554         u32 crc;
 555
 556         read_lock(&sc_bufrwl);
 557         crc = RB_SC_GETCRC();
 558         read_unlock(&sc_bufrwl);
 559
 560         str = (crc) ? "clean" : "dirty";
 561         out += sprintf(out, "%s\n", str);
 562
 563         return out - buf;
 564 }
 565
 566 /*
 567  * Performs buffer flushing:
 568  * This routine expects an input compatible with kstrtobool().
 569  * - a "false" input discards the current changes and reads data back from mtd.
 570  * - a "true" input commits the current changes to mtd.
 571  * If there is no pending changes, this routine is a no-op.
 572  * Handling failures is left as an exercise to userspace.
 573  */
 574 static ssize_t sc_commit_store(struct kobject *kobj, struct kobj_attribute *attr,
 575                               const char *buf, size_t count)
 576 {
 577         struct mtd_info *mtd;
 578         struct erase_info ei;
 579         size_t bytes_rw, ret = count;
 580         bool flush;
 581         u32 crc;
 582
 583         if (!RB_SC_HAS_WRITE_SUPPORT)
 584                 return -EOPNOTSUPP;
 585
 586         read_lock(&sc_bufrwl);
 587         crc = RB_SC_GETCRC();
 588         read_unlock(&sc_bufrwl);
 589
 590         if (crc)
 591                 return count;   // NO-OP
 592
 593         ret = kstrtobool(buf, &flush);
 594         if (ret)
 595                 return ret;
 596
 597         mtd = get_mtd_device_nm(RB_MTD_SOFT_CONFIG);    // TODO allow override
 598         if (IS_ERR(mtd))
 599                 return -ENODEV;
 600
 601         write_lock(&sc_bufrwl);
 602         if (!flush)     // reread
 603                 ret = mtd_read(mtd, 0, mtd->size, &bytes_rw, sc_buf);
 604         else {  // crc32 + commit
 605                 /*
 606                  * CRC32 is computed on the entire buffer, excluding the CRC
 607                  * value itself. CRC is already null when we reach this point,
 608                  * so we can compute the CRC32 on the buffer as is.
 609                  * The expected CRC32 is Ethernet FCS style, meaning the seed is
 610                  * ~0 and the final result is also bitflipped.
 611                  */
 612
 613                 crc = ~crc32(~0, sc_buf, sc_buflen);
 614                 RB_SC_SETCRC(crc);
 615
 616                 /*
 617                  * The soft_config partition is assumed to be entirely contained
 618                  * in a single eraseblock.
 619                  */
 620
 621                 ei.addr = 0;
 622                 ei.len = mtd->size;
 623                 ret = mtd_erase(mtd, &ei);
 624                 if (!ret)
 625                         ret = mtd_write(mtd, 0, mtd->size, &bytes_rw, sc_buf);
 626
 627                 /*
 628                  * Handling mtd_write() failure here is a tricky situation. The
 629                  * proposed approach is to let userspace deal with retrying,
 630                  * with the caveat that it must try to flush the buffer again as
 631                  * rereading the mtd contents could potentially read garbage.
 632                  * The rationale is: even if we keep a shadow buffer of the
 633                  * original content, there is no guarantee that we will ever be
 634                  * able to write it anyway.
 635                  * Regardless, it appears that RouterBOOT will ignore an invalid
 636                  * soft_config (including a completely wiped segment) and will
 637                  * write back factory defaults when it happens.
 638                  */
 639         }
 640         write_unlock(&sc_bufrwl);
 641
 642         if (ret)
 643                 goto mtdfail;
 644
 645         if (bytes_rw != sc_buflen) {
 646                 ret = -EIO;
 647                 goto mtdfail;
 648         }
 649
 650         return count;
 651
 652 mtdfail:
 653         RB_SC_CLRCRC(); // mark buffer content as dirty/invalid
 654         return ret;
 655 }
 656
 657 static struct kobj_attribute sc_kattrcommit = __ATTR(commit, RB_SC_RMODE|RB_SC_WMODE, sc_commit_show, sc_commit_store);
 658
 659 int __init rb_softconfig_init(struct kobject *rb_kobj)
 660 {
 661         struct mtd_info *mtd;
 662         size_t bytes_read, buflen;
 663         const u8 *buf;
 664         int i, ret;
 665         u32 magic;
 666
 667         sc_buf = NULL;
 668         sc_kobj = NULL;
 669
 670         // TODO allow override
 671         mtd = get_mtd_device_nm(RB_MTD_SOFT_CONFIG);
 672         if (IS_ERR(mtd))
 673                 return -ENODEV;
 674
 675         sc_buflen = mtd->size;
 676         sc_buf = kmalloc(sc_buflen, GFP_KERNEL);
 677         if (!sc_buf)
 678                 return -ENOMEM;
 679
 680         ret = mtd_read(mtd, 0, sc_buflen, &bytes_read, sc_buf);
 681
 682         if (ret)
 683                 goto fail;
 684
 685         if (bytes_read != sc_buflen) {
 686                 ret = -EIO;
 687                 goto fail;
 688         }
 689
 690         /* Check we have what we expect */
 691         magic = *(const u32 *)sc_buf;
 692         if (RB_MAGIC_SOFT != magic) {
 693                 ret = -EINVAL;
 694                 goto fail;
 695         }
 696
 697         /* Skip magic and 32bit CRC located immediately after */
 698         buf = sc_buf + (sizeof(magic) + sizeof(u32));
 699         buflen = sc_buflen - (sizeof(magic) + sizeof(u32));
 700
 701         /* Populate sysfs */
 702         ret = -ENOMEM;
 703         sc_kobj = kobject_create_and_add(RB_MTD_SOFT_CONFIG, rb_kobj);
 704         if (!sc_kobj)
 705                 goto fail;
 706
 707         rwlock_init(&sc_bufrwl);
 708
 709         /* Locate and publish all known tags */
 710         for (i = 0; i < ARRAY_SIZE(sc_attrs); i++) {
 711                 ret = routerboot_tag_find(buf, buflen, sc_attrs[i].tag_id,
 712                                           &sc_attrs[i].pld_ofs, &sc_attrs[i].pld_len);
 713                 if (ret) {
 714                         sc_attrs[i].pld_ofs = sc_attrs[i].pld_len = 0;
 715                         continue;
 716                 }
 717
 718                 /* Account for skipped magic and crc32 */
 719                 sc_attrs[i].pld_ofs += sizeof(magic) + sizeof(u32);
 720
 721                 ret = sysfs_create_file(sc_kobj, &sc_attrs[i].kattr.attr);
 722                 if (ret)
 723                         pr_warn(RB_SC_PR_PFX "Could not create %s sysfs entry (%d)\n",
 724                                sc_attrs[i].kattr.attr.name, ret);
 725         }
 726
 727         /* Finally add the 'commit' attribute */
 728         if (RB_SC_HAS_WRITE_SUPPORT) {
 729                 ret = sysfs_create_file(sc_kobj, &sc_kattrcommit.attr);
 730                 if (ret) {
 731                         pr_err(RB_SC_PR_PFX "Could not create %s sysfs entry (%d), aborting!\n",
 732                                sc_kattrcommit.attr.name, ret);
 733                         goto sysfsfail; // required attribute
 734                 }
 735         }
 736
 737         pr_info("MikroTik RouterBOARD software configuration sysfs driver v" RB_SOFTCONFIG_VER "\n");
 738
 739         return 0;
 740
 741 sysfsfail:
 742         kobject_put(sc_kobj);
 743         sc_kobj = NULL;
 744 fail:
 745         kfree(sc_buf);
 746         sc_buf = NULL;
 747         return ret;
 748 }
 749
 750 void __exit rb_softconfig_exit(void)
 751 {
 752         kobject_put(sc_kobj);
 753         kfree(sc_buf);
 754 }