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               "0.03"
  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 upper levels (QCA955x), while F is presumably AR9344-only.
 127  */
 128 #define RB_CPU_FREQ_IDX_ATH79_A (0 << 3)
 129 #define RB_CPU_FREQ_IDX_ATH79_B (1 << 3)        // 0x8
 130 #define RB_CPU_FREQ_IDX_ATH79_C (2 << 3)        // 0x10 - factory freq for many devices
 131 #define RB_CPU_FREQ_IDX_ATH79_D (3 << 3)        // 0x18
 132 #define RB_CPU_FREQ_IDX_ATH79_E (4 << 3)        // 0x20
 133 #define RB_CPU_FREQ_IDX_ATH79_F (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 F
 137 #define RB_CPU_FREQ_IDX_ATH79_QCA953X_MAX       4       // stops at E
 138 #define RB_CPU_FREQ_IDX_ATH79_QCA9556_MAX       2       // stops at C
 139 #define RB_CPU_FREQ_IDX_ATH79_QCA9558_MAX       3       // stops at D
 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         // fallback to raw hex output if we can't handle the input
 172         if (tvselmts < 0)
 173                 return routerboot_tag_show_u32s(pld, pld_len, buf);
 174
 175         if (sizeof(data) != pld_len)
 176                 return -EINVAL;
 177
 178         read_lock(&sc_bufrwl);
 179         data = *(u32 *)pld;             // pld aliases sc_buf
 180         read_unlock(&sc_bufrwl);
 181
 182         for (i = 0; i < tvselmts; i++) {
 183                 fmt = (tvs[i].val == data) ? "[%s] " : "%s ";
 184                 out += sprintf(out, fmt, tvs[i].str);
 185         }
 186
 187         out += sprintf(out, "\n");
 188         return out - buf;
 189 }
 190
 191 static ssize_t sc_tag_store_u32tvs(const u8 *pld, u16 pld_len, const char *buf, size_t count,
 192                                    const struct sc_u32tvs tvs[], const int tvselmts)
 193 {
 194         int i;
 195
 196         if (tvselmts < 0)
 197                 return tvselmts;
 198
 199         if (sizeof(u32) != pld_len)
 200                 return -EINVAL;
 201
 202         for (i = 0; i < tvselmts; i++) {
 203                 if (sysfs_streq(buf, tvs[i].str)) {
 204                         write_lock(&sc_bufrwl);
 205                         *(u32 *)pld = tvs[i].val;       // pld aliases sc_buf
 206                         RB_SC_CLRCRC();
 207                         write_unlock(&sc_bufrwl);
 208                         return count;
 209                 }
 210         }
 211
 212         return -EINVAL;
 213 }
 214
 215 struct sc_boolts {
 216         const char *strfalse;
 217         const char *strtrue;
 218 };
 219
 220 static ssize_t sc_tag_show_boolts(const u8 *pld, u16 pld_len, char *buf,
 221                                   const struct sc_boolts *bts)
 222 {
 223         const char *fmt;
 224         char *out = buf;
 225         u32 data;       // cpu-endian
 226
 227         if (sizeof(data) != pld_len)
 228                 return -EINVAL;
 229
 230         read_lock(&sc_bufrwl);
 231         data = *(u32 *)pld;             // pld aliases sc_buf
 232         read_unlock(&sc_bufrwl);
 233
 234         fmt = (data) ? "%s [%s]\n" : "[%s] %s\n";
 235         out += sprintf(out, fmt, bts->strfalse, bts->strtrue);
 236
 237         return out - buf;
 238 }
 239
 240 static ssize_t sc_tag_store_boolts(const u8 *pld, u16 pld_len, const char *buf, size_t count,
 241                                    const struct sc_boolts *bts)
 242 {
 243         u32 data;       // cpu-endian
 244
 245         if (sizeof(data) != pld_len)
 246                 return -EINVAL;
 247
 248         if (sysfs_streq(buf, bts->strfalse))
 249                 data = 0;
 250         else if (sysfs_streq(buf, bts->strtrue))
 251                 data = 1;
 252         else
 253                 return -EINVAL;
 254
 255         write_lock(&sc_bufrwl);
 256         *(u32 *)pld = data;             // pld aliases sc_buf
 257         RB_SC_CLRCRC();
 258         write_unlock(&sc_bufrwl);
 259
 260         return count;
 261 }
 262 static struct sc_u32tvs const sc_uartspeeds[] = {
 263         RB_SC_TVS(RB_UART_SPEED_OFF,    "off"),
 264         RB_SC_TVS(RB_UART_SPEED_1200,   "1200"),
 265         RB_SC_TVS(RB_UART_SPEED_2400,   "2400"),
 266         RB_SC_TVS(RB_UART_SPEED_4800,   "4800"),
 267         RB_SC_TVS(RB_UART_SPEED_9600,   "9600"),
 268         RB_SC_TVS(RB_UART_SPEED_19200,  "19200"),
 269         RB_SC_TVS(RB_UART_SPEED_38400,  "38400"),
 270         RB_SC_TVS(RB_UART_SPEED_57600,  "57600"),
 271         RB_SC_TVS(RB_UART_SPEED_115200, "115200"),
 272 };
 273
 274 /*
 275  * While the defines are carried over from rbcfg, use strings that more clearly
 276  * show the actual setting purpose (especially since the NAND* settings apply
 277  * to both nand- and nor-based devices). "cfcard" was disabled in rbcfg: disable
 278  * it here too.
 279  */
 280 static struct sc_u32tvs const sc_bootdevices[] = {
 281         RB_SC_TVS(RB_BOOT_DEVICE_ETHER,         "eth"),
 282         RB_SC_TVS(RB_BOOT_DEVICE_NANDETH,       "flasheth"),
 283         //RB_SC_TVS(RB_BOOT_DEVICE_CFCARD,      "cfcard"),
 284         RB_SC_TVS(RB_BOOT_DEVICE_ETHONCE,       "ethonce"),
 285         RB_SC_TVS(RB_BOOT_DEVICE_NANDONLY,      "flash"),
 286         RB_SC_TVS(RB_BOOT_DEVICE_FLASHCFG,      "cfg"),
 287         RB_SC_TVS(RB_BOOT_DEVICE_FLSHONCE,      "cfgonce"),
 288 };
 289
 290 static struct sc_boolts const sc_bootkey = {
 291         .strfalse = "any",
 292         .strtrue = "del",
 293 };
 294
 295 static struct sc_boolts const sc_cpumode = {
 296         .strfalse = "powersave",
 297         .strtrue = "regular",
 298 };
 299
 300 static struct sc_boolts const sc_bootproto = {
 301         .strfalse = "bootp",
 302         .strtrue = "dhcp",
 303 };
 304
 305 static struct sc_boolts const sc_booter = {
 306         .strfalse = "regular",
 307         .strtrue = "backup",
 308 };
 309
 310 static struct sc_boolts const sc_silent_boot = {
 311         .strfalse = "off",
 312         .strtrue = "on",
 313 };
 314
 315 #define SC_TAG_SHOW_STORE_U32TVS_FUNCS(_name)           \
 316 static ssize_t sc_tag_show_##_name(const u8 *pld, u16 pld_len, char *buf)       \
 317 {                                                                               \
 318         return sc_tag_show_u32tvs(pld, pld_len, buf, sc_##_name, ARRAY_SIZE(sc_##_name));       \
 319 }                                                                               \
 320 static ssize_t sc_tag_store_##_name(const u8 *pld, u16 pld_len, const char *buf, size_t count)  \
 321 {                                                                               \
 322         return sc_tag_store_u32tvs(pld, pld_len, buf, count, sc_##_name, ARRAY_SIZE(sc_##_name));       \
 323 }
 324
 325 #define SC_TAG_SHOW_STORE_BOOLTS_FUNCS(_name)           \
 326 static ssize_t sc_tag_show_##_name(const u8 *pld, u16 pld_len, char *buf)       \
 327 {                                                                               \
 328         return sc_tag_show_boolts(pld, pld_len, buf, &sc_##_name);      \
 329 }                                                                               \
 330 static ssize_t sc_tag_store_##_name(const u8 *pld, u16 pld_len, const char *buf, size_t count)  \
 331 {                                                                               \
 332         return sc_tag_store_boolts(pld, pld_len, buf, count, &sc_##_name);      \
 333 }
 334
 335 SC_TAG_SHOW_STORE_U32TVS_FUNCS(uartspeeds)
 336 SC_TAG_SHOW_STORE_U32TVS_FUNCS(bootdevices)
 337 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(bootkey)
 338 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(cpumode)
 339 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(bootproto)
 340 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(booter)
 341 SC_TAG_SHOW_STORE_BOOLTS_FUNCS(silent_boot)
 342
 343 static ssize_t sc_tag_show_bootdelays(const u8 *pld, u16 pld_len, char *buf)
 344 {
 345         const char *fmt;
 346         char *out = buf;
 347         u32 data;       // cpu-endian
 348         int i;
 349
 350         if (sizeof(data) != pld_len)
 351                 return -EINVAL;
 352
 353         read_lock(&sc_bufrwl);
 354         data = *(u32 *)pld;             // pld aliases sc_buf
 355         read_unlock(&sc_bufrwl);
 356
 357         for (i = RB_BOOT_DELAY_MIN; i <= RB_BOOT_DELAY_MAX; i++) {
 358                 fmt = (i == data) ? "[%d] " : "%d ";
 359                 out += sprintf(out, fmt, i);
 360         }
 361
 362         out += sprintf(out, "\n");
 363         return out - buf;
 364 }
 365
 366 static ssize_t sc_tag_store_bootdelays(const u8 *pld, u16 pld_len, const char *buf, size_t count)
 367 {
 368         u32 data;       // cpu-endian
 369         int ret;
 370
 371         if (sizeof(data) != pld_len)
 372                 return -EINVAL;
 373
 374         ret = kstrtou32(buf, 10, &data);
 375         if (ret)
 376                 return ret;
 377
 378         if ((data < RB_BOOT_DELAY_MIN) || (RB_BOOT_DELAY_MAX < data))
 379                 return -EINVAL;
 380
 381         write_lock(&sc_bufrwl);
 382         *(u32 *)pld = data;             // pld aliases sc_buf
 383         RB_SC_CLRCRC();
 384         write_unlock(&sc_bufrwl);
 385
 386         return count;
 387 }
 388
 389 /* Support CPU frequency accessors only when the tag format has been asserted */
 390 #if defined(CONFIG_ATH79)
 391 /* Use the same letter-based nomenclature as RouterBOOT */
 392 static struct sc_u32tvs const sc_cpufreq_indexes_ath79[] = {
 393         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_A,      "a"),
 394         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_B,      "b"),
 395         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_C,      "c"),
 396         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_D,      "d"),
 397         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_E,      "e"),
 398         RB_SC_TVS(RB_CPU_FREQ_IDX_ATH79_F,      "f"),
 399 };
 400
 401 static int sc_tag_cpufreq_ath79_arraysize(void)
 402 {
 403         int idx_max;
 404
 405         if (soc_is_ar9344())
 406                 idx_max = RB_CPU_FREQ_IDX_ATH79_AR9334_MAX+1;
 407         else if (soc_is_qca953x())
 408                 idx_max = RB_CPU_FREQ_IDX_ATH79_QCA953X_MAX+1;
 409         else if (soc_is_qca9556())
 410                 idx_max = RB_CPU_FREQ_IDX_ATH79_QCA9556_MAX+1;
 411         else if (soc_is_qca9558())
 412                 idx_max = RB_CPU_FREQ_IDX_ATH79_QCA9558_MAX+1;
 413         else
 414                 idx_max = -EOPNOTSUPP;
 415
 416         return idx_max;
 417 }
 418
 419 static ssize_t sc_tag_show_cpufreq_indexes(const u8 *pld, u16 pld_len, char * buf)
 420 {
 421         return sc_tag_show_u32tvs(pld, pld_len, buf, sc_cpufreq_indexes_ath79, sc_tag_cpufreq_ath79_arraysize());
 422 }
 423
 424 static ssize_t sc_tag_store_cpufreq_indexes(const u8 *pld, u16 pld_len, const char *buf, size_t count)
 425 {
 426         return sc_tag_store_u32tvs(pld, pld_len, buf, count, sc_cpufreq_indexes_ath79, sc_tag_cpufreq_ath79_arraysize());
 427 }
 428 #else
 429  /* By default we only show the raw value to help with reverse-engineering */
 430  #define sc_tag_show_cpufreq_indexes    routerboot_tag_show_u32s
 431  #define sc_tag_store_cpufreq_indexes   NULL
 432 #endif
 433
 434 static ssize_t sc_attr_show(struct kobject *kobj, struct kobj_attribute *attr,
 435                             char *buf);
 436 static ssize_t sc_attr_store(struct kobject *kobj, struct kobj_attribute *attr,
 437                              const char *buf, size_t count);
 438
 439 /* Array of known tags to publish in sysfs */
 440 static struct sc_attr {
 441         const u16 tag_id;
 442         /* sysfs tag show attribute. Must lock sc_buf when dereferencing pld */
 443         ssize_t (* const tshow)(const u8 *pld, u16 pld_len, char *buf);
 444         /* sysfs tag store attribute. Must lock sc_buf when dereferencing pld */
 445         ssize_t (* const tstore)(const u8 *pld, u16 pld_len, const char *buf, size_t count);
 446         struct kobj_attribute kattr;
 447         u16 pld_ofs;
 448         u16 pld_len;
 449 } sc_attrs[] = {
 450         {
 451                 .tag_id = RB_SCID_UART_SPEED,
 452                 .tshow = sc_tag_show_uartspeeds,
 453                 .tstore = sc_tag_store_uartspeeds,
 454                 .kattr = __ATTR(uart_speed, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 455         }, {
 456                 .tag_id = RB_SCID_BOOT_DELAY,
 457                 .tshow = sc_tag_show_bootdelays,
 458                 .tstore = sc_tag_store_bootdelays,
 459                 .kattr = __ATTR(boot_delay, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 460         }, {
 461                 .tag_id = RB_SCID_BOOT_DEVICE,
 462                 .tshow = sc_tag_show_bootdevices,
 463                 .tstore = sc_tag_store_bootdevices,
 464                 .kattr = __ATTR(boot_device, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 465         }, {
 466                 .tag_id = RB_SCID_BOOT_KEY,
 467                 .tshow = sc_tag_show_bootkey,
 468                 .tstore = sc_tag_store_bootkey,
 469                 .kattr = __ATTR(boot_key, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 470         }, {
 471                 .tag_id = RB_SCID_CPU_MODE,
 472                 .tshow = sc_tag_show_cpumode,
 473                 .tstore = sc_tag_store_cpumode,
 474                 .kattr = __ATTR(cpu_mode, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 475         }, {
 476                 .tag_id = RB_SCID_BIOS_VERSION,
 477                 .tshow = routerboot_tag_show_string,
 478                 .tstore = NULL,
 479                 .kattr = __ATTR(bios_version, RB_SC_RMODE, sc_attr_show, NULL),
 480         }, {
 481                 .tag_id = RB_SCID_BOOT_PROTOCOL,
 482                 .tshow = sc_tag_show_bootproto,
 483                 .tstore = sc_tag_store_bootproto,
 484                 .kattr = __ATTR(boot_proto, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 485         }, {
 486                 .tag_id = RB_SCID_CPU_FREQ_IDX,
 487                 .tshow = sc_tag_show_cpufreq_indexes,
 488                 .tstore = sc_tag_store_cpufreq_indexes,
 489                 .kattr = __ATTR(cpufreq_index, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 490         }, {
 491                 .tag_id = RB_SCID_BOOTER,
 492                 .tshow = sc_tag_show_booter,
 493                 .tstore = sc_tag_store_booter,
 494                 .kattr = __ATTR(booter, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 495         }, {
 496                 .tag_id = RB_SCID_SILENT_BOOT,
 497                 .tshow = sc_tag_show_silent_boot,
 498                 .tstore = sc_tag_store_silent_boot,
 499                 .kattr = __ATTR(silent_boot, RB_SC_RMODE|RB_SC_WMODE, sc_attr_show, sc_attr_store),
 500         },
 501 };
 502
 503 static ssize_t sc_attr_show(struct kobject *kobj, struct kobj_attribute *attr,
 504                             char *buf)
 505 {
 506         const struct sc_attr *sc_attr;
 507         const u8 *pld;
 508         u16 pld_len;
 509
 510         sc_attr = container_of(attr, typeof(*sc_attr), kattr);
 511
 512         if (!sc_attr->pld_len)
 513                 return -ENOENT;
 514
 515         pld = sc_buf + sc_attr->pld_ofs;        // pld aliases sc_buf -> lock!
 516         pld_len = sc_attr->pld_len;
 517
 518         return sc_attr->tshow(pld, pld_len, buf);
 519 }
 520
 521 static ssize_t sc_attr_store(struct kobject *kobj, struct kobj_attribute *attr,
 522                              const char *buf, size_t count)
 523 {
 524         const struct sc_attr *sc_attr;
 525         const u8 *pld;
 526         u16 pld_len;
 527
 528         if (!RB_SC_HAS_WRITE_SUPPORT)
 529                 return -EOPNOTSUPP;
 530
 531         if (!capable(CAP_SYS_ADMIN))
 532                 return -EACCES;
 533
 534         sc_attr = container_of(attr, typeof(*sc_attr), kattr);
 535
 536         if (!sc_attr->tstore)
 537                 return -EOPNOTSUPP;
 538
 539         if (!sc_attr->pld_len)
 540                 return -ENOENT;
 541
 542         pld = sc_buf + sc_attr->pld_ofs;        // pld aliases sc_buf -> lock!
 543         pld_len = sc_attr->pld_len;
 544
 545         return sc_attr->tstore(pld, pld_len, buf, count);
 546 }
 547
 548 /*
 549  * Shows the current buffer status:
 550  * "clean": the buffer is in sync with the mtd data
 551  * "dirty": the buffer is out of sync with the mtd data
 552  */
 553 static ssize_t sc_commit_show(struct kobject *kobj, struct kobj_attribute *attr,
 554                               char *buf)
 555 {
 556         const char *str;
 557         char *out = buf;
 558         u32 crc;
 559
 560         read_lock(&sc_bufrwl);
 561         crc = RB_SC_GETCRC();
 562         read_unlock(&sc_bufrwl);
 563
 564         str = (crc) ? "clean" : "dirty";
 565         out += sprintf(out, "%s\n", str);
 566
 567         return out - buf;
 568 }
 569
 570 /*
 571  * Performs buffer flushing:
 572  * This routine expects an input compatible with kstrtobool().
 573  * - a "false" input discards the current changes and reads data back from mtd.
 574  * - a "true" input commits the current changes to mtd.
 575  * If there is no pending changes, this routine is a no-op.
 576  * Handling failures is left as an exercise to userspace.
 577  */
 578 static ssize_t sc_commit_store(struct kobject *kobj, struct kobj_attribute *attr,
 579                               const char *buf, size_t count)
 580 {
 581         struct mtd_info *mtd;
 582         struct erase_info ei;
 583         size_t bytes_rw, ret = count;
 584         bool flush;
 585         u32 crc;
 586
 587         if (!RB_SC_HAS_WRITE_SUPPORT)
 588                 return -EOPNOTSUPP;
 589
 590         read_lock(&sc_bufrwl);
 591         crc = RB_SC_GETCRC();
 592         read_unlock(&sc_bufrwl);
 593
 594         if (crc)
 595                 return count;   // NO-OP
 596
 597         ret = kstrtobool(buf, &flush);
 598         if (ret)
 599                 return ret;
 600
 601         mtd = get_mtd_device_nm(RB_MTD_SOFT_CONFIG);    // TODO allow override
 602         if (IS_ERR(mtd))
 603                 return -ENODEV;
 604
 605         write_lock(&sc_bufrwl);
 606         if (!flush)     // reread
 607                 ret = mtd_read(mtd, 0, mtd->size, &bytes_rw, sc_buf);
 608         else {  // crc32 + commit
 609                 /*
 610                  * CRC32 is computed on the entire buffer, excluding the CRC
 611                  * value itself. CRC is already null when we reach this point,
 612                  * so we can compute the CRC32 on the buffer as is.
 613                  * The expected CRC32 is Ethernet FCS style, meaning the seed is
 614                  * ~0 and the final result is also bitflipped.
 615                  */
 616
 617                 crc = ~crc32(~0, sc_buf, sc_buflen);
 618                 RB_SC_SETCRC(crc);
 619
 620                 /*
 621                  * The soft_config partition is assumed to be entirely contained
 622                  * in a single eraseblock.
 623                  */
 624
 625                 ei.addr = 0;
 626                 ei.len = mtd->size;
 627                 ret = mtd_erase(mtd, &ei);
 628                 if (!ret)
 629                         ret = mtd_write(mtd, 0, mtd->size, &bytes_rw, sc_buf);
 630
 631                 /*
 632                  * Handling mtd_write() failure here is a tricky situation. The
 633                  * proposed approach is to let userspace deal with retrying,
 634                  * with the caveat that it must try to flush the buffer again as
 635                  * rereading the mtd contents could potentially read garbage.
 636                  * The rationale is: even if we keep a shadow buffer of the
 637                  * original content, there is no guarantee that we will ever be
 638                  * able to write it anyway.
 639                  * Regardless, it appears that RouterBOOT will ignore an invalid
 640                  * soft_config (including a completely wiped segment) and will
 641                  * write back factory defaults when it happens.
 642                  */
 643         }
 644         write_unlock(&sc_bufrwl);
 645
 646         if (ret)
 647                 goto mtdfail;
 648
 649         if (bytes_rw != sc_buflen) {
 650                 ret = -EIO;
 651                 goto mtdfail;
 652         }
 653
 654         return count;
 655
 656 mtdfail:
 657         RB_SC_CLRCRC(); // mark buffer content as dirty/invalid
 658         return ret;
 659 }
 660
 661 static struct kobj_attribute sc_kattrcommit = __ATTR(commit, RB_SC_RMODE|RB_SC_WMODE, sc_commit_show, sc_commit_store);
 662
 663 int __init rb_softconfig_init(struct kobject *rb_kobj)
 664 {
 665         struct mtd_info *mtd;
 666         size_t bytes_read, buflen;
 667         const u8 *buf;
 668         int i, ret;
 669         u32 magic;
 670
 671         sc_buf = NULL;
 672         sc_kobj = NULL;
 673
 674         // TODO allow override
 675         mtd = get_mtd_device_nm(RB_MTD_SOFT_CONFIG);
 676         if (IS_ERR(mtd))
 677                 return -ENODEV;
 678
 679         sc_buflen = mtd->size;
 680         sc_buf = kmalloc(sc_buflen, GFP_KERNEL);
 681         if (!sc_buf)
 682                 return -ENOMEM;
 683
 684         ret = mtd_read(mtd, 0, sc_buflen, &bytes_read, sc_buf);
 685
 686         if (ret)
 687                 goto fail;
 688
 689         if (bytes_read != sc_buflen) {
 690                 ret = -EIO;
 691                 goto fail;
 692         }
 693
 694         /* Check we have what we expect */
 695         magic = *(const u32 *)sc_buf;
 696         if (RB_MAGIC_SOFT != magic) {
 697                 ret = -EINVAL;
 698                 goto fail;
 699         }
 700
 701         /* Skip magic and 32bit CRC located immediately after */
 702         buf = sc_buf + (sizeof(magic) + sizeof(u32));
 703         buflen = sc_buflen - (sizeof(magic) + sizeof(u32));
 704
 705         /* Populate sysfs */
 706         ret = -ENOMEM;
 707         sc_kobj = kobject_create_and_add(RB_MTD_SOFT_CONFIG, rb_kobj);
 708         if (!sc_kobj)
 709                 goto fail;
 710
 711         rwlock_init(&sc_bufrwl);
 712
 713         /* Locate and publish all known tags */
 714         for (i = 0; i < ARRAY_SIZE(sc_attrs); i++) {
 715                 ret = routerboot_tag_find(buf, buflen, sc_attrs[i].tag_id,
 716                                           &sc_attrs[i].pld_ofs, &sc_attrs[i].pld_len);
 717                 if (ret) {
 718                         sc_attrs[i].pld_ofs = sc_attrs[i].pld_len = 0;
 719                         continue;
 720                 }
 721
 722                 /* Account for skipped magic and crc32 */
 723                 sc_attrs[i].pld_ofs += sizeof(magic) + sizeof(u32);
 724
 725                 ret = sysfs_create_file(sc_kobj, &sc_attrs[i].kattr.attr);
 726                 if (ret)
 727                         pr_warn(RB_SC_PR_PFX "Could not create %s sysfs entry (%d)\n",
 728                                sc_attrs[i].kattr.attr.name, ret);
 729         }
 730
 731         /* Finally add the 'commit' attribute */
 732         if (RB_SC_HAS_WRITE_SUPPORT) {
 733                 ret = sysfs_create_file(sc_kobj, &sc_kattrcommit.attr);
 734                 if (ret) {
 735                         pr_err(RB_SC_PR_PFX "Could not create %s sysfs entry (%d), aborting!\n",
 736                                sc_kattrcommit.attr.name, ret);
 737                         goto sysfsfail; // required attribute
 738                 }
 739         }
 740
 741         pr_info("MikroTik RouterBOARD software configuration sysfs driver v" RB_SOFTCONFIG_VER "\n");
 742
 743         return 0;
 744
 745 sysfsfail:
 746         kobject_put(sc_kobj);
 747         sc_kobj = NULL;
 748 fail:
 749         kfree(sc_buf);
 750         sc_buf = NULL;
 751         return ret;
 752 }
 753
 754 void __exit rb_softconfig_exit(void)
 755 {
 756         kobject_put(sc_kobj);
 757         kfree(sc_buf);
 758 }