linux/drivers/firmware/turris-mox-rwtm.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Turris Mox rWTM firmware driver
   4 *
   5 * Copyright (C) 2019 Marek BehĂșn <kabel@kernel.org>
   6 */
   7
   8#include <linux/armada-37xx-rwtm-mailbox.h>
   9#include <linux/completion.h>
  10#include <linux/debugfs.h>
  11#include <linux/dma-mapping.h>
  12#include <linux/hw_random.h>
  13#include <linux/mailbox_client.h>
  14#include <linux/module.h>
  15#include <linux/mutex.h>
  16#include <linux/of.h>
  17#include <linux/platform_device.h>
  18#include <linux/slab.h>
  19
  20#define DRIVER_NAME             "turris-mox-rwtm"
  21
  22/*
  23 * The macros and constants below come from Turris Mox's rWTM firmware code.
  24 * This firmware is open source and it's sources can be found at
  25 * https://gitlab.labs.nic.cz/turris/mox-boot-builder/tree/master/wtmi.
  26 */
  27
  28#define MBOX_STS_SUCCESS        (0 << 30)
  29#define MBOX_STS_FAIL           (1 << 30)
  30#define MBOX_STS_BADCMD         (2 << 30)
  31#define MBOX_STS_ERROR(s)       ((s) & (3 << 30))
  32#define MBOX_STS_VALUE(s)       (((s) >> 10) & 0xfffff)
  33#define MBOX_STS_CMD(s)         ((s) & 0x3ff)
  34
  35enum mbox_cmd {
  36        MBOX_CMD_GET_RANDOM     = 1,
  37        MBOX_CMD_BOARD_INFO     = 2,
  38        MBOX_CMD_ECDSA_PUB_KEY  = 3,
  39        MBOX_CMD_HASH           = 4,
  40        MBOX_CMD_SIGN           = 5,
  41        MBOX_CMD_VERIFY         = 6,
  42
  43        MBOX_CMD_OTP_READ       = 7,
  44        MBOX_CMD_OTP_WRITE      = 8,
  45};
  46
  47struct mox_kobject;
  48
  49struct mox_rwtm {
  50        struct device *dev;
  51        struct mbox_client mbox_client;
  52        struct mbox_chan *mbox;
  53        struct mox_kobject *kobj;
  54        struct hwrng hwrng;
  55
  56        struct armada_37xx_rwtm_rx_msg reply;
  57
  58        void *buf;
  59        dma_addr_t buf_phys;
  60
  61        struct mutex busy;
  62        struct completion cmd_done;
  63
  64        /* board information */
  65        int has_board_info;
  66        u64 serial_number;
  67        int board_version, ram_size;
  68        u8 mac_address1[6], mac_address2[6];
  69
  70        /* public key burned in eFuse */
  71        int has_pubkey;
  72        u8 pubkey[135];
  73
  74#ifdef CONFIG_DEBUG_FS
  75        /*
  76         * Signature process. This is currently done via debugfs, because it
  77         * does not conform to the sysfs standard "one file per attribute".
  78         * It should be rewritten via crypto API once akcipher API is available
  79         * from userspace.
  80         */
  81        struct dentry *debugfs_root;
  82        u32 last_sig[34];
  83        int last_sig_done;
  84#endif
  85};
  86
  87struct mox_kobject {
  88        struct kobject kobj;
  89        struct mox_rwtm *rwtm;
  90};
  91
  92static inline struct kobject *rwtm_to_kobj(struct mox_rwtm *rwtm)
  93{
  94        return &rwtm->kobj->kobj;
  95}
  96
  97static inline struct mox_rwtm *to_rwtm(struct kobject *kobj)
  98{
  99        return container_of(kobj, struct mox_kobject, kobj)->rwtm;
 100}
 101
 102static void mox_kobj_release(struct kobject *kobj)
 103{
 104        kfree(to_rwtm(kobj)->kobj);
 105}
 106
 107static struct kobj_type mox_kobj_ktype = {
 108        .release        = mox_kobj_release,
 109        .sysfs_ops      = &kobj_sysfs_ops,
 110};
 111
 112static int mox_kobj_create(struct mox_rwtm *rwtm)
 113{
 114        rwtm->kobj = kzalloc(sizeof(*rwtm->kobj), GFP_KERNEL);
 115        if (!rwtm->kobj)
 116                return -ENOMEM;
 117
 118        kobject_init(rwtm_to_kobj(rwtm), &mox_kobj_ktype);
 119        if (kobject_add(rwtm_to_kobj(rwtm), firmware_kobj, "turris-mox-rwtm")) {
 120                kobject_put(rwtm_to_kobj(rwtm));
 121                return -ENXIO;
 122        }
 123
 124        rwtm->kobj->rwtm = rwtm;
 125
 126        return 0;
 127}
 128
 129#define MOX_ATTR_RO(name, format, cat)                          \
 130static ssize_t                                                  \
 131name##_show(struct kobject *kobj, struct kobj_attribute *a,     \
 132            char *buf)                                          \
 133{                                                               \
 134        struct mox_rwtm *rwtm = to_rwtm(kobj);  \
 135        if (!rwtm->has_##cat)                                   \
 136                return -ENODATA;                                \
 137        return sprintf(buf, format, rwtm->name);                \
 138}                                                               \
 139static struct kobj_attribute mox_attr_##name = __ATTR_RO(name)
 140
 141MOX_ATTR_RO(serial_number, "%016llX\n", board_info);
 142MOX_ATTR_RO(board_version, "%i\n", board_info);
 143MOX_ATTR_RO(ram_size, "%i\n", board_info);
 144MOX_ATTR_RO(mac_address1, "%pM\n", board_info);
 145MOX_ATTR_RO(mac_address2, "%pM\n", board_info);
 146MOX_ATTR_RO(pubkey, "%s\n", pubkey);
 147
 148static int mox_get_status(enum mbox_cmd cmd, u32 retval)
 149{
 150        if (MBOX_STS_CMD(retval) != cmd)
 151                return -EIO;
 152        else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
 153                return -(int)MBOX_STS_VALUE(retval);
 154        else if (MBOX_STS_ERROR(retval) == MBOX_STS_BADCMD)
 155                return -ENOSYS;
 156        else if (MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
 157                return -EIO;
 158        else
 159                return MBOX_STS_VALUE(retval);
 160}
 161
 162static const struct attribute *mox_rwtm_attrs[] = {
 163        &mox_attr_serial_number.attr,
 164        &mox_attr_board_version.attr,
 165        &mox_attr_ram_size.attr,
 166        &mox_attr_mac_address1.attr,
 167        &mox_attr_mac_address2.attr,
 168        &mox_attr_pubkey.attr,
 169        NULL
 170};
 171
 172static void mox_rwtm_rx_callback(struct mbox_client *cl, void *data)
 173{
 174        struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
 175        struct armada_37xx_rwtm_rx_msg *msg = data;
 176
 177        rwtm->reply = *msg;
 178        complete(&rwtm->cmd_done);
 179}
 180
 181static void reply_to_mac_addr(u8 *mac, u32 t1, u32 t2)
 182{
 183        mac[0] = t1 >> 8;
 184        mac[1] = t1;
 185        mac[2] = t2 >> 24;
 186        mac[3] = t2 >> 16;
 187        mac[4] = t2 >> 8;
 188        mac[5] = t2;
 189}
 190
 191static int mox_get_board_info(struct mox_rwtm *rwtm)
 192{
 193        struct armada_37xx_rwtm_tx_msg msg;
 194        struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
 195        int ret;
 196
 197        msg.command = MBOX_CMD_BOARD_INFO;
 198        ret = mbox_send_message(rwtm->mbox, &msg);
 199        if (ret < 0)
 200                return ret;
 201
 202        ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
 203        if (ret < 0)
 204                return ret;
 205
 206        ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
 207        if (ret == -ENODATA) {
 208                dev_warn(rwtm->dev,
 209                         "Board does not have manufacturing information burned!\n");
 210        } else if (ret == -ENOSYS) {
 211                dev_notice(rwtm->dev,
 212                           "Firmware does not support the BOARD_INFO command\n");
 213        } else if (ret < 0) {
 214                return ret;
 215        } else {
 216                rwtm->serial_number = reply->status[1];
 217                rwtm->serial_number <<= 32;
 218                rwtm->serial_number |= reply->status[0];
 219                rwtm->board_version = reply->status[2];
 220                rwtm->ram_size = reply->status[3];
 221                reply_to_mac_addr(rwtm->mac_address1, reply->status[4],
 222                                  reply->status[5]);
 223                reply_to_mac_addr(rwtm->mac_address2, reply->status[6],
 224                                  reply->status[7]);
 225                rwtm->has_board_info = 1;
 226
 227                pr_info("Turris Mox serial number %016llX\n",
 228                        rwtm->serial_number);
 229                pr_info("           board version %i\n", rwtm->board_version);
 230                pr_info("           burned RAM size %i MiB\n", rwtm->ram_size);
 231        }
 232
 233        msg.command = MBOX_CMD_ECDSA_PUB_KEY;
 234        ret = mbox_send_message(rwtm->mbox, &msg);
 235        if (ret < 0)
 236                return ret;
 237
 238        ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
 239        if (ret < 0)
 240                return ret;
 241
 242        ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
 243        if (ret == -ENODATA) {
 244                dev_warn(rwtm->dev, "Board has no public key burned!\n");
 245        } else if (ret == -ENOSYS) {
 246                dev_notice(rwtm->dev,
 247                           "Firmware does not support the ECDSA_PUB_KEY command\n");
 248        } else if (ret < 0) {
 249                return ret;
 250        } else {
 251                u32 *s = reply->status;
 252
 253                rwtm->has_pubkey = 1;
 254                sprintf(rwtm->pubkey,
 255                        "%06x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
 256                        ret, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7],
 257                        s[8], s[9], s[10], s[11], s[12], s[13], s[14], s[15]);
 258        }
 259
 260        return 0;
 261}
 262
 263static int check_get_random_support(struct mox_rwtm *rwtm)
 264{
 265        struct armada_37xx_rwtm_tx_msg msg;
 266        int ret;
 267
 268        msg.command = MBOX_CMD_GET_RANDOM;
 269        msg.args[0] = 1;
 270        msg.args[1] = rwtm->buf_phys;
 271        msg.args[2] = 4;
 272
 273        ret = mbox_send_message(rwtm->mbox, &msg);
 274        if (ret < 0)
 275                return ret;
 276
 277        ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
 278        if (ret < 0)
 279                return ret;
 280
 281        return mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
 282}
 283
 284static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 285{
 286        struct mox_rwtm *rwtm = (struct mox_rwtm *) rng->priv;
 287        struct armada_37xx_rwtm_tx_msg msg;
 288        int ret;
 289
 290        if (max > 4096)
 291                max = 4096;
 292
 293        msg.command = MBOX_CMD_GET_RANDOM;
 294        msg.args[0] = 1;
 295        msg.args[1] = rwtm->buf_phys;
 296        msg.args[2] = (max + 3) & ~3;
 297
 298        if (!wait) {
 299                if (!mutex_trylock(&rwtm->busy))
 300                        return -EBUSY;
 301        } else {
 302                mutex_lock(&rwtm->busy);
 303        }
 304
 305        ret = mbox_send_message(rwtm->mbox, &msg);
 306        if (ret < 0)
 307                goto unlock_mutex;
 308
 309        ret = wait_for_completion_interruptible(&rwtm->cmd_done);
 310        if (ret < 0)
 311                goto unlock_mutex;
 312
 313        ret = mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
 314        if (ret < 0)
 315                goto unlock_mutex;
 316
 317        memcpy(data, rwtm->buf, max);
 318        ret = max;
 319
 320unlock_mutex:
 321        mutex_unlock(&rwtm->busy);
 322        return ret;
 323}
 324
 325#ifdef CONFIG_DEBUG_FS
 326static int rwtm_debug_open(struct inode *inode, struct file *file)
 327{
 328        file->private_data = inode->i_private;
 329
 330        return nonseekable_open(inode, file);
 331}
 332
 333static ssize_t do_sign_read(struct file *file, char __user *buf, size_t len,
 334                            loff_t *ppos)
 335{
 336        struct mox_rwtm *rwtm = file->private_data;
 337        ssize_t ret;
 338
 339        /* only allow one read, of 136 bytes, from position 0 */
 340        if (*ppos != 0)
 341                return 0;
 342
 343        if (len < 136)
 344                return -EINVAL;
 345
 346        if (!rwtm->last_sig_done)
 347                return -ENODATA;
 348
 349        /* 2 arrays of 17 32-bit words are 136 bytes */
 350        ret = simple_read_from_buffer(buf, len, ppos, rwtm->last_sig, 136);
 351        rwtm->last_sig_done = 0;
 352
 353        return ret;
 354}
 355
 356static ssize_t do_sign_write(struct file *file, const char __user *buf,
 357                             size_t len, loff_t *ppos)
 358{
 359        struct mox_rwtm *rwtm = file->private_data;
 360        struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
 361        struct armada_37xx_rwtm_tx_msg msg;
 362        loff_t dummy = 0;
 363        ssize_t ret;
 364
 365        /* the input is a SHA-512 hash, so exactly 64 bytes have to be read */
 366        if (len != 64)
 367                return -EINVAL;
 368
 369        /* if last result is not zero user has not read that information yet */
 370        if (rwtm->last_sig_done)
 371                return -EBUSY;
 372
 373        if (!mutex_trylock(&rwtm->busy))
 374                return -EBUSY;
 375
 376        /*
 377         * Here we have to send:
 378         *   1. Address of the input to sign.
 379         *      The input is an array of 17 32-bit words, the first (most
 380         *      significat) is 0, the rest 16 words are copied from the SHA-512
 381         *      hash given by the user and converted from BE to LE.
 382         *   2. Address of the buffer where ECDSA signature value R shall be
 383         *      stored by the rWTM firmware.
 384         *   3. Address of the buffer where ECDSA signature value S shall be
 385         *      stored by the rWTM firmware.
 386         */
 387        memset(rwtm->buf, 0, 4);
 388        ret = simple_write_to_buffer(rwtm->buf + 4, 64, &dummy, buf, len);
 389        if (ret < 0)
 390                goto unlock_mutex;
 391        be32_to_cpu_array(rwtm->buf, rwtm->buf, 17);
 392
 393        msg.command = MBOX_CMD_SIGN;
 394        msg.args[0] = 1;
 395        msg.args[1] = rwtm->buf_phys;
 396        msg.args[2] = rwtm->buf_phys + 68;
 397        msg.args[3] = rwtm->buf_phys + 2 * 68;
 398        ret = mbox_send_message(rwtm->mbox, &msg);
 399        if (ret < 0)
 400                goto unlock_mutex;
 401
 402        ret = wait_for_completion_interruptible(&rwtm->cmd_done);
 403        if (ret < 0)
 404                goto unlock_mutex;
 405
 406        ret = MBOX_STS_VALUE(reply->retval);
 407        if (MBOX_STS_ERROR(reply->retval) != MBOX_STS_SUCCESS)
 408                goto unlock_mutex;
 409
 410        /*
 411         * Here we read the R and S values of the ECDSA signature
 412         * computed by the rWTM firmware and convert their words from
 413         * LE to BE.
 414         */
 415        memcpy(rwtm->last_sig, rwtm->buf + 68, 136);
 416        cpu_to_be32_array(rwtm->last_sig, rwtm->last_sig, 34);
 417        rwtm->last_sig_done = 1;
 418
 419        mutex_unlock(&rwtm->busy);
 420        return len;
 421unlock_mutex:
 422        mutex_unlock(&rwtm->busy);
 423        return ret;
 424}
 425
 426static const struct file_operations do_sign_fops = {
 427        .owner  = THIS_MODULE,
 428        .open   = rwtm_debug_open,
 429        .read   = do_sign_read,
 430        .write  = do_sign_write,
 431        .llseek = no_llseek,
 432};
 433
 434static int rwtm_register_debugfs(struct mox_rwtm *rwtm)
 435{
 436        struct dentry *root, *entry;
 437
 438        root = debugfs_create_dir("turris-mox-rwtm", NULL);
 439
 440        if (IS_ERR(root))
 441                return PTR_ERR(root);
 442
 443        entry = debugfs_create_file_unsafe("do_sign", 0600, root, rwtm,
 444                                           &do_sign_fops);
 445        if (IS_ERR(entry))
 446                goto err_remove;
 447
 448        rwtm->debugfs_root = root;
 449
 450        return 0;
 451err_remove:
 452        debugfs_remove_recursive(root);
 453        return PTR_ERR(entry);
 454}
 455
 456static void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
 457{
 458        debugfs_remove_recursive(rwtm->debugfs_root);
 459}
 460#else
 461static inline int rwtm_register_debugfs(struct mox_rwtm *rwtm)
 462{
 463        return 0;
 464}
 465
 466static inline void rwtm_unregister_debugfs(struct mox_rwtm *rwtm)
 467{
 468}
 469#endif
 470
 471static int turris_mox_rwtm_probe(struct platform_device *pdev)
 472{
 473        struct mox_rwtm *rwtm;
 474        struct device *dev = &pdev->dev;
 475        int ret;
 476
 477        rwtm = devm_kzalloc(dev, sizeof(*rwtm), GFP_KERNEL);
 478        if (!rwtm)
 479                return -ENOMEM;
 480
 481        rwtm->dev = dev;
 482        rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
 483                                        GFP_KERNEL);
 484        if (!rwtm->buf)
 485                return -ENOMEM;
 486
 487        ret = mox_kobj_create(rwtm);
 488        if (ret < 0) {
 489                dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
 490                return ret;
 491        }
 492
 493        ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
 494        if (ret < 0) {
 495                dev_err(dev, "Cannot create sysfs files!\n");
 496                goto put_kobj;
 497        }
 498
 499        platform_set_drvdata(pdev, rwtm);
 500
 501        mutex_init(&rwtm->busy);
 502
 503        rwtm->mbox_client.dev = dev;
 504        rwtm->mbox_client.rx_callback = mox_rwtm_rx_callback;
 505
 506        rwtm->mbox = mbox_request_channel(&rwtm->mbox_client, 0);
 507        if (IS_ERR(rwtm->mbox)) {
 508                ret = PTR_ERR(rwtm->mbox);
 509                if (ret != -EPROBE_DEFER)
 510                        dev_err(dev, "Cannot request mailbox channel: %i\n",
 511                                ret);
 512                goto remove_files;
 513        }
 514
 515        init_completion(&rwtm->cmd_done);
 516
 517        ret = mox_get_board_info(rwtm);
 518        if (ret < 0)
 519                dev_warn(dev, "Cannot read board information: %i\n", ret);
 520
 521        ret = check_get_random_support(rwtm);
 522        if (ret < 0) {
 523                dev_notice(dev,
 524                           "Firmware does not support the GET_RANDOM command\n");
 525                goto free_channel;
 526        }
 527
 528        rwtm->hwrng.name = DRIVER_NAME "_hwrng";
 529        rwtm->hwrng.read = mox_hwrng_read;
 530        rwtm->hwrng.priv = (unsigned long) rwtm;
 531        rwtm->hwrng.quality = 1024;
 532
 533        ret = devm_hwrng_register(dev, &rwtm->hwrng);
 534        if (ret < 0) {
 535                dev_err(dev, "Cannot register HWRNG: %i\n", ret);
 536                goto free_channel;
 537        }
 538
 539        ret = rwtm_register_debugfs(rwtm);
 540        if (ret < 0) {
 541                dev_err(dev, "Failed creating debugfs entries: %i\n", ret);
 542                goto free_channel;
 543        }
 544
 545        dev_info(dev, "HWRNG successfully registered\n");
 546
 547        return 0;
 548
 549free_channel:
 550        mbox_free_channel(rwtm->mbox);
 551remove_files:
 552        sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
 553put_kobj:
 554        kobject_put(rwtm_to_kobj(rwtm));
 555        return ret;
 556}
 557
 558static int turris_mox_rwtm_remove(struct platform_device *pdev)
 559{
 560        struct mox_rwtm *rwtm = platform_get_drvdata(pdev);
 561
 562        rwtm_unregister_debugfs(rwtm);
 563        sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
 564        kobject_put(rwtm_to_kobj(rwtm));
 565        mbox_free_channel(rwtm->mbox);
 566
 567        return 0;
 568}
 569
 570static const struct of_device_id turris_mox_rwtm_match[] = {
 571        { .compatible = "cznic,turris-mox-rwtm", },
 572        { .compatible = "marvell,armada-3700-rwtm-firmware", },
 573        { },
 574};
 575
 576MODULE_DEVICE_TABLE(of, turris_mox_rwtm_match);
 577
 578static struct platform_driver turris_mox_rwtm_driver = {
 579        .probe  = turris_mox_rwtm_probe,
 580        .remove = turris_mox_rwtm_remove,
 581        .driver = {
 582                .name           = DRIVER_NAME,
 583                .of_match_table = turris_mox_rwtm_match,
 584        },
 585};
 586module_platform_driver(turris_mox_rwtm_driver);
 587
 588MODULE_LICENSE("GPL v2");
 589MODULE_DESCRIPTION("Turris Mox rWTM firmware driver");
 590MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
 591