sw/device/lib/testing/entropy_testutils.c

// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

#include "sw/device/lib/base/mmio.h"
#include "sw/device/lib/dif/dif_csrng.h"
#include "sw/device/lib/dif/dif_edn.h"
#include "sw/device/lib/dif/dif_entropy_src.h"
#include "sw/device/lib/testing/test_framework/check.h"

#include "edn_regs.h"          // Generated
#include "entropy_src_regs.h"  // Generated
#include "hw/top_earlgrey/sw/autogen/top_earlgrey.h"

void entropy_testutils_auto_mode_init(void) {
  const dif_csrng_t csrng = {
      .base_addr = mmio_region_from_addr(TOP_EARLGREY_CSRNG_BASE_ADDR)};
  const dif_edn_t edn0 = {
      .base_addr = mmio_region_from_addr(TOP_EARLGREY_EDN0_BASE_ADDR)};
  const dif_edn_t edn1 = {
      .base_addr = mmio_region_from_addr(TOP_EARLGREY_EDN1_BASE_ADDR)};

  // Disable CSRNG.  This is required to abort the generate command of boot
  // mode, which is likely still running.
  CHECK_DIF_OK(dif_csrng_stop(&csrng));

  // Stop both EDNs.
  CHECK_DIF_OK(dif_edn_stop(&edn0));
  CHECK_DIF_OK(dif_edn_stop(&edn1));

  // Re-enable the CSRNG.
  CHECK_DIF_OK(dif_csrng_configure(&csrng));

  // Re-enable EDN0 in auto mode.
  const dif_edn_auto_params_t edn0_params = {
      // EDN0 provides lower-quality entropy.  Let one generate command return 8
      // blocks, and reseed every 32 generates.
      .reseed_material =
          {
              .len = 1,
              .data = {0x00000002},  // Reseed from entropy source only.
          },
      .generate_material =
          {
              .len = 1, .data = {0x00008003},  // One generate returns 8 blocks.
          },
      .reseed_interval = 32,  // Reseed every 32 generates.
  };
  CHECK_DIF_OK(dif_edn_set_auto_mode(&edn0, edn0_params));

  // Re-enable EDN1 in auto mode.
  const dif_edn_auto_params_t edn1_params = {
      // EDN1 provides highest-quality entropy.  Let one generate command
      // return 1 block, and reseed after every generate.
      .reseed_material =
          {
              .len = 1,
              .data = {0x00000002},  // Reseed from entropy source only.
          },
      .generate_material =
          {
              .len = 1, .data = {0x00001003},  // One generate returns 1 block.
          },
      .reseed_interval = 1,  // Reseed after every generate.
  };
  CHECK_DIF_OK(dif_edn_set_auto_mode(&edn1, edn1_params));
}

static void setup_entropy_src(void) {
  dif_entropy_src_t entropy_src;
  CHECK_DIF_OK(dif_entropy_src_init(
      mmio_region_from_addr(TOP_EARLGREY_ENTROPY_SRC_BASE_ADDR), &entropy_src));

  // Disable entropy for test purpose, as it has been turned on by ROM
  CHECK_DIF_OK(dif_entropy_src_set_enabled(&entropy_src, kDifToggleDisabled));

  const dif_entropy_src_config_t config = {
      .fips_enable = true,
      .route_to_firmware = false,
      .single_bit_mode = kDifEntropySrcSingleBitModeDisabled,
  };
  CHECK_DIF_OK(
      dif_entropy_src_configure(&entropy_src, config, kDifToggleEnabled));
}

static void setup_csrng(void) {
  dif_csrng_t csrng;
  CHECK_DIF_OK(dif_csrng_init(
      mmio_region_from_addr(TOP_EARLGREY_CSRNG_BASE_ADDR), &csrng));

  CHECK_DIF_OK(dif_csrng_configure(&csrng));
}

static void setup_edn() {
  // Temporary solution to configure/enable the EDN and CSRNG to allow OTBN to
  // run before a DIF is available,
  // https://github.com/lowRISC/opentitan/issues/6082
  // disable edn.
  uint32_t reg = 0;
  reg =
      bitfield_field32_write(0, EDN_CTRL_EDN_ENABLE_FIELD, kMultiBitBool4False);
  reg = bitfield_field32_write(reg, EDN_CTRL_BOOT_REQ_MODE_FIELD,
                               kMultiBitBool4False);
  reg = bitfield_field32_write(reg, EDN_CTRL_AUTO_REQ_MODE_FIELD,
                               kMultiBitBool4False);
  reg = bitfield_field32_write(reg, EDN_CTRL_CMD_FIFO_RST_FIELD,
                               kMultiBitBool4False);
  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN0_BASE_ADDR),
                      EDN_CTRL_REG_OFFSET, reg);
  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN1_BASE_ADDR),
                      EDN_CTRL_REG_OFFSET, reg);

  reg =
      bitfield_field32_write(0, EDN_CTRL_EDN_ENABLE_FIELD, kMultiBitBool4True);
  reg = bitfield_field32_write(reg, EDN_CTRL_BOOT_REQ_MODE_FIELD,
                               kMultiBitBool4True);
  reg = bitfield_field32_write(reg, EDN_CTRL_AUTO_REQ_MODE_FIELD,
                               kMultiBitBool4False);
  reg = bitfield_field32_write(reg, EDN_CTRL_CMD_FIFO_RST_FIELD,
                               kMultiBitBool4False);
  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN0_BASE_ADDR),
                      EDN_CTRL_REG_OFFSET, reg);
  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN1_BASE_ADDR),
                      EDN_CTRL_REG_OFFSET, reg);
}

void entropy_testutils_boot_mode_init(void) {
  setup_entropy_src();
  setup_csrng();
  setup_edn();
}

void entropy_testutils_wait_for_state(const dif_entropy_src_t *entropy_src,
                                      dif_entropy_src_main_fsm_t state) {
  dif_entropy_src_main_fsm_t cur_state;

  do {
    CHECK_DIF_OK(dif_entropy_src_get_main_fsm_state(entropy_src, &cur_state));
  } while (cur_state != state);
}