epmp_test_unlock.c

// Copyright lowRISC contributors (OpenTitan project).
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0
 
#include "sw/device/silicon_creator/lib/epmp_test_unlock.h"
 
#include <assert.h>
#include <stddef.h>
 
#include "sw/device/lib/arch/device.h"
#include "sw/device/lib/base/csr.h"
 
bool epmp_unlock_test_status(void) {
  // PMP entry dedicated to test status (DV).
  enum {
    kEntry = 6,
  };
 
  // Permissions to apply to test status address space.
  const epmp_perm_t kPerm = kEpmpPermLockedReadWrite;
 
  // Check that address space is word aligned.
  uintptr_t status_addr = device_test_status_address();
  if (status_addr % sizeof(uint32_t) != 0) {
    return false;
  }
 
  // Update the shadow register values.
  epmp_region_t region = {.start = status_addr,
                          .end = status_addr + sizeof(uint32_t)};
  epmp_state_configure_na4(kEntry, region, kPerm);
 
  // Update the hardware registers.
  static_assert(kEntry == 6, "PMP entry has changed, update CSR operations.");
  CSR_WRITE(CSR_REG_PMPADDR6, status_addr / sizeof(uint32_t));
  CSR_SET_BITS(CSR_REG_PMPCFG1, (kEpmpModeNa4 | kPerm)
                                    << ((kEntry % sizeof(uint32_t)) * 8));
 
  // Double check that the shadow registers match.
  if (!epmp_state_check()) {
    return false;
  }
 
  return true;
}