src/devices/nand/drivers/nandpart/nandpart-utils.cc

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "nandpart-utils.h"

#include <stdlib.h>
#include <string.h>
#include <zircon/assert.h>

#include <ddk/debug.h>
#include <fbl/algorithm.h>

// Checks that the partition map is valid, sorts it in partition order, and
// ensures blocks are on erase block boundaries.
zx_status_t SanitizePartitionMap(zbi_partition_map_t* pmap,
                                 const fuchsia_hardware_nand_Info& nand_info) {
  if (pmap->partition_count == 0) {
    zxlogf(ERROR, "nandpart: partition count is zero");
    return ZX_ERR_INTERNAL;
  }

  auto* const begin = &pmap->partitions[0];
  const auto* const end = &pmap->partitions[pmap->partition_count];

  // 1) Last block must be greater than first for each partition entry.
  for (auto* part = begin; part != end; part++) {
    if (part->first_block > part->last_block) {
      return ZX_ERR_INVALID_ARGS;
    }
  }

  // 2) Partitions should be in order.
  qsort(pmap->partitions, pmap->partition_count, sizeof(zbi_partition_t),
        [](const void* left, const void* right) {
          const auto* left_ = static_cast<const zbi_partition_t*>(left);
          const auto* right_ = static_cast<const zbi_partition_t*>(right);
          if (left_->first_block < right_->first_block) {
            return -1;
          }
          if (left_->first_block > right_->first_block) {
            return 1;
          }
          return 0;
        });

  // 3) Partitions should not be overlapping.
  for (auto *part = begin, *next = begin + 1; next != end; part++, next++) {
    if (part->last_block >= next->first_block) {
      zxlogf(ERROR, "nandpart: partition %s [%lu, %lu] overlaps partition %s [%lu, %lu]",
             part->name, part->first_block, part->last_block, next->name, next->first_block,
             next->last_block);
      return ZX_ERR_INTERNAL;
    }
  }

  // 4) All partitions must start at an erase block boundary.
  const size_t erase_block_size = nand_info.page_size * nand_info.pages_per_block;
  ZX_DEBUG_ASSERT(fbl::is_pow2(erase_block_size));
  const int block_shift = ffs(static_cast<int>(erase_block_size)) - 1;

  if (pmap->block_size != erase_block_size) {
    for (auto* part = begin; part != end; part++) {
      uint64_t first_byte_offset = part->first_block * pmap->block_size;
      uint64_t last_byte_offset = (part->last_block + 1) * pmap->block_size;

      if (fbl::round_down(first_byte_offset, erase_block_size) != first_byte_offset ||
          fbl::round_down(last_byte_offset, erase_block_size) != last_byte_offset) {
        zxlogf(ERROR, "nandpart: partition %s size is not a multiple of erase_block_size",
               part->name);
        return ZX_ERR_INTERNAL;
      }
      part->first_block = first_byte_offset >> block_shift;
      part->last_block = (last_byte_offset >> block_shift) - 1;
    }
  }
  // 5) Partitions should exist within NAND.
  if ((end - 1)->last_block >= nand_info.num_blocks) {
    return ZX_ERR_OUT_OF_RANGE;
  }
  return ZX_OK;
}