pinebuds/utils/retention_ram/retention_ram.c

/***************************************************************************
 *
 * Copyright 2015-2019 BES.
 * All rights reserved. All unpublished rights reserved.
 *
 * No part of this work may be used or reproduced in any form or by any
 * means, or stored in a database or retrieval system, without prior written
 * permission of BES.
 *
 * Use of this work is governed by a license granted by BES.
 * This work contains confidential and proprietary information of
 * BES. which is protected by copyright, trade secret,
 * trademark and other intellectual property rights.
 *
 ****************************************************************************/
#include "retention_ram.h"
#include "hal_timer.h"
#include "hal_trace.h"
#include "string.h"

#define OTA_RANDOM_BLE_BD_ADDR_MAGIC_CODE 0x51544F55
#define BLE_BD_ADDR_LEN 6
typedef struct {
  uint32_t magicCode; // 0x51544F55: "UOTA" means the OTA firmware should use
                      // the BD address in this structure, otherwise it will
                      // generate a random BD address
  uint8_t bleBdAddr[BLE_BD_ADDR_LEN];
} BLE_BD_ADDR_FOR_OTA_T;

// retained across the HW reset
BLE_BD_ADDR_FOR_OTA_T __attribute((section(".reboot_param"))) bleBdAddrForOta;
void fillBleBdAddrForOta(uint8_t *bdAddr) {
  bleBdAddrForOta.magicCode = OTA_RANDOM_BLE_BD_ADDR_MAGIC_CODE;
  memcpy(&(bleBdAddrForOta.bleBdAddr), bdAddr, BLE_BD_ADDR_LEN);
}

extern uint8_t ble_addr[BLE_BD_ADDR_LEN];
static unsigned int seed = 1;

static void set_rand_seed(unsigned int init) { seed = init; }

static int get_rand(void) {
  // Based on Knuth "The Art of Computer Programming"
  seed = seed * 1103515245 + 12345;
  return ((unsigned int)(seed / 65536) % (32767 + 1));
}

void otaConfigureBleBdAddr(void) {
  if (OTA_RANDOM_BLE_BD_ADDR_MAGIC_CODE == bleBdAddrForOta.magicCode) {
    // use the BD address saved in bleBdAddrForOta
    memcpy(&ble_addr, &(bleBdAddrForOta.bleBdAddr), BLE_BD_ADDR_LEN);

    // clear the magic code
    bleBdAddrForOta.magicCode = 0;
  } else {
    // generate the random BD static address
    int randomData;

    for (uint32_t index = 0; index < BLE_BD_ADDR_LEN / 2; index++) {
      set_rand_seed(hal_sys_timer_get());
      randomData = get_rand();
      TRACE(2, "randomData %d is 0x%x", index, randomData);
      memcpy(&(ble_addr[index * 2]), (uint8_t *)&randomData, 2);
    }

    // top two bits of the random static BD address are 1
    ble_addr[5] |= 0xC0;
  }
}