SPI not working for STM32H7xx

int main(void)
{
  CPU_CACHE_Enable();
  HAL_Init();
  SystemClock_Config();
  SetupSPI();
  SetupSPI_GPIO();
  TMC5072_initMotorDrivers();
}

static void SetupSPI(void)
{
  __SPI5_CLK_ENABLE();
  SpiHandle.Instance               = SPI5;
  SpiHandle.Init.Mode              = SPI_MODE_MASTER;
  SpiHandle.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_256;
  SpiHandle.Init.Direction         = SPI_DIRECTION_2LINES;
  SpiHandle.Init.CLKPhase          = SPI_PHASE_2EDGE;
  SpiHandle.Init.CLKPolarity       = SPI_POLARITY_LOW;
  SpiHandle.Init.DataSize          = SPI_DATASIZE_8BIT;
  SpiHandle.Init.FirstBit          = SPI_FIRSTBIT_LSB;
  SpiHandle.Init.TIMode            = SPI_TIMODE_DISABLE;
  SpiHandle.Init.CRCCalculation    = SPI_CRCCALCULATION_DISABLE;
  SpiHandle.Init.NSS               = SPI_NSS_SOFT;
  SpiHandle.Init.NSSPMode          = SPI_NSS_PULSE_DISABLE;
  SpiHandle.Init.MasterKeepIOState = SPI_MASTER_KEEP_IO_STATE_ENABLE;
  __HAL_SPI_ENABLE(&SpiHandle);
  if (HAL_SPI_Init(&SpiHandle) != HAL_OK)
  {
   Error_Handler();
  }
}

/* Function to configure SPI Gpio's */
void SetupSPI_GPIO(void)
{
  /* PF7, PF8, PF9 configured as clock, MISO and MOSI respectively */
  __GPIOF_CLK_ENABLE();
  GPIO_InitTypeDef  GPIO_InitStruct;
  GPIO_InitStruct.Pin       = GPIO_PIN_7 | GPIO_PIN_8 | GPIO_PIN_9;
  GPIO_InitStruct.Mode      = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull      = GPIO_PULLUP;
  GPIO_InitStruct.Speed     = GPIO_SPEED_FREQ_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF5_SPI5;

  HAL_GPIO_Init(GPIOF, &GPIO_InitStruct);
  /* PF6 configured as NSS /*
  GPIO_InitStruct.Pin  = GPIO_PIN_6;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  HAL_GPIO_Init(GPIOF, &GPIO_InitStruct);
}


void TMC5072_initMotorDrivers()
{
  spi_writeRegister(0x00, 0xAAAAAAA);
}

void spi_writeRegister(uint8_t address, uint32_t data)
{
  uint8_t *buf[5];

  *buf[0] = data & 0xFF; // last 8bits
  *buf[1] = (data & 0xFF00) >> 8;
  *buf[2] = (data & 0xFF0000) >> 16;
  *buf[3] = (data & 0xFF000000) >> 24;
  *buf[4] = address | READ_ACCESS;

  /* hold chip select low when sending 40bit data */
  HAL_GPIO_WritePin(GPIOF, GPIO_PIN_6, GPIO_PIN_RESET);
  /* sending 40bit data */
  HAL_SPI_Transmit(&SpiHandle, (uint8_t *)buf, 40 , 0xFFFF);
  while(HAL_SPI_GetState(&SpiHandle) != HAL_SPI_STATE_READY)
  {
  }
  /* chip select high after data is sent */
  HAL_GPIO_WritePin(GPIOF, GPIO_PIN_6, GPIO_PIN_SET);

  HAL_Delay(2);
}

static void SystemClock_Config(void)
{
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  RCC_OscInitTypeDef RCC_OscInitStruct;
  HAL_StatusTypeDef ret = HAL_OK;

  /*!< Supply configuration update enable */
  MODIFY_REG(PWR->CR3, PWR_CR3_SCUEN, 0);

  /* The voltage scaling allows optimizing the power consumption when the device is
     clocked below the maximum system frequency, to update the voltage scaling value
     regarding system frequency refer to product datasheet.  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}

  /* Enable HSE Oscillator and activate PLL with HSE as source */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS;
  RCC_OscInitStruct.HSIState = RCC_HSI_OFF;
  RCC_OscInitStruct.CSIState = RCC_CSI_OFF;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;

  RCC_OscInitStruct.PLL.PLLM = 4;
  RCC_OscInitStruct.PLL.PLLN = 400;
  RCC_OscInitStruct.PLL.PLLP = 2;
  RCC_OscInitStruct.PLL.PLLR = 2;
  RCC_OscInitStruct.PLL.PLLQ = 4;

  RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
  RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_2;
  ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
  if(ret != HAL_OK)
  {
    Error_Handler();
  }

/* Select PLL as system clock source and configure  bus clocks dividers */
  RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_D1PCLK1 | RCC_CLOCKTYPE_PCLK1 | \ 
                                 RCC_CLOCKTYPE_PCLK2  | RCC_CLOCKTYPE_D3PCLK1);

  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
  RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;
  ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4);
  if(ret != HAL_OK)
  {
    Error_Handler();
  }
}