path: root/os/hal/platforms/STM32/sdc_lld.c

/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    STM32/sdc_lld.c
 * @brief   STM32 SDC subsystem low level driver source.
 *
 * @addtogroup SDC
 * @{
 */

/*
 TODO: Try preerase blocks before writing (ACMD23).
 */

#include <string.h>

#include "ch.h"
#include "hal.h"

#if HAL_USE_SDC || defined(__DOXYGEN__)

/*===========================================================================*/
/* Driver local definitions.                                                 */
/*===========================================================================*/

#define DMA_CHANNEL                                                         \
  STM32_DMA_GETCHANNEL(STM32_SDC_SDIO_DMA_STREAM,                           \
                       STM32_SDC_SDIO_DMA_CHN)

/*===========================================================================*/
/* Driver exported variables.                                                */
/*===========================================================================*/

/** @brief SDCD1 driver identifier.*/
SDCDriver SDCD1;

/*===========================================================================*/
/* Driver local variables.                                                   */
/*===========================================================================*/

#if STM32_SDC_SDIO_UNALIGNED_SUPPORT
/**
 * @brief   Buffer for temporary storage during unaligned transfers.
 */
static union {
  uint32_t  alignment;
  uint8_t   buf[MMCSD_BLOCK_SIZE];
} u;
#endif /* STM32_SDC_SDIO_UNALIGNED_SUPPORT */

/*===========================================================================*/
/* Driver local functions.                                                   */
/*===========================================================================*/

/**
 * @brief   Prepares card to handle read transaction.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] startblk  first block to read
 * @param[in] n         number of blocks to read
 * @param[in] resp      pointer to the response buffer
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
static bool_t sdc_lld_prepare_read(SDCDriver *sdcp, uint32_t startblk,
                                   uint32_t n, uint32_t *resp) {

  /* Driver handles data in 512 bytes blocks (just like HC cards). But if we
     have not HC card than we must convert address from blocks to bytes.*/
  if (!(sdcp->cardmode & SDC_MODE_HIGH_CAPACITY))
    startblk *= MMCSD_BLOCK_SIZE;

  if (n > 1) {
    /* Send read multiple blocks command to card.*/
    if (sdc_lld_send_cmd_short_crc(sdcp, MMCSD_CMD_READ_MULTIPLE_BLOCK,
                                   startblk, resp) || MMCSD_R1_ERROR(resp[0]))
      return CH_FAILED;
  }
  else{
    /* Send read single block command.*/
    if (sdc_lld_send_cmd_short_crc(sdcp, MMCSD_CMD_READ_SINGLE_BLOCK,
                                   startblk, resp) || MMCSD_R1_ERROR(resp[0]))
      return CH_FAILED;
  }

  return CH_SUCCESS;
}

/**
 * @brief   Prepares card to handle write transaction.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] startblk  first block to read
 * @param[in] n         number of blocks to write
 * @param[in] resp      pointer to the response buffer
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
static bool_t sdc_lld_prepare_write(SDCDriver *sdcp, uint32_t startblk,
                                    uint32_t n, uint32_t *resp) {

  /* Driver handles data in 512 bytes blocks (just like HC cards). But if we
     have not HC card than we must convert address from blocks to bytes.*/
  if (!(sdcp->cardmode & SDC_MODE_HIGH_CAPACITY))
    startblk *= MMCSD_BLOCK_SIZE;

  if (n > 1) {
    /* Write multiple blocks command.*/
    if (sdc_lld_send_cmd_short_crc(sdcp, MMCSD_CMD_WRITE_MULTIPLE_BLOCK,
                                   startblk, resp) || MMCSD_R1_ERROR(resp[0]))
      return CH_FAILED;
  }
  else{
    /* Write single block command.*/
    if (sdc_lld_send_cmd_short_crc(sdcp, MMCSD_CMD_WRITE_BLOCK,
                                   startblk, resp) || MMCSD_R1_ERROR(resp[0]))
      return CH_FAILED;
  }

  return CH_SUCCESS;
}

/**
 * @brief   Wait end of data transaction and performs finalizations.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] n         number of blocks in transaction
 * @param[in] resp      pointer to the response buffer
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 */
static bool_t sdc_lld_wait_transaction_end(SDCDriver *sdcp, uint32_t n,
                                           uint32_t *resp) {

  /* Note the mask is checked before going to sleep because the interrupt
     may have occurred before reaching the critical zone.*/
  chSysLock();
  if (SDIO->MASK != 0) {
    chDbgAssert(sdcp->thread == NULL,
                "sdc_lld_start_data_transaction(), #1", "not NULL");
    sdcp->thread = chThdSelf();
    chSchGoSleepS(THD_STATE_SUSPENDED);
    chDbgAssert(sdcp->thread == NULL,
                "sdc_lld_start_data_transaction(), #2", "not NULL");
  }
  if ((SDIO->STA & SDIO_STA_DATAEND) == 0) {
    chSysUnlock();
    return CH_FAILED;
  }

#if (defined(STM32F4XX) || defined(STM32F2XX))
  /* Wait until DMA channel enabled to be sure that all data transferred.*/
  while (sdcp->dma->stream->CR & STM32_DMA_CR_EN)
    ;

  /* DMA event flags must be manually cleared.*/
  dmaStreamClearInterrupt(sdcp->dma);

  SDIO->ICR = STM32_SDIO_ICR_ALL_FLAGS;
  SDIO->DCTRL = 0;
  chSysUnlock();

  /* Wait until interrupt flags to be cleared.*/
  /*while (((DMA2->LISR) >> (sdcp->dma->ishift)) & STM32_DMA_ISR_TCIF)
    dmaStreamClearInterrupt(sdcp->dma);*/
#else
  /* Waits for transfer completion at DMA level, the the stream is
     disabled and cleared.*/
  dmaWaitCompletion(sdcp->dma);

  SDIO->ICR = STM32_SDIO_ICR_ALL_FLAGS;
  SDIO->DCTRL = 0;
  chSysUnlock();
#endif

  /* Finalize transaction.*/
  if (n > 1)
    return sdc_lld_send_cmd_short_crc(sdcp, MMCSD_CMD_STOP_TRANSMISSION, 0, resp);

  return CH_SUCCESS;
}

/**
 * @brief   Gets SDC errors.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 *
 * @notapi
 */
static void sdc_lld_collect_errors(SDCDriver *sdcp) {
  uint32_t errors = SDC_NO_ERROR;

  if (SDIO->STA & SDIO_STA_CCRCFAIL) {
    SDIO->ICR |= SDIO_ICR_CCRCFAILC;
    errors |= SDC_CMD_CRC_ERROR;
  }
  if (SDIO->STA & SDIO_STA_DCRCFAIL) {
    SDIO->ICR |= SDIO_ICR_DCRCFAILC;
    errors |= SDC_DATA_CRC_ERROR;
  }
  if (SDIO->STA & SDIO_STA_CTIMEOUT) {
    SDIO->ICR |= SDIO_ICR_CTIMEOUTC;
    errors |= SDC_COMMAND_TIMEOUT;
  }
  if (SDIO->STA & SDIO_STA_DTIMEOUT) {
    SDIO->ICR |= SDIO_ICR_CTIMEOUTC;
    errors |= SDC_DATA_TIMEOUT;
  }
  if (SDIO->STA & SDIO_STA_TXUNDERR) {
    SDIO->ICR |= SDIO_ICR_TXUNDERRC;
    errors |= SDC_TX_UNDERRUN;
  }
  if (SDIO->STA & SDIO_STA_RXOVERR) {
    SDIO->ICR |= SDIO_ICR_RXOVERRC;
    errors |= SDC_RX_OVERRUN;
  }
  if (SDIO->STA & SDIO_STA_STBITERR) {
    SDIO->ICR |= SDIO_ICR_STBITERRC;
    errors |= SDC_STARTBIT_ERROR;
  }

  sdcp->errors |= errors;
}

/**
 * @brief   Performs clean transaction stopping in case of errors.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] n         number of blocks in transaction
 * @param[in] resp      pointer to the response buffer
 *
 * @notapi
 */
static void sdc_lld_error_cleanup(SDCDriver *sdcp,
                                  uint32_t n,
                                  uint32_t *resp) {

  dmaStreamClearInterrupt(sdcp->dma);
  dmaStreamDisable(sdcp->dma);
  SDIO->ICR   = STM32_SDIO_ICR_ALL_FLAGS;
  SDIO->MASK  = 0;
  SDIO->DCTRL = 0;
  sdc_lld_collect_errors(sdcp);
  if (n > 1)
    sdc_lld_send_cmd_short_crc(sdcp, MMCSD_CMD_STOP_TRANSMISSION, 0, resp);
}

/*===========================================================================*/
/* Driver interrupt handlers.                                                */
/*===========================================================================*/

#if !defined(STM32_SDIO_HANDLER)
#error "STM32_SDIO_HANDLER not defined"
#endif
/**
 * @brief   SDIO IRQ handler.
 * @details It just wakes transaction thread. All error  handling performs in
 *          that thread.
 *
 * @isr
 */
CH_IRQ_HANDLER(STM32_SDIO_HANDLER) {

  CH_IRQ_PROLOGUE();

  chSysLockFromIsr()

  /* Disables the source but the status flags are not reset because the
     read/write functions needs to check them.*/
  SDIO->MASK = 0;

  if (SDCD1.thread != NULL) {
    chSchReadyI(SDCD1.thread);
    SDCD1.thread = NULL;
  }

  chSysUnlockFromIsr();

  CH_IRQ_EPILOGUE();
}

/*===========================================================================*/
/* Driver exported functions.                                                */
/*===========================================================================*/

/**
 * @brief   Low level SDC driver initialization.
 *
 * @notapi
 */
void sdc_lld_init(void) {

  sdcObjectInit(&SDCD1);
  SDCD1.thread = NULL;
  SDCD1.dma    = STM32_DMA_STREAM(STM32_SDC_SDIO_DMA_STREAM);
#if CH_DBG_ENABLE_ASSERTS
  SDCD1.sdio   = SDIO;
#endif
}

/**
 * @brief   Configures and activates the SDC peripheral.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 *
 * @notapi
 */
void sdc_lld_start(SDCDriver *sdcp) {

  sdcp->dmamode = STM32_DMA_CR_CHSEL(DMA_CHANNEL) |
                  STM32_DMA_CR_PL(STM32_SDC_SDIO_DMA_PRIORITY) |
                  STM32_DMA_CR_PSIZE_WORD |
                  STM32_DMA_CR_MSIZE_WORD |
                  STM32_DMA_CR_MINC;

#if (defined(STM32F4XX) || defined(STM32F2XX))
  sdcp->dmamode |= STM32_DMA_CR_PFCTRL |
                   STM32_DMA_CR_PBURST_INCR4 |
                   STM32_DMA_CR_MBURST_INCR4;
#endif

  if (sdcp->state == BLK_STOP) {
    /* Note, the DMA must be enabled before the IRQs.*/
    bool_t b;
    b = dmaStreamAllocate(sdcp->dma, STM32_SDC_SDIO_IRQ_PRIORITY, NULL, NULL);
    chDbgAssert(!b, "i2c_lld_start(), #3", "stream already allocated");
    dmaStreamSetPeripheral(sdcp->dma, &SDIO->FIFO);
#if (defined(STM32F4XX) || defined(STM32F2XX))
    dmaStreamSetFIFO(sdcp->dma, STM32_DMA_FCR_DMDIS | STM32_DMA_FCR_FTH_FULL);
#endif
    nvicEnableVector(STM32_SDIO_NUMBER,
                     CORTEX_PRIORITY_MASK(STM32_SDC_SDIO_IRQ_PRIORITY));
    rccEnableSDIO(FALSE);
  }

  /* Configuration, card clock is initially stopped.*/
  SDIO->POWER  = 0;
  SDIO->CLKCR  = 0;
  SDIO->DCTRL  = 0;
  SDIO->DTIMER = 0;
}

/**
 * @brief   Deactivates the SDC peripheral.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 *
 * @notapi
 */
void sdc_lld_stop(SDCDriver *sdcp) {

  if (sdcp->state != BLK_STOP) {

    /* SDIO deactivation.*/
    SDIO->POWER  = 0;
    SDIO->CLKCR  = 0;
    SDIO->DCTRL  = 0;
    SDIO->DTIMER = 0;

    /* Clock deactivation.*/
    nvicDisableVector(STM32_SDIO_NUMBER);
    dmaStreamRelease(sdcp->dma);
    rccDisableSDIO(FALSE);
  }
}

/**
 * @brief   Starts the SDIO clock and sets it to init mode (400kHz or less).
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 *
 * @notapi
 */
void sdc_lld_start_clk(SDCDriver *sdcp) {

  (void)sdcp;

  /* Initial clock setting: 400kHz, 1bit mode.*/
  SDIO->CLKCR  = STM32_SDIO_DIV_LS;
  SDIO->POWER |= SDIO_POWER_PWRCTRL_0 | SDIO_POWER_PWRCTRL_1;
  SDIO->CLKCR |= SDIO_CLKCR_CLKEN;
}

/**
 * @brief   Sets the SDIO clock to data mode (25MHz or less).
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 *
 * @notapi
 */
void sdc_lld_set_data_clk(SDCDriver *sdcp) {

  (void)sdcp;

  SDIO->CLKCR = (SDIO->CLKCR & 0xFFFFFF00) | STM32_SDIO_DIV_HS;
}

/**
 * @brief   Stops the SDIO clock.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 *
 * @notapi
 */
void sdc_lld_stop_clk(SDCDriver *sdcp) {

  (void)sdcp;

  SDIO->CLKCR = 0;
  SDIO->POWER = 0;
}

/**
 * @brief   Switches the bus to 4 bits mode.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] mode      bus mode
 *
 * @notapi
 */
void sdc_lld_set_bus_mode(SDCDriver *sdcp, sdcbusmode_t mode) {
  uint32_t clk = SDIO->CLKCR & ~SDIO_CLKCR_WIDBUS;

  (void)sdcp;

  switch (mode) {
  case SDC_MODE_1BIT:
    SDIO->CLKCR = clk;
    break;
  case SDC_MODE_4BIT:
    SDIO->CLKCR = clk | SDIO_CLKCR_WIDBUS_0;
    break;
  case SDC_MODE_8BIT:
    SDIO->CLKCR = clk | SDIO_CLKCR_WIDBUS_1;
    break;
  }
}

/**
 * @brief   Sends an SDIO command with no response expected.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] cmd       card command
 * @param[in] arg       command argument
 *
 * @notapi
 */
void sdc_lld_send_cmd_none(SDCDriver *sdcp, uint8_t cmd, uint32_t arg) {

  (void)sdcp;

  SDIO->ARG = arg;
  SDIO->CMD = (uint32_t)cmd | SDIO_CMD_CPSMEN;
  while ((SDIO->STA & SDIO_STA_CMDSENT) == 0)
    ;
  SDIO->ICR = SDIO_ICR_CMDSENTC;
}

/**
 * @brief   Sends an SDIO command with a short response expected.
 * @note    The CRC is not verified.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] cmd       card command
 * @param[in] arg       command argument
 * @param[out] resp     pointer to the response buffer (one word)
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
bool_t sdc_lld_send_cmd_short(SDCDriver *sdcp, uint8_t cmd, uint32_t arg,
                              uint32_t *resp) {
  uint32_t sta;

  (void)sdcp;

  SDIO->ARG = arg;
  SDIO->CMD = (uint32_t)cmd | SDIO_CMD_WAITRESP_0 | SDIO_CMD_CPSMEN;
  while (((sta = SDIO->STA) & (SDIO_STA_CMDREND | SDIO_STA_CTIMEOUT |
                               SDIO_STA_CCRCFAIL)) == 0)
    ;
  SDIO->ICR = SDIO_ICR_CMDRENDC | SDIO_ICR_CTIMEOUTC | SDIO_ICR_CCRCFAILC;
  if ((sta & (SDIO_STA_CTIMEOUT)) != 0) {
    sdc_lld_collect_errors(sdcp);
    return CH_FAILED;
  }
  *resp = SDIO->RESP1;
  return CH_SUCCESS;
}

/**
 * @brief   Sends an SDIO command with a short response expected and CRC.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] cmd       card command
 * @param[in] arg       command argument
 * @param[out] resp     pointer to the response buffer (one word)
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
bool_t sdc_lld_send_cmd_short_crc(SDCDriver *sdcp, uint8_t cmd, uint32_t arg,
                                  uint32_t *resp) {
  uint32_t sta;

  (void)sdcp;

  SDIO->ARG = arg;
  SDIO->CMD = (uint32_t)cmd | SDIO_CMD_WAITRESP_0 | SDIO_CMD_CPSMEN;
  while (((sta = SDIO->STA) & (SDIO_STA_CMDREND | SDIO_STA_CTIMEOUT |
                               SDIO_STA_CCRCFAIL)) == 0)
    ;
  SDIO->ICR = SDIO_ICR_CMDRENDC | SDIO_ICR_CTIMEOUTC | SDIO_ICR_CCRCFAILC;
  if ((sta & (SDIO_STA_CTIMEOUT | SDIO_STA_CCRCFAIL)) != 0) {
    sdc_lld_collect_errors(sdcp);
    return CH_FAILED;
  }
  *resp = SDIO->RESP1;
  return CH_SUCCESS;
}

/**
 * @brief   Sends an SDIO command with a long response expected and CRC.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] cmd       card command
 * @param[in] arg       command argument
 * @param[out] resp     pointer to the response buffer (four words)
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
bool_t sdc_lld_send_cmd_long_crc(SDCDriver *sdcp, uint8_t cmd, uint32_t arg,
                                 uint32_t *resp) {
  uint32_t sta;

  (void)sdcp;

  SDIO->ARG = arg;
  SDIO->CMD = (uint32_t)cmd | SDIO_CMD_WAITRESP_0 | SDIO_CMD_WAITRESP_1 |
                              SDIO_CMD_CPSMEN;
  while (((sta = SDIO->STA) & (SDIO_STA_CMDREND | SDIO_STA_CTIMEOUT |
                               SDIO_STA_CCRCFAIL)) == 0)
    ;
  SDIO->ICR = SDIO_ICR_CMDRENDC | SDIO_ICR_CTIMEOUTC | SDIO_ICR_CCRCFAILC;
  if ((sta & (STM32_SDIO_STA_ERROR_MASK)) != 0) {
    sdc_lld_collect_errors(sdcp);
    return CH_FAILED;
  }
  /* Save bytes in reverse order because MSB in response comes first.*/
  *resp++ = SDIO->RESP4;
  *resp++ = SDIO->RESP3;
  *resp++ = SDIO->RESP2;
  *resp   = SDIO->RESP1;
  return CH_SUCCESS;
}

/**
 * @brief   Reads one or more blocks.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] startblk  first block to read
 * @param[out] buf      pointer to the read buffer
 * @param[in] n         number of blocks to read
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
bool_t sdc_lld_read_aligned(SDCDriver *sdcp, uint32_t startblk,
                            uint8_t *buf, uint32_t n) {
  uint32_t resp[1];

  chDbgCheck((n < (0x1000000 / MMCSD_BLOCK_SIZE)), "max transaction size");

  SDIO->DTIMER = STM32_SDC_READ_TIMEOUT;

  /* Checks for errors and waits for the card to be ready for reading.*/
  if (_sdc_wait_for_transfer_state(sdcp))
    return CH_FAILED;

  /* Prepares the DMA channel for writing.*/
  dmaStreamSetMemory0(sdcp->dma, buf);
  dmaStreamSetTransactionSize(sdcp->dma,
                              (n * MMCSD_BLOCK_SIZE) / sizeof (uint32_t));
  dmaStreamSetMode(sdcp->dma, sdcp->dmamode | STM32_DMA_CR_DIR_P2M);
  dmaStreamEnable(sdcp->dma);

  /* Setting up data transfer.*/
  SDIO->ICR   = STM32_SDIO_ICR_ALL_FLAGS;
  SDIO->MASK  = SDIO_MASK_DCRCFAILIE |
                SDIO_MASK_DTIMEOUTIE |
                SDIO_MASK_STBITERRIE |
                SDIO_MASK_RXOVERRIE |
                SDIO_MASK_DATAENDIE;
  SDIO->DLEN  = n * MMCSD_BLOCK_SIZE;

  /* Talk to card what we want from it.*/
  if (sdc_lld_prepare_read(sdcp, startblk, n, resp) == TRUE)
    goto error;

  /* Transaction starts just after DTEN bit setting.*/
  SDIO->DCTRL = SDIO_DCTRL_DTDIR |
                SDIO_DCTRL_DBLOCKSIZE_3 |
                SDIO_DCTRL_DBLOCKSIZE_0 |
                SDIO_DCTRL_DMAEN |
                SDIO_DCTRL_DTEN;
  if (sdc_lld_wait_transaction_end(sdcp, n, resp) == TRUE)
    goto error;

  return CH_SUCCESS;

error:
  sdc_lld_error_cleanup(sdcp, n, resp);
  return CH_FAILED;
}

/**
 * @brief   Writes one or more blocks.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] startblk  first block to write
 * @param[out] buf      pointer to the write buffer
 * @param[in] n         number of blocks to write
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
bool_t sdc_lld_write_aligned(SDCDriver *sdcp, uint32_t startblk,
                             const uint8_t *buf, uint32_t n) {
  uint32_t resp[1];

  chDbgCheck((n < (0x1000000 / MMCSD_BLOCK_SIZE)), "max transaction size");

  SDIO->DTIMER = STM32_SDC_WRITE_TIMEOUT;

  /* Checks for errors and waits for the card to be ready for writing.*/
  if (_sdc_wait_for_transfer_state(sdcp))
    return CH_FAILED;

  /* Prepares the DMA channel for writing.*/
  dmaStreamSetMemory0(sdcp->dma, buf);
  dmaStreamSetTransactionSize(sdcp->dma,
                              (n * MMCSD_BLOCK_SIZE) / sizeof (uint32_t));
  dmaStreamSetMode(sdcp->dma, sdcp->dmamode | STM32_DMA_CR_DIR_M2P);
  dmaStreamEnable(sdcp->dma);

  /* Setting up data transfer.*/
  SDIO->ICR   = STM32_SDIO_ICR_ALL_FLAGS;
  SDIO->MASK  = SDIO_MASK_DCRCFAILIE |
                SDIO_MASK_DTIMEOUTIE |
                SDIO_MASK_STBITERRIE |
                SDIO_MASK_TXUNDERRIE |
                SDIO_MASK_DATAENDIE;
  SDIO->DLEN  = n * MMCSD_BLOCK_SIZE;

  /* Talk to card what we want from it.*/
  if (sdc_lld_prepare_write(sdcp, startblk, n, resp) == TRUE)
    goto error;

  /* Transaction starts just after DTEN bit setting.*/
  SDIO->DCTRL = SDIO_DCTRL_DBLOCKSIZE_3 |
                SDIO_DCTRL_DBLOCKSIZE_0 |
                SDIO_DCTRL_DMAEN |
                SDIO_DCTRL_DTEN;
  if (sdc_lld_wait_transaction_end(sdcp, n, resp) == TRUE)
    goto error;

  return CH_SUCCESS;

error:
  sdc_lld_error_cleanup(sdcp, n, resp);
  return CH_FAILED;
}

/**
 * @brief   Reads one or more blocks.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] startblk  first block to read
 * @param[out] buf      pointer to the read buffer
 * @param[in] n         number of blocks to read
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
bool_t sdc_lld_read(SDCDriver *sdcp, uint32_t startblk,
                    uint8_t *buf, uint32_t n) {

#if STM32_SDC_SDIO_UNALIGNED_SUPPORT
  if (((unsigned)buf & 3) != 0) {
    uint32_t i;
    for (i = 0; i < n; i++) {
      if (sdc_lld_read_aligned(sdcp, startblk, u.buf, 1))
        return CH_FAILED;
      memcpy(buf, u.buf, MMCSD_BLOCK_SIZE);
      buf += MMCSD_BLOCK_SIZE;
      startblk++;
    }
    return CH_SUCCESS;
  }
#endif /* STM32_SDC_SDIO_UNALIGNED_SUPPORT */
  return sdc_lld_read_aligned(sdcp, startblk, buf, n);
}

/**
 * @brief   Writes one or more blocks.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 * @param[in] startblk  first block to write
 * @param[out] buf      pointer to the write buffer
 * @param[in] n         number of blocks to write
 *
 * @return              The operation status.
 * @retval CH_SUCCESS  operation succeeded.
 * @retval CH_FAILED    operation failed.
 *
 * @notapi
 */
bool_t sdc_lld_write(SDCDriver *sdcp, uint32_t startblk,
                     const uint8_t *buf, uint32_t n) {

#if STM32_SDC_SDIO_UNALIGNED_SUPPORT
  if (((unsigned)buf & 3) != 0) {
    uint32_t i;
    for (i = 0; i < n; i++) {
      memcpy(u.buf, buf, MMCSD_BLOCK_SIZE);
      buf += MMCSD_BLOCK_SIZE;
      if (sdc_lld_write_aligned(sdcp, startblk, u.buf, 1))
        return CH_FAILED;
      startblk++;
    }
    return CH_SUCCESS;
  }
#endif /* STM32_SDC_SDIO_UNALIGNED_SUPPORT */
  return sdc_lld_write_aligned(sdcp, startblk, buf, n);
}

/**
 * @brief   Waits for card idle condition.
 *
 * @param[in] sdcp      pointer to the @p SDCDriver object
 *
 * @return              The operation status.
 * @retval CH_SUCCESS   the operation succeeded.
 * @retval CH_FAILED    the operation failed.
 *
 * @api
 */
bool_t sdc_lld_sync(SDCDriver *sdcp) {

  /* TODO: Implement.*/
  (void)sdcp;
  return CH_SUCCESS;
}

#endif /* HAL_USE_SDC */

/** @} */