161 lines
4.9 KiB
C
161 lines
4.9 KiB
C
/****************************************************************************
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* drivers/spi/spi_transfer.c
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*
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* Copyright (C) 2016 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <unistd.h>
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#include <assert.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/spi/spi.h>
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#include <nuttx/spi/spi_transfer.h>
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#ifdef CONFIG_SPI_EXCHANGE
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: spi_transfer
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*
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* Description:
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* This is a helper function that can be used to encapsulate and manage
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* a sequence of SPI transfers. The SPI bus will be locked and the
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* SPI device selected for the duration of the transfers.
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*
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* Input Parameters:
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* spi - An instance of the SPI device to use for the transfer
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* seq - Describes the sequence of transfers.
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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****************************************************************************/
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int spi_transfer(FAR struct spi_dev_s *spi, FAR struct spi_sequence_s *seq)
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{
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FAR struct spi_trans_s *trans;
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int ret = OK;
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int i;
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DEBUGASSERT(spi != NULL && seq != NULL && seq->trans != NULL);
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/* Get exclusive access to the SPI bus */
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SPI_LOCK(spi, true);
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/* Establish the fixed SPI attributes for all transfers in the sequence */
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(void)SPI_SETFREQUENCY(spi, seq->frequency);
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#ifdef CONFIG_SPI_CS_DELAY_CONTROL
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ret = SPI_SETDELAY(spi, seq->a, seq->b, seq->c);
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if (ret < 0)
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{
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spierr("ERROR: SPI_SETDELAY failed: %d\n", ret)
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SPI_LOCK(spi, false);
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return ret;
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}
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#endif
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SPI_SETMODE(spi, seq->mode);
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SPI_SETBITS(spi, seq->nbits);
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/* Select the SPI device in preparation for the transfer.
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* REVISIT: This is redundant.
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*/
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SPI_SELECT(spi, seq->dev, true);
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/* Then perform each transfer is the sequence */
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for (i = 0, trans = seq->trans; i < (int)seq->ntrans; i++, trans++)
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{
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/* Establish the fixed SPI attributes for unique to this transaction */
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#ifdef CONFIG_SPI_HWFEATURES
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ret = SPI_HWFEATURES(spi, trans->hwfeat);
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if (ret < 0)
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{
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spierr("ERROR: SPI_HWFEATURES failed: %d\n", ret)
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break;
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}
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#endif
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#ifdef CONFIG_SPI_CMDDATA
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ret = SPI_CMDDATA(spi, seq->dev, trans->cmd);
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if (ret < 0)
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{
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spierr("ERROR: SPI_CMDDATA failed: %d\n", ret)
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break;
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}
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#endif
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/* [Re-]select the SPI device in preparation for the transfer */
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SPI_SELECT(spi, seq->dev, true);
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/* Perform the transfer */
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SPI_EXCHANGE(spi, trans->txbuffer, trans->rxbuffer, trans->nwords);
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/* Possibly de-select the SPI device after the transfer */
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if (trans->deselect)
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{
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SPI_SELECT(spi, seq->dev, false);
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}
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/* Perform any requested inter-transfer delay */
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if (trans->delay > 0)
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{
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usleep(trans->delay);
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}
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}
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SPI_SELECT(spi, seq->dev, false);
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SPI_LOCK(spi, false);
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return ret;
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}
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#endif /* CONFIG_SPI_EXCHANGE */
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