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- /****************************************************************************
- * drivers/spi/spi_transfer.c
- *
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership. The
- * ASF licenses this file to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance with the
- * License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
- * under the License.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <unistd.h>
- #include <assert.h>
- #include <errno.h>
- #include <debug.h>
- #include <nuttx/signal.h>
- #include <nuttx/spi/spi.h>
- #include <nuttx/spi/spi_transfer.h>
- #ifdef CONFIG_SPI_EXCHANGE
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: spi_transfer
- *
- * Description:
- * This is a helper function that can be used to encapsulate and manage
- * a sequence of SPI transfers. The SPI bus will be locked and the
- * SPI device selected for the duration of the transfers.
- *
- * Input Parameters:
- * spi - An instance of the SPI device to use for the transfer
- * seq - Describes the sequence of transfers.
- *
- * Returned Value:
- * Zero (OK) on success; a negated errno value on failure.
- *
- ****************************************************************************/
- int spi_transfer(FAR struct spi_dev_s *spi, FAR struct spi_sequence_s *seq)
- {
- FAR struct spi_trans_s *trans;
- int ret = OK;
- int i;
- DEBUGASSERT(spi != NULL && seq != NULL && seq->trans != NULL);
- /* Get exclusive access to the SPI bus */
- SPI_LOCK(spi, true);
- /* Establish the fixed SPI attributes for all transfers in the sequence */
- SPI_SETFREQUENCY(spi, seq->frequency);
- #ifdef CONFIG_SPI_CS_DELAY_CONTROL
- ret = SPI_SETDELAY(spi, seq->a, seq->b, seq->c);
- if (ret < 0)
- {
- spierr("ERROR: SPI_SETDELAY failed: %d\n", ret);
- SPI_LOCK(spi, false);
- return ret;
- }
- #endif
- SPI_SETMODE(spi, seq->mode);
- SPI_SETBITS(spi, seq->nbits);
- /* Select the SPI device in preparation for the transfer.
- * REVISIT: This is redundant.
- */
- SPI_SELECT(spi, seq->dev, true);
- /* Then perform each transfer is the sequence */
- for (i = 0, trans = seq->trans; i < (int)seq->ntrans; i++, trans++)
- {
- /* Establish the fixed SPI attributes for unique to this transaction */
- #ifdef CONFIG_SPI_HWFEATURES
- ret = SPI_HWFEATURES(spi, trans->hwfeat);
- if (ret < 0)
- {
- spierr("ERROR: SPI_HWFEATURES failed: %d\n", ret);
- break;
- }
- #endif
- #ifdef CONFIG_SPI_CMDDATA
- ret = SPI_CMDDATA(spi, seq->dev, trans->cmd);
- if (ret < 0)
- {
- spierr("ERROR: SPI_CMDDATA failed: %d\n", ret);
- break;
- }
- #endif
- /* [Re-]select the SPI device in preparation for the transfer */
- SPI_SELECT(spi, seq->dev, true);
- /* Perform the transfer */
- SPI_EXCHANGE(spi, trans->txbuffer, trans->rxbuffer, trans->nwords);
- /* Possibly de-select the SPI device after the transfer */
- if (trans->deselect)
- {
- SPI_SELECT(spi, seq->dev, false);
- }
- /* Perform any requested inter-transfer delay */
- if (trans->delay > 0)
- {
- nxsig_usleep(trans->delay);
- }
- }
- SPI_SELECT(spi, seq->dev, false);
- SPI_LOCK(spi, false);
- return ret;
- }
- #endif /* CONFIG_SPI_EXCHANGE */
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