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87f134cfaa
Nuttx currently has 2 types of sleep interfaces: 1. Signal-scheduled sleep: nxsig_sleep() / nxsig_usleep() / nxsig_nanosleep() Weaknesses: a. Signal-dependent: The signal-scheduled sleep method is bound to the signal framework, while some driver sleep operations do not depend on signals. b. Timespec conversion: Signal-scheduled sleep involves timespec conversion, which has a significant impact on performance. 2. Busy sleep: up_mdelay() / up_udelay() Weaknesses: a. Does not actively trigger scheduling, occupy the CPU loading. 3. New interfaces: Scheduled sleep: nxsched_sleep() / nxsched_usleep() / nxsched_msleep() / nxsched_ticksleep() Strengths: a. Does not depend on the signal framework. b. Tick-based, without additional computational overhead. Currently, the Nuttx driver framework extensively uses nxsig_* interfaces. However, the driver does not need to rely on signals or timespec conversion. Therefore, a new set of APIs is added to reduce dependencies on other modules. (This PR also aims to make signals optional, further reducing the code size of Nuttx.) Signed-off-by: chao an <anchao.archer@bytedance.com>
145 lines
4.2 KiB
C
145 lines
4.2 KiB
C
/****************************************************************************
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* drivers/spi/spi_transfer.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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/signal.h>
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#include <nuttx/spi/spi.h>
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#include <nuttx/spi/spi_transfer.h>
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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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SPI_SETFREQUENCY(spi, seq->frequency);
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#ifdef CONFIG_SPI_DELAY_CONTROL
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ret = SPI_SETDELAY(spi, seq->a, seq->b, seq->c, seq->i);
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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, (enum spi_mode_e)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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nxsched_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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