227 lines
7.1 KiB
C
227 lines
7.1 KiB
C
/*
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ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.
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This file is part of ChibiOS/RT.
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ChibiOS/RT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/RT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file AT91SAM7/spi_lld.c
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* @brief AT91SAM7 low level SPI driver code.
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* @addtogroup AT91SAM7_SPI
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* @{
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*/
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#include "ch.h"
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#include "hal.h"
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#if CH_HAL_USE_SPI || defined(__DOXYGEN__)
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/*===========================================================================*/
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/* Driver exported variables. */
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/*===========================================================================*/
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#if USE_AT91SAM7_SPI || defined(__DOXYGEN__)
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/** @brief SPI driver identifier.*/
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SPIDriver SPID;
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#endif
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/*===========================================================================*/
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/* Driver local variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Driver local functions. */
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/*===========================================================================*/
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/**
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* @brief Synchronous SPI transfer.
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*
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* @param[in] n number of bytes to be exchanged
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*
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* @param[in] txbuf the pointer to the transmit buffer or @p NULL
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* @param[out] rxbuf the pointer to the receive buffer or @p NULL
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*/
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void rw8(size_t n, const uint8_t *txbuf, uint8_t *rxbuf) {
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size_t ntx = n;
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while (n > 0) {
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uint32_t sr = AT91C_BASE_SPI->SPI_SR;
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if (sr & AT91C_SPI_RDRF) {
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uint8_t w = AT91C_BASE_SPI->SPI_RDR;
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if (rxbuf != NULL)
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*rxbuf++ = w;
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n--;
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continue; /* Priority over transmission. */
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}
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if ((ntx > 0) && (sr & AT91C_SPI_TDRE)) {
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if (txbuf != NULL)
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AT91C_BASE_SPI->SPI_TDR = *txbuf++;
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else
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AT91C_BASE_SPI->SPI_TDR = 0xFF;
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ntx--;
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}
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}
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}
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/*===========================================================================*/
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/* Driver interrupt handlers. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Driver exported functions. */
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/*===========================================================================*/
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/**
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* @brief Low level SPI driver initialization.
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*/
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void spi_lld_init(void) {
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#if USE_AT91SAM7_SPI
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spiObjectInit(&SPID);
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#endif
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}
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/**
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* @brief Configures and activates the SPI peripheral.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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*/
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void spi_lld_start(SPIDriver *spip) {
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if (spip->spd_state == SPI_STOP) {
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/* disable general-purpose I/O for SPI pins */
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AT91C_BASE_PIOA->PIO_PDR = SPI_MISO | SPI_MOSI | SPI_SCK;
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/* select perepheral A for SPI pins*/
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AT91C_BASE_PIOA->PIO_ASR = SPI_MISO | SPI_MOSI | SPI_SCK;
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/* Clock activation.*/
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AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_SPI);
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}
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/* software reset must be written twice (errata for revision B parts) */
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AT91C_BASE_SPI->SPI_CR = AT91C_SPI_SWRST;
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AT91C_BASE_SPI->SPI_CR = AT91C_SPI_SWRST;
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/* Configuration.*/
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AT91C_BASE_SPI->SPI_MR = spip->spd_config->spc_mr;
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AT91C_BASE_SPI->SPI_CSR[MMC_CSR_NUM] = spip->spd_config->spc_csr;
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/* Enable SPI */
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AT91C_BASE_SPI->SPI_CR = AT91C_SPI_SPIEN;
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}
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/**
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* @brief Deactivates the SPI peripheral.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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*/
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void spi_lld_stop(SPIDriver *spip) {
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if (spip->spd_state != SPI_STOP) {
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/* disable SPI */
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AT91C_BASE_SPI->SPI_CR = AT91C_SPI_SPIDIS;
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/* disable clocks to SPI perepheral */
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AT91C_BASE_PMC->PMC_PCDR = (1 << AT91C_ID_SPI);
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}
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}
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/**
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* @brief Asserts the slave select signal and prepares for transfers.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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*/
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void spi_lld_select(SPIDriver *spip) {
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palClearPad(spip->spd_config->spc_ssport, spip->spd_config->spc_sspad);
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}
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/**
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* @brief Deasserts the slave select signal.
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* @details The previously selected peripheral is unselected.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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*/
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void spi_lld_unselect(SPIDriver *spip) {
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palSetPad(spip->spd_config->spc_ssport, spip->spd_config->spc_sspad);
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}
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/**
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* @brief Ignores data on the SPI bus.
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* @details This function transmits a series of idle words on the SPI bus and
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* ignores the received data. This function can be invoked even
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* when a slave select signal has not been yet asserted.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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* @param[in] n number of words to be ignored
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*/
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void spi_lld_ignore(SPIDriver *spip, size_t n) {
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(void)spip;
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rw8(n, NULL, NULL);
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}
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/**
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* @brief Exchanges data on the SPI bus.
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* @details This function performs a simultaneous transmit/receive operation.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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* @param[in] n number of words to be exchanged
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* @param[in] txbuf the pointer to the transmit buffer
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* @param[out] rxbuf the pointer to the receive buffer
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*
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* @note The buffers are organized as uint8_t arrays for data sizes below or
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* equal to 8 bits else it is organized as uint16_t arrays.
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*/
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void spi_lld_exchange(SPIDriver *spip, size_t n,
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const void *txbuf, void *rxbuf) {
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(void)spip;
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rw8(n, txbuf, rxbuf);
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}
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/**
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* @brief Sends data over the SPI bus.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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* @param[in] n number of words to send
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* @param[in] txbuf the pointer to the transmit buffer
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*
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* @note The buffers are organized as uint8_t arrays for data sizes below or
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* equal to 8 bits else it is organized as uint16_t arrays.
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*/
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void spi_lld_send(SPIDriver *spip, size_t n, const void *txbuf) {
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(void)spip;
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rw8(n, txbuf, NULL);
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}
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/**
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* @brief Receives data from the SPI bus.
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*
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* @param[in] spip pointer to the @p SPIDriver object
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* @param[in] n number of words to receive
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* @param[out] rxbuf the pointer to the receive buffer
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*
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* @note The buffers are organized as uint8_t arrays for data sizes below or
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* equal to 8 bits else it is organized as uint16_t arrays.
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*/
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void spi_lld_receive(SPIDriver *spip, size_t n, void *rxbuf) {
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(void)spip;
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rw8(n, NULL, rxbuf);
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}
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#endif /* CH_HAL_USE_SPI */
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/** @} */
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