spi_lld.c
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/*
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/>.
---
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes ChibiOS/RT, without being obliged to provide
the source code for any proprietary components. See the file exception.txt
for full details of how and when the exception can be applied.
*/
/**
* @file STM8S/spi_lld.c
* @brief STM8S low level SPI driver code.
*
* @addtogroup SPI
* @{
*/
#include "ch.h"
#include "hal.h"
#if HAL_USE_SPI || defined(__DOXYGEN__)
/*===========================================================================*/
/* Driver exported variables. */
/*===========================================================================*/
#if STM8S_SPI_USE_SPI || defined(__DOXYGEN__)
/** @brief SPI1 driver identifier.*/
SPIDriver SPID1;
#endif
/*===========================================================================*/
/* Driver local variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver local functions. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver interrupt handlers. */
/*===========================================================================*/
#if STM8S_SPI_USE_SPI || defined(__DOXYGEN__)
/**
* @brief IRQ 10 service routine.
*
* @isr
*/
CH_IRQ_HANDLER(10) {
CH_IRQ_PROLOGUE();
if ((SPI->SR & SPI_SR_OVR) != 0) {
/* The overflow condition should never happen because priority is given
to receive but a hook macro is provided anyway...*/
STM8S_SPI_ERROR_HOOK(&SPID1);
}
/* Handling the DR register like it is a FIFO with depth>1 in order to
handle the case where a frame arrives immediately after reading the
DR register.*/
while ((SPI->SR & SPI_SR_RXNE) != 0) {
if (SPID1.rxptr != NULL)
*SPID1.rxptr++ = SPI->DR;
else
(void)SPI->DR;
if (--SPID1.rxcnt == 0) {
chDbgAssert(SPID1.txcnt == 0,
"IRQ10, #1", "counter out of synch");
/* Stops all the IRQ sources.*/
SPI->ICR = 0;
/* Portable SPI ISR code defined in the high level driver, note, it
is a macro.*/
_spi_isr_code(&SPID1);
/* Goto because it is mandatory to go through the epilogue, cannot
just return.*/
goto exit_isr;
}
}
/* Loading the DR register.*/
if ((SPI->SR & SPI_SR_TXE) != 0) {
if (SPID1.txptr != NULL)
SPI->DR = *SPID1.txptr++;
else
SPI->DR = 0xFF;
}
exit_isr:
CH_IRQ_EPILOGUE();
}
#endif
/*===========================================================================*/
/* Driver exported functions. */
/*===========================================================================*/
/**
* @brief Low level SPI driver initialization.
*
* @notapi
*/
void spi_lld_init(void) {
#if STM8S_SPI_USE_SPI
spiObjectInit(&SPID1);
#endif /* STM8S_SPI_USE_SPI */
}
/**
* @brief Configures and activates the SPI peripheral.
*
* @param[in] spip pointer to the @p SPIDriver object
*
* @notapi
*/
void spi_lld_start(SPIDriver *spip) {
/* Clock activation.*/
CLK->PCKENR1 |= CLK_PCKENR1_SPI; /* PCKEN11, clock source. */
/* Configuration.*/
SPI->CR1 = 0;
SPI->CR1 = spip->config->cr1 | SPI_CR1_MSTR;
SPI->CR2 = SPI_CR2_SSI | SPI_CR2_SSM;
SPI->CR1 |= SPI_CR1_SPE;
}
/**
* @brief Deactivates the SPI peripheral.
*
* @param[in] spip pointer to the @p SPIDriver object
*
* @notapi
*/
void spi_lld_stop(SPIDriver *spip) {
(void)spip;
/* Reset state.*/
SPI->CR1 = 0;
SPI->CR2 = 0;
SPI->ICR = 0;
/* Clock de-activation.*/
CLK->PCKENR1 &= (uint8_t)~CLK_PCKENR1_SPI; /* PCKEN11, clock source. */
}
/**
* @brief Asserts the slave select signal and prepares for transfers.
*
* @param[in] spip pointer to the @p SPIDriver object
*
* @notapi
*/
void spi_lld_select(SPIDriver *spip) {
palClearPad(spip->config->ssport, spip->config->sspad);
}
/**
* @brief Deasserts the slave select signal.
* @details The previously selected peripheral is unselected.
*
* @param[in] spip pointer to the @p SPIDriver object
*
* @notapi
*/
void spi_lld_unselect(SPIDriver *spip) {
palSetPad(spip->config->ssport, spip->config->sspad);
}
/**
* @brief Ignores data on the SPI bus.
* @details This function transmits a series of idle words on the SPI bus and
* ignores the received data. This function can be invoked even
* when a slave select signal has not been yet asserted.
*
* @param[in] spip pointer to the @p SPIDriver object
* @param[in] n number of words to be ignored
*
* @notapi
*/
void spi_lld_ignore(SPIDriver *spip, size_t n) {
spip->rxptr = NULL;
spip->txptr = NULL;
spip->rxcnt = spip->txcnt = n;
SPI->ICR = SPI_ICR_TXEI | SPI_ICR_RXEI | SPI_ICR_ERRIE;
}
/**
* @brief Exchanges data on the SPI bus.
* @details This asynchronous function starts a simultaneous transmit/receive
* operation.
* @post At the end of the operation the configured callback is invoked.
* @note The buffers are organized as uint8_t arrays for data sizes below or
* equal to 8 bits else it is organized as uint16_t arrays.
*
* @param[in] spip pointer to the @p SPIDriver object
* @param[in] n number of words to be exchanged
* @param[in] txbuf the pointer to the transmit buffer
* @param[out] rxbuf the pointer to the receive buffer
*
* @notapi
*/
void spi_lld_exchange(SPIDriver *spip, size_t n,
const void *txbuf, void *rxbuf) {
spip->rxptr = rxbuf;
spip->txptr = txbuf;
spip->rxcnt = spip->txcnt = n;
SPI->ICR = SPI_ICR_TXEI | SPI_ICR_RXEI | SPI_ICR_ERRIE;
}
/**
* @brief Sends data over the SPI bus.
* @details This asynchronous function starts a transmit operation.
* @post At the end of the operation the configured callback is invoked.
* @note The buffers are organized as uint8_t arrays for data sizes below or
* equal to 8 bits else it is organized as uint16_t arrays.
*
* @param[in] spip pointer to the @p SPIDriver object
* @param[in] n number of words to send
* @param[in] txbuf the pointer to the transmit buffer
*
* @notapi
*/
void spi_lld_send(SPIDriver *spip, size_t n, const void *txbuf) {
spip->rxptr = NULL;
spip->txptr = txbuf;
spip->rxcnt = spip->txcnt = n;
SPI->ICR = SPI_ICR_TXEI | SPI_ICR_RXEI | SPI_ICR_ERRIE;
}
/**
* @brief Receives data from the SPI bus.
* @details This asynchronous function starts a receive operation.
* @post At the end of the operation the configured callback is invoked.
* @note The buffers are organized as uint8_t arrays for data sizes below or
* equal to 8 bits else it is organized as uint16_t arrays.
*
* @param[in] spip pointer to the @p SPIDriver object
* @param[in] n number of words to receive
* @param[out] rxbuf the pointer to the receive buffer
*
* @notapi
*/
void spi_lld_receive(SPIDriver *spip, size_t n, void *rxbuf) {
spip->rxptr = rxbuf;
spip->txptr = NULL;
spip->rxcnt = spip->txcnt = n;
SPI->ICR = SPI_ICR_TXEI | SPI_ICR_RXEI | SPI_ICR_ERRIE;
}
/**
* @brief Exchanges one frame using a polled wait.
* @details This synchronous function exchanges one frame using a polled
* synchronization method. This function is useful when exchanging
* small amount of data on high speed channels, usually in this
* situation is much more efficient just wait for completion using
* polling than suspending the thread waiting for an interrupt.
*
* @param[in] spip pointer to the @p SPIDriver object
* @param[in] frame the data frame to send over the SPI bus
* @return The received data frame from the SPI bus.
*/
uint8_t spi_lld_polled_exchange(SPIDriver *spip, uint8_t frame) {
(void)spip;
SPI->DR = (uint32_t)frame;
while ((SPI->SR & SPI_SR_RXNE) == 0)
;
return (uint16_t)SPI->DR;
}
#endif /* HAL_USE_SPI */
/** @} */