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tinySA/os/hal/ports/AVR/spi_lld.c

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/*
ChibiOS/RT - Copyright (C) 2006-2014 Giovanni Di Sirio
Licensed 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.
*/
/**
* @file AVR/spi_lld.c
* @brief AVR SPI subsystem low level driver source.
*
* @addtogroup SPI
* @{
*/
#include "hal.h"
#if HAL_USE_SPI || defined(__DOXYGEN__)
/*===========================================================================*/
/* Driver local definitions. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver exported variables. */
/*===========================================================================*/
/**
* @brief SPI1 driver identifier.
*/
#if AVR_SPI_USE_SPI1 || defined(__DOXYGEN__)
SPIDriver SPID1;
#endif
/*===========================================================================*/
/* Driver local variables and types. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver local functions. */
/*===========================================================================*/
/*===========================================================================*/
/* Driver interrupt handlers. */
/*===========================================================================*/
#if AVR_SPI_USE_SPI1 || defined(__DOXYGEN__)
/**
* @brief SPI event interrupt handler.
*
* @notapi
*/
OSAL_IRQ_HANDLER(SPI_STC_vect) {
OSAL_IRQ_PROLOGUE();
SPIDriver *spip = &SPID1;
/* spi_lld_exchange or spi_lld_receive */
if (spip->rxbuf && spip->rxidx < spip->rxbytes) {
spip->rxbuf[spip->rxidx++] = SPDR; // receive
}
/* spi_lld_exchange, spi_lld_send or spi_lld_ignore */
if (spip->txidx < spip->txbytes) {
if (spip->txbuf) {
SPDR = spip->txbuf[spip->txidx++]; // send
} else {
SPDR = 0; spip->txidx++; // dummy send
}
}
/* spi_lld_send */
else if (spip->rxidx < spip->rxbytes) { /* rx not done */
SPDR = 0; // dummy send to keep the clock going
}
/* rx done and tx done */
if (spip->rxidx >= spip->rxbytes && spip->txidx >= spip->txbytes) {
_spi_isr_code(spip);
}
OSAL_IRQ_EPILOGUE();
}
#endif /* AVR_SPI_USE_SPI1 */
/*===========================================================================*/
/* Driver exported functions. */
/*===========================================================================*/
/**
* @brief Low level SPI driver initialization.
*
* @notapi
*/
void spi_lld_init(void) {
#if AVR_SPI_USE_SPI1
/* Driver initialization.*/
spiObjectInit(&SPID1);
#endif /* AVR_SPI_USE_SPI1 */
}
/**
* @brief Configures and activates the SPI peripheral.
*
* @param[in] spip pointer to the @p SPIDriver object
*
* @notapi
*/
void spi_lld_start(SPIDriver *spip) {
uint8_t dummy;
/* Configures the peripheral.*/
if (spip->state == SPI_STOP) {
/* Enables the peripheral.*/
#if AVR_SPI_USE_SPI1
if (&SPID1 == spip) {
/* Enable SPI clock using Power Reduction Register */
#if defined(PRR0)
PRR0 &= ~(1 << PRSPI);
#elif defined(PRR)
PRR &= ~(1 << PRSPI);
#endif
/* SPI enable, SPI interrupt enable */
SPCR |= ((1 << SPE) | (1 << SPIE));
switch (spip->config->role) {
case SPI_ROLE_SLAVE:
SPCR &= ~(1 << MSTR); /* master mode */
DDR_SPI1 |= (1 << SPI1_MISO); /* output */
DDR_SPI1 &= ~((1 << SPI1_MOSI) | (1 << SPI1_SCK) | (1 << SPI1_SS)); /* input */
break;
case SPI_ROLE_MASTER: /* fallthrough */
default:
SPCR |= (1 << MSTR); /* slave mode */
DDR_SPI1 |= ((1 << SPI1_MOSI) | (1 << SPI1_SCK)); /* output */
DDR_SPI1 &= ~(1 << SPI1_MISO); /* input */
spip->config->ssport->dir |= (1 << spip->config->sspad);
}
switch (spip->config->bitorder) {
case SPI_LSB_FIRST:
SPCR |= (1 << DORD);
break;
case SPI_MSB_FIRST: /* fallthrough */
default:
SPCR &= ~(1 << DORD);
break;
}
SPCR &= ~((1 << CPOL) | (1 << CPHA));
switch (spip->config->mode) {
case SPI_MODE_1:
SPCR |= (1 << CPHA);
break;
case SPI_MODE_2:
SPCR |= (1 << CPOL);
break;
case SPI_MODE_3:
SPCR |= ((1 << CPOL) | (1 << CPHA));
break;
case SPI_MODE_0: /* fallthrough */
default: break;
}
SPCR &= ~((1 << SPR1) | (1 << SPR0));
SPSR &= ~(1 << SPI2X);
switch (spip->config->clockrate) {
case SPI_SCK_FOSC_2:
SPSR |= (1 << SPI2X);
break;
case SPI_SCK_FOSC_8:
SPSR |= (1 << SPI2X);
SPCR |= (1 << SPR0);
break;
case SPI_SCK_FOSC_16:
SPCR |= (1 << SPR0);
break;
case SPI_SCK_FOSC_32:
SPSR |= (1 << SPI2X);
SPCR |= (1 << SPR1);
break;
case SPI_SCK_FOSC_64:
SPCR |= (1 << SPR1);
break;
case SPI_SCK_FOSC_128:
SPCR |= ((1 << SPR1) | (1 << SPR0));
break;
case SPI_SCK_FOSC_4: /* fallthrough */
default: break;
}
/* dummy reads before enabling interrupt */
dummy = SPSR;
dummy = SPDR;
(void) dummy; /* suppress warning about unused variable */
SPCR |= (1 << SPIE);
}
#endif /* AVR_SPI_USE_SPI1 */
}
}
/**
* @brief Deactivates the SPI peripheral.
*
* @param[in] spip pointer to the @p SPIDriver object
*
* @notapi
*/
void spi_lld_stop(SPIDriver *spip) {
if (spip->state == SPI_READY) {
/* Resets the peripheral.*/
/* Disables the peripheral.*/
#if AVR_SPI_USE_SPI1
if (&SPID1 == spip) {
SPCR &= ((1 << SPIE) | (1 << SPE));
spip->config->ssport->dir &= ~(1 << spip->config->sspad);
}
/* Disable SPI clock using Power Reduction Register */
#if defined(PRR0)
PRR0 |= (1 << PRSPI);
#elif defined(PRR)
PRR |= (1 << PRSPI);
#endif
#endif /* AVR_SPI_USE_SPI1 */
}
}
/**
* @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) {
/**
* NOTE: This should only be called in master mode
*/
spip->config->ssport->out &= ~(1 << 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) {
/**
* NOTE: This should only be called in master mode
*/
spip->config->ssport->out |= (1 << spip->config->sspad);
}
/**
* @brief Ignores data on the SPI bus.
* @details This asynchronous function starts the transmission of a series of
* idle words on the SPI bus and ignores the received data.
* @post At the end of the operation the configured callback is invoked.
*
* @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->rxbuf = spip->txbuf = NULL;
spip->txbytes = n;
spip->txidx = 0;
SPDR = 0;
}
/**
* @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->rxbuf = rxbuf;
spip->txbuf = txbuf;
spip->txbytes = spip->rxbytes = n;
spip->txidx = spip->rxidx = 0;
SPDR = spip->txbuf[spip->txidx++];
}
/**
* @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->rxbuf = NULL;
spip->txbuf = txbuf;
spip->txbytes = n;
spip->txidx = 0;
SPDR = spip->txbuf[spip->txidx++];
}
/**
* @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->txbuf = NULL;
spip->rxbuf = rxbuf;
spip->rxbytes = n;
spip->rxidx = 0;
/* Write dummy byte to start communication */
SPDR = 0;
}
/**
* @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.
*/
#if AVR_SPI_USE_16BIT_POLLED_EXCHANGE
uint16_t spi_lld_polled_exchange(SPIDriver *spip, uint16_t frame) {
uint16_t spdr = 0;
uint8_t dummy;
/* disable interrupt */
SPCR &= ~(1 << SPIE);
SPDR = frame >> 8;
while (!(SPSR & (1 << SPIF))) ;
spdr = SPDR << 8;
SPDR = frame & 0xFF;
while (!(SPSR & (1 << SPIF))) ;
spdr |= SPDR;
dummy = SPSR;
dummy = SPDR;
(void) dummy; /* suppress warning about unused variable */
SPCR |= (1 << SPIE);
return spdr;
}
#else /* AVR_SPI_USE_16BIT_POLLED_EXCHANGE */
uint8_t spi_lld_polled_exchange(SPIDriver *spip, uint8_t frame) {
uint8_t spdr = 0;
uint8_t dummy;
/* disable interrupt */
SPCR &= ~(1 << SPIE);
SPDR = frame;
while (!(SPSR & (1 << SPIF))) ;
spdr = SPDR;
dummy = SPSR;
dummy = SPDR;
(void) dummy; /* suppress warning about unused variable */
SPCR |= (1 << SPIE);
return spdr;
}
#endif /* AVR_SPI_USE_16BIT_POLLED_EXCHANGE */
#endif /* HAL_USE_SPI */
/** @} */
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