spi.c
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/*
* Copyright (C) 2014 Hamburg University of Applied Sciences
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
/**
* @ingroup cpu_sam3x8e
* @{
*
* @file
* @brief Low-level SPI driver implementation
*
* @author Maxime Blanloeil <maxime.blanloeil@phelma.grenoble-inp.fr>
* @author Peter Kietzmann <peter.kietzmann@haw-hamburg.de>
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*
* @}
*/
#include "cpu.h"
#include "mutex.h"
#include "periph/gpio.h"
#include "periph_conf.h"
#include "periph/spi.h"
#include "sam3x8e.h"
/* guard this file in case no SPI device is defined */
#if SPI_NUMOF
/**
* @brief Array holding one pre-initialized mutex for each SPI device
*/
static mutex_t locks[] = {
#if SPI_0_EN
[SPI_0] = MUTEX_INIT,
#endif
#if SPI_1_EN
[SPI_1] = MUTEX_INIT,
#endif
#if SPI_2_EN
[SPI_2] = MUTEX_INIT
#endif
};
typedef struct {
char(*cb)(char data);
} spi_state_t;
static inline void irq_handler_transfer(Spi *spi, spi_t dev);
static spi_state_t spi_config[SPI_NUMOF];
void spi_poweron(spi_t dev)
{
switch (dev) {
#if SPI_0_EN
case SPI_0:
SPI_0_CLKEN();
SPI_0_MISO_PORT_CLKEN();
SPI_0_MOSI_PORT_CLKEN();
SPI_0_SCK_PORT_CLKEN();
break;
#endif /* SPI_0_EN */
}
}
void spi_poweroff(spi_t dev)
{
switch (dev) {
#if SPI_0_EN
case SPI_0:
while (!(SPI_0_DEV->SPI_SR & SPI_SR_SPIENS)) {} /* not busy anymore */
SPI_0_CLKDIS();
NVIC_DisableIRQ(SPI_0_IRQ);
break;
#endif /* SPI_0_EN */
}
}
int spi_init_master(spi_t dev, spi_conf_t conf, spi_speed_t speed)
{
uint8_t speed_divider;
Spi *spi_port;
spi_poweron(dev);
switch (speed) {
case SPI_SPEED_400KHZ:
speed_divider = 210;
break;
case SPI_SPEED_1MHZ:
speed_divider = 84;
break;
case SPI_SPEED_5MHZ:
speed_divider = 17;
break;
case SPI_SPEED_10MHZ: /* this might be too fast */
speed_divider = 8;
break;
default:
return -1;
}
switch (dev) {
#if SPI_0_EN
case SPI_0:
spi_port = SPI_0_DEV;
break;
#endif /* SPI_0_EN */
default:
return -2;
}
/* Configure SCK, MISO and MOSI pin */
spi_conf_pins(dev);
/***************** SPI-Init *****************/
/* Chip Select Register */
spi_port->SPI_CSR[0] = 0; /* This is index 0 since we don't use internal CS-Signals */
switch (conf) {
case SPI_CONF_FIRST_RISING:
spi_port->SPI_CSR[0] &= ~SPI_CSR_CPOL;
spi_port->SPI_CSR[0] |= SPI_CSR_NCPHA;
break;
case SPI_CONF_SECOND_RISING:
spi_port->SPI_CSR[0] &= ~SPI_CSR_CPOL;
spi_port->SPI_CSR[0] &= ~SPI_CSR_NCPHA;
break;
case SPI_CONF_FIRST_FALLING:
spi_port->SPI_CSR[0] |= SPI_CSR_CPOL;
spi_port->SPI_CSR[0] |= SPI_CSR_NCPHA;
break;
case SPI_CONF_SECOND_FALLING:
spi_port->SPI_CSR[0] |= SPI_CSR_CPOL;
spi_port->SPI_CSR[0] &= ~ SPI_CSR_NCPHA;
break;
default:
return -2;
}
spi_port->SPI_CSR[0] |= SPI_CSR_SCBR(speed_divider);
spi_port->SPI_CSR[0] |= SPI_CSR_BITS_8_BIT;
/* Control Register */
spi_port->SPI_CR |= SPI_CR_SPIEN;
/* Mode Register */
spi_port->SPI_MR = 0;
spi_port->SPI_MR |= SPI_MR_MSTR;
spi_port->SPI_MR |= SPI_MR_MODFDIS;
spi_port->SPI_MR &= ~SPI_MR_PS;
spi_port->SPI_MR &= ~SPI_MR_PCS(0);
return 0;
}
int spi_init_slave(spi_t dev, spi_conf_t conf, char(*cb)(char data))
{
Spi *spi_port;
spi_poweron(dev);
switch (dev) {
#if SPI_0_EN
case SPI_0:
spi_port = SPI_0_DEV;
NVIC_SetPriority(SPI_0_IRQ, SPI_0_IRQ_PRIO);
NVIC_EnableIRQ(SPI_0_IRQ);
/* Initialize predefined NSS pin as output so it is "disabled" */
PIOA->PIO_PER |= PIO_PA28A_SPI0_NPCS0;
PIOA->PIO_OER |= PIO_PA28A_SPI0_NPCS0;
break;
#endif /* SPI_0_EN */
default:
return -1;
}
/* Configure SCK, MISO and MOSI pin */
spi_conf_pins(dev);
/***************** SPI-Init *****************/
/* Chip Select Register */
spi_port->SPI_CSR[0] = 0;
switch (conf) {
case SPI_CONF_FIRST_RISING:
spi_port->SPI_CSR[0] &= ~SPI_CSR_CPOL;
spi_port->SPI_CSR[0] |= SPI_CSR_NCPHA;
break;
case SPI_CONF_SECOND_RISING:
spi_port->SPI_CSR[0] &= ~SPI_CSR_CPOL;
spi_port->SPI_CSR[0] &= ~SPI_CSR_NCPHA;
break;
case SPI_CONF_FIRST_FALLING:
spi_port->SPI_CSR[0] |= SPI_CSR_CPOL;
spi_port->SPI_CSR[0] |= SPI_CSR_NCPHA;
break;
case SPI_CONF_SECOND_FALLING:
spi_port->SPI_CSR[0] |= SPI_CSR_CPOL;
spi_port->SPI_CSR[0] &= ~ SPI_CSR_NCPHA;
break;
default:
return -1;
}
/* Control Register */
spi_port->SPI_CR |= SPI_CR_SPIEN;
/* Mode Register */
spi_port->SPI_MR = 0;
spi_port->SPI_MR |= SPI_MR_MODFDIS;
/* Enable SPI interrupts */
spi_port->SPI_IER = 0;
spi_port->SPI_IDR = ~(0);
spi_port->SPI_IER |= 1;
spi_port->SPI_IDR &= ~SPI_IDR_RDRF;
/* Set callback */
spi_config[dev].cb = cb;
return 0;
}
int spi_conf_pins(spi_t dev)
{
switch (dev) {
#if SPI_0_EN
case SPI_0:
/***************** PIO-Init *****************/
/* Push-pull configuration */
SPI_0_MISO_PORT->PIO_MDER &= ~SPI_0_MISO_PIN;
SPI_0_MISO_PORT->PIO_MDDR |= SPI_0_MISO_PIN;
SPI_0_MOSI_PORT->PIO_MDER &= ~SPI_0_MOSI_PIN;
SPI_0_MOSI_PORT->PIO_MDDR |= SPI_0_MOSI_PIN;
SPI_0_SCK_PORT->PIO_MDER &= ~SPI_0_SCK_PIN;
SPI_0_SCK_PORT->PIO_MDDR |= SPI_0_SCK_PIN;
/* With pull-up resistors */
SPI_0_MISO_PORT->PIO_PUDR &= ~SPI_0_MISO_PIN;
SPI_0_MISO_PORT->PIO_PUER |= SPI_0_MISO_PIN;
SPI_0_MOSI_PORT->PIO_PUDR &= ~SPI_0_MOSI_PIN;
SPI_0_MOSI_PORT->PIO_PUER |= SPI_0_MOSI_PIN;
SPI_0_SCK_PORT->PIO_PUDR &= ~SPI_0_SCK_PIN;
SPI_0_SCK_PORT->PIO_PUER |= SPI_0_SCK_PIN;
/* Clear output */
SPI_0_MISO_PORT->PIO_SODR &= ~SPI_0_MISO_PIN;
SPI_0_MISO_PORT->PIO_CODR |= SPI_0_MISO_PIN;
SPI_0_MOSI_PORT->PIO_SODR &= ~SPI_0_MOSI_PIN;
SPI_0_MOSI_PORT->PIO_CODR |= SPI_0_MOSI_PIN;
SPI_0_SCK_PORT->PIO_SODR &= ~SPI_0_SCK_PIN;
SPI_0_SCK_PORT->PIO_CODR |= SPI_0_SCK_PIN;
/* Peripheral Function Selection */
SPI_0_MISO_PORT->PIO_PER &= ~SPI_0_MISO_PIN;
SPI_0_MISO_PORT->PIO_PDR |= SPI_0_MISO_PIN;
SPI_0_MOSI_PORT->PIO_PER &= ~SPI_0_MOSI_PIN;
SPI_0_MOSI_PORT->PIO_PDR |= SPI_0_MOSI_PIN;
SPI_0_SCK_PORT->PIO_PER &= ~SPI_0_SCK_PIN;
SPI_0_SCK_PORT->PIO_PDR |= SPI_0_SCK_PIN;
/* Peripheral A */
SPI_0_MISO_PORT->PIO_ABSR &= ~SPI_0_MISO_PIN;
SPI_0_MOSI_PORT->PIO_ABSR &= ~SPI_0_MOSI_PIN;
SPI_0_SCK_PORT->PIO_ABSR &= ~SPI_0_SCK_PIN;
break;
#endif /* SPI_0_EN */
default:
return -1;
}
return 0;
}
int spi_acquire(spi_t dev)
{
if ((unsigned int)dev >= SPI_NUMOF) {
return -1;
}
mutex_lock(&locks[dev]);
return 0;
}
int spi_release(spi_t dev)
{
if ((unsigned int)dev >= SPI_NUMOF) {
return -1;
}
mutex_unlock(&locks[dev]);
return 0;
}
int spi_transfer_byte(spi_t dev, char out, char *in)
{
Spi *spi_port;
switch (dev) {
#if SPI_0_EN
case SPI_0:
spi_port = SPI_0_DEV;
break;
#endif /* SPI_0_EN */
default:
return -1;
}
while (!(spi_port->SPI_SR & SPI_SR_TDRE)) {}
spi_port->SPI_TDR = SPI_TDR_TD(out);
while (!(spi_port->SPI_SR & SPI_SR_RDRF)) {}
*in = spi_port->SPI_RDR & SPI_RDR_RD_Msk;
return 1;
}
void spi_transmission_begin(spi_t dev, char reset_val)
{
switch (dev) {
#if SPI_0_EN
case SPI_0:
SPI_0_DEV->SPI_TDR = SPI_TDR_TD(reset_val);
break;
#endif /* SPI_0_EN */
}
}
static inline void irq_handler_transfer(Spi *spi, spi_t dev)
{
if (spi->SPI_SR & SPI_SR_RDRF) {
char data;
data = spi->SPI_RDR & SPI_RDR_RD_Msk;
data = spi_config[dev].cb(data);
spi->SPI_TDR = SPI_TDR_TD(data);
}
/* See if a thread with higher priority wants to run now */
cortexm_isr_end();
}
#if SPI_0_EN
void SPI_0_IRQ_HANDLER(void)
{
if (SPI_0_DEV->SPI_SR & SPI_SR_RDRF) {
irq_handler_transfer(SPI_0_DEV, SPI_0);
}
}
#endif
#endif /* SPI_NUMOF */