Arduino/hardware/arduino/sam/libraries/SPI/SPI.cpp

/*
 * Copyright (c) 2010 by Cristian Maglie <c.maglie@bug.st>
 * Copyright (c) 2014 by Paul Stoffregen <paul@pjrc.com> (Transaction API)
 * SPI Master library for arduino.
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of either the GNU General Public License version 2
 * or the GNU Lesser General Public License version 2.1, both as
 * published by the Free Software Foundation.
 */

#include "SPI.h"

SPIClass::SPIClass(Spi *_spi, uint32_t _id, void(*_initCb)(void)) :
	spi(_spi), id(_id), initCb(_initCb), initialized(false)
{
	// Empty
}

void SPIClass::begin() {
	init();
	// NPCS control is left to the user

	// Default speed set to 4Mhz
	setClockDivider(BOARD_SPI_DEFAULT_SS, 21);
	setDataMode(BOARD_SPI_DEFAULT_SS, SPI_MODE0);
	setBitOrder(BOARD_SPI_DEFAULT_SS, MSBFIRST);
}

void SPIClass::begin(uint8_t _pin) {
	init();

	uint32_t spiPin = BOARD_PIN_TO_SPI_PIN(_pin);
	PIO_Configure(
		g_APinDescription[spiPin].pPort,
		g_APinDescription[spiPin].ulPinType,
		g_APinDescription[spiPin].ulPin,
		g_APinDescription[spiPin].ulPinConfiguration);

	// Default speed set to 4Mhz
	setClockDivider(_pin, 21);
	setDataMode(_pin, SPI_MODE0);
	setBitOrder(_pin, MSBFIRST);
}

void SPIClass::init() {
	if (initialized)
		return;
	interruptMode = 0;
	interruptMask = 0;
	interruptSave = 0;
	initCb();
	SPI_Configure(spi, id, SPI_MR_MSTR | SPI_MR_PS | SPI_MR_MODFDIS);
	SPI_Enable(spi);
	initialized = true;
}

#ifndef interruptsStatus
#define interruptsStatus() __interruptsStatus()
static inline unsigned char __interruptsStatus(void) __attribute__((always_inline, unused));
static inline unsigned char __interruptsStatus(void) {
  unsigned int primask;
  asm volatile ("mrs %0, primask" : "=r" (primask));
  if (primask) return 0;
  return 1;
}
#endif

void SPIClass::usingInterrupt(uint8_t interruptNumber)
{
	uint8_t irestore;

	irestore = interruptsStatus();
	noInterrupts();
	if (interruptMode < 2) {
		if (interruptNumber > NUM_DIGITAL_PINS) {
			interruptMode = 2;
		} else {
			uint8_t imask = interruptMask;
			Pio *pio = g_APinDescription[interruptNumber].pPort;
			if (pio == PIOA) {
				imask |= 1;
			} else if (pio == PIOB) {
				imask |= 2;
			} else if (pio == PIOC) {
				imask |= 4;
			} else if (pio == PIOD) {
				imask |= 8;
			}
			interruptMask = imask;
			interruptMode = 1;
		}
	}
	if (irestore) interrupts();
}

void SPIClass::beginTransaction(uint8_t pin, SPISettings settings)
{
	if (interruptMode > 0) {
		if (interruptMode == 1) {
			uint8_t imask = interruptMask;
			if (imask & 1) NVIC_DisableIRQ(PIOA_IRQn);
			if (imask & 2) NVIC_DisableIRQ(PIOB_IRQn);
			if (imask & 4) NVIC_DisableIRQ(PIOC_IRQn);
			if (imask & 8) NVIC_DisableIRQ(PIOD_IRQn);
		} else {
			interruptSave = interruptsStatus();
			noInterrupts();
		}
	}
	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(pin);
	bitOrder[ch] = settings.border;
	SPI_ConfigureNPCS(spi, ch, settings.config);
}

void SPIClass::endTransaction(void)
{
	if (interruptMode > 0) {
		if (interruptMode == 1) {
			uint8_t imask = interruptMask;
			if (imask & 1) NVIC_EnableIRQ(PIOA_IRQn);
			if (imask & 2) NVIC_EnableIRQ(PIOB_IRQn);
			if (imask & 4) NVIC_EnableIRQ(PIOC_IRQn);
			if (imask & 8) NVIC_EnableIRQ(PIOD_IRQn);
		} else {
			if (interruptSave) interrupts();
		}
	}
}

void SPIClass::end(uint8_t _pin) {
	uint32_t spiPin = BOARD_PIN_TO_SPI_PIN(_pin);
	// Setting the pin as INPUT will disconnect it from SPI peripheral
	pinMode(spiPin, INPUT);
}

void SPIClass::end() {
	SPI_Disable(spi);
	initialized = false;
}

void SPIClass::setBitOrder(uint8_t _pin, BitOrder _bitOrder) {
	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(_pin);
	bitOrder[ch] = _bitOrder;
}

void SPIClass::setDataMode(uint8_t _pin, uint8_t _mode) {
	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(_pin);
	mode[ch] = _mode | SPI_CSR_CSAAT;
	// SPI_CSR_DLYBCT(1) keeps CS enabled for 32 MCLK after a completed
	// transfer. Some device needs that for working properly.
	SPI_ConfigureNPCS(spi, ch, mode[ch] | SPI_CSR_SCBR(divider[ch]) | SPI_CSR_DLYBCT(1));
}

void SPIClass::setClockDivider(uint8_t _pin, uint8_t _divider) {
	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(_pin);
	divider[ch] = _divider;
	// SPI_CSR_DLYBCT(1) keeps CS enabled for 32 MCLK after a completed
	// transfer. Some device needs that for working properly.
	SPI_ConfigureNPCS(spi, ch, mode[ch] | SPI_CSR_SCBR(divider[ch]) | SPI_CSR_DLYBCT(1));
}

byte SPIClass::transfer(byte _pin, uint8_t _data, SPITransferMode _mode) {
	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(_pin);
	// Reverse bit order
	if (bitOrder[ch] == LSBFIRST)
		_data = __REV(__RBIT(_data));
	uint32_t d = _data | SPI_PCS(ch);
	if (_mode == SPI_LAST)
		d |= SPI_TDR_LASTXFER;

	// SPI_Write(spi, _channel, _data);
    while ((spi->SPI_SR & SPI_SR_TDRE) == 0)
	;
    spi->SPI_TDR = d;

    // return SPI_Read(spi);
    while ((spi->SPI_SR & SPI_SR_RDRF) == 0)
	;
    d = spi->SPI_RDR;
	// Reverse bit order
	if (bitOrder[ch] == LSBFIRST)
		d = __REV(__RBIT(d));
    return d & 0xFF;
}

void SPIClass::attachInterrupt(void) {
	// Should be enableInterrupt()
}

void SPIClass::detachInterrupt(void) {
	// Should be disableInterrupt()
}

#if SPI_INTERFACES_COUNT > 0
static void SPI_0_Init(void) {
	PIO_Configure(
			g_APinDescription[PIN_SPI_MOSI].pPort,
			g_APinDescription[PIN_SPI_MOSI].ulPinType,
			g_APinDescription[PIN_SPI_MOSI].ulPin,
			g_APinDescription[PIN_SPI_MOSI].ulPinConfiguration);
	PIO_Configure(
			g_APinDescription[PIN_SPI_MISO].pPort,
			g_APinDescription[PIN_SPI_MISO].ulPinType,
			g_APinDescription[PIN_SPI_MISO].ulPin,
			g_APinDescription[PIN_SPI_MISO].ulPinConfiguration);
	PIO_Configure(
			g_APinDescription[PIN_SPI_SCK].pPort,
			g_APinDescription[PIN_SPI_SCK].ulPinType,
			g_APinDescription[PIN_SPI_SCK].ulPin,
			g_APinDescription[PIN_SPI_SCK].ulPinConfiguration);
}

SPIClass SPI(SPI_INTERFACE, SPI_INTERFACE_ID, SPI_0_Init);
#endif