SPI.cpp

/*
 * Copyright (c) 2010 by Cristian Maglie <c.maglie@arduino.cc>
 * 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;
	interruptSave = 0;
	interruptMask[0] = 0;
	interruptMask[1] = 0;
	interruptMask[2] = 0;
	interruptMask[3] = 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, faultmask;
	asm volatile ("mrs %0, primask" : "=r" (primask));
	if (primask) return 0;
	asm volatile ("mrs %0, faultmask" : "=r" (faultmask));
	if (faultmask) return 0;
	return 1;
}
#endif

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

	irestore = interruptsStatus();
	noInterrupts();
	if (interruptMode < 16) {
		if (interruptNumber > NUM_DIGITAL_PINS) {
			interruptMode = 16;
		} else {
			Pio *pio = g_APinDescription[interruptNumber].pPort;
			uint32_t mask = g_APinDescription[interruptNumber].ulPin;
			if (pio == PIOA) {
				interruptMode |= 1;
				interruptMask[0] |= mask;
			} else if (pio == PIOB) {
				interruptMode |= 2;
				interruptMask[1] |= mask;
			} else if (pio == PIOC) {
				interruptMode |= 4;
				interruptMask[2] |= mask;
			} else if (pio == PIOD) {
				interruptMode |= 8;
				interruptMask[3] |= mask;
			} else {
				interruptMode = 16;
			}
		}
	}
	if (irestore) interrupts();
}

void SPIClass::beginTransaction(uint8_t pin, SPISettings settings)
{
	uint8_t mode = interruptMode;
	if (mode > 0) {
		if (mode < 16) {
			if (mode & 1) PIOA->PIO_IDR = interruptMask[0];
			if (mode & 2) PIOB->PIO_IDR = interruptMask[1];
			if (mode & 4) PIOC->PIO_IDR = interruptMask[2];
			if (mode & 8) PIOD->PIO_IDR = interruptMask[3];
		} else {
			interruptSave = interruptsStatus();
			noInterrupts();
		}
	}
	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(pin);
	bitOrder[ch] = settings.border;
	SPI_ConfigureNPCS(spi, ch, settings.config);
	//setBitOrder(pin, settings.border);
	//setDataMode(pin, settings.datamode);
	//setClockDivider(pin, settings.clockdiv);
}

void SPIClass::endTransaction(void)
{
	uint8_t mode = interruptMode;
	if (mode > 0) {
		if (mode < 16) {
			if (mode & 1) PIOA->PIO_IER = interruptMask[0];
			if (mode & 2) PIOB->PIO_IER = interruptMask[1];
			if (mode & 4) PIOC->PIO_IER = interruptMask[2];
			if (mode & 8) PIOD->PIO_IER = interruptMask[3];
		} 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;
}

uint16_t SPIClass::transfer16(byte _pin, uint16_t _data, SPITransferMode _mode) {
	union { uint16_t val; struct { uint8_t lsb; uint8_t msb; }; } t;
	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(_pin);

	t.val = _data;

	if (bitOrder[ch] == LSBFIRST) {
		t.lsb = transfer(_pin, t.lsb, SPI_CONTINUE);
		t.msb = transfer(_pin, t.msb, _mode);
	} else {
		t.msb = transfer(_pin, t.msb, SPI_CONTINUE);
		t.lsb = transfer(_pin, t.lsb, _mode);
	}

	return t.val;
}

void SPIClass::transfer(byte _pin, void *_buf, size_t _count, SPITransferMode _mode) {
	if (_count == 0)
		return;

	uint8_t *buffer = (uint8_t *)_buf;
	if (_count == 1) {
		*buffer = transfer(_pin, *buffer, _mode);
		return;
	}

	uint32_t ch = BOARD_PIN_TO_SPI_CHANNEL(_pin);
	bool reverse = (bitOrder[ch] == LSBFIRST);

	// Send the first byte
	uint32_t d = *buffer;
	if (reverse)
		d = __REV(__RBIT(d));
	while ((spi->SPI_SR & SPI_SR_TDRE) == 0)
		;
	spi->SPI_TDR = d | SPI_PCS(ch);

	while (_count > 1) {
		// Prepare next byte
		d = *(buffer+1);
		if (reverse)
			d = __REV(__RBIT(d));
		if (_count == 2 && _mode == SPI_LAST)
			d |= SPI_TDR_LASTXFER;

		// Read transferred byte and send next one straight away
		while ((spi->SPI_SR & SPI_SR_RDRF) == 0)
			;
		uint8_t r = spi->SPI_RDR;
		spi->SPI_TDR = d | SPI_PCS(ch);

		// Save read byte
		if (reverse)
			r = __REV(__RBIT(r));
		*buffer = r;
		buffer++;
		_count--;
	}

	// Receive the last transferred byte
	while ((spi->SPI_SR & SPI_SR_RDRF) == 0)
		;
	uint8_t r = spi->SPI_RDR;
	if (reverse)
		r = __REV(__RBIT(r));
	*buffer = r;
}

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