File content as of revision 13:bd9ff402dd42:

/* mbed Microcontroller Library
 * Copyright (c) 2006-2013 ARM Limited
 *
 * 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.
 */
#include <math.h>

#include "spi_api.h"
#include "cmsis.h"
#include "pinmap.h"
#include "error.h"

static const SWM_Map SWM_SPI_SSEL[] = {
    {4, 16},
    {5, 16},
};

static const SWM_Map SWM_SPI_SCLK[] = {
    {3, 24},
    {4, 24},
};

static const SWM_Map SWM_SPI_MOSI[] = {
    {4, 0},
    {5, 0},
};

static const SWM_Map SWM_SPI_MISO[] = {
    {4, 8},
    {5, 16},
};

// bit flags for used SPIs
static unsigned char spi_used = 0;
static int get_available_spi(void) {
    int i;
    for (i=0; i<2; i++) {
        if ((spi_used & (1 << i)) == 0)
            return i;
    }
    return -1;
}

static inline int ssp_disable(spi_t *obj);
static inline int ssp_enable(spi_t *obj);

void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName sclk, PinName ssel) {
    int spi_n = get_available_spi();
    if (spi_n == -1) {
        error("No available SPI");
    }
    obj->spi_n = spi_n;
    spi_used |= (1 << spi_n);
    
    obj->spi = (spi_n) ? (LPC_SPI_TypeDef *)(LPC_SPI1_BASE) : (LPC_SPI_TypeDef *)(LPC_SPI0_BASE);
    
    const SWM_Map *swm;
    uint32_t regVal;
    
    swm = &SWM_SPI_SCLK[obj->spi_n];
    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
    LPC_SWM->PINASSIGN[swm->n] = regVal |  (sclk   << swm->offset);
    
    swm = &SWM_SPI_MOSI[obj->spi_n];
    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
    LPC_SWM->PINASSIGN[swm->n] = regVal |  (mosi   << swm->offset);
    
    swm = &SWM_SPI_MISO[obj->spi_n];
    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
    LPC_SWM->PINASSIGN[swm->n] = regVal |  (miso   << swm->offset);
    
    swm = &SWM_SPI_SSEL[obj->spi_n];
    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
    LPC_SWM->PINASSIGN[swm->n] = regVal |  (ssel   << swm->offset);
    
    // clear interrupts
    obj->spi->INTENCLR = 0x3f;
    
    // enable power and clocking
    switch (obj->spi_n) {
        case 0:
            LPC_SYSCON->SYSAHBCLKCTRL |= (1<<11);
            LPC_SYSCON->PRESETCTRL &= ~(0x1<<0);
            LPC_SYSCON->PRESETCTRL |= (0x1<<0);
            break;
        case 1:
            LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
            LPC_SYSCON->PRESETCTRL &= ~(0x1<<1);
            LPC_SYSCON->PRESETCTRL |= (0x1<<1);
            break;
    }
    
    // set default format and frequency
    if (ssel == NC) {
        spi_format(obj, 8, 0, 0);  // 8 bits, mode 0, master
    } else {
        spi_format(obj, 8, 0, 1);  // 8 bits, mode 0, slave
    }
    spi_frequency(obj, 1000000);
    
    // enable the ssp channel
    ssp_enable(obj);
}

void spi_free(spi_t *obj) {}

void spi_format(spi_t *obj, int bits, int mode, int slave) {
    ssp_disable(obj);
    
    if (!(bits >= 1 && bits <= 16) || !(mode >= 0 && mode <= 3)) {
        error("SPI format error");
    }
    
    
    int polarity = (mode & 0x2) ? 1 : 0;
    int phase = (mode & 0x1) ? 1 : 0;
    
    // set it up
    int DSS = bits - 1;            // DSS (data select size)
    int SPO = (polarity) ? 1 : 0;  // SPO - clock out polarity
    int SPH = (phase) ? 1 : 0;     // SPH - clock out phase
    
    uint32_t tmp = obj->spi->CFG;
    tmp &= ~((1 << 2) | (1 << 4) | (1 << 5));
    tmp |= (SPH << 4) | (SPO << 5) | ((slave ? 0 : 1) << 2);
    obj->spi->CFG = tmp;
    
    // select frame length
    tmp = obj->spi->TXDATCTL;
    tmp &= ~(0xf << 24);
    tmp |= (DSS << 24);
    obj->spi->TXDATCTL = tmp;
    
    ssp_enable(obj);
}

void spi_frequency(spi_t *obj, int hz) {
    ssp_disable(obj);
    
    uint32_t PCLK = SystemCoreClock;
    
    obj->spi->DIV = PCLK/hz - 1;
    obj->spi->DLY = 0;
    ssp_enable(obj);
}

static inline int ssp_disable(spi_t *obj) {
    return obj->spi->CFG &= ~(1 << 0);
}

static inline int ssp_enable(spi_t *obj) {
    return obj->spi->CFG |= (1 << 0);
}

static inline int ssp_readable(spi_t *obj) {
    return obj->spi->STAT & (1 << 0);
}

static inline int ssp_writeable(spi_t *obj) {
    return obj->spi->STAT & (1 << 1);
}

static inline void ssp_write(spi_t *obj, int value) {
    while (!ssp_writeable(obj));
    // end of transfer
    obj->spi->TXDATCTL |= (1 << 20);
    obj->spi->TXDAT = value;
}

static inline int ssp_read(spi_t *obj) {
    while (!ssp_readable(obj));
    return obj->spi->RXDAT;
}

static inline int ssp_busy(spi_t *obj) {
    // TODO
    return 0;
}

int spi_master_write(spi_t *obj, int value) {
    ssp_write(obj, value);
    return ssp_read(obj);
}

int spi_slave_receive(spi_t *obj) {
    return (ssp_readable(obj) && !ssp_busy(obj)) ? (1) : (0);
};

int spi_slave_read(spi_t *obj) {
    return obj->spi->RXDAT;
}

void spi_slave_write(spi_t *obj, int value) {
    while (ssp_writeable(obj) == 0) ;
    obj->spi->TXDAT = value;
}

int spi_busy(spi_t *obj) {
    return ssp_busy(obj);
}