SDFileSystem.cpp

#include "SDFileSystem.h"

#define SD_COMMAND_TIMEOUT 5000

#define SD_DBG 0

SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char *name) : FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs), _is_initialized(0)
{
    _cs = 1;
    _init_sck = 100000;
    _transfer_sck = 1000000;
}

#define R1_IDLE_STATE (1 << 0)
#define R1_ILLEGAL_COMMAND (1 << 2)

#define SDCARD_FAIL 0
#define SDCARD_V1 1
#define SDCARD_V2 2

int SDFileSystem::initialise_card()
{

    _spi.frequency(_init_sck);
    _cs = 1;
    for (int i = 0; i < 16; i++)
    {
        _spi.write(0xFF);
    }

    if (_cmd(0, 0) != R1_IDLE_STATE)
    {
        return SDCARD_FAIL;
    }

    int r = _cmd8();
    if (r == R1_IDLE_STATE)
    {
        return initialise_card_v2();
    }
    else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND))
    {
        return initialise_card_v1();
    }
    else
    {
        return SDCARD_FAIL;
    }
}

int SDFileSystem::initialise_card_v1()
{
    for (int i = 0; i < SD_COMMAND_TIMEOUT; i++)
    {
        _cmd(55, 0);
        if (_cmd(41, 0) == 0)
        {
            cdv = 512;
            return SDCARD_V1;
        }
    }

    return SDCARD_FAIL;
}

int SDFileSystem::initialise_card_v2()
{
    for (int i = 0; i < SD_COMMAND_TIMEOUT; i++)
    {
        wait_ms(50);
        _cmd58();
        _cmd(55, 0);
        if (_cmd(41, 0x40000000) == 0)
        {
            _cmd58();
            cdv = 1;
            return SDCARD_V2;
        }
    }
    return SDCARD_FAIL;
}

int SDFileSystem::disk_initialize()
{
    _is_initialized = initialise_card();
    if (_is_initialized == 0)
    {
        return 1;
    }
    _sectors = _sd_sectors();

    if (_cmd(16, 512) != 0)
    {
        return 1;
    }

    _spi.frequency(_transfer_sck);
    return 0;
}

int SDFileSystem::disk_write(const uint8_t *buffer, uint32_t block_number, uint32_t count)
{
    if (!_is_initialized)
    {
        return -1;
    }

    for (uint32_t b = block_number; b < block_number + count; b++)
    {

        if (_cmd(24, b * cdv) != 0)
        {
            return 1;
        }

        _write(buffer, 512);
        buffer += 512;
    }

    return 0;
}

int SDFileSystem::disk_read(uint8_t *buffer, uint32_t block_number, uint32_t count)
{
    if (!_is_initialized)
    {
        return -1;
    }

    for (uint32_t b = block_number; b < block_number + count; b++)
    {

        if (_cmd(17, b * cdv) != 0)
        {
            return 1;
        }

        _read(buffer, 512);
        buffer += 512;
    }

    return 0;
}

int SDFileSystem::disk_status()
{

    if (_is_initialized)
    {
        return 0;
    }
    else
    {
        return 1;
    }
}

int SDFileSystem::disk_sync() { return 0; }
uint32_t SDFileSystem::disk_sectors() { return _sectors; }

int SDFileSystem::_cmd(int cmd, int arg)
{
    _cs = 0;

    _spi.write(0x40 | cmd);
    _spi.write(arg >> 24);
    _spi.write(arg >> 16);
    _spi.write(arg >> 8);
    _spi.write(arg >> 0);
    _spi.write(0x95);

    for (int i = 0; i < SD_COMMAND_TIMEOUT; i++)
    {
        int response = _spi.write(0xFF);
        if (!(response & 0x80))
        {
            _cs = 1;
            _spi.write(0xFF);
            return response;
        }
    }
    _cs = 1;
    _spi.write(0xFF);
    return -1;
}
int SDFileSystem::_cmdx(int cmd, int arg)
{
    _cs = 0;

    _spi.write(0x40 | cmd);
    _spi.write(arg >> 24);
    _spi.write(arg >> 16);
    _spi.write(arg >> 8);
    _spi.write(arg >> 0);
    _spi.write(0x95);

    for (int i = 0; i < SD_COMMAND_TIMEOUT; i++)
    {
        int response = _spi.write(0xFF);
        if (!(response & 0x80))
        {
            return response;
        }
    }
    _cs = 1;
    _spi.write(0xFF);
    return -1;
}

int SDFileSystem::_cmd58()
{
    _cs = 0;
    int arg = 0;

    _spi.write(0x40 | 58);
    _spi.write(arg >> 24);
    _spi.write(arg >> 16);
    _spi.write(arg >> 8);
    _spi.write(arg >> 0);
    _spi.write(0x95);

    for (int i = 0; i < SD_COMMAND_TIMEOUT; i++)
    {
        int response = _spi.write(0xFF);
        if (!(response & 0x80))
        {
            int ocr = _spi.write(0xFF) << 24;
            ocr |= _spi.write(0xFF) << 16;
            ocr |= _spi.write(0xFF) << 8;
            ocr |= _spi.write(0xFF) << 0;
            _cs = 1;
            _spi.write(0xFF);
            return response;
        }
    }
    _cs = 1;
    _spi.write(0xFF);
    return -1;
}

int SDFileSystem::_cmd8()
{
    _cs = 0;

    _spi.write(0x40 | 8);
    _spi.write(0x00);
    _spi.write(0x00);
    _spi.write(0x01);
    _spi.write(0xAA);
    _spi.write(0x87);

    for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++)
    {
        char response[5];
        response[0] = _spi.write(0xFF);
        if (!(response[0] & 0x80))
        {
            for (int j = 1; j < 5; j++)
            {
                response[i] = _spi.write(0xFF);
            }
            _cs = 1;
            _spi.write(0xFF);
            return response[0];
        }
    }
    _cs = 1;
    _spi.write(0xFF);
    return -1;
}

int SDFileSystem::_read(uint8_t *buffer, uint32_t length)
{
    _cs = 0;

    while (_spi.write(0xFF) != 0xFE)
        ;

    for (uint32_t i = 0; i < length; i++)
    {
        buffer[i] = _spi.write(0xFF);
    }
    _spi.write(0xFF);
    _spi.write(0xFF);

    _cs = 1;
    _spi.write(0xFF);
    return 0;
}

int SDFileSystem::_write(const uint8_t *buffer, uint32_t length)
{
    _cs = 0;

    _spi.write(0xFE);

    for (uint32_t i = 0; i < length; i++)
    {
        _spi.write(buffer[i]);
    }

    _spi.write(0xFF);
    _spi.write(0xFF);

    if ((_spi.write(0xFF) & 0x1F) != 0x05)
    {
        _cs = 1;
        _spi.write(0xFF);
        return 1;
    }

    while (_spi.write(0xFF) == 0)
        ;

    _cs = 1;
    _spi.write(0xFF);
    return 0;
}

static uint32_t ext_bits(unsigned char *data, int msb, int lsb)
{
    uint32_t bits = 0;
    uint32_t size = 1 + msb - lsb;
    for (uint32_t i = 0; i < size; i++)
    {
        uint32_t position = lsb + i;
        uint32_t byte = 15 - (position >> 3);
        uint32_t bit = position & 0x7;
        uint32_t value = (data[byte] >> bit) & 1;
        bits |= value << i;
    }
    return bits;
}

uint32_t SDFileSystem::_sd_sectors()
{
    uint32_t c_size, c_size_mult, read_bl_len;
    uint32_t block_len, mult, blocknr, capacity;
    uint32_t hc_c_size;
    uint32_t blocks;

    if (_cmdx(9, 0) != 0)
    {
        return 0;
    }

    uint8_t csd[16];
    if (_read(csd, 16) != 0)
    {
        return 0;
    }

    int csd_structure = ext_bits(csd, 127, 126);

    switch (csd_structure)
    {
    case 0:
        cdv = 512;
        c_size = ext_bits(csd, 73, 62);
        c_size_mult = ext_bits(csd, 49, 47);
        read_bl_len = ext_bits(csd, 83, 80);

        block_len = 1 << read_bl_len;
        mult = 1 << (c_size_mult + 2);
        blocknr = (c_size + 1) * mult;
        capacity = blocknr * block_len;
        blocks = capacity / 512;
        break;

    case 1:
        cdv = 1;
        hc_c_size = ext_bits(csd, 63, 48);
        blocks = (hc_c_size + 1) * 1024;
        break;

    default:
        return 0;
    };
    return blocks;
}