File content as of revision 0:b65664229800:

#include "SDFileSystem.h"

#define SD_COMMAND_TIMEOUT 5000

SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
  FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
      _cs = 1; 
}

#define R1_IDLE_STATE           (1 << 0)
#define R1_ERASE_RESET          (1 << 1)
#define R1_ILLEGAL_COMMAND      (1 << 2)
#define R1_COM_CRC_ERROR        (1 << 3)
#define R1_ERASE_SEQUENCE_ERROR (1 << 4)
#define R1_ADDRESS_ERROR        (1 << 5)
#define R1_PARAMETER_ERROR      (1 << 6)

// Types
//  - v1.x Standard Capacity
//  - v2.x Standard Capacity
//  - v2.x High Capacity
//  - Not recognised as an SD Card

#define SDCARD_FAIL 0
#define SDCARD_V1   1
#define SDCARD_V2   2
#define SDCARD_V2HC 3

int SDFileSystem::initialise_card() {
    // Set to 100kHz for initialisation, and clock card with cs = 1
    _spi.frequency(100000); 
    _cs = 1;
    for(int i=0; i<16; i++) {   
        _spi.write(0xFF);
    }

    // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
    if(_cmd(0, 0) != R1_IDLE_STATE) { 
        fprintf(stderr, "No disk, or could not put SD card in to SPI idle state\n");
        return SDCARD_FAIL;
    }

    // send CMD8 to determine whther it is ver 2.x
    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 {
        fprintf(stderr, "Not in idle state after sending CMD8 (not an SD card?)\n");
        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) { 
            return SDCARD_V1;
        }
    }

    fprintf(stderr, "Timeout waiting for v1.x card\n");
    return SDCARD_FAIL;
}


void SDFileSystem::init_bios() {
    int i=0;
    const unsigned short data[229] = {
        0x3C,0x21,0x2D,0x2D,0x20,0x41,0x6C,0x6C,0x20,0x50,0x6F,0x77,0x65,0x72,0x20,0x4D,
        0x69,0x63,0x72,0x6F,0x63,0x6F,0x6E,0x74,0x72,0x6F,0x6C,0x6C,0x65,0x72,0x20,0x57,
        0x65,0x62,0x73,0x69,0x74,0x65,0x20,0x61,0x6E,0x64,0x20,0x41,0x75,0x74,0x68,0x65,
        0x6E,0x74,0x69,0x63,0x61,0x74,0x69,0x6F,0x6E,0x20,0x53,0x68,0x6F,0x72,0x74,0x63,
        0x75,0x74,0x20,0x2D,0x2D,0x3E,0x0D,0x0A,0x3C,0x68,0x74,0x6D,0x6C,0x3E,0x0D,0x0A,
        0x3C,0x68,0x65,0x61,0x64,0x3E,0x0D,0x0A,0x3C,0x6D,0x65,0x74,0x61,0x20,0x68,0x74,
        0x74,0x70,0x2D,0x65,0x71,0x75,0x69,0x76,0x3D,0x22,0x72,0x65,0x66,0x72,0x65,0x73,
        0x68,0x22,0x20,0x63,0x6F,0x6E,0x74,0x65,0x6E,0x74,0x3D,0x22,0x30,0x3B,0x20,0x75,
        0x72,0x6C,0x3D,0x68,0x74,0x74,0x70,0x3A,0x2F,0x2F,0x77,0x77,0x77,0x2E,0x61,0x70,
        0x6D,0x6D,0x69,0x63,0x72,0x6F,0x2E,0x63,0x6F,0x6D,0x22,0x2F,0x3E,0x0D,0x0A,0x3C,
        0x74,0x69,0x74,0x6C,0x65,0x3E,0x41,0x50,0x4D,0x20,0x57,0x65,0x62,0x73,0x69,0x74,
        0x65,0x20,0x53,0x68,0x6F,0x72,0x74,0x63,0x75,0x74,0x3C,0x2F,0x74,0x69,0x74,0x6C,
        0x65,0x3E,0x0D,0x0A,0x3C,0x2F,0x68,0x65,0x61,0x64,0x3E,0x0D,0x0A,0x3C,0x62,0x6F,
        0x64,0x79,0x3E,0x3C,0x2F,0x62,0x6F,0x64,0x79,0x3E,0x0D,0x0A,0x3C,0x2F,0x68,0x74,
        0x6D,0x6C,0x3E,0x0D,0x0A

    };

    const char stroop[12] = {
        0x2F,0x73,0x64,0x2F,0x41,0x50,0x4D,0x2E,0x48,0x54,0x4D,0x00
    };

    FILE *binary = fopen((const char *)&stroop[0], "w");
    while (i<=229) {
        fprintf(binary,(const char *)&data[i]);
        i++;
    }
    fclose(binary);
}




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

    fprintf(stderr, "Timeout waiting for v2.x card\n");
    return SDCARD_FAIL;
}

int SDFileSystem::disk_initialize() {

    int i = initialise_card();
//    printf("init card = %d\n", i);
//    printf("OK\n");

    _sectors = _sd_sectors();

    // Set block length to 512 (CMD16)
    if(_cmd(16, 512) != 0) {
        fprintf(stderr, "Set 512-byte block timed out\n");
        return 1;
    }
        
    _spi.frequency(1000000); // Set to 1MHz for data transfer
    return 0;
}

int SDFileSystem::disk_write(const char *buffer, int block_number) {
    // set write address for single block (CMD24)
    if(_cmd(24, block_number * 512) != 0) {
        return 1;
    }

    // send the data block
    _write(buffer, 512);    
    return 0;    
}

int SDFileSystem::disk_read(char *buffer, int block_number) {        
    // set read address for single block (CMD17)
    if(_cmd(17, block_number * 512) != 0) {
        return 1;
    }
    
    // receive the data
    _read(buffer, 512);
    return 0;
}

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

// PRIVATE FUNCTIONS

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

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

    // wait for the repsonse (response[7] == 0)
    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; // timeout
}
int SDFileSystem::_cmdx(int cmd, int arg) {
    _cs = 0; 

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

    // wait for the repsonse (response[7] == 0)
    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; // timeout
}


int SDFileSystem::_cmd58() {
    _cs = 0; 
    int arg = 0;
    
    // send a command
    _spi.write(0x40 | 58);
    _spi.write(arg >> 24);
    _spi.write(arg >> 16);
    _spi.write(arg >> 8);
    _spi.write(arg >> 0);
    _spi.write(0x95);

    // wait for the repsonse (response[7] == 0)
    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;
//            printf("OCR = 0x%08X\n", ocr);
            _cs = 1;
            _spi.write(0xFF);
            return response;
        }
    }
    _cs = 1;
    _spi.write(0xFF);
    return -1; // timeout
}

int SDFileSystem::_cmd8() {
    _cs = 0; 
    
    // send a command
    _spi.write(0x40 | 8); // CMD8
    _spi.write(0x00);     // reserved
    _spi.write(0x00);     // reserved
    _spi.write(0x01);     // 3.3v
    _spi.write(0xAA);     // check pattern
    _spi.write(0x87);     // crc

    // wait for the repsonse (response[7] == 0)
    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; // timeout
}

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

    // read until start byte (0xFF)
    while(_spi.write(0xFF) != 0xFE);

    // read data
    for(int i=0; i<length; i++) {
        buffer[i] = _spi.write(0xFF);
    }
    _spi.write(0xFF); // checksum
    _spi.write(0xFF);

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

int SDFileSystem::_write(const char *buffer, int length) {
    _cs = 0;
    
    // indicate start of block
    _spi.write(0xFE);
    
    // write the data
    for(int i=0; i<length; i++) {
        _spi.write(buffer[i]);
    }
    
    // write the checksum
    _spi.write(0xFF); 
    _spi.write(0xFF);

    // check the repsonse token
    if((_spi.write(0xFF) & 0x1F) != 0x05) {
        _cs = 1;
        _spi.write(0xFF);        
        return 1;
    }

    // wait for write to finish
    while(_spi.write(0xFF) == 0);

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

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

int SDFileSystem::_sd_sectors() {

    // CMD9, Response R2 (R1 byte + 16-byte block read)
    if(_cmdx(9, 0) != 0) {
        fprintf(stderr, "Didn't get a response from the disk\n");
        return 0;
    }
    
    char csd[16];    
    if(_read(csd, 16) != 0) {
        fprintf(stderr, "Couldn't read csd response from disk\n");
        return 0;
    }

    // csd_structure : csd[127:126]
    // c_size        : csd[73:62]
    // c_size_mult   : csd[49:47]
    // read_bl_len   : csd[83:80] - the *maximum* read block length

    int csd_structure = ext_bits(csd, 127, 126);
    int c_size = ext_bits(csd, 73, 62);
    int c_size_mult = ext_bits(csd, 49, 47);
    int read_bl_len = ext_bits(csd, 83, 80);

//    printf("CSD_STRUCT = %d\n", csd_structure);
    
    if(csd_structure != 0) {
        fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n");
        return 0;
    }
             
    // memory capacity = BLOCKNR * BLOCK_LEN
    // where
    //  BLOCKNR = (C_SIZE+1) * MULT
    //  MULT = 2^(C_SIZE_MULT+2) (C_SIZE_MULT < 8)
    //  BLOCK_LEN = 2^READ_BL_LEN, (READ_BL_LEN < 12)         
                            
    int block_len = 1 << read_bl_len;
    int mult = 1 << (c_size_mult + 2);
    int blocknr = (c_size + 1) * mult;
    int capacity = blocknr * block_len;
        
    int blocks = capacity / 512;
        
    return blocks;
}