PicoPAC/VSC-PicoPAC/msc_disk.c

/*
//                       PicoPAC MultiCART by Andrea Ottaviani 2024
//
//  VIDEOPAC  multicart based on Raspberry Pico board -
//
//  More info on https://github.com/aotta/ 
//
//   parts of code are directly from the A8PicoCart project by Robin Edwards 2023
//  
//   Needs to be a release NOT debug build for the cartridge emulation to work
// 
//   Edit myboard.h depending on the type of flash memory on the pico clone//
//
//   v. 1.0 2024-08-05 : Initial version for Pi Pico 
//
*/



#include "tusb.h"
#include "fatfs_disk.h"

// whether host does safe-eject
static bool ejected = false;


// Invoked when received SCSI_CMD_INQUIRY
// Application fill vendor id, product id and revision with string up to 8, 16, 4 characters respectively
void tud_msc_inquiry_cb(uint8_t lun, uint8_t vendor_id[8], uint8_t product_id[16], uint8_t product_rev[4])
{
  (void) lun;

  const char vid[] = "PicoCart";
  const char pid[] = "Mass Storage";
  const char rev[] = "1.0";

  memcpy(vendor_id  , vid, strlen(vid));
  memcpy(product_id , pid, strlen(pid));
  memcpy(product_rev, rev, strlen(rev));
}

// Invoked when received Test Unit Ready command.
// return true allowing host to read/write this LUN e.g SD card inserted
bool tud_msc_test_unit_ready_cb(uint8_t lun)
{
  (void) lun;

  // RAM disk is ready until ejected
  if (ejected) {
    // Additional Sense 3A-00 is NOT_FOUND
    tud_msc_set_sense(lun, SCSI_SENSE_NOT_READY, 0x3a, 0x00);
    return false;
  }

  return true;
}

// Invoked when received SCSI_CMD_READ_CAPACITY_10 and SCSI_CMD_READ_FORMAT_CAPACITY to determine the disk size
// Application update block count and block size
void tud_msc_capacity_cb(uint8_t lun, uint32_t* block_count, uint16_t* block_size)
{
  (void) lun;

  *block_count = SECTOR_NUM;
  *block_size  = SECTOR_SIZE;
}

// Invoked when received Start Stop Unit command
// - Start = 0 : stopped power mode, if load_eject = 1 : unload disk storage
// - Start = 1 : active mode, if load_eject = 1 : load disk storage
bool tud_msc_start_stop_cb(uint8_t lun, uint8_t power_condition, bool start, bool load_eject)
{
  (void) lun;
  (void) power_condition;

  if ( load_eject )
  {
    if (start)
    {
      // load disk storage
    }else
    {
      // unload disk storage
      ejected = true;
    }
  }

  return true;
}

// Callback invoked when received READ10 command.
// Copy disk's data to buffer (up to bufsize) and return number of copied bytes.
int32_t tud_msc_read10_cb(uint8_t lun, uint32_t lba, uint32_t offset, void* buffer, uint32_t bufsize)
{
  (void) lun;

  if(offset != 0) return -1;	
  if(bufsize != SECTOR_SIZE) return -1;	

  uint32_t status = fatfs_disk_read(buffer, lba, 1);
  if(status != 0) return -1;
  return (int32_t) bufsize;
}

bool tud_msc_is_writable_cb (uint8_t lun)
{
  (void) lun;
  return true;
}

// Callback invoked when received WRITE10 command.
// Process data in buffer to disk's storage and return number of written bytes
alarm_id_t alarm_id = -1;
int64_t sync_callback(alarm_id_t id, void *user_data)
{
   	fatfs_disk_sync();
}

int32_t tud_msc_write10_cb(uint8_t lun, uint32_t lba, uint32_t offset, uint8_t* buffer, uint32_t bufsize)
{
  (void) lun;

  if(offset != 0) return -1;	
  if(bufsize != SECTOR_SIZE) return -1;	

  uint32_t status = fatfs_disk_write(buffer, lba, 1);

  // we need to sync the flash but only do it when activity dies down :-)
  if(alarm_id >= 0)
      cancel_alarm(alarm_id);
  alarm_id = add_alarm_in_ms(250, sync_callback, NULL, false);

  if(status != 0) return -1;
  return (int32_t) bufsize;
}

// Callback invoked when received an SCSI command not in built-in list below
// - READ_CAPACITY10, READ_FORMAT_CAPACITY, INQUIRY, MODE_SENSE6, REQUEST_SENSE
// - READ10 and WRITE10 has their own callbacks
int32_t tud_msc_scsi_cb (uint8_t lun, uint8_t const scsi_cmd[16], void* buffer, uint16_t bufsize)
{
  // read10 & write10 has their own callback and MUST not be handled here

  void const* response = NULL;
  int32_t resplen = 0;

  // most scsi handled is input
  bool in_xfer = true;

  switch (scsi_cmd[0])
  {
    default:
      // Set Sense = Invalid Command Operation
      tud_msc_set_sense(lun, SCSI_SENSE_ILLEGAL_REQUEST, 0x20, 0x00);

      // negative means error -> tinyusb could stall and/or response with failed status
      resplen = -1;
    break;
  }

  // return resplen must not larger than bufsize
  if ( resplen > bufsize ) resplen = bufsize;

  if ( response && (resplen > 0) )
  {
    if(in_xfer)
    {
      memcpy(buffer, response, (size_t) resplen);
    }else
    {
      // SCSI output
    }
  }

  return (int32_t) resplen;
}