USBMSC.cpp

// Copyright 2015-2021 Espressif Systems (Shanghai) PTE LTD
//
// 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 "USBMSC.h"

#if SOC_USB_OTG_SUPPORTED
#if CONFIG_TINYUSB_MSC_ENABLED

#include "esp32-hal-tinyusb.h"

extern "C" uint16_t tusb_msc_load_descriptor(uint8_t* dst, uint8_t* itf) {
  uint8_t str_index = tinyusb_add_string_descriptor("TinyUSB MSC");
  uint8_t ep_num = tinyusb_get_free_duplex_endpoint();
  TU_VERIFY(ep_num != 0);
  uint8_t descriptor[TUD_MSC_DESC_LEN] = {
    // Interface number, string index, EP Out & EP In address, EP size
    TUD_MSC_DESCRIPTOR(*itf, str_index, ep_num, (uint8_t)(0x80 | ep_num), 64)
  };
  *itf += 1;
  memcpy(dst, descriptor, TUD_MSC_DESC_LEN);
  return TUD_MSC_DESC_LEN;
}

typedef struct {
  bool media_present;
  uint8_t vendor_id[8];
  uint8_t product_id[16];
  uint8_t product_rev[4];
  uint16_t block_size;
  uint32_t block_count;
  bool (*start_stop)(uint8_t power_condition, bool start, bool load_eject);
  int32_t (*read)(uint32_t lba, uint32_t offset, void* buffer, uint32_t bufsize);
  int32_t (*write)(uint32_t lba, uint32_t offset, uint8_t* buffer, uint32_t bufsize);
} msc_lun_t;

static const uint8_t MSC_MAX_LUN = 3;
static uint8_t MSC_ACTIVE_LUN = 0;
static msc_lun_t msc_luns[MSC_MAX_LUN];

static void cplstr(void* dst, const void* src, size_t max_len) {
  if (!src || !dst || !max_len) {
    return;
  }
  size_t l = strlen((const char*)src);
  if (l > max_len) {
    l = max_len;
  }
  memcpy(dst, src, l);
}

// Invoked when received GET_MAX_LUN request, required for multiple LUNs implementation
uint8_t tud_msc_get_maxlun_cb(void) {
  log_v("%u", MSC_ACTIVE_LUN);
  return MSC_ACTIVE_LUN;
}

// 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]) {
  log_v("[%u]", lun);
  cplstr(vendor_id, msc_luns[lun].vendor_id, 8);
  cplstr(product_id, msc_luns[lun].product_id, 16);
  cplstr(product_rev, msc_luns[lun].product_rev, 4);
}

// 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) {
  log_v("[%u]: %u", lun, msc_luns[lun].media_present);
  return msc_luns[lun].media_present;  // RAM disk is always ready
}

// 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) {
  log_v("[%u]", lun);
  if (!msc_luns[lun].media_present) {
    *block_count = 0;
    *block_size = 0;
    return;
  }

  *block_count = msc_luns[lun].block_count;
  *block_size = msc_luns[lun].block_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) {
  log_v("[%u] power: %u, start: %u, eject: %u", lun, power_condition, start, load_eject);
  if (msc_luns[lun].start_stop) {
    return msc_luns[lun].start_stop(power_condition, start, load_eject);
  }
  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) {
  log_v("[%u], lba: %u, offset: %u, bufsize: %u", lun, lba, offset, bufsize);
  if (!msc_luns[lun].media_present) {
    return 0;
  }
  if (msc_luns[lun].read) {
    return msc_luns[lun].read(lba, offset, buffer, bufsize);
  }
  return 0;
}

// Callback invoked when received WRITE10 command.
// Process data in buffer to disk's storage and return number of written bytes
int32_t tud_msc_write10_cb(uint8_t lun, uint32_t lba, uint32_t offset, uint8_t* buffer, uint32_t bufsize) {
  log_v("[%u], lba: %u, offset: %u, bufsize: %u", lun, lba, offset, bufsize);
  if (!msc_luns[lun].media_present) {
    return 0;
  }
  if (msc_luns[lun].write) {
    return msc_luns[lun].write(lba, offset, buffer, bufsize);
  }
  return 0;
}

// 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
  log_v("[%u] cmd: %u, bufsize: %u", lun, scsi_cmd[0], bufsize);

  void const* response = NULL;
  uint16_t resplen = 0;

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

  if (!msc_luns[lun].media_present) {
    return -1;
  }

  switch (scsi_cmd[0]) {
    case SCSI_CMD_PREVENT_ALLOW_MEDIUM_REMOVAL:
      // Host is about to read/write etc ... better not to disconnect disk
      resplen = 0;
      break;

    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, resplen);
    } else {
      // SCSI output
    }
  }

  return resplen;
}

USBMSC::USBMSC() {
  if (MSC_ACTIVE_LUN < MSC_MAX_LUN) {
    _lun = MSC_ACTIVE_LUN;
    MSC_ACTIVE_LUN++;
    msc_luns[_lun].media_present = false;
    msc_luns[_lun].vendor_id[0] = 0;
    msc_luns[_lun].product_id[0] = 0;
    msc_luns[_lun].product_rev[0] = 0;
    msc_luns[_lun].block_size = 0;
    msc_luns[_lun].block_count = 0;
    msc_luns[_lun].start_stop = NULL;
    msc_luns[_lun].read = NULL;
    msc_luns[_lun].write = NULL;
  }
  if (_lun == 0) {
    tinyusb_enable_interface(USB_INTERFACE_MSC, TUD_MSC_DESC_LEN, tusb_msc_load_descriptor);
  }
}

USBMSC::~USBMSC() {
  end();
}

bool USBMSC::begin(uint32_t block_count, uint16_t block_size) {
  msc_luns[_lun].block_size = block_size;
  msc_luns[_lun].block_count = block_count;
  if (!msc_luns[_lun].block_size || !msc_luns[_lun].block_count || !msc_luns[_lun].read || !msc_luns[_lun].write) {
    return false;
  }
  return true;
}

void USBMSC::end() {
  msc_luns[_lun].media_present = false;
  msc_luns[_lun].vendor_id[0] = 0;
  msc_luns[_lun].product_id[0] = 0;
  msc_luns[_lun].product_rev[0] = 0;
  msc_luns[_lun].block_size = 0;
  msc_luns[_lun].block_count = 0;
  msc_luns[_lun].start_stop = NULL;
  msc_luns[_lun].read = NULL;
  msc_luns[_lun].write = NULL;
}

void USBMSC::vendorID(const char* vid) {
  cplstr(msc_luns[_lun].vendor_id, vid, 8);
}

void USBMSC::productID(const char* pid) {
  cplstr(msc_luns[_lun].product_id, pid, 16);
}

void USBMSC::productRevision(const char* rev) {
  cplstr(msc_luns[_lun].product_rev, rev, 4);
}

void USBMSC::onStartStop(msc_start_stop_cb cb) {
  msc_luns[_lun].start_stop = cb;
}

void USBMSC::onRead(msc_read_cb cb) {
  msc_luns[_lun].read = cb;
}

void USBMSC::onWrite(msc_write_cb cb) {
  msc_luns[_lun].write = cb;
}

void USBMSC::mediaPresent(bool media_present) {
  msc_luns[_lun].media_present = media_present;
}

#endif /* CONFIG_TINYUSB_MSC_ENABLED */
#endif /* SOC_USB_OTG_SUPPORTED */