lowlevel.c

/**
 * NXT bootstrap interface; low-level USB functions.
 *
 * Copyright 2006 David Anderson <dave@natulte.net>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */

#include <assert.h>
#include <libusb.h>
#include <stdlib.h>
#include <string.h>

#include "lowlevel.h"

const struct
{
  int vendor_id;
  int product_id;
  int interface;
} nxt_usb_ids[N_FIRMWARES] = {
  { 0x03EB, 0x6124, 1 }, /* SAM-BA */
  { 0x0694, 0x0002, 0 }, /* LEGO   */
  { 0x0694, 0xFF00, 0 }  /* NXTOS  */
};

struct nxt_t
{
  libusb_context *usb;
  libusb_device *dev;
  nxt_firmware firmware;
  int interface;
  libusb_device_handle *hdl;
};

nxt_error_t
nxt_init(nxt_t **nxt)
{
  int ret;
  nxt_t *lnxt;

  lnxt = calloc(1, sizeof(*lnxt));
  if (!lnxt)
    return NXT_ERROR_NO_MEM;

  ret = libusb_init(&lnxt->usb);
  if (ret < 0)
    {
      free(lnxt);
      return NXT_ERROR_USB(ret);
    }

  *nxt = lnxt;
  return NXT_OK;
}

nxt_error_t
nxt_find(nxt_t *nxt)
{
  libusb_device **list;

  assert(!nxt->dev);

  ssize_t cnt = libusb_get_device_list(nxt->usb, &list);
  if (cnt < 0)
    {
      return NXT_ERROR_USB(cnt);
    }
  for (ssize_t j = 0; j < cnt; j++)
    {
      libusb_device *dev = list[j];
      struct libusb_device_descriptor desc;
      int ret = libusb_get_device_descriptor(dev, &desc);
      if (ret == 0)
        {
          for (int i = 0; i < N_FIRMWARES; i++)
            {
              if (desc.idVendor == nxt_usb_ids[i].vendor_id &&
                  desc.idProduct == nxt_usb_ids[i].product_id)
                {
                  libusb_ref_device(dev);
                  libusb_free_device_list(list, 1);
                  nxt->dev = dev;
                  nxt->firmware = i;
                  nxt->interface = nxt_usb_ids[i].interface;
                  return NXT_OK;
                }
            }
        }
    }

  libusb_free_device_list(list, 1);
  return NXT_NOT_PRESENT;
}

nxt_error_t
nxt_open(nxt_t *nxt)
{
  int ret;
  libusb_device_handle *hdl;

  assert(nxt->dev);
  assert(!nxt->hdl);

  ret = libusb_open(nxt->dev, &hdl);
  if (ret < 0)
    return NXT_ERROR_USB(ret);

  // Try to detach driver, but ignore errors when not implemented, or kernel
  // driver not attached.
  ret = libusb_detach_kernel_driver(hdl, nxt->interface);
  if (ret < 0 && ret != LIBUSB_ERROR_NOT_SUPPORTED &&
      ret != LIBUSB_ERROR_NOT_FOUND)
    {
      libusb_close(hdl);
      return NXT_ERROR_USB(ret);
    }

  ret = libusb_set_configuration(hdl, 1);
  if (ret < 0 && ret != LIBUSB_ERROR_NOT_SUPPORTED)
    {
      libusb_close(hdl);
      return NXT_ERROR_USB(ret);
    }

  ret = libusb_claim_interface(hdl, nxt->interface);
  if (ret < 0)
    {
      libusb_close(hdl);
      return NXT_ERROR_USB(ret);
    }

  nxt->hdl = hdl;
  return NXT_OK;
}

void
nxt_close(nxt_t *nxt)
{
  if (nxt->hdl)
    {
      libusb_release_interface(nxt->hdl, nxt->interface);
      libusb_close(nxt->hdl);
    }
  if (nxt->dev)
    libusb_unref_device(nxt->dev);
  libusb_exit(nxt->usb);
  free(nxt);
}

int
nxt_is_firmware(nxt_t *nxt, nxt_firmware fw)
{
  return (nxt->firmware == fw);
}

static nxt_error_t
nxt_transfer_buf(nxt_t *nxt, uint8_t endpoint, uint8_t *buf, int len)
{
  int ret;
  int transfered;

  do
    {
      ret = libusb_bulk_transfer(nxt->hdl, endpoint, buf, len, &transfered, 0);
      if (ret < 0)
        return NXT_ERROR_USB(ret);
      buf += transfered;
      len -= transfered;
    }
  while (len);

  return NXT_OK;
}

nxt_error_t
nxt_send_buf(nxt_t *nxt, const uint8_t *buf, int len)
{
  return nxt_transfer_buf(nxt, 0x01, (uint8_t *)buf, len);
}

nxt_error_t
nxt_send_str(nxt_t *nxt, const char *str)
{
  return nxt_send_buf(nxt, (const uint8_t *)str, strlen(str));
}

nxt_error_t
nxt_recv_buf(nxt_t *nxt, uint8_t *buf, int len)
{
  return nxt_transfer_buf(nxt, 0x82, buf, len);
}