/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT 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 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT 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, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    STM32/USBv1/usb_lld.c
 * @brief   STM32 USB subsystem low level driver source.
 *
 * @addtogroup USB
 * @{
 */

#include <string.h>

#include "ch.h"
#include "hal.h"

#if HAL_USE_USB || defined(__DOXYGEN__)

#define BTABLE_ADDR     0x0000

/*===========================================================================*/
/* Driver exported variables.                                                */
/*===========================================================================*/

/** @brief USB1 driver identifier.*/
#if STM32_USB_USE_USB1 || defined(__DOXYGEN__)
USBDriver USBD1;
#endif

/*===========================================================================*/
/* Driver local variables.                                                   */
/*===========================================================================*/

/**
 * @brief   EP0 state.
 * @note    It is an union because IN and OUT endpoints are never used at the
 *          same time for EP0.
 */
static union {
  /**
   * @brief   IN EP0 state.
   */
  USBInEndpointState in;
  /**
   * @brief   OUT EP0 state.
   */
  USBOutEndpointState out;
} ep0_state;

/**
 * @brief   Buffer for the EP0 setup packets.
 */
static uint8_t ep0setup_buffer[8];

/**
 * @brief   EP0 initialization structure.
 */
static const USBEndpointConfig ep0config = {
  USB_EP_MODE_TYPE_CTRL,
  _usb_ep0setup,
  _usb_ep0in,
  _usb_ep0out,
  0x40,
  0x40,
  &ep0_state.in,
  &ep0_state.out,
  ep0setup_buffer
};

/*===========================================================================*/
/* Driver local functions.                                                   */
/*===========================================================================*/

/**
 * @brief   Resets the packet memory allocator.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 */
static void usb_pm_reset(USBDriver *usbp) {

  /* The first 64 bytes are reserved for the descriptors table. The effective
     available RAM for endpoint buffers is just 448 bytes.*/
  usbp->pmnext = 64;
}

/**
 * @brief   Resets the packet memory allocator.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] size      size of the packet buffer to allocate
 */
static uint32_t usb_pm_alloc(USBDriver *usbp, size_t size) {
  uint32_t next;

  next = usbp->pmnext;
  usbp->pmnext += size;
  chDbgAssert(usbp->pmnext <= USB_PMA_SIZE, "usb_pm_alloc(), #1", "PMA overflow");
  return next;
}

/**
 * @brief   Reads from a dedicated packet buffer.
 *
 * @param[in] udp       pointer to a @p stm32_usb_descriptor_t
 * @param[out] buf      buffer where to copy the packet data
 * @param[in] n         maximum number of bytes to copy. This value must
 *                      not exceed the maximum packet size for this endpoint.
 *
 * @notapi
 */
static void usb_packet_read_to_buffer(stm32_usb_descriptor_t *udp,
                                      uint8_t *buf, size_t n) {
  uint32_t *pmap= USB_ADDR2PTR(udp->RXADDR0);

  n = (n + 1) / 2;
  while (n > 0) {
    /* Note, this line relies on the Cortex-M3/M4 ability to perform
       unaligned word accesses.*/
    *(uint16_t *)buf = (uint16_t)*pmap++;
    buf += 2;
    n--;
  }
}

/**
 * @brief   Reads from a dedicated packet buffer.
 *
 * @param[in] udp       pointer to a @p stm32_usb_descriptor_t
 * @param[in] iqp       pointer to an @p InputQueue object
 * @param[in] n         maximum number of bytes to copy. This value must
 *                      not exceed the maximum packet size for this endpoint.
 *
 * @notapi
 */
static void usb_packet_read_to_queue(stm32_usb_descriptor_t *udp,
                                     InputQueue *iqp, size_t n) {
  size_t nhw;
  uint32_t *pmap= USB_ADDR2PTR(udp->RXADDR0);

  nhw = n / 2;
  while (nhw > 0) {
    uint32_t w;

    w = *pmap++;
    *iqp->q_wrptr++ = (uint8_t)w;
    if (iqp->q_wrptr >= iqp->q_top)
      iqp->q_wrptr = iqp->q_buffer;
    *iqp->q_wrptr++ = (uint8_t)(w >> 8);
    if (iqp->q_wrptr >= iqp->q_top)
      iqp->q_wrptr = iqp->q_buffer;
    nhw--;
  }
  /* Last byte for odd numbers.*/
  if ((n & 1) != 0) {
    *iqp->q_wrptr++ = (uint8_t)*pmap;
    if (iqp->q_wrptr >= iqp->q_top)
      iqp->q_wrptr = iqp->q_buffer;
  }

  /* Updating queue.*/
  chSysLockFromIsr();
  iqp->q_counter += n;
  while (notempty(&iqp->q_waiting))
    chSchReadyI(fifo_remove(&iqp->q_waiting))->p_u.rdymsg = Q_OK;
  chSysUnlockFromIsr();
}

/**
 * @brief   Writes to a dedicated packet buffer.
 *
 * @param[in] udp       pointer to a @p stm32_usb_descriptor_t
 * @param[in] buf       buffer where to fetch the packet data
 * @param[in] n         maximum number of bytes to copy. This value must
 *                      not exceed the maximum packet size for this endpoint.
 *
 * @notapi
 */
static void usb_packet_write_from_buffer(stm32_usb_descriptor_t *udp,
                                         const uint8_t *buf,
                                         size_t n) {
  uint32_t *pmap = USB_ADDR2PTR(udp->TXADDR0);

  udp->TXCOUNT0 = (uint16_t)n;
  n = (n + 1) / 2;
  while (n > 0) {
    /* Note, this line relies on the Cortex-M3/M4 ability to perform
       unaligned word accesses.*/
    *pmap++ = *(uint16_t *)buf;
    buf += 2;
    n--;
  }
}

/**
 * @brief   Writes to a dedicated packet buffer.
 *
 * @param[in] udp       pointer to a @p stm32_usb_descriptor_t
 * @param[in] buf       buffer where to fetch the packet data
 * @param[in] n         maximum number of bytes to copy. This value must
 *                      not exceed the maximum packet size for this endpoint.
 *
 * @notapi
 */
static void usb_packet_write_from_queue(stm32_usb_descriptor_t *udp,
                                        OutputQueue *oqp, size_t n) {
  size_t nhw;
  uint32_t *pmap = USB_ADDR2PTR(udp->TXADDR0);

  udp->TXCOUNT0 = (uint16_t)n;
  nhw = n / 2;
  while (nhw > 0) {
    uint32_t w;

    w  = (uint32_t)*oqp->q_rdptr++;
    if (oqp->q_rdptr >= oqp->q_top)
      oqp->q_rdptr = oqp->q_buffer;
    w |= (uint32_t)*oqp->q_rdptr++ << 8;
    if (oqp->q_rdptr >= oqp->q_top)
      oqp->q_rdptr = oqp->q_buffer;
    *pmap++ = w;
    nhw--;
  }

  /* Last byte for odd numbers.*/
  if ((n & 1) != 0) {
    *pmap = (uint32_t)*oqp->q_rdptr++;
    if (oqp->q_rdptr >= oqp->q_top)
      oqp->q_rdptr = oqp->q_buffer;
  }

  /* Updating queue. Note, the lock is done in this unusual way because this
     function can be called from both ISR and thread context so the kind
     of lock function to be invoked cannot be decided beforehand.*/
  port_lock();
  dbg_enter_lock();

  oqp->q_counter += n;
  while (notempty(&oqp->q_waiting))
    chSchReadyI(fifo_remove(&oqp->q_waiting))->p_u.rdymsg = Q_OK;

  dbg_leave_lock();
  port_unlock();
}

/**
 * @brief   Prepares for a receive transaction on an OUT endpoint.
 * @post    The endpoint is ready for @p usbStartReceiveI().
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @param[in] n         maximum number of bytes to copy
 *
 * @special
 */
static void usb_prepare_receive(USBDriver *usbp, usbep_t ep, size_t n) {
  USBOutEndpointState *osp = usbp->epc[ep]->out_state;

  osp->rxsize = n;
  osp->rxcnt  = 0;

  /* Transfer initialization.*/
  if (osp->rxsize == 0)         /* Special case for zero sized packets.*/
    osp->rxpkts = 1;
  else
    osp->rxpkts = (uint16_t)((n + usbp->epc[ep]->out_maxsize - 1) /
                             usbp->epc[ep]->out_maxsize);
}

/*===========================================================================*/
/* Driver interrupt handlers.                                                */
/*===========================================================================*/

#if STM32_USB_USE_USB1 || defined(__DOXYGEN__)
/**
 * @brief   USB high priority interrupt handler.
 *
 * @isr
 */
CH_IRQ_HANDLER(Vector8C) {

  CH_IRQ_PROLOGUE();

  CH_IRQ_EPILOGUE();
}

/**
 * @brief   USB low priority interrupt handler.
 *
 * @isr
 */
CH_IRQ_HANDLER(Vector90) {
  uint32_t istr;
  size_t n;
  USBDriver *usbp = &USBD1;

  CH_IRQ_PROLOGUE();

  istr = STM32_USB->ISTR;

  /* USB bus reset condition handling.*/
  if (istr & ISTR_RESET) {
    _usb_reset(usbp);
    _usb_isr_invoke_event_cb(usbp, USB_EVENT_RESET);
    STM32_USB->ISTR = ~ISTR_RESET;
  }

  /* USB bus SUSPEND condition handling.*/
  if (istr & ISTR_SUSP) {
    STM32_USB->CNTR |= CNTR_FSUSP;
    _usb_isr_invoke_event_cb(usbp, USB_EVENT_SUSPEND);
#if STM32_USB_LOW_POWER_ON_SUSPEND
    STM32_USB->CNTR |= CNTR_LP_MODE;
#endif
    STM32_USB->ISTR = ~ISTR_SUSP;
  }

  /* USB bus WAKEUP condition handling.*/
  if (istr & ISTR_WKUP) {
    uint32_t fnr = STM32_USB->FNR;
    if (!(fnr & FNR_RXDP)) {
      STM32_USB->CNTR &= ~CNTR_FSUSP;
      _usb_isr_invoke_event_cb(usbp, USB_EVENT_WAKEUP);
    }
#if STM32_USB_LOW_POWER_ON_SUSPEND
    else {
      /* Just noise, going back in SUSPEND mode, reference manual 22.4.5,
         table 169.*/
      STM32_USB->CNTR |= CNTR_LP_MODE;
    }
#endif
    STM32_USB->ISTR = ~ISTR_WKUP;
  }

  /* SOF handling.*/
  if (istr & ISTR_SOF) {
    _usb_isr_invoke_sof_cb(usbp);
    STM32_USB->ISTR = ~ISTR_SOF;
  }

  /* Endpoint events handling.*/
  while (istr & ISTR_CTR) {
    uint32_t ep;
    uint32_t epr = STM32_USB->EPR[ep = istr & ISTR_EP_ID_MASK];
    const USBEndpointConfig *epcp = usbp->epc[ep];

    if (epr & EPR_CTR_TX) {
      /* IN endpoint, transmission.*/
      EPR_CLEAR_CTR_TX(ep);

      n = (size_t)USB_GET_DESCRIPTOR(ep)->TXCOUNT0;
      epcp->in_state->mode.linear.txbuf  += n;
      epcp->in_state->txcnt              += n;
      epcp->in_state->txsize             -= n;
      if (epcp->in_state->txsize > 0) {
        /* Transfer not completed, there are more packets to send.*/
        if (epcp->in_state->txsize > epcp->in_maxsize)
          n = epcp->in_maxsize;
        else
          n = epcp->in_state->txsize;

        if (epcp->in_state->txqueued)
          usb_packet_write_from_queue(USB_GET_DESCRIPTOR(ep),
                                      epcp->in_state->mode.queue.txqueue,
                                      n);
        else
          usb_packet_write_from_buffer(USB_GET_DESCRIPTOR(ep),
                                       epcp->in_state->mode.linear.txbuf,
                                       n);
        chSysLockFromIsr();
        usb_lld_start_in(usbp, ep);
        chSysUnlockFromIsr();
      }
      else {
        /* Transfer completed, invokes the callback.*/
        _usb_isr_invoke_in_cb(usbp, ep);
      }
    }
    if (epr & EPR_CTR_RX) {
      EPR_CLEAR_CTR_RX(ep);
      /* OUT endpoint, receive.*/
      if (epr & EPR_SETUP) {
        /* Setup packets handling, setup packets are handled using a
           specific callback.*/
        _usb_isr_invoke_setup_cb(usbp, ep);
      }
      else {
        stm32_usb_descriptor_t *udp = USB_GET_DESCRIPTOR(ep);
        n = (size_t)udp->RXCOUNT0 & RXCOUNT_COUNT_MASK;

        /* Reads the packet into the defined buffer.*/
        if (epcp->out_state->rxqueued)
          usb_packet_read_to_queue(udp,
                                   epcp->out_state->mode.queue.rxqueue,
                                   n);
        else
          usb_packet_read_to_buffer(udp,
                                    epcp->out_state->mode.linear.rxbuf,
                                    n);

        /* Transaction data updated.*/
        epcp->out_state->mode.linear.rxbuf  += n;
        epcp->out_state->rxcnt              += n;
        epcp->out_state->rxsize             -= n;
        epcp->out_state->rxpkts             -= 1;
        if (epcp->out_state->rxpkts > 0) {
          /* Transfer not completed, there are more packets to receive.*/
          EPR_SET_STAT_RX(ep, EPR_STAT_RX_VALID);
        }
        else {
          /* Transfer completed, invokes the callback.*/
          _usb_isr_invoke_out_cb(usbp, ep);
        }
      }
    }
    istr = STM32_USB->ISTR;
  }

  CH_IRQ_EPILOGUE();
}
#endif

/*===========================================================================*/
/* Driver exported functions.                                                */
/*===========================================================================*/

/**
 * @brief   Low level USB driver initialization.
 *
 * @notapi
 */
void usb_lld_init(void) {

  /* Driver initialization.*/
  usbObjectInit(&USBD1);
}

/**
 * @brief   Configures and activates the USB peripheral.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 *
 * @notapi
 */
void usb_lld_start(USBDriver *usbp) {

  if (usbp->state == USB_STOP) {
    /* Clock activation.*/
#if STM32_USB_USE_USB1
    if (&USBD1 == usbp) {
      /* USB clock enabled.*/
      rccEnableUSB(FALSE);
      /* Powers up the transceiver while holding the USB in reset state.*/
      STM32_USB->CNTR = CNTR_FRES;
      /* Enabling the USB IRQ vectors, this also gives enough time to allow
         the transceiver power up (1uS).*/
      nvicEnableVector(19,
                       CORTEX_PRIORITY_MASK(STM32_USB_USB1_HP_IRQ_PRIORITY));
      nvicEnableVector(20,
                       CORTEX_PRIORITY_MASK(STM32_USB_USB1_LP_IRQ_PRIORITY));
      /* Releases the USB reset.*/
      STM32_USB->CNTR = 0;
    }
#endif
    /* Reset procedure enforced on driver start.*/
    _usb_reset(usbp);
  }
  /* Configuration.*/
}

/**
 * @brief   Deactivates the USB peripheral.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 *
 * @notapi
 */
void usb_lld_stop(USBDriver *usbp) {

  /* If in ready state then disables the USB clock.*/
  if (usbp->state == USB_STOP) {
#if STM32_USB_USE_USB1
    if (&USBD1 == usbp) {
      nvicDisableVector(19);
      nvicDisableVector(20);
      STM32_USB->CNTR = CNTR_PDWN | CNTR_FRES;
      rccDisableUSB(FALSE);
    }
#endif
  }
}

/**
 * @brief   USB low level reset routine.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 *
 * @notapi
 */
void usb_lld_reset(USBDriver *usbp) {
  uint32_t cntr;

  /* Post reset initialization.*/
  STM32_USB->BTABLE = 0;
  STM32_USB->ISTR   = 0;
  STM32_USB->DADDR  = DADDR_EF;
  cntr              = /*CNTR_ESOFM | */ CNTR_RESETM  | CNTR_SUSPM |
                      CNTR_WKUPM | /*CNTR_ERRM | CNTR_PMAOVRM |*/ CNTR_CTRM;
  /* The SOF interrupt is only enabled if a callback is defined for
     this service because it is an high rate source.*/
  if (usbp->config->sof_cb != NULL)
    cntr |= CNTR_SOFM;
  STM32_USB->CNTR = cntr;

  /* Resets the packet memory allocator.*/
  usb_pm_reset(usbp);

  /* EP0 initialization.*/
  usbp->epc[0] = &ep0config;
  usb_lld_init_endpoint(usbp, 0);
}

/**
 * @brief   Sets the USB address.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 *
 * @notapi
 */
void usb_lld_set_address(USBDriver *usbp) {

  STM32_USB->DADDR = (uint32_t)(usbp->address) | DADDR_EF;
}

/**
 * @brief   Enables an endpoint.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 *
 * @notapi
 */
void usb_lld_init_endpoint(USBDriver *usbp, usbep_t ep) {
  uint16_t nblocks, epr;
  stm32_usb_descriptor_t *dp;
  const USBEndpointConfig *epcp = usbp->epc[ep];

  /* Setting the endpoint type.*/
  switch (epcp->ep_mode & USB_EP_MODE_TYPE) {
  case USB_EP_MODE_TYPE_ISOC:
    epr = EPR_EP_TYPE_ISO;
    break;
  case USB_EP_MODE_TYPE_BULK:
    epr = EPR_EP_TYPE_BULK;
    break;
  case USB_EP_MODE_TYPE_INTR:
    epr = EPR_EP_TYPE_INTERRUPT;
    break;
  default:
    epr = EPR_EP_TYPE_CONTROL;
  }

  /* IN endpoint initially in NAK mode.*/
  if (epcp->in_cb != NULL)
    epr |= EPR_STAT_TX_NAK;

  /* OUT endpoint initially in NAK mode.*/
  if (epcp->out_cb != NULL)
    epr |= EPR_STAT_RX_NAK;

  /* EPxR register setup.*/
  EPR_SET(ep, epr | ep);
  EPR_TOGGLE(ep, epr);

  /* Endpoint size and address initialization.*/
  if (epcp->out_maxsize > 62)
    nblocks = (((((epcp->out_maxsize - 1) | 0x1f) + 1) / 32) << 10) |
              0x8000;
  else
    nblocks = ((((epcp->out_maxsize - 1) | 1) + 1) / 2) << 10;
  dp = USB_GET_DESCRIPTOR(ep);
  dp->TXCOUNT0 = 0;
  dp->RXCOUNT0 = nblocks;
  dp->TXADDR0  = usb_pm_alloc(usbp, epcp->in_maxsize);
  dp->RXADDR0  = usb_pm_alloc(usbp, epcp->out_maxsize);
}

/**
 * @brief   Disables all the active endpoints except the endpoint zero.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 *
 * @notapi
 */
void usb_lld_disable_endpoints(USBDriver *usbp) {
  unsigned i;

  /* Resets the packet memory allocator.*/
  usb_pm_reset(usbp);

  /* Disabling all endpoints.*/
  for (i = 1; i <= USB_ENDOPOINTS_NUMBER; i++) {
    EPR_TOGGLE(i, 0);
    EPR_SET(i, 0);
  }
}

/**
 * @brief   Returns the status of an OUT endpoint.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @return              The endpoint status.
 * @retval EP_STATUS_DISABLED The endpoint is not active.
 * @retval EP_STATUS_STALLED  The endpoint is stalled.
 * @retval EP_STATUS_ACTIVE   The endpoint is active.
 *
 * @notapi
 */
usbepstatus_t usb_lld_get_status_out(USBDriver *usbp, usbep_t ep) {

  (void)usbp;
  switch (STM32_USB->EPR[ep] & EPR_STAT_RX_MASK) {
  case EPR_STAT_RX_DIS:
    return EP_STATUS_DISABLED;
  case EPR_STAT_RX_STALL:
    return EP_STATUS_STALLED;
  default:
    return EP_STATUS_ACTIVE;
  }
}

/**
 * @brief   Returns the status of an IN endpoint.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @return              The endpoint status.
 * @retval EP_STATUS_DISABLED The endpoint is not active.
 * @retval EP_STATUS_STALLED  The endpoint is stalled.
 * @retval EP_STATUS_ACTIVE   The endpoint is active.
 *
 * @notapi
 */
usbepstatus_t usb_lld_get_status_in(USBDriver *usbp, usbep_t ep) {

  (void)usbp;
  switch (STM32_USB->EPR[ep] & EPR_STAT_TX_MASK) {
  case EPR_STAT_TX_DIS:
    return EP_STATUS_DISABLED;
  case EPR_STAT_TX_STALL:
    return EP_STATUS_STALLED;
  default:
    return EP_STATUS_ACTIVE;
  }
}

/**
 * @brief   Reads a setup packet from the dedicated packet buffer.
 * @details This function must be invoked in the context of the @p setup_cb
 *          callback in order to read the received setup packet.
 * @pre     In order to use this function the endpoint must have been
 *          initialized as a control endpoint.
 * @post    The endpoint is ready to accept another packet.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @param[out] buf      buffer where to copy the packet data
 *
 * @notapi
 */
void usb_lld_read_setup(USBDriver *usbp, usbep_t ep, uint8_t *buf) {
  uint32_t *pmap;
  stm32_usb_descriptor_t *udp;
  uint32_t n;

  (void)usbp;
  udp = USB_GET_DESCRIPTOR(ep);
  pmap = USB_ADDR2PTR(udp->RXADDR0);
  for (n = 0; n < 4; n++) {
    *(uint16_t *)buf = (uint16_t)*pmap++;
    buf += 2;
  }
}

/**
 * @brief   Prepares for a receive operation.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @param[out] buf      buffer where to copy the received data
 * @param[in] n         maximum number of bytes to copy
 *
 * @notapi
 */
void usb_lld_prepare_receive(USBDriver *usbp, usbep_t ep,
                             uint8_t *buf, size_t n) {
  USBOutEndpointState *osp = usbp->epc[ep]->out_state;

  osp->rxqueued           = FALSE;
  osp->mode.linear.rxbuf  = buf;
  usb_prepare_receive(usbp, ep, n);
}

/**
 * @brief   Prepares for a transmit operation.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @param[in] buf       buffer where to fetch the data to be transmitted
 * @param[in] n         maximum number of bytes to copy
 *
 * @notapi
 */
void usb_lld_prepare_transmit(USBDriver *usbp, usbep_t ep,
                              const uint8_t *buf, size_t n) {
  USBInEndpointState *isp = usbp->epc[ep]->in_state;

  isp->txqueued           = FALSE;
  isp->mode.linear.txbuf  = buf;
  isp->txsize = n;
  isp->txcnt  = 0;

  /* Transfer initialization.*/
  if (n > (size_t)usbp->epc[ep]->in_maxsize)
    n = (size_t)usbp->epc[ep]->in_maxsize;

  usb_packet_write_from_buffer(USB_GET_DESCRIPTOR(ep),
                               isp->mode.linear.txbuf, n);
}

/**
 * @brief   Prepares for a receive transaction on an OUT endpoint.
 * @post    The endpoint is ready for @p usbStartReceiveI().
 * @note    The receive transaction size is equal to the space in the queue
 *          rounded to the lower multiple of a packet size. Make sure there
 *          is room for at least one packet in the queue before starting
 *          the receive operation.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @param[in] iq        input queue to be filled with incoming data
 * @param[in] n         maximum number of bytes to copy
 *
 * @special
 */
void usb_lld_prepare_queued_receive(USBDriver *usbp, usbep_t ep,
                                    InputQueue *iq, size_t n) {
  USBOutEndpointState *osp = usbp->epc[ep]->out_state;

  osp->rxqueued           = TRUE;
  osp->mode.queue.rxqueue = iq;
  usb_prepare_receive(usbp, ep, n);
}

/**
 * @brief   Prepares for a transmit transaction on an IN endpoint.
 * @post    The endpoint is ready for @p usbStartTransmitI().
 * @note    The transmit transaction size is equal to the data contained
 *          in the queue.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 * @param[in] oq        output queue to be fetched for outgoing data
 * @param[in] n         maximum number of bytes to copy
 *
 * @special
 */
void usb_lld_prepare_queued_transmit(USBDriver *usbp, usbep_t ep,
                                     OutputQueue *oq, size_t n) {
  USBInEndpointState *isp = usbp->epc[ep]->in_state;

  isp->txqueued           = TRUE;
  isp->mode.queue.txqueue = oq;
  isp->txsize = n;
  isp->txcnt  = 0;

  /* Transfer initialization.*/
  if (n > (size_t)usbp->epc[ep]->in_maxsize)
    n = (size_t)usbp->epc[ep]->in_maxsize;

  usb_packet_write_from_queue(USB_GET_DESCRIPTOR(ep),
                              isp->mode.queue.txqueue, n);
}

/**
 * @brief   Starts a receive operation on an OUT endpoint.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 *
 * @notapi
 */
void usb_lld_start_out(USBDriver *usbp, usbep_t ep) {

  (void)usbp;

  EPR_SET_STAT_RX(ep, EPR_STAT_RX_VALID);
}

/**
 * @brief   Starts a transmit operation on an IN endpoint.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 *
 * @notapi
 */
void usb_lld_start_in(USBDriver *usbp, usbep_t ep) {

  (void)usbp;

  EPR_SET_STAT_TX(ep, EPR_STAT_TX_VALID);
}

/**
 * @brief   Brings an OUT endpoint in the stalled state.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 *
 * @notapi
 */
void usb_lld_stall_out(USBDriver *usbp, usbep_t ep) {

  (void)usbp;

  EPR_SET_STAT_RX(ep, EPR_STAT_RX_STALL);
}

/**
 * @brief   Brings an IN endpoint in the stalled state.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 *
 * @notapi
 */
void usb_lld_stall_in(USBDriver *usbp, usbep_t ep) {

  (void)usbp;

  EPR_SET_STAT_TX(ep, EPR_STAT_TX_STALL);
}

/**
 * @brief   Brings an OUT endpoint in the active state.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 *
 * @notapi
 */
void usb_lld_clear_out(USBDriver *usbp, usbep_t ep) {

  (void)usbp;

  /* Makes sure to not put to NAK an endpoint that is already
     transferring.*/
  if ((STM32_USB->EPR[ep] & EPR_STAT_RX_MASK) != EPR_STAT_RX_VALID)
    EPR_SET_STAT_TX(ep, EPR_STAT_RX_NAK);
}

/**
 * @brief   Brings an IN endpoint in the active state.
 *
 * @param[in] usbp      pointer to the @p USBDriver object
 * @param[in] ep        endpoint number
 *
 * @notapi
 */
void usb_lld_clear_in(USBDriver *usbp, usbep_t ep) {

  (void)usbp;

  /* Makes sure to not put to NAK an endpoint that is already
     transferring.*/
  if ((STM32_USB->EPR[ep] & EPR_STAT_TX_MASK) != EPR_STAT_TX_VALID)
    EPR_SET_STAT_TX(ep, EPR_STAT_TX_NAK);
}

#endif /* HAL_USE_USB */

/** @} */