src/class/cdc/cdc_device.c

/* 
 * The MIT License (MIT)
 *
 * Copyright (c) 2019 Ha Thach (tinyusb.org)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * This file is part of the TinyUSB stack.
 */

#include "tusb_option.h"

#if (TUSB_OPT_DEVICE_ENABLED && CFG_TUD_CDC)

#include "device/usbd.h"
#include "device/usbd_pvt.h"

#include "cdc_device.h"

//--------------------------------------------------------------------+
// MACRO CONSTANT TYPEDEF
//--------------------------------------------------------------------+
enum
{
  BULK_PACKET_SIZE = (TUD_OPT_HIGH_SPEED ? 512 : 64)
};

typedef struct
{
  uint8_t itf_num;
  uint8_t ep_notif;
  uint8_t ep_in;
  uint8_t ep_out;

  // Bit 0:  DTR (Data Terminal Ready), Bit 1: RTS (Request to Send)
  uint8_t line_state;

  /*------------- From this point, data is not cleared by bus reset -------------*/
  char    wanted_char;
  cdc_line_coding_t line_coding;

  // FIFO
  tu_fifo_t rx_ff;
  tu_fifo_t tx_ff;

  uint8_t rx_ff_buf[CFG_TUD_CDC_RX_BUFSIZE];
  uint8_t tx_ff_buf[CFG_TUD_CDC_TX_BUFSIZE];

#if CFG_FIFO_MUTEX
  osal_mutex_def_t rx_ff_mutex;
  osal_mutex_def_t tx_ff_mutex;
#endif

  // Endpoint Transfer buffer
  CFG_TUSB_MEM_ALIGN uint8_t epout_buf[CFG_TUD_CDC_EP_BUFSIZE];
  CFG_TUSB_MEM_ALIGN uint8_t epin_buf[CFG_TUD_CDC_EP_BUFSIZE];

}cdcd_interface_t;

#define ITF_MEM_RESET_SIZE   offsetof(cdcd_interface_t, wanted_char)

//--------------------------------------------------------------------+
// INTERNAL OBJECT & FUNCTION DECLARATION
//--------------------------------------------------------------------+
CFG_TUSB_MEM_SECTION static cdcd_interface_t _cdcd_itf[CFG_TUD_CDC];

static bool _prep_out_transaction (cdcd_interface_t* p_cdc)
{
  uint8_t const rhport = TUD_OPT_RHPORT;
  uint16_t available = tu_fifo_remaining(&p_cdc->rx_ff);

  // Prepare for incoming data but only allow what we can store in the ring buffer.
  // TODO Actually we can still carry out the transfer, keeping count of received bytes
  // and slowly move it to the FIFO when read().
  // This pre-check reduces endpoint claiming
  TU_VERIFY(available >= sizeof(p_cdc->epout_buf));

  // claim endpoint
  TU_VERIFY(usbd_edpt_claim(rhport, p_cdc->ep_out));

  // fifo can be changed before endpoint is claimed
  available = tu_fifo_remaining(&p_cdc->rx_ff);

  if ( available >= sizeof(p_cdc->epout_buf) )
  {
    return usbd_edpt_xfer(rhport, p_cdc->ep_out, p_cdc->epout_buf, sizeof(p_cdc->epout_buf));
  }else
  {
    // Release endpoint since we don't make any transfer
    usbd_edpt_release(rhport, p_cdc->ep_out);

    return false;
  }
}

//--------------------------------------------------------------------+
// APPLICATION API
//--------------------------------------------------------------------+
bool tud_cdc_n_connected(uint8_t itf)
{
  // DTR (bit 0) active  is considered as connected
  return tud_ready() && tu_bit_test(_cdcd_itf[itf].line_state, 0);
}

uint8_t tud_cdc_n_get_line_state (uint8_t itf)
{
  return _cdcd_itf[itf].line_state;
}

void tud_cdc_n_get_line_coding (uint8_t itf, cdc_line_coding_t* coding)
{
  (*coding) = _cdcd_itf[itf].line_coding;
}

void tud_cdc_n_set_wanted_char (uint8_t itf, char wanted)
{
  _cdcd_itf[itf].wanted_char = wanted;
}


//--------------------------------------------------------------------+
// READ API
//--------------------------------------------------------------------+
uint32_t tud_cdc_n_available(uint8_t itf)
{
  return tu_fifo_count(&_cdcd_itf[itf].rx_ff);
}

uint32_t tud_cdc_n_read(uint8_t itf, void* buffer, uint32_t bufsize)
{
  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
  uint32_t num_read = tu_fifo_read_n(&p_cdc->rx_ff, buffer, bufsize);
  _prep_out_transaction(p_cdc);
  return num_read;
}

bool tud_cdc_n_peek(uint8_t itf, uint8_t* chr)
{
  return tu_fifo_peek(&_cdcd_itf[itf].rx_ff, chr);
}

void tud_cdc_n_read_flush (uint8_t itf)
{
  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
  tu_fifo_clear(&p_cdc->rx_ff);
  _prep_out_transaction(p_cdc);
}

//--------------------------------------------------------------------+
// WRITE API
//--------------------------------------------------------------------+
uint32_t tud_cdc_n_write(uint8_t itf, void const* buffer, uint32_t bufsize)
{
  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
  uint16_t ret = tu_fifo_write_n(&p_cdc->tx_ff, buffer, bufsize);

  // flush if queue more than packet size
  if ( tu_fifo_count(&p_cdc->tx_ff) >= BULK_PACKET_SIZE )
  {
    tud_cdc_n_write_flush(itf);
  }

  return ret;
}

uint32_t tud_cdc_n_write_flush (uint8_t itf)
{
  cdcd_interface_t* p_cdc = &_cdcd_itf[itf];

  // Skip if usb is not ready yet
  TU_VERIFY( tud_ready(), 0 );

  // No data to send
  if ( !tu_fifo_count(&p_cdc->tx_ff) ) return 0;

  uint8_t const rhport = TUD_OPT_RHPORT;

  // Claim the endpoint
  TU_VERIFY( usbd_edpt_claim(rhport, p_cdc->ep_in), 0 );

  // Pull data from FIFO
  uint16_t const count = tu_fifo_read_n(&p_cdc->tx_ff, p_cdc->epin_buf, sizeof(p_cdc->epin_buf));

  if ( count )
  {
    TU_ASSERT( usbd_edpt_xfer(rhport, p_cdc->ep_in, p_cdc->epin_buf, count), 0 );
    return count;
  }else
  {
    // Release endpoint since we don't make any transfer
    // Note: data is dropped if terminal is not connected
    usbd_edpt_release(rhport, p_cdc->ep_in);
    return 0;
  }
}

uint32_t tud_cdc_n_write_available (uint8_t itf)
{
  return tu_fifo_remaining(&_cdcd_itf[itf].tx_ff);
}

bool tud_cdc_n_write_clear (uint8_t itf)
{
  return tu_fifo_clear(&_cdcd_itf[itf].tx_ff);
}

//--------------------------------------------------------------------+
// USBD Driver API
//--------------------------------------------------------------------+
void cdcd_init(void)
{
  tu_memclr(_cdcd_itf, sizeof(_cdcd_itf));

  for(uint8_t i=0; i<CFG_TUD_CDC; i++)
  {
    cdcd_interface_t* p_cdc = &_cdcd_itf[i];

    p_cdc->wanted_char = (char) -1;

    // default line coding is : stop bit = 1, parity = none, data bits = 8
    p_cdc->line_coding.bit_rate  = 115200;
    p_cdc->line_coding.stop_bits = 0;
    p_cdc->line_coding.parity    = 0;
    p_cdc->line_coding.data_bits = 8;

    // Config RX fifo
    tu_fifo_config(&p_cdc->rx_ff, p_cdc->rx_ff_buf, TU_ARRAY_SIZE(p_cdc->rx_ff_buf), 1, false);

    // Config TX fifo as overwritable at initialization and will be changed to non-overwritable
    // if terminal supports DTR bit. Without DTR we do not know if data is actually polled by terminal.
    // In this way, the most current data is prioritized.
    tu_fifo_config(&p_cdc->tx_ff, p_cdc->tx_ff_buf, TU_ARRAY_SIZE(p_cdc->tx_ff_buf), 1, true);

#if CFG_FIFO_MUTEX
    tu_fifo_config_mutex(&p_cdc->rx_ff, NULL, osal_mutex_create(&p_cdc->rx_ff_mutex));
    tu_fifo_config_mutex(&p_cdc->tx_ff, osal_mutex_create(&p_cdc->tx_ff_mutex), NULL);
#endif
  }
}

void cdcd_reset(uint8_t rhport)
{
  (void) rhport;

  for(uint8_t i=0; i<CFG_TUD_CDC; i++)
  {
    cdcd_interface_t* p_cdc = &_cdcd_itf[i];

    tu_memclr(p_cdc, ITF_MEM_RESET_SIZE);
    tu_fifo_clear(&p_cdc->rx_ff);
    tu_fifo_clear(&p_cdc->tx_ff);
    tu_fifo_set_overwritable(&p_cdc->tx_ff, true);
  }
}

uint16_t cdcd_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len)
{
  // Only support ACM subclass
  TU_VERIFY( TUSB_CLASS_CDC                           == itf_desc->bInterfaceClass &&
             CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL == itf_desc->bInterfaceSubClass, 0);

  // Find available interface
  cdcd_interface_t * p_cdc = NULL;
  for(uint8_t cdc_id=0; cdc_id<CFG_TUD_CDC; cdc_id++)
  {
    if ( _cdcd_itf[cdc_id].ep_in == 0 )
    {
      p_cdc = &_cdcd_itf[cdc_id];
      break;
    }
  }
  TU_ASSERT(p_cdc, 0);

  //------------- Control Interface -------------//
  p_cdc->itf_num = itf_desc->bInterfaceNumber;

  uint16_t drv_len = sizeof(tusb_desc_interface_t);
  uint8_t const * p_desc = tu_desc_next( itf_desc );

  // Communication Functional Descriptors
  while ( TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc) && drv_len <= max_len )
  {
    drv_len += tu_desc_len(p_desc);
    p_desc   = tu_desc_next(p_desc);
  }

  if ( TUSB_DESC_ENDPOINT == tu_desc_type(p_desc) )
  {
    // notification endpoint
    tusb_desc_endpoint_t const * desc_ep = (tusb_desc_endpoint_t const *) p_desc;

    TU_ASSERT( usbd_edpt_open(rhport, desc_ep), 0 );
    p_cdc->ep_notif = desc_ep->bEndpointAddress;

    drv_len += tu_desc_len(p_desc);
    p_desc   = tu_desc_next(p_desc);
  }

  //------------- Data Interface (if any) -------------//
  if ( (TUSB_DESC_INTERFACE == tu_desc_type(p_desc)) &&
       (TUSB_CLASS_CDC_DATA == ((tusb_desc_interface_t const *) p_desc)->bInterfaceClass) )
  {
    // next to endpoint descriptor
    drv_len += tu_desc_len(p_desc);
    p_desc   = tu_desc_next(p_desc);

    // Open endpoint pair
    TU_ASSERT( usbd_open_edpt_pair(rhport, p_desc, 2, TUSB_XFER_BULK, &p_cdc->ep_out, &p_cdc->ep_in), 0 );

    drv_len += 2*sizeof(tusb_desc_endpoint_t);
  }

  // Prepare for incoming data
  _prep_out_transaction(p_cdc);

  return drv_len;
}

// Invoked when a control transfer occurred on an interface of this class
// Driver response accordingly to the request and the transfer stage (setup/data/ack)
// return false to stall control endpoint (e.g unsupported request)
bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request)
{
  // Handle class request only
  TU_VERIFY(request->bmRequestType_bit.type == TUSB_REQ_TYPE_CLASS);

  uint8_t itf = 0;
  cdcd_interface_t* p_cdc = _cdcd_itf;

  // Identify which interface to use
  for ( ; ; itf++, p_cdc++)
  {
    if (itf >= TU_ARRAY_SIZE(_cdcd_itf)) return false;

    if ( p_cdc->itf_num == request->wIndex ) break;
  }

  switch ( request->bRequest )
  {
    case CDC_REQUEST_SET_LINE_CODING:
      if (stage == CONTROL_STAGE_SETUP)
      {
        TU_LOG2("  Set Line Coding\r\n");
        tud_control_xfer(rhport, request, &p_cdc->line_coding, sizeof(cdc_line_coding_t));
      }
      else if ( stage == CONTROL_STAGE_ACK)
      {
        if ( tud_cdc_line_coding_cb ) tud_cdc_line_coding_cb(itf, &p_cdc->line_coding);
      }
    break;

    case CDC_REQUEST_GET_LINE_CODING:
      if (stage == CONTROL_STAGE_SETUP)
      {
        TU_LOG2("  Get Line Coding\r\n");
        tud_control_xfer(rhport, request, &p_cdc->line_coding, sizeof(cdc_line_coding_t));
      }
    break;

    case CDC_REQUEST_SET_CONTROL_LINE_STATE:
      if (stage == CONTROL_STAGE_SETUP)
      {
        tud_control_status(rhport, request);
      }
      else if (stage == CONTROL_STAGE_ACK)
      {
        // CDC PSTN v1.2 section 6.3.12
        // Bit 0: Indicates if DTE is present or not.
        //        This signal corresponds to V.24 signal 108/2 and RS-232 signal DTR (Data Terminal Ready)
        // Bit 1: Carrier control for half-duplex modems.
        //        This signal corresponds to V.24 signal 105 and RS-232 signal RTS (Request to Send)
        bool const dtr = tu_bit_test(request->wValue, 0);
        bool const rts = tu_bit_test(request->wValue, 1);

        p_cdc->line_state = (uint8_t) request->wValue;
        
        // Disable fifo overwriting if DTR bit is set
        tu_fifo_set_overwritable(&p_cdc->tx_ff, !dtr);

        TU_LOG2("  Set Control Line State: DTR = %d, RTS = %d\r\n", dtr, rts);

        // Invoke callback
        if ( tud_cdc_line_state_cb ) tud_cdc_line_state_cb(itf, dtr, rts);
      }
    break;
    case CDC_REQUEST_SEND_BREAK:
      if (stage == CONTROL_STAGE_SETUP)
      {
        tud_control_status(rhport, request);
      }
      else if (stage == CONTROL_STAGE_ACK)
      {
        TU_LOG2("  Send Break\r\n");
        if ( tud_cdc_send_break_cb ) tud_cdc_send_break_cb(itf, request->wValue);
      }
    break;

    default: return false; // stall unsupported request
  }

  return true;
}

bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
{
  (void) result;

  uint8_t itf;
  cdcd_interface_t* p_cdc;

  // Identify which interface to use
  for (itf = 0; itf < CFG_TUD_CDC; itf++)
  {
    p_cdc = &_cdcd_itf[itf];
    if ( ( ep_addr == p_cdc->ep_out ) || ( ep_addr == p_cdc->ep_in ) ) break;
  }
  TU_ASSERT(itf < CFG_TUD_CDC);

  // Received new data
  if ( ep_addr == p_cdc->ep_out )
  {
    tu_fifo_write_n(&p_cdc->rx_ff, &p_cdc->epout_buf, xferred_bytes);
    
    // Check for wanted char and invoke callback if needed
    if ( tud_cdc_rx_wanted_cb && (((signed char) p_cdc->wanted_char) != -1) )
    {
      for ( uint32_t i = 0; i < xferred_bytes; i++ )
      {
        if ( (p_cdc->wanted_char == p_cdc->epout_buf[i]) && !tu_fifo_empty(&p_cdc->rx_ff) )
        {
          tud_cdc_rx_wanted_cb(itf, p_cdc->wanted_char);
        }
      }
    }
    
    // invoke receive callback (if there is still data)
    if (tud_cdc_rx_cb && !tu_fifo_empty(&p_cdc->rx_ff) ) tud_cdc_rx_cb(itf);
    
    // prepare for OUT transaction
    _prep_out_transaction(p_cdc);
  }
  
  // Data sent to host, we continue to fetch from tx fifo to send.
  // Note: This will cause incorrect baudrate set in line coding.
  //       Though maybe the baudrate is not really important !!!
  if ( ep_addr == p_cdc->ep_in )
  {
    // invoke transmit callback to possibly refill tx fifo
    if ( tud_cdc_tx_complete_cb ) tud_cdc_tx_complete_cb(itf);

    if ( 0 == tud_cdc_n_write_flush(itf) )
    {
      // If there is no data left, a ZLP should be sent if
      // xferred_bytes is multiple of EP Packet size and not zero
      if ( !tu_fifo_count(&p_cdc->tx_ff) && xferred_bytes && (0 == (xferred_bytes & (BULK_PACKET_SIZE-1))) )
      {
        if ( usbd_edpt_claim(rhport, p_cdc->ep_in) )
        {
          usbd_edpt_xfer(rhport, p_cdc->ep_in, NULL, 0);
        }
      }
    }
  }

  // nothing to do with notif endpoint for now

  return true;
}

#endif