CDC.cpp

/* Copyright (c) 2011, Peter Barrett  
**  
** Permission to use, copy, modify, and/or distribute this software for  
** any purpose with or without fee is hereby granted, provided that the  
** above copyright notice and this permission notice appear in all copies.  
** 
** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL  
** WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED  
** WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR  
** BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES  
** OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,  
** WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,  
** ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS  
** SOFTWARE.  
*/

#include "USBAPI.h"
#include <avr/wdt.h>
#include <util/atomic.h>

#if defined(USBCON)

typedef struct
{
  u32 dwDTERate;
  u8  bCharFormat;
  u8  bParityType;
  u8  bDataBits;
  u8  lineState;
} LineInfo;

static volatile LineInfo _usbLineInfo = { 57600, 0x00, 0x00, 0x00, 0x00 };
static volatile int32_t breakValue = -1;

bool _updatedLUFAbootloader = false;

#define WEAK __attribute__ ((weak))

extern const CDCDescriptor _cdcInterface PROGMEM;
const CDCDescriptor _cdcInterface =
{
  D_IAD(0,2,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,1),

  //  CDC communication interface
  D_INTERFACE(CDC_ACM_INTERFACE,1,CDC_COMMUNICATION_INTERFACE_CLASS,CDC_ABSTRACT_CONTROL_MODEL,0),
  D_CDCCS(CDC_HEADER,0x10,0x01),                // Header (1.10 bcd)
  D_CDCCS(CDC_CALL_MANAGEMENT,1,1),             // Device handles call management (not)
  D_CDCCS4(CDC_ABSTRACT_CONTROL_MANAGEMENT,6),        // SET_LINE_CODING, GET_LINE_CODING, SET_CONTROL_LINE_STATE supported
  D_CDCCS(CDC_UNION,CDC_ACM_INTERFACE,CDC_DATA_INTERFACE),  // Communication interface is master, data interface is slave 0
  D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_ACM),USB_ENDPOINT_TYPE_INTERRUPT,0x10,0x40),

  //  CDC data interface
  D_INTERFACE(CDC_DATA_INTERFACE,2,CDC_DATA_INTERFACE_CLASS,0,0),
  D_ENDPOINT(USB_ENDPOINT_OUT(CDC_ENDPOINT_OUT),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0),
  D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_IN ),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0)
};

int CDC_GetInterface(u8* interfaceNum)
{
  interfaceNum[0] += 2; // uses 2
  return USB_SendControl(TRANSFER_PGM,&_cdcInterface,sizeof(_cdcInterface));
}

bool CDC_Setup(USBSetup& setup)
{
  u8 r = setup.bRequest;
  u8 requestType = setup.bmRequestType;

  if (REQUEST_DEVICETOHOST_CLASS_INTERFACE == requestType)
  {
    if (CDC_GET_LINE_CODING == r)
    {
      USB_SendControl(0,(void*)&_usbLineInfo,7);
      return true;
    }
  }

  if (REQUEST_HOSTTODEVICE_CLASS_INTERFACE == requestType)
  {
    if (CDC_SEND_BREAK == r)
    {
      breakValue = ((uint16_t)setup.wValueH << 8) | setup.wValueL;
    }

    if (CDC_SET_LINE_CODING == r)
    {
      USB_RecvControl((void*)&_usbLineInfo,7);
    }

    if (CDC_SET_CONTROL_LINE_STATE == r)
    {
      _usbLineInfo.lineState = setup.wValueL;
    }

    if (CDC_SET_LINE_CODING == r || CDC_SET_CONTROL_LINE_STATE == r)
    {
      // auto-reset into the bootloader is triggered when the port, already 
      // open at 1200 bps, is closed.  this is the signal to start the watchdog
      // with a relatively long period so it can finish housekeeping tasks
      // like servicing endpoints before the sketch ends

      uint16_t magic_key_pos = MAGIC_KEY_POS;

// If we don't use the new RAMEND directly, check manually if we have a newer bootloader.
// This is used to keep compatible with the old leonardo bootloaders.
// You are still able to set the magic key position manually to RAMEND-1 to save a few bytes for this check.
#if MAGIC_KEY_POS != (RAMEND-1)
      // For future boards save the key in the inproblematic RAMEND
      // Which is reserved for the main() return value (which will never return)
      if (_updatedLUFAbootloader) {
        // horray, we got a new bootloader!
        magic_key_pos = (RAMEND-1);
      }
#endif

      // We check DTR state to determine if host port is open (bit 0 of lineState).
      if (1200 == _usbLineInfo.dwDTERate && (_usbLineInfo.lineState & 0x01) == 0)
      {
#if MAGIC_KEY_POS != (RAMEND-1)
        // Backup ram value if its not a newer bootloader.
        // This should avoid memory corruption at least a bit, not fully
        if (magic_key_pos != (RAMEND-1)) {
          *(uint16_t *)(RAMEND-1) = *(uint16_t *)magic_key_pos;
        }
#endif
        // Store boot key
        *(uint16_t *)magic_key_pos = MAGIC_KEY;
        wdt_enable(WDTO_120MS);
      }
      else
      {
        // Most OSs do some intermediate steps when configuring ports and DTR can
        // twiggle more than once before stabilizing.
        // To avoid spurious resets we set the watchdog to 250ms and eventually
        // cancel if DTR goes back high.

        wdt_disable();
        wdt_reset();
#if MAGIC_KEY_POS != (RAMEND-1)
        // Restore backed up (old bootloader) magic key data
        if (magic_key_pos != (RAMEND-1)) {
          *(uint16_t *)magic_key_pos = *(uint16_t *)(RAMEND-1);
        } else
#endif
        {
        // Clean up RAMEND key
          *(uint16_t *)magic_key_pos = 0x0000;
        }
      }
    }
    return true;
  }
  return false;
}


void Serial_::begin(unsigned long /* baud_count */)
{
  peek_buffer = -1;
}

void Serial_::begin(unsigned long /* baud_count */, byte /* config */)
{
  peek_buffer = -1;
}

void Serial_::end(void)
{
}

int Serial_::available(void)
{
  if (peek_buffer >= 0) {
    return 1 + USB_Available(CDC_RX);
  }
  return USB_Available(CDC_RX);
}

int Serial_::peek(void)
{
  if (peek_buffer < 0)
    peek_buffer = USB_Recv(CDC_RX);
  return peek_buffer;
}

int Serial_::read(void)
{
  if (peek_buffer >= 0) {
    int c = peek_buffer;
    peek_buffer = -1;
    return c;
  }
  return USB_Recv(CDC_RX);
}

int Serial_::availableForWrite(void)
{
  return USB_SendSpace(CDC_TX);
}

void Serial_::flush(void)
{
  USB_Flush(CDC_TX);
}

size_t Serial_::write(uint8_t c)
{
  return write(&c, 1);
}

size_t Serial_::write(const uint8_t *buffer, size_t size)
{
  /* only try to send bytes if the high-level CDC connection itself 
   is open (not just the pipe) - the OS should set lineState when the port
   is opened and clear lineState when the port is closed.
   bytes sent before the user opens the connection or after
   the connection is closed are lost - just like with a UART. */
  
  // TODO - ZE - check behavior on different OSes and test what happens if an
  // open connection isn't broken cleanly (cable is yanked out, host dies
  // or locks up, or host virtual serial port hangs)
  if (_usbLineInfo.lineState > 0) {
    int r = USB_Send(CDC_TX,buffer,size);
    if (r > 0) {
      return r;
    } else {
      setWriteError();
      return 0;
    }
  }
  setWriteError();
  return 0;
}

// This operator is a convenient way for a sketch to check whether the
// port has actually been configured and opened by the host (as opposed
// to just being connected to the host).  It can be used, for example, in 
// setup() before printing to ensure that an application on the host is
// actually ready to receive and display the data.
// We add a short delay before returning to fix a bug observed by Federico
// where the port is configured (lineState != 0) but not quite opened.
Serial_::operator bool() {
  bool result = false;
  if (_usbLineInfo.lineState > 0) 
    result = true;
  delay(10);
  return result;
}

unsigned long Serial_::baud() {
  // Disable interrupts while reading a multi-byte value
  uint32_t baudrate;
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    baudrate =  _usbLineInfo.dwDTERate;
  }
  return baudrate;
}

uint8_t Serial_::stopbits() {
  return _usbLineInfo.bCharFormat;
}

uint8_t Serial_::paritytype() {
  return _usbLineInfo.bParityType;
}

uint8_t Serial_::numbits() {
  return _usbLineInfo.bDataBits;
}

bool Serial_::dtr() {
  return _usbLineInfo.lineState & 0x1;
}

bool Serial_::rts() {
  return _usbLineInfo.lineState & 0x2;
}

int32_t Serial_::readBreak() {
  int32_t ret;
  // Disable IRQs while reading and clearing breakValue to make
  // sure we don't overwrite a value just set by the ISR.
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
    ret = breakValue;
    breakValue = -1;
  }
  return ret;
}

Serial_ Serial;

#endif /* if defined(USBCON) */