drivers/usb/serial/ftdi_sio.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Driver definitions for the FTDI USB Single Port Serial Converter -
   4  * known as FTDI_SIO (Serial Input/Output application of the chipset)
   5  *
   6  * For USB vendor/product IDs (VID/PID), please see ftdi_sio_ids.h
   7  *
   8  *
   9  * The example I have is known as the USC-1000 which is available from
  10  * http://www.dse.co.nz - cat no XH4214 It looks similar to this:
  11  * http://www.dansdata.com/usbser.htm but I can't be sure There are other
  12  * USC-1000s which don't look like my device though so beware!
  13  *
  14  * The device is based on the FTDI FT8U100AX chip. It has a DB25 on one side,
  15  * USB on the other.
  16  *
  17  * Thanx to FTDI (http://www.ftdichip.com) for so kindly providing details
  18  * of the protocol required to talk to the device and ongoing assistence
  19  * during development.
  20  *
  21  * Bill Ryder - bryder@sgi.com formerly of Silicon Graphics, Inc.- wrote the
  22  * FTDI_SIO implementation.
  23  *
  24  */
  25
  26 /* Commands */
  27 #define FTDI_SIO_RESET                  0 /* Reset the port */
  28 #define FTDI_SIO_MODEM_CTRL             1 /* Set the modem control register */
  29 #define FTDI_SIO_SET_FLOW_CTRL          2 /* Set flow control register */
  30 #define FTDI_SIO_SET_BAUD_RATE          3 /* Set baud rate */
  31 #define FTDI_SIO_SET_DATA               4 /* Set the data characteristics of
  32                                              the port */
  33 #define FTDI_SIO_GET_MODEM_STATUS       5 /* Retrieve current value of modem
  34                                              status register */
  35 #define FTDI_SIO_SET_EVENT_CHAR         6 /* Set the event character */
  36 #define FTDI_SIO_SET_ERROR_CHAR         7 /* Set the error character */
  37 #define FTDI_SIO_SET_LATENCY_TIMER      9 /* Set the latency timer */
  38 #define FTDI_SIO_GET_LATENCY_TIMER      0x0a /* Get the latency timer */
  39 #define FTDI_SIO_SET_BITMODE            0x0b /* Set bitbang mode */
  40 #define FTDI_SIO_READ_PINS              0x0c /* Read immediate value of pins */
  41 #define FTDI_SIO_READ_EEPROM            0x90 /* Read EEPROM */
  42
  43 /* Interface indices for FT2232, FT2232H and FT4232H devices */
  44 #define INTERFACE_A             1
  45 #define INTERFACE_B             2
  46 #define INTERFACE_C             3
  47 #define INTERFACE_D             4
  48
  49
  50 /*
  51  *   BmRequestType:  1100 0000b
  52  *   bRequest:       FTDI_E2_READ
  53  *   wValue:         0
  54  *   wIndex:         Address of word to read
  55  *   wLength:        2
  56  *   Data:           Will return a word of data from E2Address
  57  *
  58  */
  59
  60 /* Port Identifier Table */
  61 #define PIT_DEFAULT             0 /* SIOA */
  62 #define PIT_SIOA                1 /* SIOA */
  63 /* The device this driver is tested with one has only one port */
  64 #define PIT_SIOB                2 /* SIOB */
  65 #define PIT_PARALLEL            3 /* Parallel */
  66
  67 /* FTDI_SIO_RESET */
  68 #define FTDI_SIO_RESET_REQUEST FTDI_SIO_RESET
  69 #define FTDI_SIO_RESET_REQUEST_TYPE 0x40
  70 #define FTDI_SIO_RESET_SIO 0
  71 #define FTDI_SIO_RESET_PURGE_RX 1
  72 #define FTDI_SIO_RESET_PURGE_TX 2
  73
  74 /*
  75  * BmRequestType:  0100 0000B
  76  * bRequest:       FTDI_SIO_RESET
  77  * wValue:         Control Value
  78  *                   0 = Reset SIO
  79  *                   1 = Purge RX buffer
  80  *                   2 = Purge TX buffer
  81  * wIndex:         Port
  82  * wLength:        0
  83  * Data:           None
  84  *
  85  * The Reset SIO command has this effect:
  86  *
  87  *    Sets flow control set to 'none'
  88  *    Event char = $0D
  89  *    Event trigger = disabled
  90  *    Purge RX buffer
  91  *    Purge TX buffer
  92  *    Clear DTR
  93  *    Clear RTS
  94  *    baud and data format not reset
  95  *
  96  * The Purge RX and TX buffer commands affect nothing except the buffers
  97  *
  98    */
  99
 100 /* FTDI_SIO_SET_BAUDRATE */
 101 #define FTDI_SIO_SET_BAUDRATE_REQUEST_TYPE 0x40
 102 #define FTDI_SIO_SET_BAUDRATE_REQUEST 3
 103
 104 /*
 105  * BmRequestType:  0100 0000B
 106  * bRequest:       FTDI_SIO_SET_BAUDRATE
 107  * wValue:         BaudDivisor value - see below
 108  * wIndex:         Port
 109  * wLength:        0
 110  * Data:           None
 111  * The BaudDivisor values are calculated as follows:
 112  * - BaseClock is either 12000000 or 48000000 depending on the device.
 113  *   FIXME: I wish I knew how to detect old chips to select proper base clock!
 114  * - BaudDivisor is a fixed point number encoded in a funny way.
 115  *   (--WRONG WAY OF THINKING--)
 116  *   BaudDivisor is a fixed point number encoded with following bit weighs:
 117  *   (-2)(-1)(13..0). It is a radical with a denominator of 4, so values
 118  *   end with 0.0 (00...), 0.25 (10...), 0.5 (01...), and 0.75 (11...).
 119  *   (--THE REALITY--)
 120  *   The both-bits-set has quite different meaning from 0.75 - the chip
 121  *   designers have decided it to mean 0.125 instead of 0.75.
 122  *   This info looked up in FTDI application note "FT8U232 DEVICES \ Data Rates
 123  *   and Flow Control Consideration for USB to RS232".
 124  * - BaudDivisor = (BaseClock / 16) / BaudRate, where the (=) operation should
 125  *   automagically re-encode the resulting value to take fractions into
 126  *   consideration.
 127  * As all values are integers, some bit twiddling is in order:
 128  *   BaudDivisor = (BaseClock / 16 / BaudRate) |
 129  *   (((BaseClock / 2 / BaudRate) & 4) ? 0x4000    // 0.5
 130  *    : ((BaseClock / 2 / BaudRate) & 2) ? 0x8000  // 0.25
 131  *    : ((BaseClock / 2 / BaudRate) & 1) ? 0xc000  // 0.125
 132  *    : 0)
 133  *
 134  * For the FT232BM, a 17th divisor bit was introduced to encode the multiples
 135  * of 0.125 missing from the FT8U232AM.  Bits 16 to 14 are coded as follows
 136  * (the first four codes are the same as for the FT8U232AM, where bit 16 is
 137  * always 0):
 138  *   000 - add .000 to divisor
 139  *   001 - add .500 to divisor
 140  *   010 - add .250 to divisor
 141  *   011 - add .125 to divisor
 142  *   100 - add .375 to divisor
 143  *   101 - add .625 to divisor
 144  *   110 - add .750 to divisor
 145  *   111 - add .875 to divisor
 146  * Bits 15 to 0 of the 17-bit divisor are placed in the urb value.  Bit 16 is
 147  * placed in bit 0 of the urb index.
 148  *
 149  * Note that there are a couple of special cases to support the highest baud
 150  * rates.  If the calculated divisor value is 1, this needs to be replaced with
 151  * 0.  Additionally for the FT232BM, if the calculated divisor value is 0x4001
 152  * (1.5), this needs to be replaced with 0x0001 (1) (but this divisor value is
 153  * not supported by the FT8U232AM).
 154  */
 155
 156 enum ftdi_chip_type {
 157         SIO = 1,
 158         FT8U232AM = 2,
 159         FT232BM = 3,
 160         FT2232C = 4,
 161         FT232RL = 5,
 162         FT2232H = 6,
 163         FT4232H = 7,
 164         FT232H  = 8,
 165         FTX     = 9,
 166 };
 167
 168 enum ftdi_sio_baudrate {
 169         ftdi_sio_b300 = 0,
 170         ftdi_sio_b600 = 1,
 171         ftdi_sio_b1200 = 2,
 172         ftdi_sio_b2400 = 3,
 173         ftdi_sio_b4800 = 4,
 174         ftdi_sio_b9600 = 5,
 175         ftdi_sio_b19200 = 6,
 176         ftdi_sio_b38400 = 7,
 177         ftdi_sio_b57600 = 8,
 178         ftdi_sio_b115200 = 9
 179 };
 180
 181 /*
 182  * The ftdi_8U232AM_xxMHz_byyy constants have been removed. The encoded divisor
 183  * values are calculated internally.
 184  */
 185 #define FTDI_SIO_SET_DATA_REQUEST       FTDI_SIO_SET_DATA
 186 #define FTDI_SIO_SET_DATA_REQUEST_TYPE  0x40
 187 #define FTDI_SIO_SET_DATA_PARITY_NONE   (0x0 << 8)
 188 #define FTDI_SIO_SET_DATA_PARITY_ODD    (0x1 << 8)
 189 #define FTDI_SIO_SET_DATA_PARITY_EVEN   (0x2 << 8)
 190 #define FTDI_SIO_SET_DATA_PARITY_MARK   (0x3 << 8)
 191 #define FTDI_SIO_SET_DATA_PARITY_SPACE  (0x4 << 8)
 192 #define FTDI_SIO_SET_DATA_STOP_BITS_1   (0x0 << 11)
 193 #define FTDI_SIO_SET_DATA_STOP_BITS_15  (0x1 << 11)
 194 #define FTDI_SIO_SET_DATA_STOP_BITS_2   (0x2 << 11)
 195 #define FTDI_SIO_SET_BREAK              (0x1 << 14)
 196 /* FTDI_SIO_SET_DATA */
 197
 198 /*
 199  * BmRequestType:  0100 0000B
 200  * bRequest:       FTDI_SIO_SET_DATA
 201  * wValue:         Data characteristics (see below)
 202  * wIndex:         Port
 203  * wLength:        0
 204  * Data:           No
 205  *
 206  * Data characteristics
 207  *
 208  *   B0..7   Number of data bits
 209  *   B8..10  Parity
 210  *           0 = None
 211  *           1 = Odd
 212  *           2 = Even
 213  *           3 = Mark
 214  *           4 = Space
 215  *   B11..13 Stop Bits
 216  *           0 = 1
 217  *           1 = 1.5
 218  *           2 = 2
 219  *   B14
 220  *           1 = TX ON (break)
 221  *           0 = TX OFF (normal state)
 222  *   B15 Reserved
 223  *
 224  */
 225
 226
 227
 228 /* FTDI_SIO_MODEM_CTRL */
 229 #define FTDI_SIO_SET_MODEM_CTRL_REQUEST_TYPE 0x40
 230 #define FTDI_SIO_SET_MODEM_CTRL_REQUEST FTDI_SIO_MODEM_CTRL
 231
 232 /*
 233  * BmRequestType:   0100 0000B
 234  * bRequest:        FTDI_SIO_MODEM_CTRL
 235  * wValue:          ControlValue (see below)
 236  * wIndex:          Port
 237  * wLength:         0
 238  * Data:            None
 239  *
 240  * NOTE: If the device is in RTS/CTS flow control, the RTS set by this
 241  * command will be IGNORED without an error being returned
 242  * Also - you can not set DTR and RTS with one control message
 243  */
 244
 245 #define FTDI_SIO_SET_DTR_MASK 0x1
 246 #define FTDI_SIO_SET_DTR_HIGH ((FTDI_SIO_SET_DTR_MASK  << 8) | 1)
 247 #define FTDI_SIO_SET_DTR_LOW  ((FTDI_SIO_SET_DTR_MASK  << 8) | 0)
 248 #define FTDI_SIO_SET_RTS_MASK 0x2
 249 #define FTDI_SIO_SET_RTS_HIGH ((FTDI_SIO_SET_RTS_MASK << 8) | 2)
 250 #define FTDI_SIO_SET_RTS_LOW  ((FTDI_SIO_SET_RTS_MASK << 8) | 0)
 251
 252 /*
 253  * ControlValue
 254  * B0    DTR state
 255  *          0 = reset
 256  *          1 = set
 257  * B1    RTS state
 258  *          0 = reset
 259  *          1 = set
 260  * B2..7 Reserved
 261  * B8    DTR state enable
 262  *          0 = ignore
 263  *          1 = use DTR state
 264  * B9    RTS state enable
 265  *          0 = ignore
 266  *          1 = use RTS state
 267  * B10..15 Reserved
 268  */
 269
 270 /* FTDI_SIO_SET_FLOW_CTRL */
 271 #define FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE 0x40
 272 #define FTDI_SIO_SET_FLOW_CTRL_REQUEST FTDI_SIO_SET_FLOW_CTRL
 273 #define FTDI_SIO_DISABLE_FLOW_CTRL 0x0
 274 #define FTDI_SIO_RTS_CTS_HS (0x1 << 8)
 275 #define FTDI_SIO_DTR_DSR_HS (0x2 << 8)
 276 #define FTDI_SIO_XON_XOFF_HS (0x4 << 8)
 277 /*
 278  *   BmRequestType:  0100 0000b
 279  *   bRequest:       FTDI_SIO_SET_FLOW_CTRL
 280  *   wValue:         Xoff/Xon
 281  *   wIndex:         Protocol/Port - hIndex is protocol / lIndex is port
 282  *   wLength:        0
 283  *   Data:           None
 284  *
 285  * hIndex protocol is:
 286  *   B0 Output handshaking using RTS/CTS
 287  *       0 = disabled
 288  *       1 = enabled
 289  *   B1 Output handshaking using DTR/DSR
 290  *       0 = disabled
 291  *       1 = enabled
 292  *   B2 Xon/Xoff handshaking
 293  *       0 = disabled
 294  *       1 = enabled
 295  *
 296  * A value of zero in the hIndex field disables handshaking
 297  *
 298  * If Xon/Xoff handshaking is specified, the hValue field should contain the
 299  * XOFF character and the lValue field contains the XON character.
 300  */
 301
 302 /*
 303  * FTDI_SIO_GET_LATENCY_TIMER
 304  *
 305  * Set the timeout interval. The FTDI collects data from the
 306  * device, transmitting it to the host when either A) 62 bytes are
 307  * received, or B) the timeout interval has elapsed and the buffer
 308  * contains at least 1 byte.  Setting this value to a small number
 309  * can dramatically improve performance for applications which send
 310  * small packets, since the default value is 16ms.
 311  */
 312 #define  FTDI_SIO_GET_LATENCY_TIMER_REQUEST FTDI_SIO_GET_LATENCY_TIMER
 313 #define  FTDI_SIO_GET_LATENCY_TIMER_REQUEST_TYPE 0xC0
 314
 315 /*
 316  *  BmRequestType:   1100 0000b
 317  *  bRequest:        FTDI_SIO_GET_LATENCY_TIMER
 318  *  wValue:          0
 319  *  wIndex:          Port
 320  *  wLength:         0
 321  *  Data:            latency (on return)
 322  */
 323
 324 /*
 325  * FTDI_SIO_SET_LATENCY_TIMER
 326  *
 327  * Set the timeout interval. The FTDI collects data from the
 328  * device, transmitting it to the host when either A) 62 bytes are
 329  * received, or B) the timeout interval has elapsed and the buffer
 330  * contains at least 1 byte.  Setting this value to a small number
 331  * can dramatically improve performance for applications which send
 332  * small packets, since the default value is 16ms.
 333  */
 334 #define  FTDI_SIO_SET_LATENCY_TIMER_REQUEST FTDI_SIO_SET_LATENCY_TIMER
 335 #define  FTDI_SIO_SET_LATENCY_TIMER_REQUEST_TYPE 0x40
 336
 337 /*
 338  *  BmRequestType:   0100 0000b
 339  *  bRequest:        FTDI_SIO_SET_LATENCY_TIMER
 340  *  wValue:          Latency (milliseconds)
 341  *  wIndex:          Port
 342  *  wLength:         0
 343  *  Data:            None
 344  *
 345  * wValue:
 346  *   B0..7   Latency timer
 347  *   B8..15  0
 348  *
 349  */
 350
 351 /*
 352  * FTDI_SIO_SET_EVENT_CHAR
 353  *
 354  * Set the special event character for the specified communications port.
 355  * If the device sees this character it will immediately return the
 356  * data read so far - rather than wait 40ms or until 62 bytes are read
 357  * which is what normally happens.
 358  */
 359
 360
 361 #define  FTDI_SIO_SET_EVENT_CHAR_REQUEST FTDI_SIO_SET_EVENT_CHAR
 362 #define  FTDI_SIO_SET_EVENT_CHAR_REQUEST_TYPE 0x40
 363
 364
 365 /*
 366  *  BmRequestType:   0100 0000b
 367  *  bRequest:        FTDI_SIO_SET_EVENT_CHAR
 368  *  wValue:          EventChar
 369  *  wIndex:          Port
 370  *  wLength:         0
 371  *  Data:            None
 372  *
 373  * wValue:
 374  *   B0..7   Event Character
 375  *   B8      Event Character Processing
 376  *             0 = disabled
 377  *             1 = enabled
 378  *   B9..15  Reserved
 379  *
 380  */
 381
 382 /* FTDI_SIO_SET_ERROR_CHAR */
 383
 384 /*
 385  * Set the parity error replacement character for the specified communications
 386  * port
 387  */
 388
 389 /*
 390  *  BmRequestType:  0100 0000b
 391  *  bRequest:       FTDI_SIO_SET_EVENT_CHAR
 392  *  wValue:         Error Char
 393  *  wIndex:         Port
 394  *  wLength:        0
 395  *  Data:           None
 396  *
 397  *Error Char
 398  *  B0..7  Error Character
 399  *  B8     Error Character Processing
 400  *           0 = disabled
 401  *           1 = enabled
 402  *  B9..15 Reserved
 403  *
 404  */
 405
 406 /* FTDI_SIO_GET_MODEM_STATUS */
 407 /* Retrieve the current value of the modem status register */
 408
 409 #define FTDI_SIO_GET_MODEM_STATUS_REQUEST_TYPE 0xc0
 410 #define FTDI_SIO_GET_MODEM_STATUS_REQUEST FTDI_SIO_GET_MODEM_STATUS
 411 #define FTDI_SIO_CTS_MASK 0x10
 412 #define FTDI_SIO_DSR_MASK 0x20
 413 #define FTDI_SIO_RI_MASK  0x40
 414 #define FTDI_SIO_RLSD_MASK 0x80
 415 /*
 416  *   BmRequestType:   1100 0000b
 417  *   bRequest:        FTDI_SIO_GET_MODEM_STATUS
 418  *   wValue:          zero
 419  *   wIndex:          Port
 420  *   wLength:         1
 421  *   Data:            Status
 422  *
 423  * One byte of data is returned
 424  * B0..3 0
 425  * B4    CTS
 426  *         0 = inactive
 427  *         1 = active
 428  * B5    DSR
 429  *         0 = inactive
 430  *         1 = active
 431  * B6    Ring Indicator (RI)
 432  *         0 = inactive
 433  *         1 = active
 434  * B7    Receive Line Signal Detect (RLSD)
 435  *         0 = inactive
 436  *         1 = active
 437  */
 438
 439 /* FTDI_SIO_SET_BITMODE */
 440 #define FTDI_SIO_SET_BITMODE_REQUEST_TYPE 0x40
 441 #define FTDI_SIO_SET_BITMODE_REQUEST FTDI_SIO_SET_BITMODE
 442
 443 /* Possible bitmodes for FTDI_SIO_SET_BITMODE_REQUEST */
 444 #define FTDI_SIO_BITMODE_RESET          0x00
 445 #define FTDI_SIO_BITMODE_CBUS           0x20
 446
 447 /* FTDI_SIO_READ_PINS */
 448 #define FTDI_SIO_READ_PINS_REQUEST_TYPE 0xc0
 449 #define FTDI_SIO_READ_PINS_REQUEST FTDI_SIO_READ_PINS
 450
 451 /*
 452  * FTDI_SIO_READ_EEPROM
 453  *
 454  * EEPROM format found in FTDI AN_201, "FT-X MTP memory Configuration",
 455  * http://www.ftdichip.com/Support/Documents/AppNotes/AN_201_FT-X%20MTP%20Memory%20Configuration.pdf
 456  */
 457 #define FTDI_SIO_READ_EEPROM_REQUEST_TYPE 0xc0
 458 #define FTDI_SIO_READ_EEPROM_REQUEST FTDI_SIO_READ_EEPROM
 459
 460 #define FTDI_FTX_CBUS_MUX_GPIO          0x8
 461 #define FTDI_FT232R_CBUS_MUX_GPIO       0xa
 462
 463
 464 /* Descriptors returned by the device
 465  *
 466  *  Device Descriptor
 467  *
 468  * Offset       Field           Size    Value   Description
 469  * 0    bLength         1       0x12    Size of descriptor in bytes
 470  * 1    bDescriptorType 1       0x01    DEVICE Descriptor Type
 471  * 2    bcdUSB          2       0x0110  USB Spec Release Number
 472  * 4    bDeviceClass    1       0x00    Class Code
 473  * 5    bDeviceSubClass 1       0x00    SubClass Code
 474  * 6    bDeviceProtocol 1       0x00    Protocol Code
 475  * 7    bMaxPacketSize0 1       0x08    Maximum packet size for endpoint 0
 476  * 8    idVendor        2       0x0403  Vendor ID
 477  * 10   idProduct       2       0x8372  Product ID (FTDI_SIO_PID)
 478  * 12   bcdDevice       2       0x0001  Device release number
 479  * 14   iManufacturer   1       0x01    Index of man. string desc
 480  * 15   iProduct        1       0x02    Index of prod string desc
 481  * 16   iSerialNumber   1       0x02    Index of serial nmr string desc
 482  * 17   bNumConfigurations 1    0x01    Number of possible configurations
 483  *
 484  * Configuration Descriptor
 485  *
 486  * Offset       Field                   Size    Value
 487  * 0    bLength                 1       0x09    Size of descriptor in bytes
 488  * 1    bDescriptorType         1       0x02    CONFIGURATION Descriptor Type
 489  * 2    wTotalLength            2       0x0020  Total length of data
 490  * 4    bNumInterfaces          1       0x01    Number of interfaces supported
 491  * 5    bConfigurationValue     1       0x01    Argument for SetCOnfiguration() req
 492  * 6    iConfiguration          1       0x02    Index of config string descriptor
 493  * 7    bmAttributes            1       0x20    Config characteristics Remote Wakeup
 494  * 8    MaxPower                1       0x1E    Max power consumption
 495  *
 496  * Interface Descriptor
 497  *
 498  * Offset       Field                   Size    Value
 499  * 0    bLength                 1       0x09    Size of descriptor in bytes
 500  * 1    bDescriptorType         1       0x04    INTERFACE Descriptor Type
 501  * 2    bInterfaceNumber        1       0x00    Number of interface
 502  * 3    bAlternateSetting       1       0x00    Value used to select alternate
 503  * 4    bNumEndpoints           1       0x02    Number of endpoints
 504  * 5    bInterfaceClass         1       0xFF    Class Code
 505  * 6    bInterfaceSubClass      1       0xFF    Subclass Code
 506  * 7    bInterfaceProtocol      1       0xFF    Protocol Code
 507  * 8    iInterface              1       0x02    Index of interface string description
 508  *
 509  * IN Endpoint Descriptor
 510  *
 511  * Offset       Field                   Size    Value
 512  * 0    bLength                 1       0x07    Size of descriptor in bytes
 513  * 1    bDescriptorType         1       0x05    ENDPOINT descriptor type
 514  * 2    bEndpointAddress        1       0x82    Address of endpoint
 515  * 3    bmAttributes            1       0x02    Endpoint attributes - Bulk
 516  * 4    bNumEndpoints           2       0x0040  maximum packet size
 517  * 5    bInterval               1       0x00    Interval for polling endpoint
 518  *
 519  * OUT Endpoint Descriptor
 520  *
 521  * Offset       Field                   Size    Value
 522  * 0    bLength                 1       0x07    Size of descriptor in bytes
 523  * 1    bDescriptorType         1       0x05    ENDPOINT descriptor type
 524  * 2    bEndpointAddress        1       0x02    Address of endpoint
 525  * 3    bmAttributes            1       0x02    Endpoint attributes - Bulk
 526  * 4    bNumEndpoints           2       0x0040  maximum packet size
 527  * 5    bInterval               1       0x00    Interval for polling endpoint
 528  *
 529  * DATA FORMAT
 530  *
 531  * IN Endpoint
 532  *
 533  * The device reserves the first two bytes of data on this endpoint to contain
 534  * the current values of the modem and line status registers. In the absence of
 535  * data, the device generates a message consisting of these two status bytes
 536  * every 40 ms
 537  *
 538  * Byte 0: Modem Status
 539  *
 540  * Offset       Description
 541  * B0   Reserved - must be 1
 542  * B1   Reserved - must be 0
 543  * B2   Reserved - must be 0
 544  * B3   Reserved - must be 0
 545  * B4   Clear to Send (CTS)
 546  * B5   Data Set Ready (DSR)
 547  * B6   Ring Indicator (RI)
 548  * B7   Receive Line Signal Detect (RLSD)
 549  *
 550  * Byte 1: Line Status
 551  *
 552  * Offset       Description
 553  * B0   Data Ready (DR)
 554  * B1   Overrun Error (OE)
 555  * B2   Parity Error (PE)
 556  * B3   Framing Error (FE)
 557  * B4   Break Interrupt (BI)
 558  * B5   Transmitter Holding Register (THRE)
 559  * B6   Transmitter Empty (TEMT)
 560  * B7   Error in RCVR FIFO
 561  *
 562  */
 563 #define FTDI_RS0_CTS    (1 << 4)
 564 #define FTDI_RS0_DSR    (1 << 5)
 565 #define FTDI_RS0_RI     (1 << 6)
 566 #define FTDI_RS0_RLSD   (1 << 7)
 567
 568 #define FTDI_RS_DR      1
 569 #define FTDI_RS_OE      (1<<1)
 570 #define FTDI_RS_PE      (1<<2)
 571 #define FTDI_RS_FE      (1<<3)
 572 #define FTDI_RS_BI      (1<<4)
 573 #define FTDI_RS_THRE    (1<<5)
 574 #define FTDI_RS_TEMT    (1<<6)
 575 #define FTDI_RS_FIFO    (1<<7)
 576
 577 /*
 578  * OUT Endpoint
 579  *
 580  * This device reserves the first bytes of data on this endpoint contain the
 581  * length and port identifier of the message. For the FTDI USB Serial converter
 582  * the port identifier is always 1.
 583  *
 584  * Byte 0: Line Status
 585  *
 586  * Offset       Description
 587  * B0   Reserved - must be 1
 588  * B1   Reserved - must be 0
 589  * B2..7        Length of message - (not including Byte 0)
 590  *
 591  */