drivers/usb/serial/safe_serial.c

   1 /*
   2  * Safe Encapsulated USB Serial Driver
   3  *
   4  *      Copyright (C) 2001 Lineo
   5  *      Copyright (C) 2001 Hewlett-Packard
   6  *
   7  *      This program is free software; you can redistribute it and/or modify
   8  *      it under the terms of the GNU General Public License as published by
   9  *      the Free Software Foundation; either version 2 of the License, or
  10  *      (at your option) any later version.
  11  *
  12  * By:
  13  *      Stuart Lynne <sl@lineo.com>, Tom Rushworth <tbr@lineo.com>
  14  */
  15
  16 /*
  17  * The encapsultaion is designed to overcome difficulties with some USB
  18  * hardware.
  19  *
  20  * While the USB protocol has a CRC over the data while in transit, i.e. while
  21  * being carried over the bus, there is no end to end protection. If the
  22  * hardware has any problems getting the data into or out of the USB transmit
  23  * and receive FIFO's then data can be lost.
  24  *
  25  * This protocol adds a two byte trailer to each USB packet to specify the
  26  * number of bytes of valid data and a 10 bit CRC that will allow the receiver
  27  * to verify that the entire USB packet was received without error.
  28  *
  29  * Because in this case the sender and receiver are the class and function
  30  * drivers there is now end to end protection.
  31  *
  32  * There is an additional option that can be used to force all transmitted
  33  * packets to be padded to the maximum packet size. This provides a work
  34  * around for some devices which have problems with small USB packets.
  35  *
  36  * Assuming a packetsize of N:
  37  *
  38  *      0..N-2  data and optional padding
  39  *
  40  *      N-2     bits 7-2 - number of bytes of valid data
  41  *              bits 1-0 top two bits of 10 bit CRC
  42  *      N-1     bottom 8 bits of 10 bit CRC
  43  *
  44  *
  45  *      | Data Length       | 10 bit CRC                                |
  46  *      + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 | 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 +
  47  *
  48  * The 10 bit CRC is computed across the sent data, followed by the trailer
  49  * with the length set and the CRC set to zero. The CRC is then OR'd into
  50  * the trailer.
  51  *
  52  * When received a 10 bit CRC is computed over the entire frame including
  53  * the trailer and should be equal to zero.
  54  *
  55  * Two module parameters are used to control the encapsulation, if both are
  56  * turned of the module works as a simple serial device with NO
  57  * encapsulation.
  58  *
  59  * See linux/drivers/usbd/serial_fd for a device function driver
  60  * implementation of this.
  61  *
  62  */
  63
  64
  65 #include <linux/kernel.h>
  66 #include <linux/errno.h>
  67 #include <linux/init.h>
  68 #include <linux/slab.h>
  69 #include <linux/tty.h>
  70 #include <linux/tty_driver.h>
  71 #include <linux/tty_flip.h>
  72 #include <linux/module.h>
  73 #include <linux/spinlock.h>
  74 #include <linux/uaccess.h>
  75 #include <linux/usb.h>
  76 #include <linux/usb/serial.h>
  77
  78
  79 #ifndef CONFIG_USB_SERIAL_SAFE_PADDED
  80 #define CONFIG_USB_SERIAL_SAFE_PADDED 0
  81 #endif
  82
  83 static int debug;
  84 static int safe = 1;
  85 static int padded = CONFIG_USB_SERIAL_SAFE_PADDED;
  86
  87 #define DRIVER_VERSION "v0.0b"
  88 #define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com"
  89 #define DRIVER_DESC "USB Safe Encapsulated Serial"
  90
  91 MODULE_AUTHOR(DRIVER_AUTHOR);
  92 MODULE_DESCRIPTION(DRIVER_DESC);
  93 MODULE_LICENSE("GPL");
  94
  95 static __u16 vendor;            /* no default */
  96 static __u16 product;           /* no default */
  97 module_param(vendor, ushort, 0);
  98 MODULE_PARM_DESC(vendor, "User specified USB idVendor (required)");
  99 module_param(product, ushort, 0);
 100 MODULE_PARM_DESC(product, "User specified USB idProduct (required)");
 101
 102 module_param(debug, bool, S_IRUGO | S_IWUSR);
 103 MODULE_PARM_DESC(debug, "Debug enabled or not");
 104
 105 module_param(safe, bool, 0);
 106 MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
 107
 108 module_param(padded, bool, 0);
 109 MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
 110
 111 #define CDC_DEVICE_CLASS                        0x02
 112
 113 #define CDC_INTERFACE_CLASS                     0x02
 114 #define CDC_INTERFACE_SUBCLASS                  0x06
 115
 116 #define LINEO_INTERFACE_CLASS                   0xff
 117
 118 #define LINEO_INTERFACE_SUBCLASS_SAFENET        0x01
 119 #define LINEO_SAFENET_CRC                       0x01
 120 #define LINEO_SAFENET_CRC_PADDED                0x02
 121
 122 #define LINEO_INTERFACE_SUBCLASS_SAFESERIAL     0x02
 123 #define LINEO_SAFESERIAL_CRC                    0x01
 124 #define LINEO_SAFESERIAL_CRC_PADDED             0x02
 125
 126
 127 #define MY_USB_DEVICE(vend, prod, dc, ic, isc) \
 128         .match_flags = USB_DEVICE_ID_MATCH_DEVICE | \
 129                        USB_DEVICE_ID_MATCH_DEV_CLASS | \
 130                        USB_DEVICE_ID_MATCH_INT_CLASS | \
 131                        USB_DEVICE_ID_MATCH_INT_SUBCLASS, \
 132         .idVendor = (vend), \
 133         .idProduct = (prod),\
 134         .bDeviceClass = (dc),\
 135         .bInterfaceClass = (ic), \
 136         .bInterfaceSubClass = (isc),
 137
 138 static struct usb_device_id id_table[] = {
 139         {MY_USB_DEVICE(0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},   /* Itsy */
 140         {MY_USB_DEVICE(0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},   /* Calypso */
 141         {MY_USB_DEVICE(0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},   /* Iris */
 142         {MY_USB_DEVICE(0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},   /* Collie */
 143         {MY_USB_DEVICE(0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},   /* Collie */
 144         {MY_USB_DEVICE(0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},   /* Collie */
 145         {MY_USB_DEVICE(0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},   /* Sharp tmp */
 146         /* extra null entry for module vendor/produc parameters */
 147         {MY_USB_DEVICE(0, 0, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},
 148         {}                      /* terminating entry  */
 149 };
 150
 151 MODULE_DEVICE_TABLE(usb, id_table);
 152
 153 static struct usb_driver safe_driver = {
 154         .name =         "safe_serial",
 155         .probe =        usb_serial_probe,
 156         .disconnect =   usb_serial_disconnect,
 157         .id_table =     id_table,
 158         .no_dynamic_id =        1,
 159 };
 160
 161 static const __u16 crc10_table[256] = {
 162         0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff,
 163         0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
 164         0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce,
 165         0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
 166         0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d,
 167         0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
 168         0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac,
 169         0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
 170         0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b,
 171         0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
 172         0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a,
 173         0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
 174         0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259,
 175         0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
 176         0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268,
 177         0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
 178         0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377,
 179         0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
 180         0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346,
 181         0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
 182         0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315,
 183         0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
 184         0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324,
 185         0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
 186         0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3,
 187         0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
 188         0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382,
 189         0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
 190         0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1,
 191         0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
 192         0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0,
 193         0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
 194 };
 195
 196 #define CRC10_INITFCS     0x000 /* Initial FCS value */
 197 #define CRC10_GOODFCS     0x000 /* Good final FCS value */
 198 #define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
 199
 200 /**
 201  * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
 202  * @sp: pointer to buffer
 203  * @len: number of bytes
 204  * @fcs: starting FCS
 205  *
 206  * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
 207  * new 10 bit FCS.
 208  */
 209 static __u16 __inline__ fcs_compute10(unsigned char *sp, int len, __u16 fcs)
 210 {
 211         for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++));
 212         return fcs;
 213 }
 214
 215 static void safe_read_bulk_callback(struct urb *urb)
 216 {
 217         struct usb_serial_port *port =  urb->context;
 218         unsigned char *data = urb->transfer_buffer;
 219         unsigned char length = urb->actual_length;
 220         int result;
 221         int status = urb->status;
 222
 223         dbg("%s", __func__);
 224
 225         if (status) {
 226                 dbg("%s - nonzero read bulk status received: %d",
 227                     __func__, status);
 228                 return;
 229         }
 230
 231         dbg("safe_read_bulk_callback length: %d",
 232                                         port->read_urb->actual_length);
 233 #ifdef ECHO_RCV
 234         {
 235                 int i;
 236                 unsigned char *cp = port->read_urb->transfer_buffer;
 237                 for (i = 0; i < port->read_urb->actual_length; i++) {
 238                         if ((i % 32) == 0)
 239                                 printk("\nru[%02x] ", i);
 240                         printk("%02x ", *cp++);
 241                 }
 242                 printk("\n");
 243         }
 244 #endif
 245         if (safe) {
 246                 __u16 fcs;
 247                 fcs = fcs_compute10(data, length, CRC10_INITFCS);
 248                 if (!fcs) {
 249                         int actual_length = data[length - 2] >> 2;
 250                         if (actual_length <= (length - 2)) {
 251                                 info("%s - actual: %d", __func__,
 252                                                         actual_length);
 253                                 tty_insert_flip_string(port->port.tty,
 254                                                         data, actual_length);
 255                                 tty_flip_buffer_push(port->port.tty);
 256                         } else {
 257                                 err("%s - inconsistent lengths %d:%d",
 258                                         __func__, actual_length, length);
 259                         }
 260                 } else {
 261                         err("%s - bad CRC %x", __func__, fcs);
 262                 }
 263         } else {
 264                 tty_insert_flip_string(port->port.tty, data, length);
 265                 tty_flip_buffer_push(port->port.tty);
 266         }
 267
 268         /* Continue trying to always read  */
 269         usb_fill_bulk_urb(urb, port->serial->dev,
 270                         usb_rcvbulkpipe(port->serial->dev,
 271                                         port->bulk_in_endpointAddress),
 272                         urb->transfer_buffer, urb->transfer_buffer_length,
 273                         safe_read_bulk_callback, port);
 274
 275         result = usb_submit_urb(urb, GFP_ATOMIC);
 276         if (result)
 277                 err("%s - failed resubmitting read urb, error %d",
 278                                                         __func__, result);
 279                 /* FIXME: Need a mechanism to retry later if this happens */
 280 }
 281
 282 static int safe_write(struct tty_struct *tty, struct usb_serial_port *port,
 283                                         const unsigned char *buf, int count)
 284 {
 285         unsigned char *data;
 286         int result;
 287         int i;
 288         int packet_length;
 289
 290         dbg("safe_write port: %p %d urb: %p count: %d",
 291                                 port, port->number, port->write_urb, count);
 292
 293         if (!port->write_urb) {
 294                 dbg("%s - write urb NULL", __func__);
 295                 return 0;
 296         }
 297
 298         dbg("safe_write write_urb: %d transfer_buffer_length",
 299              port->write_urb->transfer_buffer_length);
 300
 301         if (!port->write_urb->transfer_buffer_length) {
 302                 dbg("%s - write urb transfer_buffer_length zero", __func__);
 303                 return 0;
 304         }
 305         if (count == 0) {
 306                 dbg("%s - write request of 0 bytes", __func__);
 307                 return 0;
 308         }
 309         spin_lock_bh(&port->lock);
 310         if (port->write_urb_busy) {
 311                 spin_unlock_bh(&port->lock);
 312                 dbg("%s - already writing", __func__);
 313                 return 0;
 314         }
 315         port->write_urb_busy = 1;
 316         spin_unlock_bh(&port->lock);
 317
 318         packet_length = port->bulk_out_size;    /* get max packetsize */
 319
 320         i = packet_length - (safe ? 2 : 0);     /* get bytes to send */
 321         count = (count > i) ? i : count;
 322
 323
 324         /* get the data into the transfer buffer */
 325         data = port->write_urb->transfer_buffer;
 326         memset(data, '0', packet_length);
 327
 328         memcpy(data, buf, count);
 329
 330         if (safe) {
 331                 __u16 fcs;
 332
 333                 /* pad if necessary */
 334                 if (!padded)
 335                         packet_length = count + 2;
 336                 /* set count */
 337                 data[packet_length - 2] = count << 2;
 338                 data[packet_length - 1] = 0;
 339
 340                 /* compute fcs and insert into trailer */
 341                 fcs = fcs_compute10(data, packet_length, CRC10_INITFCS);
 342                 data[packet_length - 2] |= fcs >> 8;
 343                 data[packet_length - 1] |= fcs & 0xff;
 344
 345                 /* set length to send */
 346                 port->write_urb->transfer_buffer_length = packet_length;
 347         } else {
 348                 port->write_urb->transfer_buffer_length = count;
 349         }
 350
 351         usb_serial_debug_data(debug, &port->dev, __func__, count,
 352                                         port->write_urb->transfer_buffer);
 353 #ifdef ECHO_TX
 354         {
 355                 int i;
 356                 unsigned char *cp = port->write_urb->transfer_buffer;
 357                 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) {
 358                         if ((i % 32) == 0)
 359                                 printk("\nsu[%02x] ", i);
 360                         printk("%02x ", *cp++);
 361                 }
 362                 printk("\n");
 363         }
 364 #endif
 365         port->write_urb->dev = port->serial->dev;
 366         result = usb_submit_urb(port->write_urb, GFP_KERNEL);
 367         if (result) {
 368                 port->write_urb_busy = 0;
 369                 err("%s - failed submitting write urb, error %d",
 370                                                         __func__, result);
 371                 return 0;
 372         }
 373         dbg("%s urb: %p submitted", __func__, port->write_urb);
 374
 375         return count;
 376 }
 377
 378 static int safe_write_room(struct tty_struct *tty)
 379 {
 380         struct usb_serial_port *port = tty->driver_data;
 381         int room = 0;           /* Default: no room */
 382         unsigned long flags;
 383
 384         dbg("%s", __func__);
 385
 386         spin_lock_irqsave(&port->lock, flags);
 387         if (port->write_urb_busy)
 388                 room = port->bulk_out_size - (safe ? 2 : 0);
 389         spin_unlock_irqrestore(&port->lock, flags);
 390
 391         if (room)
 392                 dbg("safe_write_room returns %d", room);
 393         return room;
 394 }
 395
 396 static int safe_startup(struct usb_serial *serial)
 397 {
 398         switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) {
 399         case LINEO_SAFESERIAL_CRC:
 400                 break;
 401         case LINEO_SAFESERIAL_CRC_PADDED:
 402                 padded = 1;
 403                 break;
 404         default:
 405                 return -EINVAL;
 406         }
 407         return 0;
 408 }
 409
 410 static struct usb_serial_driver safe_device = {
 411         .driver = {
 412                 .owner =        THIS_MODULE,
 413                 .name =         "safe_serial",
 414         },
 415         .id_table =             id_table,
 416         .usb_driver =           &safe_driver,
 417         .num_ports =            1,
 418         .write =                safe_write,
 419         .write_room =           safe_write_room,
 420         .read_bulk_callback =   safe_read_bulk_callback,
 421         .attach =               safe_startup,
 422 };
 423
 424 static int __init safe_init(void)
 425 {
 426         int i, retval;
 427
 428         info(DRIVER_VERSION " " DRIVER_AUTHOR);
 429         info(DRIVER_DESC);
 430         info("vendor: %x product: %x safe: %d padded: %d\n",
 431                                         vendor, product, safe, padded);
 432
 433         /* if we have vendor / product parameters patch them into id list */
 434         if (vendor || product) {
 435                 info("vendor: %x product: %x\n", vendor, product);
 436
 437                 for (i = 0; i < ARRAY_SIZE(id_table); i++) {
 438                         if (!id_table[i].idVendor && !id_table[i].idProduct) {
 439                                 id_table[i].idVendor = vendor;
 440                                 id_table[i].idProduct = product;
 441                                 break;
 442                         }
 443                 }
 444         }
 445
 446         retval = usb_serial_register(&safe_device);
 447         if (retval)
 448                 goto failed_usb_serial_register;
 449         retval = usb_register(&safe_driver);
 450         if (retval)
 451                 goto failed_usb_register;
 452
 453         return 0;
 454 failed_usb_register:
 455         usb_serial_deregister(&safe_device);
 456 failed_usb_serial_register:
 457         return retval;
 458 }
 459
 460 static void __exit safe_exit(void)
 461 {
 462         usb_deregister(&safe_driver);
 463         usb_serial_deregister(&safe_device);
 464 }
 465
 466 module_init(safe_init);
 467 module_exit(safe_exit);