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