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