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_SERIAL_SAFE_PADDED
  78 #define CONFIG_USB_SERIAL_SAFE_PADDED 0
  79 #endif
  80
  81 static int debug;
  82 static int safe = 1;
  83 static int padded = CONFIG_USB_SERIAL_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)
 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         int status = urb->status;
 215
 216         dbg ("%s", __FUNCTION__);
 217
 218         if (status) {
 219                 dbg("%s - nonzero read bulk status received: %d",
 220                     __FUNCTION__, status);
 221                 return;
 222         }
 223
 224         dbg ("safe_read_bulk_callback length: %d", port->read_urb->actual_length);
 225 #ifdef ECHO_RCV
 226         {
 227                 int i;
 228                 unsigned char *cp = port->read_urb->transfer_buffer;
 229                 for (i = 0; i < port->read_urb->actual_length; i++) {
 230                         if ((i % 32) == 0) {
 231                                 printk ("\nru[%02x] ", i);
 232                         }
 233                         printk ("%02x ", *cp++);
 234                 }
 235                 printk ("\n");
 236         }
 237 #endif
 238         if (safe) {
 239                 __u16 fcs;
 240                 if (!(fcs = fcs_compute10 (data, length, CRC10_INITFCS))) {
 241
 242                         int actual_length = data[length - 2] >> 2;
 243
 244                         if (actual_length <= (length - 2)) {
 245
 246                                 info ("%s - actual: %d", __FUNCTION__, actual_length);
 247
 248                                 for (i = 0; i < actual_length; i++) {
 249                                         tty_insert_flip_char (port->tty, data[i], 0);
 250                                 }
 251                                 tty_flip_buffer_push (port->tty);
 252                         } else {
 253                                 err ("%s - inconsistent lengths %d:%d", __FUNCTION__,
 254                                      actual_length, length);
 255                         }
 256                 } else {
 257                         err ("%s - bad CRC %x", __FUNCTION__, fcs);
 258                 }
 259         } else {
 260                 for (i = 0; i < length; i++) {
 261                         tty_insert_flip_char (port->tty, data[i], 0);
 262                 }
 263                 tty_flip_buffer_push (port->tty);
 264         }
 265
 266         /* Continue trying to always read  */
 267         usb_fill_bulk_urb (urb, port->serial->dev,
 268                        usb_rcvbulkpipe (port->serial->dev, port->bulk_in_endpointAddress),
 269                        urb->transfer_buffer, urb->transfer_buffer_length,
 270                        safe_read_bulk_callback, port);
 271
 272         if ((result = usb_submit_urb (urb, GFP_ATOMIC))) {
 273                 err ("%s - failed resubmitting read urb, error %d", __FUNCTION__, result);
 274         }
 275 }
 276
 277 static int safe_write (struct usb_serial_port *port, const unsigned char *buf, int count)
 278 {
 279         unsigned char *data;
 280         int result;
 281         int i;
 282         int packet_length;
 283
 284         dbg ("safe_write port: %p %d urb: %p count: %d", port, port->number, port->write_urb,
 285              count);
 286
 287         if (!port->write_urb) {
 288                 dbg ("%s - write urb NULL", __FUNCTION__);
 289                 return (0);
 290         }
 291
 292         dbg ("safe_write write_urb: %d transfer_buffer_length",
 293              port->write_urb->transfer_buffer_length);
 294
 295         if (!port->write_urb->transfer_buffer_length) {
 296                 dbg ("%s - write urb transfer_buffer_length zero", __FUNCTION__);
 297                 return (0);
 298         }
 299         if (count == 0) {
 300                 dbg ("%s - write request of 0 bytes", __FUNCTION__);
 301                 return (0);
 302         }
 303         spin_lock_bh(&port->lock);
 304         if (port->write_urb_busy) {
 305                 spin_unlock_bh(&port->lock);
 306                 dbg("%s - already writing", __FUNCTION__);
 307                 return 0;
 308         }
 309         port->write_urb_busy = 1;
 310         spin_unlock_bh(&port->lock);
 311
 312         packet_length = port->bulk_out_size;    // get max packetsize
 313
 314         i = packet_length - (safe ? 2 : 0);     // get bytes to send
 315         count = (count > i) ? i : count;
 316
 317
 318         // get the data into the transfer buffer
 319         data = port->write_urb->transfer_buffer;
 320         memset (data, '0', packet_length);
 321
 322         memcpy (data, buf, count);
 323
 324         if (safe) {
 325                 __u16 fcs;
 326
 327                 // pad if necessary
 328                 if (!padded) {
 329                         packet_length = count + 2;
 330                 }
 331                 // set count
 332                 data[packet_length - 2] = count << 2;
 333                 data[packet_length - 1] = 0;
 334
 335                 // compute fcs and insert into trailer
 336                 fcs = fcs_compute10 (data, packet_length, CRC10_INITFCS);
 337                 data[packet_length - 2] |= fcs >> 8;
 338                 data[packet_length - 1] |= fcs & 0xff;
 339
 340                 // set length to send
 341                 port->write_urb->transfer_buffer_length = packet_length;
 342         } else {
 343                 port->write_urb->transfer_buffer_length = count;
 344         }
 345
 346         usb_serial_debug_data(debug, &port->dev, __FUNCTION__, count, port->write_urb->transfer_buffer);
 347 #ifdef ECHO_TX
 348         {
 349                 int i;
 350                 unsigned char *cp = port->write_urb->transfer_buffer;
 351                 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) {
 352                         if ((i % 32) == 0) {
 353                                 printk ("\nsu[%02x] ", i);
 354                         }
 355                         printk ("%02x ", *cp++);
 356                 }
 357                 printk ("\n");
 358         }
 359 #endif
 360         port->write_urb->dev = port->serial->dev;
 361         if ((result = usb_submit_urb (port->write_urb, GFP_KERNEL))) {
 362                 port->write_urb_busy = 0;
 363                 err ("%s - failed submitting write urb, error %d", __FUNCTION__, result);
 364                 return 0;
 365         }
 366         dbg ("%s urb: %p submitted", __FUNCTION__, port->write_urb);
 367
 368         return (count);
 369 }
 370
 371 static int safe_write_room (struct usb_serial_port *port)
 372 {
 373         int room = 0;           // Default: no room
 374
 375         dbg ("%s", __FUNCTION__);
 376
 377         if (port->write_urb_busy)
 378                 room = port->bulk_out_size - (safe ? 2 : 0);
 379
 380         if (room) {
 381                 dbg ("safe_write_room returns %d", room);
 382         }
 383
 384         return (room);
 385 }
 386
 387 static int safe_startup (struct usb_serial *serial)
 388 {
 389         switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) {
 390         case LINEO_SAFESERIAL_CRC:
 391                 break;
 392         case LINEO_SAFESERIAL_CRC_PADDED:
 393                 padded = 1;
 394                 break;
 395         default:
 396                 return -EINVAL;
 397         }
 398         return 0;
 399 }
 400
 401 static struct usb_serial_driver safe_device = {
 402         .driver = {
 403                 .owner =        THIS_MODULE,
 404                 .name =         "safe_serial",
 405         },
 406         .id_table =             id_table,
 407         .usb_driver =           &safe_driver,
 408         .num_interrupt_in =     NUM_DONT_CARE,
 409         .num_bulk_in =          NUM_DONT_CARE,
 410         .num_bulk_out =         NUM_DONT_CARE,
 411         .num_ports =            1,
 412         .write =                safe_write,
 413         .write_room =           safe_write_room,
 414         .read_bulk_callback =   safe_read_bulk_callback,
 415         .attach =               safe_startup,
 416 };
 417
 418 static int __init safe_init (void)
 419 {
 420         int i, retval;
 421
 422         info (DRIVER_VERSION " " DRIVER_AUTHOR);
 423         info (DRIVER_DESC);
 424         info ("vendor: %x product: %x safe: %d padded: %d\n", vendor, product, safe, padded);
 425
 426         // if we have vendor / product parameters patch them into id list
 427         if (vendor || product) {
 428                 info ("vendor: %x product: %x\n", vendor, product);
 429
 430                 for (i = 0; i < ARRAY_SIZE(id_table); i++) {
 431                         if (!id_table[i].idVendor && !id_table[i].idProduct) {
 432                                 id_table[i].idVendor = vendor;
 433                                 id_table[i].idProduct = product;
 434                                 break;
 435                         }
 436                 }
 437         }
 438
 439         retval = usb_serial_register(&safe_device);
 440         if (retval)
 441                 goto failed_usb_serial_register;
 442         retval = usb_register(&safe_driver);
 443         if (retval)
 444                 goto failed_usb_register;
 445
 446         return 0;
 447 failed_usb_register:
 448         usb_serial_deregister(&safe_device);
 449 failed_usb_serial_register:
 450         return retval;
 451 }
 452
 453 static void __exit safe_exit (void)
 454 {
 455         usb_deregister (&safe_driver);
 456         usb_serial_deregister (&safe_device);
 457 }
 458
 459 module_init (safe_init);
 460 module_exit (safe_exit);