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 .name = "safe_serial", 164 .probe = usb_serial_probe, 165 .disconnect = usb_serial_disconnect, 166 .id_table = id_table, 167 .no_dynamic_id = 1, 168 }; 169 170 static const __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 < ARRAY_SIZE(id_table); 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); 459