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 struct tty_struct *tty; 221 int result; 222 int status = urb->status; 223 224 dbg("%s", __func__); 225 226 if (status) { 227 dbg("%s - nonzero read bulk status received: %d", 228 __func__, status); 229 return; 230 } 231 232 dbg("safe_read_bulk_callback length: %d", 233 port->read_urb->actual_length); 234 #ifdef ECHO_RCV 235 { 236 int i; 237 unsigned char *cp = port->read_urb->transfer_buffer; 238 for (i = 0; i < port->read_urb->actual_length; i++) { 239 if ((i % 32) == 0) 240 printk("\nru[%02x] ", i); 241 printk("%02x ", *cp++); 242 } 243 printk("\n"); 244 } 245 #endif 246 tty = tty_port_tty_get(&port->port); 247 if (safe) { 248 __u16 fcs; 249 fcs = fcs_compute10(data, length, CRC10_INITFCS); 250 if (!fcs) { 251 int actual_length = data[length - 2] >> 2; 252 if (actual_length <= (length - 2)) { 253 info("%s - actual: %d", __func__, 254 actual_length); 255 tty_insert_flip_string(tty, 256 data, actual_length); 257 tty_flip_buffer_push(tty); 258 } else { 259 err("%s - inconsistent lengths %d:%d", 260 __func__, actual_length, length); 261 } 262 } else { 263 err("%s - bad CRC %x", __func__, fcs); 264 } 265 } else { 266 tty_insert_flip_string(tty, data, length); 267 tty_flip_buffer_push(tty); 268 } 269 tty_kref_put(tty); 270 271 /* Continue trying to always read */ 272 usb_fill_bulk_urb(urb, port->serial->dev, 273 usb_rcvbulkpipe(port->serial->dev, 274 port->bulk_in_endpointAddress), 275 urb->transfer_buffer, urb->transfer_buffer_length, 276 safe_read_bulk_callback, port); 277 278 result = usb_submit_urb(urb, GFP_ATOMIC); 279 if (result) 280 err("%s - failed resubmitting read urb, error %d", 281 __func__, result); 282 /* FIXME: Need a mechanism to retry later if this happens */ 283 } 284 285 static int safe_write(struct tty_struct *tty, struct usb_serial_port *port, 286 const unsigned char *buf, int count) 287 { 288 unsigned char *data; 289 int result; 290 int i; 291 int packet_length; 292 293 dbg("safe_write port: %p %d urb: %p count: %d", 294 port, port->number, port->write_urb, count); 295 296 if (!port->write_urb) { 297 dbg("%s - write urb NULL", __func__); 298 return 0; 299 } 300 301 dbg("safe_write write_urb: %d transfer_buffer_length", 302 port->write_urb->transfer_buffer_length); 303 304 if (!port->write_urb->transfer_buffer_length) { 305 dbg("%s - write urb transfer_buffer_length zero", __func__); 306 return 0; 307 } 308 if (count == 0) { 309 dbg("%s - write request of 0 bytes", __func__); 310 return 0; 311 } 312 spin_lock_bh(&port->lock); 313 if (port->write_urb_busy) { 314 spin_unlock_bh(&port->lock); 315 dbg("%s - already writing", __func__); 316 return 0; 317 } 318 port->write_urb_busy = 1; 319 spin_unlock_bh(&port->lock); 320 321 packet_length = port->bulk_out_size; /* get max packetsize */ 322 323 i = packet_length - (safe ? 2 : 0); /* get bytes to send */ 324 count = (count > i) ? i : count; 325 326 327 /* get the data into the transfer buffer */ 328 data = port->write_urb->transfer_buffer; 329 memset(data, '0', packet_length); 330 331 memcpy(data, buf, count); 332 333 if (safe) { 334 __u16 fcs; 335 336 /* pad if necessary */ 337 if (!padded) 338 packet_length = count + 2; 339 /* set count */ 340 data[packet_length - 2] = count << 2; 341 data[packet_length - 1] = 0; 342 343 /* compute fcs and insert into trailer */ 344 fcs = fcs_compute10(data, packet_length, CRC10_INITFCS); 345 data[packet_length - 2] |= fcs >> 8; 346 data[packet_length - 1] |= fcs & 0xff; 347 348 /* set length to send */ 349 port->write_urb->transfer_buffer_length = packet_length; 350 } else { 351 port->write_urb->transfer_buffer_length = count; 352 } 353 354 usb_serial_debug_data(debug, &port->dev, __func__, count, 355 port->write_urb->transfer_buffer); 356 #ifdef ECHO_TX 357 { 358 int i; 359 unsigned char *cp = port->write_urb->transfer_buffer; 360 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) { 361 if ((i % 32) == 0) 362 printk("\nsu[%02x] ", i); 363 printk("%02x ", *cp++); 364 } 365 printk("\n"); 366 } 367 #endif 368 port->write_urb->dev = port->serial->dev; 369 result = usb_submit_urb(port->write_urb, GFP_KERNEL); 370 if (result) { 371 port->write_urb_busy = 0; 372 err("%s - failed submitting write urb, error %d", 373 __func__, result); 374 return 0; 375 } 376 dbg("%s urb: %p submitted", __func__, port->write_urb); 377 378 return count; 379 } 380 381 static int safe_write_room(struct tty_struct *tty) 382 { 383 struct usb_serial_port *port = tty->driver_data; 384 int room = 0; /* Default: no room */ 385 unsigned long flags; 386 387 dbg("%s", __func__); 388 389 spin_lock_irqsave(&port->lock, flags); 390 if (port->write_urb_busy) 391 room = port->bulk_out_size - (safe ? 2 : 0); 392 spin_unlock_irqrestore(&port->lock, flags); 393 394 if (room) 395 dbg("safe_write_room returns %d", room); 396 return room; 397 } 398 399 static int safe_startup(struct usb_serial *serial) 400 { 401 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) { 402 case LINEO_SAFESERIAL_CRC: 403 break; 404 case LINEO_SAFESERIAL_CRC_PADDED: 405 padded = 1; 406 break; 407 default: 408 return -EINVAL; 409 } 410 return 0; 411 } 412 413 static struct usb_serial_driver safe_device = { 414 .driver = { 415 .owner = THIS_MODULE, 416 .name = "safe_serial", 417 }, 418 .id_table = id_table, 419 .usb_driver = &safe_driver, 420 .num_ports = 1, 421 .write = safe_write, 422 .write_room = safe_write_room, 423 .read_bulk_callback = safe_read_bulk_callback, 424 .attach = safe_startup, 425 }; 426 427 static int __init safe_init(void) 428 { 429 int i, retval; 430 431 info(DRIVER_VERSION " " DRIVER_AUTHOR); 432 info(DRIVER_DESC); 433 info("vendor: %x product: %x safe: %d padded: %d\n", 434 vendor, product, safe, padded); 435 436 /* if we have vendor / product parameters patch them into id list */ 437 if (vendor || product) { 438 info("vendor: %x product: %x\n", vendor, product); 439 440 for (i = 0; i < ARRAY_SIZE(id_table); i++) { 441 if (!id_table[i].idVendor && !id_table[i].idProduct) { 442 id_table[i].idVendor = vendor; 443 id_table[i].idProduct = product; 444 break; 445 } 446 } 447 } 448 449 retval = usb_serial_register(&safe_device); 450 if (retval) 451 goto failed_usb_serial_register; 452 retval = usb_register(&safe_driver); 453 if (retval) 454 goto failed_usb_register; 455 456 return 0; 457 failed_usb_register: 458 usb_serial_deregister(&safe_device); 459 failed_usb_serial_register: 460 return retval; 461 } 462 463 static void __exit safe_exit(void) 464 { 465 usb_deregister(&safe_driver); 466 usb_serial_deregister(&safe_device); 467 } 468 469 module_init(safe_init); 470 module_exit(safe_exit); 471