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