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 dev_info(&urb->dev->dev, "%s - actual: %d\n", 254 __func__, actual_length); 255 tty_insert_flip_string(tty, 256 data, actual_length); 257 tty_flip_buffer_push(tty); 258 } else { 259 dev_err(&port->dev, 260 "%s - inconsistent lengths %d:%d\n", 261 __func__, actual_length, length); 262 } 263 } else { 264 dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs); 265 } 266 } else { 267 tty_insert_flip_string(tty, data, length); 268 tty_flip_buffer_push(tty); 269 } 270 tty_kref_put(tty); 271 272 /* Continue trying to always read */ 273 usb_fill_bulk_urb(urb, port->serial->dev, 274 usb_rcvbulkpipe(port->serial->dev, 275 port->bulk_in_endpointAddress), 276 urb->transfer_buffer, urb->transfer_buffer_length, 277 safe_read_bulk_callback, port); 278 279 result = usb_submit_urb(urb, GFP_ATOMIC); 280 if (result) 281 dev_err(&port->dev, 282 "%s - failed resubmitting read urb, error %d\n", 283 __func__, result); 284 /* FIXME: Need a mechanism to retry later if this happens */ 285 } 286 287 static int safe_write(struct tty_struct *tty, struct usb_serial_port *port, 288 const unsigned char *buf, int count) 289 { 290 unsigned char *data; 291 int result; 292 int i; 293 int packet_length; 294 295 dbg("safe_write port: %p %d urb: %p count: %d", 296 port, port->number, port->write_urb, count); 297 298 if (!port->write_urb) { 299 dbg("%s - write urb NULL", __func__); 300 return 0; 301 } 302 303 dbg("safe_write write_urb: %d transfer_buffer_length", 304 port->write_urb->transfer_buffer_length); 305 306 if (!port->write_urb->transfer_buffer_length) { 307 dbg("%s - write urb transfer_buffer_length zero", __func__); 308 return 0; 309 } 310 if (count == 0) { 311 dbg("%s - write request of 0 bytes", __func__); 312 return 0; 313 } 314 spin_lock_bh(&port->lock); 315 if (port->write_urb_busy) { 316 spin_unlock_bh(&port->lock); 317 dbg("%s - already writing", __func__); 318 return 0; 319 } 320 port->write_urb_busy = 1; 321 spin_unlock_bh(&port->lock); 322 323 packet_length = port->bulk_out_size; /* get max packetsize */ 324 325 i = packet_length - (safe ? 2 : 0); /* get bytes to send */ 326 count = (count > i) ? i : count; 327 328 329 /* get the data into the transfer buffer */ 330 data = port->write_urb->transfer_buffer; 331 memset(data, '0', packet_length); 332 333 memcpy(data, buf, count); 334 335 if (safe) { 336 __u16 fcs; 337 338 /* pad if necessary */ 339 if (!padded) 340 packet_length = count + 2; 341 /* set count */ 342 data[packet_length - 2] = count << 2; 343 data[packet_length - 1] = 0; 344 345 /* compute fcs and insert into trailer */ 346 fcs = fcs_compute10(data, packet_length, CRC10_INITFCS); 347 data[packet_length - 2] |= fcs >> 8; 348 data[packet_length - 1] |= fcs & 0xff; 349 350 /* set length to send */ 351 port->write_urb->transfer_buffer_length = packet_length; 352 } else { 353 port->write_urb->transfer_buffer_length = count; 354 } 355 356 usb_serial_debug_data(debug, &port->dev, __func__, count, 357 port->write_urb->transfer_buffer); 358 #ifdef ECHO_TX 359 { 360 int i; 361 unsigned char *cp = port->write_urb->transfer_buffer; 362 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) { 363 if ((i % 32) == 0) 364 printk("\nsu[%02x] ", i); 365 printk("%02x ", *cp++); 366 } 367 printk("\n"); 368 } 369 #endif 370 port->write_urb->dev = port->serial->dev; 371 result = usb_submit_urb(port->write_urb, GFP_KERNEL); 372 if (result) { 373 port->write_urb_busy = 0; 374 dev_err(&port->dev, 375 "%s - failed submitting write urb, error %d\n", 376 __func__, result); 377 return 0; 378 } 379 dbg("%s urb: %p submitted", __func__, port->write_urb); 380 381 return count; 382 } 383 384 static int safe_write_room(struct tty_struct *tty) 385 { 386 struct usb_serial_port *port = tty->driver_data; 387 int room = 0; /* Default: no room */ 388 unsigned long flags; 389 390 dbg("%s", __func__); 391 392 spin_lock_irqsave(&port->lock, flags); 393 if (port->write_urb_busy) 394 room = port->bulk_out_size - (safe ? 2 : 0); 395 spin_unlock_irqrestore(&port->lock, flags); 396 397 if (room) 398 dbg("safe_write_room returns %d", room); 399 return room; 400 } 401 402 static int safe_startup(struct usb_serial *serial) 403 { 404 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) { 405 case LINEO_SAFESERIAL_CRC: 406 break; 407 case LINEO_SAFESERIAL_CRC_PADDED: 408 padded = 1; 409 break; 410 default: 411 return -EINVAL; 412 } 413 return 0; 414 } 415 416 static struct usb_serial_driver safe_device = { 417 .driver = { 418 .owner = THIS_MODULE, 419 .name = "safe_serial", 420 }, 421 .id_table = id_table, 422 .usb_driver = &safe_driver, 423 .num_ports = 1, 424 .write = safe_write, 425 .write_room = safe_write_room, 426 .read_bulk_callback = safe_read_bulk_callback, 427 .attach = safe_startup, 428 }; 429 430 static int __init safe_init(void) 431 { 432 int i, retval; 433 434 printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":" 435 DRIVER_DESC "\n"); 436 437 /* if we have vendor / product parameters patch them into id list */ 438 if (vendor || product) { 439 printk(KERN_INFO KBUILD_MODNAME ": vendor: %x product: %x\n", 440 vendor, product); 441 442 for (i = 0; i < ARRAY_SIZE(id_table); i++) { 443 if (!id_table[i].idVendor && !id_table[i].idProduct) { 444 id_table[i].idVendor = vendor; 445 id_table[i].idProduct = product; 446 break; 447 } 448 } 449 } 450 451 retval = usb_serial_register(&safe_device); 452 if (retval) 453 goto failed_usb_serial_register; 454 retval = usb_register(&safe_driver); 455 if (retval) 456 goto failed_usb_register; 457 458 return 0; 459 failed_usb_register: 460 usb_serial_deregister(&safe_device); 461 failed_usb_serial_register: 462 return retval; 463 } 464 465 static void __exit safe_exit(void) 466 { 467 usb_deregister(&safe_driver); 468 usb_serial_deregister(&safe_device); 469 } 470 471 module_init(safe_init); 472 module_exit(safe_exit); 473