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_SAFE_PADDED 78 #define CONFIG_USB_SAFE_PADDED 0 79 #endif 80 81 static int debug; 82 static int safe = 1; 83 static int padded = CONFIG_USB_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; 214 215 dbg ("%s", __FUNCTION__); 216 217 if (urb->status) { 218 dbg ("%s - nonzero read bulk status received: %d", __FUNCTION__, urb->status); 219 return; 220 } 221 222 dbg ("safe_read_bulk_callback length: %d", port->read_urb->actual_length); 223 #ifdef ECHO_RCV 224 { 225 int i; 226 unsigned char *cp = port->read_urb->transfer_buffer; 227 for (i = 0; i < port->read_urb->actual_length; i++) { 228 if ((i % 32) == 0) { 229 printk ("\nru[%02x] ", i); 230 } 231 printk ("%02x ", *cp++); 232 } 233 printk ("\n"); 234 } 235 #endif 236 if (safe) { 237 __u16 fcs; 238 if (!(fcs = fcs_compute10 (data, length, CRC10_INITFCS))) { 239 240 int actual_length = data[length - 2] >> 2; 241 242 if (actual_length <= (length - 2)) { 243 244 info ("%s - actual: %d", __FUNCTION__, actual_length); 245 246 for (i = 0; i < actual_length; i++) { 247 tty_insert_flip_char (port->tty, data[i], 0); 248 } 249 tty_flip_buffer_push (port->tty); 250 } else { 251 err ("%s - inconsistent lengths %d:%d", __FUNCTION__, 252 actual_length, length); 253 } 254 } else { 255 err ("%s - bad CRC %x", __FUNCTION__, fcs); 256 } 257 } else { 258 for (i = 0; i < length; i++) { 259 tty_insert_flip_char (port->tty, data[i], 0); 260 } 261 tty_flip_buffer_push (port->tty); 262 } 263 264 /* Continue trying to always read */ 265 usb_fill_bulk_urb (urb, port->serial->dev, 266 usb_rcvbulkpipe (port->serial->dev, port->bulk_in_endpointAddress), 267 urb->transfer_buffer, urb->transfer_buffer_length, 268 safe_read_bulk_callback, port); 269 270 if ((result = usb_submit_urb (urb, GFP_ATOMIC))) { 271 err ("%s - failed resubmitting read urb, error %d", __FUNCTION__, result); 272 } 273 } 274 275 static int safe_write (struct usb_serial_port *port, const unsigned char *buf, int count) 276 { 277 unsigned char *data; 278 int result; 279 int i; 280 int packet_length; 281 282 dbg ("safe_write port: %p %d urb: %p count: %d", port, port->number, port->write_urb, 283 count); 284 285 if (!port->write_urb) { 286 dbg ("%s - write urb NULL", __FUNCTION__); 287 return (0); 288 } 289 290 dbg ("safe_write write_urb: %d transfer_buffer_length", 291 port->write_urb->transfer_buffer_length); 292 293 if (!port->write_urb->transfer_buffer_length) { 294 dbg ("%s - write urb transfer_buffer_length zero", __FUNCTION__); 295 return (0); 296 } 297 if (count == 0) { 298 dbg ("%s - write request of 0 bytes", __FUNCTION__); 299 return (0); 300 } 301 spin_lock_bh(&port->lock); 302 if (port->write_urb_busy) { 303 spin_unlock_bh(&port->lock); 304 dbg("%s - already writing", __FUNCTION__); 305 return 0; 306 } 307 port->write_urb_busy = 1; 308 spin_unlock_bh(&port->lock); 309 310 packet_length = port->bulk_out_size; // get max packetsize 311 312 i = packet_length - (safe ? 2 : 0); // get bytes to send 313 count = (count > i) ? i : count; 314 315 316 // get the data into the transfer buffer 317 data = port->write_urb->transfer_buffer; 318 memset (data, '0', packet_length); 319 320 memcpy (data, buf, count); 321 322 if (safe) { 323 __u16 fcs; 324 325 // pad if necessary 326 if (!padded) { 327 packet_length = count + 2; 328 } 329 // set count 330 data[packet_length - 2] = count << 2; 331 data[packet_length - 1] = 0; 332 333 // compute fcs and insert into trailer 334 fcs = fcs_compute10 (data, packet_length, CRC10_INITFCS); 335 data[packet_length - 2] |= fcs >> 8; 336 data[packet_length - 1] |= fcs & 0xff; 337 338 // set length to send 339 port->write_urb->transfer_buffer_length = packet_length; 340 } else { 341 port->write_urb->transfer_buffer_length = count; 342 } 343 344 usb_serial_debug_data(debug, &port->dev, __FUNCTION__, count, port->write_urb->transfer_buffer); 345 #ifdef ECHO_TX 346 { 347 int i; 348 unsigned char *cp = port->write_urb->transfer_buffer; 349 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) { 350 if ((i % 32) == 0) { 351 printk ("\nsu[%02x] ", i); 352 } 353 printk ("%02x ", *cp++); 354 } 355 printk ("\n"); 356 } 357 #endif 358 port->write_urb->dev = port->serial->dev; 359 if ((result = usb_submit_urb (port->write_urb, GFP_KERNEL))) { 360 port->write_urb_busy = 0; 361 err ("%s - failed submitting write urb, error %d", __FUNCTION__, result); 362 return 0; 363 } 364 dbg ("%s urb: %p submitted", __FUNCTION__, port->write_urb); 365 366 return (count); 367 } 368 369 static int safe_write_room (struct usb_serial_port *port) 370 { 371 int room = 0; // Default: no room 372 373 dbg ("%s", __FUNCTION__); 374 375 if (port->write_urb_busy) 376 room = port->bulk_out_size - (safe ? 2 : 0); 377 378 if (room) { 379 dbg ("safe_write_room returns %d", room); 380 } 381 382 return (room); 383 } 384 385 static int safe_startup (struct usb_serial *serial) 386 { 387 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) { 388 case LINEO_SAFESERIAL_CRC: 389 break; 390 case LINEO_SAFESERIAL_CRC_PADDED: 391 padded = 1; 392 break; 393 default: 394 return -EINVAL; 395 } 396 return 0; 397 } 398 399 static struct usb_serial_driver safe_device = { 400 .driver = { 401 .owner = THIS_MODULE, 402 .name = "safe_serial", 403 }, 404 .id_table = id_table, 405 .usb_driver = &safe_driver, 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