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_SERIAL_SAFE_PADDED 78 #define CONFIG_USB_SERIAL_SAFE_PADDED 0 79 #endif 80 81 static int debug; 82 static int safe = 1; 83 static int padded = CONFIG_USB_SERIAL_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 static __u16 vendor; // no default 94 static __u16 product; // no default 95 module_param(vendor, ushort, 0); 96 MODULE_PARM_DESC(vendor, "User specified USB idVendor (required)"); 97 module_param(product, ushort, 0); 98 MODULE_PARM_DESC(product, "User specified USB idProduct (required)"); 99 100 module_param(debug, bool, S_IRUGO | S_IWUSR); 101 MODULE_PARM_DESC(debug, "Debug enabled or not"); 102 103 module_param(safe, bool, 0); 104 MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off"); 105 106 module_param(padded, bool, 0); 107 MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off"); 108 109 #define CDC_DEVICE_CLASS 0x02 110 111 #define CDC_INTERFACE_CLASS 0x02 112 #define CDC_INTERFACE_SUBCLASS 0x06 113 114 #define LINEO_INTERFACE_CLASS 0xff 115 116 #define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01 117 #define LINEO_SAFENET_CRC 0x01 118 #define LINEO_SAFENET_CRC_PADDED 0x02 119 120 #define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02 121 #define LINEO_SAFESERIAL_CRC 0x01 122 #define LINEO_SAFESERIAL_CRC_PADDED 0x02 123 124 125 #define MY_USB_DEVICE(vend,prod,dc,ic,isc) \ 126 .match_flags = USB_DEVICE_ID_MATCH_DEVICE | USB_DEVICE_ID_MATCH_DEV_CLASS | \ 127 USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS, \ 128 .idVendor = (vend), \ 129 .idProduct = (prod),\ 130 .bDeviceClass = (dc),\ 131 .bInterfaceClass = (ic), \ 132 .bInterfaceSubClass = (isc), 133 134 static struct usb_device_id id_table[] = { 135 {MY_USB_DEVICE (0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Itsy 136 {MY_USB_DEVICE (0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Calypso 137 {MY_USB_DEVICE (0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Iris 138 {MY_USB_DEVICE (0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Collie 139 {MY_USB_DEVICE (0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Collie 140 {MY_USB_DEVICE (0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Collie 141 {MY_USB_DEVICE (0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, // Sharp tmp 142 // extra null entry for module 143 // vendor/produc parameters 144 {MY_USB_DEVICE (0, 0, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, 145 {} // terminating entry 146 }; 147 148 MODULE_DEVICE_TABLE (usb, id_table); 149 150 static struct usb_driver safe_driver = { 151 .name = "safe_serial", 152 .probe = usb_serial_probe, 153 .disconnect = usb_serial_disconnect, 154 .id_table = id_table, 155 .no_dynamic_id = 1, 156 }; 157 158 static const __u16 crc10_table[256] = { 159 0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff, 0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe, 160 0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce, 0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf, 161 0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d, 0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c, 162 0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac, 0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad, 163 0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b, 0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a, 164 0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a, 0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b, 165 0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259, 0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158, 166 0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268, 0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169, 167 0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377, 0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076, 168 0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346, 0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047, 169 0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315, 0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014, 170 0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324, 0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025, 171 0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3, 0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2, 172 0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382, 0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083, 173 0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1, 0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0, 174 0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0, 0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1, 175 }; 176 177 #define CRC10_INITFCS 0x000 // Initial FCS value 178 #define CRC10_GOODFCS 0x000 // Good final FCS value 179 #define CRC10_FCS(fcs, c) ( (((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c)) 180 181 /** 182 * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer 183 * @sp: pointer to buffer 184 * @len: number of bytes 185 * @fcs: starting FCS 186 * 187 * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return 188 * new 10 bit FCS. 189 */ 190 static __u16 __inline__ fcs_compute10 (unsigned char *sp, int len, __u16 fcs) 191 { 192 for (; len-- > 0; fcs = CRC10_FCS (fcs, *sp++)); 193 return fcs; 194 } 195 196 static void safe_read_bulk_callback (struct urb *urb) 197 { 198 struct usb_serial_port *port = (struct usb_serial_port *) urb->context; 199 unsigned char *data = urb->transfer_buffer; 200 unsigned char length = urb->actual_length; 201 int i; 202 int result; 203 int status = urb->status; 204 205 dbg ("%s", __FUNCTION__); 206 207 if (status) { 208 dbg("%s - nonzero read bulk status received: %d", 209 __FUNCTION__, status); 210 return; 211 } 212 213 dbg ("safe_read_bulk_callback length: %d", port->read_urb->actual_length); 214 #ifdef ECHO_RCV 215 { 216 int i; 217 unsigned char *cp = port->read_urb->transfer_buffer; 218 for (i = 0; i < port->read_urb->actual_length; i++) { 219 if ((i % 32) == 0) { 220 printk ("\nru[%02x] ", i); 221 } 222 printk ("%02x ", *cp++); 223 } 224 printk ("\n"); 225 } 226 #endif 227 if (safe) { 228 __u16 fcs; 229 if (!(fcs = fcs_compute10 (data, length, CRC10_INITFCS))) { 230 231 int actual_length = data[length - 2] >> 2; 232 233 if (actual_length <= (length - 2)) { 234 235 info ("%s - actual: %d", __FUNCTION__, actual_length); 236 237 for (i = 0; i < actual_length; i++) { 238 tty_insert_flip_char (port->tty, data[i], 0); 239 } 240 tty_flip_buffer_push (port->tty); 241 } else { 242 err ("%s - inconsistent lengths %d:%d", __FUNCTION__, 243 actual_length, length); 244 } 245 } else { 246 err ("%s - bad CRC %x", __FUNCTION__, fcs); 247 } 248 } else { 249 for (i = 0; i < length; i++) { 250 tty_insert_flip_char (port->tty, data[i], 0); 251 } 252 tty_flip_buffer_push (port->tty); 253 } 254 255 /* Continue trying to always read */ 256 usb_fill_bulk_urb (urb, port->serial->dev, 257 usb_rcvbulkpipe (port->serial->dev, port->bulk_in_endpointAddress), 258 urb->transfer_buffer, urb->transfer_buffer_length, 259 safe_read_bulk_callback, port); 260 261 if ((result = usb_submit_urb (urb, GFP_ATOMIC))) { 262 err ("%s - failed resubmitting read urb, error %d", __FUNCTION__, result); 263 } 264 } 265 266 static int safe_write (struct usb_serial_port *port, const unsigned char *buf, int count) 267 { 268 unsigned char *data; 269 int result; 270 int i; 271 int packet_length; 272 273 dbg ("safe_write port: %p %d urb: %p count: %d", port, port->number, port->write_urb, 274 count); 275 276 if (!port->write_urb) { 277 dbg ("%s - write urb NULL", __FUNCTION__); 278 return (0); 279 } 280 281 dbg ("safe_write write_urb: %d transfer_buffer_length", 282 port->write_urb->transfer_buffer_length); 283 284 if (!port->write_urb->transfer_buffer_length) { 285 dbg ("%s - write urb transfer_buffer_length zero", __FUNCTION__); 286 return (0); 287 } 288 if (count == 0) { 289 dbg ("%s - write request of 0 bytes", __FUNCTION__); 290 return (0); 291 } 292 spin_lock_bh(&port->lock); 293 if (port->write_urb_busy) { 294 spin_unlock_bh(&port->lock); 295 dbg("%s - already writing", __FUNCTION__); 296 return 0; 297 } 298 port->write_urb_busy = 1; 299 spin_unlock_bh(&port->lock); 300 301 packet_length = port->bulk_out_size; // get max packetsize 302 303 i = packet_length - (safe ? 2 : 0); // get bytes to send 304 count = (count > i) ? i : count; 305 306 307 // get the data into the transfer buffer 308 data = port->write_urb->transfer_buffer; 309 memset (data, '0', packet_length); 310 311 memcpy (data, buf, count); 312 313 if (safe) { 314 __u16 fcs; 315 316 // pad if necessary 317 if (!padded) { 318 packet_length = count + 2; 319 } 320 // set count 321 data[packet_length - 2] = count << 2; 322 data[packet_length - 1] = 0; 323 324 // compute fcs and insert into trailer 325 fcs = fcs_compute10 (data, packet_length, CRC10_INITFCS); 326 data[packet_length - 2] |= fcs >> 8; 327 data[packet_length - 1] |= fcs & 0xff; 328 329 // set length to send 330 port->write_urb->transfer_buffer_length = packet_length; 331 } else { 332 port->write_urb->transfer_buffer_length = count; 333 } 334 335 usb_serial_debug_data(debug, &port->dev, __FUNCTION__, count, port->write_urb->transfer_buffer); 336 #ifdef ECHO_TX 337 { 338 int i; 339 unsigned char *cp = port->write_urb->transfer_buffer; 340 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) { 341 if ((i % 32) == 0) { 342 printk ("\nsu[%02x] ", i); 343 } 344 printk ("%02x ", *cp++); 345 } 346 printk ("\n"); 347 } 348 #endif 349 port->write_urb->dev = port->serial->dev; 350 if ((result = usb_submit_urb (port->write_urb, GFP_KERNEL))) { 351 port->write_urb_busy = 0; 352 err ("%s - failed submitting write urb, error %d", __FUNCTION__, result); 353 return 0; 354 } 355 dbg ("%s urb: %p submitted", __FUNCTION__, port->write_urb); 356 357 return (count); 358 } 359 360 static int safe_write_room (struct usb_serial_port *port) 361 { 362 int room = 0; // Default: no room 363 364 dbg ("%s", __FUNCTION__); 365 366 if (port->write_urb_busy) 367 room = port->bulk_out_size - (safe ? 2 : 0); 368 369 if (room) { 370 dbg ("safe_write_room returns %d", room); 371 } 372 373 return (room); 374 } 375 376 static int safe_startup (struct usb_serial *serial) 377 { 378 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) { 379 case LINEO_SAFESERIAL_CRC: 380 break; 381 case LINEO_SAFESERIAL_CRC_PADDED: 382 padded = 1; 383 break; 384 default: 385 return -EINVAL; 386 } 387 return 0; 388 } 389 390 static struct usb_serial_driver safe_device = { 391 .driver = { 392 .owner = THIS_MODULE, 393 .name = "safe_serial", 394 }, 395 .id_table = id_table, 396 .usb_driver = &safe_driver, 397 .num_interrupt_in = NUM_DONT_CARE, 398 .num_bulk_in = NUM_DONT_CARE, 399 .num_bulk_out = NUM_DONT_CARE, 400 .num_ports = 1, 401 .write = safe_write, 402 .write_room = safe_write_room, 403 .read_bulk_callback = safe_read_bulk_callback, 404 .attach = safe_startup, 405 }; 406 407 static int __init safe_init (void) 408 { 409 int i, retval; 410 411 info (DRIVER_VERSION " " DRIVER_AUTHOR); 412 info (DRIVER_DESC); 413 info ("vendor: %x product: %x safe: %d padded: %d\n", vendor, product, safe, padded); 414 415 // if we have vendor / product parameters patch them into id list 416 if (vendor || product) { 417 info ("vendor: %x product: %x\n", vendor, product); 418 419 for (i = 0; i < ARRAY_SIZE(id_table); i++) { 420 if (!id_table[i].idVendor && !id_table[i].idProduct) { 421 id_table[i].idVendor = vendor; 422 id_table[i].idProduct = product; 423 break; 424 } 425 } 426 } 427 428 retval = usb_serial_register(&safe_device); 429 if (retval) 430 goto failed_usb_serial_register; 431 retval = usb_register(&safe_driver); 432 if (retval) 433 goto failed_usb_register; 434 435 return 0; 436 failed_usb_register: 437 usb_serial_deregister(&safe_device); 438 failed_usb_serial_register: 439 return retval; 440 } 441 442 static void __exit safe_exit (void) 443 { 444 usb_deregister (&safe_driver); 445 usb_serial_deregister (&safe_device); 446 } 447 448 module_init (safe_init); 449 module_exit (safe_exit); 450