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 = urb->context; 199 unsigned char *data = urb->transfer_buffer; 200 unsigned char length = urb->actual_length; 201 int result; 202 int status = urb->status; 203 204 dbg ("%s", __func__); 205 206 if (status) { 207 dbg("%s - nonzero read bulk status received: %d", 208 __func__, status); 209 return; 210 } 211 212 dbg ("safe_read_bulk_callback length: %d", port->read_urb->actual_length); 213 #ifdef ECHO_RCV 214 { 215 int i; 216 unsigned char *cp = port->read_urb->transfer_buffer; 217 for (i = 0; i < port->read_urb->actual_length; i++) { 218 if ((i % 32) == 0) { 219 printk ("\nru[%02x] ", i); 220 } 221 printk ("%02x ", *cp++); 222 } 223 printk ("\n"); 224 } 225 #endif 226 if (safe) { 227 __u16 fcs; 228 if (!(fcs = fcs_compute10 (data, length, CRC10_INITFCS))) { 229 int actual_length = data[length - 2] >> 2; 230 if (actual_length <= (length - 2)) { 231 info ("%s - actual: %d", __func__, actual_length); 232 tty_insert_flip_string(port->tty, data, actual_length); 233 tty_flip_buffer_push (port->tty); 234 } else { 235 err ("%s - inconsistent lengths %d:%d", __func__, 236 actual_length, length); 237 } 238 } else { 239 err ("%s - bad CRC %x", __func__, fcs); 240 } 241 } else { 242 tty_insert_flip_string(port->tty, data, length); 243 tty_flip_buffer_push (port->tty); 244 } 245 246 /* Continue trying to always read */ 247 usb_fill_bulk_urb (urb, port->serial->dev, 248 usb_rcvbulkpipe (port->serial->dev, port->bulk_in_endpointAddress), 249 urb->transfer_buffer, urb->transfer_buffer_length, 250 safe_read_bulk_callback, port); 251 252 if ((result = usb_submit_urb (urb, GFP_ATOMIC))) { 253 err ("%s - failed resubmitting read urb, error %d", __func__, result); 254 /* FIXME: Need a mechanism to retry later if this happens */ 255 } 256 } 257 258 static int safe_write (struct usb_serial_port *port, const unsigned char *buf, int count) 259 { 260 unsigned char *data; 261 int result; 262 int i; 263 int packet_length; 264 265 dbg ("safe_write port: %p %d urb: %p count: %d", port, port->number, port->write_urb, 266 count); 267 268 if (!port->write_urb) { 269 dbg ("%s - write urb NULL", __func__); 270 return 0; 271 } 272 273 dbg ("safe_write write_urb: %d transfer_buffer_length", 274 port->write_urb->transfer_buffer_length); 275 276 if (!port->write_urb->transfer_buffer_length) { 277 dbg ("%s - write urb transfer_buffer_length zero", __func__); 278 return 0; 279 } 280 if (count == 0) { 281 dbg ("%s - write request of 0 bytes", __func__); 282 return 0; 283 } 284 spin_lock_bh(&port->lock); 285 if (port->write_urb_busy) { 286 spin_unlock_bh(&port->lock); 287 dbg("%s - already writing", __func__); 288 return 0; 289 } 290 port->write_urb_busy = 1; 291 spin_unlock_bh(&port->lock); 292 293 packet_length = port->bulk_out_size; // get max packetsize 294 295 i = packet_length - (safe ? 2 : 0); // get bytes to send 296 count = (count > i) ? i : count; 297 298 299 // get the data into the transfer buffer 300 data = port->write_urb->transfer_buffer; 301 memset (data, '0', packet_length); 302 303 memcpy (data, buf, count); 304 305 if (safe) { 306 __u16 fcs; 307 308 // pad if necessary 309 if (!padded) { 310 packet_length = count + 2; 311 } 312 // set count 313 data[packet_length - 2] = count << 2; 314 data[packet_length - 1] = 0; 315 316 // compute fcs and insert into trailer 317 fcs = fcs_compute10 (data, packet_length, CRC10_INITFCS); 318 data[packet_length - 2] |= fcs >> 8; 319 data[packet_length - 1] |= fcs & 0xff; 320 321 // set length to send 322 port->write_urb->transfer_buffer_length = packet_length; 323 } else { 324 port->write_urb->transfer_buffer_length = count; 325 } 326 327 usb_serial_debug_data(debug, &port->dev, __func__, count, port->write_urb->transfer_buffer); 328 #ifdef ECHO_TX 329 { 330 int i; 331 unsigned char *cp = port->write_urb->transfer_buffer; 332 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) { 333 if ((i % 32) == 0) { 334 printk ("\nsu[%02x] ", i); 335 } 336 printk ("%02x ", *cp++); 337 } 338 printk ("\n"); 339 } 340 #endif 341 port->write_urb->dev = port->serial->dev; 342 if ((result = usb_submit_urb (port->write_urb, GFP_KERNEL))) { 343 port->write_urb_busy = 0; 344 err ("%s - failed submitting write urb, error %d", __func__, result); 345 return 0; 346 } 347 dbg ("%s urb: %p submitted", __func__, port->write_urb); 348 349 return (count); 350 } 351 352 static int safe_write_room (struct usb_serial_port *port) 353 { 354 int room = 0; /* Default: no room */ 355 unsigned long flags; 356 357 dbg ("%s", __func__); 358 359 spin_lock_irqsave(&port->lock, flags); 360 if (port->write_urb_busy) 361 room = port->bulk_out_size - (safe ? 2 : 0); 362 spin_unlock_irqrestore(&port->lock, flags); 363 364 if (room) { 365 dbg ("safe_write_room returns %d", room); 366 } 367 368 return room; 369 } 370 371 static int safe_startup (struct usb_serial *serial) 372 { 373 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) { 374 case LINEO_SAFESERIAL_CRC: 375 break; 376 case LINEO_SAFESERIAL_CRC_PADDED: 377 padded = 1; 378 break; 379 default: 380 return -EINVAL; 381 } 382 return 0; 383 } 384 385 static struct usb_serial_driver safe_device = { 386 .driver = { 387 .owner = THIS_MODULE, 388 .name = "safe_serial", 389 }, 390 .id_table = id_table, 391 .usb_driver = &safe_driver, 392 .num_ports = 1, 393 .write = safe_write, 394 .write_room = safe_write_room, 395 .read_bulk_callback = safe_read_bulk_callback, 396 .attach = safe_startup, 397 }; 398 399 static int __init safe_init (void) 400 { 401 int i, retval; 402 403 info (DRIVER_VERSION " " DRIVER_AUTHOR); 404 info (DRIVER_DESC); 405 info ("vendor: %x product: %x safe: %d padded: %d\n", vendor, product, safe, padded); 406 407 // if we have vendor / product parameters patch them into id list 408 if (vendor || product) { 409 info ("vendor: %x product: %x\n", vendor, product); 410 411 for (i = 0; i < ARRAY_SIZE(id_table); i++) { 412 if (!id_table[i].idVendor && !id_table[i].idProduct) { 413 id_table[i].idVendor = vendor; 414 id_table[i].idProduct = product; 415 break; 416 } 417 } 418 } 419 420 retval = usb_serial_register(&safe_device); 421 if (retval) 422 goto failed_usb_serial_register; 423 retval = usb_register(&safe_driver); 424 if (retval) 425 goto failed_usb_register; 426 427 return 0; 428 failed_usb_register: 429 usb_serial_deregister(&safe_device); 430 failed_usb_serial_register: 431 return retval; 432 } 433 434 static void __exit safe_exit (void) 435 { 436 usb_deregister (&safe_driver); 437 usb_serial_deregister (&safe_device); 438 } 439 440 module_init (safe_init); 441 module_exit (safe_exit); 442