2 * Safe Encapsulated USB Serial Driver
4 * Copyright (C) 2001 Lineo
5 * Copyright (C) 2001 Hewlett-Packard
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.
13 * Stuart Lynne <sl@lineo.com>, Tom Rushworth <tbr@lineo.com>
17 * The encapsultaion is designed to overcome difficulties with some USB hardware.
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.
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.
28 * Because in this case the sender and receiver are the class and function drivers
29 * there is now end to end protection.
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.
35 * Assuming a packetsize of N:
37 * 0..N-2 data and optional padding
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
44 * | Data Length | 10 bit CRC |
45 * + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 | 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 +
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.
50 * When received a 10 bit CRC is computed over the entire frame including the trailer
51 * and should be equal to zero.
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
57 * See linux/drivers/usbd/serial_fd for a device function driver
58 * implementation of this.
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>
77 #ifndef CONFIG_USB_SERIAL_SAFE_PADDED
78 #define CONFIG_USB_SERIAL_SAFE_PADDED 0
83 static int padded = CONFIG_USB_SERIAL_SAFE_PADDED;
85 #define DRIVER_VERSION "v0.0b"
86 #define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com"
87 #define DRIVER_DESC "USB Safe Encapsulated Serial"
89 MODULE_AUTHOR (DRIVER_AUTHOR);
90 MODULE_DESCRIPTION (DRIVER_DESC);
91 MODULE_LICENSE("GPL");
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)");
100 module_param(debug, bool, S_IRUGO | S_IWUSR);
101 MODULE_PARM_DESC(debug, "Debug enabled or not");
103 module_param(safe, bool, 0);
104 MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
106 module_param(padded, bool, 0);
107 MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
109 #define CDC_DEVICE_CLASS 0x02
111 #define CDC_INTERFACE_CLASS 0x02
112 #define CDC_INTERFACE_SUBCLASS 0x06
114 #define LINEO_INTERFACE_CLASS 0xff
116 #define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01
117 #define LINEO_SAFENET_CRC 0x01
118 #define LINEO_SAFENET_CRC_PADDED 0x02
120 #define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02
121 #define LINEO_SAFESERIAL_CRC 0x01
122 #define LINEO_SAFESERIAL_CRC_PADDED 0x02
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),
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
148 MODULE_DEVICE_TABLE (usb, id_table);
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,
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,
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))
182 * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
183 * @sp: pointer to buffer
184 * @len: number of bytes
187 * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
190 static __u16 __inline__ fcs_compute10 (unsigned char *sp, int len, __u16 fcs)
192 for (; len-- > 0; fcs = CRC10_FCS (fcs, *sp++));
196 static void safe_read_bulk_callback (struct urb *urb)
198 struct usb_serial_port *port = urb->context;
199 unsigned char *data = urb->transfer_buffer;
200 unsigned char length = urb->actual_length;
202 int status = urb->status;
204 dbg ("%s", __func__);
207 dbg("%s - nonzero read bulk status received: %d",
212 dbg ("safe_read_bulk_callback length: %d", port->read_urb->actual_length);
216 unsigned char *cp = port->read_urb->transfer_buffer;
217 for (i = 0; i < port->read_urb->actual_length; i++) {
219 printk ("\nru[%02x] ", i);
221 printk ("%02x ", *cp++);
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->port.tty, data, actual_length);
233 tty_flip_buffer_push (port->port.tty);
235 err ("%s - inconsistent lengths %d:%d", __func__,
236 actual_length, length);
239 err ("%s - bad CRC %x", __func__, fcs);
242 tty_insert_flip_string(port->port.tty, data, length);
243 tty_flip_buffer_push (port->port.tty);
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);
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 */
258 static int safe_write(struct tty_struct *tty, struct usb_serial_port *port,
259 const unsigned char *buf, int count)
266 dbg ("safe_write port: %p %d urb: %p count: %d", port, port->number, port->write_urb,
269 if (!port->write_urb) {
270 dbg ("%s - write urb NULL", __func__);
274 dbg ("safe_write write_urb: %d transfer_buffer_length",
275 port->write_urb->transfer_buffer_length);
277 if (!port->write_urb->transfer_buffer_length) {
278 dbg ("%s - write urb transfer_buffer_length zero", __func__);
282 dbg ("%s - write request of 0 bytes", __func__);
285 spin_lock_bh(&port->lock);
286 if (port->write_urb_busy) {
287 spin_unlock_bh(&port->lock);
288 dbg("%s - already writing", __func__);
291 port->write_urb_busy = 1;
292 spin_unlock_bh(&port->lock);
294 packet_length = port->bulk_out_size; // get max packetsize
296 i = packet_length - (safe ? 2 : 0); // get bytes to send
297 count = (count > i) ? i : count;
300 // get the data into the transfer buffer
301 data = port->write_urb->transfer_buffer;
302 memset (data, '0', packet_length);
304 memcpy (data, buf, count);
311 packet_length = count + 2;
314 data[packet_length - 2] = count << 2;
315 data[packet_length - 1] = 0;
317 // compute fcs and insert into trailer
318 fcs = fcs_compute10 (data, packet_length, CRC10_INITFCS);
319 data[packet_length - 2] |= fcs >> 8;
320 data[packet_length - 1] |= fcs & 0xff;
322 // set length to send
323 port->write_urb->transfer_buffer_length = packet_length;
325 port->write_urb->transfer_buffer_length = count;
328 usb_serial_debug_data(debug, &port->dev, __func__, count, port->write_urb->transfer_buffer);
332 unsigned char *cp = port->write_urb->transfer_buffer;
333 for (i = 0; i < port->write_urb->transfer_buffer_length; i++) {
335 printk ("\nsu[%02x] ", i);
337 printk ("%02x ", *cp++);
342 port->write_urb->dev = port->serial->dev;
343 if ((result = usb_submit_urb (port->write_urb, GFP_KERNEL))) {
344 port->write_urb_busy = 0;
345 err ("%s - failed submitting write urb, error %d", __func__, result);
348 dbg ("%s urb: %p submitted", __func__, port->write_urb);
353 static int safe_write_room(struct tty_struct *tty)
355 struct usb_serial_port *port = tty->driver_data;
356 int room = 0; /* Default: no room */
359 dbg ("%s", __func__);
361 spin_lock_irqsave(&port->lock, flags);
362 if (port->write_urb_busy)
363 room = port->bulk_out_size - (safe ? 2 : 0);
364 spin_unlock_irqrestore(&port->lock, flags);
367 dbg ("safe_write_room returns %d", room);
373 static int safe_startup (struct usb_serial *serial)
375 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) {
376 case LINEO_SAFESERIAL_CRC:
378 case LINEO_SAFESERIAL_CRC_PADDED:
387 static struct usb_serial_driver safe_device = {
389 .owner = THIS_MODULE,
390 .name = "safe_serial",
392 .id_table = id_table,
393 .usb_driver = &safe_driver,
396 .write_room = safe_write_room,
397 .read_bulk_callback = safe_read_bulk_callback,
398 .attach = safe_startup,
401 static int __init safe_init (void)
405 info (DRIVER_VERSION " " DRIVER_AUTHOR);
407 info ("vendor: %x product: %x safe: %d padded: %d\n", vendor, product, safe, padded);
409 // if we have vendor / product parameters patch them into id list
410 if (vendor || product) {
411 info ("vendor: %x product: %x\n", vendor, product);
413 for (i = 0; i < ARRAY_SIZE(id_table); i++) {
414 if (!id_table[i].idVendor && !id_table[i].idProduct) {
415 id_table[i].idVendor = vendor;
416 id_table[i].idProduct = product;
422 retval = usb_serial_register(&safe_device);
424 goto failed_usb_serial_register;
425 retval = usb_register(&safe_driver);
427 goto failed_usb_register;
431 usb_serial_deregister(&safe_device);
432 failed_usb_serial_register:
436 static void __exit safe_exit (void)
438 usb_deregister (&safe_driver);
439 usb_serial_deregister (&safe_device);
442 module_init (safe_init);
443 module_exit (safe_exit);