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1/*
2 * Safe Encapsulated USB Serial Driver
3 *
4 * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
5 * Copyright (C) 2001 Lineo
6 * Copyright (C) 2001 Hewlett-Packard
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * By:
14 * Stuart Lynne <sl@lineo.com>, Tom Rushworth <tbr@lineo.com>
15 */
16
17/*
18 * The encapsultaion is designed to overcome difficulties with some USB
19 * hardware.
20 *
21 * While the USB protocol has a CRC over the data while in transit, i.e. while
22 * being carried over the bus, there is no end to end protection. If the
23 * hardware has any problems getting the data into or out of the USB transmit
24 * and receive FIFO's then data can be lost.
25 *
26 * This protocol adds a two byte trailer to each USB packet to specify the
27 * number of bytes of valid data and a 10 bit CRC that will allow the receiver
28 * to verify that the entire USB packet was received without error.
29 *
30 * Because in this case the sender and receiver are the class and function
31 * drivers there is now end to end protection.
32 *
33 * There is an additional option that can be used to force all transmitted
34 * packets to be padded to the maximum packet size. This provides a work
35 * around for some devices which have problems with small USB packets.
36 *
37 * Assuming a packetsize of N:
38 *
39 * 0..N-2 data and optional padding
40 *
41 * N-2 bits 7-2 - number of bytes of valid data
42 * bits 1-0 top two bits of 10 bit CRC
43 * N-1 bottom 8 bits of 10 bit CRC
44 *
45 *
46 * | Data Length | 10 bit CRC |
47 * + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 | 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 +
48 *
49 * The 10 bit CRC is computed across the sent data, followed by the trailer
50 * with the length set and the CRC set to zero. The CRC is then OR'd into
51 * the trailer.
52 *
53 * When received a 10 bit CRC is computed over the entire frame including
54 * the trailer and should be equal to zero.
55 *
56 * Two module parameters are used to control the encapsulation, if both are
57 * turned of the module works as a simple serial device with NO
58 * encapsulation.
59 *
60 * See linux/drivers/usbd/serial_fd for a device function driver
61 * implementation of this.
62 *
63 */
64
65
66#include <linux/kernel.h>
67#include <linux/errno.h>
68#include <linux/gfp.h>
69#include <linux/init.h>
70#include <linux/tty.h>
71#include <linux/tty_driver.h>
72#include <linux/tty_flip.h>
73#include <linux/module.h>
74#include <linux/spinlock.h>
75#include <linux/uaccess.h>
76#include <linux/usb.h>
77#include <linux/usb/serial.h>
78
79
80#ifndef CONFIG_USB_SERIAL_SAFE_PADDED
81#define CONFIG_USB_SERIAL_SAFE_PADDED 0
82#endif
83
84static int debug;
85static int safe = 1;
86static int padded = CONFIG_USB_SERIAL_SAFE_PADDED;
87
88#define DRIVER_VERSION "v0.1"
89#define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com, Johan Hovold <jhovold@gmail.com>"
90#define DRIVER_DESC "USB Safe Encapsulated Serial"
91
92MODULE_AUTHOR(DRIVER_AUTHOR);
93MODULE_DESCRIPTION(DRIVER_DESC);
94MODULE_LICENSE("GPL");
95
96static __u16 vendor; /* no default */
97static __u16 product; /* no default */
98module_param(vendor, ushort, 0);
99MODULE_PARM_DESC(vendor, "User specified USB idVendor (required)");
100module_param(product, ushort, 0);
101MODULE_PARM_DESC(product, "User specified USB idProduct (required)");
102
103module_param(debug, bool, S_IRUGO | S_IWUSR);
104MODULE_PARM_DESC(debug, "Debug enabled or not");
105
106module_param(safe, bool, 0);
107MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
108
109module_param(padded, bool, 0);
110MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
111
112#define CDC_DEVICE_CLASS 0x02
113
114#define CDC_INTERFACE_CLASS 0x02
115#define CDC_INTERFACE_SUBCLASS 0x06
116
117#define LINEO_INTERFACE_CLASS 0xff
118
119#define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01
120#define LINEO_SAFENET_CRC 0x01
121#define LINEO_SAFENET_CRC_PADDED 0x02
122
123#define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02
124#define LINEO_SAFESERIAL_CRC 0x01
125#define LINEO_SAFESERIAL_CRC_PADDED 0x02
126
127
128#define MY_USB_DEVICE(vend, prod, dc, ic, isc) \
129 .match_flags = USB_DEVICE_ID_MATCH_DEVICE | \
130 USB_DEVICE_ID_MATCH_DEV_CLASS | \
131 USB_DEVICE_ID_MATCH_INT_CLASS | \
132 USB_DEVICE_ID_MATCH_INT_SUBCLASS, \
133 .idVendor = (vend), \
134 .idProduct = (prod),\
135 .bDeviceClass = (dc),\
136 .bInterfaceClass = (ic), \
137 .bInterfaceSubClass = (isc),
138
139static struct usb_device_id id_table[] = {
140 {MY_USB_DEVICE(0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Itsy */
141 {MY_USB_DEVICE(0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Calypso */
142 {MY_USB_DEVICE(0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Iris */
143 {MY_USB_DEVICE(0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
144 {MY_USB_DEVICE(0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
145 {MY_USB_DEVICE(0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
146 {MY_USB_DEVICE(0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Sharp tmp */
147 /* extra null entry for module vendor/produc parameters */
148 {MY_USB_DEVICE(0, 0, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)},
149 {} /* terminating entry */
150};
151
152MODULE_DEVICE_TABLE(usb, id_table);
153
154static struct usb_driver safe_driver = {
155 .name = "safe_serial",
156 .probe = usb_serial_probe,
157 .disconnect = usb_serial_disconnect,
158 .id_table = id_table,
159 .no_dynamic_id = 1,
160};
161
162static const __u16 crc10_table[256] = {
163 0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff,
164 0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
165 0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce,
166 0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
167 0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d,
168 0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
169 0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac,
170 0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
171 0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b,
172 0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
173 0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a,
174 0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
175 0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259,
176 0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
177 0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268,
178 0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
179 0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377,
180 0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
181 0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346,
182 0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
183 0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315,
184 0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
185 0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324,
186 0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
187 0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3,
188 0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
189 0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382,
190 0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
191 0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1,
192 0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
193 0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0,
194 0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
195};
196
197#define CRC10_INITFCS 0x000 /* Initial FCS value */
198#define CRC10_GOODFCS 0x000 /* Good final FCS value */
199#define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
200
201/**
202 * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
203 * @sp: pointer to buffer
204 * @len: number of bytes
205 * @fcs: starting FCS
206 *
207 * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
208 * new 10 bit FCS.
209 */
210static __u16 __inline__ fcs_compute10(unsigned char *sp, int len, __u16 fcs)
211{
212 for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++));
213 return fcs;
214}
215
216static void safe_process_read_urb(struct urb *urb)
217{
218 struct usb_serial_port *port = urb->context;
219 unsigned char *data = urb->transfer_buffer;
220 unsigned char length = urb->actual_length;
221 int actual_length;
222 struct tty_struct *tty;
223 __u16 fcs;
224
225 if (!length)
226 return;
227
228 tty = tty_port_tty_get(&port->port);
229 if (!tty)
230 return;
231
232 if (!safe)
233 goto out;
234
235 fcs = fcs_compute10(data, length, CRC10_INITFCS);
236 if (fcs) {
237 dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);
238 goto err;
239 }
240
241 actual_length = data[length - 2] >> 2;
242 if (actual_length > (length - 2)) {
243 dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n",
244 __func__, actual_length, length);
245 goto err;
246 }
247 dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length);
248 length = actual_length;
249out:
250 tty_insert_flip_string(tty, data, length);
251 tty_flip_buffer_push(tty);
252err:
253 tty_kref_put(tty);
254}
255
256static int safe_prepare_write_buffer(struct usb_serial_port *port,
257 void *dest, size_t size)
258{
259 unsigned char *buf = dest;
260 int count;
261 int trailer_len;
262 int pkt_len;
263 __u16 fcs;
264
265 trailer_len = safe ? 2 : 0;
266
267 count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len,
268 &port->lock);
269 if (!safe)
270 return count;
271
272 /* pad if necessary */
273 if (padded) {
274 pkt_len = size;
275 memset(buf + count, '0', pkt_len - count - trailer_len);
276 } else {
277 pkt_len = count + trailer_len;
278 }
279
280 /* set count */
281 buf[pkt_len - 2] = count << 2;
282 buf[pkt_len - 1] = 0;
283
284 /* compute fcs and insert into trailer */
285 fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS);
286 buf[pkt_len - 2] |= fcs >> 8;
287 buf[pkt_len - 1] |= fcs & 0xff;
288
289 return pkt_len;
290}
291
292static int safe_startup(struct usb_serial *serial)
293{
294 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) {
295 case LINEO_SAFESERIAL_CRC:
296 break;
297 case LINEO_SAFESERIAL_CRC_PADDED:
298 padded = 1;
299 break;
300 default:
301 return -EINVAL;
302 }
303 return 0;
304}
305
306static struct usb_serial_driver safe_device = {
307 .driver = {
308 .owner = THIS_MODULE,
309 .name = "safe_serial",
310 },
311 .id_table = id_table,
312 .usb_driver = &safe_driver,
313 .num_ports = 1,
314 .process_read_urb = safe_process_read_urb,
315 .prepare_write_buffer = safe_prepare_write_buffer,
316 .attach = safe_startup,
317};
318
319static int __init safe_init(void)
320{
321 int i, retval;
322
323 printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
324 DRIVER_DESC "\n");
325
326 /* if we have vendor / product parameters patch them into id list */
327 if (vendor || product) {
328 printk(KERN_INFO KBUILD_MODNAME ": vendor: %x product: %x\n",
329 vendor, product);
330
331 for (i = 0; i < ARRAY_SIZE(id_table); i++) {
332 if (!id_table[i].idVendor && !id_table[i].idProduct) {
333 id_table[i].idVendor = vendor;
334 id_table[i].idProduct = product;
335 break;
336 }
337 }
338 }
339
340 retval = usb_serial_register(&safe_device);
341 if (retval)
342 goto failed_usb_serial_register;
343 retval = usb_register(&safe_driver);
344 if (retval)
345 goto failed_usb_register;
346
347 return 0;
348failed_usb_register:
349 usb_serial_deregister(&safe_device);
350failed_usb_serial_register:
351 return retval;
352}
353
354static void __exit safe_exit(void)
355{
356 usb_deregister(&safe_driver);
357 usb_serial_deregister(&safe_device);
358}
359
360module_init(safe_init);
361module_exit(safe_exit);
1/*
2 * Safe Encapsulated USB Serial Driver
3 *
4 * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
5 * Copyright (C) 2001 Lineo
6 * Copyright (C) 2001 Hewlett-Packard
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * By:
14 * Stuart Lynne <sl@lineo.com>, Tom Rushworth <tbr@lineo.com>
15 */
16
17/*
18 * The encapsultaion is designed to overcome difficulties with some USB
19 * hardware.
20 *
21 * While the USB protocol has a CRC over the data while in transit, i.e. while
22 * being carried over the bus, there is no end to end protection. If the
23 * hardware has any problems getting the data into or out of the USB transmit
24 * and receive FIFO's then data can be lost.
25 *
26 * This protocol adds a two byte trailer to each USB packet to specify the
27 * number of bytes of valid data and a 10 bit CRC that will allow the receiver
28 * to verify that the entire USB packet was received without error.
29 *
30 * Because in this case the sender and receiver are the class and function
31 * drivers there is now end to end protection.
32 *
33 * There is an additional option that can be used to force all transmitted
34 * packets to be padded to the maximum packet size. This provides a work
35 * around for some devices which have problems with small USB packets.
36 *
37 * Assuming a packetsize of N:
38 *
39 * 0..N-2 data and optional padding
40 *
41 * N-2 bits 7-2 - number of bytes of valid data
42 * bits 1-0 top two bits of 10 bit CRC
43 * N-1 bottom 8 bits of 10 bit CRC
44 *
45 *
46 * | Data Length | 10 bit CRC |
47 * + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 | 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 +
48 *
49 * The 10 bit CRC is computed across the sent data, followed by the trailer
50 * with the length set and the CRC set to zero. The CRC is then OR'd into
51 * the trailer.
52 *
53 * When received a 10 bit CRC is computed over the entire frame including
54 * the trailer and should be equal to zero.
55 *
56 * Two module parameters are used to control the encapsulation, if both are
57 * turned of the module works as a simple serial device with NO
58 * encapsulation.
59 *
60 * See linux/drivers/usbd/serial_fd for a device function driver
61 * implementation of this.
62 *
63 */
64
65#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
66
67#include <linux/kernel.h>
68#include <linux/errno.h>
69#include <linux/gfp.h>
70#include <linux/tty.h>
71#include <linux/tty_driver.h>
72#include <linux/tty_flip.h>
73#include <linux/module.h>
74#include <linux/spinlock.h>
75#include <linux/uaccess.h>
76#include <linux/usb.h>
77#include <linux/usb/serial.h>
78
79
80#ifndef CONFIG_USB_SERIAL_SAFE_PADDED
81#define CONFIG_USB_SERIAL_SAFE_PADDED 0
82#endif
83
84static bool safe = 1;
85static bool padded = CONFIG_USB_SERIAL_SAFE_PADDED;
86
87#define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com, Johan Hovold <jhovold@gmail.com>"
88#define DRIVER_DESC "USB Safe Encapsulated Serial"
89
90MODULE_AUTHOR(DRIVER_AUTHOR);
91MODULE_DESCRIPTION(DRIVER_DESC);
92MODULE_LICENSE("GPL");
93
94module_param(safe, bool, 0);
95MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
96
97module_param(padded, bool, 0);
98MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
99
100#define CDC_DEVICE_CLASS 0x02
101
102#define CDC_INTERFACE_CLASS 0x02
103#define CDC_INTERFACE_SUBCLASS 0x06
104
105#define LINEO_INTERFACE_CLASS 0xff
106
107#define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01
108#define LINEO_SAFENET_CRC 0x01
109#define LINEO_SAFENET_CRC_PADDED 0x02
110
111#define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02
112#define LINEO_SAFESERIAL_CRC 0x01
113#define LINEO_SAFESERIAL_CRC_PADDED 0x02
114
115
116#define MY_USB_DEVICE(vend, prod, dc, ic, isc) \
117 .match_flags = USB_DEVICE_ID_MATCH_DEVICE | \
118 USB_DEVICE_ID_MATCH_DEV_CLASS | \
119 USB_DEVICE_ID_MATCH_INT_CLASS | \
120 USB_DEVICE_ID_MATCH_INT_SUBCLASS, \
121 .idVendor = (vend), \
122 .idProduct = (prod),\
123 .bDeviceClass = (dc),\
124 .bInterfaceClass = (ic), \
125 .bInterfaceSubClass = (isc),
126
127static const struct usb_device_id id_table[] = {
128 {MY_USB_DEVICE(0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Itsy */
129 {MY_USB_DEVICE(0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Calypso */
130 {MY_USB_DEVICE(0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Iris */
131 {MY_USB_DEVICE(0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
132 {MY_USB_DEVICE(0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
133 {MY_USB_DEVICE(0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
134 {MY_USB_DEVICE(0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Sharp tmp */
135 {} /* terminating entry */
136};
137
138MODULE_DEVICE_TABLE(usb, id_table);
139
140static const __u16 crc10_table[256] = {
141 0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff,
142 0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
143 0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce,
144 0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
145 0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d,
146 0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
147 0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac,
148 0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
149 0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b,
150 0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
151 0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a,
152 0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
153 0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259,
154 0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
155 0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268,
156 0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
157 0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377,
158 0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
159 0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346,
160 0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
161 0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315,
162 0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
163 0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324,
164 0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
165 0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3,
166 0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
167 0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382,
168 0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
169 0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1,
170 0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
171 0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0,
172 0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
173};
174
175#define CRC10_INITFCS 0x000 /* Initial FCS value */
176#define CRC10_GOODFCS 0x000 /* Good final FCS value */
177#define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
178
179/**
180 * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
181 * @sp: pointer to buffer
182 * @len: number of bytes
183 * @fcs: starting FCS
184 *
185 * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
186 * new 10 bit FCS.
187 */
188static __u16 __inline__ fcs_compute10(unsigned char *sp, int len, __u16 fcs)
189{
190 for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++));
191 return fcs;
192}
193
194static void safe_process_read_urb(struct urb *urb)
195{
196 struct usb_serial_port *port = urb->context;
197 unsigned char *data = urb->transfer_buffer;
198 unsigned char length = urb->actual_length;
199 int actual_length;
200 __u16 fcs;
201
202 if (!length)
203 return;
204
205 if (!safe)
206 goto out;
207
208 fcs = fcs_compute10(data, length, CRC10_INITFCS);
209 if (fcs) {
210 dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);
211 return;
212 }
213
214 actual_length = data[length - 2] >> 2;
215 if (actual_length > (length - 2)) {
216 dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n",
217 __func__, actual_length, length);
218 return;
219 }
220 dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length);
221 length = actual_length;
222out:
223 tty_insert_flip_string(&port->port, data, length);
224 tty_flip_buffer_push(&port->port);
225}
226
227static int safe_prepare_write_buffer(struct usb_serial_port *port,
228 void *dest, size_t size)
229{
230 unsigned char *buf = dest;
231 int count;
232 int trailer_len;
233 int pkt_len;
234 __u16 fcs;
235
236 trailer_len = safe ? 2 : 0;
237
238 count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len,
239 &port->lock);
240 if (!safe)
241 return count;
242
243 /* pad if necessary */
244 if (padded) {
245 pkt_len = size;
246 memset(buf + count, '0', pkt_len - count - trailer_len);
247 } else {
248 pkt_len = count + trailer_len;
249 }
250
251 /* set count */
252 buf[pkt_len - 2] = count << 2;
253 buf[pkt_len - 1] = 0;
254
255 /* compute fcs and insert into trailer */
256 fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS);
257 buf[pkt_len - 2] |= fcs >> 8;
258 buf[pkt_len - 1] |= fcs & 0xff;
259
260 return pkt_len;
261}
262
263static int safe_startup(struct usb_serial *serial)
264{
265 struct usb_interface_descriptor *desc;
266
267 if (serial->dev->descriptor.bDeviceClass != CDC_DEVICE_CLASS)
268 return -ENODEV;
269
270 desc = &serial->interface->cur_altsetting->desc;
271
272 if (desc->bInterfaceClass != LINEO_INTERFACE_CLASS)
273 return -ENODEV;
274 if (desc->bInterfaceSubClass != LINEO_INTERFACE_SUBCLASS_SAFESERIAL)
275 return -ENODEV;
276
277 switch (desc->bInterfaceProtocol) {
278 case LINEO_SAFESERIAL_CRC:
279 break;
280 case LINEO_SAFESERIAL_CRC_PADDED:
281 padded = 1;
282 break;
283 default:
284 return -EINVAL;
285 }
286 return 0;
287}
288
289static struct usb_serial_driver safe_device = {
290 .driver = {
291 .owner = THIS_MODULE,
292 .name = "safe_serial",
293 },
294 .id_table = id_table,
295 .num_ports = 1,
296 .process_read_urb = safe_process_read_urb,
297 .prepare_write_buffer = safe_prepare_write_buffer,
298 .attach = safe_startup,
299};
300
301static struct usb_serial_driver * const serial_drivers[] = {
302 &safe_device, NULL
303};
304
305module_usb_serial_driver(serial_drivers, id_table);