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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#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
79static bool safe = true;
80static bool padded = IS_ENABLED(CONFIG_USB_SERIAL_SAFE_PADDED);
81
82#define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com, Johan Hovold <jhovold@gmail.com>"
83#define DRIVER_DESC "USB Safe Encapsulated Serial"
84
85MODULE_AUTHOR(DRIVER_AUTHOR);
86MODULE_DESCRIPTION(DRIVER_DESC);
87MODULE_LICENSE("GPL");
88
89module_param(safe, bool, 0);
90MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
91
92module_param(padded, bool, 0);
93MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
94
95#define CDC_DEVICE_CLASS 0x02
96
97#define CDC_INTERFACE_CLASS 0x02
98#define CDC_INTERFACE_SUBCLASS 0x06
99
100#define LINEO_INTERFACE_CLASS 0xff
101
102#define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01
103#define LINEO_SAFENET_CRC 0x01
104#define LINEO_SAFENET_CRC_PADDED 0x02
105
106#define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02
107#define LINEO_SAFESERIAL_CRC 0x01
108#define LINEO_SAFESERIAL_CRC_PADDED 0x02
109
110
111#define MY_USB_DEVICE(vend, prod, dc, ic, isc) \
112 .match_flags = USB_DEVICE_ID_MATCH_DEVICE | \
113 USB_DEVICE_ID_MATCH_DEV_CLASS | \
114 USB_DEVICE_ID_MATCH_INT_CLASS | \
115 USB_DEVICE_ID_MATCH_INT_SUBCLASS, \
116 .idVendor = (vend), \
117 .idProduct = (prod),\
118 .bDeviceClass = (dc),\
119 .bInterfaceClass = (ic), \
120 .bInterfaceSubClass = (isc),
121
122static const struct usb_device_id id_table[] = {
123 {MY_USB_DEVICE(0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Itsy */
124 {MY_USB_DEVICE(0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Calypso */
125 {MY_USB_DEVICE(0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Iris */
126 {MY_USB_DEVICE(0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
127 {MY_USB_DEVICE(0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
128 {MY_USB_DEVICE(0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
129 {MY_USB_DEVICE(0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Sharp tmp */
130 {} /* terminating entry */
131};
132
133MODULE_DEVICE_TABLE(usb, id_table);
134
135static const __u16 crc10_table[256] = {
136 0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff,
137 0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
138 0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce,
139 0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
140 0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d,
141 0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
142 0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac,
143 0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
144 0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b,
145 0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
146 0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a,
147 0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
148 0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259,
149 0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
150 0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268,
151 0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
152 0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377,
153 0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
154 0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346,
155 0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
156 0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315,
157 0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
158 0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324,
159 0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
160 0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3,
161 0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
162 0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382,
163 0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
164 0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1,
165 0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
166 0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0,
167 0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
168};
169
170#define CRC10_INITFCS 0x000 /* Initial FCS value */
171#define CRC10_GOODFCS 0x000 /* Good final FCS value */
172#define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
173
174/**
175 * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
176 * @sp: pointer to buffer
177 * @len: number of bytes
178 * @fcs: starting FCS
179 *
180 * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
181 * new 10 bit FCS.
182 */
183static __u16 __inline__ fcs_compute10(unsigned char *sp, int len, __u16 fcs)
184{
185 for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++));
186 return fcs;
187}
188
189static void safe_process_read_urb(struct urb *urb)
190{
191 struct usb_serial_port *port = urb->context;
192 unsigned char *data = urb->transfer_buffer;
193 unsigned char length = urb->actual_length;
194 int actual_length;
195 __u16 fcs;
196
197 if (!length)
198 return;
199
200 if (!safe)
201 goto out;
202
203 if (length < 2) {
204 dev_err(&port->dev, "malformed packet\n");
205 return;
206 }
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 = true;
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);
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 bool debug;
85static bool safe = 1;
86static bool 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 const __u16 crc10_table[256] = {
155 0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff,
156 0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
157 0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce,
158 0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
159 0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d,
160 0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
161 0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac,
162 0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
163 0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b,
164 0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
165 0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a,
166 0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
167 0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259,
168 0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
169 0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268,
170 0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
171 0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377,
172 0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
173 0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346,
174 0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
175 0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315,
176 0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
177 0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324,
178 0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
179 0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3,
180 0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
181 0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382,
182 0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
183 0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1,
184 0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
185 0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0,
186 0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
187};
188
189#define CRC10_INITFCS 0x000 /* Initial FCS value */
190#define CRC10_GOODFCS 0x000 /* Good final FCS value */
191#define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
192
193/**
194 * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
195 * @sp: pointer to buffer
196 * @len: number of bytes
197 * @fcs: starting FCS
198 *
199 * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
200 * new 10 bit FCS.
201 */
202static __u16 __inline__ fcs_compute10(unsigned char *sp, int len, __u16 fcs)
203{
204 for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++));
205 return fcs;
206}
207
208static void safe_process_read_urb(struct urb *urb)
209{
210 struct usb_serial_port *port = urb->context;
211 unsigned char *data = urb->transfer_buffer;
212 unsigned char length = urb->actual_length;
213 int actual_length;
214 struct tty_struct *tty;
215 __u16 fcs;
216
217 if (!length)
218 return;
219
220 tty = tty_port_tty_get(&port->port);
221 if (!tty)
222 return;
223
224 if (!safe)
225 goto out;
226
227 fcs = fcs_compute10(data, length, CRC10_INITFCS);
228 if (fcs) {
229 dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);
230 goto err;
231 }
232
233 actual_length = data[length - 2] >> 2;
234 if (actual_length > (length - 2)) {
235 dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n",
236 __func__, actual_length, length);
237 goto err;
238 }
239 dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length);
240 length = actual_length;
241out:
242 tty_insert_flip_string(tty, data, length);
243 tty_flip_buffer_push(tty);
244err:
245 tty_kref_put(tty);
246}
247
248static int safe_prepare_write_buffer(struct usb_serial_port *port,
249 void *dest, size_t size)
250{
251 unsigned char *buf = dest;
252 int count;
253 int trailer_len;
254 int pkt_len;
255 __u16 fcs;
256
257 trailer_len = safe ? 2 : 0;
258
259 count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len,
260 &port->lock);
261 if (!safe)
262 return count;
263
264 /* pad if necessary */
265 if (padded) {
266 pkt_len = size;
267 memset(buf + count, '0', pkt_len - count - trailer_len);
268 } else {
269 pkt_len = count + trailer_len;
270 }
271
272 /* set count */
273 buf[pkt_len - 2] = count << 2;
274 buf[pkt_len - 1] = 0;
275
276 /* compute fcs and insert into trailer */
277 fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS);
278 buf[pkt_len - 2] |= fcs >> 8;
279 buf[pkt_len - 1] |= fcs & 0xff;
280
281 return pkt_len;
282}
283
284static int safe_startup(struct usb_serial *serial)
285{
286 switch (serial->interface->cur_altsetting->desc.bInterfaceProtocol) {
287 case LINEO_SAFESERIAL_CRC:
288 break;
289 case LINEO_SAFESERIAL_CRC_PADDED:
290 padded = 1;
291 break;
292 default:
293 return -EINVAL;
294 }
295 return 0;
296}
297
298static struct usb_serial_driver safe_device = {
299 .driver = {
300 .owner = THIS_MODULE,
301 .name = "safe_serial",
302 },
303 .id_table = id_table,
304 .num_ports = 1,
305 .process_read_urb = safe_process_read_urb,
306 .prepare_write_buffer = safe_prepare_write_buffer,
307 .attach = safe_startup,
308};
309
310static struct usb_serial_driver * const serial_drivers[] = {
311 &safe_device, NULL
312};
313
314static int __init safe_init(void)
315{
316 int i;
317
318 printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
319 DRIVER_DESC "\n");
320
321 /* if we have vendor / product parameters patch them into id list */
322 if (vendor || product) {
323 printk(KERN_INFO KBUILD_MODNAME ": vendor: %x product: %x\n",
324 vendor, product);
325
326 for (i = 0; i < ARRAY_SIZE(id_table); i++) {
327 if (!id_table[i].idVendor && !id_table[i].idProduct) {
328 id_table[i].idVendor = vendor;
329 id_table[i].idProduct = product;
330 break;
331 }
332 }
333 }
334
335 return usb_serial_register_drivers(serial_drivers, KBUILD_MODNAME, id_table);
336}
337
338static void __exit safe_exit(void)
339{
340 usb_serial_deregister_drivers(serial_drivers);
341}
342
343module_init(safe_init);
344module_exit(safe_exit);