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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Safe Encapsulated USB Serial Driver
4 *
5 * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
6 * Copyright (C) 2001 Lineo
7 * Copyright (C) 2001 Hewlett-Packard
8 *
9 * By:
10 * Stuart Lynne <sl@lineo.com>, Tom Rushworth <tbr@lineo.com>
11 */
12
13/*
14 * The encapsultaion is designed to overcome difficulties with some USB
15 * hardware.
16 *
17 * While the USB protocol has a CRC over the data while in transit, i.e. while
18 * being carried over the bus, there is no end to end protection. If the
19 * hardware has any problems getting the data into or out of the USB transmit
20 * and receive FIFO's then data can be lost.
21 *
22 * This protocol adds a two byte trailer to each USB packet to specify the
23 * number of bytes of valid data and a 10 bit CRC that will allow the receiver
24 * to verify that the entire USB packet was received without error.
25 *
26 * Because in this case the sender and receiver are the class and function
27 * drivers there is now end to end protection.
28 *
29 * There is an additional option that can be used to force all transmitted
30 * packets to be padded to the maximum packet size. This provides a work
31 * around for some devices which have problems with small USB packets.
32 *
33 * Assuming a packetsize of N:
34 *
35 * 0..N-2 data and optional padding
36 *
37 * N-2 bits 7-2 - number of bytes of valid data
38 * bits 1-0 top two bits of 10 bit CRC
39 * N-1 bottom 8 bits of 10 bit CRC
40 *
41 *
42 * | Data Length | 10 bit CRC |
43 * + 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 | 7 . 6 . 5 . 4 . 3 . 2 . 1 . 0 +
44 *
45 * The 10 bit CRC is computed across the sent data, followed by the trailer
46 * with the length set and the CRC set to zero. The CRC is then OR'd into
47 * the trailer.
48 *
49 * When received a 10 bit CRC is computed over the entire frame including
50 * the trailer and should be equal to zero.
51 *
52 * Two module parameters are used to control the encapsulation, if both are
53 * turned of the module works as a simple serial device with NO
54 * encapsulation.
55 *
56 * See linux/drivers/usbd/serial_fd for a device function driver
57 * implementation of this.
58 *
59 */
60
61#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
62
63#include <linux/kernel.h>
64#include <linux/errno.h>
65#include <linux/gfp.h>
66#include <linux/tty.h>
67#include <linux/tty_driver.h>
68#include <linux/tty_flip.h>
69#include <linux/module.h>
70#include <linux/spinlock.h>
71#include <linux/uaccess.h>
72#include <linux/usb.h>
73#include <linux/usb/serial.h>
74
75static bool safe = true;
76static bool padded = IS_ENABLED(CONFIG_USB_SERIAL_SAFE_PADDED);
77
78#define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com, Johan Hovold <jhovold@gmail.com>"
79#define DRIVER_DESC "USB Safe Encapsulated Serial"
80
81MODULE_AUTHOR(DRIVER_AUTHOR);
82MODULE_DESCRIPTION(DRIVER_DESC);
83MODULE_LICENSE("GPL");
84
85module_param(safe, bool, 0);
86MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off");
87
88module_param(padded, bool, 0);
89MODULE_PARM_DESC(padded, "Pad to full wMaxPacketSize On/Off");
90
91#define CDC_DEVICE_CLASS 0x02
92
93#define CDC_INTERFACE_CLASS 0x02
94#define CDC_INTERFACE_SUBCLASS 0x06
95
96#define LINEO_INTERFACE_CLASS 0xff
97
98#define LINEO_INTERFACE_SUBCLASS_SAFENET 0x01
99#define LINEO_SAFENET_CRC 0x01
100#define LINEO_SAFENET_CRC_PADDED 0x02
101
102#define LINEO_INTERFACE_SUBCLASS_SAFESERIAL 0x02
103#define LINEO_SAFESERIAL_CRC 0x01
104#define LINEO_SAFESERIAL_CRC_PADDED 0x02
105
106
107#define MY_USB_DEVICE(vend, prod, dc, ic, isc) \
108 .match_flags = USB_DEVICE_ID_MATCH_DEVICE | \
109 USB_DEVICE_ID_MATCH_DEV_CLASS | \
110 USB_DEVICE_ID_MATCH_INT_CLASS | \
111 USB_DEVICE_ID_MATCH_INT_SUBCLASS, \
112 .idVendor = (vend), \
113 .idProduct = (prod),\
114 .bDeviceClass = (dc),\
115 .bInterfaceClass = (ic), \
116 .bInterfaceSubClass = (isc),
117
118static const struct usb_device_id id_table[] = {
119 {MY_USB_DEVICE(0x49f, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Itsy */
120 {MY_USB_DEVICE(0x3f0, 0x2101, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Calypso */
121 {MY_USB_DEVICE(0x4dd, 0x8001, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Iris */
122 {MY_USB_DEVICE(0x4dd, 0x8002, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
123 {MY_USB_DEVICE(0x4dd, 0x8003, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
124 {MY_USB_DEVICE(0x4dd, 0x8004, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Collie */
125 {MY_USB_DEVICE(0x5f9, 0xffff, CDC_DEVICE_CLASS, LINEO_INTERFACE_CLASS, LINEO_INTERFACE_SUBCLASS_SAFESERIAL)}, /* Sharp tmp */
126 {} /* terminating entry */
127};
128
129MODULE_DEVICE_TABLE(usb, id_table);
130
131static const __u16 crc10_table[256] = {
132 0x000, 0x233, 0x255, 0x066, 0x299, 0x0aa, 0x0cc, 0x2ff,
133 0x301, 0x132, 0x154, 0x367, 0x198, 0x3ab, 0x3cd, 0x1fe,
134 0x031, 0x202, 0x264, 0x057, 0x2a8, 0x09b, 0x0fd, 0x2ce,
135 0x330, 0x103, 0x165, 0x356, 0x1a9, 0x39a, 0x3fc, 0x1cf,
136 0x062, 0x251, 0x237, 0x004, 0x2fb, 0x0c8, 0x0ae, 0x29d,
137 0x363, 0x150, 0x136, 0x305, 0x1fa, 0x3c9, 0x3af, 0x19c,
138 0x053, 0x260, 0x206, 0x035, 0x2ca, 0x0f9, 0x09f, 0x2ac,
139 0x352, 0x161, 0x107, 0x334, 0x1cb, 0x3f8, 0x39e, 0x1ad,
140 0x0c4, 0x2f7, 0x291, 0x0a2, 0x25d, 0x06e, 0x008, 0x23b,
141 0x3c5, 0x1f6, 0x190, 0x3a3, 0x15c, 0x36f, 0x309, 0x13a,
142 0x0f5, 0x2c6, 0x2a0, 0x093, 0x26c, 0x05f, 0x039, 0x20a,
143 0x3f4, 0x1c7, 0x1a1, 0x392, 0x16d, 0x35e, 0x338, 0x10b,
144 0x0a6, 0x295, 0x2f3, 0x0c0, 0x23f, 0x00c, 0x06a, 0x259,
145 0x3a7, 0x194, 0x1f2, 0x3c1, 0x13e, 0x30d, 0x36b, 0x158,
146 0x097, 0x2a4, 0x2c2, 0x0f1, 0x20e, 0x03d, 0x05b, 0x268,
147 0x396, 0x1a5, 0x1c3, 0x3f0, 0x10f, 0x33c, 0x35a, 0x169,
148 0x188, 0x3bb, 0x3dd, 0x1ee, 0x311, 0x122, 0x144, 0x377,
149 0x289, 0x0ba, 0x0dc, 0x2ef, 0x010, 0x223, 0x245, 0x076,
150 0x1b9, 0x38a, 0x3ec, 0x1df, 0x320, 0x113, 0x175, 0x346,
151 0x2b8, 0x08b, 0x0ed, 0x2de, 0x021, 0x212, 0x274, 0x047,
152 0x1ea, 0x3d9, 0x3bf, 0x18c, 0x373, 0x140, 0x126, 0x315,
153 0x2eb, 0x0d8, 0x0be, 0x28d, 0x072, 0x241, 0x227, 0x014,
154 0x1db, 0x3e8, 0x38e, 0x1bd, 0x342, 0x171, 0x117, 0x324,
155 0x2da, 0x0e9, 0x08f, 0x2bc, 0x043, 0x270, 0x216, 0x025,
156 0x14c, 0x37f, 0x319, 0x12a, 0x3d5, 0x1e6, 0x180, 0x3b3,
157 0x24d, 0x07e, 0x018, 0x22b, 0x0d4, 0x2e7, 0x281, 0x0b2,
158 0x17d, 0x34e, 0x328, 0x11b, 0x3e4, 0x1d7, 0x1b1, 0x382,
159 0x27c, 0x04f, 0x029, 0x21a, 0x0e5, 0x2d6, 0x2b0, 0x083,
160 0x12e, 0x31d, 0x37b, 0x148, 0x3b7, 0x184, 0x1e2, 0x3d1,
161 0x22f, 0x01c, 0x07a, 0x249, 0x0b6, 0x285, 0x2e3, 0x0d0,
162 0x11f, 0x32c, 0x34a, 0x179, 0x386, 0x1b5, 0x1d3, 0x3e0,
163 0x21e, 0x02d, 0x04b, 0x278, 0x087, 0x2b4, 0x2d2, 0x0e1,
164};
165
166#define CRC10_INITFCS 0x000 /* Initial FCS value */
167#define CRC10_GOODFCS 0x000 /* Good final FCS value */
168#define CRC10_FCS(fcs, c) ((((fcs) << 8) & 0x3ff) ^ crc10_table[((fcs) >> 2) & 0xff] ^ (c))
169
170/**
171 * fcs_compute10 - memcpy and calculate 10 bit CRC across buffer
172 * @sp: pointer to buffer
173 * @len: number of bytes
174 * @fcs: starting FCS
175 *
176 * Perform a memcpy and calculate fcs using ppp 10bit CRC algorithm. Return
177 * new 10 bit FCS.
178 */
179static inline __u16 fcs_compute10(unsigned char *sp, int len, __u16 fcs)
180{
181 for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++));
182 return fcs;
183}
184
185static void safe_process_read_urb(struct urb *urb)
186{
187 struct usb_serial_port *port = urb->context;
188 unsigned char *data = urb->transfer_buffer;
189 unsigned char length = urb->actual_length;
190 int actual_length;
191 __u16 fcs;
192
193 if (!length)
194 return;
195
196 if (!safe)
197 goto out;
198
199 if (length < 2) {
200 dev_err(&port->dev, "malformed packet\n");
201 return;
202 }
203
204 fcs = fcs_compute10(data, length, CRC10_INITFCS);
205 if (fcs) {
206 dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);
207 return;
208 }
209
210 actual_length = data[length - 2] >> 2;
211 if (actual_length > (length - 2)) {
212 dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n",
213 __func__, actual_length, length);
214 return;
215 }
216 dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length);
217 length = actual_length;
218out:
219 tty_insert_flip_string(&port->port, data, length);
220 tty_flip_buffer_push(&port->port);
221}
222
223static int safe_prepare_write_buffer(struct usb_serial_port *port,
224 void *dest, size_t size)
225{
226 unsigned char *buf = dest;
227 int count;
228 int trailer_len;
229 int pkt_len;
230 __u16 fcs;
231
232 trailer_len = safe ? 2 : 0;
233
234 count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len,
235 &port->lock);
236 if (!safe)
237 return count;
238
239 /* pad if necessary */
240 if (padded) {
241 pkt_len = size;
242 memset(buf + count, '0', pkt_len - count - trailer_len);
243 } else {
244 pkt_len = count + trailer_len;
245 }
246
247 /* set count */
248 buf[pkt_len - 2] = count << 2;
249 buf[pkt_len - 1] = 0;
250
251 /* compute fcs and insert into trailer */
252 fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS);
253 buf[pkt_len - 2] |= fcs >> 8;
254 buf[pkt_len - 1] |= fcs & 0xff;
255
256 return pkt_len;
257}
258
259static int safe_startup(struct usb_serial *serial)
260{
261 struct usb_interface_descriptor *desc;
262
263 if (serial->dev->descriptor.bDeviceClass != CDC_DEVICE_CLASS)
264 return -ENODEV;
265
266 desc = &serial->interface->cur_altsetting->desc;
267
268 if (desc->bInterfaceClass != LINEO_INTERFACE_CLASS)
269 return -ENODEV;
270 if (desc->bInterfaceSubClass != LINEO_INTERFACE_SUBCLASS_SAFESERIAL)
271 return -ENODEV;
272
273 switch (desc->bInterfaceProtocol) {
274 case LINEO_SAFESERIAL_CRC:
275 break;
276 case LINEO_SAFESERIAL_CRC_PADDED:
277 padded = true;
278 break;
279 default:
280 return -EINVAL;
281 }
282 return 0;
283}
284
285static struct usb_serial_driver safe_device = {
286 .driver = {
287 .owner = THIS_MODULE,
288 .name = "safe_serial",
289 },
290 .id_table = id_table,
291 .num_ports = 1,
292 .process_read_urb = safe_process_read_urb,
293 .prepare_write_buffer = safe_prepare_write_buffer,
294 .attach = safe_startup,
295};
296
297static struct usb_serial_driver * const serial_drivers[] = {
298 &safe_device, NULL
299};
300
301module_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);