Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Safe Encapsulated USB Serial Driver | |
3 | * | |
241c80ea | 4 | * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com> |
1da177e4 LT |
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 | ||
43c8f435 AC |
17 | /* |
18 | * The encapsultaion is designed to overcome difficulties with some USB | |
19 | * hardware. | |
1da177e4 LT |
20 | * |
21 | * While the USB protocol has a CRC over the data while in transit, i.e. while | |
43c8f435 AC |
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. | |
1da177e4 | 25 | * |
43c8f435 AC |
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. | |
1da177e4 | 29 | * |
43c8f435 AC |
30 | * Because in this case the sender and receiver are the class and function |
31 | * drivers there is now end to end protection. | |
1da177e4 | 32 | * |
43c8f435 AC |
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. | |
1da177e4 LT |
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 | * | |
43c8f435 AC |
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. | |
1da177e4 | 52 | * |
43c8f435 AC |
53 | * When received a 10 bit CRC is computed over the entire frame including |
54 | * the trailer and should be equal to zero. | |
1da177e4 LT |
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 | ||
93ba0f03 | 65 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
1da177e4 | 66 | |
1da177e4 LT |
67 | #include <linux/kernel.h> |
68 | #include <linux/errno.h> | |
5a0e3ad6 | 69 | #include <linux/gfp.h> |
1da177e4 LT |
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> | |
43c8f435 | 75 | #include <linux/uaccess.h> |
1da177e4 | 76 | #include <linux/usb.h> |
a969888c | 77 | #include <linux/usb/serial.h> |
1da177e4 | 78 | |
ce9d8562 MO |
79 | static bool safe = true; |
80 | static bool padded = IS_ENABLED(CONFIG_USB_SERIAL_SAFE_PADDED); | |
1da177e4 | 81 | |
241c80ea | 82 | #define DRIVER_AUTHOR "sl@lineo.com, tbr@lineo.com, Johan Hovold <jhovold@gmail.com>" |
1da177e4 LT |
83 | #define DRIVER_DESC "USB Safe Encapsulated Serial" |
84 | ||
43c8f435 AC |
85 | MODULE_AUTHOR(DRIVER_AUTHOR); |
86 | MODULE_DESCRIPTION(DRIVER_DESC); | |
1da177e4 LT |
87 | MODULE_LICENSE("GPL"); |
88 | ||
1da177e4 LT |
89 | module_param(safe, bool, 0); |
90 | MODULE_PARM_DESC(safe, "Turn Safe Encapsulation On/Off"); | |
91 | ||
92 | module_param(padded, bool, 0); | |
93 | MODULE_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 | ||
43c8f435 AC |
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), | |
1da177e4 | 121 | |
5c6b98dd | 122 | static const struct usb_device_id id_table[] = { |
43c8f435 AC |
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 */ | |
43c8f435 | 130 | {} /* terminating entry */ |
1da177e4 LT |
131 | }; |
132 | ||
43c8f435 | 133 | MODULE_DEVICE_TABLE(usb, id_table); |
1da177e4 | 134 | |
4c4c9432 | 135 | static const __u16 crc10_table[256] = { |
43c8f435 AC |
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, | |
1da177e4 LT |
168 | }; |
169 | ||
43c8f435 AC |
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)) | |
1da177e4 | 173 | |
43c8f435 | 174 | /** |
1da177e4 LT |
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 | */ | |
43c8f435 | 183 | static __u16 __inline__ fcs_compute10(unsigned char *sp, int len, __u16 fcs) |
1da177e4 | 184 | { |
43c8f435 | 185 | for (; len-- > 0; fcs = CRC10_FCS(fcs, *sp++)); |
1da177e4 LT |
186 | return fcs; |
187 | } | |
188 | ||
12e2e52c | 189 | static void safe_process_read_urb(struct urb *urb) |
1da177e4 | 190 | { |
12e2e52c | 191 | struct usb_serial_port *port = urb->context; |
1da177e4 LT |
192 | unsigned char *data = urb->transfer_buffer; |
193 | unsigned char length = urb->actual_length; | |
6d1bf48e | 194 | int actual_length; |
6d1bf48e | 195 | __u16 fcs; |
1da177e4 | 196 | |
12e2e52c | 197 | if (!length) |
1da177e4 | 198 | return; |
1da177e4 | 199 | |
6d1bf48e JH |
200 | if (!safe) |
201 | goto out; | |
202 | ||
203 | fcs = fcs_compute10(data, length, CRC10_INITFCS); | |
204 | if (fcs) { | |
205 | dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs); | |
2e124b4a | 206 | return; |
1da177e4 LT |
207 | } |
208 | ||
6d1bf48e JH |
209 | actual_length = data[length - 2] >> 2; |
210 | if (actual_length > (length - 2)) { | |
211 | dev_err(&port->dev, "%s - inconsistent lengths %d:%d\n", | |
212 | __func__, actual_length, length); | |
2e124b4a | 213 | return; |
6d1bf48e JH |
214 | } |
215 | dev_info(&urb->dev->dev, "%s - actual: %d\n", __func__, actual_length); | |
216 | length = actual_length; | |
217 | out: | |
05c7cd39 | 218 | tty_insert_flip_string(&port->port, data, length); |
2e124b4a | 219 | tty_flip_buffer_push(&port->port); |
1da177e4 LT |
220 | } |
221 | ||
241c80ea JH |
222 | static int safe_prepare_write_buffer(struct usb_serial_port *port, |
223 | void *dest, size_t size) | |
1da177e4 | 224 | { |
241c80ea JH |
225 | unsigned char *buf = dest; |
226 | int count; | |
227 | int trailer_len; | |
228 | int pkt_len; | |
229 | __u16 fcs; | |
230 | ||
231 | trailer_len = safe ? 2 : 0; | |
232 | ||
233 | count = kfifo_out_locked(&port->write_fifo, buf, size - trailer_len, | |
234 | &port->lock); | |
235 | if (!safe) | |
236 | return count; | |
237 | ||
238 | /* pad if necessary */ | |
239 | if (padded) { | |
240 | pkt_len = size; | |
241 | memset(buf + count, '0', pkt_len - count - trailer_len); | |
1da177e4 | 242 | } else { |
241c80ea | 243 | pkt_len = count + trailer_len; |
1da177e4 | 244 | } |
1da177e4 | 245 | |
241c80ea JH |
246 | /* set count */ |
247 | buf[pkt_len - 2] = count << 2; | |
248 | buf[pkt_len - 1] = 0; | |
1da177e4 | 249 | |
241c80ea JH |
250 | /* compute fcs and insert into trailer */ |
251 | fcs = fcs_compute10(buf, pkt_len, CRC10_INITFCS); | |
252 | buf[pkt_len - 2] |= fcs >> 8; | |
253 | buf[pkt_len - 1] |= fcs & 0xff; | |
1da177e4 | 254 | |
241c80ea | 255 | return pkt_len; |
1da177e4 LT |
256 | } |
257 | ||
43c8f435 | 258 | static int safe_startup(struct usb_serial *serial) |
1da177e4 | 259 | { |
8b61d927 JH |
260 | struct usb_interface_descriptor *desc; |
261 | ||
262 | if (serial->dev->descriptor.bDeviceClass != CDC_DEVICE_CLASS) | |
263 | return -ENODEV; | |
264 | ||
265 | desc = &serial->interface->cur_altsetting->desc; | |
266 | ||
267 | if (desc->bInterfaceClass != LINEO_INTERFACE_CLASS) | |
268 | return -ENODEV; | |
269 | if (desc->bInterfaceSubClass != LINEO_INTERFACE_SUBCLASS_SAFESERIAL) | |
270 | return -ENODEV; | |
271 | ||
272 | switch (desc->bInterfaceProtocol) { | |
1da177e4 LT |
273 | case LINEO_SAFESERIAL_CRC: |
274 | break; | |
275 | case LINEO_SAFESERIAL_CRC_PADDED: | |
ce9d8562 | 276 | padded = true; |
1da177e4 LT |
277 | break; |
278 | default: | |
279 | return -EINVAL; | |
280 | } | |
281 | return 0; | |
282 | } | |
283 | ||
ea65370d | 284 | static struct usb_serial_driver safe_device = { |
18fcac35 GKH |
285 | .driver = { |
286 | .owner = THIS_MODULE, | |
269bda1c | 287 | .name = "safe_serial", |
18fcac35 | 288 | }, |
1da177e4 | 289 | .id_table = id_table, |
1da177e4 | 290 | .num_ports = 1, |
12e2e52c | 291 | .process_read_urb = safe_process_read_urb, |
241c80ea | 292 | .prepare_write_buffer = safe_prepare_write_buffer, |
1da177e4 LT |
293 | .attach = safe_startup, |
294 | }; | |
295 | ||
d860322f AS |
296 | static struct usb_serial_driver * const serial_drivers[] = { |
297 | &safe_device, NULL | |
298 | }; | |
299 | ||
8b61d927 | 300 | module_usb_serial_driver(serial_drivers, id_table); |