summaryrefslogtreecommitdiff
path: root/drivers/net/usb/kalmia.c
blob: 613fc6910f1481cc89cb5325a5cd12379aebf94a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * USB network interface driver for Samsung Kalmia based LTE USB modem like the
 * Samsung GT-B3730 and GT-B3710.
 *
 * Copyright (C) 2011 Marius Bjoernstad Kotsbak <marius@kotsbak.com>
 *
 * Sponsored by Quicklink Video Distribution Services Ltd.
 *
 * Based on the cdc_eem module.
 */

#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ctype.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/crc32.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/gfp.h>

/*
 * The Samsung Kalmia based LTE USB modems have a CDC ACM port for modem control
 * handled by the "option" module and an ethernet data port handled by this
 * module.
 *
 * The stick must first be switched into modem mode by usb_modeswitch
 * or similar tool. Then the modem gets sent two initialization packets by
 * this module, which gives the MAC address of the device. User space can then
 * connect the modem using AT commands through the ACM port and then use
 * DHCP on the network interface exposed by this module. Network packets are
 * sent to and from the modem in a proprietary format discovered after watching
 * the behavior of the windows driver for the modem.
 *
 * More information about the use of the modem is available in usb_modeswitch
 * forum and the project page:
 *
 * http://www.draisberghof.de/usb_modeswitch/bb/viewtopic.php?t=465
 * https://github.com/mkotsbak/Samsung-GT-B3730-linux-driver
 */

/* #define	DEBUG */
/* #define	VERBOSE */

#define KALMIA_HEADER_LENGTH 6
#define KALMIA_ALIGN_SIZE 4
#define KALMIA_USB_TIMEOUT 10000

/*-------------------------------------------------------------------------*/

static int
kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8 init_msg_len,
	u8 *buffer, u8 expected_len)
{
	int act_len;
	int status;

	netdev_dbg(dev->net, "Sending init packet");

	status = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 0x02),
		init_msg, init_msg_len, &act_len, KALMIA_USB_TIMEOUT);
	if (status != 0) {
		netdev_err(dev->net,
			"Error sending init packet. Status %i\n",
			status);
		return status;
	}
	else if (act_len != init_msg_len) {
		netdev_err(dev->net,
			"Did not send all of init packet. Bytes sent: %i",
			act_len);
	}
	else {
		netdev_dbg(dev->net, "Successfully sent init packet.");
	}

	status = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, 0x81),
		buffer, expected_len, &act_len, KALMIA_USB_TIMEOUT);

	if (status != 0)
		netdev_err(dev->net,
			"Error receiving init result. Status %i\n",
			status);
	else if (act_len != expected_len)
		netdev_err(dev->net, "Unexpected init result length: %i\n",
			act_len);

	return status;
}

static int
kalmia_init_and_get_ethernet_addr(struct usbnet *dev, u8 *ethernet_addr)
{
	static const char init_msg_1[] =
		{ 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
		0x00, 0x00 };
	static const char init_msg_2[] =
		{ 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4,
		0x00, 0x00 };
	static const int buflen = 28;
	char *usb_buf;
	int status;

	usb_buf = kmalloc(buflen, GFP_DMA | GFP_KERNEL);
	if (!usb_buf)
		return -ENOMEM;

	memcpy(usb_buf, init_msg_1, 12);
	status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_1),
					 usb_buf, 24);
	if (status != 0)
		goto out;

	memcpy(usb_buf, init_msg_2, 12);
	status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_2),
					 usb_buf, 28);
	if (status != 0)
		goto out;

	memcpy(ethernet_addr, usb_buf + 10, ETH_ALEN);
out:
	kfree(usb_buf);
	return status;
}

static int
kalmia_bind(struct usbnet *dev, struct usb_interface *intf)
{
	int status;
	u8 ethernet_addr[ETH_ALEN];

	/* Don't bind to AT command interface */
	if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
		return -EINVAL;

	dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK);
	dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK);
	dev->status = NULL;

	dev->net->hard_header_len += KALMIA_HEADER_LENGTH;
	dev->hard_mtu = 1400;
	dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing

	status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr);
	if (status)
		return status;

	eth_hw_addr_set(dev->net, ethernet_addr);

	return status;
}

static struct sk_buff *
kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
	struct sk_buff *skb2 = NULL;
	u16 content_len;
	unsigned char *header_start;
	unsigned char ether_type_1, ether_type_2;
	u8 remainder, padlen = 0;

	if (!skb_cloned(skb)) {
		int headroom = skb_headroom(skb);
		int tailroom = skb_tailroom(skb);

		if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom
			>= KALMIA_HEADER_LENGTH))
			goto done;

		if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH
			+ KALMIA_ALIGN_SIZE)) {
			skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH,
				skb->data, skb->len);
			skb_set_tail_pointer(skb, skb->len);
			goto done;
		}
	}

	skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH,
		KALMIA_ALIGN_SIZE, flags);
	if (!skb2)
		return NULL;

	dev_kfree_skb_any(skb);
	skb = skb2;

done:
	header_start = skb_push(skb, KALMIA_HEADER_LENGTH);
	ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12];
	ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13];

	netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1,
		ether_type_2);

	/* According to empiric data for data packages */
	header_start[0] = 0x57;
	header_start[1] = 0x44;
	content_len = skb->len - KALMIA_HEADER_LENGTH;

	put_unaligned_le16(content_len, &header_start[2]);
	header_start[4] = ether_type_1;
	header_start[5] = ether_type_2;

	/* Align to 4 bytes by padding with zeros */
	remainder = skb->len % KALMIA_ALIGN_SIZE;
	if (remainder > 0) {
		padlen = KALMIA_ALIGN_SIZE - remainder;
		skb_put_zero(skb, padlen);
	}

	netdev_dbg(dev->net,
		"Sending package with length %i and padding %i. Header: %6phC.",
		content_len, padlen, header_start);

	return skb;
}

static int
kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
	/*
	 * Our task here is to strip off framing, leaving skb with one
	 * data frame for the usbnet framework code to process.
	 */
	static const u8 HEADER_END_OF_USB_PACKET[] =
		{ 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 };
	static const u8 EXPECTED_UNKNOWN_HEADER_1[] =
		{ 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 };
	static const u8 EXPECTED_UNKNOWN_HEADER_2[] =
		{ 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 };
	int i = 0;

	/* incomplete header? */
	if (skb->len < KALMIA_HEADER_LENGTH)
		return 0;

	do {
		struct sk_buff *skb2 = NULL;
		u8 *header_start;
		u16 usb_packet_length, ether_packet_length;
		int is_last;

		header_start = skb->data;

		if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) {
			if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1,
				sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp(
				header_start, EXPECTED_UNKNOWN_HEADER_2,
				sizeof(EXPECTED_UNKNOWN_HEADER_2))) {
				netdev_dbg(dev->net,
					"Received expected unknown frame header: %6phC. Package length: %i\n",
					header_start,
					skb->len - KALMIA_HEADER_LENGTH);
			}
			else {
				netdev_err(dev->net,
					"Received unknown frame header: %6phC. Package length: %i\n",
					header_start,
					skb->len - KALMIA_HEADER_LENGTH);
				return 0;
			}
		}
		else
			netdev_dbg(dev->net,
				"Received header: %6phC. Package length: %i\n",
				header_start, skb->len - KALMIA_HEADER_LENGTH);

		/* subtract start header and end header */
		usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH);
		ether_packet_length = get_unaligned_le16(&header_start[2]);
		skb_pull(skb, KALMIA_HEADER_LENGTH);

		/* Some small packets misses end marker */
		if (usb_packet_length < ether_packet_length) {
			ether_packet_length = usb_packet_length
				+ KALMIA_HEADER_LENGTH;
			is_last = true;
		}
		else {
			netdev_dbg(dev->net, "Correct package length #%i", i
				+ 1);

			is_last = (memcmp(skb->data + ether_packet_length,
				HEADER_END_OF_USB_PACKET,
				sizeof(HEADER_END_OF_USB_PACKET)) == 0);
			if (!is_last) {
				header_start = skb->data + ether_packet_length;
				netdev_dbg(dev->net,
					"End header: %6phC. Package length: %i\n",
					header_start,
					skb->len - KALMIA_HEADER_LENGTH);
			}
		}

		if (is_last) {
			skb2 = skb;
		}
		else {
			skb2 = skb_clone(skb, GFP_ATOMIC);
			if (unlikely(!skb2))
				return 0;
		}

		skb_trim(skb2, ether_packet_length);

		if (is_last) {
			return 1;
		}
		else {
			usbnet_skb_return(dev, skb2);
			skb_pull(skb, ether_packet_length);
		}

		i++;
	}
	while (skb->len);

	return 1;
}

static const struct driver_info kalmia_info = {
	.description = "Samsung Kalmia LTE USB dongle",
	.flags = FLAG_WWAN,
	.bind = kalmia_bind,
	.rx_fixup = kalmia_rx_fixup,
	.tx_fixup = kalmia_tx_fixup
};

/*-------------------------------------------------------------------------*/

static const struct usb_device_id products[] = {
	/* The unswitched USB ID, to get the module auto loaded: */
	{ USB_DEVICE(0x04e8, 0x689a) },
	/* The stick switched into modem (by e.g. usb_modeswitch): */
	{ USB_DEVICE(0x04e8, 0x6889),
		.driver_info = (unsigned long) &kalmia_info, },
	{ /* EMPTY == end of list */} };
MODULE_DEVICE_TABLE( usb, products);

static struct usb_driver kalmia_driver = {
	.name = "kalmia",
	.id_table = products,
	.probe = usbnet_probe,
	.disconnect = usbnet_disconnect,
	.suspend = usbnet_suspend,
	.resume = usbnet_resume,
	.disable_hub_initiated_lpm = 1,
};

module_usb_driver(kalmia_driver);

MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>");
MODULE_DESCRIPTION("Samsung Kalmia USB network driver");
MODULE_LICENSE("GPL");