1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * USB network interface driver for Samsung Kalmia based LTE USB modem like the
4 * Samsung GT-B3730 and GT-B3710.
5 *
6 * Copyright (C) 2011 Marius Bjoernstad Kotsbak <marius@kotsbak.com>
7 *
8 * Sponsored by Quicklink Video Distribution Services Ltd.
9 *
10 * Based on the cdc_eem module.
11 */
12
13 #include <linux/module.h>
14 #include <linux/netdevice.h>
15 #include <linux/etherdevice.h>
16 #include <linux/ctype.h>
17 #include <linux/ethtool.h>
18 #include <linux/workqueue.h>
19 #include <linux/mii.h>
20 #include <linux/usb.h>
21 #include <linux/crc32.h>
22 #include <linux/usb/cdc.h>
23 #include <linux/usb/usbnet.h>
24 #include <linux/gfp.h>
25
26 /*
27 * The Samsung Kalmia based LTE USB modems have a CDC ACM port for modem control
28 * handled by the "option" module and an ethernet data port handled by this
29 * module.
30 *
31 * The stick must first be switched into modem mode by usb_modeswitch
32 * or similar tool. Then the modem gets sent two initialization packets by
33 * this module, which gives the MAC address of the device. User space can then
34 * connect the modem using AT commands through the ACM port and then use
35 * DHCP on the network interface exposed by this module. Network packets are
36 * sent to and from the modem in a proprietary format discovered after watching
37 * the behavior of the windows driver for the modem.
38 *
39 * More information about the use of the modem is available in usb_modeswitch
40 * forum and the project page:
41 *
42 * http://www.draisberghof.de/usb_modeswitch/bb/viewtopic.php?t=465
43 * https://github.com/mkotsbak/Samsung-GT-B3730-linux-driver
44 */
45
46 /* #define DEBUG */
47 /* #define VERBOSE */
48
49 #define KALMIA_HEADER_LENGTH 6
50 #define KALMIA_ALIGN_SIZE 4
51 #define KALMIA_USB_TIMEOUT 10000
52
53 /*-------------------------------------------------------------------------*/
54
55 static int
kalmia_send_init_packet(struct usbnet * dev,u8 * init_msg,u8 init_msg_len,u8 * buffer,u8 expected_len)56 kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8 init_msg_len,
57 u8 *buffer, u8 expected_len)
58 {
59 int act_len;
60 int status;
61
62 netdev_dbg(dev->net, "Sending init packet");
63
64 status = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 0x02),
65 init_msg, init_msg_len, &act_len, KALMIA_USB_TIMEOUT);
66 if (status != 0) {
67 netdev_err(dev->net,
68 "Error sending init packet. Status %i, length %i\n",
69 status, act_len);
70 return status;
71 }
72 else if (act_len != init_msg_len) {
73 netdev_err(dev->net,
74 "Did not send all of init packet. Bytes sent: %i",
75 act_len);
76 }
77 else {
78 netdev_dbg(dev->net, "Successfully sent init packet.");
79 }
80
81 status = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, 0x81),
82 buffer, expected_len, &act_len, KALMIA_USB_TIMEOUT);
83
84 if (status != 0)
85 netdev_err(dev->net,
86 "Error receiving init result. Status %i, length %i\n",
87 status, act_len);
88 else if (act_len != expected_len)
89 netdev_err(dev->net, "Unexpected init result length: %i\n",
90 act_len);
91
92 return status;
93 }
94
95 static int
kalmia_init_and_get_ethernet_addr(struct usbnet * dev,u8 * ethernet_addr)96 kalmia_init_and_get_ethernet_addr(struct usbnet *dev, u8 *ethernet_addr)
97 {
98 static const char init_msg_1[] =
99 { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
100 0x00, 0x00 };
101 static const char init_msg_2[] =
102 { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4,
103 0x00, 0x00 };
104 static const int buflen = 28;
105 char *usb_buf;
106 int status;
107
108 usb_buf = kmalloc(buflen, GFP_DMA | GFP_KERNEL);
109 if (!usb_buf)
110 return -ENOMEM;
111
112 memcpy(usb_buf, init_msg_1, 12);
113 status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_1),
114 usb_buf, 24);
115 if (status != 0)
116 goto out;
117
118 memcpy(usb_buf, init_msg_2, 12);
119 status = kalmia_send_init_packet(dev, usb_buf, ARRAY_SIZE(init_msg_2),
120 usb_buf, 28);
121 if (status != 0)
122 goto out;
123
124 memcpy(ethernet_addr, usb_buf + 10, ETH_ALEN);
125 out:
126 kfree(usb_buf);
127 return status;
128 }
129
130 static int
kalmia_bind(struct usbnet * dev,struct usb_interface * intf)131 kalmia_bind(struct usbnet *dev, struct usb_interface *intf)
132 {
133 int status;
134 u8 ethernet_addr[ETH_ALEN];
135
136 /* Don't bind to AT command interface */
137 if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
138 return -EINVAL;
139
140 dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK);
141 dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK);
142 dev->status = NULL;
143
144 dev->net->hard_header_len += KALMIA_HEADER_LENGTH;
145 dev->hard_mtu = 1400;
146 dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing
147
148 status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr);
149 if (status)
150 return status;
151
152 memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN);
153
154 return status;
155 }
156
157 static struct sk_buff *
kalmia_tx_fixup(struct usbnet * dev,struct sk_buff * skb,gfp_t flags)158 kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
159 {
160 struct sk_buff *skb2 = NULL;
161 u16 content_len;
162 unsigned char *header_start;
163 unsigned char ether_type_1, ether_type_2;
164 u8 remainder, padlen = 0;
165
166 if (!skb_cloned(skb)) {
167 int headroom = skb_headroom(skb);
168 int tailroom = skb_tailroom(skb);
169
170 if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom
171 >= KALMIA_HEADER_LENGTH))
172 goto done;
173
174 if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH
175 + KALMIA_ALIGN_SIZE)) {
176 skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH,
177 skb->data, skb->len);
178 skb_set_tail_pointer(skb, skb->len);
179 goto done;
180 }
181 }
182
183 skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH,
184 KALMIA_ALIGN_SIZE, flags);
185 if (!skb2)
186 return NULL;
187
188 dev_kfree_skb_any(skb);
189 skb = skb2;
190
191 done:
192 header_start = skb_push(skb, KALMIA_HEADER_LENGTH);
193 ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12];
194 ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13];
195
196 netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1,
197 ether_type_2);
198
199 /* According to empiric data for data packages */
200 header_start[0] = 0x57;
201 header_start[1] = 0x44;
202 content_len = skb->len - KALMIA_HEADER_LENGTH;
203
204 put_unaligned_le16(content_len, &header_start[2]);
205 header_start[4] = ether_type_1;
206 header_start[5] = ether_type_2;
207
208 /* Align to 4 bytes by padding with zeros */
209 remainder = skb->len % KALMIA_ALIGN_SIZE;
210 if (remainder > 0) {
211 padlen = KALMIA_ALIGN_SIZE - remainder;
212 skb_put_zero(skb, padlen);
213 }
214
215 netdev_dbg(dev->net,
216 "Sending package with length %i and padding %i. Header: %6phC.",
217 content_len, padlen, header_start);
218
219 return skb;
220 }
221
222 static int
kalmia_rx_fixup(struct usbnet * dev,struct sk_buff * skb)223 kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
224 {
225 /*
226 * Our task here is to strip off framing, leaving skb with one
227 * data frame for the usbnet framework code to process.
228 */
229 static const u8 HEADER_END_OF_USB_PACKET[] =
230 { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 };
231 static const u8 EXPECTED_UNKNOWN_HEADER_1[] =
232 { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 };
233 static const u8 EXPECTED_UNKNOWN_HEADER_2[] =
234 { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 };
235 int i = 0;
236
237 /* incomplete header? */
238 if (skb->len < KALMIA_HEADER_LENGTH)
239 return 0;
240
241 do {
242 struct sk_buff *skb2 = NULL;
243 u8 *header_start;
244 u16 usb_packet_length, ether_packet_length;
245 int is_last;
246
247 header_start = skb->data;
248
249 if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) {
250 if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1,
251 sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp(
252 header_start, EXPECTED_UNKNOWN_HEADER_2,
253 sizeof(EXPECTED_UNKNOWN_HEADER_2))) {
254 netdev_dbg(dev->net,
255 "Received expected unknown frame header: %6phC. Package length: %i\n",
256 header_start,
257 skb->len - KALMIA_HEADER_LENGTH);
258 }
259 else {
260 netdev_err(dev->net,
261 "Received unknown frame header: %6phC. Package length: %i\n",
262 header_start,
263 skb->len - KALMIA_HEADER_LENGTH);
264 return 0;
265 }
266 }
267 else
268 netdev_dbg(dev->net,
269 "Received header: %6phC. Package length: %i\n",
270 header_start, skb->len - KALMIA_HEADER_LENGTH);
271
272 /* subtract start header and end header */
273 usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH);
274 ether_packet_length = get_unaligned_le16(&header_start[2]);
275 skb_pull(skb, KALMIA_HEADER_LENGTH);
276
277 /* Some small packets misses end marker */
278 if (usb_packet_length < ether_packet_length) {
279 ether_packet_length = usb_packet_length
280 + KALMIA_HEADER_LENGTH;
281 is_last = true;
282 }
283 else {
284 netdev_dbg(dev->net, "Correct package length #%i", i
285 + 1);
286
287 is_last = (memcmp(skb->data + ether_packet_length,
288 HEADER_END_OF_USB_PACKET,
289 sizeof(HEADER_END_OF_USB_PACKET)) == 0);
290 if (!is_last) {
291 header_start = skb->data + ether_packet_length;
292 netdev_dbg(dev->net,
293 "End header: %6phC. Package length: %i\n",
294 header_start,
295 skb->len - KALMIA_HEADER_LENGTH);
296 }
297 }
298
299 if (is_last) {
300 skb2 = skb;
301 }
302 else {
303 skb2 = skb_clone(skb, GFP_ATOMIC);
304 if (unlikely(!skb2))
305 return 0;
306 }
307
308 skb_trim(skb2, ether_packet_length);
309
310 if (is_last) {
311 return 1;
312 }
313 else {
314 usbnet_skb_return(dev, skb2);
315 skb_pull(skb, ether_packet_length);
316 }
317
318 i++;
319 }
320 while (skb->len);
321
322 return 1;
323 }
324
325 static const struct driver_info kalmia_info = {
326 .description = "Samsung Kalmia LTE USB dongle",
327 .flags = FLAG_WWAN,
328 .bind = kalmia_bind,
329 .rx_fixup = kalmia_rx_fixup,
330 .tx_fixup = kalmia_tx_fixup
331 };
332
333 /*-------------------------------------------------------------------------*/
334
335 static const struct usb_device_id products[] = {
336 /* The unswitched USB ID, to get the module auto loaded: */
337 { USB_DEVICE(0x04e8, 0x689a) },
338 /* The stick switched into modem (by e.g. usb_modeswitch): */
339 { USB_DEVICE(0x04e8, 0x6889),
340 .driver_info = (unsigned long) &kalmia_info, },
341 { /* EMPTY == end of list */} };
342 MODULE_DEVICE_TABLE( usb, products);
343
344 static struct usb_driver kalmia_driver = {
345 .name = "kalmia",
346 .id_table = products,
347 .probe = usbnet_probe,
348 .disconnect = usbnet_disconnect,
349 .suspend = usbnet_suspend,
350 .resume = usbnet_resume,
351 .disable_hub_initiated_lpm = 1,
352 };
353
354 module_usb_driver(kalmia_driver);
355
356 MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>");
357 MODULE_DESCRIPTION("Samsung Kalmia USB network driver");
358 MODULE_LICENSE("GPL");
359
