xref: /openbmc/linux/drivers/net/usb/kalmia.c (revision c68f345b)
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\n",
69 			status);
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\n",
87 			status);
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 	eth_hw_addr_set(dev->net, ethernet_addr);
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