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Linux/drivers/net/usb/kalmia.c

  1 /*
  2  * USB network interface driver for Samsung Kalmia based LTE USB modem like the
  3  * Samsung GT-B3730 and GT-B3710.
  4  *
  5  * Copyright (C) 2011 Marius Bjoernstad Kotsbak <marius@kotsbak.com>
  6  *
  7  * Sponsored by Quicklink Video Distribution Services Ltd.
  8  *
  9  * Based on the cdc_eem module.
 10  *
 11  * This program is free software; you can redistribute it and/or modify
 12  * it under the terms of the GNU General Public License as published by
 13  * the Free Software Foundation; either version 2 of the License, or
 14  * (at your option) any later version.
 15  */
 16 
 17 #include <linux/module.h>
 18 #include <linux/netdevice.h>
 19 #include <linux/etherdevice.h>
 20 #include <linux/ctype.h>
 21 #include <linux/ethtool.h>
 22 #include <linux/workqueue.h>
 23 #include <linux/mii.h>
 24 #include <linux/usb.h>
 25 #include <linux/crc32.h>
 26 #include <linux/usb/cdc.h>
 27 #include <linux/usb/usbnet.h>
 28 #include <linux/gfp.h>
 29 
 30 /*
 31  * The Samsung Kalmia based LTE USB modems have a CDC ACM port for modem control
 32  * handled by the "option" module and an ethernet data port handled by this
 33  * module.
 34  *
 35  * The stick must first be switched into modem mode by usb_modeswitch
 36  * or similar tool. Then the modem gets sent two initialization packets by
 37  * this module, which gives the MAC address of the device. User space can then
 38  * connect the modem using AT commands through the ACM port and then use
 39  * DHCP on the network interface exposed by this module. Network packets are
 40  * sent to and from the modem in a proprietary format discovered after watching
 41  * the behavior of the windows driver for the modem.
 42  *
 43  * More information about the use of the modem is available in usb_modeswitch
 44  * forum and the project page:
 45  *
 46  * http://www.draisberghof.de/usb_modeswitch/bb/viewtopic.php?t=465
 47  * https://github.com/mkotsbak/Samsung-GT-B3730-linux-driver
 48  */
 49 
 50 /* #define      DEBUG */
 51 /* #define      VERBOSE */
 52 
 53 #define KALMIA_HEADER_LENGTH 6
 54 #define KALMIA_ALIGN_SIZE 4
 55 #define KALMIA_USB_TIMEOUT 10000
 56 
 57 /*-------------------------------------------------------------------------*/
 58 
 59 static int
 60 kalmia_send_init_packet(struct usbnet *dev, u8 *init_msg, u8 init_msg_len,
 61         u8 *buffer, u8 expected_len)
 62 {
 63         int act_len;
 64         int status;
 65 
 66         netdev_dbg(dev->net, "Sending init packet");
 67 
 68         status = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 0x02),
 69                 init_msg, init_msg_len, &act_len, KALMIA_USB_TIMEOUT);
 70         if (status != 0) {
 71                 netdev_err(dev->net,
 72                         "Error sending init packet. Status %i, length %i\n",
 73                         status, act_len);
 74                 return status;
 75         }
 76         else if (act_len != init_msg_len) {
 77                 netdev_err(dev->net,
 78                         "Did not send all of init packet. Bytes sent: %i",
 79                         act_len);
 80         }
 81         else {
 82                 netdev_dbg(dev->net, "Successfully sent init packet.");
 83         }
 84 
 85         status = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, 0x81),
 86                 buffer, expected_len, &act_len, KALMIA_USB_TIMEOUT);
 87 
 88         if (status != 0)
 89                 netdev_err(dev->net,
 90                         "Error receiving init result. Status %i, length %i\n",
 91                         status, act_len);
 92         else if (act_len != expected_len)
 93                 netdev_err(dev->net, "Unexpected init result length: %i\n",
 94                         act_len);
 95 
 96         return status;
 97 }
 98 
 99 static int
100 kalmia_init_and_get_ethernet_addr(struct usbnet *dev, u8 *ethernet_addr)
101 {
102         static const char init_msg_1[] =
103                 { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
104                 0x00, 0x00 };
105         static const char init_msg_2[] =
106                 { 0x57, 0x50, 0x04, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xf4,
107                 0x00, 0x00 };
108         static const int buflen = 28;
109         char *usb_buf;
110         int status;
111 
112         usb_buf = kmalloc(buflen, GFP_DMA | GFP_KERNEL);
113         if (!usb_buf)
114                 return -ENOMEM;
115 
116         memcpy(usb_buf, init_msg_1, 12);
117         status = kalmia_send_init_packet(dev, usb_buf, sizeof(init_msg_1)
118                 / sizeof(init_msg_1[0]), usb_buf, 24);
119         if (status != 0)
120                 return status;
121 
122         memcpy(usb_buf, init_msg_2, 12);
123         status = kalmia_send_init_packet(dev, usb_buf, sizeof(init_msg_2)
124                 / sizeof(init_msg_2[0]), usb_buf, 28);
125         if (status != 0)
126                 return status;
127 
128         memcpy(ethernet_addr, usb_buf + 10, ETH_ALEN);
129 
130         kfree(usb_buf);
131         return status;
132 }
133 
134 static int
135 kalmia_bind(struct usbnet *dev, struct usb_interface *intf)
136 {
137         int status;
138         u8 ethernet_addr[ETH_ALEN];
139 
140         /* Don't bind to AT command interface */
141         if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
142                 return -EINVAL;
143 
144         dev->in = usb_rcvbulkpipe(dev->udev, 0x81 & USB_ENDPOINT_NUMBER_MASK);
145         dev->out = usb_sndbulkpipe(dev->udev, 0x02 & USB_ENDPOINT_NUMBER_MASK);
146         dev->status = NULL;
147 
148         dev->net->hard_header_len += KALMIA_HEADER_LENGTH;
149         dev->hard_mtu = 1400;
150         dev->rx_urb_size = dev->hard_mtu * 10; // Found as optimal after testing
151 
152         status = kalmia_init_and_get_ethernet_addr(dev, ethernet_addr);
153 
154         if (status < 0) {
155                 usb_set_intfdata(intf, NULL);
156                 usb_driver_release_interface(driver_of(intf), intf);
157                 return status;
158         }
159 
160         memcpy(dev->net->dev_addr, ethernet_addr, ETH_ALEN);
161 
162         return status;
163 }
164 
165 static struct sk_buff *
166 kalmia_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
167 {
168         struct sk_buff *skb2 = NULL;
169         u16 content_len;
170         unsigned char *header_start;
171         unsigned char ether_type_1, ether_type_2;
172         u8 remainder, padlen = 0;
173 
174         if (!skb_cloned(skb)) {
175                 int headroom = skb_headroom(skb);
176                 int tailroom = skb_tailroom(skb);
177 
178                 if ((tailroom >= KALMIA_ALIGN_SIZE) && (headroom
179                         >= KALMIA_HEADER_LENGTH))
180                         goto done;
181 
182                 if ((headroom + tailroom) > (KALMIA_HEADER_LENGTH
183                         + KALMIA_ALIGN_SIZE)) {
184                         skb->data = memmove(skb->head + KALMIA_HEADER_LENGTH,
185                                 skb->data, skb->len);
186                         skb_set_tail_pointer(skb, skb->len);
187                         goto done;
188                 }
189         }
190 
191         skb2 = skb_copy_expand(skb, KALMIA_HEADER_LENGTH,
192                 KALMIA_ALIGN_SIZE, flags);
193         if (!skb2)
194                 return NULL;
195 
196         dev_kfree_skb_any(skb);
197         skb = skb2;
198 
199 done:
200         header_start = skb_push(skb, KALMIA_HEADER_LENGTH);
201         ether_type_1 = header_start[KALMIA_HEADER_LENGTH + 12];
202         ether_type_2 = header_start[KALMIA_HEADER_LENGTH + 13];
203 
204         netdev_dbg(dev->net, "Sending etherType: %02x%02x", ether_type_1,
205                 ether_type_2);
206 
207         /* According to empiric data for data packages */
208         header_start[0] = 0x57;
209         header_start[1] = 0x44;
210         content_len = skb->len - KALMIA_HEADER_LENGTH;
211 
212         put_unaligned_le16(content_len, &header_start[2]);
213         header_start[4] = ether_type_1;
214         header_start[5] = ether_type_2;
215 
216         /* Align to 4 bytes by padding with zeros */
217         remainder = skb->len % KALMIA_ALIGN_SIZE;
218         if (remainder > 0) {
219                 padlen = KALMIA_ALIGN_SIZE - remainder;
220                 memset(skb_put(skb, padlen), 0, padlen);
221         }
222 
223         netdev_dbg(dev->net,
224                 "Sending package with length %i and padding %i. Header: %6phC.",
225                 content_len, padlen, header_start);
226 
227         return skb;
228 }
229 
230 static int
231 kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
232 {
233         /*
234          * Our task here is to strip off framing, leaving skb with one
235          * data frame for the usbnet framework code to process.
236          */
237         static const u8 HEADER_END_OF_USB_PACKET[] =
238                 { 0x57, 0x5a, 0x00, 0x00, 0x08, 0x00 };
239         static const u8 EXPECTED_UNKNOWN_HEADER_1[] =
240                 { 0x57, 0x43, 0x1e, 0x00, 0x15, 0x02 };
241         static const u8 EXPECTED_UNKNOWN_HEADER_2[] =
242                 { 0x57, 0x50, 0x0e, 0x00, 0x00, 0x00 };
243         int i = 0;
244 
245         /* incomplete header? */
246         if (skb->len < KALMIA_HEADER_LENGTH)
247                 return 0;
248 
249         do {
250                 struct sk_buff *skb2 = NULL;
251                 u8 *header_start;
252                 u16 usb_packet_length, ether_packet_length;
253                 int is_last;
254 
255                 header_start = skb->data;
256 
257                 if (unlikely(header_start[0] != 0x57 || header_start[1] != 0x44)) {
258                         if (!memcmp(header_start, EXPECTED_UNKNOWN_HEADER_1,
259                                 sizeof(EXPECTED_UNKNOWN_HEADER_1)) || !memcmp(
260                                 header_start, EXPECTED_UNKNOWN_HEADER_2,
261                                 sizeof(EXPECTED_UNKNOWN_HEADER_2))) {
262                                 netdev_dbg(dev->net,
263                                         "Received expected unknown frame header: %6phC. Package length: %i\n",
264                                         header_start,
265                                         skb->len - KALMIA_HEADER_LENGTH);
266                         }
267                         else {
268                                 netdev_err(dev->net,
269                                         "Received unknown frame header: %6phC. Package length: %i\n",
270                                         header_start,
271                                         skb->len - KALMIA_HEADER_LENGTH);
272                                 return 0;
273                         }
274                 }
275                 else
276                         netdev_dbg(dev->net,
277                                 "Received header: %6phC. Package length: %i\n",
278                                 header_start, skb->len - KALMIA_HEADER_LENGTH);
279 
280                 /* subtract start header and end header */
281                 usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH);
282                 ether_packet_length = get_unaligned_le16(&header_start[2]);
283                 skb_pull(skb, KALMIA_HEADER_LENGTH);
284 
285                 /* Some small packets misses end marker */
286                 if (usb_packet_length < ether_packet_length) {
287                         ether_packet_length = usb_packet_length
288                                 + KALMIA_HEADER_LENGTH;
289                         is_last = true;
290                 }
291                 else {
292                         netdev_dbg(dev->net, "Correct package length #%i", i
293                                 + 1);
294 
295                         is_last = (memcmp(skb->data + ether_packet_length,
296                                 HEADER_END_OF_USB_PACKET,
297                                 sizeof(HEADER_END_OF_USB_PACKET)) == 0);
298                         if (!is_last) {
299                                 header_start = skb->data + ether_packet_length;
300                                 netdev_dbg(dev->net,
301                                         "End header: %6phC. Package length: %i\n",
302                                         header_start,
303                                         skb->len - KALMIA_HEADER_LENGTH);
304                         }
305                 }
306 
307                 if (is_last) {
308                         skb2 = skb;
309                 }
310                 else {
311                         skb2 = skb_clone(skb, GFP_ATOMIC);
312                         if (unlikely(!skb2))
313                                 return 0;
314                 }
315 
316                 skb_trim(skb2, ether_packet_length);
317 
318                 if (is_last) {
319                         return 1;
320                 }
321                 else {
322                         usbnet_skb_return(dev, skb2);
323                         skb_pull(skb, ether_packet_length);
324                 }
325 
326                 i++;
327         }
328         while (skb->len);
329 
330         return 1;
331 }
332 
333 static const struct driver_info kalmia_info = {
334         .description = "Samsung Kalmia LTE USB dongle",
335         .flags = FLAG_WWAN,
336         .bind = kalmia_bind,
337         .rx_fixup = kalmia_rx_fixup,
338         .tx_fixup = kalmia_tx_fixup
339 };
340 
341 /*-------------------------------------------------------------------------*/
342 
343 static const struct usb_device_id products[] = {
344         /* The unswitched USB ID, to get the module auto loaded: */
345         { USB_DEVICE(0x04e8, 0x689a) },
346         /* The stick swithed into modem (by e.g. usb_modeswitch): */
347         { USB_DEVICE(0x04e8, 0x6889),
348                 .driver_info = (unsigned long) &kalmia_info, },
349         { /* EMPTY == end of list */} };
350 MODULE_DEVICE_TABLE( usb, products);
351 
352 static struct usb_driver kalmia_driver = {
353         .name = "kalmia",
354         .id_table = products,
355         .probe = usbnet_probe,
356         .disconnect = usbnet_disconnect,
357         .suspend = usbnet_suspend,
358         .resume = usbnet_resume,
359         .disable_hub_initiated_lpm = 1,
360 };
361 
362 module_usb_driver(kalmia_driver);
363 
364 MODULE_AUTHOR("Marius Bjoernstad Kotsbak <marius@kotsbak.com>");
365 MODULE_DESCRIPTION("Samsung Kalmia USB network driver");
366 MODULE_LICENSE("GPL");
367 

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