1 /*
2 * USB CDC EEM network interface driver
3 * Copyright (C) 2009 Oberthur Technologies
4 * by Omar Laazimani, Olivier Condemine
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include <linux/module.h>
21 #include <linux/netdevice.h>
22 #include <linux/etherdevice.h>
23 #include <linux/ctype.h>
24 #include <linux/ethtool.h>
25 #include <linux/workqueue.h>
26 #include <linux/mii.h>
27 #include <linux/usb.h>
28 #include <linux/crc32.h>
29 #include <linux/usb/cdc.h>
30 #include <linux/usb/usbnet.h>
31 #include <linux/gfp.h>
32 #include <linux/if_vlan.h>
33
34
35 /*
36 * This driver is an implementation of the CDC "Ethernet Emulation
37 * Model" (EEM) specification, which encapsulates Ethernet frames
38 * for transport over USB using a simpler USB device model than the
39 * previous CDC "Ethernet Control Model" (ECM, or "CDC Ethernet").
40 *
41 * For details, see www.usb.org/developers/devclass_docs/CDC_EEM10.pdf
42 *
43 * This version has been tested with GIGAntIC WuaoW SIM Smart Card on 2.6.24,
44 * 2.6.27 and 2.6.30rc2 kernel.
45 * It has also been validated on Openmoko Om 2008.12 (based on 2.6.24 kernel).
46 * build on 23-April-2009
47 */
48
49 #define EEM_HEAD 2 /* 2 byte header */
50
51 /*-------------------------------------------------------------------------*/
52
eem_linkcmd_complete(struct urb * urb)53 static void eem_linkcmd_complete(struct urb *urb)
54 {
55 dev_kfree_skb(urb->context);
56 usb_free_urb(urb);
57 }
58
eem_linkcmd(struct usbnet * dev,struct sk_buff * skb)59 static void eem_linkcmd(struct usbnet *dev, struct sk_buff *skb)
60 {
61 struct urb *urb;
62 int status;
63
64 urb = usb_alloc_urb(0, GFP_ATOMIC);
65 if (!urb)
66 goto fail;
67
68 usb_fill_bulk_urb(urb, dev->udev, dev->out,
69 skb->data, skb->len, eem_linkcmd_complete, skb);
70
71 status = usb_submit_urb(urb, GFP_ATOMIC);
72 if (status) {
73 usb_free_urb(urb);
74 fail:
75 dev_kfree_skb(skb);
76 netdev_warn(dev->net, "link cmd failure\n");
77 return;
78 }
79 }
80
eem_bind(struct usbnet * dev,struct usb_interface * intf)81 static int eem_bind(struct usbnet *dev, struct usb_interface *intf)
82 {
83 int status = 0;
84
85 status = usbnet_get_endpoints(dev, intf);
86 if (status < 0) {
87 usb_set_intfdata(intf, NULL);
88 usb_driver_release_interface(driver_of(intf), intf);
89 return status;
90 }
91
92 /* no jumbogram (16K) support for now */
93
94 dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN + VLAN_HLEN;
95 dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
96
97 return 0;
98 }
99
100 /*
101 * EEM permits packing multiple Ethernet frames into USB transfers
102 * (a "bundle"), but for TX we don't try to do that.
103 */
eem_tx_fixup(struct usbnet * dev,struct sk_buff * skb,gfp_t flags)104 static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
105 gfp_t flags)
106 {
107 struct sk_buff *skb2 = NULL;
108 u16 len = skb->len;
109 u32 crc = 0;
110 int padlen = 0;
111
112 /* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
113 * zero, stick two bytes of zero length EEM packet on the end.
114 * Else the framework would add invalid single byte padding,
115 * since it can't know whether ZLPs will be handled right by
116 * all the relevant hardware and software.
117 */
118 if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
119 padlen += 2;
120
121 if (!skb_cloned(skb)) {
122 int headroom = skb_headroom(skb);
123 int tailroom = skb_tailroom(skb);
124
125 if ((tailroom >= ETH_FCS_LEN + padlen) &&
126 (headroom >= EEM_HEAD))
127 goto done;
128
129 if ((headroom + tailroom)
130 > (EEM_HEAD + ETH_FCS_LEN + padlen)) {
131 skb->data = memmove(skb->head +
132 EEM_HEAD,
133 skb->data,
134 skb->len);
135 skb_set_tail_pointer(skb, len);
136 goto done;
137 }
138 }
139
140 skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
141 if (!skb2)
142 return NULL;
143
144 dev_kfree_skb_any(skb);
145 skb = skb2;
146
147 done:
148 /* we don't use the "no Ethernet CRC" option */
149 crc = crc32_le(~0, skb->data, skb->len);
150 crc = ~crc;
151
152 put_unaligned_le32(crc, skb_put(skb, 4));
153
154 /* EEM packet header format:
155 * b0..13: length of ethernet frame
156 * b14: bmCRC (1 == valid Ethernet CRC)
157 * b15: bmType (0 == data)
158 */
159 len = skb->len;
160 put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));
161
162 /* Bundle a zero length EEM packet if needed */
163 if (padlen)
164 put_unaligned_le16(0, skb_put(skb, 2));
165
166 return skb;
167 }
168
eem_rx_fixup(struct usbnet * dev,struct sk_buff * skb)169 static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
170 {
171 /*
172 * Our task here is to strip off framing, leaving skb with one
173 * data frame for the usbnet framework code to process. But we
174 * may have received multiple EEM payloads, or command payloads.
175 * So we must process _everything_ as if it's a header, except
176 * maybe the last data payload
177 *
178 * REVISIT the framework needs updating so that when we consume
179 * all payloads (the last or only message was a command, or a
180 * zero length EEM packet) that is not accounted as an rx_error.
181 */
182 do {
183 struct sk_buff *skb2 = NULL;
184 u16 header;
185 u16 len = 0;
186
187 /* incomplete EEM header? */
188 if (skb->len < EEM_HEAD)
189 return 0;
190
191 /*
192 * EEM packet header format:
193 * b0..14: EEM type dependent (Data or Command)
194 * b15: bmType
195 */
196 header = get_unaligned_le16(skb->data);
197 skb_pull(skb, EEM_HEAD);
198
199 /*
200 * The bmType bit helps to denote when EEM
201 * packet is data or command :
202 * bmType = 0 : EEM data payload
203 * bmType = 1 : EEM (link) command
204 */
205 if (header & BIT(15)) {
206 u16 bmEEMCmd;
207
208 /*
209 * EEM (link) command packet:
210 * b0..10: bmEEMCmdParam
211 * b11..13: bmEEMCmd
212 * b14: bmReserved (must be 0)
213 * b15: 1 (EEM command)
214 */
215 if (header & BIT(14)) {
216 netdev_dbg(dev->net, "reserved command %04x\n",
217 header);
218 continue;
219 }
220
221 bmEEMCmd = (header >> 11) & 0x7;
222 switch (bmEEMCmd) {
223
224 /* Responding to echo requests is mandatory. */
225 case 0: /* Echo command */
226 len = header & 0x7FF;
227
228 /* bogus command? */
229 if (skb->len < len)
230 return 0;
231
232 skb2 = skb_clone(skb, GFP_ATOMIC);
233 if (unlikely(!skb2))
234 goto next;
235 skb_trim(skb2, len);
236 put_unaligned_le16(BIT(15) | (1 << 11) | len,
237 skb_push(skb2, 2));
238 eem_linkcmd(dev, skb2);
239 break;
240
241 /*
242 * Host may choose to ignore hints.
243 * - suspend: peripheral ready to suspend
244 * - response: suggest N millisec polling
245 * - response complete: suggest N sec polling
246 *
247 * Suspend is reported and maybe heeded.
248 */
249 case 2: /* Suspend hint */
250 usbnet_device_suggests_idle(dev);
251 continue;
252 case 3: /* Response hint */
253 case 4: /* Response complete hint */
254 continue;
255
256 /*
257 * Hosts should never receive host-to-peripheral
258 * or reserved command codes; or responses to an
259 * echo command we didn't send.
260 */
261 case 1: /* Echo response */
262 case 5: /* Tickle */
263 default: /* reserved */
264 netdev_warn(dev->net,
265 "unexpected link command %d\n",
266 bmEEMCmd);
267 continue;
268 }
269
270 } else {
271 u32 crc, crc2;
272 int is_last;
273
274 /* zero length EEM packet? */
275 if (header == 0)
276 continue;
277
278 /*
279 * EEM data packet header :
280 * b0..13: length of ethernet frame
281 * b14: bmCRC
282 * b15: 0 (EEM data)
283 */
284 len = header & 0x3FFF;
285
286 /* bogus EEM payload? */
287 if (skb->len < len)
288 return 0;
289
290 /* bogus ethernet frame? */
291 if (len < (ETH_HLEN + ETH_FCS_LEN))
292 goto next;
293
294 /*
295 * Treat the last payload differently: framework
296 * code expects our "fixup" to have stripped off
297 * headers, so "skb" is a data packet (or error).
298 * Else if it's not the last payload, keep "skb"
299 * for further processing.
300 */
301 is_last = (len == skb->len);
302 if (is_last)
303 skb2 = skb;
304 else {
305 skb2 = skb_clone(skb, GFP_ATOMIC);
306 if (unlikely(!skb2))
307 return 0;
308 }
309
310 /*
311 * The bmCRC helps to denote when the CRC field in
312 * the Ethernet frame contains a calculated CRC:
313 * bmCRC = 1 : CRC is calculated
314 * bmCRC = 0 : CRC = 0xDEADBEEF
315 */
316 if (header & BIT(14)) {
317 crc = get_unaligned_le32(skb2->data
318 + len - ETH_FCS_LEN);
319 crc2 = ~crc32_le(~0, skb2->data, skb2->len
320 - ETH_FCS_LEN);
321 } else {
322 crc = get_unaligned_be32(skb2->data
323 + len - ETH_FCS_LEN);
324 crc2 = 0xdeadbeef;
325 }
326 skb_trim(skb2, len - ETH_FCS_LEN);
327
328 if (is_last)
329 return crc == crc2;
330
331 if (unlikely(crc != crc2)) {
332 dev->net->stats.rx_errors++;
333 dev_kfree_skb_any(skb2);
334 } else
335 usbnet_skb_return(dev, skb2);
336 }
337
338 next:
339 skb_pull(skb, len);
340 } while (skb->len);
341
342 return 1;
343 }
344
345 static const struct driver_info eem_info = {
346 .description = "CDC EEM Device",
347 .flags = FLAG_ETHER | FLAG_POINTTOPOINT,
348 .bind = eem_bind,
349 .rx_fixup = eem_rx_fixup,
350 .tx_fixup = eem_tx_fixup,
351 };
352
353 /*-------------------------------------------------------------------------*/
354
355 static const struct usb_device_id products[] = {
356 {
357 USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
358 USB_CDC_PROTO_EEM),
359 .driver_info = (unsigned long) &eem_info,
360 },
361 {
362 /* EMPTY == end of list */
363 },
364 };
365 MODULE_DEVICE_TABLE(usb, products);
366
367 static struct usb_driver eem_driver = {
368 .name = "cdc_eem",
369 .id_table = products,
370 .probe = usbnet_probe,
371 .disconnect = usbnet_disconnect,
372 .suspend = usbnet_suspend,
373 .resume = usbnet_resume,
374 .disable_hub_initiated_lpm = 1,
375 };
376
377 module_usb_driver(eem_driver);
378
379 MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
380 MODULE_DESCRIPTION("USB CDC EEM");
381 MODULE_LICENSE("GPL");
382