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, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #include <linux/module.h>
22 #include <linux/init.h>
23 #include <linux/netdevice.h>
24 #include <linux/etherdevice.h>
25 #include <linux/ctype.h>
26 #include <linux/ethtool.h>
27 #include <linux/workqueue.h>
28 #include <linux/mii.h>
29 #include <linux/usb.h>
30 #include <linux/crc32.h>
31 #include <linux/usb/cdc.h>
32 #include <linux/usb/usbnet.h>
33 #include <linux/gfp.h>
34
35
36 /*
37 * This driver is an implementation of the CDC "Ethernet Emulation
38 * Model" (EEM) specification, which encapsulates Ethernet frames
39 * for transport over USB using a simpler USB device model than the
40 * previous CDC "Ethernet Control Model" (ECM, or "CDC Ethernet").
41 *
42 * For details, see www.usb.org/developers/devclass_docs/CDC_EEM10.pdf
43 *
44 * This version has been tested with GIGAntIC WuaoW SIM Smart Card on 2.6.24,
45 * 2.6.27 and 2.6.30rc2 kernel.
46 * It has also been validated on Openmoko Om 2008.12 (based on 2.6.24 kernel).
47 * build on 23-April-2009
48 */
49
50 #define EEM_HEAD 2 /* 2 byte header */
51
52 /*-------------------------------------------------------------------------*/
53
eem_linkcmd_complete(struct urb * urb)54 static void eem_linkcmd_complete(struct urb *urb)
55 {
56 dev_kfree_skb(urb->context);
57 usb_free_urb(urb);
58 }
59
eem_linkcmd(struct usbnet * dev,struct sk_buff * skb)60 static void eem_linkcmd(struct usbnet *dev, struct sk_buff *skb)
61 {
62 struct urb *urb;
63 int status;
64
65 urb = usb_alloc_urb(0, GFP_ATOMIC);
66 if (!urb)
67 goto fail;
68
69 usb_fill_bulk_urb(urb, dev->udev, dev->out,
70 skb->data, skb->len, eem_linkcmd_complete, skb);
71
72 status = usb_submit_urb(urb, GFP_ATOMIC);
73 if (status) {
74 usb_free_urb(urb);
75 fail:
76 dev_kfree_skb(skb);
77 netdev_warn(dev->net, "link cmd failure\n");
78 return;
79 }
80 }
81
eem_bind(struct usbnet * dev,struct usb_interface * intf)82 static int eem_bind(struct usbnet *dev, struct usb_interface *intf)
83 {
84 int status = 0;
85
86 status = usbnet_get_endpoints(dev, intf);
87 if (status < 0) {
88 usb_set_intfdata(intf, NULL);
89 usb_driver_release_interface(driver_of(intf), intf);
90 return status;
91 }
92
93 /* no jumbogram (16K) support for now */
94
95 dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN;
96 dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
97
98 return 0;
99 }
100
101 /*
102 * EEM permits packing multiple Ethernet frames into USB transfers
103 * (a "bundle"), but for TX we don't try to do that.
104 */
eem_tx_fixup(struct usbnet * dev,struct sk_buff * skb,gfp_t flags)105 static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
106 gfp_t flags)
107 {
108 struct sk_buff *skb2 = NULL;
109 u16 len = skb->len;
110 u32 crc = 0;
111 int padlen = 0;
112
113 /* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
114 * zero, stick two bytes of zero length EEM packet on the end.
115 * Else the framework would add invalid single byte padding,
116 * since it can't know whether ZLPs will be handled right by
117 * all the relevant hardware and software.
118 */
119 if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
120 padlen += 2;
121
122 if (!skb_cloned(skb)) {
123 int headroom = skb_headroom(skb);
124 int tailroom = skb_tailroom(skb);
125
126 if ((tailroom >= ETH_FCS_LEN + padlen) &&
127 (headroom >= EEM_HEAD))
128 goto done;
129
130 if ((headroom + tailroom)
131 > (EEM_HEAD + ETH_FCS_LEN + padlen)) {
132 skb->data = memmove(skb->head +
133 EEM_HEAD,
134 skb->data,
135 skb->len);
136 skb_set_tail_pointer(skb, len);
137 goto done;
138 }
139 }
140
141 skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
142 if (!skb2)
143 return NULL;
144
145 dev_kfree_skb_any(skb);
146 skb = skb2;
147
148 done:
149 /* we don't use the "no Ethernet CRC" option */
150 crc = crc32_le(~0, skb->data, skb->len);
151 crc = ~crc;
152
153 put_unaligned_le32(crc, skb_put(skb, 4));
154
155 /* EEM packet header format:
156 * b0..13: length of ethernet frame
157 * b14: bmCRC (1 == valid Ethernet CRC)
158 * b15: bmType (0 == data)
159 */
160 len = skb->len;
161 put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));
162
163 /* Bundle a zero length EEM packet if needed */
164 if (padlen)
165 put_unaligned_le16(0, skb_put(skb, 2));
166
167 return skb;
168 }
169
eem_rx_fixup(struct usbnet * dev,struct sk_buff * skb)170 static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
171 {
172 /*
173 * Our task here is to strip off framing, leaving skb with one
174 * data frame for the usbnet framework code to process. But we
175 * may have received multiple EEM payloads, or command payloads.
176 * So we must process _everything_ as if it's a header, except
177 * maybe the last data payload
178 *
179 * REVISIT the framework needs updating so that when we consume
180 * all payloads (the last or only message was a command, or a
181 * zero length EEM packet) that is not accounted as an rx_error.
182 */
183 do {
184 struct sk_buff *skb2 = NULL;
185 u16 header;
186 u16 len = 0;
187
188 /* incomplete EEM header? */
189 if (skb->len < EEM_HEAD)
190 return 0;
191
192 /*
193 * EEM packet header format:
194 * b0..14: EEM type dependent (Data or Command)
195 * b15: bmType
196 */
197 header = get_unaligned_le16(skb->data);
198 skb_pull(skb, EEM_HEAD);
199
200 /*
201 * The bmType bit helps to denote when EEM
202 * packet is data or command :
203 * bmType = 0 : EEM data payload
204 * bmType = 1 : EEM (link) command
205 */
206 if (header & BIT(15)) {
207 u16 bmEEMCmd;
208
209 /*
210 * EEM (link) command packet:
211 * b0..10: bmEEMCmdParam
212 * b11..13: bmEEMCmd
213 * b14: bmReserved (must be 0)
214 * b15: 1 (EEM command)
215 */
216 if (header & BIT(14)) {
217 netdev_dbg(dev->net, "reserved command %04x\n",
218 header);
219 continue;
220 }
221
222 bmEEMCmd = (header >> 11) & 0x7;
223 switch (bmEEMCmd) {
224
225 /* Responding to echo requests is mandatory. */
226 case 0: /* Echo command */
227 len = header & 0x7FF;
228
229 /* bogus command? */
230 if (skb->len < len)
231 return 0;
232
233 skb2 = skb_clone(skb, GFP_ATOMIC);
234 if (unlikely(!skb2))
235 goto next;
236 skb_trim(skb2, len);
237 put_unaligned_le16(BIT(15) | (1 << 11) | len,
238 skb_push(skb2, 2));
239 eem_linkcmd(dev, skb2);
240 break;
241
242 /*
243 * Host may choose to ignore hints.
244 * - suspend: peripheral ready to suspend
245 * - response: suggest N millisec polling
246 * - response complete: suggest N sec polling
247 */
248 case 2: /* Suspend hint */
249 case 3: /* Response hint */
250 case 4: /* Response complete hint */
251 continue;
252
253 /*
254 * Hosts should never receive host-to-peripheral
255 * or reserved command codes; or responses to an
256 * echo command we didn't send.
257 */
258 case 1: /* Echo response */
259 case 5: /* Tickle */
260 default: /* reserved */
261 netdev_warn(dev->net,
262 "unexpected link command %d\n",
263 bmEEMCmd);
264 continue;
265 }
266
267 } else {
268 u32 crc, crc2;
269 int is_last;
270
271 /* zero length EEM packet? */
272 if (header == 0)
273 continue;
274
275 /*
276 * EEM data packet header :
277 * b0..13: length of ethernet frame
278 * b14: bmCRC
279 * b15: 0 (EEM data)
280 */
281 len = header & 0x3FFF;
282
283 /* bogus EEM payload? */
284 if (skb->len < len)
285 return 0;
286
287 /* bogus ethernet frame? */
288 if (len < (ETH_HLEN + ETH_FCS_LEN))
289 goto next;
290
291 /*
292 * Treat the last payload differently: framework
293 * code expects our "fixup" to have stripped off
294 * headers, so "skb" is a data packet (or error).
295 * Else if it's not the last payload, keep "skb"
296 * for further processing.
297 */
298 is_last = (len == skb->len);
299 if (is_last)
300 skb2 = skb;
301 else {
302 skb2 = skb_clone(skb, GFP_ATOMIC);
303 if (unlikely(!skb2))
304 return 0;
305 }
306
307 /*
308 * The bmCRC helps to denote when the CRC field in
309 * the Ethernet frame contains a calculated CRC:
310 * bmCRC = 1 : CRC is calculated
311 * bmCRC = 0 : CRC = 0xDEADBEEF
312 */
313 if (header & BIT(14)) {
314 crc = get_unaligned_le32(skb2->data
315 + len - ETH_FCS_LEN);
316 crc2 = ~crc32_le(~0, skb2->data, skb2->len
317 - ETH_FCS_LEN);
318 } else {
319 crc = get_unaligned_be32(skb2->data
320 + len - ETH_FCS_LEN);
321 crc2 = 0xdeadbeef;
322 }
323 skb_trim(skb2, len - ETH_FCS_LEN);
324
325 if (is_last)
326 return crc == crc2;
327
328 if (unlikely(crc != crc2)) {
329 dev->net->stats.rx_errors++;
330 dev_kfree_skb_any(skb2);
331 } else
332 usbnet_skb_return(dev, skb2);
333 }
334
335 next:
336 skb_pull(skb, len);
337 } while (skb->len);
338
339 return 1;
340 }
341
342 static const struct driver_info eem_info = {
343 .description = "CDC EEM Device",
344 .flags = FLAG_ETHER | FLAG_POINTTOPOINT,
345 .bind = eem_bind,
346 .rx_fixup = eem_rx_fixup,
347 .tx_fixup = eem_tx_fixup,
348 };
349
350 /*-------------------------------------------------------------------------*/
351
352 static const struct usb_device_id products[] = {
353 {
354 USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
355 USB_CDC_PROTO_EEM),
356 .driver_info = (unsigned long) &eem_info,
357 },
358 {
359 /* EMPTY == end of list */
360 },
361 };
362 MODULE_DEVICE_TABLE(usb, products);
363
364 static struct usb_driver eem_driver = {
365 .name = "cdc_eem",
366 .id_table = products,
367 .probe = usbnet_probe,
368 .disconnect = usbnet_disconnect,
369 .suspend = usbnet_suspend,
370 .resume = usbnet_resume,
371 };
372
373 module_usb_driver(eem_driver);
374
375 MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
376 MODULE_DESCRIPTION("USB CDC EEM");
377 MODULE_LICENSE("GPL");
378