2 * USB CDC EEM network interface driver
3 * Copyright (C) 2009 Oberthur Technologies
4 * by Omar Laazimani, Olivier Condemine
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.
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.
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/>.
20 #include <linux/module.h>
21 #include <linux/init.h>
22 #include <linux/netdevice.h>
23 #include <linux/etherdevice.h>
24 #include <linux/ctype.h>
25 #include <linux/ethtool.h>
26 #include <linux/workqueue.h>
27 #include <linux/mii.h>
28 #include <linux/usb.h>
29 #include <linux/crc32.h>
30 #include <linux/usb/cdc.h>
31 #include <linux/usb/usbnet.h>
32 #include <linux/gfp.h>
33 #include <linux/if_vlan.h>
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").
42 * For details, see www.usb.org/developers/devclass_docs/CDC_EEM10.pdf
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
50 #define EEM_HEAD 2 /* 2 byte header */
52 /*-------------------------------------------------------------------------*/
54 static void eem_linkcmd_complete(struct urb
*urb
)
56 dev_kfree_skb(urb
->context
);
60 static void eem_linkcmd(struct usbnet
*dev
, struct sk_buff
*skb
)
65 urb
= usb_alloc_urb(0, GFP_ATOMIC
);
69 usb_fill_bulk_urb(urb
, dev
->udev
, dev
->out
,
70 skb
->data
, skb
->len
, eem_linkcmd_complete
, skb
);
72 status
= usb_submit_urb(urb
, GFP_ATOMIC
);
77 netdev_warn(dev
->net
, "link cmd failure\n");
82 static int eem_bind(struct usbnet
*dev
, struct usb_interface
*intf
)
86 status
= usbnet_get_endpoints(dev
, intf
);
88 usb_set_intfdata(intf
, NULL
);
89 usb_driver_release_interface(driver_of(intf
), intf
);
93 /* no jumbogram (16K) support for now */
95 dev
->net
->hard_header_len
+= EEM_HEAD
+ ETH_FCS_LEN
+ VLAN_HLEN
;
96 dev
->hard_mtu
= dev
->net
->mtu
+ dev
->net
->hard_header_len
;
102 * EEM permits packing multiple Ethernet frames into USB transfers
103 * (a "bundle"), but for TX we don't try to do that.
105 static struct sk_buff
*eem_tx_fixup(struct usbnet
*dev
, struct sk_buff
*skb
,
108 struct sk_buff
*skb2
= NULL
;
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.
119 if (!((len
+ EEM_HEAD
+ ETH_FCS_LEN
) % dev
->maxpacket
))
122 if (!skb_cloned(skb
)) {
123 int headroom
= skb_headroom(skb
);
124 int tailroom
= skb_tailroom(skb
);
126 if ((tailroom
>= ETH_FCS_LEN
+ padlen
) &&
127 (headroom
>= EEM_HEAD
))
130 if ((headroom
+ tailroom
)
131 > (EEM_HEAD
+ ETH_FCS_LEN
+ padlen
)) {
132 skb
->data
= memmove(skb
->head
+
136 skb_set_tail_pointer(skb
, len
);
141 skb2
= skb_copy_expand(skb
, EEM_HEAD
, ETH_FCS_LEN
+ padlen
, flags
);
145 dev_kfree_skb_any(skb
);
149 /* we don't use the "no Ethernet CRC" option */
150 crc
= crc32_le(~0, skb
->data
, skb
->len
);
153 put_unaligned_le32(crc
, skb_put(skb
, 4));
155 /* EEM packet header format:
156 * b0..13: length of ethernet frame
157 * b14: bmCRC (1 == valid Ethernet CRC)
158 * b15: bmType (0 == data)
161 put_unaligned_le16(BIT(14) | len
, skb_push(skb
, 2));
163 /* Bundle a zero length EEM packet if needed */
165 put_unaligned_le16(0, skb_put(skb
, 2));
170 static int eem_rx_fixup(struct usbnet
*dev
, struct sk_buff
*skb
)
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
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.
184 struct sk_buff
*skb2
= NULL
;
188 /* incomplete EEM header? */
189 if (skb
->len
< EEM_HEAD
)
193 * EEM packet header format:
194 * b0..14: EEM type dependent (Data or Command)
197 header
= get_unaligned_le16(skb
->data
);
198 skb_pull(skb
, EEM_HEAD
);
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
206 if (header
& BIT(15)) {
210 * EEM (link) command packet:
211 * b0..10: bmEEMCmdParam
213 * b14: bmReserved (must be 0)
214 * b15: 1 (EEM command)
216 if (header
& BIT(14)) {
217 netdev_dbg(dev
->net
, "reserved command %04x\n",
222 bmEEMCmd
= (header
>> 11) & 0x7;
225 /* Responding to echo requests is mandatory. */
226 case 0: /* Echo command */
227 len
= header
& 0x7FF;
233 skb2
= skb_clone(skb
, GFP_ATOMIC
);
237 put_unaligned_le16(BIT(15) | (1 << 11) | len
,
239 eem_linkcmd(dev
, skb2
);
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
248 * Suspend is reported and maybe heeded.
250 case 2: /* Suspend hint */
251 usbnet_device_suggests_idle(dev
);
253 case 3: /* Response hint */
254 case 4: /* Response complete hint */
258 * Hosts should never receive host-to-peripheral
259 * or reserved command codes; or responses to an
260 * echo command we didn't send.
262 case 1: /* Echo response */
264 default: /* reserved */
265 netdev_warn(dev
->net
,
266 "unexpected link command %d\n",
275 /* zero length EEM packet? */
280 * EEM data packet header :
281 * b0..13: length of ethernet frame
285 len
= header
& 0x3FFF;
287 /* bogus EEM payload? */
291 /* bogus ethernet frame? */
292 if (len
< (ETH_HLEN
+ ETH_FCS_LEN
))
296 * Treat the last payload differently: framework
297 * code expects our "fixup" to have stripped off
298 * headers, so "skb" is a data packet (or error).
299 * Else if it's not the last payload, keep "skb"
300 * for further processing.
302 is_last
= (len
== skb
->len
);
306 skb2
= skb_clone(skb
, GFP_ATOMIC
);
312 * The bmCRC helps to denote when the CRC field in
313 * the Ethernet frame contains a calculated CRC:
314 * bmCRC = 1 : CRC is calculated
315 * bmCRC = 0 : CRC = 0xDEADBEEF
317 if (header
& BIT(14)) {
318 crc
= get_unaligned_le32(skb2
->data
319 + len
- ETH_FCS_LEN
);
320 crc2
= ~crc32_le(~0, skb2
->data
, skb2
->len
323 crc
= get_unaligned_be32(skb2
->data
324 + len
- ETH_FCS_LEN
);
327 skb_trim(skb2
, len
- ETH_FCS_LEN
);
332 if (unlikely(crc
!= crc2
)) {
333 dev
->net
->stats
.rx_errors
++;
334 dev_kfree_skb_any(skb2
);
336 usbnet_skb_return(dev
, skb2
);
346 static const struct driver_info eem_info
= {
347 .description
= "CDC EEM Device",
348 .flags
= FLAG_ETHER
| FLAG_POINTTOPOINT
,
350 .rx_fixup
= eem_rx_fixup
,
351 .tx_fixup
= eem_tx_fixup
,
354 /*-------------------------------------------------------------------------*/
356 static const struct usb_device_id products
[] = {
358 USB_INTERFACE_INFO(USB_CLASS_COMM
, USB_CDC_SUBCLASS_EEM
,
360 .driver_info
= (unsigned long) &eem_info
,
363 /* EMPTY == end of list */
366 MODULE_DEVICE_TABLE(usb
, products
);
368 static struct usb_driver eem_driver
= {
370 .id_table
= products
,
371 .probe
= usbnet_probe
,
372 .disconnect
= usbnet_disconnect
,
373 .suspend
= usbnet_suspend
,
374 .resume
= usbnet_resume
,
375 .disable_hub_initiated_lpm
= 1,
378 module_usb_driver(eem_driver
);
380 MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
381 MODULE_DESCRIPTION("USB CDC EEM");
382 MODULE_LICENSE("GPL");