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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* USB CDC EEM network interface driver
* Copyright (C) 2009 Oberthur Technologies
* by Omar Laazimani, Olivier Condemine
*/
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ctype.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/crc32.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/gfp.h>
#include <linux/if_vlan.h>
/*
* This driver is an implementation of the CDC "Ethernet Emulation
* Model" (EEM) specification, which encapsulates Ethernet frames
* for transport over USB using a simpler USB device model than the
* previous CDC "Ethernet Control Model" (ECM, or "CDC Ethernet").
*
* For details, see www.usb.org/developers/devclass_docs/CDC_EEM10.pdf
*
* This version has been tested with GIGAntIC WuaoW SIM Smart Card on 2.6.24,
* 2.6.27 and 2.6.30rc2 kernel.
* It has also been validated on Openmoko Om 2008.12 (based on 2.6.24 kernel).
* build on 23-April-2009
*/
#define EEM_HEAD 2 /* 2 byte header */
/*-------------------------------------------------------------------------*/
static void eem_linkcmd_complete(struct urb *urb)
{
dev_kfree_skb(urb->context);
usb_free_urb(urb);
}
static void eem_linkcmd(struct usbnet *dev, struct sk_buff *skb)
{
struct urb *urb;
int status;
urb = usb_alloc_urb(0, GFP_ATOMIC);
if (!urb)
goto fail;
usb_fill_bulk_urb(urb, dev->udev, dev->out,
skb->data, skb->len, eem_linkcmd_complete, skb);
status = usb_submit_urb(urb, GFP_ATOMIC);
if (status) {
usb_free_urb(urb);
fail:
dev_kfree_skb(skb);
netdev_warn(dev->net, "link cmd failure\n");
return;
}
}
static int eem_bind(struct usbnet *dev, struct usb_interface *intf)
{
int status = 0;
status = usbnet_get_endpoints(dev, intf);
if (status < 0)
return status;
/* no jumbogram (16K) support for now */
dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN + VLAN_HLEN;
dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
return 0;
}
/*
* EEM permits packing multiple Ethernet frames into USB transfers
* (a "bundle"), but for TX we don't try to do that.
*/
static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
gfp_t flags)
{
struct sk_buff *skb2 = NULL;
u16 len = skb->len;
u32 crc = 0;
int padlen = 0;
/* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
* zero, stick two bytes of zero length EEM packet on the end.
* Else the framework would add invalid single byte padding,
* since it can't know whether ZLPs will be handled right by
* all the relevant hardware and software.
*/
if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
padlen += 2;
if (!skb_cloned(skb)) {
int headroom = skb_headroom(skb);
int tailroom = skb_tailroom(skb);
if ((tailroom >= ETH_FCS_LEN + padlen) &&
(headroom >= EEM_HEAD))
goto done;
if ((headroom + tailroom)
> (EEM_HEAD + ETH_FCS_LEN + padlen)) {
skb->data = memmove(skb->head +
EEM_HEAD,
skb->data,
skb->len);
skb_set_tail_pointer(skb, len);
goto done;
}
}
skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
if (!skb2)
return NULL;
dev_kfree_skb_any(skb);
skb = skb2;
done:
/* we don't use the "no Ethernet CRC" option */
crc = crc32_le(~0, skb->data, skb->len);
crc = ~crc;
put_unaligned_le32(crc, skb_put(skb, 4));
/* EEM packet header format:
* b0..13: length of ethernet frame
* b14: bmCRC (1 == valid Ethernet CRC)
* b15: bmType (0 == data)
*/
len = skb->len;
put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));
/* Bundle a zero length EEM packet if needed */
if (padlen)
put_unaligned_le16(0, skb_put(skb, 2));
return skb;
}
static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
/*
* Our task here is to strip off framing, leaving skb with one
* data frame for the usbnet framework code to process. But we
* may have received multiple EEM payloads, or command payloads.
* So we must process _everything_ as if it's a header, except
* maybe the last data payload
*
* REVISIT the framework needs updating so that when we consume
* all payloads (the last or only message was a command, or a
* zero length EEM packet) that is not accounted as an rx_error.
*/
do {
struct sk_buff *skb2 = NULL;
u16 header;
u16 len = 0;
/* incomplete EEM header? */
if (skb->len < EEM_HEAD)
return 0;
/*
* EEM packet header format:
* b0..14: EEM type dependent (Data or Command)
* b15: bmType
*/
header = get_unaligned_le16(skb->data);
skb_pull(skb, EEM_HEAD);
/*
* The bmType bit helps to denote when EEM
* packet is data or command :
* bmType = 0 : EEM data payload
* bmType = 1 : EEM (link) command
*/
if (header & BIT(15)) {
u16 bmEEMCmd;
/*
* EEM (link) command packet:
* b0..10: bmEEMCmdParam
* b11..13: bmEEMCmd
* b14: bmReserved (must be 0)
* b15: 1 (EEM command)
*/
if (header & BIT(14)) {
netdev_dbg(dev->net, "reserved command %04x\n",
header);
continue;
}
bmEEMCmd = (header >> 11) & 0x7;
switch (bmEEMCmd) {
/* Responding to echo requests is mandatory. */
case 0: /* Echo command */
len = header & 0x7FF;
/* bogus command? */
if (skb->len < len)
return 0;
skb2 = skb_clone(skb, GFP_ATOMIC);
if (unlikely(!skb2))
goto next;
skb_trim(skb2, len);
put_unaligned_le16(BIT(15) | (1 << 11) | len,
skb_push(skb2, 2));
eem_linkcmd(dev, skb2);
break;
/*
* Host may choose to ignore hints.
* - suspend: peripheral ready to suspend
* - response: suggest N millisec polling
* - response complete: suggest N sec polling
*
* Suspend is reported and maybe heeded.
*/
case 2: /* Suspend hint */
usbnet_device_suggests_idle(dev);
continue;
case 3: /* Response hint */
case 4: /* Response complete hint */
continue;
/*
* Hosts should never receive host-to-peripheral
* or reserved command codes; or responses to an
* echo command we didn't send.
*/
case 1: /* Echo response */
case 5: /* Tickle */
default: /* reserved */
netdev_warn(dev->net,
"unexpected link command %d\n",
bmEEMCmd);
continue;
}
} else {
u32 crc, crc2;
int is_last;
/* zero length EEM packet? */
if (header == 0)
continue;
/*
* EEM data packet header :
* b0..13: length of ethernet frame
* b14: bmCRC
* b15: 0 (EEM data)
*/
len = header & 0x3FFF;
/* bogus EEM payload? */
if (skb->len < len)
return 0;
/* bogus ethernet frame? */
if (len < (ETH_HLEN + ETH_FCS_LEN))
goto next;
/*
* Treat the last payload differently: framework
* code expects our "fixup" to have stripped off
* headers, so "skb" is a data packet (or error).
* Else if it's not the last payload, keep "skb"
* for further processing.
*/
is_last = (len == skb->len);
if (is_last)
skb2 = skb;
else {
skb2 = skb_clone(skb, GFP_ATOMIC);
if (unlikely(!skb2))
return 0;
}
/*
* The bmCRC helps to denote when the CRC field in
* the Ethernet frame contains a calculated CRC:
* bmCRC = 1 : CRC is calculated
* bmCRC = 0 : CRC = 0xDEADBEEF
*/
if (header & BIT(14)) {
crc = get_unaligned_le32(skb2->data
+ len - ETH_FCS_LEN);
crc2 = ~crc32_le(~0, skb2->data, skb2->len
- ETH_FCS_LEN);
} else {
crc = get_unaligned_be32(skb2->data
+ len - ETH_FCS_LEN);
crc2 = 0xdeadbeef;
}
skb_trim(skb2, len - ETH_FCS_LEN);
if (is_last)
return crc == crc2;
if (unlikely(crc != crc2)) {
dev->net->stats.rx_errors++;
dev_kfree_skb_any(skb2);
} else
usbnet_skb_return(dev, skb2);
}
next:
skb_pull(skb, len);
} while (skb->len);
return 1;
}
static const struct driver_info eem_info = {
.description = "CDC EEM Device",
.flags = FLAG_ETHER | FLAG_POINTTOPOINT,
.bind = eem_bind,
.rx_fixup = eem_rx_fixup,
.tx_fixup = eem_tx_fixup,
};
/*-------------------------------------------------------------------------*/
static const struct usb_device_id products[] = {
{
USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
USB_CDC_PROTO_EEM),
.driver_info = (unsigned long) &eem_info,
},
{
/* EMPTY == end of list */
},
};
MODULE_DEVICE_TABLE(usb, products);
static struct usb_driver eem_driver = {
.name = "cdc_eem",
.id_table = products,
.probe = usbnet_probe,
.disconnect = usbnet_disconnect,
.suspend = usbnet_suspend,
.resume = usbnet_resume,
.disable_hub_initiated_lpm = 1,
};
module_usb_driver(eem_driver);
MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
MODULE_DESCRIPTION("USB CDC EEM");
MODULE_LICENSE("GPL");
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