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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Ethernet interface part of the LG VL600 LTE modem (4G dongle)
*
* Copyright (C) 2011 Intel Corporation
* Author: Andrzej Zaborowski <balrogg@gmail.com>
*/
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/inetdevice.h>
#include <linux/module.h>
/*
* The device has a CDC ACM port for modem control (it claims to be
* CDC ACM anyway) and a CDC Ethernet port for actual network data.
* It will however ignore data on both ports that is not encapsulated
* in a specific way, any data returned is also encapsulated the same
* way. The headers don't seem to follow any popular standard.
*
* This driver adds and strips these headers from the ethernet frames
* sent/received from the CDC Ethernet port. The proprietary header
* replaces the standard ethernet header in a packet so only actual
* ethernet frames are allowed. The headers allow some form of
* multiplexing by using non standard values of the .h_proto field.
* Windows/Mac drivers do send a couple of such frames to the device
* during initialisation, with protocol set to 0x0906 or 0x0b06 and (what
* seems to be) a flag in the .dummy_flags. This doesn't seem necessary
* for modem operation but can possibly be used for GPS or other funcitons.
*/
struct vl600_frame_hdr {
__le32 len;
__le32 serial;
__le32 pkt_cnt;
__le32 dummy_flags;
__le32 dummy;
__le32 magic;
} __attribute__((packed));
struct vl600_pkt_hdr {
__le32 dummy[2];
__le32 len;
__be16 h_proto;
} __attribute__((packed));
struct vl600_state {
struct sk_buff *current_rx_buf;
};
static int vl600_bind(struct usbnet *dev, struct usb_interface *intf)
{
int ret;
struct vl600_state *s = kzalloc(sizeof(struct vl600_state), GFP_KERNEL);
if (!s)
return -ENOMEM;
ret = usbnet_cdc_bind(dev, intf);
if (ret) {
kfree(s);
return ret;
}
dev->driver_priv = s;
/* ARP packets don't go through, but they're also of no use. The
* subnet has only two hosts anyway: us and the gateway / DHCP
* server (probably simulated by modem firmware or network operator)
* whose address changes everytime we connect to the intarwebz and
* who doesn't bother answering ARP requests either. So hardware
* addresses have no meaning, the destination and the source of every
* packet depend only on whether it is on the IN or OUT endpoint. */
dev->net->flags |= IFF_NOARP;
/* IPv6 NDP relies on multicast. Enable it by default. */
dev->net->flags |= IFF_MULTICAST;
return ret;
}
static void vl600_unbind(struct usbnet *dev, struct usb_interface *intf)
{
struct vl600_state *s = dev->driver_priv;
if (s->current_rx_buf)
dev_kfree_skb(s->current_rx_buf);
kfree(s);
return usbnet_cdc_unbind(dev, intf);
}
static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
struct vl600_frame_hdr *frame;
struct vl600_pkt_hdr *packet;
struct ethhdr *ethhdr;
int packet_len, count;
struct sk_buff *buf = skb;
struct sk_buff *clone;
struct vl600_state *s = dev->driver_priv;
/* Frame lengths are generally 4B multiplies but every couple of
* hours there's an odd number of bytes sized yet correct frame,
* so don't require this. */
/* Allow a packet (or multiple packets batched together) to be
* split across many frames. We don't allow a new batch to
* begin in the same frame another one is ending however, and no
* leading or trailing pad bytes. */
if (s->current_rx_buf) {
frame = (struct vl600_frame_hdr *) s->current_rx_buf->data;
if (skb->len + s->current_rx_buf->len >
le32_to_cpup(&frame->len)) {
netif_err(dev, ifup, dev->net, "Fragment too long\n");
dev->net->stats.rx_length_errors++;
goto error;
}
buf = s->current_rx_buf;
skb_put_data(buf, skb->data, skb->len);
} else if (skb->len < 4) {
netif_err(dev, ifup, dev->net, "Frame too short\n");
dev->net->stats.rx_length_errors++;
goto error;
}
frame = (struct vl600_frame_hdr *) buf->data;
/* Yes, check that frame->magic == 0x53544448 (or 0x44544d48),
* otherwise we may run out of memory w/a bad packet */
if (ntohl(frame->magic) != 0x53544448 &&
ntohl(frame->magic) != 0x44544d48)
goto error;
if (buf->len < sizeof(*frame) ||
buf->len != le32_to_cpup(&frame->len)) {
/* Save this fragment for later assembly */
if (s->current_rx_buf)
return 0;
s->current_rx_buf = skb_copy_expand(skb, 0,
le32_to_cpup(&frame->len), GFP_ATOMIC);
if (!s->current_rx_buf)
dev->net->stats.rx_errors++;
return 0;
}
count = le32_to_cpup(&frame->pkt_cnt);
skb_pull(buf, sizeof(*frame));
while (count--) {
if (buf->len < sizeof(*packet)) {
netif_err(dev, ifup, dev->net, "Packet too short\n");
goto error;
}
packet = (struct vl600_pkt_hdr *) buf->data;
packet_len = sizeof(*packet) + le32_to_cpup(&packet->len);
if (packet_len > buf->len) {
netif_err(dev, ifup, dev->net,
"Bad packet length stored in header\n");
goto error;
}
/* Packet header is same size as the ethernet header
* (sizeof(*packet) == sizeof(*ethhdr)), additionally
* the h_proto field is in the same place so we just leave it
* alone and fill in the remaining fields.
*/
ethhdr = (struct ethhdr *) skb->data;
if (be16_to_cpup(&ethhdr->h_proto) == ETH_P_ARP &&
buf->len > 0x26) {
/* Copy the addresses from packet contents */
memcpy(ethhdr->h_source,
&buf->data[sizeof(*ethhdr) + 0x8],
ETH_ALEN);
memcpy(ethhdr->h_dest,
&buf->data[sizeof(*ethhdr) + 0x12],
ETH_ALEN);
} else {
eth_zero_addr(ethhdr->h_source);
memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN);
/* Inbound IPv6 packets have an IPv4 ethertype (0x800)
* for some reason. Peek at the L3 header to check
* for IPv6 packets, and set the ethertype to IPv6
* (0x86dd) so Linux can understand it.
*/
if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60)
ethhdr->h_proto = htons(ETH_P_IPV6);
}
if (count) {
/* Not the last packet in this batch */
clone = skb_clone(buf, GFP_ATOMIC);
if (!clone)
goto error;
skb_trim(clone, packet_len);
usbnet_skb_return(dev, clone);
skb_pull(buf, (packet_len + 3) & ~3);
} else {
skb_trim(buf, packet_len);
if (s->current_rx_buf) {
usbnet_skb_return(dev, buf);
s->current_rx_buf = NULL;
return 0;
}
return 1;
}
}
error:
if (s->current_rx_buf) {
dev_kfree_skb_any(s->current_rx_buf);
s->current_rx_buf = NULL;
}
dev->net->stats.rx_errors++;
return 0;
}
static struct sk_buff *vl600_tx_fixup(struct usbnet *dev,
struct sk_buff *skb, gfp_t flags)
{
struct sk_buff *ret;
struct vl600_frame_hdr *frame;
struct vl600_pkt_hdr *packet;
static uint32_t serial = 1;
int orig_len = skb->len - sizeof(struct ethhdr);
int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3;
frame = (struct vl600_frame_hdr *) skb->data;
if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len))
return skb; /* Already encapsulated? */
if (skb->len < sizeof(struct ethhdr))
/* Drop, device can only deal with ethernet packets */
return NULL;
if (!skb_cloned(skb)) {
int headroom = skb_headroom(skb);
int tailroom = skb_tailroom(skb);
if (tailroom >= full_len - skb->len - sizeof(*frame) &&
headroom >= sizeof(*frame))
/* There's enough head and tail room */
goto encapsulate;
if (headroom + tailroom + skb->len >= full_len) {
/* There's enough total room, just readjust */
skb->data = memmove(skb->head + sizeof(*frame),
skb->data, skb->len);
skb_set_tail_pointer(skb, skb->len);
goto encapsulate;
}
}
/* Alloc a new skb with the required size */
ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len -
skb->len - sizeof(struct vl600_frame_hdr), flags);
dev_kfree_skb_any(skb);
if (!ret)
return ret;
skb = ret;
encapsulate:
/* Packet header is same size as ethernet packet header
* (sizeof(*packet) == sizeof(struct ethhdr)), additionally the
* h_proto field is in the same place so we just leave it alone and
* overwrite the remaining fields.
*/
packet = (struct vl600_pkt_hdr *) skb->data;
/* The VL600 wants IPv6 packets to have an IPv4 ethertype
* Since this modem only supports IPv4 and IPv6, just set all
* frames to 0x0800 (ETH_P_IP)
*/
packet->h_proto = htons(ETH_P_IP);
memset(&packet->dummy, 0, sizeof(packet->dummy));
packet->len = cpu_to_le32(orig_len);
frame = skb_push(skb, sizeof(*frame));
memset(frame, 0, sizeof(*frame));
frame->len = cpu_to_le32(full_len);
frame->serial = cpu_to_le32(serial++);
frame->pkt_cnt = cpu_to_le32(1);
if (skb->len < full_len) /* Pad */
skb_put(skb, full_len - skb->len);
return skb;
}
static const struct driver_info vl600_info = {
.description = "LG VL600 modem",
.flags = FLAG_RX_ASSEMBLE | FLAG_WWAN,
.bind = vl600_bind,
.unbind = vl600_unbind,
.status = usbnet_cdc_status,
.rx_fixup = vl600_rx_fixup,
.tx_fixup = vl600_tx_fixup,
};
static const struct usb_device_id products[] = {
{
USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM,
USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE),
.driver_info = (unsigned long) &vl600_info,
},
{}, /* End */
};
MODULE_DEVICE_TABLE(usb, products);
static struct usb_driver lg_vl600_driver = {
.name = "lg-vl600",
.id_table = products,
.probe = usbnet_probe,
.disconnect = usbnet_disconnect,
.suspend = usbnet_suspend,
.resume = usbnet_resume,
.disable_hub_initiated_lpm = 1,
};
module_usb_driver(lg_vl600_driver);
MODULE_AUTHOR("Anrzej Zaborowski");
MODULE_DESCRIPTION("LG-VL600 modem's ethernet link");
MODULE_LICENSE("GPL");
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