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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Ethernet interface part of the LG VL600 LTE modem (4G dongle)4 *5 * Copyright (C) 2011 Intel Corporation6 * Author: Andrzej Zaborowski <balrogg@gmail.com>7 */8#include <linux/etherdevice.h>9#include <linux/ethtool.h>10#include <linux/mii.h>11#include <linux/usb.h>12#include <linux/usb/cdc.h>13#include <linux/usb/usbnet.h>14#include <linux/if_ether.h>15#include <linux/if_arp.h>16#include <linux/inetdevice.h>17#include <linux/module.h>18 19/*20 * The device has a CDC ACM port for modem control (it claims to be21 * CDC ACM anyway) and a CDC Ethernet port for actual network data.22 * It will however ignore data on both ports that is not encapsulated23 * in a specific way, any data returned is also encapsulated the same24 * way. The headers don't seem to follow any popular standard.25 *26 * This driver adds and strips these headers from the ethernet frames27 * sent/received from the CDC Ethernet port. The proprietary header28 * replaces the standard ethernet header in a packet so only actual29 * ethernet frames are allowed. The headers allow some form of30 * multiplexing by using non standard values of the .h_proto field.31 * Windows/Mac drivers do send a couple of such frames to the device32 * during initialisation, with protocol set to 0x0906 or 0x0b06 and (what33 * seems to be) a flag in the .dummy_flags. This doesn't seem necessary34 * for modem operation but can possibly be used for GPS or other functions.35 */36 37struct vl600_frame_hdr {38 __le32 len;39 __le32 serial;40 __le32 pkt_cnt;41 __le32 dummy_flags;42 __le32 dummy;43 __le32 magic;44} __attribute__((packed));45 46struct vl600_pkt_hdr {47 __le32 dummy[2];48 __le32 len;49 __be16 h_proto;50} __attribute__((packed));51 52struct vl600_state {53 struct sk_buff *current_rx_buf;54};55 56static int vl600_bind(struct usbnet *dev, struct usb_interface *intf)57{58 int ret;59 struct vl600_state *s = kzalloc(sizeof(struct vl600_state), GFP_KERNEL);60 61 if (!s)62 return -ENOMEM;63 64 ret = usbnet_cdc_bind(dev, intf);65 if (ret) {66 kfree(s);67 return ret;68 }69 70 dev->driver_priv = s;71 72 /* ARP packets don't go through, but they're also of no use. The73 * subnet has only two hosts anyway: us and the gateway / DHCP74 * server (probably simulated by modem firmware or network operator)75 * whose address changes every time we connect to the intarwebz and76 * who doesn't bother answering ARP requests either. So hardware77 * addresses have no meaning, the destination and the source of every78 * packet depend only on whether it is on the IN or OUT endpoint. */79 dev->net->flags |= IFF_NOARP;80 /* IPv6 NDP relies on multicast. Enable it by default. */81 dev->net->flags |= IFF_MULTICAST;82 83 return ret;84}85 86static void vl600_unbind(struct usbnet *dev, struct usb_interface *intf)87{88 struct vl600_state *s = dev->driver_priv;89 90 dev_kfree_skb(s->current_rx_buf);91 kfree(s);92 93 return usbnet_cdc_unbind(dev, intf);94}95 96static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb)97{98 struct vl600_frame_hdr *frame;99 struct vl600_pkt_hdr *packet;100 struct ethhdr *ethhdr;101 int packet_len, count;102 struct sk_buff *buf = skb;103 struct sk_buff *clone;104 struct vl600_state *s = dev->driver_priv;105 106 /* Frame lengths are generally 4B multiplies but every couple of107 * hours there's an odd number of bytes sized yet correct frame,108 * so don't require this. */109 110 /* Allow a packet (or multiple packets batched together) to be111 * split across many frames. We don't allow a new batch to112 * begin in the same frame another one is ending however, and no113 * leading or trailing pad bytes. */114 if (s->current_rx_buf) {115 frame = (struct vl600_frame_hdr *) s->current_rx_buf->data;116 if (skb->len + s->current_rx_buf->len >117 le32_to_cpup(&frame->len)) {118 netif_err(dev, ifup, dev->net, "Fragment too long\n");119 dev->net->stats.rx_length_errors++;120 goto error;121 }122 123 buf = s->current_rx_buf;124 skb_put_data(buf, skb->data, skb->len);125 } else if (skb->len < 4) {126 netif_err(dev, ifup, dev->net, "Frame too short\n");127 dev->net->stats.rx_length_errors++;128 goto error;129 }130 131 frame = (struct vl600_frame_hdr *) buf->data;132 /* Yes, check that frame->magic == 0x53544448 (or 0x44544d48),133 * otherwise we may run out of memory w/a bad packet */134 if (ntohl(frame->magic) != 0x53544448 &&135 ntohl(frame->magic) != 0x44544d48)136 goto error;137 138 if (buf->len < sizeof(*frame) ||139 buf->len != le32_to_cpup(&frame->len)) {140 /* Save this fragment for later assembly */141 if (s->current_rx_buf)142 return 0;143 144 s->current_rx_buf = skb_copy_expand(skb, 0,145 le32_to_cpup(&frame->len), GFP_ATOMIC);146 if (!s->current_rx_buf)147 dev->net->stats.rx_errors++;148 149 return 0;150 }151 152 count = le32_to_cpup(&frame->pkt_cnt);153 154 skb_pull(buf, sizeof(*frame));155 156 while (count--) {157 if (buf->len < sizeof(*packet)) {158 netif_err(dev, ifup, dev->net, "Packet too short\n");159 goto error;160 }161 162 packet = (struct vl600_pkt_hdr *) buf->data;163 packet_len = sizeof(*packet) + le32_to_cpup(&packet->len);164 if (packet_len > buf->len) {165 netif_err(dev, ifup, dev->net,166 "Bad packet length stored in header\n");167 goto error;168 }169 170 /* Packet header is same size as the ethernet header171 * (sizeof(*packet) == sizeof(*ethhdr)), additionally172 * the h_proto field is in the same place so we just leave it173 * alone and fill in the remaining fields.174 */175 ethhdr = (struct ethhdr *) skb->data;176 if (be16_to_cpup(ðhdr->h_proto) == ETH_P_ARP &&177 buf->len > 0x26) {178 /* Copy the addresses from packet contents */179 memcpy(ethhdr->h_source,180 &buf->data[sizeof(*ethhdr) + 0x8],181 ETH_ALEN);182 memcpy(ethhdr->h_dest,183 &buf->data[sizeof(*ethhdr) + 0x12],184 ETH_ALEN);185 } else {186 eth_zero_addr(ethhdr->h_source);187 memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN);188 189 /* Inbound IPv6 packets have an IPv4 ethertype (0x800)190 * for some reason. Peek at the L3 header to check191 * for IPv6 packets, and set the ethertype to IPv6192 * (0x86dd) so Linux can understand it.193 */194 if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60)195 ethhdr->h_proto = htons(ETH_P_IPV6);196 }197 198 if (count) {199 /* Not the last packet in this batch */200 clone = skb_clone(buf, GFP_ATOMIC);201 if (!clone)202 goto error;203 204 skb_trim(clone, packet_len);205 usbnet_skb_return(dev, clone);206 207 skb_pull(buf, (packet_len + 3) & ~3);208 } else {209 skb_trim(buf, packet_len);210 211 if (s->current_rx_buf) {212 usbnet_skb_return(dev, buf);213 s->current_rx_buf = NULL;214 return 0;215 }216 217 return 1;218 }219 }220 221error:222 if (s->current_rx_buf) {223 dev_kfree_skb_any(s->current_rx_buf);224 s->current_rx_buf = NULL;225 }226 dev->net->stats.rx_errors++;227 return 0;228}229 230static struct sk_buff *vl600_tx_fixup(struct usbnet *dev,231 struct sk_buff *skb, gfp_t flags)232{233 struct sk_buff *ret;234 struct vl600_frame_hdr *frame;235 struct vl600_pkt_hdr *packet;236 static uint32_t serial = 1;237 int orig_len = skb->len - sizeof(struct ethhdr);238 int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3;239 240 frame = (struct vl600_frame_hdr *) skb->data;241 if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len))242 return skb; /* Already encapsulated? */243 244 if (skb->len < sizeof(struct ethhdr))245 /* Drop, device can only deal with ethernet packets */246 return NULL;247 248 if (!skb_cloned(skb)) {249 int headroom = skb_headroom(skb);250 int tailroom = skb_tailroom(skb);251 252 if (tailroom >= full_len - skb->len - sizeof(*frame) &&253 headroom >= sizeof(*frame))254 /* There's enough head and tail room */255 goto encapsulate;256 257 if (headroom + tailroom + skb->len >= full_len) {258 /* There's enough total room, just readjust */259 skb->data = memmove(skb->head + sizeof(*frame),260 skb->data, skb->len);261 skb_set_tail_pointer(skb, skb->len);262 goto encapsulate;263 }264 }265 266 /* Alloc a new skb with the required size */267 ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len -268 skb->len - sizeof(struct vl600_frame_hdr), flags);269 dev_kfree_skb_any(skb);270 if (!ret)271 return ret;272 skb = ret;273 274encapsulate:275 /* Packet header is same size as ethernet packet header276 * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the277 * h_proto field is in the same place so we just leave it alone and278 * overwrite the remaining fields.279 */280 packet = (struct vl600_pkt_hdr *) skb->data;281 /* The VL600 wants IPv6 packets to have an IPv4 ethertype282 * Since this modem only supports IPv4 and IPv6, just set all283 * frames to 0x0800 (ETH_P_IP)284 */285 packet->h_proto = htons(ETH_P_IP);286 memset(&packet->dummy, 0, sizeof(packet->dummy));287 packet->len = cpu_to_le32(orig_len);288 289 frame = skb_push(skb, sizeof(*frame));290 memset(frame, 0, sizeof(*frame));291 frame->len = cpu_to_le32(full_len);292 frame->serial = cpu_to_le32(serial++);293 frame->pkt_cnt = cpu_to_le32(1);294 295 if (skb->len < full_len) /* Pad */296 skb_put(skb, full_len - skb->len);297 298 return skb;299}300 301static const struct driver_info vl600_info = {302 .description = "LG VL600 modem",303 .flags = FLAG_RX_ASSEMBLE | FLAG_WWAN,304 .bind = vl600_bind,305 .unbind = vl600_unbind,306 .status = usbnet_cdc_status,307 .rx_fixup = vl600_rx_fixup,308 .tx_fixup = vl600_tx_fixup,309};310 311static const struct usb_device_id products[] = {312 {313 USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM,314 USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE),315 .driver_info = (unsigned long) &vl600_info,316 },317 {}, /* End */318};319MODULE_DEVICE_TABLE(usb, products);320 321static struct usb_driver lg_vl600_driver = {322 .name = "lg-vl600",323 .id_table = products,324 .probe = usbnet_probe,325 .disconnect = usbnet_disconnect,326 .suspend = usbnet_suspend,327 .resume = usbnet_resume,328 .disable_hub_initiated_lpm = 1,329};330 331module_usb_driver(lg_vl600_driver);332 333MODULE_AUTHOR("Anrzej Zaborowski");334MODULE_DESCRIPTION("LG-VL600 modem's ethernet link");335MODULE_LICENSE("GPL");336