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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * USB CDC EEM network interface driver4 * Copyright (C) 2009 Oberthur Technologies5 * by Omar Laazimani, Olivier Condemine6 */7 8#include <linux/module.h>9#include <linux/netdevice.h>10#include <linux/etherdevice.h>11#include <linux/ctype.h>12#include <linux/ethtool.h>13#include <linux/workqueue.h>14#include <linux/mii.h>15#include <linux/usb.h>16#include <linux/crc32.h>17#include <linux/usb/cdc.h>18#include <linux/usb/usbnet.h>19#include <linux/gfp.h>20#include <linux/if_vlan.h>21 22 23/*24 * This driver is an implementation of the CDC "Ethernet Emulation25 * Model" (EEM) specification, which encapsulates Ethernet frames26 * for transport over USB using a simpler USB device model than the27 * previous CDC "Ethernet Control Model" (ECM, or "CDC Ethernet").28 *29 * For details, see https://usb.org/sites/default/files/CDC_EEM10.pdf30 *31 * This version has been tested with GIGAntIC WuaoW SIM Smart Card on 2.6.24,32 * 2.6.27 and 2.6.30rc2 kernel.33 * It has also been validated on Openmoko Om 2008.12 (based on 2.6.24 kernel).34 * build on 23-April-200935 */36 37#define EEM_HEAD 2 /* 2 byte header */38 39/*-------------------------------------------------------------------------*/40 41static void eem_linkcmd_complete(struct urb *urb)42{43 dev_kfree_skb(urb->context);44 usb_free_urb(urb);45}46 47static void eem_linkcmd(struct usbnet *dev, struct sk_buff *skb)48{49 struct urb *urb;50 int status;51 52 urb = usb_alloc_urb(0, GFP_ATOMIC);53 if (!urb)54 goto fail;55 56 usb_fill_bulk_urb(urb, dev->udev, dev->out,57 skb->data, skb->len, eem_linkcmd_complete, skb);58 59 status = usb_submit_urb(urb, GFP_ATOMIC);60 if (status) {61 usb_free_urb(urb);62fail:63 dev_kfree_skb(skb);64 netdev_warn(dev->net, "link cmd failure\n");65 return;66 }67}68 69static int eem_bind(struct usbnet *dev, struct usb_interface *intf)70{71 int status = 0;72 73 status = usbnet_get_endpoints(dev, intf);74 if (status < 0)75 return status;76 77 /* no jumbogram (16K) support for now */78 79 dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN + VLAN_HLEN;80 dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;81 82 return 0;83}84 85/*86 * EEM permits packing multiple Ethernet frames into USB transfers87 * (a "bundle"), but for TX we don't try to do that.88 */89static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,90 gfp_t flags)91{92 struct sk_buff *skb2 = NULL;93 u16 len = skb->len;94 u32 crc = 0;95 int padlen = 0;96 97 /* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is98 * zero, stick two bytes of zero length EEM packet on the end.99 * Else the framework would add invalid single byte padding,100 * since it can't know whether ZLPs will be handled right by101 * all the relevant hardware and software.102 */103 if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))104 padlen += 2;105 106 if (!skb_cloned(skb)) {107 int headroom = skb_headroom(skb);108 int tailroom = skb_tailroom(skb);109 110 if ((tailroom >= ETH_FCS_LEN + padlen) &&111 (headroom >= EEM_HEAD))112 goto done;113 114 if ((headroom + tailroom)115 > (EEM_HEAD + ETH_FCS_LEN + padlen)) {116 skb->data = memmove(skb->head +117 EEM_HEAD,118 skb->data,119 skb->len);120 skb_set_tail_pointer(skb, len);121 goto done;122 }123 }124 125 skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);126 dev_kfree_skb_any(skb);127 if (!skb2)128 return NULL;129 130 skb = skb2;131 132done:133 /* we don't use the "no Ethernet CRC" option */134 crc = crc32_le(~0, skb->data, skb->len);135 crc = ~crc;136 137 put_unaligned_le32(crc, skb_put(skb, 4));138 139 /* EEM packet header format:140 * b0..13: length of ethernet frame141 * b14: bmCRC (1 == valid Ethernet CRC)142 * b15: bmType (0 == data)143 */144 len = skb->len;145 put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));146 147 /* Bundle a zero length EEM packet if needed */148 if (padlen)149 put_unaligned_le16(0, skb_put(skb, 2));150 151 return skb;152}153 154static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)155{156 /*157 * Our task here is to strip off framing, leaving skb with one158 * data frame for the usbnet framework code to process. But we159 * may have received multiple EEM payloads, or command payloads.160 * So we must process _everything_ as if it's a header, except161 * maybe the last data payload162 *163 * REVISIT the framework needs updating so that when we consume164 * all payloads (the last or only message was a command, or a165 * zero length EEM packet) that is not accounted as an rx_error.166 */167 do {168 struct sk_buff *skb2 = NULL;169 u16 header;170 u16 len = 0;171 172 /* incomplete EEM header? */173 if (skb->len < EEM_HEAD)174 return 0;175 176 /*177 * EEM packet header format:178 * b0..14: EEM type dependent (Data or Command)179 * b15: bmType180 */181 header = get_unaligned_le16(skb->data);182 skb_pull(skb, EEM_HEAD);183 184 /*185 * The bmType bit helps to denote when EEM186 * packet is data or command :187 * bmType = 0 : EEM data payload188 * bmType = 1 : EEM (link) command189 */190 if (header & BIT(15)) {191 u16 bmEEMCmd;192 193 /*194 * EEM (link) command packet:195 * b0..10: bmEEMCmdParam196 * b11..13: bmEEMCmd197 * b14: bmReserved (must be 0)198 * b15: 1 (EEM command)199 */200 if (header & BIT(14)) {201 netdev_dbg(dev->net, "reserved command %04x\n",202 header);203 continue;204 }205 206 bmEEMCmd = (header >> 11) & 0x7;207 switch (bmEEMCmd) {208 209 /* Responding to echo requests is mandatory. */210 case 0: /* Echo command */211 len = header & 0x7FF;212 213 /* bogus command? */214 if (skb->len < len)215 return 0;216 217 skb2 = skb_clone(skb, GFP_ATOMIC);218 if (unlikely(!skb2))219 goto next;220 skb_trim(skb2, len);221 put_unaligned_le16(BIT(15) | BIT(11) | len,222 skb_push(skb2, 2));223 eem_linkcmd(dev, skb2);224 break;225 226 /*227 * Host may choose to ignore hints.228 * - suspend: peripheral ready to suspend229 * - response: suggest N millisec polling230 * - response complete: suggest N sec polling231 *232 * Suspend is reported and maybe heeded.233 */234 case 2: /* Suspend hint */235 usbnet_device_suggests_idle(dev);236 continue;237 case 3: /* Response hint */238 case 4: /* Response complete hint */239 continue;240 241 /*242 * Hosts should never receive host-to-peripheral243 * or reserved command codes; or responses to an244 * echo command we didn't send.245 */246 case 1: /* Echo response */247 case 5: /* Tickle */248 default: /* reserved */249 netdev_warn(dev->net,250 "unexpected link command %d\n",251 bmEEMCmd);252 continue;253 }254 255 } else {256 u32 crc, crc2;257 int is_last;258 259 /* zero length EEM packet? */260 if (header == 0)261 continue;262 263 /*264 * EEM data packet header :265 * b0..13: length of ethernet frame266 * b14: bmCRC267 * b15: 0 (EEM data)268 */269 len = header & 0x3FFF;270 271 /* bogus EEM payload? */272 if (skb->len < len)273 return 0;274 275 /* bogus ethernet frame? */276 if (len < (ETH_HLEN + ETH_FCS_LEN))277 goto next;278 279 /*280 * Treat the last payload differently: framework281 * code expects our "fixup" to have stripped off282 * headers, so "skb" is a data packet (or error).283 * Else if it's not the last payload, keep "skb"284 * for further processing.285 */286 is_last = (len == skb->len);287 if (is_last)288 skb2 = skb;289 else {290 skb2 = skb_clone(skb, GFP_ATOMIC);291 if (unlikely(!skb2))292 return 0;293 }294 295 /*296 * The bmCRC helps to denote when the CRC field in297 * the Ethernet frame contains a calculated CRC:298 * bmCRC = 1 : CRC is calculated299 * bmCRC = 0 : CRC = 0xDEADBEEF300 */301 if (header & BIT(14)) {302 crc = get_unaligned_le32(skb2->data303 + len - ETH_FCS_LEN);304 crc2 = ~crc32_le(~0, skb2->data, skb2->len305 - ETH_FCS_LEN);306 } else {307 crc = get_unaligned_be32(skb2->data308 + len - ETH_FCS_LEN);309 crc2 = 0xdeadbeef;310 }311 skb_trim(skb2, len - ETH_FCS_LEN);312 313 if (is_last)314 return crc == crc2;315 316 if (unlikely(crc != crc2)) {317 dev->net->stats.rx_errors++;318 dev_kfree_skb_any(skb2);319 } else320 usbnet_skb_return(dev, skb2);321 }322 323next:324 skb_pull(skb, len);325 } while (skb->len);326 327 return 1;328}329 330static const struct driver_info eem_info = {331 .description = "CDC EEM Device",332 .flags = FLAG_ETHER | FLAG_POINTTOPOINT,333 .bind = eem_bind,334 .rx_fixup = eem_rx_fixup,335 .tx_fixup = eem_tx_fixup,336};337 338/*-------------------------------------------------------------------------*/339 340static const struct usb_device_id products[] = {341{342 USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,343 USB_CDC_PROTO_EEM),344 .driver_info = (unsigned long) &eem_info,345},346{347 /* EMPTY == end of list */348},349};350MODULE_DEVICE_TABLE(usb, products);351 352static struct usb_driver eem_driver = {353 .name = "cdc_eem",354 .id_table = products,355 .probe = usbnet_probe,356 .disconnect = usbnet_disconnect,357 .suspend = usbnet_suspend,358 .resume = usbnet_resume,359 .disable_hub_initiated_lpm = 1,360};361 362module_usb_driver(eem_driver);363 364MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");365MODULE_DESCRIPTION("USB CDC EEM");366MODULE_LICENSE("GPL");367