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