/*
   * CAIF USB handler
   * Copyright (C) ST-Ericsson AB 2011
   * Author:	Sjur Brendeland/sjur.brandeland@stericsson.com
   * License terms: GNU General Public License (GPL) version 2
   *
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
  
  #include <linux/module.h>
  #include <linux/netdevice.h>
  #include <linux/slab.h>

  #include <linux/mii.h>
  #include <linux/usb.h>
  #include <linux/usb/usbnet.h>
  #include <net/netns/generic.h>
  #include <net/caif/caif_dev.h>
  #include <net/caif/caif_layer.h>
  #include <net/caif/cfpkt.h>
  #include <net/caif/cfcnfg.h>
  
  MODULE_LICENSE("GPL");
  
  #define CFUSB_PAD_DESCR_SZ 1	/* Alignment descriptor length */
  #define CFUSB_ALIGNMENT 4	/* Number of bytes to align. */
  #define CFUSB_MAX_HEADLEN (CFUSB_PAD_DESCR_SZ + CFUSB_ALIGNMENT-1)
  #define STE_USB_VID 0x04cc	/* USB Product ID for ST-Ericsson */

  #define STE_USB_PID_CAIF 0x230f	/* Product id for CAIF Modems */

  
  struct cfusbl {
  	struct cflayer layer;
  	u8 tx_eth_hdr[ETH_HLEN];
  };
  
  static bool pack_added;
  
  static int cfusbl_receive(struct cflayer *layr, struct cfpkt *pkt)
  {
  	u8 hpad;
  
  	/* Remove padding. */
  	cfpkt_extr_head(pkt, &hpad, 1);
  	cfpkt_extr_head(pkt, NULL, hpad);
  	return layr->up->receive(layr->up, pkt);
  }
  
  static int cfusbl_transmit(struct cflayer *layr, struct cfpkt *pkt)
  {
  	struct caif_payload_info *info;
  	u8 hpad;
  	u8 zeros[CFUSB_ALIGNMENT];
  	struct sk_buff *skb;
  	struct cfusbl *usbl = container_of(layr, struct cfusbl, layer);
  
  	skb = cfpkt_tonative(pkt);
  
  	skb_reset_network_header(skb);
  	skb->protocol = htons(ETH_P_IP);
  
  	info = cfpkt_info(pkt);
  	hpad = (info->hdr_len + CFUSB_PAD_DESCR_SZ) & (CFUSB_ALIGNMENT - 1);
  
  	if (skb_headroom(skb) < ETH_HLEN + CFUSB_PAD_DESCR_SZ + hpad) {
  		pr_warn("Headroom to small
  ");
  		kfree_skb(skb);
  		return -EIO;
  	}
  	memset(zeros, 0, hpad);
  
  	cfpkt_add_head(pkt, zeros, hpad);
  	cfpkt_add_head(pkt, &hpad, 1);
  	cfpkt_add_head(pkt, usbl->tx_eth_hdr, sizeof(usbl->tx_eth_hdr));
  	return layr->dn->transmit(layr->dn, pkt);
  }
  
  static void cfusbl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
  					int phyid)
  {
  	if (layr->up && layr->up->ctrlcmd)
  		layr->up->ctrlcmd(layr->up, ctrl, layr->id);
  }
  
  struct cflayer *cfusbl_create(int phyid, u8 ethaddr[ETH_ALEN],
  					u8 braddr[ETH_ALEN])
  {
  	struct cfusbl *this = kmalloc(sizeof(struct cfusbl), GFP_ATOMIC);
  
  	if (!this) {
  		pr_warn("Out of memory
  ");
  		return NULL;
  	}
  	caif_assert(offsetof(struct cfusbl, layer) == 0);
  
  	memset(this, 0, sizeof(struct cflayer));
  	this->layer.receive = cfusbl_receive;
  	this->layer.transmit = cfusbl_transmit;
  	this->layer.ctrlcmd = cfusbl_ctrlcmd;
  	snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "usb%d", phyid);
  	this->layer.id = phyid;
  
  	/*
  	 * Construct TX ethernet header:
  	 *	0-5	destination address
  	 *	5-11	source address
  	 *	12-13	protocol type
  	 */
  	memcpy(&this->tx_eth_hdr[ETH_ALEN], braddr, ETH_ALEN);
  	memcpy(&this->tx_eth_hdr[ETH_ALEN], ethaddr, ETH_ALEN);
  	this->tx_eth_hdr[12] = cpu_to_be16(ETH_P_802_EX1) & 0xff;
  	this->tx_eth_hdr[13] = (cpu_to_be16(ETH_P_802_EX1) >> 8) & 0xff;
  	pr_debug("caif ethernet TX-header dst:%pM src:%pM type:%02x%02x
  ",
  			this->tx_eth_hdr, this->tx_eth_hdr + ETH_ALEN,
  			this->tx_eth_hdr[12], this->tx_eth_hdr[13]);
  
  	return (struct cflayer *) this;
  }
  
  static struct packet_type caif_usb_type __read_mostly = {
  	.type = cpu_to_be16(ETH_P_802_EX1),
  };
  
  static int cfusbl_device_notify(struct notifier_block *me, unsigned long what,
  			      void *arg)
  {
  	struct net_device *dev = arg;
  	struct caif_dev_common common;
  	struct cflayer *layer, *link_support;

  	struct usbnet *usbnet;
  	struct usb_device *usbdev;

  	struct ethtool_drvinfo drvinfo;
  
  	/*
  	 * Quirks: High-jack ethtool to find if we have a NCM device,
  	 * and find it's VID/PID.
  	 */
  	if (dev->ethtool_ops == NULL || dev->ethtool_ops->get_drvinfo == NULL)
  		return 0;
  
  	dev->ethtool_ops->get_drvinfo(dev, &drvinfo);
  	if (strncmp(drvinfo.driver, "cdc_ncm", 7) != 0)
  		return 0;

  	usbnet = netdev_priv(dev);
  	usbdev = usbnet->udev;

  	pr_debug("USB CDC NCM device VID:0x%4x PID:0x%4x
  ",
  		le16_to_cpu(usbdev->descriptor.idVendor),
  		le16_to_cpu(usbdev->descriptor.idProduct));
  
  	/* Check for VID/PID that supports CAIF */
  	if (!(le16_to_cpu(usbdev->descriptor.idVendor) == STE_USB_VID &&
  		le16_to_cpu(usbdev->descriptor.idProduct) == STE_USB_PID_CAIF))
  		return 0;
  
  	if (what == NETDEV_UNREGISTER)
  		module_put(THIS_MODULE);
  
  	if (what != NETDEV_REGISTER)
  		return 0;
  
  	__module_get(THIS_MODULE);
  
  	memset(&common, 0, sizeof(common));
  	common.use_frag = false;
  	common.use_fcs = false;
  	common.use_stx = false;
  	common.link_select = CAIF_LINK_HIGH_BANDW;
  	common.flowctrl = NULL;
  
  	link_support = cfusbl_create(dev->ifindex, dev->dev_addr,
  					dev->broadcast);
  
  	if (!link_support)
  		return -ENOMEM;
  
  	if (dev->num_tx_queues > 1)
  		pr_warn("USB device uses more than one tx queue
  ");
  
  	caif_enroll_dev(dev, &common, link_support, CFUSB_MAX_HEADLEN,
  			&layer, &caif_usb_type.func);
  	if (!pack_added)
  		dev_add_pack(&caif_usb_type);

  	pack_added = true;

  
  	strncpy(layer->name, dev->name,
  			sizeof(layer->name) - 1);
  	layer->name[sizeof(layer->name) - 1] = 0;
  
  	return 0;
  }
  
  static struct notifier_block caif_device_notifier = {
  	.notifier_call = cfusbl_device_notify,
  	.priority = 0,
  };
  
  static int __init cfusbl_init(void)
  {
  	return register_netdevice_notifier(&caif_device_notifier);
  }
  
  static void __exit cfusbl_exit(void)
  {
  	unregister_netdevice_notifier(&caif_device_notifier);
  	dev_remove_pack(&caif_usb_type);
  }
  
  module_init(cfusbl_init);
  module_exit(cfusbl_exit);