/*
   * Copyright (C) ST-Ericsson AB 2010

   * Author:	Sjur Brendeland

   * License terms: GNU General Public License (GPL) version 2
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__

  #include <linux/stddef.h>
  #include <linux/spinlock.h>
  #include <linux/slab.h>
  #include <net/caif/caif_layer.h>
  #include <net/caif/cfsrvl.h>
  #include <net/caif/cfpkt.h>

  #define container_obj(layr) ((struct cfsrvl *) layr)
  
  #define DGM_CMD_BIT  0x80
  #define DGM_FLOW_OFF 0x81
  #define DGM_FLOW_ON  0x80

  #define DGM_MTU 1500

  
  static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
  static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
  
  struct cflayer *cfdgml_create(u8 channel_id, struct dev_info *dev_info)
  {

  	struct cfsrvl *dgm = kzalloc(sizeof(struct cfsrvl), GFP_ATOMIC);
  	if (!dgm)

  		return NULL;

  	caif_assert(offsetof(struct cfsrvl, layer) == 0);

  	cfsrvl_init(dgm, channel_id, dev_info, true);

  	dgm->layer.receive = cfdgml_receive;
  	dgm->layer.transmit = cfdgml_transmit;
  	snprintf(dgm->layer.name, CAIF_LAYER_NAME_SZ - 1, "dgm%d", channel_id);
  	dgm->layer.name[CAIF_LAYER_NAME_SZ - 1] = '\0';
  	return &dgm->layer;
  }
  
  static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt)
  {
  	u8 cmd = -1;
  	u8 dgmhdr[3];
  	int ret;
  	caif_assert(layr->up != NULL);
  	caif_assert(layr->receive != NULL);
  	caif_assert(layr->ctrlcmd != NULL);
  
  	if (cfpkt_extr_head(pkt, &cmd, 1) < 0) {

  		pr_err("Packet is erroneous!
  ");

  		cfpkt_destroy(pkt);
  		return -EPROTO;
  	}
  
  	if ((cmd & DGM_CMD_BIT) == 0) {
  		if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {

  			pr_err("Packet is erroneous!
  ");

  			cfpkt_destroy(pkt);
  			return -EPROTO;
  		}
  		ret = layr->up->receive(layr->up, pkt);
  		return ret;
  	}
  
  	switch (cmd) {
  	case DGM_FLOW_OFF:	/* FLOW OFF */
  		layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_OFF_IND, 0);
  		cfpkt_destroy(pkt);
  		return 0;
  	case DGM_FLOW_ON:	/* FLOW ON */
  		layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_ON_IND, 0);
  		cfpkt_destroy(pkt);
  		return 0;
  	default:
  		cfpkt_destroy(pkt);

  		pr_info("Unknown datagram control %d (0x%x)
  ", cmd, cmd);

  		return -EPROTO;
  	}
  }
  
  static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
  {

  	u8 packet_type;

  	u32 zero = 0;
  	struct caif_payload_info *info;
  	struct cfsrvl *service = container_obj(layr);
  	int ret;

  
  	if (!cfsrvl_ready(service, &ret)) {
  		cfpkt_destroy(pkt);

  		return ret;

  	}

  	/* STE Modem cannot handle more than 1500 bytes datagrams */

  	if (cfpkt_getlen(pkt) > DGM_MTU) {
  		cfpkt_destroy(pkt);

  		return -EMSGSIZE;

  	}

  	cfpkt_add_head(pkt, &zero, 3);
  	packet_type = 0x08; /* B9 set - UNCLASSIFIED */
  	cfpkt_add_head(pkt, &packet_type, 1);

  
  	/* Add info for MUX-layer to route the packet out. */
  	info = cfpkt_info(pkt);
  	info->channel_id = service->layer.id;
  	/* To optimize alignment, we add up the size of CAIF header
  	 * before payload.
  	 */
  	info->hdr_len = 4;
  	info->dev_info = &service->dev_info;

  	return layr->dn->transmit(layr->dn, pkt);

  }