net/caif/cfdgml.c

   1 /*
   2  * Copyright (C) ST-Ericsson AB 2010
   3  * Author:      Sjur Brendeland/sjur.brandeland@stericsson.com
   4  * License terms: GNU General Public License (GPL) version 2
   5  */
   6
   7 #include <linux/stddef.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/slab.h>
  10 #include <net/caif/caif_layer.h>
  11 #include <net/caif/cfsrvl.h>
  12 #include <net/caif/cfpkt.h>
  13
  14 #define container_obj(layr) ((struct cfsrvl *) layr)
  15
  16 #define DGM_CMD_BIT  0x80
  17 #define DGM_FLOW_OFF 0x81
  18 #define DGM_FLOW_ON  0x80
  19 #define DGM_CTRL_PKT_SIZE 1
  20 #define DGM_MTU 1500
  21
  22 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
  23 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
  24
  25 struct cflayer *cfdgml_create(u8 channel_id, struct dev_info *dev_info)
  26 {
  27         struct cfsrvl *dgm = kmalloc(sizeof(struct cfsrvl), GFP_ATOMIC);
  28         if (!dgm) {
  29                 pr_warning("CAIF: %s(): Out of memory\n", __func__);
  30                 return NULL;
  31         }
  32         caif_assert(offsetof(struct cfsrvl, layer) == 0);
  33         memset(dgm, 0, sizeof(struct cfsrvl));
  34         cfsrvl_init(dgm, channel_id, dev_info, true);
  35         dgm->layer.receive = cfdgml_receive;
  36         dgm->layer.transmit = cfdgml_transmit;
  37         snprintf(dgm->layer.name, CAIF_LAYER_NAME_SZ - 1, "dgm%d", channel_id);
  38         dgm->layer.name[CAIF_LAYER_NAME_SZ - 1] = '\0';
  39         return &dgm->layer;
  40 }
  41
  42 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt)
  43 {
  44         u8 cmd = -1;
  45         u8 dgmhdr[3];
  46         int ret;
  47         caif_assert(layr->up != NULL);
  48         caif_assert(layr->receive != NULL);
  49         caif_assert(layr->ctrlcmd != NULL);
  50
  51         if (cfpkt_extr_head(pkt, &cmd, 1) < 0) {
  52                 pr_err("CAIF: %s(): Packet is erroneous!\n", __func__);
  53                 cfpkt_destroy(pkt);
  54                 return -EPROTO;
  55         }
  56
  57         if ((cmd & DGM_CMD_BIT) == 0) {
  58                 if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {
  59                         pr_err("CAIF: %s(): Packet is erroneous!\n", __func__);
  60                         cfpkt_destroy(pkt);
  61                         return -EPROTO;
  62                 }
  63                 ret = layr->up->receive(layr->up, pkt);
  64                 return ret;
  65         }
  66
  67         switch (cmd) {
  68         case DGM_FLOW_OFF:      /* FLOW OFF */
  69                 layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_OFF_IND, 0);
  70                 cfpkt_destroy(pkt);
  71                 return 0;
  72         case DGM_FLOW_ON:       /* FLOW ON */
  73                 layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_ON_IND, 0);
  74                 cfpkt_destroy(pkt);
  75                 return 0;
  76         default:
  77                 cfpkt_destroy(pkt);
  78                 pr_info("CAIF: %s(): Unknown datagram control %d (0x%x)\n",
  79                         __func__, cmd, cmd);
  80                 return -EPROTO;
  81         }
  82 }
  83
  84 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
  85 {
  86         u32 zero = 0;
  87         struct caif_payload_info *info;
  88         struct cfsrvl *service = container_obj(layr);
  89         int ret;
  90         if (!cfsrvl_ready(service, &ret))
  91                 return ret;
  92
  93         /* STE Modem cannot handle more than 1500 bytes datagrams */
  94         if (cfpkt_getlen(pkt) > DGM_MTU)
  95                 return -EMSGSIZE;
  96
  97         cfpkt_add_head(pkt, &zero, 4);
  98
  99         /* Add info for MUX-layer to route the packet out. */
 100         info = cfpkt_info(pkt);
 101         info->channel_id = service->layer.id;
 102         /* To optimize alignment, we add up the size of CAIF header
 103          * before payload.
 104          */
 105         info->hdr_len = 4;
 106         info->dev_info = &service->dev_info;
 107         ret = layr->dn->transmit(layr->dn, pkt);
 108         if (ret < 0) {
 109                 u32 tmp32;
 110                 cfpkt_extr_head(pkt, &tmp32, 4);
 111         }
 112         return ret;
 113 }