net/caif/cfdgml.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) ST-Ericsson AB 2010
   4  * Author:      Sjur Brendeland
   5  */
   6
   7 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
   8
   9 #include <linux/stddef.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/slab.h>
  12 #include <net/caif/caif_layer.h>
  13 #include <net/caif/cfsrvl.h>
  14 #include <net/caif/cfpkt.h>
  15
  16
  17 #define container_obj(layr) ((struct cfsrvl *) layr)
  18
  19 #define DGM_CMD_BIT  0x80
  20 #define DGM_FLOW_OFF 0x81
  21 #define DGM_FLOW_ON  0x80
  22 #define DGM_MTU 1500
  23
  24 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
  25 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
  26
  27 struct cflayer *cfdgml_create(u8 channel_id, struct dev_info *dev_info)
  28 {
  29         struct cfsrvl *dgm = kzalloc(sizeof(struct cfsrvl), GFP_ATOMIC);
  30         if (!dgm)
  31                 return NULL;
  32         caif_assert(offsetof(struct cfsrvl, layer) == 0);
  33         cfsrvl_init(dgm, channel_id, dev_info, true);
  34         dgm->layer.receive = cfdgml_receive;
  35         dgm->layer.transmit = cfdgml_transmit;
  36         snprintf(dgm->layer.name, CAIF_LAYER_NAME_SZ, "dgm%d", channel_id);
  37         return &dgm->layer;
  38 }
  39
  40 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt)
  41 {
  42         u8 cmd = -1;
  43         u8 dgmhdr[3];
  44         int ret;
  45         caif_assert(layr->up != NULL);
  46         caif_assert(layr->receive != NULL);
  47         caif_assert(layr->ctrlcmd != NULL);
  48
  49         if (cfpkt_extr_head(pkt, &cmd, 1) < 0) {
  50                 pr_err("Packet is erroneous!\n");
  51                 cfpkt_destroy(pkt);
  52                 return -EPROTO;
  53         }
  54
  55         if ((cmd & DGM_CMD_BIT) == 0) {
  56                 if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {
  57                         pr_err("Packet is erroneous!\n");
  58                         cfpkt_destroy(pkt);
  59                         return -EPROTO;
  60                 }
  61                 ret = layr->up->receive(layr->up, pkt);
  62                 return ret;
  63         }
  64
  65         switch (cmd) {
  66         case DGM_FLOW_OFF:      /* FLOW OFF */
  67                 layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_OFF_IND, 0);
  68                 cfpkt_destroy(pkt);
  69                 return 0;
  70         case DGM_FLOW_ON:       /* FLOW ON */
  71                 layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_ON_IND, 0);
  72                 cfpkt_destroy(pkt);
  73                 return 0;
  74         default:
  75                 cfpkt_destroy(pkt);
  76                 pr_info("Unknown datagram control %d (0x%x)\n", cmd, cmd);
  77                 return -EPROTO;
  78         }
  79 }
  80
  81 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
  82 {
  83         u8 packet_type;
  84         u32 zero = 0;
  85         struct caif_payload_info *info;
  86         struct cfsrvl *service = container_obj(layr);
  87         int ret;
  88
  89         if (!cfsrvl_ready(service, &ret)) {
  90                 cfpkt_destroy(pkt);
  91                 return ret;
  92         }
  93
  94         /* STE Modem cannot handle more than 1500 bytes datagrams */
  95         if (cfpkt_getlen(pkt) > DGM_MTU) {
  96                 cfpkt_destroy(pkt);
  97                 return -EMSGSIZE;
  98         }
  99
 100         cfpkt_add_head(pkt, &zero, 3);
 101         packet_type = 0x08; /* B9 set - UNCLASSIFIED */
 102         cfpkt_add_head(pkt, &packet_type, 1);
 103
 104         /* Add info for MUX-layer to route the packet out. */
 105         info = cfpkt_info(pkt);
 106         info->channel_id = service->layer.id;
 107         /* To optimize alignment, we add up the size of CAIF header
 108          * before payload.
 109          */
 110         info->hdr_len = 4;
 111         info->dev_info = &service->dev_info;
 112         return layr->dn->transmit(layr->dn, pkt);
 113 }