net/caif/cfdgml.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) ST-Ericsson AB 2010
0004  * Author:  Sjur Brendeland
0005  */
0006
0007 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
0008
0009 #include <linux/stddef.h>
0010 #include <linux/spinlock.h>
0011 #include <linux/slab.h>
0012 #include <net/caif/caif_layer.h>
0013 #include <net/caif/cfsrvl.h>
0014 #include <net/caif/cfpkt.h>
0015
0016
0017 #define container_obj(layr) ((struct cfsrvl *) layr)
0018
0019 #define DGM_CMD_BIT  0x80
0020 #define DGM_FLOW_OFF 0x81
0021 #define DGM_FLOW_ON  0x80
0022 #define DGM_MTU 1500
0023
0024 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
0025 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
0026
0027 struct cflayer *cfdgml_create(u8 channel_id, struct dev_info *dev_info)
0028 {
0029     struct cfsrvl *dgm = kzalloc(sizeof(struct cfsrvl), GFP_ATOMIC);
0030     if (!dgm)
0031         return NULL;
0032     caif_assert(offsetof(struct cfsrvl, layer) == 0);
0033     cfsrvl_init(dgm, channel_id, dev_info, true);
0034     dgm->layer.receive = cfdgml_receive;
0035     dgm->layer.transmit = cfdgml_transmit;
0036     snprintf(dgm->layer.name, CAIF_LAYER_NAME_SZ, "dgm%d", channel_id);
0037     return &dgm->layer;
0038 }
0039
0040 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt)
0041 {
0042     u8 cmd = -1;
0043     u8 dgmhdr[3];
0044     int ret;
0045     caif_assert(layr->up != NULL);
0046     caif_assert(layr->receive != NULL);
0047     caif_assert(layr->ctrlcmd != NULL);
0048
0049     if (cfpkt_extr_head(pkt, &cmd, 1) < 0) {
0050         pr_err("Packet is erroneous!\n");
0051         cfpkt_destroy(pkt);
0052         return -EPROTO;
0053     }
0054
0055     if ((cmd & DGM_CMD_BIT) == 0) {
0056         if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {
0057             pr_err("Packet is erroneous!\n");
0058             cfpkt_destroy(pkt);
0059             return -EPROTO;
0060         }
0061         ret = layr->up->receive(layr->up, pkt);
0062         return ret;
0063     }
0064
0065     switch (cmd) {
0066     case DGM_FLOW_OFF:  /* FLOW OFF */
0067         layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_OFF_IND, 0);
0068         cfpkt_destroy(pkt);
0069         return 0;
0070     case DGM_FLOW_ON:   /* FLOW ON */
0071         layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_ON_IND, 0);
0072         cfpkt_destroy(pkt);
0073         return 0;
0074     default:
0075         cfpkt_destroy(pkt);
0076         pr_info("Unknown datagram control %d (0x%x)\n", cmd, cmd);
0077         return -EPROTO;
0078     }
0079 }
0080
0081 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
0082 {
0083     u8 packet_type;
0084     u32 zero = 0;
0085     struct caif_payload_info *info;
0086     struct cfsrvl *service = container_obj(layr);
0087     int ret;
0088
0089     if (!cfsrvl_ready(service, &ret)) {
0090         cfpkt_destroy(pkt);
0091         return ret;
0092     }
0093
0094     /* STE Modem cannot handle more than 1500 bytes datagrams */
0095     if (cfpkt_getlen(pkt) > DGM_MTU) {
0096         cfpkt_destroy(pkt);
0097         return -EMSGSIZE;
0098     }
0099
0100     cfpkt_add_head(pkt, &zero, 3);
0101     packet_type = 0x08; /* B9 set - UNCLASSIFIED */
0102     cfpkt_add_head(pkt, &packet_type, 1);
0103
0104     /* Add info for MUX-layer to route the packet out. */
0105     info = cfpkt_info(pkt);
0106     info->channel_id = service->layer.id;
0107     /* To optimize alignment, we add up the size of CAIF header
0108      * before payload.
0109      */
0110     info->hdr_len = 4;
0111     info->dev_info = &service->dev_info;
0112     return layr->dn->transmit(layr->dn, pkt);
0113 }