cfdgml.c

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/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:  Sjur Brendeland/[email protected]
 * 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!\n");
        cfpkt_destroy(pkt);
        return -EPROTO;
    }

    if ((cmd & DGM_CMD_BIT) == 0) {
        if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {
            pr_err("Packet is erroneous!\n");
            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)\n", 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);
}