cffrml.c

Go to the documentation of this file.

/*
 * CAIF Framing Layer.
 *
 * 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 <linux/crc-ccitt.h>
#include <linux/netdevice.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfpkt.h>
#include <net/caif/cffrml.h>

#define container_obj(layr) container_of(layr, struct cffrml, layer)

struct cffrml {
    struct cflayer layer;
    bool dofcs;     /* !< FCS active */
    int __percpu        *pcpu_refcnt;
};

static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt);
static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt);
static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
                int phyid);

static u32 cffrml_rcv_error;
static u32 cffrml_rcv_checsum_error;
struct cflayer *cffrml_create(u16 phyid, bool use_fcs)
{
    struct cffrml *this = kzalloc(sizeof(struct cffrml), GFP_ATOMIC);
    if (!this)
        return NULL;
    this->pcpu_refcnt = alloc_percpu(int);
    if (this->pcpu_refcnt == NULL) {
        kfree(this);
        return NULL;
    }

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

    this->layer.receive = cffrml_receive;
    this->layer.transmit = cffrml_transmit;
    this->layer.ctrlcmd = cffrml_ctrlcmd;
    snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "frm%d", phyid);
    this->dofcs = use_fcs;
    this->layer.id = phyid;
    return (struct cflayer *) this;
}

void cffrml_free(struct cflayer *layer)
{
    struct cffrml *this = container_obj(layer);
    free_percpu(this->pcpu_refcnt);
    kfree(layer);
}

void cffrml_set_uplayer(struct cflayer *this, struct cflayer *up)
{
    this->up = up;
}

void cffrml_set_dnlayer(struct cflayer *this, struct cflayer *dn)
{
    this->dn = dn;
}

static u16 cffrml_checksum(u16 chks, void *buf, u16 len)
{
    /* FIXME: FCS should be moved to glue in order to use OS-Specific
     * solutions
     */
    return crc_ccitt(chks, buf, len);
}

static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt)
{
    u16 tmp;
    u16 len;
    u16 hdrchks;
    u16 pktchks;
    struct cffrml *this;
    this = container_obj(layr);

    cfpkt_extr_head(pkt, &tmp, 2);
    len = le16_to_cpu(tmp);

    /* Subtract for FCS on length if FCS is not used. */
    if (!this->dofcs)
        len -= 2;

    if (cfpkt_setlen(pkt, len) < 0) {
        ++cffrml_rcv_error;
        pr_err("Framing length error (%d)\n", len);
        cfpkt_destroy(pkt);
        return -EPROTO;
    }
    /*
     * Don't do extract if FCS is false, rather do setlen - then we don't
     * get a cache-miss.
     */
    if (this->dofcs) {
        cfpkt_extr_trail(pkt, &tmp, 2);
        hdrchks = le16_to_cpu(tmp);
        pktchks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
        if (pktchks != hdrchks) {
            cfpkt_add_trail(pkt, &tmp, 2);
            ++cffrml_rcv_error;
            ++cffrml_rcv_checsum_error;
            pr_info("Frame checksum error (0x%x != 0x%x)\n",
                hdrchks, pktchks);
            return -EILSEQ;
        }
    }
    if (cfpkt_erroneous(pkt)) {
        ++cffrml_rcv_error;
        pr_err("Packet is erroneous!\n");
        cfpkt_destroy(pkt);
        return -EPROTO;
    }

    if (layr->up == NULL) {
        pr_err("Layr up is missing!\n");
        cfpkt_destroy(pkt);
        return -EINVAL;
    }

    return layr->up->receive(layr->up, pkt);
}

static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt)
{
    u16 chks;
    u16 len;
    __le16 data;

    struct cffrml *this = container_obj(layr);
    if (this->dofcs) {
        chks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
        data = cpu_to_le16(chks);
        cfpkt_add_trail(pkt, &data, 2);
    } else {
        cfpkt_pad_trail(pkt, 2);
    }
    len = cfpkt_getlen(pkt);
    data = cpu_to_le16(len);
    cfpkt_add_head(pkt, &data, 2);
    cfpkt_info(pkt)->hdr_len += 2;
    if (cfpkt_erroneous(pkt)) {
        pr_err("Packet is erroneous!\n");
        cfpkt_destroy(pkt);
        return -EPROTO;
    }

    if (layr->dn == NULL) {
        cfpkt_destroy(pkt);
        return -ENODEV;

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

static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
                    int phyid)
{
    if (layr->up && layr->up->ctrlcmd)
        layr->up->ctrlcmd(layr->up, ctrl, layr->id);
}

void cffrml_put(struct cflayer *layr)
{
    struct cffrml *this = container_obj(layr);
    if (layr != NULL && this->pcpu_refcnt != NULL)
        this_cpu_dec(*this->pcpu_refcnt);
}

void cffrml_hold(struct cflayer *layr)
{
    struct cffrml *this = container_obj(layr);
    if (layr != NULL && this->pcpu_refcnt != NULL)
        this_cpu_inc(*this->pcpu_refcnt);
}

int cffrml_refcnt_read(struct cflayer *layr)
{
    int i, refcnt = 0;
    struct cffrml *this = container_obj(layr);
    for_each_possible_cpu(i)
        refcnt += *per_cpu_ptr(this->pcpu_refcnt, i);
    return refcnt;
}