linux/net/caif/cfserl.c
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   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/cfpkt.h>
  12#include <net/caif/cfserl.h>
  13
  14#define container_obj(layr) ((struct cfserl *) layr)
  15
  16#define CFSERL_STX 0x02
  17#define CAIF_MINIUM_PACKET_SIZE 4
  18struct cfserl {
  19        struct cflayer layer;
  20        struct cfpkt *incomplete_frm;
  21        /* Protects parallel processing of incoming packets */
  22        spinlock_t sync;
  23        bool usestx;
  24};
  25#define STXLEN(layr) (layr->usestx ? 1 : 0)
  26
  27static int cfserl_receive(struct cflayer *layr, struct cfpkt *pkt);
  28static int cfserl_transmit(struct cflayer *layr, struct cfpkt *pkt);
  29static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
  30                                int phyid);
  31
  32struct cflayer *cfserl_create(int type, int instance, bool use_stx)
  33{
  34        struct cfserl *this = kmalloc(sizeof(struct cfserl), GFP_ATOMIC);
  35        if (!this) {
  36                pr_warning("CAIF: %s(): Out of memory\n", __func__);
  37                return NULL;
  38        }
  39        caif_assert(offsetof(struct cfserl, layer) == 0);
  40        memset(this, 0, sizeof(struct cfserl));
  41        this->layer.receive = cfserl_receive;
  42        this->layer.transmit = cfserl_transmit;
  43        this->layer.ctrlcmd = cfserl_ctrlcmd;
  44        this->layer.type = type;
  45        this->usestx = use_stx;
  46        spin_lock_init(&this->sync);
  47        snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "ser1");
  48        return &this->layer;
  49}
  50
  51static int cfserl_receive(struct cflayer *l, struct cfpkt *newpkt)
  52{
  53        struct cfserl *layr = container_obj(l);
  54        u16 pkt_len;
  55        struct cfpkt *pkt = NULL;
  56        struct cfpkt *tail_pkt = NULL;
  57        u8 tmp8;
  58        u16 tmp;
  59        u8 stx = CFSERL_STX;
  60        int ret;
  61        u16 expectlen = 0;
  62
  63        caif_assert(newpkt != NULL);
  64        spin_lock(&layr->sync);
  65
  66        if (layr->incomplete_frm != NULL) {
  67                layr->incomplete_frm =
  68                    cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
  69                pkt = layr->incomplete_frm;
  70                if (pkt == NULL) {
  71                        spin_unlock(&layr->sync);
  72                        return -ENOMEM;
  73                }
  74        } else {
  75                pkt = newpkt;
  76        }
  77        layr->incomplete_frm = NULL;
  78
  79        do {
  80                /* Search for STX at start of pkt if STX is used */
  81                if (layr->usestx) {
  82                        cfpkt_extr_head(pkt, &tmp8, 1);
  83                        if (tmp8 != CFSERL_STX) {
  84                                while (cfpkt_more(pkt)
  85                                       && tmp8 != CFSERL_STX) {
  86                                        cfpkt_extr_head(pkt, &tmp8, 1);
  87                                }
  88                                if (!cfpkt_more(pkt)) {
  89                                        cfpkt_destroy(pkt);
  90                                        layr->incomplete_frm = NULL;
  91                                        spin_unlock(&layr->sync);
  92                                        return -EPROTO;
  93                                }
  94                        }
  95                }
  96
  97                pkt_len = cfpkt_getlen(pkt);
  98
  99                /*
 100                 *  pkt_len is the accumulated length of the packet data
 101                 *  we have received so far.
 102                 *  Exit if frame doesn't hold length.
 103                 */
 104
 105                if (pkt_len < 2) {
 106                        if (layr->usestx)
 107                                cfpkt_add_head(pkt, &stx, 1);
 108                        layr->incomplete_frm = pkt;
 109                        spin_unlock(&layr->sync);
 110                        return 0;
 111                }
 112
 113                /*
 114                 *  Find length of frame.
 115                 *  expectlen is the length we need for a full frame.
 116                 */
 117                cfpkt_peek_head(pkt, &tmp, 2);
 118                expectlen = le16_to_cpu(tmp) + 2;
 119                /*
 120                 * Frame error handling
 121                 */
 122                if (expectlen < CAIF_MINIUM_PACKET_SIZE
 123                    || expectlen > CAIF_MAX_FRAMESIZE) {
 124                        if (!layr->usestx) {
 125                                if (pkt != NULL)
 126                                        cfpkt_destroy(pkt);
 127                                layr->incomplete_frm = NULL;
 128                                expectlen = 0;
 129                                spin_unlock(&layr->sync);
 130                                return -EPROTO;
 131                        }
 132                        continue;
 133                }
 134
 135                if (pkt_len < expectlen) {
 136                        /* Too little received data */
 137                        if (layr->usestx)
 138                                cfpkt_add_head(pkt, &stx, 1);
 139                        layr->incomplete_frm = pkt;
 140                        spin_unlock(&layr->sync);
 141                        return 0;
 142                }
 143
 144                /*
 145                 * Enough data for at least one frame.
 146                 * Split the frame, if too long
 147                 */
 148                if (pkt_len > expectlen)
 149                        tail_pkt = cfpkt_split(pkt, expectlen);
 150                else
 151                        tail_pkt = NULL;
 152
 153                /* Send the first part of packet upwards.*/
 154                spin_unlock(&layr->sync);
 155                ret = layr->layer.up->receive(layr->layer.up, pkt);
 156                spin_lock(&layr->sync);
 157                if (ret == -EILSEQ) {
 158                        if (layr->usestx) {
 159                                if (tail_pkt != NULL)
 160                                        pkt = cfpkt_append(pkt, tail_pkt, 0);
 161                                /* Start search for next STX if frame failed */
 162                                continue;
 163                        } else {
 164                                cfpkt_destroy(pkt);
 165                                pkt = NULL;
 166                        }
 167                }
 168
 169                pkt = tail_pkt;
 170
 171        } while (pkt != NULL);
 172
 173        spin_unlock(&layr->sync);
 174        return 0;
 175}
 176
 177static int cfserl_transmit(struct cflayer *layer, struct cfpkt *newpkt)
 178{
 179        struct cfserl *layr = container_obj(layer);
 180        int ret;
 181        u8 tmp8 = CFSERL_STX;
 182        if (layr->usestx)
 183                cfpkt_add_head(newpkt, &tmp8, 1);
 184        ret = layer->dn->transmit(layer->dn, newpkt);
 185        if (ret < 0)
 186                cfpkt_extr_head(newpkt, &tmp8, 1);
 187
 188        return ret;
 189}
 190
 191static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 192                                int phyid)
 193{
 194        layr->up->ctrlcmd(layr->up, ctrl, phyid);
 195}
 196