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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
  18 struct 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
  27 static int cfserl_receive(struct cflayer *layr, struct cfpkt *pkt);
  28 static int cfserl_transmit(struct cflayer *layr, struct cfpkt *pkt);
  29 static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
  30                                 int phyid);
  31
  32 struct 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
  51 static 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         caif_assert(newpkt != NULL);
  63         spin_lock(&layr->sync);
  64
  65         if (layr->incomplete_frm != NULL) {
  66
  67                 layr->incomplete_frm =
  68                     cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
  69                 pkt = layr->incomplete_frm;
  70         } else {
  71                 pkt = newpkt;
  72         }
  73         layr->incomplete_frm = NULL;
  74
  75         do {
  76                 /* Search for STX at start of pkt if STX is used */
  77                 if (layr->usestx) {
  78                         cfpkt_extr_head(pkt, &tmp8, 1);
  79                         if (tmp8 != CFSERL_STX) {
  80                                 while (cfpkt_more(pkt)
  81                                        && tmp8 != CFSERL_STX) {
  82                                         cfpkt_extr_head(pkt, &tmp8, 1);
  83                                 }
  84                                 if (!cfpkt_more(pkt)) {
  85                                         cfpkt_destroy(pkt);
  86                                         layr->incomplete_frm = NULL;
  87                                         spin_unlock(&layr->sync);
  88                                         return -EPROTO;
  89                                 }
  90                         }
  91                 }
  92
  93                 pkt_len = cfpkt_getlen(pkt);
  94
  95                 /*
  96                  *  pkt_len is the accumulated length of the packet data
  97                  *  we have received so far.
  98                  *  Exit if frame doesn't hold length.
  99                  */
 100
 101                 if (pkt_len < 2) {
 102                         if (layr->usestx)
 103                                 cfpkt_add_head(pkt, &stx, 1);
 104                         layr->incomplete_frm = pkt;
 105                         spin_unlock(&layr->sync);
 106                         return 0;
 107                 }
 108
 109                 /*
 110                  *  Find length of frame.
 111                  *  expectlen is the length we need for a full frame.
 112                  */
 113                 cfpkt_peek_head(pkt, &tmp, 2);
 114                 expectlen = le16_to_cpu(tmp) + 2;
 115                 /*
 116                  * Frame error handling
 117                  */
 118                 if (expectlen < CAIF_MINIUM_PACKET_SIZE
 119                     || expectlen > CAIF_MAX_FRAMESIZE) {
 120                         if (!layr->usestx) {
 121                                 if (pkt != NULL)
 122                                         cfpkt_destroy(pkt);
 123                                 layr->incomplete_frm = NULL;
 124                                 expectlen = 0;
 125                                 spin_unlock(&layr->sync);
 126                                 return -EPROTO;
 127                         }
 128                         continue;
 129                 }
 130
 131                 if (pkt_len < expectlen) {
 132                         /* Too little received data */
 133                         if (layr->usestx)
 134                                 cfpkt_add_head(pkt, &stx, 1);
 135                         layr->incomplete_frm = pkt;
 136                         spin_unlock(&layr->sync);
 137                         return 0;
 138                 }
 139
 140                 /*
 141                  * Enough data for at least one frame.
 142                  * Split the frame, if too long
 143                  */
 144                 if (pkt_len > expectlen)
 145                         tail_pkt = cfpkt_split(pkt, expectlen);
 146                 else
 147                         tail_pkt = NULL;
 148
 149                 /* Send the first part of packet upwards.*/
 150                 spin_unlock(&layr->sync);
 151                 ret = layr->layer.up->receive(layr->layer.up, pkt);
 152                 spin_lock(&layr->sync);
 153                 if (ret == -EILSEQ) {
 154                         if (layr->usestx) {
 155                                 if (tail_pkt != NULL)
 156                                         pkt = cfpkt_append(pkt, tail_pkt, 0);
 157
 158                                 /* Start search for next STX if frame failed */
 159                                 continue;
 160                         } else {
 161                                 cfpkt_destroy(pkt);
 162                                 pkt = NULL;
 163                         }
 164                 }
 165
 166                 pkt = tail_pkt;
 167
 168         } while (pkt != NULL);
 169
 170         spin_unlock(&layr->sync);
 171         return 0;
 172 }
 173
 174 static int cfserl_transmit(struct cflayer *layer, struct cfpkt *newpkt)
 175 {
 176         struct cfserl *layr = container_obj(layer);
 177         int ret;
 178         u8 tmp8 = CFSERL_STX;
 179         if (layr->usestx)
 180                 cfpkt_add_head(newpkt, &tmp8, 1);
 181         ret = layer->dn->transmit(layer->dn, newpkt);
 182         if (ret < 0)
 183                 cfpkt_extr_head(newpkt, &tmp8, 1);
 184
 185         return ret;
 186 }
 187
 188 static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 189                                 int phyid)
 190 {
 191         layr->up->ctrlcmd(layr->up, ctrl, phyid);
 192 }