net/caif/cfserl.c

   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
  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
 177 static 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
 191 static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 192                                 int phyid)
 193 {
 194         layr->up->ctrlcmd(layr->up, ctrl, phyid);
 195 }