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 SERIAL_MINIUM_PACKET_SIZE 4
  18 #define SERIAL_MAX_FRAMESIZE 4096
  19 struct cfserl {
  20         struct cflayer layer;
  21         struct cfpkt *incomplete_frm;
  22         /* Protects parallel processing of incoming packets */
  23         spinlock_t sync;
  24         bool usestx;
  25 };
  26 #define STXLEN(layr) (layr->usestx ? 1 : 0)
  27
  28 static int cfserl_receive(struct cflayer *layr, struct cfpkt *pkt);
  29 static int cfserl_transmit(struct cflayer *layr, struct cfpkt *pkt);
  30 static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
  31                                 int phyid);
  32
  33 struct cflayer *cfserl_create(int type, int instance, bool use_stx)
  34 {
  35         struct cfserl *this = kmalloc(sizeof(struct cfserl), GFP_ATOMIC);
  36         if (!this) {
  37                 pr_warning("CAIF: %s(): Out of memory\n", __func__);
  38                 return NULL;
  39         }
  40         caif_assert(offsetof(struct cfserl, layer) == 0);
  41         memset(this, 0, sizeof(struct cfserl));
  42         this->layer.receive = cfserl_receive;
  43         this->layer.transmit = cfserl_transmit;
  44         this->layer.ctrlcmd = cfserl_ctrlcmd;
  45         this->layer.type = type;
  46         this->usestx = use_stx;
  47         spin_lock_init(&this->sync);
  48         snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "ser1");
  49         return &this->layer;
  50 }
  51
  52 static int cfserl_receive(struct cflayer *l, struct cfpkt *newpkt)
  53 {
  54         struct cfserl *layr = container_obj(l);
  55         u16 pkt_len;
  56         struct cfpkt *pkt = NULL;
  57         struct cfpkt *tail_pkt = NULL;
  58         u8 tmp8;
  59         u16 tmp;
  60         u8 stx = CFSERL_STX;
  61         int ret;
  62         u16 expectlen = 0;
  63
  64         caif_assert(newpkt != NULL);
  65         spin_lock(&layr->sync);
  66
  67         if (layr->incomplete_frm != NULL) {
  68                 layr->incomplete_frm =
  69                     cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
  70                 pkt = layr->incomplete_frm;
  71                 if (pkt == NULL) {
  72                         spin_unlock(&layr->sync);
  73                         return -ENOMEM;
  74                 }
  75         } else {
  76                 pkt = newpkt;
  77         }
  78         layr->incomplete_frm = NULL;
  79
  80         do {
  81                 /* Search for STX at start of pkt if STX is used */
  82                 if (layr->usestx) {
  83                         cfpkt_extr_head(pkt, &tmp8, 1);
  84                         if (tmp8 != CFSERL_STX) {
  85                                 while (cfpkt_more(pkt)
  86                                        && tmp8 != CFSERL_STX) {
  87                                         cfpkt_extr_head(pkt, &tmp8, 1);
  88                                 }
  89                                 if (!cfpkt_more(pkt)) {
  90                                         cfpkt_destroy(pkt);
  91                                         layr->incomplete_frm = NULL;
  92                                         spin_unlock(&layr->sync);
  93                                         return -EPROTO;
  94                                 }
  95                         }
  96                 }
  97
  98                 pkt_len = cfpkt_getlen(pkt);
  99
 100                 /*
 101                  *  pkt_len is the accumulated length of the packet data
 102                  *  we have received so far.
 103                  *  Exit if frame doesn't hold length.
 104                  */
 105
 106                 if (pkt_len < 2) {
 107                         if (layr->usestx)
 108                                 cfpkt_add_head(pkt, &stx, 1);
 109                         layr->incomplete_frm = pkt;
 110                         spin_unlock(&layr->sync);
 111                         return 0;
 112                 }
 113
 114                 /*
 115                  *  Find length of frame.
 116                  *  expectlen is the length we need for a full frame.
 117                  */
 118                 cfpkt_peek_head(pkt, &tmp, 2);
 119                 expectlen = le16_to_cpu(tmp) + 2;
 120                 /*
 121                  * Frame error handling
 122                  */
 123                 if (expectlen < SERIAL_MINIUM_PACKET_SIZE
 124                     || expectlen > SERIAL_MAX_FRAMESIZE) {
 125                         if (!layr->usestx) {
 126                                 if (pkt != NULL)
 127                                         cfpkt_destroy(pkt);
 128                                 layr->incomplete_frm = NULL;
 129                                 expectlen = 0;
 130                                 spin_unlock(&layr->sync);
 131                                 return -EPROTO;
 132                         }
 133                         continue;
 134                 }
 135
 136                 if (pkt_len < expectlen) {
 137                         /* Too little received data */
 138                         if (layr->usestx)
 139                                 cfpkt_add_head(pkt, &stx, 1);
 140                         layr->incomplete_frm = pkt;
 141                         spin_unlock(&layr->sync);
 142                         return 0;
 143                 }
 144
 145                 /*
 146                  * Enough data for at least one frame.
 147                  * Split the frame, if too long
 148                  */
 149                 if (pkt_len > expectlen)
 150                         tail_pkt = cfpkt_split(pkt, expectlen);
 151                 else
 152                         tail_pkt = NULL;
 153
 154                 /* Send the first part of packet upwards.*/
 155                 spin_unlock(&layr->sync);
 156                 ret = layr->layer.up->receive(layr->layer.up, pkt);
 157                 spin_lock(&layr->sync);
 158                 if (ret == -EILSEQ) {
 159                         if (layr->usestx) {
 160                                 if (tail_pkt != NULL)
 161                                         pkt = cfpkt_append(pkt, tail_pkt, 0);
 162                                 /* Start search for next STX if frame failed */
 163                                 continue;
 164                         } else {
 165                                 cfpkt_destroy(pkt);
 166                                 pkt = NULL;
 167                         }
 168                 }
 169
 170                 pkt = tail_pkt;
 171
 172         } while (pkt != NULL);
 173
 174         spin_unlock(&layr->sync);
 175         return 0;
 176 }
 177
 178 static int cfserl_transmit(struct cflayer *layer, struct cfpkt *newpkt)
 179 {
 180         struct cfserl *layr = container_obj(layer);
 181         int ret;
 182         u8 tmp8 = CFSERL_STX;
 183         if (layr->usestx)
 184                 cfpkt_add_head(newpkt, &tmp8, 1);
 185         ret = layer->dn->transmit(layer->dn, newpkt);
 186         if (ret < 0)
 187                 cfpkt_extr_head(newpkt, &tmp8, 1);
 188
 189         return ret;
 190 }
 191
 192 static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 193                                 int phyid)
 194 {
 195         layr->up->ctrlcmd(layr->up, ctrl, phyid);
 196 }