LXR linux/net/caif/cfserl.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) ST-Ericsson AB 2010
   4 * Author:      Sjur Brendeland
   5 */
   6
   7#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
   8
   9#include <linux/stddef.h>
  10#include <linux/spinlock.h>
  11#include <linux/slab.h>
  12#include <net/caif/caif_layer.h>
  13#include <net/caif/cfpkt.h>
  14#include <net/caif/cfserl.h>
  15
  16#define container_obj(layr) ((struct cfserl *) layr)
  17
  18#define CFSERL_STX 0x02
  19#define SERIAL_MINIUM_PACKET_SIZE 4
  20#define SERIAL_MAX_FRAMESIZE 4096
  21struct cfserl {
  22        struct cflayer layer;
  23        struct cfpkt *incomplete_frm;
  24        /* Protects parallel processing of incoming packets */
  25        spinlock_t sync;
  26        bool usestx;
  27};
  28
  29static int cfserl_receive(struct cflayer *layr, struct cfpkt *pkt);
  30static int cfserl_transmit(struct cflayer *layr, struct cfpkt *pkt);
  31static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
  32                           int phyid);
  33
  34void cfserl_release(struct cflayer *layer)
  35{
  36        kfree(layer);
  37}
  38
  39struct cflayer *cfserl_create(int instance, bool use_stx)
  40{
  41        struct cfserl *this = kzalloc(sizeof(struct cfserl), GFP_ATOMIC);
  42        if (!this)
  43                return NULL;
  44        caif_assert(offsetof(struct cfserl, layer) == 0);
  45        this->layer.receive = cfserl_receive;
  46        this->layer.transmit = cfserl_transmit;
  47        this->layer.ctrlcmd = cfserl_ctrlcmd;
  48        this->usestx = use_stx;
  49        spin_lock_init(&this->sync);
  50        snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "ser1");
  51        return &this->layer;
  52}
  53
  54static int cfserl_receive(struct cflayer *l, struct cfpkt *newpkt)
  55{
  56        struct cfserl *layr = container_obj(l);
  57        u16 pkt_len;
  58        struct cfpkt *pkt = NULL;
  59        struct cfpkt *tail_pkt = NULL;
  60        u8 tmp8;
  61        u16 tmp;
  62        u8 stx = CFSERL_STX;
  63        int ret;
  64        u16 expectlen = 0;
  65
  66        caif_assert(newpkt != NULL);
  67        spin_lock(&layr->sync);
  68
  69        if (layr->incomplete_frm != NULL) {
  70                layr->incomplete_frm =
  71                    cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
  72                pkt = layr->incomplete_frm;
  73                if (pkt == NULL) {
  74                        spin_unlock(&layr->sync);
  75                        return -ENOMEM;
  76                }
  77        } else {
  78                pkt = newpkt;
  79        }
  80        layr->incomplete_frm = NULL;
  81
  82        do {
  83                /* Search for STX at start of pkt if STX is used */
  84                if (layr->usestx) {
  85                        cfpkt_extr_head(pkt, &tmp8, 1);
  86                        if (tmp8 != CFSERL_STX) {
  87                                while (cfpkt_more(pkt)
  88                                       && tmp8 != CFSERL_STX) {
  89                                        cfpkt_extr_head(pkt, &tmp8, 1);
  90                                }
  91                                if (!cfpkt_more(pkt)) {
  92                                        cfpkt_destroy(pkt);
  93                                        layr->incomplete_frm = NULL;
  94                                        spin_unlock(&layr->sync);
  95                                        return -EPROTO;
  96                                }
  97                        }
  98                }
  99
 100                pkt_len = cfpkt_getlen(pkt);
 101
 102                /*
 103                 *  pkt_len is the accumulated length of the packet data
 104                 *  we have received so far.
 105                 *  Exit if frame doesn't hold length.
 106                 */
 107
 108                if (pkt_len < 2) {
 109                        if (layr->usestx)
 110                                cfpkt_add_head(pkt, &stx, 1);
 111                        layr->incomplete_frm = pkt;
 112                        spin_unlock(&layr->sync);
 113                        return 0;
 114                }
 115
 116                /*
 117                 *  Find length of frame.
 118                 *  expectlen is the length we need for a full frame.
 119                 */
 120                cfpkt_peek_head(pkt, &tmp, 2);
 121                expectlen = le16_to_cpu(tmp) + 2;
 122                /*
 123                 * Frame error handling
 124                 */
 125                if (expectlen < SERIAL_MINIUM_PACKET_SIZE
 126                    || expectlen > SERIAL_MAX_FRAMESIZE) {
 127                        if (!layr->usestx) {
 128                                if (pkt != NULL)
 129                                        cfpkt_destroy(pkt);
 130                                layr->incomplete_frm = NULL;
 131                                expectlen = 0;
 132                                spin_unlock(&layr->sync);
 133                                return -EPROTO;
 134                        }
 135                        continue;
 136                }
 137
 138                if (pkt_len < expectlen) {
 139                        /* Too little received data */
 140                        if (layr->usestx)
 141                                cfpkt_add_head(pkt, &stx, 1);
 142                        layr->incomplete_frm = pkt;
 143                        spin_unlock(&layr->sync);
 144                        return 0;
 145                }
 146
 147                /*
 148                 * Enough data for at least one frame.
 149                 * Split the frame, if too long
 150                 */
 151                if (pkt_len > expectlen)
 152                        tail_pkt = cfpkt_split(pkt, expectlen);
 153                else
 154                        tail_pkt = NULL;
 155
 156                /* Send the first part of packet upwards.*/
 157                spin_unlock(&layr->sync);
 158                ret = layr->layer.up->receive(layr->layer.up, pkt);
 159                spin_lock(&layr->sync);
 160                if (ret == -EILSEQ) {
 161                        if (layr->usestx) {
 162                                if (tail_pkt != NULL)
 163                                        pkt = cfpkt_append(pkt, tail_pkt, 0);
 164                                /* Start search for next STX if frame failed */
 165                                continue;
 166                        } else {
 167                                cfpkt_destroy(pkt);
 168                                pkt = NULL;
 169                        }
 170                }
 171
 172                pkt = tail_pkt;
 173
 174        } while (pkt != NULL);
 175
 176        spin_unlock(&layr->sync);
 177        return 0;
 178}
 179
 180static int cfserl_transmit(struct cflayer *layer, struct cfpkt *newpkt)
 181{
 182        struct cfserl *layr = container_obj(layer);
 183        u8 tmp8 = CFSERL_STX;
 184        if (layr->usestx)
 185                cfpkt_add_head(newpkt, &tmp8, 1);
 186        return layer->dn->transmit(layer->dn, newpkt);
 187}
 188
 189static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 190                           int phyid)
 191{
 192        layr->up->ctrlcmd(layr->up, ctrl, phyid);
 193}
 194