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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) ST-Ericsson AB 2010
* Author: Sjur Brendeland
*/
#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfpkt.h>
#include <net/caif/cfserl.h>
#define container_obj(layr) ((struct cfserl *) layr)
#define CFSERL_STX 0x02
#define SERIAL_MINIUM_PACKET_SIZE 4
#define SERIAL_MAX_FRAMESIZE 4096
struct cfserl {
struct cflayer layer;
struct cfpkt *incomplete_frm;
/* Protects parallel processing of incoming packets */
spinlock_t sync;
bool usestx;
};
static int cfserl_receive(struct cflayer *layr, struct cfpkt *pkt);
static int cfserl_transmit(struct cflayer *layr, struct cfpkt *pkt);
static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
int phyid);
void cfserl_release(struct cflayer *layer)
{
kfree(layer);
}
struct cflayer *cfserl_create(int instance, bool use_stx)
{
struct cfserl *this = kzalloc(sizeof(struct cfserl), GFP_ATOMIC);
if (!this)
return NULL;
caif_assert(offsetof(struct cfserl, layer) == 0);
this->layer.receive = cfserl_receive;
this->layer.transmit = cfserl_transmit;
this->layer.ctrlcmd = cfserl_ctrlcmd;
this->usestx = use_stx;
spin_lock_init(&this->sync);
snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "ser1");
return &this->layer;
}
static int cfserl_receive(struct cflayer *l, struct cfpkt *newpkt)
{
struct cfserl *layr = container_obj(l);
u16 pkt_len;
struct cfpkt *pkt = NULL;
struct cfpkt *tail_pkt = NULL;
u8 tmp8;
u16 tmp;
u8 stx = CFSERL_STX;
int ret;
u16 expectlen = 0;
caif_assert(newpkt != NULL);
spin_lock(&layr->sync);
if (layr->incomplete_frm != NULL) {
layr->incomplete_frm =
cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
pkt = layr->incomplete_frm;
if (pkt == NULL) {
spin_unlock(&layr->sync);
return -ENOMEM;
}
} else {
pkt = newpkt;
}
layr->incomplete_frm = NULL;
do {
/* Search for STX at start of pkt if STX is used */
if (layr->usestx) {
cfpkt_extr_head(pkt, &tmp8, 1);
if (tmp8 != CFSERL_STX) {
while (cfpkt_more(pkt)
&& tmp8 != CFSERL_STX) {
cfpkt_extr_head(pkt, &tmp8, 1);
}
if (!cfpkt_more(pkt)) {
cfpkt_destroy(pkt);
layr->incomplete_frm = NULL;
spin_unlock(&layr->sync);
return -EPROTO;
}
}
}
pkt_len = cfpkt_getlen(pkt);
/*
* pkt_len is the accumulated length of the packet data
* we have received so far.
* Exit if frame doesn't hold length.
*/
if (pkt_len < 2) {
if (layr->usestx)
cfpkt_add_head(pkt, &stx, 1);
layr->incomplete_frm = pkt;
spin_unlock(&layr->sync);
return 0;
}
/*
* Find length of frame.
* expectlen is the length we need for a full frame.
*/
cfpkt_peek_head(pkt, &tmp, 2);
expectlen = le16_to_cpu(tmp) + 2;
/*
* Frame error handling
*/
if (expectlen < SERIAL_MINIUM_PACKET_SIZE
|| expectlen > SERIAL_MAX_FRAMESIZE) {
if (!layr->usestx) {
if (pkt != NULL)
cfpkt_destroy(pkt);
layr->incomplete_frm = NULL;
spin_unlock(&layr->sync);
return -EPROTO;
}
continue;
}
if (pkt_len < expectlen) {
/* Too little received data */
if (layr->usestx)
cfpkt_add_head(pkt, &stx, 1);
layr->incomplete_frm = pkt;
spin_unlock(&layr->sync);
return 0;
}
/*
* Enough data for at least one frame.
* Split the frame, if too long
*/
if (pkt_len > expectlen)
tail_pkt = cfpkt_split(pkt, expectlen);
else
tail_pkt = NULL;
/* Send the first part of packet upwards.*/
spin_unlock(&layr->sync);
ret = layr->layer.up->receive(layr->layer.up, pkt);
spin_lock(&layr->sync);
if (ret == -EILSEQ) {
if (layr->usestx) {
if (tail_pkt != NULL)
pkt = cfpkt_append(pkt, tail_pkt, 0);
/* Start search for next STX if frame failed */
continue;
} else {
cfpkt_destroy(pkt);
pkt = NULL;
}
}
pkt = tail_pkt;
} while (pkt != NULL);
spin_unlock(&layr->sync);
return 0;
}
static int cfserl_transmit(struct cflayer *layer, struct cfpkt *newpkt)
{
struct cfserl *layr = container_obj(layer);
u8 tmp8 = CFSERL_STX;
if (layr->usestx)
cfpkt_add_head(newpkt, &tmp8, 1);
return layer->dn->transmit(layer->dn, newpkt);
}
static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
int phyid)
{
layr->up->ctrlcmd(layr->up, ctrl, phyid);
}
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