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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/net/caif/cfdgml.c
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// SPDX-License-Identifier: GPL-2.0-only

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/*

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 * Copyright (C) ST-Ericsson AB 2010

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 * Author:	Sjur Brendeland

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 */

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#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__

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#include <linux/stddef.h>

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#include <linux/spinlock.h>

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#include <linux/slab.h>

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#include <net/caif/caif_layer.h>

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#include <net/caif/cfsrvl.h>

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#include <net/caif/cfpkt.h>

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#define container_obj(layr) ((struct cfsrvl *) layr)

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#define DGM_CMD_BIT  0x80

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#define DGM_FLOW_OFF 0x81

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#define DGM_FLOW_ON  0x80

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#define DGM_MTU 1500

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static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);

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static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);

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struct cflayer *cfdgml_create(u8 channel_id, struct dev_info *dev_info)

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{

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	struct cfsrvl *dgm = kzalloc(sizeof(struct cfsrvl), GFP_ATOMIC);

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	if (!dgm)

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		return NULL;

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	caif_assert(offsetof(struct cfsrvl, layer) == 0);

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	cfsrvl_init(dgm, channel_id, dev_info, true);

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	dgm->layer.receive = cfdgml_receive;

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	dgm->layer.transmit = cfdgml_transmit;

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	snprintf(dgm->layer.name, CAIF_LAYER_NAME_SZ, "dgm%d", channel_id);

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	return &dgm->layer;

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}

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static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt)

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{

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	u8 cmd = -1;

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	u8 dgmhdr[3];

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	int ret;

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	caif_assert(layr->up != NULL);

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	caif_assert(layr->receive != NULL);

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	caif_assert(layr->ctrlcmd != NULL);

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	if (cfpkt_extr_head(pkt, &cmd, 1) < 0) {

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		pr_err("Packet is erroneous!\n");

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		cfpkt_destroy(pkt);

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		return -EPROTO;

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	}

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	if ((cmd & DGM_CMD_BIT) == 0) {

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		if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {

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			pr_err("Packet is erroneous!\n");

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			cfpkt_destroy(pkt);

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			return -EPROTO;

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		}

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		ret = layr->up->receive(layr->up, pkt);

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		return ret;

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	}

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	switch (cmd) {

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	case DGM_FLOW_OFF:	/* FLOW OFF */

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		layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_OFF_IND, 0);

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		cfpkt_destroy(pkt);

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		return 0;

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	case DGM_FLOW_ON:	/* FLOW ON */

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		layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_ON_IND, 0);

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		cfpkt_destroy(pkt);

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		return 0;

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	default:

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		cfpkt_destroy(pkt);

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		pr_info("Unknown datagram control %d (0x%x)\n", cmd, cmd);

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		return -EPROTO;

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	}

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}

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static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)

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{

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	u8 packet_type;

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	u32 zero = 0;

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	struct caif_payload_info *info;

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	struct cfsrvl *service = container_obj(layr);

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	int ret;

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	if (!cfsrvl_ready(service, &ret)) {

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		cfpkt_destroy(pkt);

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		return ret;

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	}

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	/* STE Modem cannot handle more than 1500 bytes datagrams */

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	if (cfpkt_getlen(pkt) > DGM_MTU) {

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		cfpkt_destroy(pkt);

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		return -EMSGSIZE;

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	}

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	cfpkt_add_head(pkt, &zero, 3);

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	packet_type = 0x08; /* B9 set - UNCLASSIFIED */

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	cfpkt_add_head(pkt, &packet_type, 1);

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	/* Add info for MUX-layer to route the packet out. */

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	info = cfpkt_info(pkt);

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	info->channel_id = service->layer.id;

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	/* To optimize alignment, we add up the size of CAIF header

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	 * before payload.

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	 */

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	info->hdr_len = 4;

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	info->dev_info = &service->dev_info;

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	return layr->dn->transmit(layr->dn, pkt);

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}

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