[linux.git] / net / caif / cfserl.c

/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland
 * License terms: GNU General Public License (GPL) version 2
 */

#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);

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;
				expectlen = 0;
				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);
}
Commit	Line	Data
b482cd20 SB	1	/*
b482cd20 SB	2	* Copyright (C) ST-Ericsson AB 2010
26ee65e6	3	* Author: Sjur Brendeland
b482cd20 SB	4	* License terms: GNU General Public License (GPL) version 2
	5	*/
	6
b31fa5ba JP	7	#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
b31fa5ba JP	8
b482cd20 SB	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
2aa40aef SB	19	#define SERIAL_MINIUM_PACKET_SIZE 4
2aa40aef SB	20	#define SERIAL_MAX_FRAMESIZE 4096
b482cd20 SB	21	struct 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	};
b482cd20 SB	28
	29	static int cfserl_receive(struct cflayer layr, struct cfpkt pkt);
	30	static int cfserl_transmit(struct cflayer layr, struct cfpkt pkt);
	31	static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
3bffc475	32	int phyid);
b482cd20	33
e977b4cf	34	struct cflayer *cfserl_create(int instance, bool use_stx)
b482cd20	35	{
7ac2ed0c JP	36	struct cfserl *this = kzalloc(sizeof(struct cfserl), GFP_ATOMIC);
7ac2ed0c JP	37	if (!this)
b482cd20	38	return NULL;
b482cd20	39	caif_assert(offsetof(struct cfserl, layer) == 0);
b482cd20 SB	40	this->layer.receive = cfserl_receive;
	41	this->layer.transmit = cfserl_transmit;
	42	this->layer.ctrlcmd = cfserl_ctrlcmd;
b482cd20 SB	43	this->usestx = use_stx;
	44	spin_lock_init(&this->sync);
	45	snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "ser1");
	46	return &this->layer;
	47	}
	48
	49	static int cfserl_receive(struct cflayer l, struct cfpkt newpkt)
	50	{
	51	struct cfserl *layr = container_obj(l);
	52	u16 pkt_len;
	53	struct cfpkt *pkt = NULL;
	54	struct cfpkt *tail_pkt = NULL;
	55	u8 tmp8;
	56	u16 tmp;
	57	u8 stx = CFSERL_STX;
	58	int ret;
	59	u16 expectlen = 0;
97dc875f	60
b482cd20 SB	61	caif_assert(newpkt != NULL);
	62	spin_lock(&layr->sync);
	63
	64	if (layr->incomplete_frm != NULL) {
b482cd20 SB	65	layr->incomplete_frm =
	66	cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
	67	pkt = layr->incomplete_frm;
97dc875f DC	68	if (pkt == NULL) {
97dc875f DC	69	spin_unlock(&layr->sync);
638e628a	70	return -ENOMEM;
97dc875f	71	}
b482cd20 SB	72	} else {
	73	pkt = newpkt;
	74	}
	75	layr->incomplete_frm = NULL;
	76
	77	do {
	78	/* Search for STX at start of pkt if STX is used */
	79	if (layr->usestx) {
	80	cfpkt_extr_head(pkt, &tmp8, 1);
	81	if (tmp8 != CFSERL_STX) {
	82	while (cfpkt_more(pkt)
	83	&& tmp8 != CFSERL_STX) {
	84	cfpkt_extr_head(pkt, &tmp8, 1);
	85	}
	86	if (!cfpkt_more(pkt)) {
	87	cfpkt_destroy(pkt);
	88	layr->incomplete_frm = NULL;
	89	spin_unlock(&layr->sync);
	90	return -EPROTO;
	91	}
	92	}
	93	}
	94
	95	pkt_len = cfpkt_getlen(pkt);
	96
	97	/*
	98	* pkt_len is the accumulated length of the packet data
	99	* we have received so far.
	100	* Exit if frame doesn't hold length.
	101	*/
	102
	103	if (pkt_len < 2) {
	104	if (layr->usestx)
	105	cfpkt_add_head(pkt, &stx, 1);
	106	layr->incomplete_frm = pkt;
	107	spin_unlock(&layr->sync);
	108	return 0;
	109	}
	110
	111	/*
	112	* Find length of frame.
	113	* expectlen is the length we need for a full frame.
	114	*/
	115	cfpkt_peek_head(pkt, &tmp, 2);
	116	expectlen = le16_to_cpu(tmp) + 2;
	117	/*
	118	* Frame error handling
	119	*/
2aa40aef SB	120	if (expectlen < SERIAL_MINIUM_PACKET_SIZE
2aa40aef SB	121	\|\| expectlen > SERIAL_MAX_FRAMESIZE) {
b482cd20 SB	122	if (!layr->usestx) {
	123	if (pkt != NULL)
	124	cfpkt_destroy(pkt);
	125	layr->incomplete_frm = NULL;
	126	expectlen = 0;
	127	spin_unlock(&layr->sync);
	128	return -EPROTO;
	129	}
	130	continue;
	131	}
	132
	133	if (pkt_len < expectlen) {
	134	/* Too little received data */
	135	if (layr->usestx)
	136	cfpkt_add_head(pkt, &stx, 1);
	137	layr->incomplete_frm = pkt;
	138	spin_unlock(&layr->sync);
	139	return 0;
	140	}
	141
	142	/*
	143	* Enough data for at least one frame.
	144	* Split the frame, if too long
	145	*/
	146	if (pkt_len > expectlen)
	147	tail_pkt = cfpkt_split(pkt, expectlen);
	148	else
	149	tail_pkt = NULL;
	150
	151	/* Send the first part of packet upwards.*/
	152	spin_unlock(&layr->sync);
	153	ret = layr->layer.up->receive(layr->layer.up, pkt);
	154	spin_lock(&layr->sync);
	155	if (ret == -EILSEQ) {
	156	if (layr->usestx) {
	157	if (tail_pkt != NULL)
	158	pkt = cfpkt_append(pkt, tail_pkt, 0);
b482cd20 SB	159	/* Start search for next STX if frame failed */
	160	continue;
	161	} else {
	162	cfpkt_destroy(pkt);
	163	pkt = NULL;
	164	}
	165	}
	166
	167	pkt = tail_pkt;
	168
	169	} while (pkt != NULL);
	170
	171	spin_unlock(&layr->sync);
	172	return 0;
	173	}
	174
	175	static int cfserl_transmit(struct cflayer layer, struct cfpkt newpkt)
	176	{
	177	struct cfserl *layr = container_obj(layer);
b482cd20 SB	178	u8 tmp8 = CFSERL_STX;
	179	if (layr->usestx)
	180	cfpkt_add_head(newpkt, &tmp8, 1);
4dd820c0	181	return layer->dn->transmit(layer->dn, newpkt);
b482cd20 SB	182	}
	183
	184	static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
3bffc475	185	int phyid)
b482cd20 SB	186	{
	187	layr->up->ctrlcmd(layr->up, ctrl, phyid);
	188	}