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
19struct 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
28static int cfserl_receive(struct cflayer *layr, struct cfpkt *pkt);
29static int cfserl_transmit(struct cflayer *layr, struct cfpkt *pkt);
30static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
31				int phyid);
32
33struct 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
52static 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
178static 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
192static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
193				int phyid)
194{
195	layr->up->ctrlcmd(layr->up, ctrl, phyid);
196}
197