aboutsummaryrefslogtreecommitdiffstats
path: root/net/caif/cfserl.c
blob: 9297f7dea9d8c164d4d5652d7930866154556350 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland/sjur.brandeland@stericsson.com
 * 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;
};
#define STXLEN(layr) (layr->usestx ? 1 : 0)

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 type, int instance, bool use_stx)
{
	struct cfserl *this = kmalloc(sizeof(struct cfserl), GFP_ATOMIC);
	if (!this) {
		pr_warn("Out of memory\n");
		return NULL;
	}
	caif_assert(offsetof(struct cfserl, layer) == 0);
	memset(this, 0, sizeof(struct cfserl));
	this->layer.receive = cfserl_receive;
	this->layer.transmit = cfserl_transmit;
	this->layer.ctrlcmd = cfserl_ctrlcmd;
	this->layer.type = type;
	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);
	int ret;
	u8 tmp8 = CFSERL_STX;
	if (layr->usestx)
		cfpkt_add_head(newpkt, &tmp8, 1);
	ret = layer->dn->transmit(layer->dn, newpkt);
	if (ret < 0)
		cfpkt_extr_head(newpkt, &tmp8, 1);

	return ret;
}

static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
				int phyid)
{
	layr->up->ctrlcmd(layr->up, ctrl, phyid);
}

Privacy Policy