net: introduce DST_NOPEER dst flag
[linux-2.6.git] / net / caif / cfserl.c
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 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
8
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
19 #define SERIAL_MINIUM_PACKET_SIZE 4
20 #define SERIAL_MAX_FRAMESIZE 4096
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 };
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,
32                                 int phyid);
33
34 struct cflayer *cfserl_create(int type, int instance, bool use_stx)
35 {
36         struct cfserl *this = kmalloc(sizeof(struct cfserl), GFP_ATOMIC);
37         if (!this) {
38                 pr_warn("Out of memory\n");
39                 return NULL;
40         }
41         caif_assert(offsetof(struct cfserl, layer) == 0);
42         memset(this, 0, sizeof(struct cfserl));
43         this->layer.receive = cfserl_receive;
44         this->layer.transmit = cfserl_transmit;
45         this->layer.ctrlcmd = cfserl_ctrlcmd;
46         this->layer.type = type;
47         this->usestx = use_stx;
48         spin_lock_init(&this->sync);
49         snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "ser1");
50         return &this->layer;
51 }
52
53 static int cfserl_receive(struct cflayer *l, struct cfpkt *newpkt)
54 {
55         struct cfserl *layr = container_obj(l);
56         u16 pkt_len;
57         struct cfpkt *pkt = NULL;
58         struct cfpkt *tail_pkt = NULL;
59         u8 tmp8;
60         u16 tmp;
61         u8 stx = CFSERL_STX;
62         int ret;
63         u16 expectlen = 0;
64
65         caif_assert(newpkt != NULL);
66         spin_lock(&layr->sync);
67
68         if (layr->incomplete_frm != NULL) {
69                 layr->incomplete_frm =
70                     cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
71                 pkt = layr->incomplete_frm;
72                 if (pkt == NULL) {
73                         spin_unlock(&layr->sync);
74                         return -ENOMEM;
75                 }
76         } else {
77                 pkt = newpkt;
78         }
79         layr->incomplete_frm = NULL;
80
81         do {
82                 /* Search for STX at start of pkt if STX is used */
83                 if (layr->usestx) {
84                         cfpkt_extr_head(pkt, &tmp8, 1);
85                         if (tmp8 != CFSERL_STX) {
86                                 while (cfpkt_more(pkt)
87                                        && tmp8 != CFSERL_STX) {
88                                         cfpkt_extr_head(pkt, &tmp8, 1);
89                                 }
90                                 if (!cfpkt_more(pkt)) {
91                                         cfpkt_destroy(pkt);
92                                         layr->incomplete_frm = NULL;
93                                         spin_unlock(&layr->sync);
94                                         return -EPROTO;
95                                 }
96                         }
97                 }
98
99                 pkt_len = cfpkt_getlen(pkt);
100
101                 /*
102                  *  pkt_len is the accumulated length of the packet data
103                  *  we have received so far.
104                  *  Exit if frame doesn't hold length.
105                  */
106
107                 if (pkt_len < 2) {
108                         if (layr->usestx)
109                                 cfpkt_add_head(pkt, &stx, 1);
110                         layr->incomplete_frm = pkt;
111                         spin_unlock(&layr->sync);
112                         return 0;
113                 }
114
115                 /*
116                  *  Find length of frame.
117                  *  expectlen is the length we need for a full frame.
118                  */
119                 cfpkt_peek_head(pkt, &tmp, 2);
120                 expectlen = le16_to_cpu(tmp) + 2;
121                 /*
122                  * Frame error handling
123                  */
124                 if (expectlen < SERIAL_MINIUM_PACKET_SIZE
125                     || expectlen > SERIAL_MAX_FRAMESIZE) {
126                         if (!layr->usestx) {
127                                 if (pkt != NULL)
128                                         cfpkt_destroy(pkt);
129                                 layr->incomplete_frm = NULL;
130                                 expectlen = 0;
131                                 spin_unlock(&layr->sync);
132                                 return -EPROTO;
133                         }
134                         continue;
135                 }
136
137                 if (pkt_len < expectlen) {
138                         /* Too little received data */
139                         if (layr->usestx)
140                                 cfpkt_add_head(pkt, &stx, 1);
141                         layr->incomplete_frm = pkt;
142                         spin_unlock(&layr->sync);
143                         return 0;
144                 }
145
146                 /*
147                  * Enough data for at least one frame.
148                  * Split the frame, if too long
149                  */
150                 if (pkt_len > expectlen)
151                         tail_pkt = cfpkt_split(pkt, expectlen);
152                 else
153                         tail_pkt = NULL;
154
155                 /* Send the first part of packet upwards.*/
156                 spin_unlock(&layr->sync);
157                 ret = layr->layer.up->receive(layr->layer.up, pkt);
158                 spin_lock(&layr->sync);
159                 if (ret == -EILSEQ) {
160                         if (layr->usestx) {
161                                 if (tail_pkt != NULL)
162                                         pkt = cfpkt_append(pkt, tail_pkt, 0);
163                                 /* Start search for next STX if frame failed */
164                                 continue;
165                         } else {
166                                 cfpkt_destroy(pkt);
167                                 pkt = NULL;
168                         }
169                 }
170
171                 pkt = tail_pkt;
172
173         } while (pkt != NULL);
174
175         spin_unlock(&layr->sync);
176         return 0;
177 }
178
179 static int cfserl_transmit(struct cflayer *layer, struct cfpkt *newpkt)
180 {
181         struct cfserl *layr = container_obj(layer);
182         u8 tmp8 = CFSERL_STX;
183         if (layr->usestx)
184                 cfpkt_add_head(newpkt, &tmp8, 1);
185         return layer->dn->transmit(layer->dn, newpkt);
186 }
187
188 static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
189                                 int phyid)
190 {
191         layr->up->ctrlcmd(layr->up, ctrl, phyid);
192 }