net-caif: add CAIF core protocol stack
[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 #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 CAIF_MINIUM_PACKET_SIZE 4
18 struct cfserl {
19         struct cflayer layer;
20         struct cfpkt *incomplete_frm;
21         /* Protects parallel processing of incoming packets */
22         spinlock_t sync;
23         bool usestx;
24 };
25 #define STXLEN(layr) (layr->usestx ? 1 : 0)
26
27 static int cfserl_receive(struct cflayer *layr, struct cfpkt *pkt);
28 static int cfserl_transmit(struct cflayer *layr, struct cfpkt *pkt);
29 static void cfserl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
30                                 int phyid);
31
32 struct cflayer *cfserl_create(int type, int instance, bool use_stx)
33 {
34         struct cfserl *this = kmalloc(sizeof(struct cfserl), GFP_ATOMIC);
35         if (!this) {
36                 pr_warning("CAIF: %s(): Out of memory\n", __func__);
37                 return NULL;
38         }
39         caif_assert(offsetof(struct cfserl, layer) == 0);
40         memset(this, 0, sizeof(struct cfserl));
41         this->layer.receive = cfserl_receive;
42         this->layer.transmit = cfserl_transmit;
43         this->layer.ctrlcmd = cfserl_ctrlcmd;
44         this->layer.type = type;
45         this->usestx = use_stx;
46         spin_lock_init(&this->sync);
47         snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "ser1");
48         return &this->layer;
49 }
50
51 static int cfserl_receive(struct cflayer *l, struct cfpkt *newpkt)
52 {
53         struct cfserl *layr = container_obj(l);
54         u16 pkt_len;
55         struct cfpkt *pkt = NULL;
56         struct cfpkt *tail_pkt = NULL;
57         u8 tmp8;
58         u16 tmp;
59         u8 stx = CFSERL_STX;
60         int ret;
61         u16 expectlen = 0;
62         caif_assert(newpkt != NULL);
63         spin_lock(&layr->sync);
64
65         if (layr->incomplete_frm != NULL) {
66
67                 layr->incomplete_frm =
68                     cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
69                 pkt = layr->incomplete_frm;
70         } else {
71                 pkt = newpkt;
72         }
73         layr->incomplete_frm = NULL;
74
75         do {
76                 /* Search for STX at start of pkt if STX is used */
77                 if (layr->usestx) {
78                         cfpkt_extr_head(pkt, &tmp8, 1);
79                         if (tmp8 != CFSERL_STX) {
80                                 while (cfpkt_more(pkt)
81                                        && tmp8 != CFSERL_STX) {
82                                         cfpkt_extr_head(pkt, &tmp8, 1);
83                                 }
84                                 if (!cfpkt_more(pkt)) {
85                                         cfpkt_destroy(pkt);
86                                         layr->incomplete_frm = NULL;
87                                         spin_unlock(&layr->sync);
88                                         return -EPROTO;
89                                 }
90                         }
91                 }
92
93                 pkt_len = cfpkt_getlen(pkt);
94
95                 /*
96                  *  pkt_len is the accumulated length of the packet data
97                  *  we have received so far.
98                  *  Exit if frame doesn't hold length.
99                  */
100
101                 if (pkt_len < 2) {
102                         if (layr->usestx)
103                                 cfpkt_add_head(pkt, &stx, 1);
104                         layr->incomplete_frm = pkt;
105                         spin_unlock(&layr->sync);
106                         return 0;
107                 }
108
109                 /*
110                  *  Find length of frame.
111                  *  expectlen is the length we need for a full frame.
112                  */
113                 cfpkt_peek_head(pkt, &tmp, 2);
114                 expectlen = le16_to_cpu(tmp) + 2;
115                 /*
116                  * Frame error handling
117                  */
118                 if (expectlen < CAIF_MINIUM_PACKET_SIZE
119                     || expectlen > CAIF_MAX_FRAMESIZE) {
120                         if (!layr->usestx) {
121                                 if (pkt != NULL)
122                                         cfpkt_destroy(pkt);
123                                 layr->incomplete_frm = NULL;
124                                 expectlen = 0;
125                                 spin_unlock(&layr->sync);
126                                 return -EPROTO;
127                         }
128                         continue;
129                 }
130
131                 if (pkt_len < expectlen) {
132                         /* Too little received data */
133                         if (layr->usestx)
134                                 cfpkt_add_head(pkt, &stx, 1);
135                         layr->incomplete_frm = pkt;
136                         spin_unlock(&layr->sync);
137                         return 0;
138                 }
139
140                 /*
141                  * Enough data for at least one frame.
142                  * Split the frame, if too long
143                  */
144                 if (pkt_len > expectlen)
145                         tail_pkt = cfpkt_split(pkt, expectlen);
146                 else
147                         tail_pkt = NULL;
148
149                 /* Send the first part of packet upwards.*/
150                 spin_unlock(&layr->sync);
151                 ret = layr->layer.up->receive(layr->layer.up, pkt);
152                 spin_lock(&layr->sync);
153                 if (ret == -EILSEQ) {
154                         if (layr->usestx) {
155                                 if (tail_pkt != NULL)
156                                         pkt = cfpkt_append(pkt, tail_pkt, 0);
157
158                                 /* Start search for next STX if frame failed */
159                                 continue;
160                         } else {
161                                 cfpkt_destroy(pkt);
162                                 pkt = NULL;
163                         }
164                 }
165
166                 pkt = tail_pkt;
167
168         } while (pkt != NULL);
169
170         spin_unlock(&layr->sync);
171         return 0;
172 }
173
174 static int cfserl_transmit(struct cflayer *layer, struct cfpkt *newpkt)
175 {
176         struct cfserl *layr = container_obj(layer);
177         int ret;
178         u8 tmp8 = CFSERL_STX;
179         if (layr->usestx)
180                 cfpkt_add_head(newpkt, &tmp8, 1);
181         ret = layer->dn->transmit(layer->dn, newpkt);
182         if (ret < 0)
183                 cfpkt_extr_head(newpkt, &tmp8, 1);
184
185         return ret;
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 }