caif: Use link layer MTU instead of fixed MTU
[linux-2.6.git] / net / caif / cfdgml.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/cfsrvl.h>
12 #include <net/caif/cfpkt.h>
13
14 #define container_obj(layr) ((struct cfsrvl *) layr)
15
16 #define DGM_CMD_BIT  0x80
17 #define DGM_FLOW_OFF 0x81
18 #define DGM_FLOW_ON  0x80
19 #define DGM_CTRL_PKT_SIZE 1
20 #define DGM_MTU 1500
21
22 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
23 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
24
25 struct cflayer *cfdgml_create(u8 channel_id, struct dev_info *dev_info)
26 {
27         struct cfsrvl *dgm = kmalloc(sizeof(struct cfsrvl), GFP_ATOMIC);
28         if (!dgm) {
29                 pr_warning("CAIF: %s(): Out of memory\n", __func__);
30                 return NULL;
31         }
32         caif_assert(offsetof(struct cfsrvl, layer) == 0);
33         memset(dgm, 0, sizeof(struct cfsrvl));
34         cfsrvl_init(dgm, channel_id, dev_info, true);
35         dgm->layer.receive = cfdgml_receive;
36         dgm->layer.transmit = cfdgml_transmit;
37         snprintf(dgm->layer.name, CAIF_LAYER_NAME_SZ - 1, "dgm%d", channel_id);
38         dgm->layer.name[CAIF_LAYER_NAME_SZ - 1] = '\0';
39         return &dgm->layer;
40 }
41
42 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt)
43 {
44         u8 cmd = -1;
45         u8 dgmhdr[3];
46         int ret;
47         caif_assert(layr->up != NULL);
48         caif_assert(layr->receive != NULL);
49         caif_assert(layr->ctrlcmd != NULL);
50
51         if (cfpkt_extr_head(pkt, &cmd, 1) < 0) {
52                 pr_err("CAIF: %s(): Packet is erroneous!\n", __func__);
53                 cfpkt_destroy(pkt);
54                 return -EPROTO;
55         }
56
57         if ((cmd & DGM_CMD_BIT) == 0) {
58                 if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {
59                         pr_err("CAIF: %s(): Packet is erroneous!\n", __func__);
60                         cfpkt_destroy(pkt);
61                         return -EPROTO;
62                 }
63                 ret = layr->up->receive(layr->up, pkt);
64                 return ret;
65         }
66
67         switch (cmd) {
68         case DGM_FLOW_OFF:      /* FLOW OFF */
69                 layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_OFF_IND, 0);
70                 cfpkt_destroy(pkt);
71                 return 0;
72         case DGM_FLOW_ON:       /* FLOW ON */
73                 layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_ON_IND, 0);
74                 cfpkt_destroy(pkt);
75                 return 0;
76         default:
77                 cfpkt_destroy(pkt);
78                 pr_info("CAIF: %s(): Unknown datagram control %d (0x%x)\n",
79                         __func__, cmd, cmd);
80                 return -EPROTO;
81         }
82 }
83
84 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
85 {
86         u32 zero = 0;
87         struct caif_payload_info *info;
88         struct cfsrvl *service = container_obj(layr);
89         int ret;
90         if (!cfsrvl_ready(service, &ret))
91                 return ret;
92
93         /* STE Modem cannot handle more than 1500 bytes datagrams */
94         if (cfpkt_getlen(pkt) > DGM_MTU)
95                 return -EMSGSIZE;
96
97         cfpkt_add_head(pkt, &zero, 4);
98
99         /* Add info for MUX-layer to route the packet out. */
100         info = cfpkt_info(pkt);
101         info->channel_id = service->layer.id;
102         /* To optimize alignment, we add up the size of CAIF header
103          * before payload.
104          */
105         info->hdr_len = 4;
106         info->dev_info = &service->dev_info;
107         ret = layr->dn->transmit(layr->dn, pkt);
108         if (ret < 0) {
109                 u32 tmp32;
110                 cfpkt_extr_head(pkt, &tmp32, 4);
111         }
112         return ret;
113 }