Linux Kernel  3.7.1
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cfdgml.c
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1 /*
2  * Copyright (C) ST-Ericsson AB 2010
3  * Author: Sjur Brendeland/[email protected]
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/cfsrvl.h>
14 #include <net/caif/cfpkt.h>
15 
16 
17 #define container_obj(layr) ((struct cfsrvl *) layr)
18 
19 #define DGM_CMD_BIT 0x80
20 #define DGM_FLOW_OFF 0x81
21 #define DGM_FLOW_ON 0x80
22 #define DGM_MTU 1500
23 
24 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
25 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
26 
27 struct cflayer *cfdgml_create(u8 channel_id, struct dev_info *dev_info)
28 {
29  struct cfsrvl *dgm = kzalloc(sizeof(struct cfsrvl), GFP_ATOMIC);
30  if (!dgm)
31  return NULL;
32  caif_assert(offsetof(struct cfsrvl, layer) == 0);
33  cfsrvl_init(dgm, channel_id, dev_info, true);
34  dgm->layer.receive = cfdgml_receive;
35  dgm->layer.transmit = cfdgml_transmit;
36  snprintf(dgm->layer.name, CAIF_LAYER_NAME_SZ - 1, "dgm%d", channel_id);
37  dgm->layer.name[CAIF_LAYER_NAME_SZ - 1] = '\0';
38  return &dgm->layer;
39 }
40 
41 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt)
42 {
43  u8 cmd = -1;
44  u8 dgmhdr[3];
45  int ret;
46  caif_assert(layr->up != NULL);
47  caif_assert(layr->receive != NULL);
48  caif_assert(layr->ctrlcmd != NULL);
49 
50  if (cfpkt_extr_head(pkt, &cmd, 1) < 0) {
51  pr_err("Packet is erroneous!\n");
52  cfpkt_destroy(pkt);
53  return -EPROTO;
54  }
55 
56  if ((cmd & DGM_CMD_BIT) == 0) {
57  if (cfpkt_extr_head(pkt, &dgmhdr, 3) < 0) {
58  pr_err("Packet is erroneous!\n");
59  cfpkt_destroy(pkt);
60  return -EPROTO;
61  }
62  ret = layr->up->receive(layr->up, pkt);
63  return ret;
64  }
65 
66  switch (cmd) {
67  case DGM_FLOW_OFF: /* FLOW OFF */
68  layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_OFF_IND, 0);
69  cfpkt_destroy(pkt);
70  return 0;
71  case DGM_FLOW_ON: /* FLOW ON */
72  layr->ctrlcmd(layr, CAIF_CTRLCMD_FLOW_ON_IND, 0);
73  cfpkt_destroy(pkt);
74  return 0;
75  default:
76  cfpkt_destroy(pkt);
77  pr_info("Unknown datagram control %d (0x%x)\n", cmd, cmd);
78  return -EPROTO;
79  }
80 }
81 
82 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
83 {
85  u32 zero = 0;
86  struct caif_payload_info *info;
87  struct cfsrvl *service = container_obj(layr);
88  int ret;
89 
90  if (!cfsrvl_ready(service, &ret)) {
91  cfpkt_destroy(pkt);
92  return ret;
93  }
94 
95  /* STE Modem cannot handle more than 1500 bytes datagrams */
96  if (cfpkt_getlen(pkt) > DGM_MTU) {
97  cfpkt_destroy(pkt);
98  return -EMSGSIZE;
99  }
100 
101  cfpkt_add_head(pkt, &zero, 3);
102  packet_type = 0x08; /* B9 set - UNCLASSIFIED */
103  cfpkt_add_head(pkt, &packet_type, 1);
104 
105  /* Add info for MUX-layer to route the packet out. */
106  info = cfpkt_info(pkt);
107  info->channel_id = service->layer.id;
108  /* To optimize alignment, we add up the size of CAIF header
109  * before payload.
110  */
111  info->hdr_len = 4;
112  info->dev_info = &service->dev_info;
113  return layr->dn->transmit(layr->dn, pkt);
114 }