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cffrml.c
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1 /*
2  * CAIF Framing Layer.
3  *
4  * Copyright (C) ST-Ericsson AB 2010
5  * Author: Sjur Brendeland/[email protected]
6  * License terms: GNU General Public License (GPL) version 2
7  */
8 
9 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
10 
11 #include <linux/stddef.h>
12 #include <linux/spinlock.h>
13 #include <linux/slab.h>
14 #include <linux/crc-ccitt.h>
15 #include <linux/netdevice.h>
16 #include <net/caif/caif_layer.h>
17 #include <net/caif/cfpkt.h>
18 #include <net/caif/cffrml.h>
19 
20 #define container_obj(layr) container_of(layr, struct cffrml, layer)
21 
22 struct cffrml {
23  struct cflayer layer;
24  bool dofcs; /* !< FCS active */
26 };
27 
28 static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt);
29 static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt);
30 static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
31  int phyid);
32 
33 static u32 cffrml_rcv_error;
34 static u32 cffrml_rcv_checsum_error;
35 struct cflayer *cffrml_create(u16 phyid, bool use_fcs)
36 {
37  struct cffrml *this = kzalloc(sizeof(struct cffrml), GFP_ATOMIC);
38  if (!this)
39  return NULL;
40  this->pcpu_refcnt = alloc_percpu(int);
41  if (this->pcpu_refcnt == NULL) {
42  kfree(this);
43  return NULL;
44  }
45 
46  caif_assert(offsetof(struct cffrml, layer) == 0);
47 
48  this->layer.receive = cffrml_receive;
49  this->layer.transmit = cffrml_transmit;
50  this->layer.ctrlcmd = cffrml_ctrlcmd;
51  snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "frm%d", phyid);
52  this->dofcs = use_fcs;
53  this->layer.id = phyid;
54  return (struct cflayer *) this;
55 }
56 
57 void cffrml_free(struct cflayer *layer)
58 {
59  struct cffrml *this = container_obj(layer);
60  free_percpu(this->pcpu_refcnt);
61  kfree(layer);
62 }
63 
64 void cffrml_set_uplayer(struct cflayer *this, struct cflayer *up)
65 {
66  this->up = up;
67 }
68 
69 void cffrml_set_dnlayer(struct cflayer *this, struct cflayer *dn)
70 {
71  this->dn = dn;
72 }
73 
74 static u16 cffrml_checksum(u16 chks, void *buf, u16 len)
75 {
76  /* FIXME: FCS should be moved to glue in order to use OS-Specific
77  * solutions
78  */
79  return crc_ccitt(chks, buf, len);
80 }
81 
82 static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt)
83 {
84  u16 tmp;
85  u16 len;
86  u16 hdrchks;
87  u16 pktchks;
88  struct cffrml *this;
89  this = container_obj(layr);
90 
91  cfpkt_extr_head(pkt, &tmp, 2);
92  len = le16_to_cpu(tmp);
93 
94  /* Subtract for FCS on length if FCS is not used. */
95  if (!this->dofcs)
96  len -= 2;
97 
98  if (cfpkt_setlen(pkt, len) < 0) {
99  ++cffrml_rcv_error;
100  pr_err("Framing length error (%d)\n", len);
101  cfpkt_destroy(pkt);
102  return -EPROTO;
103  }
104  /*
105  * Don't do extract if FCS is false, rather do setlen - then we don't
106  * get a cache-miss.
107  */
108  if (this->dofcs) {
109  cfpkt_extr_trail(pkt, &tmp, 2);
110  hdrchks = le16_to_cpu(tmp);
111  pktchks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
112  if (pktchks != hdrchks) {
113  cfpkt_add_trail(pkt, &tmp, 2);
114  ++cffrml_rcv_error;
115  ++cffrml_rcv_checsum_error;
116  pr_info("Frame checksum error (0x%x != 0x%x)\n",
117  hdrchks, pktchks);
118  return -EILSEQ;
119  }
120  }
121  if (cfpkt_erroneous(pkt)) {
122  ++cffrml_rcv_error;
123  pr_err("Packet is erroneous!\n");
124  cfpkt_destroy(pkt);
125  return -EPROTO;
126  }
127 
128  if (layr->up == NULL) {
129  pr_err("Layr up is missing!\n");
130  cfpkt_destroy(pkt);
131  return -EINVAL;
132  }
133 
134  return layr->up->receive(layr->up, pkt);
135 }
136 
137 static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt)
138 {
139  u16 chks;
140  u16 len;
141  __le16 data;
142 
143  struct cffrml *this = container_obj(layr);
144  if (this->dofcs) {
145  chks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
146  data = cpu_to_le16(chks);
147  cfpkt_add_trail(pkt, &data, 2);
148  } else {
149  cfpkt_pad_trail(pkt, 2);
150  }
151  len = cfpkt_getlen(pkt);
152  data = cpu_to_le16(len);
153  cfpkt_add_head(pkt, &data, 2);
154  cfpkt_info(pkt)->hdr_len += 2;
155  if (cfpkt_erroneous(pkt)) {
156  pr_err("Packet is erroneous!\n");
157  cfpkt_destroy(pkt);
158  return -EPROTO;
159  }
160 
161  if (layr->dn == NULL) {
162  cfpkt_destroy(pkt);
163  return -ENODEV;
164 
165  }
166  return layr->dn->transmit(layr->dn, pkt);
167 }
168 
169 static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
170  int phyid)
171 {
172  if (layr->up && layr->up->ctrlcmd)
173  layr->up->ctrlcmd(layr->up, ctrl, layr->id);
174 }
175 
176 void cffrml_put(struct cflayer *layr)
177 {
178  struct cffrml *this = container_obj(layr);
179  if (layr != NULL && this->pcpu_refcnt != NULL)
180  this_cpu_dec(*this->pcpu_refcnt);
181 }
182 
183 void cffrml_hold(struct cflayer *layr)
184 {
185  struct cffrml *this = container_obj(layr);
186  if (layr != NULL && this->pcpu_refcnt != NULL)
187  this_cpu_inc(*this->pcpu_refcnt);
188 }
189 
190 int cffrml_refcnt_read(struct cflayer *layr)
191 {
192  int i, refcnt = 0;
193  struct cffrml *this = container_obj(layr);
195  refcnt += *per_cpu_ptr(this->pcpu_refcnt, i);
196  return refcnt;
197 }