net/caif/cffrml.c

   1 /*
   2  * CAIF Framing Layer.
   3  *
   4  * Copyright (C) ST-Ericsson AB 2010
   5  * Author:      Sjur Brendeland/sjur.brandeland@stericsson.com
   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 */
  25         int __percpu            *pcpu_refcnt;
  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                 irqsafe_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                 irqsafe_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);
 194         for_each_possible_cpu(i)
 195                 refcnt += *per_cpu_ptr(this->pcpu_refcnt, i);
 196         return refcnt;
 197 }