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 = kmalloc(sizeof(struct cffrml), GFP_ATOMIC);
  38         if (!this) {
  39                 pr_warn("Out of memory\n");
  40                 return NULL;
  41         }
  42         this->pcpu_refcnt = alloc_percpu(int);
  43         if (this->pcpu_refcnt == NULL) {
  44                 kfree(this);
  45                 return NULL;
  46         }
  47
  48         caif_assert(offsetof(struct cffrml, layer) == 0);
  49
  50         memset(this, 0, sizeof(struct cflayer));
  51         this->layer.receive = cffrml_receive;
  52         this->layer.transmit = cffrml_transmit;
  53         this->layer.ctrlcmd = cffrml_ctrlcmd;
  54         snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "frm%d", phyid);
  55         this->dofcs = use_fcs;
  56         this->layer.id = phyid;
  57         return (struct cflayer *) this;
  58 }
  59
  60 void cffrml_free(struct cflayer *layer)
  61 {
  62         struct cffrml *this = container_obj(layer);
  63         free_percpu(this->pcpu_refcnt);
  64         kfree(layer);
  65 }
  66
  67 void cffrml_set_uplayer(struct cflayer *this, struct cflayer *up)
  68 {
  69         this->up = up;
  70 }
  71
  72 void cffrml_set_dnlayer(struct cflayer *this, struct cflayer *dn)
  73 {
  74         this->dn = dn;
  75 }
  76
  77 static u16 cffrml_checksum(u16 chks, void *buf, u16 len)
  78 {
  79         /* FIXME: FCS should be moved to glue in order to use OS-Specific
  80          * solutions
  81          */
  82         return crc_ccitt(chks, buf, len);
  83 }
  84
  85 static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt)
  86 {
  87         u16 tmp;
  88         u16 len;
  89         u16 hdrchks;
  90         u16 pktchks;
  91         struct cffrml *this;
  92         this = container_obj(layr);
  93
  94         cfpkt_extr_head(pkt, &tmp, 2);
  95         len = le16_to_cpu(tmp);
  96
  97         /* Subtract for FCS on length if FCS is not used. */
  98         if (!this->dofcs)
  99                 len -= 2;
 100
 101         if (cfpkt_setlen(pkt, len) < 0) {
 102                 ++cffrml_rcv_error;
 103                 pr_err("Framing length error (%d)\n", len);
 104                 cfpkt_destroy(pkt);
 105                 return -EPROTO;
 106         }
 107         /*
 108          * Don't do extract if FCS is false, rather do setlen - then we don't
 109          * get a cache-miss.
 110          */
 111         if (this->dofcs) {
 112                 cfpkt_extr_trail(pkt, &tmp, 2);
 113                 hdrchks = le16_to_cpu(tmp);
 114                 pktchks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
 115                 if (pktchks != hdrchks) {
 116                         cfpkt_add_trail(pkt, &tmp, 2);
 117                         ++cffrml_rcv_error;
 118                         ++cffrml_rcv_checsum_error;
 119                         pr_info("Frame checksum error (0x%x != 0x%x)\n",
 120                                 hdrchks, pktchks);
 121                         return -EILSEQ;
 122                 }
 123         }
 124         if (cfpkt_erroneous(pkt)) {
 125                 ++cffrml_rcv_error;
 126                 pr_err("Packet is erroneous!\n");
 127                 cfpkt_destroy(pkt);
 128                 return -EPROTO;
 129         }
 130
 131         if (layr->up == NULL) {
 132                 pr_err("Layr up is missing!\n");
 133                 cfpkt_destroy(pkt);
 134                 return -EINVAL;
 135         }
 136
 137         return layr->up->receive(layr->up, pkt);
 138 }
 139
 140 static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt)
 141 {
 142         int tmp;
 143         u16 chks;
 144         u16 len;
 145         struct cffrml *this = container_obj(layr);
 146         if (this->dofcs) {
 147                 chks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
 148                 tmp = cpu_to_le16(chks);
 149                 cfpkt_add_trail(pkt, &tmp, 2);
 150         } else {
 151                 cfpkt_pad_trail(pkt, 2);
 152         }
 153         len = cfpkt_getlen(pkt);
 154         tmp = cpu_to_le16(len);
 155         cfpkt_add_head(pkt, &tmp, 2);
 156         cfpkt_info(pkt)->hdr_len += 2;
 157         if (cfpkt_erroneous(pkt)) {
 158                 pr_err("Packet is erroneous!\n");
 159                 cfpkt_destroy(pkt);
 160                 return -EPROTO;
 161         }
 162
 163         if (layr->dn == NULL) {
 164                 cfpkt_destroy(pkt);
 165                 return -ENODEV;
 166
 167         }
 168         return layr->dn->transmit(layr->dn, pkt);
 169 }
 170
 171 static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 172                                         int phyid)
 173 {
 174         if (layr->up && layr->up->ctrlcmd)
 175                 layr->up->ctrlcmd(layr->up, ctrl, layr->id);
 176 }
 177
 178 void cffrml_put(struct cflayer *layr)
 179 {
 180         struct cffrml *this = container_obj(layr);
 181         if (layr != NULL && this->pcpu_refcnt != NULL)
 182                 irqsafe_cpu_dec(*this->pcpu_refcnt);
 183 }
 184
 185 void cffrml_hold(struct cflayer *layr)
 186 {
 187         struct cffrml *this = container_obj(layr);
 188         if (layr != NULL && this->pcpu_refcnt != NULL)
 189                 irqsafe_cpu_inc(*this->pcpu_refcnt);
 190 }
 191
 192 int cffrml_refcnt_read(struct cflayer *layr)
 193 {
 194         int i, refcnt = 0;
 195         struct cffrml *this = container_obj(layr);
 196         for_each_possible_cpu(i)
 197                 refcnt += *per_cpu_ptr(this->pcpu_refcnt, i);
 198         return refcnt;
 199 }