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Linux/net/caif/cffrml.c

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  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 }
200 

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