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Linux/net/caif/cffrml.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * CAIF Framing Layer.
  4  *
  5  * Copyright (C) ST-Ericsson AB 2010
  6  * Author:      Sjur Brendeland
  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         int 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);
194         for_each_possible_cpu(i)
195                 refcnt += *per_cpu_ptr(this->pcpu_refcnt, i);
196         return refcnt;
197 }
198 

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