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;
cffrml_create(u16 phyid,bool use_fcs)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 
cffrml_free(struct cflayer * layer)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 
cffrml_set_uplayer(struct cflayer * this,struct cflayer * up)64 void cffrml_set_uplayer(struct cflayer *this, struct cflayer *up)
65 {
66 	this->up = up;
67 }
68 
cffrml_set_dnlayer(struct cflayer * this,struct cflayer * dn)69 void cffrml_set_dnlayer(struct cflayer *this, struct cflayer *dn)
70 {
71 	this->dn = dn;
72 }
73 
cffrml_checksum(u16 chks,void * buf,u16 len)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 
cffrml_receive(struct cflayer * layr,struct cfpkt * pkt)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 
cffrml_transmit(struct cflayer * layr,struct cfpkt * pkt)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 
cffrml_ctrlcmd(struct cflayer * layr,enum caif_ctrlcmd ctrl,int phyid)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 
cffrml_put(struct cflayer * layr)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 
cffrml_hold(struct cflayer * layr)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 
cffrml_refcnt_read(struct cflayer * layr)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