net/caif/cfmuxl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) ST-Ericsson AB 2010
   4  * Author:      Sjur Brendeland
   5  */
   6
   7 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
   8
   9 #include <linux/stddef.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/slab.h>
  12 #include <linux/rculist.h>
  13 #include <net/caif/cfpkt.h>
  14 #include <net/caif/cfmuxl.h>
  15 #include <net/caif/cfsrvl.h>
  16 #include <net/caif/cffrml.h>
  17
  18 #define container_obj(layr) container_of(layr, struct cfmuxl, layer)
  19
  20 #define CAIF_CTRL_CHANNEL 0
  21 #define UP_CACHE_SIZE 8
  22 #define DN_CACHE_SIZE 8
  23
  24 struct cfmuxl {
  25         struct cflayer layer;
  26         struct list_head srvl_list;
  27         struct list_head frml_list;
  28         struct cflayer *up_cache[UP_CACHE_SIZE];
  29         struct cflayer *dn_cache[DN_CACHE_SIZE];
  30         /*
  31          * Set when inserting or removing downwards layers.
  32          */
  33         spinlock_t transmit_lock;
  34
  35         /*
  36          * Set when inserting or removing upwards layers.
  37          */
  38         spinlock_t receive_lock;
  39
  40 };
  41
  42 static int cfmuxl_receive(struct cflayer *layr, struct cfpkt *pkt);
  43 static int cfmuxl_transmit(struct cflayer *layr, struct cfpkt *pkt);
  44 static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
  45                            int phyid);
  46 static struct cflayer *get_up(struct cfmuxl *muxl, u16 id);
  47
  48 struct cflayer *cfmuxl_create(void)
  49 {
  50         struct cfmuxl *this = kzalloc(sizeof(struct cfmuxl), GFP_ATOMIC);
  51
  52         if (!this)
  53                 return NULL;
  54         this->layer.receive = cfmuxl_receive;
  55         this->layer.transmit = cfmuxl_transmit;
  56         this->layer.ctrlcmd = cfmuxl_ctrlcmd;
  57         INIT_LIST_HEAD(&this->srvl_list);
  58         INIT_LIST_HEAD(&this->frml_list);
  59         spin_lock_init(&this->transmit_lock);
  60         spin_lock_init(&this->receive_lock);
  61         snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "mux");
  62         return &this->layer;
  63 }
  64
  65 int cfmuxl_set_dnlayer(struct cflayer *layr, struct cflayer *dn, u8 phyid)
  66 {
  67         struct cfmuxl *muxl = (struct cfmuxl *) layr;
  68
  69         spin_lock_bh(&muxl->transmit_lock);
  70         list_add_rcu(&dn->node, &muxl->frml_list);
  71         spin_unlock_bh(&muxl->transmit_lock);
  72         return 0;
  73 }
  74
  75 static struct cflayer *get_from_id(struct list_head *list, u16 id)
  76 {
  77         struct cflayer *lyr;
  78         list_for_each_entry_rcu(lyr, list, node) {
  79                 if (lyr->id == id)
  80                         return lyr;
  81         }
  82
  83         return NULL;
  84 }
  85
  86 int cfmuxl_set_uplayer(struct cflayer *layr, struct cflayer *up, u8 linkid)
  87 {
  88         struct cfmuxl *muxl = container_obj(layr);
  89         struct cflayer *old;
  90
  91         spin_lock_bh(&muxl->receive_lock);
  92
  93         /* Two entries with same id is wrong, so remove old layer from mux */
  94         old = get_from_id(&muxl->srvl_list, linkid);
  95         if (old != NULL)
  96                 list_del_rcu(&old->node);
  97
  98         list_add_rcu(&up->node, &muxl->srvl_list);
  99         spin_unlock_bh(&muxl->receive_lock);
 100
 101         return 0;
 102 }
 103
 104 struct cflayer *cfmuxl_remove_dnlayer(struct cflayer *layr, u8 phyid)
 105 {
 106         struct cfmuxl *muxl = container_obj(layr);
 107         struct cflayer *dn;
 108         int idx = phyid % DN_CACHE_SIZE;
 109
 110         spin_lock_bh(&muxl->transmit_lock);
 111         RCU_INIT_POINTER(muxl->dn_cache[idx], NULL);
 112         dn = get_from_id(&muxl->frml_list, phyid);
 113         if (dn == NULL)
 114                 goto out;
 115
 116         list_del_rcu(&dn->node);
 117         caif_assert(dn != NULL);
 118 out:
 119         spin_unlock_bh(&muxl->transmit_lock);
 120         return dn;
 121 }
 122
 123 static struct cflayer *get_up(struct cfmuxl *muxl, u16 id)
 124 {
 125         struct cflayer *up;
 126         int idx = id % UP_CACHE_SIZE;
 127         up = rcu_dereference(muxl->up_cache[idx]);
 128         if (up == NULL || up->id != id) {
 129                 spin_lock_bh(&muxl->receive_lock);
 130                 up = get_from_id(&muxl->srvl_list, id);
 131                 rcu_assign_pointer(muxl->up_cache[idx], up);
 132                 spin_unlock_bh(&muxl->receive_lock);
 133         }
 134         return up;
 135 }
 136
 137 static struct cflayer *get_dn(struct cfmuxl *muxl, struct dev_info *dev_info)
 138 {
 139         struct cflayer *dn;
 140         int idx = dev_info->id % DN_CACHE_SIZE;
 141         dn = rcu_dereference(muxl->dn_cache[idx]);
 142         if (dn == NULL || dn->id != dev_info->id) {
 143                 spin_lock_bh(&muxl->transmit_lock);
 144                 dn = get_from_id(&muxl->frml_list, dev_info->id);
 145                 rcu_assign_pointer(muxl->dn_cache[idx], dn);
 146                 spin_unlock_bh(&muxl->transmit_lock);
 147         }
 148         return dn;
 149 }
 150
 151 struct cflayer *cfmuxl_remove_uplayer(struct cflayer *layr, u8 id)
 152 {
 153         struct cflayer *up;
 154         struct cfmuxl *muxl = container_obj(layr);
 155         int idx = id % UP_CACHE_SIZE;
 156
 157         if (id == 0) {
 158                 pr_warn("Trying to remove control layer\n");
 159                 return NULL;
 160         }
 161
 162         spin_lock_bh(&muxl->receive_lock);
 163         up = get_from_id(&muxl->srvl_list, id);
 164         if (up == NULL)
 165                 goto out;
 166
 167         RCU_INIT_POINTER(muxl->up_cache[idx], NULL);
 168         list_del_rcu(&up->node);
 169 out:
 170         spin_unlock_bh(&muxl->receive_lock);
 171         return up;
 172 }
 173
 174 static int cfmuxl_receive(struct cflayer *layr, struct cfpkt *pkt)
 175 {
 176         int ret;
 177         struct cfmuxl *muxl = container_obj(layr);
 178         u8 id;
 179         struct cflayer *up;
 180         if (cfpkt_extr_head(pkt, &id, 1) < 0) {
 181                 pr_err("erroneous Caif Packet\n");
 182                 cfpkt_destroy(pkt);
 183                 return -EPROTO;
 184         }
 185         rcu_read_lock();
 186         up = get_up(muxl, id);
 187
 188         if (up == NULL) {
 189                 pr_debug("Received data on unknown link ID = %d (0x%x)"
 190                         " up == NULL", id, id);
 191                 cfpkt_destroy(pkt);
 192                 /*
 193                  * Don't return ERROR, since modem misbehaves and sends out
 194                  * flow on before linksetup response.
 195                  */
 196
 197                 rcu_read_unlock();
 198                 return /* CFGLU_EPROT; */ 0;
 199         }
 200
 201         /* We can't hold rcu_lock during receive, so take a ref count instead */
 202         cfsrvl_get(up);
 203         rcu_read_unlock();
 204
 205         ret = up->receive(up, pkt);
 206
 207         cfsrvl_put(up);
 208         return ret;
 209 }
 210
 211 static int cfmuxl_transmit(struct cflayer *layr, struct cfpkt *pkt)
 212 {
 213         struct cfmuxl *muxl = container_obj(layr);
 214         int err;
 215         u8 linkid;
 216         struct cflayer *dn;
 217         struct caif_payload_info *info = cfpkt_info(pkt);
 218         BUG_ON(!info);
 219
 220         rcu_read_lock();
 221
 222         dn = get_dn(muxl, info->dev_info);
 223         if (dn == NULL) {
 224                 pr_debug("Send data on unknown phy ID = %d (0x%x)\n",
 225                         info->dev_info->id, info->dev_info->id);
 226                 rcu_read_unlock();
 227                 cfpkt_destroy(pkt);
 228                 return -ENOTCONN;
 229         }
 230
 231         info->hdr_len += 1;
 232         linkid = info->channel_id;
 233         cfpkt_add_head(pkt, &linkid, 1);
 234
 235         /* We can't hold rcu_lock during receive, so take a ref count instead */
 236         cffrml_hold(dn);
 237
 238         rcu_read_unlock();
 239
 240         err = dn->transmit(dn, pkt);
 241
 242         cffrml_put(dn);
 243         return err;
 244 }
 245
 246 static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 247                            int phyid)
 248 {
 249         struct cfmuxl *muxl = container_obj(layr);
 250         struct cflayer *layer;
 251
 252         rcu_read_lock();
 253         list_for_each_entry_rcu(layer, &muxl->srvl_list, node) {
 254
 255                 if (cfsrvl_phyid_match(layer, phyid) && layer->ctrlcmd) {
 256
 257                         if ((ctrl == _CAIF_CTRLCMD_PHYIF_DOWN_IND ||
 258                                 ctrl == CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND) &&
 259                                         layer->id != 0)
 260                                 cfmuxl_remove_uplayer(layr, layer->id);
 261
 262                         /* NOTE: ctrlcmd is not allowed to block */
 263                         layer->ctrlcmd(layer, ctrl, phyid);
 264                 }
 265         }
 266         rcu_read_unlock();
 267 }