net/caif/cfmuxl.c

   1 /*
   2  * Copyright (C) ST-Ericsson AB 2010
   3  * Author:      Sjur Brendeland/sjur.brandeland@stericsson.com
   4  * License terms: GNU General Public License (GPL) version 2
   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 = kmalloc(sizeof(struct cfmuxl), GFP_ATOMIC);
  51         if (!this)
  52                 return NULL;
  53         memset(this, 0, sizeof(*this));
  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_uplayer(struct cflayer *layr, struct cflayer *up, u8 linkid)
  66 {
  67         struct cfmuxl *muxl = container_obj(layr);
  68
  69         spin_lock_bh(&muxl->receive_lock);
  70         list_add_rcu(&up->node, &muxl->srvl_list);
  71         spin_unlock_bh(&muxl->receive_lock);
  72         return 0;
  73 }
  74
  75 int cfmuxl_set_dnlayer(struct cflayer *layr, struct cflayer *dn, u8 phyid)
  76 {
  77         struct cfmuxl *muxl = (struct cfmuxl *) layr;
  78
  79         spin_lock_bh(&muxl->transmit_lock);
  80         list_add_rcu(&dn->node, &muxl->frml_list);
  81         spin_unlock_bh(&muxl->transmit_lock);
  82         return 0;
  83 }
  84
  85 static struct cflayer *get_from_id(struct list_head *list, u16 id)
  86 {
  87         struct cflayer *lyr;
  88         list_for_each_entry_rcu(lyr, list, node) {
  89                 if (lyr->id == id)
  90                         return lyr;
  91         }
  92
  93         return NULL;
  94 }
  95
  96 struct cflayer *cfmuxl_remove_dnlayer(struct cflayer *layr, u8 phyid)
  97 {
  98         struct cfmuxl *muxl = container_obj(layr);
  99         struct cflayer *dn;
 100         int idx = phyid % DN_CACHE_SIZE;
 101
 102         spin_lock_bh(&muxl->transmit_lock);
 103         rcu_assign_pointer(muxl->dn_cache[idx], NULL);
 104         dn = get_from_id(&muxl->frml_list, phyid);
 105         if (dn == NULL)
 106                 goto out;
 107
 108         list_del_rcu(&dn->node);
 109         caif_assert(dn != NULL);
 110 out:
 111         spin_unlock_bh(&muxl->transmit_lock);
 112         return dn;
 113 }
 114
 115 static struct cflayer *get_up(struct cfmuxl *muxl, u16 id)
 116 {
 117         struct cflayer *up;
 118         int idx = id % UP_CACHE_SIZE;
 119         up = rcu_dereference(muxl->up_cache[idx]);
 120         if (up == NULL || up->id != id) {
 121                 spin_lock_bh(&muxl->receive_lock);
 122                 up = get_from_id(&muxl->srvl_list, id);
 123                 rcu_assign_pointer(muxl->up_cache[idx], up);
 124                 spin_unlock_bh(&muxl->receive_lock);
 125         }
 126         return up;
 127 }
 128
 129 static struct cflayer *get_dn(struct cfmuxl *muxl, struct dev_info *dev_info)
 130 {
 131         struct cflayer *dn;
 132         int idx = dev_info->id % DN_CACHE_SIZE;
 133         dn = rcu_dereference(muxl->dn_cache[idx]);
 134         if (dn == NULL || dn->id != dev_info->id) {
 135                 spin_lock_bh(&muxl->transmit_lock);
 136                 dn = get_from_id(&muxl->frml_list, dev_info->id);
 137                 rcu_assign_pointer(muxl->dn_cache[idx], dn);
 138                 spin_unlock_bh(&muxl->transmit_lock);
 139         }
 140         return dn;
 141 }
 142
 143 struct cflayer *cfmuxl_remove_uplayer(struct cflayer *layr, u8 id)
 144 {
 145         struct cflayer *up;
 146         struct cfmuxl *muxl = container_obj(layr);
 147         int idx = id % UP_CACHE_SIZE;
 148
 149         spin_lock_bh(&muxl->receive_lock);
 150         up = get_from_id(&muxl->srvl_list, id);
 151         if (up == NULL)
 152                 goto out;
 153
 154         rcu_assign_pointer(muxl->up_cache[idx], NULL);
 155         list_del_rcu(&up->node);
 156 out:
 157         spin_unlock_bh(&muxl->receive_lock);
 158         return up;
 159 }
 160
 161 static int cfmuxl_receive(struct cflayer *layr, struct cfpkt *pkt)
 162 {
 163         int ret;
 164         struct cfmuxl *muxl = container_obj(layr);
 165         u8 id;
 166         struct cflayer *up;
 167         if (cfpkt_extr_head(pkt, &id, 1) < 0) {
 168                 pr_err("erroneous Caif Packet\n");
 169                 cfpkt_destroy(pkt);
 170                 return -EPROTO;
 171         }
 172         rcu_read_lock();
 173         up = get_up(muxl, id);
 174
 175         if (up == NULL) {
 176                 pr_debug("Received data on unknown link ID = %d (0x%x)"
 177                         " up == NULL", id, id);
 178                 cfpkt_destroy(pkt);
 179                 /*
 180                  * Don't return ERROR, since modem misbehaves and sends out
 181                  * flow on before linksetup response.
 182                  */
 183
 184                 rcu_read_unlock();
 185                 return /* CFGLU_EPROT; */ 0;
 186         }
 187
 188         /* We can't hold rcu_lock during receive, so take a ref count instead */
 189         cfsrvl_get(up);
 190         rcu_read_unlock();
 191
 192         ret = up->receive(up, pkt);
 193
 194         cfsrvl_put(up);
 195         return ret;
 196 }
 197
 198 static int cfmuxl_transmit(struct cflayer *layr, struct cfpkt *pkt)
 199 {
 200         struct cfmuxl *muxl = container_obj(layr);
 201         int err;
 202         u8 linkid;
 203         struct cflayer *dn;
 204         struct caif_payload_info *info = cfpkt_info(pkt);
 205         BUG_ON(!info);
 206
 207         rcu_read_lock();
 208
 209         dn = get_dn(muxl, info->dev_info);
 210         if (dn == NULL) {
 211                 pr_debug("Send data on unknown phy ID = %d (0x%x)\n",
 212                         info->dev_info->id, info->dev_info->id);
 213                 rcu_read_unlock();
 214                 cfpkt_destroy(pkt);
 215                 return -ENOTCONN;
 216         }
 217
 218         info->hdr_len += 1;
 219         linkid = info->channel_id;
 220         cfpkt_add_head(pkt, &linkid, 1);
 221
 222         /* We can't hold rcu_lock during receive, so take a ref count instead */
 223         cffrml_hold(dn);
 224
 225         rcu_read_unlock();
 226
 227         err = dn->transmit(dn, pkt);
 228
 229         cffrml_put(dn);
 230         return err;
 231 }
 232
 233 static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 234                                 int phyid)
 235 {
 236         struct cfmuxl *muxl = container_obj(layr);
 237         struct cflayer *layer;
 238
 239         rcu_read_lock();
 240         list_for_each_entry_rcu(layer, &muxl->srvl_list, node) {
 241                 if (cfsrvl_phyid_match(layer, phyid) && layer->ctrlcmd)
 242                         /* NOTE: ctrlcmd is not allowed to block */
 243                         layer->ctrlcmd(layer, ctrl, phyid);
 244         }
 245         rcu_read_unlock();
 246 }