seq_ports.c

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/*
 *   ALSA sequencer Ports
 *   Copyright (c) 1998 by Frank van de Pol <[email protected]>
 *                         Jaroslav Kysela <[email protected]>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <sound/core.h>
#include <linux/slab.h>
#include <linux/module.h>
#include "seq_system.h"
#include "seq_ports.h"
#include "seq_clientmgr.h"

/*

   registration of client ports

 */


/* 

NOTE: the current implementation of the port structure as a linked list is
not optimal for clients that have many ports. For sending messages to all
subscribers of a port we first need to find the address of the port
structure, which means we have to traverse the list. A direct access table
(array) would be better, but big preallocated arrays waste memory.

Possible actions:

1) leave it this way, a client does normaly does not have more than a few
ports

2) replace the linked list of ports by a array of pointers which is
dynamicly kmalloced. When a port is added or deleted we can simply allocate
a new array, copy the corresponding pointers, and delete the old one. We
then only need a pointer to this array, and an integer that tells us how
much elements are in array.

*/

/* return pointer to port structure - port is locked if found */
struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
                         int num)
{
    struct snd_seq_client_port *port;

    if (client == NULL)
        return NULL;
    read_lock(&client->ports_lock);
    list_for_each_entry(port, &client->ports_list_head, list) {
        if (port->addr.port == num) {
            if (port->closing)
                break; /* deleting now */
            snd_use_lock_use(&port->use_lock);
            read_unlock(&client->ports_lock);
            return port;
        }
    }
    read_unlock(&client->ports_lock);
    return NULL;        /* not found */
}


/* search for the next port - port is locked if found */
struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
                               struct snd_seq_port_info *pinfo)
{
    int num;
    struct snd_seq_client_port *port, *found;

    num = pinfo->addr.port;
    found = NULL;
    read_lock(&client->ports_lock);
    list_for_each_entry(port, &client->ports_list_head, list) {
        if (port->addr.port < num)
            continue;
        if (port->addr.port == num) {
            found = port;
            break;
        }
        if (found == NULL || port->addr.port < found->addr.port)
            found = port;
    }
    if (found) {
        if (found->closing)
            found = NULL;
        else
            snd_use_lock_use(&found->use_lock);
    }
    read_unlock(&client->ports_lock);
    return found;
}


/* initialize snd_seq_port_subs_info */
static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
{
    INIT_LIST_HEAD(&grp->list_head);
    grp->count = 0;
    grp->exclusive = 0;
    rwlock_init(&grp->list_lock);
    init_rwsem(&grp->list_mutex);
    grp->open = NULL;
    grp->close = NULL;
}


/* create a port, port number is returned (-1 on failure) */
struct snd_seq_client_port *snd_seq_create_port(struct snd_seq_client *client,
                        int port)
{
    unsigned long flags;
    struct snd_seq_client_port *new_port, *p;
    int num = -1;
    
    /* sanity check */
    if (snd_BUG_ON(!client))
        return NULL;

    if (client->num_ports >= SNDRV_SEQ_MAX_PORTS - 1) {
        snd_printk(KERN_WARNING "too many ports for client %d\n", client->number);
        return NULL;
    }

    /* create a new port */
    new_port = kzalloc(sizeof(*new_port), GFP_KERNEL);
    if (! new_port) {
        snd_printd("malloc failed for registering client port\n");
        return NULL;    /* failure, out of memory */
    }
    /* init port data */
    new_port->addr.client = client->number;
    new_port->addr.port = -1;
    new_port->owner = THIS_MODULE;
    sprintf(new_port->name, "port-%d", num);
    snd_use_lock_init(&new_port->use_lock);
    port_subs_info_init(&new_port->c_src);
    port_subs_info_init(&new_port->c_dest);

    num = port >= 0 ? port : 0;
    mutex_lock(&client->ports_mutex);
    write_lock_irqsave(&client->ports_lock, flags);
    list_for_each_entry(p, &client->ports_list_head, list) {
        if (p->addr.port > num)
            break;
        if (port < 0) /* auto-probe mode */
            num = p->addr.port + 1;
    }
    /* insert the new port */
    list_add_tail(&new_port->list, &p->list);
    client->num_ports++;
    new_port->addr.port = num;  /* store the port number in the port */
    write_unlock_irqrestore(&client->ports_lock, flags);
    mutex_unlock(&client->ports_mutex);
    sprintf(new_port->name, "port-%d", num);

    return new_port;
}

/* */
enum group_type {
    SRC_LIST, DEST_LIST
};

static int subscribe_port(struct snd_seq_client *client,
              struct snd_seq_client_port *port,
              struct snd_seq_port_subs_info *grp,
              struct snd_seq_port_subscribe *info, int send_ack);
static int unsubscribe_port(struct snd_seq_client *client,
                struct snd_seq_client_port *port,
                struct snd_seq_port_subs_info *grp,
                struct snd_seq_port_subscribe *info, int send_ack);


static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
                           struct snd_seq_client **cp)
{
    struct snd_seq_client_port *p;
    *cp = snd_seq_client_use_ptr(addr->client);
    if (*cp) {
        p = snd_seq_port_use_ptr(*cp, addr->port);
        if (! p) {
            snd_seq_client_unlock(*cp);
            *cp = NULL;
        }
        return p;
    }
    return NULL;
}

/*
 * remove all subscribers on the list
 * this is called from port_delete, for each src and dest list.
 */
static void clear_subscriber_list(struct snd_seq_client *client,
                  struct snd_seq_client_port *port,
                  struct snd_seq_port_subs_info *grp,
                  int grptype)
{
    struct list_head *p, *n;

    list_for_each_safe(p, n, &grp->list_head) {
        struct snd_seq_subscribers *subs;
        struct snd_seq_client *c;
        struct snd_seq_client_port *aport;

        if (grptype == SRC_LIST) {
            subs = list_entry(p, struct snd_seq_subscribers, src_list);
            aport = get_client_port(&subs->info.dest, &c);
        } else {
            subs = list_entry(p, struct snd_seq_subscribers, dest_list);
            aport = get_client_port(&subs->info.sender, &c);
        }
        list_del(p);
        unsubscribe_port(client, port, grp, &subs->info, 0);
        if (!aport) {
            /* looks like the connected port is being deleted.
             * we decrease the counter, and when both ports are deleted
             * remove the subscriber info
             */
            if (atomic_dec_and_test(&subs->ref_count))
                kfree(subs);
        } else {
            /* ok we got the connected port */
            struct snd_seq_port_subs_info *agrp;
            agrp = (grptype == SRC_LIST) ? &aport->c_dest : &aport->c_src;
            down_write(&agrp->list_mutex);
            if (grptype == SRC_LIST)
                list_del(&subs->dest_list);
            else
                list_del(&subs->src_list);
            up_write(&agrp->list_mutex);
            unsubscribe_port(c, aport, agrp, &subs->info, 1);
            kfree(subs);
            snd_seq_port_unlock(aport);
            snd_seq_client_unlock(c);
        }
    }
}

/* delete port data */
static int port_delete(struct snd_seq_client *client,
               struct snd_seq_client_port *port)
{
    /* set closing flag and wait for all port access are gone */
    port->closing = 1;
    snd_use_lock_sync(&port->use_lock); 

    /* clear subscribers info */
    clear_subscriber_list(client, port, &port->c_src, SRC_LIST);
    clear_subscriber_list(client, port, &port->c_dest, DEST_LIST);

    if (port->private_free)
        port->private_free(port->private_data);

    snd_BUG_ON(port->c_src.count != 0);
    snd_BUG_ON(port->c_dest.count != 0);

    kfree(port);
    return 0;
}


/* delete a port with the given port id */
int snd_seq_delete_port(struct snd_seq_client *client, int port)
{
    unsigned long flags;
    struct snd_seq_client_port *found = NULL, *p;

    mutex_lock(&client->ports_mutex);
    write_lock_irqsave(&client->ports_lock, flags);
    list_for_each_entry(p, &client->ports_list_head, list) {
        if (p->addr.port == port) {
            /* ok found.  delete from the list at first */
            list_del(&p->list);
            client->num_ports--;
            found = p;
            break;
        }
    }
    write_unlock_irqrestore(&client->ports_lock, flags);
    mutex_unlock(&client->ports_mutex);
    if (found)
        return port_delete(client, found);
    else
        return -ENOENT;
}

/* delete the all ports belonging to the given client */
int snd_seq_delete_all_ports(struct snd_seq_client *client)
{
    unsigned long flags;
    struct list_head deleted_list;
    struct snd_seq_client_port *port, *tmp;
    
    /* move the port list to deleted_list, and
     * clear the port list in the client data.
     */
    mutex_lock(&client->ports_mutex);
    write_lock_irqsave(&client->ports_lock, flags);
    if (! list_empty(&client->ports_list_head)) {
        list_add(&deleted_list, &client->ports_list_head);
        list_del_init(&client->ports_list_head);
    } else {
        INIT_LIST_HEAD(&deleted_list);
    }
    client->num_ports = 0;
    write_unlock_irqrestore(&client->ports_lock, flags);

    /* remove each port in deleted_list */
    list_for_each_entry_safe(port, tmp, &deleted_list, list) {
        list_del(&port->list);
        snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
        port_delete(client, port);
    }
    mutex_unlock(&client->ports_mutex);
    return 0;
}

/* set port info fields */
int snd_seq_set_port_info(struct snd_seq_client_port * port,
              struct snd_seq_port_info * info)
{
    if (snd_BUG_ON(!port || !info))
        return -EINVAL;

    /* set port name */
    if (info->name[0])
        strlcpy(port->name, info->name, sizeof(port->name));
    
    /* set capabilities */
    port->capability = info->capability;
    
    /* get port type */
    port->type = info->type;

    /* information about supported channels/voices */
    port->midi_channels = info->midi_channels;
    port->midi_voices = info->midi_voices;
    port->synth_voices = info->synth_voices;

    /* timestamping */
    port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
    port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
    port->time_queue = info->time_queue;

    return 0;
}

/* get port info fields */
int snd_seq_get_port_info(struct snd_seq_client_port * port,
              struct snd_seq_port_info * info)
{
    if (snd_BUG_ON(!port || !info))
        return -EINVAL;

    /* get port name */
    strlcpy(info->name, port->name, sizeof(info->name));
    
    /* get capabilities */
    info->capability = port->capability;

    /* get port type */
    info->type = port->type;

    /* information about supported channels/voices */
    info->midi_channels = port->midi_channels;
    info->midi_voices = port->midi_voices;
    info->synth_voices = port->synth_voices;

    /* get subscriber counts */
    info->read_use = port->c_src.count;
    info->write_use = port->c_dest.count;
    
    /* timestamping */
    info->flags = 0;
    if (port->timestamping) {
        info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
        if (port->time_real)
            info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
        info->time_queue = port->time_queue;
    }

    return 0;
}



/*
 * call callback functions (if any):
 * the callbacks are invoked only when the first (for connection) or
 * the last subscription (for disconnection) is done.  Second or later
 * subscription results in increment of counter, but no callback is
 * invoked.
 * This feature is useful if these callbacks are associated with
 * initialization or termination of devices (see seq_midi.c).
 *
 * If callback_all option is set, the callback function is invoked
 * at each connection/disconnection. 
 */

static int subscribe_port(struct snd_seq_client *client,
              struct snd_seq_client_port *port,
              struct snd_seq_port_subs_info *grp,
              struct snd_seq_port_subscribe *info,
              int send_ack)
{
    int err = 0;

    if (!try_module_get(port->owner))
        return -EFAULT;
    grp->count++;
    if (grp->open && (port->callback_all || grp->count == 1)) {
        err = grp->open(port->private_data, info);
        if (err < 0) {
            module_put(port->owner);
            grp->count--;
        }
    }
    if (err >= 0 && send_ack && client->type == USER_CLIENT)
        snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
                           info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);

    return err;
}

static int unsubscribe_port(struct snd_seq_client *client,
                struct snd_seq_client_port *port,
                struct snd_seq_port_subs_info *grp,
                struct snd_seq_port_subscribe *info,
                int send_ack)
{
    int err = 0;

    if (! grp->count)
        return -EINVAL;
    grp->count--;
    if (grp->close && (port->callback_all || grp->count == 0))
        err = grp->close(port->private_data, info);
    if (send_ack && client->type == USER_CLIENT)
        snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
                           info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
    module_put(port->owner);
    return err;
}



/* check if both addresses are identical */
static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
{
    return (r->client == s->client) && (r->port == s->port);
}

/* check the two subscribe info match */
/* if flags is zero, checks only sender and destination addresses */
static int match_subs_info(struct snd_seq_port_subscribe *r,
               struct snd_seq_port_subscribe *s)
{
    if (addr_match(&r->sender, &s->sender) &&
        addr_match(&r->dest, &s->dest)) {
        if (r->flags && r->flags == s->flags)
            return r->queue == s->queue;
        else if (! r->flags)
            return 1;
    }
    return 0;
}


/* connect two ports */
int snd_seq_port_connect(struct snd_seq_client *connector,
             struct snd_seq_client *src_client,
             struct snd_seq_client_port *src_port,
             struct snd_seq_client *dest_client,
             struct snd_seq_client_port *dest_port,
             struct snd_seq_port_subscribe *info)
{
    struct snd_seq_port_subs_info *src = &src_port->c_src;
    struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
    struct snd_seq_subscribers *subs, *s;
    int err, src_called = 0;
    unsigned long flags;
    int exclusive;

    subs = kzalloc(sizeof(*subs), GFP_KERNEL);
    if (! subs)
        return -ENOMEM;

    subs->info = *info;
    atomic_set(&subs->ref_count, 2);

    down_write(&src->list_mutex);
    down_write_nested(&dest->list_mutex, SINGLE_DEPTH_NESTING);

    exclusive = info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE ? 1 : 0;
    err = -EBUSY;
    if (exclusive) {
        if (! list_empty(&src->list_head) || ! list_empty(&dest->list_head))
            goto __error;
    } else {
        if (src->exclusive || dest->exclusive)
            goto __error;
        /* check whether already exists */
        list_for_each_entry(s, &src->list_head, src_list) {
            if (match_subs_info(info, &s->info))
                goto __error;
        }
        list_for_each_entry(s, &dest->list_head, dest_list) {
            if (match_subs_info(info, &s->info))
                goto __error;
        }
    }

    if ((err = subscribe_port(src_client, src_port, src, info,
                  connector->number != src_client->number)) < 0)
        goto __error;
    src_called = 1;

    if ((err = subscribe_port(dest_client, dest_port, dest, info,
                  connector->number != dest_client->number)) < 0)
        goto __error;

    /* add to list */
    write_lock_irqsave(&src->list_lock, flags);
    // write_lock(&dest->list_lock); // no other lock yet
    list_add_tail(&subs->src_list, &src->list_head);
    list_add_tail(&subs->dest_list, &dest->list_head);
    // write_unlock(&dest->list_lock); // no other lock yet
    write_unlock_irqrestore(&src->list_lock, flags);

    src->exclusive = dest->exclusive = exclusive;

    up_write(&dest->list_mutex);
    up_write(&src->list_mutex);
    return 0;

 __error:
    if (src_called)
        unsubscribe_port(src_client, src_port, src, info,
                 connector->number != src_client->number);
    kfree(subs);
    up_write(&dest->list_mutex);
    up_write(&src->list_mutex);
    return err;
}


/* remove the connection */
int snd_seq_port_disconnect(struct snd_seq_client *connector,
                struct snd_seq_client *src_client,
                struct snd_seq_client_port *src_port,
                struct snd_seq_client *dest_client,
                struct snd_seq_client_port *dest_port,
                struct snd_seq_port_subscribe *info)
{
    struct snd_seq_port_subs_info *src = &src_port->c_src;
    struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
    struct snd_seq_subscribers *subs;
    int err = -ENOENT;
    unsigned long flags;

    down_write(&src->list_mutex);
    down_write_nested(&dest->list_mutex, SINGLE_DEPTH_NESTING);

    /* look for the connection */
    list_for_each_entry(subs, &src->list_head, src_list) {
        if (match_subs_info(info, &subs->info)) {
            write_lock_irqsave(&src->list_lock, flags);
            // write_lock(&dest->list_lock);  // no lock yet
            list_del(&subs->src_list);
            list_del(&subs->dest_list);
            // write_unlock(&dest->list_lock);
            write_unlock_irqrestore(&src->list_lock, flags);
            src->exclusive = dest->exclusive = 0;
            unsubscribe_port(src_client, src_port, src, info,
                     connector->number != src_client->number);
            unsubscribe_port(dest_client, dest_port, dest, info,
                     connector->number != dest_client->number);
            kfree(subs);
            err = 0;
            break;
        }
    }

    up_write(&dest->list_mutex);
    up_write(&src->list_mutex);
    return err;
}


/* get matched subscriber */
struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
                              struct snd_seq_addr *dest_addr)
{
    struct snd_seq_subscribers *s, *found = NULL;

    down_read(&src_grp->list_mutex);
    list_for_each_entry(s, &src_grp->list_head, src_list) {
        if (addr_match(dest_addr, &s->info.dest)) {
            found = s;
            break;
        }
    }
    up_read(&src_grp->list_mutex);
    return found;
}

/*
 * Attach a device driver that wants to receive events from the
 * sequencer.  Returns the new port number on success.
 * A driver that wants to receive the events converted to midi, will
 * use snd_seq_midisynth_register_port().
 */
/* exported */
int snd_seq_event_port_attach(int client,
                  struct snd_seq_port_callback *pcbp,
                  int cap, int type, int midi_channels,
                  int midi_voices, char *portname)
{
    struct snd_seq_port_info portinfo;
    int  ret;

    /* Set up the port */
    memset(&portinfo, 0, sizeof(portinfo));
    portinfo.addr.client = client;
    strlcpy(portinfo.name, portname ? portname : "Unamed port",
        sizeof(portinfo.name));

    portinfo.capability = cap;
    portinfo.type = type;
    portinfo.kernel = pcbp;
    portinfo.midi_channels = midi_channels;
    portinfo.midi_voices = midi_voices;

    /* Create it */
    ret = snd_seq_kernel_client_ctl(client,
                    SNDRV_SEQ_IOCTL_CREATE_PORT,
                    &portinfo);

    if (ret >= 0)
        ret = portinfo.addr.port;

    return ret;
}

EXPORT_SYMBOL(snd_seq_event_port_attach);

/*
 * Detach the driver from a port.
 */
/* exported */
int snd_seq_event_port_detach(int client, int port)
{
    struct snd_seq_port_info portinfo;
    int  err;

    memset(&portinfo, 0, sizeof(portinfo));
    portinfo.addr.client = client;
    portinfo.addr.port   = port;
    err = snd_seq_kernel_client_ctl(client,
                    SNDRV_SEQ_IOCTL_DELETE_PORT,
                    &portinfo);

    return err;
}

EXPORT_SYMBOL(snd_seq_event_port_detach);