path: root/udrv/ulinux/uipc.c

/******************************************************************************
 *
 *  Copyright (C) 2009-2012 Broadcom Corporation
 *
 *  This program is the proprietary software of Broadcom Corporation and/or its
 *  licensors, and may only be used, duplicated, modified or distributed
 *  pursuant to the terms and conditions of a separate, written license
 *  agreement executed between you and Broadcom (an "Authorized License").
 *  Except as set forth in an Authorized License, Broadcom grants no license
 *  (express or implied), right to use, or waiver of any kind with respect to
 *  the Software, and Broadcom expressly reserves all rights in and to the
 *  Software and all intellectual property rights therein.
 *  IF YOU HAVE NO AUTHORIZED LICENSE, THEN YOU HAVE NO RIGHT TO USE THIS
 *  SOFTWARE IN ANY WAY, AND SHOULD IMMEDIATELY NOTIFY BROADCOM AND DISCONTINUE
 *  ALL USE OF THE SOFTWARE.
 *
 *  Except as expressly set forth in the Authorized License,
 *
 *  1.     This program, including its structure, sequence and organization,
 *         constitutes the valuable trade secrets of Broadcom, and you shall
 *         use all reasonable efforts to protect the confidentiality thereof,
 *         and to use this information only in connection with your use of
 *         Broadcom integrated circuit products.
 *
 *  2.     TO THE MAXIMUM EXTENT PERMITTED BY LAW, THE SOFTWARE IS PROVIDED
 *         "AS IS" AND WITH ALL FAULTS AND BROADCOM MAKES NO PROMISES,
 *         REPRESENTATIONS OR WARRANTIES, EITHER EXPRESS, IMPLIED, STATUTORY,
 *         OR OTHERWISE, WITH RESPECT TO THE SOFTWARE.  BROADCOM SPECIFICALLY
 *         DISCLAIMS ANY AND ALL IMPLIED WARRANTIES OF TITLE, MERCHANTABILITY,
 *         NONINFRINGEMENT, FITNESS FOR A PARTICULAR PURPOSE, LACK OF VIRUSES,
 *         ACCURACY OR COMPLETENESS, QUIET ENJOYMENT, QUIET POSSESSION OR
 *         CORRESPONDENCE TO DESCRIPTION. YOU ASSUME THE ENTIRE RISK ARISING
 *         OUT OF USE OR PERFORMANCE OF THE SOFTWARE.
 *
 *  3.     TO THE MAXIMUM EXTENT PERMITTED BY LAW, IN NO EVENT SHALL BROADCOM
 *         OR ITS LICENSORS BE LIABLE FOR
 *         (i)   CONSEQUENTIAL, INCIDENTAL, SPECIAL, INDIRECT, OR EXEMPLARY
 *               DAMAGES WHATSOEVER ARISING OUT OF OR IN ANY WAY RELATING TO
 *               YOUR USE OF OR INABILITY TO USE THE SOFTWARE EVEN IF BROADCOM
 *               HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES; OR
 *         (ii)  ANY AMOUNT IN EXCESS OF THE AMOUNT ACTUALLY PAID FOR THE
 *               SOFTWARE ITSELF OR U.S. $1, WHICHEVER IS GREATER. THESE
 *               LIMITATIONS SHALL APPLY NOTWITHSTANDING ANY FAILURE OF
 *               ESSENTIAL PURPOSE OF ANY LIMITED REMEDY.
 *
 *****************************************************************************/

/*****************************************************************************
 *
 *  Filename:      uipc.c
 *
 *  Description:   UIPC implementation for bluedroid
 *
 *****************************************************************************/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>

#include <sys/socket.h>
#include <sys/un.h>
#include <signal.h>
#include <errno.h>
#include <pthread.h>
#include <sys/select.h>
#include <sys/poll.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/prctl.h>


#include "gki.h"
#include "data_types.h"
#include "uipc.h"

#include <cutils/sockets.h>
#include "audio_a2dp_hw.h"

/*****************************************************************************
**  Constants & Macros
******************************************************************************/

#define PCM_FILENAME "/data/test.pcm"

#define MAX(a,b) ((a)>(b)?(a):(b))

#define CASE_RETURN_STR(const) case const: return #const;

#define UIPC_DISCONNECTED (-1)

#define UIPC_LOCK() /*BTIF_TRACE_EVENT1(" %s lock", __FUNCTION__);*/ pthread_mutex_lock(&uipc_main.mutex);
#define UIPC_UNLOCK() /*BTIF_TRACE_EVENT1("%s unlock", __FUNCTION__);*/ pthread_mutex_unlock(&uipc_main.mutex);

/*****************************************************************************
**  Local type definitions
******************************************************************************/

typedef enum {
    UIPC_TASK_FLAG_DISCONNECT_CHAN = 0x1,
} tUIPC_TASK_FLAGS;

typedef struct {
    int srvfd;
    int fd;
    int read_poll_tmo_ms;
    int task_evt_flags;   /* event flags pending to be processed in read task */
    tUIPC_EVENT cond_flags;
    pthread_mutex_t cond_mutex;
    pthread_cond_t  cond;
    tUIPC_RCV_CBACK *cback;
} tUIPC_CHAN;

typedef struct {
    pthread_t tid; /* main thread id */
    int running;
    pthread_mutex_t mutex;

    fd_set active_set;
    fd_set read_set;
    int max_fd;
    int signal_fds[2];

    tUIPC_CHAN ch[UIPC_CH_NUM];
} tUIPC_MAIN;


/*****************************************************************************
**  Static variables
******************************************************************************/

static tUIPC_MAIN uipc_main;


/*****************************************************************************
**  Static functions
******************************************************************************/

static int uipc_close_ch_locked(tUIPC_CH_ID ch_id);

/*****************************************************************************
**  Externs
******************************************************************************/


/*****************************************************************************
**   Helper functions
******************************************************************************/


const char* dump_uipc_event(tUIPC_EVENT event)
{
    switch(event)
    {
        CASE_RETURN_STR(UIPC_OPEN_EVT)
        CASE_RETURN_STR(UIPC_CLOSE_EVT)
        CASE_RETURN_STR(UIPC_RX_DATA_EVT)
        CASE_RETURN_STR(UIPC_RX_DATA_READY_EVT)
        CASE_RETURN_STR(UIPC_TX_DATA_READY_EVT)
        default:
            return "UNKNOWN MSG ID";
    }
}

/*****************************************************************************
**
** Function
**
** Description
**
** Returns
**
*******************************************************************************/

static void uipc_wait(tUIPC_CH_ID ch_id, tUIPC_EVENT wait_event_flags)
{
    int ret;
    tUIPC_CHAN *p = &uipc_main.ch[ch_id];

    //BTIF_TRACE_EVENT2("WAIT UIPC CH %d EVT %x BEGIN", ch_id, wait_event_flags);
    pthread_mutex_lock(&p->cond_mutex);
    p->cond_flags |= wait_event_flags;
    ret = pthread_cond_wait(&p->cond, &p->cond_mutex);
    pthread_mutex_unlock(&p->cond_mutex);
    //BTIF_TRACE_EVENT2("WAIT UIPC CH %d EVT %x DONE", ch_id, wait_event_flags);
}

static void uipc_signal(tUIPC_CH_ID ch_id, tUIPC_EVENT event)
{
    int ret;
    tUIPC_CHAN *p = &uipc_main.ch[ch_id];

    //BTIF_TRACE_EVENT2("SIGNAL UIPC CH %d EVT %x BEGIN", ch_id, dump_uipc_event(event));
    pthread_mutex_lock(&p->cond_mutex);

    if (event & p->cond_flags)
    {
        //BTIF_TRACE_EVENT0("UNBLOCK");
        ret = pthread_cond_signal(&p->cond);
        p->cond_flags = 0;
    }

    pthread_mutex_unlock(&p->cond_mutex);
}



/*****************************************************************************
**   socket helper functions
*****************************************************************************/

static inline int create_server_socket(const char* name)
{
    int s = socket(AF_LOCAL, SOCK_STREAM, 0);

    BTIF_TRACE_EVENT1("create_server_socket %s", name);

    if(socket_local_server_bind(s, name, ANDROID_SOCKET_NAMESPACE_ABSTRACT) < 0)
    {
        BTIF_TRACE_EVENT1("socket failed to create (%s)", strerror(errno));
        return -1;
    }

    if(listen(s, 5) < 0)
    {
        BTIF_TRACE_EVENT1("listen failed", strerror(errno));
        close(s);
        return -1;
    }

    BTIF_TRACE_EVENT1("created socket fd %d", s);
    return s;
}

static int accept_server_socket(int sfd)
{
    struct sockaddr_un remote;
    int fd;
    int t;

    //BTIF_TRACE_EVENT1("accept fd %d", sfd);

    if ((fd = accept(sfd, (struct sockaddr *)&remote, &t)) == -1) {
         BTIF_TRACE_ERROR1("sock accept failed (%s)", strerror(errno));
         return -1;
    }

    //BTIF_TRACE_EVENT1("new fd %d", fd);

    return fd;
}

/*****************************************************************************
**
**   uipc helper functions
**
*****************************************************************************/

static int uipc_main_init(void)
{
    int i;
    const pthread_mutexattr_t attr = PTHREAD_MUTEX_RECURSIVE;
    pthread_mutex_init(&uipc_main.mutex, &attr);

    BTIF_TRACE_EVENT0("### uipc_main_init ###");

    /* setup interrupt socket pair */
    if (socketpair(AF_UNIX, SOCK_STREAM, 0, uipc_main.signal_fds) < 0)
    {
        return -1;
    }

    FD_SET(uipc_main.signal_fds[0], &uipc_main.active_set);
    uipc_main.max_fd = MAX(uipc_main.max_fd, uipc_main.signal_fds[0]);

    for (i=0; i< UIPC_CH_NUM; i++)
    {
        tUIPC_CHAN *p = &uipc_main.ch[i];
        p->srvfd = UIPC_DISCONNECTED;
        p->fd = UIPC_DISCONNECTED;
        p->task_evt_flags = 0;
        pthread_cond_init(&p->cond, NULL);
        pthread_mutex_init(&p->cond_mutex, NULL);
        p->cback = NULL;
    }

    return 0;
}

void uipc_main_cleanup(void)
{
    int i;

    close(uipc_main.signal_fds[0]);
    close(uipc_main.signal_fds[1]);

    /* close any open channels */
    for (i=0; i<UIPC_CH_NUM; i++)
        UIPC_Close(i);
}



/* check pending events in read task */
static void uipc_check_task_flags_locked(void)
{
    int i;

    for (i=0; i<UIPC_CH_NUM; i++)
    {
        //BTIF_TRACE_EVENT2("CHECK TASK FLAGS %x %x",  uipc_main.ch[i].task_evt_flags, UIPC_TASK_FLAG_DISCONNECT_CHAN);
        if (uipc_main.ch[i].task_evt_flags & UIPC_TASK_FLAG_DISCONNECT_CHAN)
        {
            uipc_main.ch[i].task_evt_flags &= ~UIPC_TASK_FLAG_DISCONNECT_CHAN;
            uipc_close_ch_locked(i);
        }

        /* add here */

    }
}


static int uipc_check_fd_locked(tUIPC_CH_ID ch_id)
{
    if (ch_id >= UIPC_CH_NUM)
        return -1;

    //BTIF_TRACE_EVENT2("CHECK SRVFD %d (ch %d)", uipc_main.ch[ch_id].srvfd, ch_id);

    if (FD_ISSET(uipc_main.ch[ch_id].srvfd, &uipc_main.read_set))
    {
        BTIF_TRACE_EVENT1("INCOMING CONNECTION ON CH %d", ch_id);

        uipc_main.ch[ch_id].fd = accept_server_socket(uipc_main.ch[ch_id].srvfd);

        //BTIF_TRACE_EVENT1("NEW FD %d", uipc_main.ch[ch_id].fd);

        if (uipc_main.ch[ch_id].cback)
        {
            /*  if we have a callback we should add this fd to the active set
                and notify user with callback event */
            BTIF_TRACE_EVENT1("ADD FD %d TO ACTIVE SET", uipc_main.ch[ch_id].fd);
            FD_SET(uipc_main.ch[ch_id].fd, &uipc_main.active_set);
            uipc_main.max_fd = MAX(uipc_main.max_fd, uipc_main.ch[ch_id].fd);
        }

        if (uipc_main.ch[ch_id].fd < 0)
        {
            BTIF_TRACE_ERROR2("FAILED TO ACCEPT CH %d (%s)", ch_id, strerror(errno));
            return -1;
        }

        if (uipc_main.ch[ch_id].cback)
            uipc_main.ch[ch_id].cback(ch_id, UIPC_OPEN_EVT);
    }

    //BTIF_TRACE_EVENT2("CHECK FD %d (ch %d)", uipc_main.ch[ch_id].fd, ch_id);

    if (FD_ISSET(uipc_main.ch[ch_id].fd, &uipc_main.read_set))
    {
        //BTIF_TRACE_EVENT1("INCOMING DATA ON CH %d", ch_id);

        if (uipc_main.ch[ch_id].cback)
            uipc_main.ch[ch_id].cback(ch_id, UIPC_RX_DATA_READY_EVT);
    }
    return 0;
}

static void uipc_check_interrupt_locked(void)
{
    if (FD_ISSET(uipc_main.signal_fds[0], &uipc_main.read_set))
    {
        char sig_recv = 0;
        //BTIF_TRACE_EVENT0("UIPC INTERRUPT");
        recv(uipc_main.signal_fds[0], &sig_recv, sizeof(sig_recv), MSG_WAITALL);
    }
}

static inline void uipc_wakeup_locked(void)
{
    char sig_on = 1;
    BTIF_TRACE_EVENT0("UIPC SEND WAKE UP");
    send(uipc_main.signal_fds[1], &sig_on, sizeof(sig_on), 0);
}

static int uipc_setup_server_locked(tUIPC_CH_ID ch_id, char *name, tUIPC_RCV_CBACK *cback)
{
    int fd;

    BTIF_TRACE_EVENT1("SETUP CHANNEL SERVER %d", ch_id);

    if (ch_id >= UIPC_CH_NUM)
        return -1;

    UIPC_LOCK();

    fd = create_server_socket(name);

    if (fd < 0)
    {
        BTIF_TRACE_ERROR2("failed to setup %s", name, strerror(errno));
        UIPC_UNLOCK();
         return -1;
    }

    BTIF_TRACE_EVENT1("ADD SERVER FD TO ACTIVE SET %d", fd);
    FD_SET(fd, &uipc_main.active_set);
    uipc_main.max_fd = MAX(uipc_main.max_fd, fd);

    uipc_main.ch[ch_id].srvfd = fd;
    uipc_main.ch[ch_id].cback = cback;
    uipc_main.ch[ch_id].read_poll_tmo_ms = DEFAULT_READ_POLL_TMO_MS;

    /* trigger main thread to update read set */
    uipc_wakeup_locked();

    UIPC_UNLOCK();

    return 0;
}

static void uipc_flush_ch_locked(tUIPC_CH_ID ch_id)
{
    char buf;
    struct pollfd pfd;
    int ret;

    pfd.events = POLLIN|POLLHUP;
    pfd.fd = uipc_main.ch[ch_id].fd;

    if (uipc_main.ch[ch_id].fd == UIPC_DISCONNECTED)
        return;

    while (1)
    {
        ret = poll(&pfd, 1, 1);
        BTIF_TRACE_EVENT3("uipc_flush_ch_locked polling : fd %d, rxev %x, ret %d", pfd.fd, pfd.revents, ret);

        if (pfd.revents | (POLLERR|POLLHUP))
            return;

        if (ret <= 0)
        {
            BTIF_TRACE_EVENT1("uipc_flush_ch_locked : error (%d)", ret);
            return;
        }
        read(pfd.fd, &buf, 1);
    }
}


static void uipc_flush_locked(tUIPC_CH_ID ch_id)
{
    if (ch_id >= UIPC_CH_NUM)
        return;

    switch(ch_id)
    {
        case UIPC_CH_ID_AV_CTRL:
            uipc_flush_ch_locked(UIPC_CH_ID_AV_CTRL);
            break;

        case UIPC_CH_ID_AV_AUDIO:
            uipc_flush_ch_locked(UIPC_CH_ID_AV_AUDIO);
            break;
    }
}


static int uipc_close_ch_locked(tUIPC_CH_ID ch_id)
{
    int wakeup = 0;

    BTIF_TRACE_EVENT1("CLOSE CHANNEL %d", ch_id);

    if (ch_id >= UIPC_CH_NUM)
        return -1;

    if (ch_id == UIPC_CH_ID_ALL)
    {
        /* shutdown read thread */
        uipc_main.running = 0;
        uipc_wakeup_locked();
        return 0;
    }

    if (uipc_main.ch[ch_id].srvfd != UIPC_DISCONNECTED)
    {
        BTIF_TRACE_EVENT1("CLOSE SERVER (FD %d)", uipc_main.ch[ch_id].srvfd);
        close(uipc_main.ch[ch_id].srvfd);
        FD_CLR(uipc_main.ch[ch_id].srvfd, &uipc_main.active_set);
        uipc_main.ch[ch_id].srvfd = UIPC_DISCONNECTED;
        wakeup = 1;
    }

    if (uipc_main.ch[ch_id].fd != UIPC_DISCONNECTED)
    {
        BTIF_TRACE_EVENT1("CLOSE CONNECTION (FD %d)", uipc_main.ch[ch_id].fd);
        close(uipc_main.ch[ch_id].fd);
        FD_CLR(uipc_main.ch[ch_id].fd, &uipc_main.active_set);
        uipc_main.ch[ch_id].fd = UIPC_DISCONNECTED;
        wakeup = 1;
    }

    /* notify this connection is closed */
    if (uipc_main.ch[ch_id].cback)
        uipc_main.ch[ch_id].cback(ch_id, UIPC_CLOSE_EVT);

    /* trigger main thread update if something was updated */
    if (wakeup)
        uipc_wakeup_locked();

    return 0;
}


void uipc_close_locked(tUIPC_CH_ID ch_id)
{
    if (uipc_main.ch[ch_id].srvfd == UIPC_DISCONNECTED)
    {
        BTIF_TRACE_EVENT1("CHANNEL %d ALREADY CLOSED", ch_id);
        return;
    }

    /* schedule close on this channel */
    uipc_main.ch[ch_id].task_evt_flags |= UIPC_TASK_FLAG_DISCONNECT_CHAN;
    uipc_wakeup_locked();
}


static void uipc_read_task(void *arg)
{
    int ch_id;
    int result;

    prctl(PR_SET_NAME, (unsigned long)"uipc-main", 0, 0, 0);

    while (uipc_main.running)
    {
        uipc_main.read_set = uipc_main.active_set;

        result = select(uipc_main.max_fd+1, &uipc_main.read_set, NULL, NULL, NULL);

        if (result == 0)
        {
            BTIF_TRACE_EVENT0("select timeout");
            continue;
        }
        else if (result < 0)
        {
            BTIF_TRACE_EVENT1("select failed %s", strerror(errno));
            continue;
        }

        UIPC_LOCK();

        /* clear any wakeup interrupt */
        uipc_check_interrupt_locked();

        /* check pending task events */
        uipc_check_task_flags_locked();

        /* make sure we service audio channel first */
        uipc_check_fd_locked(UIPC_CH_ID_AV_AUDIO);

        /* check for other connections */
        for (ch_id = 0; ch_id < UIPC_CH_NUM; ch_id++)
        {
            if (ch_id != UIPC_CH_ID_AV_AUDIO)
                uipc_check_fd_locked(ch_id);
        }

        UIPC_UNLOCK();
    }

    BTIF_TRACE_EVENT0("UIPC READ THEAD EXITING");

    uipc_main_cleanup();
}


int uipc_start_main_server_thread(void)
{
    uipc_main.running = 1;

    if (pthread_create(&uipc_main.tid, (const pthread_attr_t *) NULL, (void*)uipc_read_task, NULL) < 0)
    {
        BTIF_TRACE_ERROR1("uipc_thread_create pthread_create failed:%d", errno);
        return -1;
    }

    return 0;
}

/*******************************************************************************
 **
 ** Function         UIPC_Init
 **
 ** Description      Initialize UIPC module
 **
 ** Returns          void
 **
 *******************************************************************************/

UDRV_API void UIPC_Init(void *p_data)
{
    BTIF_TRACE_DEBUG0("UIPC_Init");

    memset(&uipc_main, 0, sizeof(tUIPC_MAIN));

    uipc_main_init();

    uipc_start_main_server_thread();
}

/*******************************************************************************
 **
 ** Function         UIPC_Open
 **
 ** Description      Open UIPC interface
 **
 ** Returns          TRUE in case of success, FALSE in case of failure.
 **
 *******************************************************************************/
UDRV_API BOOLEAN UIPC_Open(tUIPC_CH_ID ch_id, tUIPC_RCV_CBACK *p_cback)
{
    BTIF_TRACE_DEBUG2("UIPC_Open : ch_id %d, p_cback %x", ch_id, p_cback);

    UIPC_LOCK();

    if (ch_id >= UIPC_CH_NUM)
    {
        UIPC_UNLOCK();
        return FALSE;
    }

    if (uipc_main.ch[ch_id].srvfd != UIPC_DISCONNECTED)
    {
        BTIF_TRACE_EVENT1("CHANNEL %d ALREADY OPEN", ch_id);
        UIPC_UNLOCK();
        return 0;
    }

    switch(ch_id)
    {
        case UIPC_CH_ID_AV_CTRL:
            uipc_setup_server_locked(ch_id, A2DP_CTRL_PATH, p_cback);
            break;

        case UIPC_CH_ID_AV_AUDIO:
            uipc_setup_server_locked(ch_id, A2DP_DATA_PATH, p_cback);
            break;
    }

    UIPC_UNLOCK();

    return TRUE;
}

/*******************************************************************************
 **
 ** Function         UIPC_Close
 **
 ** Description      Close UIPC interface
 **
 ** Returns          void
 **
 *******************************************************************************/

UDRV_API void UIPC_Close(tUIPC_CH_ID ch_id)
{
    BTIF_TRACE_DEBUG1("UIPC_Close : ch_id %d", ch_id);

    UIPC_LOCK();
    uipc_close_locked(ch_id);
    UIPC_UNLOCK();
}

/*******************************************************************************
 **
 ** Function         UIPC_SendBuf
 **
 ** Description      Called to transmit a message over UIPC.
 **                  Message buffer will be freed by UIPC_SendBuf.
 **
 ** Returns          TRUE in case of success, FALSE in case of failure.
 **
 *******************************************************************************/
UDRV_API BOOLEAN UIPC_SendBuf(tUIPC_CH_ID ch_id, BT_HDR *p_msg)
{
    BTIF_TRACE_DEBUG1("UIPC_SendBuf : ch_id %d NOT IMPLEMENTED", ch_id);

    UIPC_LOCK();

    /* currently not used */

    UIPC_UNLOCK();

    return FALSE;
}

/*******************************************************************************
 **
 ** Function         UIPC_Send
 **
 ** Description      Called to transmit a message over UIPC.
 **
 ** Returns          TRUE in case of success, FALSE in case of failure.
 **
 *******************************************************************************/
UDRV_API BOOLEAN UIPC_Send(tUIPC_CH_ID ch_id, UINT16 msg_evt, UINT8 *p_buf,
        UINT16 msglen)
{
    int n;

    BTIF_TRACE_DEBUG2("UIPC_Send : ch_id:%d %d bytes", ch_id, msglen);

    UIPC_LOCK();

    if (write(uipc_main.ch[ch_id].fd, p_buf, msglen) < 0)
    {
        BTIF_TRACE_ERROR1("failed to write (%s)", strerror(errno));
    }

    UIPC_UNLOCK();

    return FALSE;
}

/*******************************************************************************
 **
 ** Function         UIPC_ReadBuf
 **
 ** Description      Called to read a message from UIPC.
 **
 ** Returns          void
 **
 *******************************************************************************/
UDRV_API void UIPC_ReadBuf(tUIPC_CH_ID ch_id, BT_HDR *p_msg)
{
    BTIF_TRACE_DEBUG1("UIPC_ReadBuf : ch_id:%d NOT IMPLEMENTED", ch_id);

    UIPC_LOCK();
    UIPC_UNLOCK();
}

/*******************************************************************************
 **
 ** Function         UIPC_Read
 **
 ** Description      Called to read a message from UIPC.
 **
 ** Returns          return the number of bytes read.
 **
 *******************************************************************************/

UDRV_API UINT32 UIPC_Read(tUIPC_CH_ID ch_id, UINT16 *p_msg_evt, UINT8 *p_buf, UINT32 len)
{
    int n;
    int n_read = 0;
    int fd = uipc_main.ch[ch_id].fd;
    struct pollfd pfd;

    if (ch_id >= UIPC_CH_NUM)
    {
        BTIF_TRACE_ERROR1("UIPC_Read : invalid ch id %d", ch_id);
        return 0;
    }

    if (fd == UIPC_DISCONNECTED)
    {
        BTIF_TRACE_ERROR1("UIPC_Read : channel %d closed", ch_id);
        return 0;
    }

    //BTIF_TRACE_DEBUG4("UIPC_Read : ch_id %d, len %d, fd %d, polltmo %d", ch_id, len,
    //        fd, uipc_main.ch[ch_id].read_poll_tmo_ms);

    while (n_read < (int)len)
    {
        pfd.fd = fd;
        pfd.events = POLLIN|POLLHUP;

        /* make sure there is data prior to attempting read */
        if (poll(&pfd, 1, uipc_main.ch[ch_id].read_poll_tmo_ms) == 0)
        {
            BTIF_TRACE_EVENT1("poll timeout (%d ms)", uipc_main.ch[ch_id].read_poll_tmo_ms);
            return 0;
        }

        //BTIF_TRACE_EVENT1("poll revents %x", pfd.revents);

        if (pfd.revents & (POLLHUP|POLLNVAL) )
        {
            BTIF_TRACE_EVENT0("poll : channel detached remotely");
            UIPC_LOCK();
            uipc_close_locked(ch_id);
            UIPC_UNLOCK();
            return 0;
        }

        UIPC_UNLOCK();

        n = recv(fd, p_buf, len, 0);

        //BTIF_TRACE_EVENT1("read %d bytes", n);

        if (n == 0)
        {
            BTIF_TRACE_EVENT0("UIPC_Read : channel detached remotely");
            UIPC_LOCK();
            uipc_close_locked(ch_id);
            UIPC_UNLOCK();
            return 0;
        }

        if (n < 0)
        {
            BTIF_TRACE_EVENT1("UIPC_Read : read failed (%s)", strerror(errno));
            return 0;
        }

        n_read+=n;

    }

    return n_read;
}

/*******************************************************************************
**
** Function         UIPC_Ioctl
**
** Description      Called to control UIPC.
**
** Returns          void
**
*******************************************************************************/

UDRV_API extern BOOLEAN UIPC_Ioctl(tUIPC_CH_ID ch_id, UINT32 request, void *param)
{
    BTIF_TRACE_DEBUG2("#### UIPC_Ioctl : ch_id %d, request %d ####", ch_id, request);

    UIPC_LOCK();

    switch(request)
    {
        case UIPC_REQ_RX_FLUSH:
            uipc_flush_locked(ch_id);
            break;

        case UIPC_REG_CBACK:
            //BTIF_TRACE_EVENT3("register callback ch %d srvfd %d, fd %d", ch_id, uipc_main.ch[ch_id].srvfd, uipc_main.ch[ch_id].fd);
            uipc_main.ch[ch_id].cback = (tUIPC_RCV_CBACK*)param;
            break;

        case UIPC_REG_REMOVE_ACTIVE_READSET:

            /* user will read data directly and not use select loop */
            if (uipc_main.ch[ch_id].fd != UIPC_DISCONNECTED)
            {
                /* remove this channel from active set */
                FD_CLR(uipc_main.ch[ch_id].fd, &uipc_main.active_set);

                /* refresh active set */
                uipc_wakeup_locked();
            }
            break;

        case UIPC_SET_READ_POLL_TMO:
            uipc_main.ch[ch_id].read_poll_tmo_ms = (int)param;
            BTIF_TRACE_EVENT2("UIPC_SET_READ_POLL_TMO : CH %d, TMO %d ms", ch_id, uipc_main.ch[ch_id].read_poll_tmo_ms );
            break;

        default:
            BTIF_TRACE_EVENT1("UIPC_Ioctl : request not handled (%d)", request);
            break;
    }

    UIPC_UNLOCK();

    return FALSE;
}