stack/btm/btm_pm.cc

/******************************************************************************
 *
 *  Copyright (C) 2000-2012 Broadcom Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at:
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 ******************************************************************************/

/*****************************************************************************
 *
 *  This file contains functions that manages ACL link modes.
 *  This includes operations such as active, hold,
 *  park and sniff modes.
 *
 *  This module contains both internal and external (API)
 *  functions. External (API) functions are distinguishable
 *  by their names beginning with uppercase BTM.
 *
 *****************************************************************************/

#define LOG_TAG "bt_btm_pm"

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

#include "bt_types.h"
#include "bt_utils.h"
#include "btm_api.h"
#include "btm_int.h"
#include "btu.h"
#include "bt_common.h"
#include "hcidefs.h"
#include "hcimsgs.h"
#include "l2c_int.h"
#include "osi/include/log.h"
#include "osi/include/osi.h"

/*****************************************************************************/
/*      to handle different modes                                            */
/*****************************************************************************/
#define BTM_PM_STORED_MASK      0x80 /* set this mask if the command is stored */
#define BTM_PM_NUM_SET_MODES    3 /* only hold, sniff & park */

/* Usage:  (ptr_features[ offset ] & mask )?true:false */
/* offset to supported feature */
const uint8_t btm_pm_mode_off[BTM_PM_NUM_SET_MODES] = {0,    0,    1};
/* mask to supported feature */
const uint8_t btm_pm_mode_msk[BTM_PM_NUM_SET_MODES] = {0x40, 0x80, 0x01};

#define BTM_PM_GET_MD1      1
#define BTM_PM_GET_MD2      2
#define BTM_PM_GET_COMP     3

const uint8_t btm_pm_md_comp_matrix[BTM_PM_NUM_SET_MODES*BTM_PM_NUM_SET_MODES] =
{
    BTM_PM_GET_COMP,
    BTM_PM_GET_MD2,
    BTM_PM_GET_MD2,

    BTM_PM_GET_MD1,
    BTM_PM_GET_COMP,
    BTM_PM_GET_MD1,

    BTM_PM_GET_MD1,
    BTM_PM_GET_MD2,
    BTM_PM_GET_COMP
};

/* function prototype */
static int btm_pm_find_acl_ind(BD_ADDR remote_bda);
static tBTM_STATUS btm_pm_snd_md_req( uint8_t pm_id, int link_ind, tBTM_PM_PWR_MD *p_mode );
static const char *mode_to_string(tBTM_PM_MODE mode);

/*
#ifdef BTM_PM_DEBUG
#undef BTM_PM_DEBUG
#define BTM_PM_DEBUG    true
#endif
*/

#if (BTM_PM_DEBUG == TRUE)
const char * btm_pm_state_str[] =
{
    "pm_active_state",
    "pm_hold_state",
    "pm_sniff_state",
    "pm_park_state",
    "pm_pend_state"
};

const char * btm_pm_event_str[] =
{
    "pm_set_mode_event",
    "pm_hci_sts_event",
    "pm_mod_chg_event",
    "pm_update_event"
};

const char * btm_pm_action_str[] =
{
    "pm_set_mode_action",
    "pm_update_db_action",
    "pm_mod_chg_action",
    "pm_hci_sts_action",
    "pm_update_action"
};
#endif  // BTM_PM_DEBUG

/*****************************************************************************/
/*                     P U B L I C  F U N C T I O N S                        */
/*****************************************************************************/
/*******************************************************************************
 *
 * Function         BTM_PmRegister
 *
 * Description      register or deregister with power manager
 *
 * Returns          BTM_SUCCESS if successful,
 *                  BTM_NO_RESOURCES if no room to hold registration
 *                  BTM_ILLEGAL_VALUE
 *
 ******************************************************************************/
tBTM_STATUS BTM_PmRegister (uint8_t mask, uint8_t *p_pm_id, tBTM_PM_STATUS_CBACK *p_cb)
{
    int xx;

    /* de-register */
    if(mask & BTM_PM_DEREG)
    {
        if(*p_pm_id >= BTM_MAX_PM_RECORDS)
            return BTM_ILLEGAL_VALUE;
        btm_cb.pm_reg_db[*p_pm_id].mask = BTM_PM_REC_NOT_USED;
        return BTM_SUCCESS;
    }

    for(xx=0; xx<BTM_MAX_PM_RECORDS; xx++)
    {
        /* find an unused entry */
        if(btm_cb.pm_reg_db[xx].mask == BTM_PM_REC_NOT_USED)
        {
            /* if register for notification, should provide callback routine */
            if(mask & BTM_PM_REG_NOTIF)
            {
                if(p_cb == NULL)
                    return BTM_ILLEGAL_VALUE;
                btm_cb.pm_reg_db[xx].cback = p_cb;
            }
            btm_cb.pm_reg_db[xx].mask = mask;
            *p_pm_id = xx;
            return BTM_SUCCESS;
        }
    }

    return BTM_NO_RESOURCES;
}

/*******************************************************************************
 *
 * Function         BTM_SetPowerMode
 *
 * Description      store the mode in control block or
 *                  alter ACL connection behavior.
 *
 * Returns          BTM_SUCCESS if successful,
 *                  BTM_UNKNOWN_ADDR if bd addr is not active or bad
 *
 ******************************************************************************/
tBTM_STATUS BTM_SetPowerMode (uint8_t pm_id, BD_ADDR remote_bda, tBTM_PM_PWR_MD *p_mode)
{
    uint8_t             *p_features;
    int               ind, acl_ind;
    tBTM_PM_MCB *p_cb = NULL;   /* per ACL link */
    tBTM_PM_MODE        mode;
    int                 temp_pm_id;

    if(pm_id >= BTM_MAX_PM_RECORDS)
        pm_id = BTM_PM_SET_ONLY_ID;

    if(p_mode == NULL)
        return BTM_ILLEGAL_VALUE;

    BTM_TRACE_API( "BTM_SetPowerMode: pm_id %d BDA: %08x mode:0x%x", pm_id,
                   (remote_bda[2]<<24)+(remote_bda[3]<<16)+(remote_bda[4]<<8)+remote_bda[5], p_mode->mode);

    /* take out the force bit */
    mode = p_mode->mode & ~BTM_PM_MD_FORCE;

    acl_ind = btm_pm_find_acl_ind(remote_bda);
    if(acl_ind == MAX_L2CAP_LINKS)
        return (BTM_UNKNOWN_ADDR);

    p_cb = &(btm_cb.pm_mode_db[acl_ind]);

    if(mode != BTM_PM_MD_ACTIVE)
    {
        /* check if the requested mode is supported */
        ind = mode - BTM_PM_MD_HOLD; /* make it base 0 */
        p_features = BTM_ReadLocalFeatures();
        if( !(p_features[ btm_pm_mode_off[ind] ] & btm_pm_mode_msk[ind] ) )
            return BTM_MODE_UNSUPPORTED;
    }

    if(mode == p_cb->state) /* the requested mode is current mode */
    {
        /* already in the requested mode and the current interval has less latency than the max */
        if( (mode == BTM_PM_MD_ACTIVE) ||
            ((p_mode->mode & BTM_PM_MD_FORCE) && (p_mode->max >= p_cb->interval) && (p_mode->min <= p_cb->interval)) ||
            ((p_mode->mode & BTM_PM_MD_FORCE)==0 && (p_mode->max >= p_cb->interval)) )
        {
            BTM_TRACE_DEBUG( "BTM_SetPowerMode: mode:0x%x interval %d max:%d, min:%d", p_mode->mode, p_cb->interval, p_mode->max, p_mode->min);
            return BTM_SUCCESS;
        }
    }

    temp_pm_id = pm_id;
    if(pm_id == BTM_PM_SET_ONLY_ID)
        temp_pm_id = BTM_MAX_PM_RECORDS;

    /* update mode database */
    if( ((pm_id != BTM_PM_SET_ONLY_ID) &&
         (btm_cb.pm_reg_db[pm_id].mask & BTM_PM_REG_SET))
       || ((pm_id == BTM_PM_SET_ONLY_ID) && (btm_cb.pm_pend_link != MAX_L2CAP_LINKS)) )
    {
#if (BTM_PM_DEBUG == TRUE)
    BTM_TRACE_DEBUG( "BTM_SetPowerMode: Saving cmd acl_ind %d temp_pm_id %d", acl_ind,temp_pm_id);
#endif  // BTM_PM_DEBUG
        /* Make sure mask is set to BTM_PM_REG_SET */
        btm_cb.pm_reg_db[temp_pm_id].mask |= BTM_PM_REG_SET;
        *(&p_cb->req_mode[temp_pm_id]) = *((tBTM_PM_PWR_MD *)p_mode);
        p_cb->chg_ind = true;
    }

#if (BTM_PM_DEBUG == TRUE)
    BTM_TRACE_DEBUG( "btm_pm state:0x%x, pm_pend_link: %d", p_cb->state, btm_cb.pm_pend_link);
#endif  // BTM_PM_DEBUG
    /* if mode == hold or pending, return */
    if( (p_cb->state == BTM_PM_STS_HOLD) ||
        (p_cb->state ==  BTM_PM_STS_PENDING) ||
        (btm_cb.pm_pend_link != MAX_L2CAP_LINKS) ) /* command pending */
    {
        if(acl_ind != btm_cb.pm_pend_link)
        {
            /* set the stored mask */
            p_cb->state |= BTM_PM_STORED_MASK;
            BTM_TRACE_DEBUG( "btm_pm state stored:%d",acl_ind);
        }
        return BTM_CMD_STORED;
    }

    return btm_pm_snd_md_req(pm_id, acl_ind, p_mode);
}

/*******************************************************************************
 *
 * Function         BTM_ReadPowerMode
 *
 * Description      This returns the current mode for a specific
 *                  ACL connection.
 *
 * Input Param      remote_bda - device address of desired ACL connection
 *
 * Output Param     p_mode - address where the current mode is copied into.
 *                          BTM_ACL_MODE_NORMAL
 *                          BTM_ACL_MODE_HOLD
 *                          BTM_ACL_MODE_SNIFF
 *                          BTM_ACL_MODE_PARK
 *                          (valid only if return code is BTM_SUCCESS)
 *
 * Returns          BTM_SUCCESS if successful,
 *                  BTM_UNKNOWN_ADDR if bd addr is not active or bad
 *
 ******************************************************************************/
tBTM_STATUS BTM_ReadPowerMode (BD_ADDR remote_bda, tBTM_PM_MODE *p_mode)
{
    int acl_ind;

    acl_ind = btm_pm_find_acl_ind(remote_bda);
    if(acl_ind == MAX_L2CAP_LINKS)
        return (BTM_UNKNOWN_ADDR);

    *p_mode = btm_cb.pm_mode_db[acl_ind].state;
    return BTM_SUCCESS;
}

/*******************************************************************************
 *
 * Function         btm_read_power_mode_state
 *
 * Description      This returns the current pm state for a specific
 *                  ACL connection.
 *
 * Input Param      remote_bda - device address of desired ACL connection
 *
 * Output Param     pmState - address where the current  pm state is copied into.
 *                          BTM_PM_ST_ACTIVE
 *                          BTM_PM_ST_HOLD
 *                          BTM_PM_ST_SNIFF
 *                          BTM_PM_ST_PARK
 *                          BTM_PM_ST_PENDING
 *                          (valid only if return code is BTM_SUCCESS)
 *
 * Returns          BTM_SUCCESS if successful,
 *                  BTM_UNKNOWN_ADDR if bd addr is not active or bad
 *
 ******************************************************************************/
tBTM_STATUS btm_read_power_mode_state (BD_ADDR remote_bda, tBTM_PM_STATE *pmState)
{
    int acl_ind = btm_pm_find_acl_ind(remote_bda);

    if( acl_ind == MAX_L2CAP_LINKS)
        return (BTM_UNKNOWN_ADDR);

    *pmState = btm_cb.pm_mode_db[acl_ind].state;
    return BTM_SUCCESS;
}

/*******************************************************************************
 *
 * Function         BTM_SetSsrParams
 *
 * Description      This sends the given SSR parameters for the given ACL
 *                  connection if it is in ACTIVE mode.
 *
 * Input Param      remote_bda - device address of desired ACL connection
 *                  max_lat    - maximum latency (in 0.625ms)(0-0xFFFE)
 *                  min_rmt_to - minimum remote timeout
 *                  min_loc_to - minimum local timeout
 *
 *
 * Returns          BTM_SUCCESS if the HCI command is issued successful,
 *                  BTM_UNKNOWN_ADDR if bd addr is not active or bad
 *                  BTM_CMD_STORED if the command is stored
 *
 ******************************************************************************/
tBTM_STATUS BTM_SetSsrParams (BD_ADDR remote_bda, uint16_t max_lat,
                              uint16_t min_rmt_to, uint16_t min_loc_to)
{
#if (BTM_SSR_INCLUDED == TRUE)
    int acl_ind;
    tBTM_PM_MCB *p_cb;

    acl_ind = btm_pm_find_acl_ind(remote_bda);
    if(acl_ind == MAX_L2CAP_LINKS)
        return (BTM_UNKNOWN_ADDR);

    if(BTM_PM_STS_ACTIVE == btm_cb.pm_mode_db[acl_ind].state ||
        BTM_PM_STS_SNIFF == btm_cb.pm_mode_db[acl_ind].state)
    {
        btsnd_hcic_sniff_sub_rate(btm_cb.acl_db[acl_ind].hci_handle, max_lat,
                                  min_rmt_to, min_loc_to);
        return BTM_SUCCESS;
    }
    p_cb = &btm_cb.pm_mode_db[acl_ind];
    p_cb->max_lat       = max_lat;
    p_cb->min_rmt_to    = min_rmt_to;
    p_cb->min_loc_to    = min_loc_to;
    return BTM_CMD_STORED;
#else
    return BTM_ILLEGAL_ACTION;
#endif  // BTM_SSR_INCLUDED
}

/*******************************************************************************
 *
 * Function         btm_pm_reset
 *
 * Description      as a part of the BTM reset process.
 *
 * Returns          void
 *
 ******************************************************************************/
void btm_pm_reset(void)
{
    int xx;
    tBTM_PM_STATUS_CBACK *cb = NULL;

    /* clear the pending request for application */
    if( (btm_cb.pm_pend_id != BTM_PM_SET_ONLY_ID) &&
        (btm_cb.pm_reg_db[btm_cb.pm_pend_id].mask & BTM_PM_REG_NOTIF) )
    {
        cb = btm_cb.pm_reg_db[btm_cb.pm_pend_id].cback;
    }

    /* clear the register record */
    for(xx=0; xx<BTM_MAX_PM_RECORDS; xx++)
    {
        btm_cb.pm_reg_db[xx].mask = BTM_PM_REC_NOT_USED;
    }

    if(cb != NULL && btm_cb.pm_pend_link < MAX_L2CAP_LINKS)
        (*cb)(btm_cb.acl_db[btm_cb.pm_pend_link].remote_addr, BTM_PM_STS_ERROR, BTM_DEV_RESET, 0);

    /* no command pending */
    btm_cb.pm_pend_link = MAX_L2CAP_LINKS;
}

/*******************************************************************************
 *
 * Function         btm_pm_sm_alloc
 *
 * Description      This function initializes the control block of an ACL link.
 *                  It is called when an ACL connection is created.
 *
 * Returns          void
 *
 ******************************************************************************/
void btm_pm_sm_alloc(uint8_t ind)
{
    tBTM_PM_MCB *p_db = &btm_cb.pm_mode_db[ind];   /* per ACL link */
    memset (p_db, 0, sizeof(tBTM_PM_MCB));
    p_db->state = BTM_PM_ST_ACTIVE;
#if (BTM_PM_DEBUG == TRUE)
    BTM_TRACE_DEBUG( "btm_pm_sm_alloc ind:%d st:%d", ind, p_db->state);
#endif  // BTM_PM_DEBUG
}

/*******************************************************************************
 *
 * Function         btm_pm_find_acl_ind
 *
 * Description      This function initializes the control block of an ACL link.
 *                  It is called when an ACL connection is created.
 *
 * Returns          void
 *
 ******************************************************************************/
static int btm_pm_find_acl_ind(BD_ADDR remote_bda)
{
    tACL_CONN   *p = &btm_cb.acl_db[0];
    uint8_t xx;

    for (xx = 0; xx < MAX_L2CAP_LINKS; xx++, p++)
    {
        if ((p->in_use) && (!memcmp (p->remote_addr, remote_bda, BD_ADDR_LEN)) &&
            p->transport == BT_TRANSPORT_BR_EDR)
        {
#if (BTM_PM_DEBUG == TRUE)
            BTM_TRACE_DEBUG( "btm_pm_find_acl_ind ind:%d, st:%d", xx, btm_cb.pm_mode_db[xx].state);
#endif  // BTM_PM_DEBUG
            break;
        }
    }
    return xx;
}

/*******************************************************************************
 *
 * Function     btm_pm_compare_modes
 * Description  get the "more active" mode of the 2
 * Returns      void
 *
 ******************************************************************************/
static tBTM_PM_PWR_MD * btm_pm_compare_modes(tBTM_PM_PWR_MD *p_md1, tBTM_PM_PWR_MD *p_md2, tBTM_PM_PWR_MD *p_res)
{
    uint8_t res;

    if(p_md1 == NULL)
    {
        *p_res = *p_md2;
        p_res->mode &= ~BTM_PM_MD_FORCE;

        return p_md2;
    }

    if(p_md2->mode == BTM_PM_MD_ACTIVE || p_md1->mode == BTM_PM_MD_ACTIVE)
    {
        return NULL;
    }

    /* check if force bit is involved */
    if(p_md1->mode & BTM_PM_MD_FORCE)
    {
        *p_res = *p_md1;
        p_res->mode &= ~BTM_PM_MD_FORCE;
        return p_res;
    }

    if(p_md2->mode & BTM_PM_MD_FORCE)
    {
        *p_res = *p_md2;
        p_res->mode &= ~BTM_PM_MD_FORCE;
        return p_res;
    }

    res = (p_md1->mode - 1) * BTM_PM_NUM_SET_MODES + (p_md2->mode - 1);
    res = btm_pm_md_comp_matrix[res];
    switch(res)
    {
    case BTM_PM_GET_MD1:
        *p_res = *p_md1;
        return p_md1;

    case BTM_PM_GET_MD2:
        *p_res = *p_md2;
        return p_md2;

    case BTM_PM_GET_COMP:
        p_res->mode = p_md1->mode;
        /* min of the two */
        p_res->max  = (p_md1->max < p_md2->max)? (p_md1->max) : (p_md2->max);
        /* max of the two */
        p_res->min  = (p_md1->min > p_md2->min)? (p_md1->min) : (p_md2->min);

        /* the intersection is NULL */
        if( p_res->max < p_res->min)
            return NULL;

        if(p_res->mode == BTM_PM_MD_SNIFF)
        {
            /* max of the two */
            p_res->attempt  = (p_md1->attempt > p_md2->attempt)? (p_md1->attempt) : (p_md2->attempt);
            p_res->timeout  = (p_md1->timeout > p_md2->timeout)? (p_md1->timeout) : (p_md2->timeout);
        }
        return p_res;
    }
    return NULL;
}

/*******************************************************************************
 *
 * Function     btm_pm_get_set_mode
 * Description  get the resulting mode from the registered parties, then compare it
 *              with the requested mode, if the command is from an unregistered party.
 * Returns      void
 *
 ******************************************************************************/
static tBTM_PM_MODE btm_pm_get_set_mode(uint8_t pm_id, tBTM_PM_MCB *p_cb, tBTM_PM_PWR_MD *p_mode, tBTM_PM_PWR_MD *p_res)
{
    int   xx, loop_max;
    tBTM_PM_PWR_MD *p_md = NULL;

    if(p_mode != NULL && p_mode->mode & BTM_PM_MD_FORCE)
    {
        *p_res = *p_mode;
        p_res->mode &= ~BTM_PM_MD_FORCE;
        return p_res->mode;
    }

    if(!p_mode)
        loop_max = BTM_MAX_PM_RECORDS+1;
    else
        loop_max = BTM_MAX_PM_RECORDS;

    for( xx=0; xx<loop_max; xx++)
    {
        /* g through all the registered "set" parties */
        if(btm_cb.pm_reg_db[xx].mask & BTM_PM_REG_SET)
        {
            if(p_cb->req_mode[xx].mode == BTM_PM_MD_ACTIVE)
            {
                /* if at least one registered (SET) party says ACTIVE, stay active */
                return BTM_PM_MD_ACTIVE;
            }
            else
            {
                /* if registered parties give conflicting information, stay active */
                if( (btm_pm_compare_modes(p_md, &p_cb->req_mode[xx], p_res)) == NULL)
                    return BTM_PM_MD_ACTIVE;
                p_md = p_res;
            }
        }
    }

    /* if the resulting mode is NULL(nobody registers SET), use the requested mode */
    if(p_md == NULL)
    {
        if(p_mode)
            *p_res = *((tBTM_PM_PWR_MD *)p_mode);
        else /* p_mode is NULL when btm_pm_snd_md_req is called from btm_pm_proc_mode_change */
            return BTM_PM_MD_ACTIVE;
    }
    else
    {
        /* if the command is from unregistered party,
           compare the resulting mode from registered party*/
        if( (pm_id == BTM_PM_SET_ONLY_ID) &&
            ((btm_pm_compare_modes(p_mode, p_md, p_res)) == NULL) )
            return BTM_PM_MD_ACTIVE;
    }

    return p_res->mode;
}

/*******************************************************************************
 *
 * Function     btm_pm_snd_md_req
 * Description  get the resulting mode and send the resuest to host controller
 * Returns      tBTM_STATUS
 *, bool    *p_chg_ind
 ******************************************************************************/
static tBTM_STATUS btm_pm_snd_md_req(uint8_t pm_id, int link_ind, tBTM_PM_PWR_MD *p_mode)
{
    tBTM_PM_PWR_MD  md_res;
    tBTM_PM_MODE    mode;
    tBTM_PM_MCB *p_cb = &btm_cb.pm_mode_db[link_ind];
    bool         chg_ind = false;

    mode = btm_pm_get_set_mode(pm_id, p_cb, p_mode, &md_res);
    md_res.mode = mode;

#if (BTM_PM_DEBUG == TRUE)
    BTM_TRACE_DEBUG( "btm_pm_snd_md_req link_ind:%d, mode: %d",
        link_ind, mode);
#endif  // BTM_PM_DEBUG

    if( p_cb->state == mode)
    {
        /* already in the resulting mode */
        if( (mode == BTM_PM_MD_ACTIVE) ||
            ((md_res.max >= p_cb->interval) && (md_res.min <= p_cb->interval)) )
            return BTM_CMD_STORED;
        /* Otherwise, needs to wake, then sleep */
        chg_ind = true;
    }
    p_cb->chg_ind = chg_ind;

     /* cannot go directly from current mode to resulting mode. */
    if( mode != BTM_PM_MD_ACTIVE && p_cb->state != BTM_PM_MD_ACTIVE)
        p_cb->chg_ind = true; /* needs to wake, then sleep */

    if(p_cb->chg_ind == true) /* needs to wake first */
        md_res.mode = BTM_PM_MD_ACTIVE;
#if (BTM_SSR_INCLUDED == TRUE)
    else if(BTM_PM_MD_SNIFF == md_res.mode && p_cb->max_lat)
    {
        btsnd_hcic_sniff_sub_rate(btm_cb.acl_db[link_ind].hci_handle, p_cb->max_lat,
                                  p_cb->min_rmt_to, p_cb->min_loc_to);
        p_cb->max_lat = 0;
    }
#endif  // BTM_SSR_INCLUDED
    /* Default is failure */
    btm_cb.pm_pend_link = MAX_L2CAP_LINKS;

    /* send the appropriate HCI command */
    btm_cb.pm_pend_id   = pm_id;

#if (BTM_PM_DEBUG == TRUE)
    BTM_TRACE_DEBUG("btm_pm_snd_md_req state:0x%x, link_ind: %d", p_cb->state, link_ind);
#endif  // BTM_PM_DEBUG

    BTM_TRACE_DEBUG("%s switching from %s to %s.", __func__,
                    mode_to_string(p_cb->state), mode_to_string(md_res.mode));
    switch(md_res.mode)
    {
    case BTM_PM_MD_ACTIVE:
        switch(p_cb->state)
        {
        case BTM_PM_MD_SNIFF:
            btsnd_hcic_exit_sniff_mode(btm_cb.acl_db[link_ind].hci_handle);
            btm_cb.pm_pend_link = link_ind;
            break;
        case BTM_PM_MD_PARK:
            btsnd_hcic_exit_park_mode(btm_cb.acl_db[link_ind].hci_handle);
            btm_cb.pm_pend_link = link_ind;
            break;
        default:
            /* Failure btm_cb.pm_pend_link = MAX_L2CAP_LINKS */
            break;
        }
        break;

    case BTM_PM_MD_HOLD:
        btsnd_hcic_hold_mode(btm_cb.acl_db[link_ind].hci_handle,
                             md_res.max, md_res.min);
        btm_cb.pm_pend_link = link_ind;
        break;

    case BTM_PM_MD_SNIFF:
        btsnd_hcic_sniff_mode(btm_cb.acl_db[link_ind].hci_handle,
                              md_res.max, md_res.min, md_res.attempt,
                              md_res.timeout);
        btm_cb.pm_pend_link = link_ind;
        break;

    case BTM_PM_MD_PARK:
        btsnd_hcic_park_mode(btm_cb.acl_db[link_ind].hci_handle,
                             md_res.max, md_res.min);
        btm_cb.pm_pend_link = link_ind;
        break;
    default:
        /* Failure btm_cb.pm_pend_link = MAX_L2CAP_LINKS */
        break;
    }

    if(btm_cb.pm_pend_link == MAX_L2CAP_LINKS)
    {
        /* the command was not sent */
#if (BTM_PM_DEBUG == TRUE)
        BTM_TRACE_DEBUG( "pm_pend_link: %d",btm_cb.pm_pend_link);
#endif  // BTM_PM_DEBUG
        return (BTM_NO_RESOURCES);
    }

    return BTM_CMD_STARTED;
}

/*******************************************************************************
 *
 * Function         btm_pm_check_stored
 *
 * Description      This function is called when an HCI command status event occurs
 *                  to check if there's any PM command issued while waiting for
 *                  HCI command status.
 *
 * Returns          none.
 *
 ******************************************************************************/
static void btm_pm_check_stored(void)
{
    int     xx;
    for(xx=0; xx<MAX_L2CAP_LINKS; xx++)
    {
        if(btm_cb.pm_mode_db[xx].state & BTM_PM_STORED_MASK)
        {
            btm_cb.pm_mode_db[xx].state &= ~BTM_PM_STORED_MASK;
            BTM_TRACE_DEBUG( "btm_pm_check_stored :%d", xx);
            btm_pm_snd_md_req(BTM_PM_SET_ONLY_ID, xx, NULL);
            break;
        }
    }
}

/*******************************************************************************
 *
 * Function         btm_pm_proc_cmd_status
 *
 * Description      This function is called when an HCI command status event occurs
 *                  for power manager related commands.
 *
 * Input Parms      status - status of the event (HCI_SUCCESS if no errors)
 *
 * Returns          none.
 *
 ******************************************************************************/
void btm_pm_proc_cmd_status(uint8_t status)
{
    tBTM_PM_MCB     *p_cb;
    tBTM_PM_STATUS  pm_status;

    if(btm_cb.pm_pend_link >= MAX_L2CAP_LINKS)
        return;

    p_cb = &btm_cb.pm_mode_db[btm_cb.pm_pend_link];

    if(status == HCI_SUCCESS)
    {
        p_cb->state = BTM_PM_ST_PENDING;
        pm_status = BTM_PM_STS_PENDING;
#if (BTM_PM_DEBUG == TRUE)
        BTM_TRACE_DEBUG( "btm_pm_proc_cmd_status new state:0x%x", p_cb->state);
#endif // BTM_PM_DEBUG
    }
    else /* the command was not successfull. Stay in the same state */
    {
        pm_status = BTM_PM_STS_ERROR;
    }

    /* notify the caller is appropriate */
    if( (btm_cb.pm_pend_id != BTM_PM_SET_ONLY_ID) &&
        (btm_cb.pm_reg_db[btm_cb.pm_pend_id].mask & BTM_PM_REG_NOTIF) )
    {
        (*btm_cb.pm_reg_db[btm_cb.pm_pend_id].cback)(btm_cb.acl_db[btm_cb.pm_pend_link].remote_addr, pm_status, 0, status);
    }

    /* no pending cmd now */
#if (BTM_PM_DEBUG == TRUE)
    BTM_TRACE_DEBUG( "btm_pm_proc_cmd_status state:0x%x, pm_pend_link: %d(new: %d)",
        p_cb->state, btm_cb.pm_pend_link, MAX_L2CAP_LINKS);
#endif  // BTM_PM_DEBUG
    btm_cb.pm_pend_link = MAX_L2CAP_LINKS;

    btm_pm_check_stored();
}

/*******************************************************************************
 *
 * Function         btm_process_mode_change
 *
 * Description      This function is called when an HCI mode change event occurs.
 *
 * Input Parms      hci_status - status of the event (HCI_SUCCESS if no errors)
 *                  hci_handle - connection handle associated with the change
 *                  mode - HCI_MODE_ACTIVE, HCI_MODE_HOLD, HCI_MODE_SNIFF, or HCI_MODE_PARK
 *                  interval - number of baseband slots (meaning depends on mode)
 *
 * Returns          none.
 *
 ******************************************************************************/
void btm_pm_proc_mode_change (uint8_t hci_status, uint16_t hci_handle, uint8_t mode, uint16_t interval)
{
    tACL_CONN   *p;
    tBTM_PM_MCB *p_cb = NULL;
    int xx, yy, zz;
    tBTM_PM_STATE  old_state;
    tL2C_LCB        *p_lcb;

    /* get the index to acl_db */
    xx = btm_handle_to_acl_index(hci_handle);
    if (xx >= MAX_L2CAP_LINKS)
        return;

    p = &btm_cb.acl_db[xx];

    /* update control block */
    p_cb = &(btm_cb.pm_mode_db[xx]);
    old_state       = p_cb->state;
    p_cb->state     = mode;
    p_cb->interval  = interval;

    BTM_TRACE_DEBUG("%s switched from %s to %s.", __func__,
                    mode_to_string(old_state), mode_to_string(p_cb->state));

    p_lcb = l2cu_find_lcb_by_bd_addr(p->remote_addr, BT_TRANSPORT_BR_EDR);
    if (p_lcb != NULL)
    {
        if ((p_cb->state == BTM_PM_ST_ACTIVE) || (p_cb->state == BTM_PM_ST_SNIFF))
        {
            /* There might be any pending packets due to SNIFF or PENDING state */
            /* Trigger L2C to start transmission of the pending packets. */
            BTM_TRACE_DEBUG("btm mode change to active; check l2c_link for outgoing packets");
            l2c_link_check_send_pkts(p_lcb, NULL, NULL);
        }
    }

    /* notify registered parties */
    for(yy=0; yy<=BTM_MAX_PM_RECORDS; yy++)
    {
        /* set req_mode  HOLD mode->ACTIVE */
        if( (mode == BTM_PM_MD_ACTIVE) && (p_cb->req_mode[yy].mode == BTM_PM_MD_HOLD) )
            p_cb->req_mode[yy].mode = BTM_PM_MD_ACTIVE;
    }

    /* new request has been made. - post a message to BTU task */
    if(old_state & BTM_PM_STORED_MASK)
    {
#if (BTM_PM_DEBUG == TRUE)
        BTM_TRACE_DEBUG( "btm_pm_proc_mode_change: Sending stored req:%d", xx);
#endif  // BTM_PM_DEBUG
        btm_pm_snd_md_req(BTM_PM_SET_ONLY_ID, xx, NULL);
    }
    else
    {
        for(zz=0; zz<MAX_L2CAP_LINKS; zz++)
        {
            if(btm_cb.pm_mode_db[zz].chg_ind == true)
            {
#if (BTM_PM_DEBUG == TRUE)
                BTM_TRACE_DEBUG( "btm_pm_proc_mode_change: Sending PM req :%d", zz);
#endif   // BTM_PM_DEBUG
                btm_pm_snd_md_req(BTM_PM_SET_ONLY_ID, zz, NULL);
                break;
            }
        }
    }

    /* notify registered parties */
    for(yy=0; yy<BTM_MAX_PM_RECORDS; yy++)
    {
        if(btm_cb.pm_reg_db[yy].mask & BTM_PM_REG_NOTIF)
        {
            (*btm_cb.pm_reg_db[yy].cback)( p->remote_addr, mode, interval, hci_status);
        }
    }
#if (BTM_SCO_INCLUDED == TRUE)
    /*check if sco disconnect  is waiting for the mode change */
    btm_sco_disc_chk_pend_for_modechange(hci_handle);
#endif

    /* If mode change was because of an active role switch or change link key */
    btm_cont_rswitch(p, btm_find_dev(p->remote_addr), hci_status);
}

/*******************************************************************************
 *
 * Function         btm_pm_proc_ssr_evt
 *
 * Description      This function is called when an HCI sniff subrating event occurs.
 *
 * Returns          none.
 *
 ******************************************************************************/
#if (BTM_SSR_INCLUDED == TRUE)
void btm_pm_proc_ssr_evt (uint8_t *p,
                          UNUSED_ATTR uint16_t evt_len)
{
    uint8_t     status;
    uint16_t    handle;
    uint16_t    max_rx_lat;
    int         xx, yy;
    tBTM_PM_MCB *p_cb;
    tACL_CONN   *p_acl=NULL;
    uint16_t    use_ssr = true;

    STREAM_TO_UINT8 (status, p);

    STREAM_TO_UINT16 (handle, p);
    /* get the index to acl_db */
    xx = btm_handle_to_acl_index(handle);
    if (xx >= MAX_L2CAP_LINKS)
        return;

    p += 2;
    STREAM_TO_UINT16 (max_rx_lat, p);
    p_cb = &(btm_cb.pm_mode_db[xx]);

    p_acl = &btm_cb.acl_db[xx];
    if(p_cb->interval == max_rx_lat)
    {
        /* using legacy sniff */
        use_ssr = false;
    }

    /* notify registered parties */
    for(yy=0; yy<BTM_MAX_PM_RECORDS; yy++)
    {
        if(btm_cb.pm_reg_db[yy].mask & BTM_PM_REG_NOTIF)
        {
            if( p_acl)
            {
                (*btm_cb.pm_reg_db[yy].cback)( p_acl->remote_addr, BTM_PM_STS_SSR, use_ssr, status);
            }
        }
    }
}
#endif  // BTM_SSR_INCLUDED

/*******************************************************************************
 *
 * Function         btm_pm_device_in_active_or_sniff_mode
 *
 * Description      This function is called to check if in active or sniff mode
 *
 * Returns          true, if in active or sniff mode
 *
 ******************************************************************************/
bool    btm_pm_device_in_active_or_sniff_mode(void)
{
    /* The active state is the highest state-includes connected device and sniff mode*/

    /* Covers active and sniff modes */
    if (BTM_GetNumAclLinks() > 0)
    {
        BTM_TRACE_DEBUG("%s - ACL links: %d", __func__, BTM_GetNumAclLinks());
        return true;
    }

    /* Check BLE states */
    if (btm_ble_get_conn_st() != BLE_CONN_IDLE)
    {
        BTM_TRACE_DEBUG("%s - BLE state: %x", __func__, btm_ble_get_conn_st());
        return true;
    }

    return false;
}

/*******************************************************************************
 *
 * Function         btm_pm_device_in_scan_state
 *
 * Description      This function is called to check if in paging, inquiry or connecting mode
 *
 * Returns          true, if in paging, inquiry or connecting mode
 *
 ******************************************************************************/
bool    btm_pm_device_in_scan_state(void)
{
    /* Scan state-paging, inquiry, and trying to connect */

    /* Check for paging */
    if (btm_cb.is_paging || (!fixed_queue_is_empty(btm_cb.page_queue)) ||
       BTM_BL_PAGING_STARTED == btm_cb.busy_level)
    {
       BTM_TRACE_DEBUG("btm_pm_device_in_scan_state- paging");
       return true;
    }

    /* Check for inquiry */
    if ((btm_cb.btm_inq_vars.inq_active & (BTM_BR_INQ_ACTIVE_MASK | BTM_BLE_INQ_ACTIVE_MASK)) != 0)
    {
        BTM_TRACE_DEBUG("btm_pm_device_in_scan_state- Inq active");
        return true;
    }

    return false;
}

/*******************************************************************************
 *
 * Function         BTM_PM_ReadControllerState
 *
 * Description      This function is called to obtain the controller state
 *
 * Returns          Controller State-BTM_CONTRL_ACTIVE, BTM_CONTRL_SCAN, and BTM_CONTRL_IDLE
 *
 ******************************************************************************/
tBTM_CONTRL_STATE BTM_PM_ReadControllerState(void)
{
    if (true == btm_pm_device_in_active_or_sniff_mode())
       return BTM_CONTRL_ACTIVE;
    else
    if (true == btm_pm_device_in_scan_state())
       return BTM_CONTRL_SCAN;
    else
       return BTM_CONTRL_IDLE;
}

static const char *mode_to_string(tBTM_PM_MODE mode) {
  switch (mode) {
    case BTM_PM_MD_ACTIVE: return "ACTIVE";
    case BTM_PM_MD_SNIFF:  return "SNIFF";
    case BTM_PM_MD_PARK:   return "PARK";
    case BTM_PM_MD_HOLD:   return "HOLD";
    default:               return "UNKNOWN";
  }
}