qos.c

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/*********************************************************************
 *
 * Filename:      qos.c
 * Version:       1.0
 * Description:   IrLAP QoS parameter negotiation
 * Status:        Stable
 * Author:        Dag Brattli <[email protected]>
 * Created at:    Tue Sep  9 00:00:26 1997
 * Modified at:   Sun Jan 30 14:29:16 2000
 * Modified by:   Dag Brattli <[email protected]>
 *
 *     Copyright (c) 1998-2000 Dag Brattli <[email protected]>,
 *     All Rights Reserved.
 *     Copyright (c) 2000-2001 Jean Tourrilhes <[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 <linux/export.h>

#include <asm/byteorder.h>

#include <net/irda/irda.h>
#include <net/irda/parameters.h>
#include <net/irda/qos.h>
#include <net/irda/irlap.h>
#include <net/irda/irlap_frame.h>

/*
 * Maximum values of the baud rate we negotiate with the other end.
 * Most often, you don't have to change that, because Linux-IrDA will
 * use the maximum offered by the link layer, which usually works fine.
 * In some very rare cases, you may want to limit it to lower speeds...
 */
int sysctl_max_baud_rate = 16000000;
/*
 * Maximum value of the lap disconnect timer we negotiate with the other end.
 * Most often, the value below represent the best compromise, but some user
 * may want to keep the LAP alive longer or shorter in case of link failure.
 * Remember that the threshold time (early warning) is fixed to 3s...
 */
int sysctl_max_noreply_time = 12;
/*
 * Minimum turn time to be applied before transmitting to the peer.
 * Nonzero values (usec) are used as lower limit to the per-connection
 * mtt value which was announced by the other end during negotiation.
 * Might be helpful if the peer device provides too short mtt.
 * Default is 10us which means using the unmodified value given by the
 * peer except if it's 0 (0 is likely a bug in the other stack).
 */
unsigned int sysctl_min_tx_turn_time = 10;
/*
 * Maximum data size to be used in transmission in payload of LAP frame.
 * There is a bit of confusion in the IrDA spec :
 * The LAP spec defines the payload of a LAP frame (I field) to be
 * 2048 bytes max (IrLAP 1.1, chapt 6.6.5, p40).
 * On the other hand, the PHY mention frames of 2048 bytes max (IrPHY
 * 1.2, chapt 5.3.2.1, p41). But, this number includes the LAP header
 * (2 bytes), and CRC (32 bits at 4 Mb/s). So, for the I field (LAP
 * payload), that's only 2042 bytes. Oups !
 * My nsc-ircc hardware has troubles receiving 2048 bytes frames at 4 Mb/s,
 * so adjust to 2042... I don't know if this bug applies only for 2048
 * bytes frames or all negotiated frame sizes, but you can use the sysctl
 * to play with this value anyway.
 * Jean II */
unsigned int sysctl_max_tx_data_size = 2042;
/*
 * Maximum transmit window, i.e. number of LAP frames between turn-around.
 * This allow to override what the peer told us. Some peers are buggy and
 * don't always support what they tell us.
 * Jean II */
unsigned int sysctl_max_tx_window = 7;

static int irlap_param_baud_rate(void *instance, irda_param_t *param, int get);
static int irlap_param_link_disconnect(void *instance, irda_param_t *parm,
                       int get);
static int irlap_param_max_turn_time(void *instance, irda_param_t *param,
                     int get);
static int irlap_param_data_size(void *instance, irda_param_t *param, int get);
static int irlap_param_window_size(void *instance, irda_param_t *param,
                   int get);
static int irlap_param_additional_bofs(void *instance, irda_param_t *parm,
                       int get);
static int irlap_param_min_turn_time(void *instance, irda_param_t *param,
                     int get);

#ifndef CONFIG_IRDA_DYNAMIC_WINDOW
static __u32 irlap_requested_line_capacity(struct qos_info *qos);
#endif

static __u32 min_turn_times[]  = { 10000, 5000, 1000, 500, 100, 50, 10, 0 }; /* us */
static __u32 baud_rates[]      = { 2400, 9600, 19200, 38400, 57600, 115200, 576000,
                   1152000, 4000000, 16000000 };           /* bps */
static __u32 data_sizes[]      = { 64, 128, 256, 512, 1024, 2048 };        /* bytes */
static __u32 add_bofs[]        = { 48, 24, 12, 5, 3, 2, 1, 0 };            /* bytes */
static __u32 max_turn_times[]  = { 500, 250, 100, 50 };                    /* ms */
static __u32 link_disc_times[] = { 3, 8, 12, 16, 20, 25, 30, 40 };         /* secs */

static __u32 max_line_capacities[10][4] = {
       /* 500 ms     250 ms  100 ms  50 ms (max turn time) */
    {    100,      0,      0,     0 }, /*     2400 bps */
    {    400,      0,      0,     0 }, /*     9600 bps */
    {    800,      0,      0,     0 }, /*    19200 bps */
    {   1600,      0,      0,     0 }, /*    38400 bps */
    {   2360,      0,      0,     0 }, /*    57600 bps */
    {   4800,   2400,    960,   480 }, /*   115200 bps */
    {  28800,  11520,   5760,  2880 }, /*   576000 bps */
    {  57600,  28800,  11520,  5760 }, /*  1152000 bps */
    { 200000, 100000,  40000, 20000 }, /*  4000000 bps */
    { 800000, 400000, 160000, 80000 }, /* 16000000 bps */
};

static pi_minor_info_t pi_minor_call_table_type_0[] = {
    { NULL, 0 },
/* 01 */{ irlap_param_baud_rate,       PV_INTEGER | PV_LITTLE_ENDIAN },
    { NULL, 0 },
    { NULL, 0 },
    { NULL, 0 },
    { NULL, 0 },
    { NULL, 0 },
    { NULL, 0 },
/* 08 */{ irlap_param_link_disconnect, PV_INT_8_BITS }
};

static pi_minor_info_t pi_minor_call_table_type_1[] = {
    { NULL, 0 },
    { NULL, 0 },
/* 82 */{ irlap_param_max_turn_time,   PV_INT_8_BITS },
/* 83 */{ irlap_param_data_size,       PV_INT_8_BITS },
/* 84 */{ irlap_param_window_size,     PV_INT_8_BITS },
/* 85 */{ irlap_param_additional_bofs, PV_INT_8_BITS },
/* 86 */{ irlap_param_min_turn_time,   PV_INT_8_BITS },
};

static pi_major_info_t pi_major_call_table[] = {
    { pi_minor_call_table_type_0, 9 },
    { pi_minor_call_table_type_1, 7 },
};

static pi_param_info_t irlap_param_info = { pi_major_call_table, 2, 0x7f, 7 };

/* ---------------------- LOCAL SUBROUTINES ---------------------- */
/* Note : we start with a bunch of local subroutines.
 * As the compiler is "one pass", this is the only way to get them to
 * inline properly...
 * Jean II
 */
/*
 * Function value_index (value, array, size)
 *
 *    Returns the index to the value in the specified array
 */
static inline int value_index(__u32 value, __u32 *array, int size)
{
    int i;

    for (i=0; i < size; i++)
        if (array[i] == value)
            break;
    return i;
}

/*
 * Function index_value (index, array)
 *
 *    Returns value to index in array, easy!
 *
 */
static inline __u32 index_value(int index, __u32 *array)
{
    return array[index];
}

/*
 * Function msb_index (word)
 *
 *    Returns index to most significant bit (MSB) in word
 *
 */
static int msb_index (__u16 word)
{
    __u16 msb = 0x8000;
    int index = 15;   /* Current MSB */

    /* Check for buggy peers.
     * Note : there is a small probability that it could be us, but I
     * would expect driver authors to catch that pretty early and be
     * able to check precisely what's going on. If a end user sees this,
     * it's very likely the peer. - Jean II */
    if (word == 0) {
        IRDA_WARNING("%s(), Detected buggy peer, adjust null PV to 0x1!\n",
             __func__);
        /* The only safe choice (we don't know the array size) */
        word = 0x1;
    }

    while (msb) {
        if (word & msb)
            break;   /* Found it! */
        msb >>=1;
        index--;
    }
    return index;
}

/*
 * Function value_lower_bits (value, array)
 *
 *    Returns a bit field marking all possibility lower than value.
 */
static inline int value_lower_bits(__u32 value, __u32 *array, int size, __u16 *field)
{
    int i;
    __u16   mask = 0x1;
    __u16   result = 0x0;

    for (i=0; i < size; i++) {
        /* Add the current value to the bit field, shift mask */
        result |= mask;
        mask <<= 1;
        /* Finished ? */
        if (array[i] >= value)
            break;
    }
    /* Send back a valid index */
    if(i >= size)
      i = size - 1; /* Last item */
    *field = result;
    return i;
}

/*
 * Function value_highest_bit (value, array)
 *
 *    Returns a bit field marking the highest possibility lower than value.
 */
static inline int value_highest_bit(__u32 value, __u32 *array, int size, __u16 *field)
{
    int i;
    __u16   mask = 0x1;
    __u16   result = 0x0;

    for (i=0; i < size; i++) {
        /* Finished ? */
        if (array[i] <= value)
            break;
        /* Shift mask */
        mask <<= 1;
    }
    /* Set the current value to the bit field */
    result |= mask;
    /* Send back a valid index */
    if(i >= size)
      i = size - 1; /* Last item */
    *field = result;
    return i;
}

/* -------------------------- MAIN CALLS -------------------------- */

/*
 * Function irda_qos_compute_intersection (qos, new)
 *
 *    Compute the intersection of the old QoS capabilities with new ones
 *
 */
void irda_qos_compute_intersection(struct qos_info *qos, struct qos_info *new)
{
    IRDA_ASSERT(qos != NULL, return;);
    IRDA_ASSERT(new != NULL, return;);

    /* Apply */
    qos->baud_rate.bits       &= new->baud_rate.bits;
    qos->window_size.bits     &= new->window_size.bits;
    qos->min_turn_time.bits   &= new->min_turn_time.bits;
    qos->max_turn_time.bits   &= new->max_turn_time.bits;
    qos->data_size.bits       &= new->data_size.bits;
    qos->link_disc_time.bits  &= new->link_disc_time.bits;
    qos->additional_bofs.bits &= new->additional_bofs.bits;

    irda_qos_bits_to_value(qos);
}

/*
 * Function irda_init_max_qos_capabilies (qos)
 *
 *    The purpose of this function is for layers and drivers to be able to
 *    set the maximum QoS possible and then "and in" their own limitations
 *
 */
void irda_init_max_qos_capabilies(struct qos_info *qos)
{
    int i;
    /*
     *  These are the maximum supported values as specified on pages
     *  39-43 in IrLAP
     */

    /* Use sysctl to set some configurable values... */
    /* Set configured max speed */
    i = value_lower_bits(sysctl_max_baud_rate, baud_rates, 10,
                 &qos->baud_rate.bits);
    sysctl_max_baud_rate = index_value(i, baud_rates);

    /* Set configured max disc time */
    i = value_lower_bits(sysctl_max_noreply_time, link_disc_times, 8,
                 &qos->link_disc_time.bits);
    sysctl_max_noreply_time = index_value(i, link_disc_times);

    /* LSB is first byte, MSB is second byte */
    qos->baud_rate.bits    &= 0x03ff;

    qos->window_size.bits     = 0x7f;
    qos->min_turn_time.bits   = 0xff;
    qos->max_turn_time.bits   = 0x0f;
    qos->data_size.bits       = 0x3f;
    qos->link_disc_time.bits &= 0xff;
    qos->additional_bofs.bits = 0xff;
}
EXPORT_SYMBOL(irda_init_max_qos_capabilies);

/*
 * Function irlap_adjust_qos_settings (qos)
 *
 *     Adjust QoS settings in case some values are not possible to use because
 *     of other settings
 */
static void irlap_adjust_qos_settings(struct qos_info *qos)
{
    __u32 line_capacity;
    int index;

    IRDA_DEBUG(2, "%s()\n", __func__);

    /*
     * Make sure the mintt is sensible.
     * Main culprit : Ericsson T39. - Jean II
     */
    if (sysctl_min_tx_turn_time > qos->min_turn_time.value) {
        int i;

        IRDA_WARNING("%s(), Detected buggy peer, adjust mtt to %dus!\n",
             __func__, sysctl_min_tx_turn_time);

        /* We don't really need bits, but easier this way */
        i = value_highest_bit(sysctl_min_tx_turn_time, min_turn_times,
                      8, &qos->min_turn_time.bits);
        sysctl_min_tx_turn_time = index_value(i, min_turn_times);
        qos->min_turn_time.value = sysctl_min_tx_turn_time;
    }

    /*
     * Not allowed to use a max turn time less than 500 ms if the baudrate
     * is less than 115200
     */
    if ((qos->baud_rate.value < 115200) &&
        (qos->max_turn_time.value < 500))
    {
        IRDA_DEBUG(0,
               "%s(), adjusting max turn time from %d to 500 ms\n",
               __func__, qos->max_turn_time.value);
        qos->max_turn_time.value = 500;
    }

    /*
     * The data size must be adjusted according to the baud rate and max
     * turn time
     */
    index = value_index(qos->data_size.value, data_sizes, 6);
    line_capacity = irlap_max_line_capacity(qos->baud_rate.value,
                        qos->max_turn_time.value);

#ifdef CONFIG_IRDA_DYNAMIC_WINDOW
    while ((qos->data_size.value > line_capacity) && (index > 0)) {
        qos->data_size.value = data_sizes[index--];
        IRDA_DEBUG(2, "%s(), reducing data size to %d\n",
               __func__, qos->data_size.value);
    }
#else /* Use method described in section 6.6.11 of IrLAP */
    while (irlap_requested_line_capacity(qos) > line_capacity) {
        IRDA_ASSERT(index != 0, return;);

        /* Must be able to send at least one frame */
        if (qos->window_size.value > 1) {
            qos->window_size.value--;
            IRDA_DEBUG(2, "%s(), reducing window size to %d\n",
                   __func__, qos->window_size.value);
        } else if (index > 1) {
            qos->data_size.value = data_sizes[index--];
            IRDA_DEBUG(2, "%s(), reducing data size to %d\n",
                   __func__, qos->data_size.value);
        } else {
            IRDA_WARNING("%s(), nothing more we can do!\n",
                     __func__);
        }
    }
#endif /* CONFIG_IRDA_DYNAMIC_WINDOW */
    /*
     * Fix tx data size according to user limits - Jean II
     */
    if (qos->data_size.value > sysctl_max_tx_data_size)
        /* Allow non discrete adjustement to avoid losing capacity */
        qos->data_size.value = sysctl_max_tx_data_size;
    /*
     * Override Tx window if user request it. - Jean II
     */
    if (qos->window_size.value > sysctl_max_tx_window)
        qos->window_size.value = sysctl_max_tx_window;
}

/*
 * Function irlap_negotiate (qos_device, qos_session, skb)
 *
 *    Negotiate QoS values, not really that much negotiation :-)
 *    We just set the QoS capabilities for the peer station
 *
 */
int irlap_qos_negotiate(struct irlap_cb *self, struct sk_buff *skb)
{
    int ret;

    ret = irda_param_extract_all(self, skb->data, skb->len,
                     &irlap_param_info);

    /* Convert the negotiated bits to values */
    irda_qos_bits_to_value(&self->qos_tx);
    irda_qos_bits_to_value(&self->qos_rx);

    irlap_adjust_qos_settings(&self->qos_tx);

    IRDA_DEBUG(2, "Setting BAUD_RATE to %d bps.\n",
           self->qos_tx.baud_rate.value);
    IRDA_DEBUG(2, "Setting DATA_SIZE to %d bytes\n",
           self->qos_tx.data_size.value);
    IRDA_DEBUG(2, "Setting WINDOW_SIZE to %d\n",
           self->qos_tx.window_size.value);
    IRDA_DEBUG(2, "Setting XBOFS to %d\n",
           self->qos_tx.additional_bofs.value);
    IRDA_DEBUG(2, "Setting MAX_TURN_TIME to %d ms.\n",
           self->qos_tx.max_turn_time.value);
    IRDA_DEBUG(2, "Setting MIN_TURN_TIME to %d usecs.\n",
           self->qos_tx.min_turn_time.value);
    IRDA_DEBUG(2, "Setting LINK_DISC to %d secs.\n",
           self->qos_tx.link_disc_time.value);
    return ret;
}

/*
 * Function irlap_insert_negotiation_params (qos, fp)
 *
 *    Insert QoS negotiaion pararameters into frame
 *
 */
int irlap_insert_qos_negotiation_params(struct irlap_cb *self,
                    struct sk_buff *skb)
{
    int ret;

    /* Insert data rate */
    ret = irda_param_insert(self, PI_BAUD_RATE, skb_tail_pointer(skb),
                skb_tailroom(skb), &irlap_param_info);
    if (ret < 0)
        return ret;
    skb_put(skb, ret);

    /* Insert max turnaround time */
    ret = irda_param_insert(self, PI_MAX_TURN_TIME, skb_tail_pointer(skb),
                skb_tailroom(skb), &irlap_param_info);
    if (ret < 0)
        return ret;
    skb_put(skb, ret);

    /* Insert data size */
    ret = irda_param_insert(self, PI_DATA_SIZE, skb_tail_pointer(skb),
                skb_tailroom(skb), &irlap_param_info);
    if (ret < 0)
        return ret;
    skb_put(skb, ret);

    /* Insert window size */
    ret = irda_param_insert(self, PI_WINDOW_SIZE, skb_tail_pointer(skb),
                skb_tailroom(skb), &irlap_param_info);
    if (ret < 0)
        return ret;
    skb_put(skb, ret);

    /* Insert additional BOFs */
    ret = irda_param_insert(self, PI_ADD_BOFS, skb_tail_pointer(skb),
                skb_tailroom(skb), &irlap_param_info);
    if (ret < 0)
        return ret;
    skb_put(skb, ret);

    /* Insert minimum turnaround time */
    ret = irda_param_insert(self, PI_MIN_TURN_TIME, skb_tail_pointer(skb),
                skb_tailroom(skb), &irlap_param_info);
    if (ret < 0)
        return ret;
    skb_put(skb, ret);

    /* Insert link disconnect/threshold time */
    ret = irda_param_insert(self, PI_LINK_DISC, skb_tail_pointer(skb),
                skb_tailroom(skb), &irlap_param_info);
    if (ret < 0)
        return ret;
    skb_put(skb, ret);

    return 0;
}

/*
 * Function irlap_param_baud_rate (instance, param, get)
 *
 *    Negotiate data-rate
 *
 */
static int irlap_param_baud_rate(void *instance, irda_param_t *param, int get)
{
    __u16 final;

    struct irlap_cb *self = (struct irlap_cb *) instance;

    IRDA_ASSERT(self != NULL, return -1;);
    IRDA_ASSERT(self->magic == LAP_MAGIC, return -1;);

    if (get) {
        param->pv.i = self->qos_rx.baud_rate.bits;
        IRDA_DEBUG(2, "%s(), baud rate = 0x%02x\n",
               __func__, param->pv.i);
    } else {
        /*
         *  Stations must agree on baud rate, so calculate
         *  intersection
         */
        IRDA_DEBUG(2, "Requested BAUD_RATE: 0x%04x\n", (__u16) param->pv.i);
        final = (__u16) param->pv.i & self->qos_rx.baud_rate.bits;

        IRDA_DEBUG(2, "Final BAUD_RATE: 0x%04x\n", final);
        self->qos_tx.baud_rate.bits = final;
        self->qos_rx.baud_rate.bits = final;
    }

    return 0;
}

/*
 * Function irlap_param_link_disconnect (instance, param, get)
 *
 *    Negotiate link disconnect/threshold time.
 *
 */
static int irlap_param_link_disconnect(void *instance, irda_param_t *param,
                       int get)
{
    __u16 final;

    struct irlap_cb *self = (struct irlap_cb *) instance;

    IRDA_ASSERT(self != NULL, return -1;);
    IRDA_ASSERT(self->magic == LAP_MAGIC, return -1;);

    if (get)
        param->pv.i = self->qos_rx.link_disc_time.bits;
    else {
        /*
         *  Stations must agree on link disconnect/threshold
         *  time.
         */
        IRDA_DEBUG(2, "LINK_DISC: %02x\n", (__u8) param->pv.i);
        final = (__u8) param->pv.i & self->qos_rx.link_disc_time.bits;

        IRDA_DEBUG(2, "Final LINK_DISC: %02x\n", final);
        self->qos_tx.link_disc_time.bits = final;
        self->qos_rx.link_disc_time.bits = final;
    }
    return 0;
}

/*
 * Function irlap_param_max_turn_time (instance, param, get)
 *
 *    Negotiate the maximum turnaround time. This is a type 1 parameter and
 *    will be negotiated independently for each station
 *
 */
static int irlap_param_max_turn_time(void *instance, irda_param_t *param,
                     int get)
{
    struct irlap_cb *self = (struct irlap_cb *) instance;

    IRDA_ASSERT(self != NULL, return -1;);
    IRDA_ASSERT(self->magic == LAP_MAGIC, return -1;);

    if (get)
        param->pv.i = self->qos_rx.max_turn_time.bits;
    else
        self->qos_tx.max_turn_time.bits = (__u8) param->pv.i;

    return 0;
}

/*
 * Function irlap_param_data_size (instance, param, get)
 *
 *    Negotiate the data size. This is a type 1 parameter and
 *    will be negotiated independently for each station
 *
 */
static int irlap_param_data_size(void *instance, irda_param_t *param, int get)
{
    struct irlap_cb *self = (struct irlap_cb *) instance;

    IRDA_ASSERT(self != NULL, return -1;);
    IRDA_ASSERT(self->magic == LAP_MAGIC, return -1;);

    if (get)
        param->pv.i = self->qos_rx.data_size.bits;
    else
        self->qos_tx.data_size.bits = (__u8) param->pv.i;

    return 0;
}

/*
 * Function irlap_param_window_size (instance, param, get)
 *
 *    Negotiate the window size. This is a type 1 parameter and
 *    will be negotiated independently for each station
 *
 */
static int irlap_param_window_size(void *instance, irda_param_t *param,
                   int get)
{
    struct irlap_cb *self = (struct irlap_cb *) instance;

    IRDA_ASSERT(self != NULL, return -1;);
    IRDA_ASSERT(self->magic == LAP_MAGIC, return -1;);

    if (get)
        param->pv.i = self->qos_rx.window_size.bits;
    else
        self->qos_tx.window_size.bits = (__u8) param->pv.i;

    return 0;
}

/*
 * Function irlap_param_additional_bofs (instance, param, get)
 *
 *    Negotiate additional BOF characters. This is a type 1 parameter and
 *    will be negotiated independently for each station.
 */
static int irlap_param_additional_bofs(void *instance, irda_param_t *param, int get)
{
    struct irlap_cb *self = (struct irlap_cb *) instance;

    IRDA_ASSERT(self != NULL, return -1;);
    IRDA_ASSERT(self->magic == LAP_MAGIC, return -1;);

    if (get)
        param->pv.i = self->qos_rx.additional_bofs.bits;
    else
        self->qos_tx.additional_bofs.bits = (__u8) param->pv.i;

    return 0;
}

/*
 * Function irlap_param_min_turn_time (instance, param, get)
 *
 *    Negotiate the minimum turn around time. This is a type 1 parameter and
 *    will be negotiated independently for each station
 */
static int irlap_param_min_turn_time(void *instance, irda_param_t *param,
                     int get)
{
    struct irlap_cb *self = (struct irlap_cb *) instance;

    IRDA_ASSERT(self != NULL, return -1;);
    IRDA_ASSERT(self->magic == LAP_MAGIC, return -1;);

    if (get)
        param->pv.i = self->qos_rx.min_turn_time.bits;
    else
        self->qos_tx.min_turn_time.bits = (__u8) param->pv.i;

    return 0;
}

/*
 * Function irlap_max_line_capacity (speed, max_turn_time, min_turn_time)
 *
 *    Calculate the maximum line capacity
 *
 */
__u32 irlap_max_line_capacity(__u32 speed, __u32 max_turn_time)
{
    __u32 line_capacity;
    int i,j;

    IRDA_DEBUG(2, "%s(), speed=%d, max_turn_time=%d\n",
           __func__, speed, max_turn_time);

    i = value_index(speed, baud_rates, 10);
    j = value_index(max_turn_time, max_turn_times, 4);

    IRDA_ASSERT(((i >=0) && (i <10)), return 0;);
    IRDA_ASSERT(((j >=0) && (j <4)), return 0;);

    line_capacity = max_line_capacities[i][j];

    IRDA_DEBUG(2, "%s(), line capacity=%d bytes\n",
           __func__, line_capacity);

    return line_capacity;
}

#ifndef CONFIG_IRDA_DYNAMIC_WINDOW
static __u32 irlap_requested_line_capacity(struct qos_info *qos)
{
    __u32 line_capacity;

    line_capacity = qos->window_size.value *
        (qos->data_size.value + 6 + qos->additional_bofs.value) +
        irlap_min_turn_time_in_bytes(qos->baud_rate.value,
                         qos->min_turn_time.value);

    IRDA_DEBUG(2, "%s(), requested line capacity=%d\n",
           __func__, line_capacity);

    return line_capacity;
}
#endif

void irda_qos_bits_to_value(struct qos_info *qos)
{
    int index;

    IRDA_ASSERT(qos != NULL, return;);

    index = msb_index(qos->baud_rate.bits);
    qos->baud_rate.value = baud_rates[index];

    index = msb_index(qos->data_size.bits);
    qos->data_size.value = data_sizes[index];

    index = msb_index(qos->window_size.bits);
    qos->window_size.value = index+1;

    index = msb_index(qos->min_turn_time.bits);
    qos->min_turn_time.value = min_turn_times[index];

    index = msb_index(qos->max_turn_time.bits);
    qos->max_turn_time.value = max_turn_times[index];

    index = msb_index(qos->link_disc_time.bits);
    qos->link_disc_time.value = link_disc_times[index];

    index = msb_index(qos->additional_bofs.bits);
    qos->additional_bofs.value = add_bofs[index];
}
EXPORT_SYMBOL(irda_qos_bits_to_value);