qos.c

讲述linux的初始化过程

/*********************************************************************
 *                                
 * Filename:      qos.c
 * Version:       1.0
 * Description:   IrLAP QoS parameter negotiation
 * Status:        Stable
 * Author:        Dag Brattli <[e-mail]>
 * Created at:    Tue Sep  9 00:00:26 1997
 * Modified at:   Sun Jan 30 14:29:16 2000
 * Modified by:   Dag Brattli <[e-mail]>
 * 
 *     Copyright (c) 1998-2000 Dag Brattli <[e-mail]>, 
 *     All Rights Reserved.
 *     
 *     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/config.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>
#ifdef CONFIG_IRDA_COMPRESSION
#include <net/irda/irlap_comp.h>
#include "../../drivers/net/zlib.h"

#define CI_BZIP2  27 /* Random pick */
#endif

/*
 * Maximum values of the baud rate we negociate 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 negociate with the other end.
 * Most often, the value below represent the best compromise, but some user
 * may want to keep the LAP alive longuer or shorter in case of link failure.
 * Remember that the threshold time (early warning) is fixed to 3s...
 */
int sysctl_max_inactive_time = 12;

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);
static int value_index(__u32 value, __u32 *array, int size);
static __u32 byte_value(__u8 byte, __u32 *array);
static __u32 index_value(int index, __u32 *array);
static int value_lower_bits(__u32 value, __u32 *array, int size, __u16 *field);

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

#ifdef CONFIG_IRDA_COMPRESSION
__u32 compressions[] = { CI_BZIP2, CI_DEFLATE, CI_DEFLATE_DRAFT };
#endif

__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 };

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

#ifdef CONFIG_IRDA_COMPRESSION
	qos->compression.bits     &= new->compression.bits;
#endif

	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_inactive_time, link_disc_times, 8,
			     &qos->link_disc_time.bits);
	sysctl_max_inactive_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;

#ifdef CONFIG_IRDA_COMPRESSION	
	qos->compression.bits     = 0x03;
#endif
}

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

	IRDA_DEBUG(2, __FUNCTION__ "()\n");

	/* 
	 * 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, __FUNCTION__ 
			   "(), adjusting max turn time from %d to 500 ms\n",
			   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, __FUNCTION__ 
			   "(), redusing data size to %d\n",
			   qos->data_size.value);
	}
#else /* Use method descibed in section 6.6.11 of IrLAP */
	while (irlap_requested_line_capacity(qos) > line_capacity) {
		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, __FUNCTION__ 
				   "(), redusing window size to %d\n",
				   qos->window_size.value);
		} else if (index > 1) {
			qos->data_size.value = data_sizes[index--];
			IRDA_DEBUG(2, __FUNCTION__ 
				   "(), redusing data size to %d\n",
				   qos->data_size.value);
		} else {
			WARNING(__FUNCTION__ "(), nothing more we can do!\n");
		}
	}
#endif CONFIG_IRDA_DYNAMIC_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;
#ifdef CONFIG_IRDA_COMPRESSION
	int comp_seen = FALSE;
#endif
	ret = irda_param_extract_all(self, skb->data, skb->len, 
				     &irlap_param_info);
	
#ifdef CONFIG_IRDA_COMPRESSION
	if (!comp_seen) {
		IRDA_DEBUG( 4, __FUNCTION__ "(), Compression not seen!\n");
		self->qos_tx.compression.bits = 0x00;
		self->qos_rx.compression.bits = 0x00;
	}
#endif

	/* 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);
#ifdef CONFIG_IRDA_COMPRESSION
	IRDA_DEBUG(2, "Setting COMPRESSION to %d\n", 
		   self->qos_tx.compression.value);
#endif	
	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, 
				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, 
				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, 
				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, 
				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, 
				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, 
				skb_tailroom(skb), &irlap_param_info);
	if (ret < 0)