qos.c

讲述linux的初始化过程

		return ret;
	skb_put(skb, ret);

	/* Insert link disconnect/threshold time */
	ret = irda_param_insert(self, PI_LINK_DISC, skb->tail, 
				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;

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

	if (get) {
		param->pv.i = self->qos_rx.baud_rate.bits;
		IRDA_DEBUG(2, __FUNCTION__ "(), baud rate = 0x%02x\n", 
			   param->pv.i);		
	} else {
		/* 
		 *  Stations must agree on baud rate, so calculate
		 *  intersection 
		 */
		IRDA_DEBUG(2, "Requested BAUD_RATE: 0x%04x\n", param->pv.s);
		final = param->pv.s & 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;
	
	ASSERT(self != NULL, return -1;);
	ASSERT(self->magic == LAP_MAGIC, return -1;);
	
	if (get)
		param->pv.b = self->qos_rx.link_disc_time.bits;
	else {
		/*  
		 *  Stations must agree on link disconnect/threshold 
		 *  time.
		 */
		IRDA_DEBUG(2, "LINK_DISC: %02x\n", param->pv.b);
		final = param->pv.b & 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;
	
	ASSERT(self != NULL, return -1;);
	ASSERT(self->magic == LAP_MAGIC, return -1;);
	
	if (get)
		param->pv.b = self->qos_rx.max_turn_time.bits;
	else
		self->qos_tx.max_turn_time.bits = param->pv.b;

	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;
	
	ASSERT(self != NULL, return -1;);
	ASSERT(self->magic == LAP_MAGIC, return -1;);
	
	if (get)
		param->pv.b = self->qos_rx.data_size.bits;
	else
		self->qos_tx.data_size.bits = param->pv.b;

	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;
	
	ASSERT(self != NULL, return -1;);
	ASSERT(self->magic == LAP_MAGIC, return -1;);
	
	if (get)
		param->pv.b = self->qos_rx.window_size.bits;
	else
		self->qos_tx.window_size.bits = param->pv.b;

	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;
	
	ASSERT(self != NULL, return -1;);
	ASSERT(self->magic == LAP_MAGIC, return -1;);
	
	if (get)
		param->pv.b = self->qos_rx.additional_bofs.bits;
	else
		self->qos_tx.additional_bofs.bits = param->pv.b;

	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;
	
	ASSERT(self != NULL, return -1;);
	ASSERT(self->magic == LAP_MAGIC, return -1;);
	
	if (get)
		param->pv.b = self->qos_rx.min_turn_time.bits;
	else
		self->qos_tx.min_turn_time.bits = param->pv.b;

	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, __FUNCTION__ "(), speed=%d, max_turn_time=%d\n",
		   speed, max_turn_time);

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

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

	line_capacity = max_line_capacities[i][j];

	IRDA_DEBUG(2, __FUNCTION__ "(), line capacity=%d bytes\n", 
		   line_capacity);
	
	return line_capacity;
}

__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, __FUNCTION__ "(), requested line capacity=%d\n",
		   line_capacity);
	
	return line_capacity;			       		  
}

__u32 irlap_min_turn_time_in_bytes(__u32 speed, __u32 min_turn_time)
{
	__u32 bytes;
	
	bytes = speed * min_turn_time / 10000000;
	
	return bytes;
}

static __u32 byte_value(__u8 byte, __u32 *array) 
{
	int index;

	ASSERT(array != NULL, return -1;);

	index = msb_index(byte);

	return index_value(index, array);
}

/*
 * Function msb_index (word)
 *
 *    Returns index to most significant bit (MSB) in word
 *
 */
int msb_index (__u16 word) 
{
	__u16 msb = 0x8000;
	int index = 15;   /* Current MSB */
	
	while (msb) {
		if (word & msb)
			break;   /* Found it! */
		msb >>=1;
		index--;
	}
	return index;
}

/*
 * Function value_index (value, array, size)
 *
 *    Returns the index to the value in the specified array
 */
static 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 __u32 index_value(int index, __u32 *array) 
{
	return array[index];
}

/*
 * Function value_lower_bits (value, array)
 *
 *    Returns a bit field marking all possibility lower than value.
 *    We may need a "value_higher_bits" in the future...
 */
static 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;
}

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

	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];

#ifdef CONFIG_IRDA_COMPRESSION
	index = msb_index(qos->compression.bits);
	if (index >= 0)
		qos->compression.value = compressions[index];
	else 
		qos->compression.value = 0;
#endif
}