xref: /drivers/staging/ozwpan/ozpd.c

/* -----------------------------------------------------------------------------
 * Copyright (c) 2011 Ozmo Inc
 * Released under the GNU General Public License Version 2 (GPLv2).
 * -----------------------------------------------------------------------------
 */

#include <linux/module.h>
#include <linux/timer.h>
#include <linux/sched.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/errno.h>
#include "ozdbg.h"
#include "ozprotocol.h"
#include "ozeltbuf.h"
#include "ozpd.h"
#include "ozproto.h"
#include "ozcdev.h"
#include "ozusbsvc.h"
#include <asm/unaligned.h>
#include <linux/uaccess.h>
#include <net/psnap.h>

static struct oz_tx_frame *oz_tx_frame_alloc(struct oz_pd *pd);
static void oz_tx_frame_free(struct oz_pd *pd, struct oz_tx_frame *f);
static void oz_tx_isoc_free(struct oz_pd *pd, struct oz_tx_frame *f);
static struct sk_buff *oz_build_frame(struct oz_pd *pd, struct oz_tx_frame *f);
static int oz_send_isoc_frame(struct oz_pd *pd);
static void oz_retire_frame(struct oz_pd *pd, struct oz_tx_frame *f);
static void oz_isoc_stream_free(struct oz_isoc_stream *st);
static int oz_send_next_queued_frame(struct oz_pd *pd, int more_data);
static void oz_isoc_destructor(struct sk_buff *skb);

/*
 * Counts the uncompleted isoc frames submitted to netcard.
 */
static atomic_t g_submitted_isoc = ATOMIC_INIT(0);

/* Application handler functions.
 */
static const struct oz_app_if g_app_if[OZ_NB_APPS] = {
	[OZ_APPID_USB] = {
		.init      = oz_usb_init,
		.term      = oz_usb_term,
		.start     = oz_usb_start,
		.stop      = oz_usb_stop,
		.rx        = oz_usb_rx,
		.heartbeat = oz_usb_heartbeat,
		.farewell  = oz_usb_farewell,
	},
	[OZ_APPID_SERIAL] = {
		.init      = oz_cdev_init,
		.term      = oz_cdev_term,
		.start     = oz_cdev_start,
		.stop      = oz_cdev_stop,
		.rx        = oz_cdev_rx,
	},
};


/*
 * Context: softirq or process
 */
void oz_pd_set_state(struct oz_pd *pd, unsigned state)
{
	pd->state = state;
	switch (state) {
	case OZ_PD_S_IDLE:
		oz_pd_dbg(pd, ON, "PD State: OZ_PD_S_IDLE\n");
		break;
	case OZ_PD_S_CONNECTED:
		oz_pd_dbg(pd, ON, "PD State: OZ_PD_S_CONNECTED\n");
		break;
	case OZ_PD_S_STOPPED:
		oz_pd_dbg(pd, ON, "PD State: OZ_PD_S_STOPPED\n");
		break;
	case OZ_PD_S_SLEEP:
		oz_pd_dbg(pd, ON, "PD State: OZ_PD_S_SLEEP\n");
		break;
	}
}

/*
 * Context: softirq or process
 */
void oz_pd_get(struct oz_pd *pd)
{
	atomic_inc(&pd->ref_count);
}

/*
 * Context: softirq or process
 */
void oz_pd_put(struct oz_pd *pd)
{
	if (atomic_dec_and_test(&pd->ref_count))
		oz_pd_destroy(pd);
}

/*
 * Context: softirq-serialized
 */
struct oz_pd *oz_pd_alloc(const u8 *mac_addr)
{
	struct oz_pd *pd = kzalloc(sizeof(struct oz_pd), GFP_ATOMIC);

	if (pd) {
		int i;
		atomic_set(&pd->ref_count, 2);
		for (i = 0; i < OZ_NB_APPS; i++)
			spin_lock_init(&pd->app_lock[i]);
		pd->last_rx_pkt_num = 0xffffffff;
		oz_pd_set_state(pd, OZ_PD_S_IDLE);
		pd->max_tx_size = OZ_MAX_TX_SIZE;
		ether_addr_copy(pd->mac_addr, mac_addr);
		oz_elt_buf_init(&pd->elt_buff);
		spin_lock_init(&pd->tx_frame_lock);
		INIT_LIST_HEAD(&pd->tx_queue);
		INIT_LIST_HEAD(&pd->farewell_list);
		pd->last_sent_frame = &pd->tx_queue;
		spin_lock_init(&pd->stream_lock);
		INIT_LIST_HEAD(&pd->stream_list);
		tasklet_init(&pd->heartbeat_tasklet, oz_pd_heartbeat_handler,
							(unsigned long)pd);
		tasklet_init(&pd->timeout_tasklet, oz_pd_timeout_handler,
							(unsigned long)pd);
		hrtimer_init(&pd->heartbeat, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
		hrtimer_init(&pd->timeout, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
		pd->heartbeat.function = oz_pd_heartbeat_event;
		pd->timeout.function = oz_pd_timeout_event;
	}
	return pd;
}

/*
 * Context: softirq or process
 */
static void oz_pd_free(struct work_struct *work)
{
	struct list_head *e;
	struct oz_tx_frame *f;
	struct oz_isoc_stream *st;
	struct oz_farewell *fwell;
	struct oz_pd *pd;

	oz_pd_dbg(pd, ON, "Destroying PD\n");
	pd = container_of(work, struct oz_pd, workitem);
	/*Disable timer tasklets*/
	tasklet_kill(&pd->heartbeat_tasklet);
	tasklet_kill(&pd->timeout_tasklet);
	/* Delete any streams.
	 */
	e = pd->stream_list.next;
	while (e != &pd->stream_list) {
		st = container_of(e, struct oz_isoc_stream, link);
		e = e->next;
		oz_isoc_stream_free(st);
	}
	/* Free any queued tx frames.
	 */
	e = pd->tx_queue.next;
	while (e != &pd->tx_queue) {
		f = container_of(e, struct oz_tx_frame, link);
		e = e->next;
		if (f->skb != NULL)
			kfree_skb(f->skb);
		oz_retire_frame(pd, f);
	}
	oz_elt_buf_term(&pd->elt_buff);
	/* Free any farewells.
	 */
	e = pd->farewell_list.next;
	while (e != &pd->farewell_list) {
		fwell = container_of(e, struct oz_farewell, link);
		e = e->next;
		kfree(fwell);
	}
	if (pd->net_dev)
		dev_put(pd->net_dev);
	kfree(pd);
}

/*
 * Context: softirq or Process
 */
void oz_pd_destroy(struct oz_pd *pd)
{
	if (hrtimer_active(&pd->timeout))
		hrtimer_cancel(&pd->timeout);
	if (hrtimer_active(&pd->heartbeat))
		hrtimer_cancel(&pd->heartbeat);

	INIT_WORK(&pd->workitem, oz_pd_free);
	if (!schedule_work(&pd->workitem))
		oz_pd_dbg(pd, ON, "failed to schedule workitem\n");
}

/*
 * Context: softirq-serialized
 */
int oz_services_start(struct oz_pd *pd, u16 apps, int resume)
{
	int i, rc = 0;

	oz_pd_dbg(pd, ON, "%s: (0x%x) resume(%d)\n", __func__, apps, resume);
	for (i = 0; i < OZ_NB_APPS; i++) {
		if (g_app_if[i].start && (apps & (1 << i))) {
			if (g_app_if[i].start(pd, resume)) {
				rc = -1;
				oz_pd_dbg(pd, ON,
					  "Unable to start service %d\n", i);
				break;
			}
			spin_lock_bh(&g_polling_lock);
			pd->total_apps |= (1 << i);
			if (resume)
				pd->paused_apps &= ~(1 << i);
			spin_unlock_bh(&g_polling_lock);
		}
	}
	return rc;
}

/*
 * Context: softirq or process
 */
void oz_services_stop(struct oz_pd *pd, u16 apps, int pause)
{
	int i;

	oz_pd_dbg(pd, ON, "%s: (0x%x) pause(%d)\n", __func__, apps, pause);
	for (i = 0; i < OZ_NB_APPS; i++) {
		if (g_app_if[i].stop && (apps & (1 << i))) {
			spin_lock_bh(&g_polling_lock);
			if (pause) {
				pd->paused_apps |=  (1 << i);
			} else {
				pd->total_apps  &= ~(1 << i);
				pd->paused_apps &= ~(1 << i);
			}
			spin_unlock_bh(&g_polling_lock);
			g_app_if[i].stop(pd, pause);
		}
	}
}

/*
 * Context: softirq
 */
void oz_pd_heartbeat(struct oz_pd *pd, u16 apps)
{
	int i, more = 0;

	for (i = 0; i < OZ_NB_APPS; i++) {
		if (g_app_if[i].heartbeat && (apps & (1 << i))) {
			if (g_app_if[i].heartbeat(pd))
				more = 1;
		}
	}
	if ((!more) && (hrtimer_active(&pd->heartbeat)))
		hrtimer_cancel(&pd->heartbeat);
	if (pd->mode & OZ_F_ISOC_ANYTIME) {
		int count = 8;
		while (count-- && (oz_send_isoc_frame(pd) >= 0))
			;
	}
}

/*
 * Context: softirq or process
 */
void oz_pd_stop(struct oz_pd *pd)
{
	u16 stop_apps;

	oz_dbg(ON, "oz_pd_stop() State = 0x%x\n", pd->state);
	oz_pd_indicate_farewells(pd);
	spin_lock_bh(&g_polling_lock);
	stop_apps = pd->total_apps;
	pd->total_apps = 0;
	pd->paused_apps = 0;
	spin_unlock_bh(&g_polling_lock);
	oz_services_stop(pd, stop_apps, 0);
	spin_lock_bh(&g_polling_lock);
	oz_pd_set_state(pd, OZ_PD_S_STOPPED);
	/* Remove from PD list.*/
	list_del(&pd->link);
	spin_unlock_bh(&g_polling_lock);
	oz_dbg(ON, "pd ref count = %d\n", atomic_read(&pd->ref_count));
	oz_pd_put(pd);
}

/*
 * Context: softirq
 */
int oz_pd_sleep(struct oz_pd *pd)
{
	int do_stop = 0;
	u16 stop_apps;

	spin_lock_bh(&g_polling_lock);
	if (pd->state & (OZ_PD_S_SLEEP | OZ_PD_S_STOPPED)) {
		spin_unlock_bh(&g_polling_lock);
		return 0;
	}
	if (pd->keep_alive && pd->session_id)
		oz_pd_set_state(pd, OZ_PD_S_SLEEP);
	else
		do_stop = 1;

	stop_apps = pd->total_apps;
	spin_unlock_bh(&g_polling_lock);
	if (do_stop) {
		oz_pd_stop(pd);
	} else {
		oz_services_stop(pd, stop_apps, 1);
		oz_timer_add(pd, OZ_TIMER_STOP, pd->keep_alive);
	}
	return do_stop;
}

/*
 * Context: softirq
 */
static struct oz_tx_frame *oz_tx_frame_alloc(struct oz_pd *pd)
{
	struct oz_tx_frame *f;

	f = kmem_cache_alloc(oz_tx_frame_cache, GFP_ATOMIC);
	if (f) {
		f->total_size = sizeof(struct oz_hdr);
		INIT_LIST_HEAD(&f->link);
		INIT_LIST_HEAD(&f->elt_list);
	}
	return f;
}

/*
 * Context: softirq or process
 */
static void oz_tx_isoc_free(struct oz_pd *pd, struct oz_tx_frame *f)
{
	pd->nb_queued_isoc_frames--;
	list_del_init(&f->link);

	kmem_cache_free(oz_tx_frame_cache, f);

	oz_dbg(TX_FRAMES, "Releasing ISOC Frame isoc_nb= %d\n",
	       pd->nb_queued_isoc_frames);
}

/*
 * Context: softirq or process
 */
static void oz_tx_frame_free(struct oz_pd *pd, struct oz_tx_frame *f)
{
	kmem_cache_free(oz_tx_frame_cache, f);
}

/*
 * Context: softirq-serialized
 */
static void oz_set_more_bit(struct sk_buff *skb)
{
	struct oz_hdr *oz_hdr = (struct oz_hdr *)skb_network_header(skb);

	oz_hdr->control |= OZ_F_MORE_DATA;
}

/*
 * Context: softirq-serialized
 */
static void oz_set_last_pkt_nb(struct oz_pd *pd, struct sk_buff *skb)
{
	struct oz_hdr *oz_hdr = (struct oz_hdr *)skb_network_header(skb);

	oz_hdr->last_pkt_num = pd->trigger_pkt_num & OZ_LAST_PN_MASK;
}

/*
 * Context: softirq
 */
int oz_prepare_frame(struct oz_pd *pd, int empty)
{
	struct oz_tx_frame *f;

	if ((pd->mode & OZ_MODE_MASK) != OZ_MODE_TRIGGERED)
		return -1;
	if (pd->nb_queued_frames >= OZ_MAX_QUEUED_FRAMES)
		return -1;
	if (!empty && !oz_are_elts_available(&pd->elt_buff))
		return -1;
	f = oz_tx_frame_alloc(pd);
	if (f == NULL)
		return -1;
	f->skb = NULL;
	f->hdr.control =
		(OZ_PROTOCOL_VERSION<<OZ_VERSION_SHIFT) | OZ_F_ACK_REQUESTED;
	++pd->last_tx_pkt_num;
	put_unaligned(cpu_to_le32(pd->last_tx_pkt_num), &f->hdr.pkt_num);
	if (empty == 0) {
		oz_select_elts_for_tx(&pd->elt_buff, 0, &f->total_size,
			pd->max_tx_size, &f->elt_list);
	}
	spin_lock(&pd->tx_frame_lock);
	list_add_tail(&f->link, &pd->tx_queue);
	pd->nb_queued_frames++;
	spin_unlock(&pd->tx_frame_lock);
	return 0;
}

/*
 * Context: softirq-serialized
 */
static struct sk_buff *oz_build_frame(struct oz_pd *pd, struct oz_tx_frame *f)
{
	struct sk_buff *skb;
	struct net_device *dev = pd->net_dev;
	struct oz_hdr *oz_hdr;
	struct oz_elt *elt;
	struct list_head *e;

	/* Allocate skb with enough space for the lower layers as well
	 * as the space we need.
	 */
	skb = alloc_skb(f->total_size + OZ_ALLOCATED_SPACE(dev), GFP_ATOMIC);
	if (skb == NULL)
		return NULL;
	/* Reserve the head room for lower layers.
	 */
	skb_reserve(skb, LL_RESERVED_SPACE(dev));
	skb_reset_network_header(skb);
	skb->dev = dev;
	skb->protocol = htons(OZ_ETHERTYPE);
	if (dev_hard_header(skb, dev, OZ_ETHERTYPE, pd->mac_addr,
		dev->dev_addr, skb->len) < 0)
		goto fail;
	/* Push the tail to the end of the area we are going to copy to.
	 */
	oz_hdr = (struct oz_hdr *)skb_put(skb, f->total_size);
	f->hdr.last_pkt_num = pd->trigger_pkt_num & OZ_LAST_PN_MASK;
	memcpy(oz_hdr, &f->hdr, sizeof(struct oz_hdr));
	/* Copy the elements into the frame body.
	 */
	elt = (struct oz_elt *)(oz_hdr+1);
	for (e = f->elt_list.next; e != &f->elt_list; e = e->next) {
		struct oz_elt_info *ei;
		ei = container_of(e, struct oz_elt_info, link);
		memcpy(elt, ei->data, ei->length);
		elt = oz_next_elt(elt);
	}
	return skb;
fail:
	kfree_skb(skb);
	return NULL;
}

/*
 * Context: softirq or process
 */
static void oz_retire_frame(struct oz_pd *pd, struct oz_tx_frame *f)
{
	struct list_head *e;
	struct oz_elt_info *ei;

	e = f->elt_list.next;
	while (e != &f->elt_list) {
		ei = container_of(e, struct oz_elt_info, link);
		e = e->next;
		list_del_init(&ei->link);
		if (ei->callback)
			ei->callback(pd, ei->context);
		spin_lock_bh(&pd->elt_buff.lock);
		oz_elt_info_free(&pd->elt_buff, ei);
		spin_unlock_bh(&pd->elt_buff.lock);
	}
	oz_tx_frame_free(pd, f);
}

/*
 * Context: softirq-serialized
 */
static int oz_send_next_queued_frame(struct oz_pd *pd, int more_data)
{
	struct sk_buff *skb;
	struct oz_tx_frame *f;
	struct list_head *e;

	spin_lock(&pd->tx_frame_lock);
	e = pd->last_sent_frame->next;
	if (e == &pd->tx_queue) {
		spin_unlock(&pd->tx_frame_lock);
		return -1;
	}
	f = container_of(e, struct oz_tx_frame, link);

	if (f->skb != NULL) {
		skb = f->skb;
		oz_tx_isoc_free(pd, f);
		spin_unlock(&pd->tx_frame_lock);
		if (more_data)
			oz_set_more_bit(skb);
		oz_set_last_pkt_nb(pd, skb);
		if ((int)atomic_read(&g_submitted_isoc) <
							OZ_MAX_SUBMITTED_ISOC) {
			if (dev_queue_xmit(skb) < 0) {
				oz_dbg(TX_FRAMES, "Dropping ISOC Frame\n");
				return -1;
			}
			atomic_inc(&g_submitted_isoc);
			oz_dbg(TX_FRAMES, "Sending ISOC Frame, nb_isoc= %d\n",
			       pd->nb_queued_isoc_frames);
			return 0;
		} else {
			kfree_skb(skb);
			oz_dbg(TX_FRAMES, "Dropping ISOC Frame>\n");
			return -1;
		}
	}

	pd->last_sent_frame = e;
	skb = oz_build_frame(pd, f);
	spin_unlock(&pd->tx_frame_lock);
	if (!skb)
		return -1;
	if (more_data)
		oz_set_more_bit(skb);
	oz_dbg(TX_FRAMES, "TX frame PN=0x%x\n", f->hdr.pkt_num);
	if (dev_queue_xmit(skb) < 0)
		return -1;

	return 0;
}

/*
 * Context: softirq-serialized
 */
void oz_send_queued_frames(struct oz_pd *pd, int backlog)
{
	while (oz_prepare_frame(pd, 0) >= 0)
		backlog++;

	switch (pd->mode & (OZ_F_ISOC_NO_ELTS | OZ_F_ISOC_ANYTIME)) {

		case OZ_F_ISOC_NO_ELTS: {
			backlog += pd->nb_queued_isoc_frames;
			if (backlog <= 0)
				goto out;
			if (backlog > OZ_MAX_SUBMITTED_ISOC)
				backlog = OZ_MAX_SUBMITTED_ISOC;
			break;
		}
		case OZ_NO_ELTS_ANYTIME: {
			if ((backlog <= 0) && (pd->isoc_sent == 0))
				goto out;
			break;
		}
		default: {
			if (backlog <= 0)
				goto out;
			break;
		}
	}
	while (backlog--) {
		if (oz_send_next_queued_frame(pd, backlog) < 0)
			break;
	}
	return;

out:	oz_prepare_frame(pd, 1);
	oz_send_next_queued_frame(pd, 0);
}

/*
 * Context: softirq
 */
static int oz_send_isoc_frame(struct oz_pd *pd)
{
	struct sk_buff *skb;
	struct net_device *dev = pd->net_dev;
	struct oz_hdr *oz_hdr;
	struct oz_elt *elt;
	struct list_head *e;
	struct list_head list;
	int total_size = sizeof(struct oz_hdr);

	INIT_LIST_HEAD(&list);

	oz_select_elts_for_tx(&pd->elt_buff, 1, &total_size,
		pd->max_tx_size, &list);
	if (list.next == &list)
		return 0;
	skb = alloc_skb(total_size + OZ_ALLOCATED_SPACE(dev), GFP_ATOMIC);
	if (skb == NULL) {
		oz_dbg(ON, "Cannot alloc skb\n");
		oz_elt_info_free_chain(&pd->elt_buff, &list);
		return -1;
	}
	skb_reserve(skb, LL_RESERVED_SPACE(dev));
	skb_reset_network_header(skb);
	skb->dev = dev;
	skb->protocol = htons(OZ_ETHERTYPE);
	if (dev_hard_header(skb, dev, OZ_ETHERTYPE, pd->mac_addr,
		dev->dev_addr, skb->len) < 0) {
		kfree_skb(skb);
		return -1;
	}
	oz_hdr = (struct oz_hdr *)skb_put(skb, total_size);
	oz_hdr->control = (OZ_PROTOCOL_VERSION<<OZ_VERSION_SHIFT) | OZ_F_ISOC;
	oz_hdr->last_pkt_num = pd->trigger_pkt_num & OZ_LAST_PN_MASK;
	elt = (struct oz_elt *)(oz_hdr+1);

	for (e = list.next; e != &list; e = e->next) {
		struct oz_elt_info *ei;
		ei = container_of(e, struct oz_elt_info, link);
		memcpy(elt, ei->data, ei->length);
		elt = oz_next_elt(elt);
	}
	dev_queue_xmit(skb);
	oz_elt_info_free_chain(&pd->elt_buff, &list);
	return 0;
}

/*
 * Context: softirq-serialized
 */
void oz_retire_tx_frames(struct oz_pd *pd, u8 lpn)
{
	struct list_head *e;
	struct oz_tx_frame *f;
	struct list_head *first = NULL;
	struct list_head *last = NULL;
	u8 diff;
	u32 pkt_num;

	spin_lock(&pd->tx_frame_lock);
	e = pd->tx_queue.next;
	while (e != &pd->tx_queue) {
		f = container_of(e, struct oz_tx_frame, link);
		pkt_num = le32_to_cpu(get_unaligned(&f->hdr.pkt_num));
		diff = (lpn - (pkt_num & OZ_LAST_PN_MASK)) & OZ_LAST_PN_MASK;
		if ((diff > OZ_LAST_PN_HALF_CYCLE) || (pkt_num == 0))
			break;
		oz_dbg(TX_FRAMES, "Releasing pkt_num= %u, nb= %d\n",
		       pkt_num, pd->nb_queued_frames);
		if (first == NULL)
			first = e;
		last = e;
		e = e->next;
		pd->nb_queued_frames--;
	}
	if (first) {
		last->next->prev = &pd->tx_queue;
		pd->tx_queue.next = last->next;
		last->next = NULL;
	}
	pd->last_sent_frame = &pd->tx_queue;
	spin_unlock(&pd->tx_frame_lock);
	while (first) {
		f = container_of(first, struct oz_tx_frame, link);
		first = first->next;
		oz_retire_frame(pd, f);
	}
}

/*
 * Precondition: stream_lock must be held.
 * Context: softirq
 */
static struct oz_isoc_stream *pd_stream_find(struct oz_pd *pd, u8 ep_num)
{
	struct list_head *e;
	struct oz_isoc_stream *st;

	list_for_each(e, &pd->stream_list) {
		st = container_of(e, struct oz_isoc_stream, link);
		if (st->ep_num == ep_num)
			return st;
	}
	return NULL;
}

/*
 * Context: softirq
 */
int oz_isoc_stream_create(struct oz_pd *pd, u8 ep_num)
{
	struct oz_isoc_stream *st =
		kzalloc(sizeof(struct oz_isoc_stream), GFP_ATOMIC);
	if (!st)
		return -ENOMEM;
	st->ep_num = ep_num;
	spin_lock_bh(&pd->stream_lock);
	if (!pd_stream_find(pd, ep_num)) {
		list_add(&st->link, &pd->stream_list);
		st = NULL;
	}
	spin_unlock_bh(&pd->stream_lock);
	kfree(st);
	return 0;
}

/*
 * Context: softirq or process
 */
static void oz_isoc_stream_free(struct oz_isoc_stream *st)
{
	kfree_skb(st->skb);
	kfree(st);
}

/*
 * Context: softirq
 */
int oz_isoc_stream_delete(struct oz_pd *pd, u8 ep_num)
{
	struct oz_isoc_stream *st;

	spin_lock_bh(&pd->stream_lock);
	st = pd_stream_find(pd, ep_num);
	if (st)
		list_del(&st->link);
	spin_unlock_bh(&pd->stream_lock);
	if (st)
		oz_isoc_stream_free(st);
	return 0;
}

/*
 * Context: any
 */
static void oz_isoc_destructor(struct sk_buff *skb)
{
	atomic_dec(&g_submitted_isoc);
}

/*
 * Context: softirq
 */
int oz_send_isoc_unit(struct oz_pd *pd, u8 ep_num, const u8 *data, int len)
{
	struct net_device *dev = pd->net_dev;
	struct oz_isoc_stream *st;
	u8 nb_units = 0;
	struct sk_buff *skb = NULL;
	struct oz_hdr *oz_hdr = NULL;
	int size = 0;

	spin_lock_bh(&pd->stream_lock);
	st = pd_stream_find(pd, ep_num);
	if (st) {
		skb = st->skb;
		st->skb = NULL;
		nb_units = st->nb_units;
		st->nb_units = 0;
		oz_hdr = st->oz_hdr;
		size = st->size;
	}
	spin_unlock_bh(&pd->stream_lock);
	if (!st)
		return 0;
	if (!skb) {
		/* Allocate enough space for max size frame. */
		skb = alloc_skb(pd->max_tx_size + OZ_ALLOCATED_SPACE(dev),
				GFP_ATOMIC);
		if (skb == NULL)
			return 0;
		/* Reserve the head room for lower layers. */
		skb_reserve(skb, LL_RESERVED_SPACE(dev));
		skb_reset_network_header(skb);
		skb->dev = dev;
		skb->protocol = htons(OZ_ETHERTYPE);
		/* For audio packet set priority to AC_VO */
		skb->priority = 0x7;
		size = sizeof(struct oz_hdr) + sizeof(struct oz_isoc_large);
		oz_hdr = (struct oz_hdr *)skb_put(skb, size);
	}
	memcpy(skb_put(skb, len), data, len);
	size += len;
	if (++nb_units < pd->ms_per_isoc) {
		spin_lock_bh(&pd->stream_lock);
		st->skb = skb;
		st->nb_units = nb_units;
		st->oz_hdr = oz_hdr;
		st->size = size;
		spin_unlock_bh(&pd->stream_lock);
	} else {
		struct oz_hdr oz;
		struct oz_isoc_large iso;
		spin_lock_bh(&pd->stream_lock);
		iso.frame_number = st->frame_num;
		st->frame_num += nb_units;
		spin_unlock_bh(&pd->stream_lock);
		oz.control =
			(OZ_PROTOCOL_VERSION<<OZ_VERSION_SHIFT) | OZ_F_ISOC;
		oz.last_pkt_num = pd->trigger_pkt_num & OZ_LAST_PN_MASK;
		oz.pkt_num = 0;
		iso.endpoint = ep_num;
		iso.format = OZ_DATA_F_ISOC_LARGE;
		iso.ms_data = nb_units;
		memcpy(oz_hdr, &oz, sizeof(oz));
		memcpy(oz_hdr+1, &iso, sizeof(iso));
		if (dev_hard_header(skb, dev, OZ_ETHERTYPE, pd->mac_addr,
				dev->dev_addr, skb->len) < 0)
			goto out;

		skb->destructor = oz_isoc_destructor;
		/*Queue for Xmit if mode is not ANYTIME*/
		if (!(pd->mode & OZ_F_ISOC_ANYTIME)) {
			struct oz_tx_frame *isoc_unit = NULL;
			int nb = pd->nb_queued_isoc_frames;
			if (nb >= pd->isoc_latency) {
				struct list_head *e;
				struct oz_tx_frame *f;
				oz_dbg(TX_FRAMES, "Dropping ISOC Unit nb= %d\n",
				       nb);
				spin_lock(&pd->tx_frame_lock);
				list_for_each(e, &pd->tx_queue) {
					f = container_of(e, struct oz_tx_frame,
									link);
					if (f->skb != NULL) {
						oz_tx_isoc_free(pd, f);
						break;
					}
				}
				spin_unlock(&pd->tx_frame_lock);
			}
			isoc_unit = oz_tx_frame_alloc(pd);
			if (isoc_unit == NULL)
				goto out;
			isoc_unit->hdr = oz;
			isoc_unit->skb = skb;
			spin_lock_bh(&pd->tx_frame_lock);
			list_add_tail(&isoc_unit->link, &pd->tx_queue);
			pd->nb_queued_isoc_frames++;
			spin_unlock_bh(&pd->tx_frame_lock);
			oz_dbg(TX_FRAMES,
			       "Added ISOC Frame to Tx Queue isoc_nb= %d, nb= %d\n",
			       pd->nb_queued_isoc_frames, pd->nb_queued_frames);
			return 0;
		}

		/*In ANYTIME mode Xmit unit immediately*/
		if (atomic_read(&g_submitted_isoc) < OZ_MAX_SUBMITTED_ISOC) {
			atomic_inc(&g_submitted_isoc);
			if (dev_queue_xmit(skb) < 0)
				return -1;
			else
				return 0;
		}

out:	kfree_skb(skb);
	return -1;

	}
	return 0;
}

/*
 * Context: process
 */
void oz_apps_init(void)
{
	int i;

	for (i = 0; i < OZ_NB_APPS; i++) {
		if (g_app_if[i].init)
			g_app_if[i].init();
	}
}

/*
 * Context: process
 */
void oz_apps_term(void)
{
	int i;

	/* Terminate all the apps. */
	for (i = 0; i < OZ_NB_APPS; i++) {
		if (g_app_if[i].term)
			g_app_if[i].term();
	}
}

/*
 * Context: softirq-serialized
 */
void oz_handle_app_elt(struct oz_pd *pd, u8 app_id, struct oz_elt *elt)
{
	if (app_id < OZ_NB_APPS && g_app_if[app_id].rx)
		g_app_if[app_id].rx(pd, elt);
}

/*
 * Context: softirq or process
 */
void oz_pd_indicate_farewells(struct oz_pd *pd)
{
	struct oz_farewell *f;
	const struct oz_app_if *ai = &g_app_if[OZ_APPID_USB];

	while (1) {
		spin_lock_bh(&g_polling_lock);
		if (list_empty(&pd->farewell_list)) {
			spin_unlock_bh(&g_polling_lock);
			break;
		}
		f = list_first_entry(&pd->farewell_list,
				struct oz_farewell, link);
		list_del(&f->link);
		spin_unlock_bh(&g_polling_lock);
		if (ai->farewell)
			ai->farewell(pd, f->ep_num, f->report, f->len);
		kfree(f);
	}
}