crypto/async_tx/async_tx.c - kernel/common - Git at Google

 /*
  * core routines for the asynchronous memory transfer/transform api
  *
  * Copyright © 2006, Intel Corporation.
  *
  *	Dan Williams <[email protected]>
  *
  *	with architecture considerations by:
  *	Neil Brown <[email protected]>
  *	Jeff Garzik <[email protected]>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
  * version 2, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope 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.,
  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  *
  */
 #include <linux/rculist.h>
 #include <linux/kernel.h>
 #include <linux/async_tx.h>

 #ifdef CONFIG_DMA_ENGINE
 static int __init async_tx_init(void)
 {
 	async_dmaengine_get();

 	printk(KERN_INFO "async_tx: api initialized (async)\n");

 	return 0;
 }

 static void __exit async_tx_exit(void)
 {
 	async_dmaengine_put();
 }

 module_init(async_tx_init);
 module_exit(async_tx_exit);

 /**
  * __async_tx_find_channel - find a channel to carry out the operation or let
  *	the transaction execute synchronously
  * @submit: transaction dependency and submission modifiers
  * @tx_type: transaction type
  */
 struct dma_chan *
 __async_tx_find_channel(struct async_submit_ctl *submit,
 			enum dma_transaction_type tx_type)
 {
 	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;

 	/* see if we can keep the chain on one channel */
 	if (depend_tx &&
 	    dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
 		return depend_tx->chan;
 	return async_dma_find_channel(tx_type);
 }
 EXPORT_SYMBOL_GPL(__async_tx_find_channel);
 #endif


 /**
  * async_tx_channel_switch - queue an interrupt descriptor with a dependency
  * 	pre-attached.
  * @depend_tx: the operation that must finish before the new operation runs
  * @tx: the new operation
  */
 static void
 async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
 			struct dma_async_tx_descriptor *tx)
 {
 	struct dma_chan *chan = depend_tx->chan;
 	struct dma_device *device = chan->device;
 	struct dma_async_tx_descriptor *intr_tx = (void *) ~0;

 	/* first check to see if we can still append to depend_tx */
 	txd_lock(depend_tx);
 	if (txd_parent(depend_tx) && depend_tx->chan == tx->chan) {
 		txd_chain(depend_tx, tx);
 		intr_tx = NULL;
 	}
 	txd_unlock(depend_tx);

 	/* attached dependency, flush the parent channel */
 	if (!intr_tx) {
 		device->device_issue_pending(chan);
 		return;
 	}

 	/* see if we can schedule an interrupt
 	 * otherwise poll for completion
 	 */
 	if (dma_has_cap(DMA_INTERRUPT, device->cap_mask))
 		intr_tx = device->device_prep_dma_interrupt(chan, 0);
 	else
 		intr_tx = NULL;

 	if (intr_tx) {
 		intr_tx->callback = NULL;
 		intr_tx->callback_param = NULL;
 		/* safe to chain outside the lock since we know we are
 		 * not submitted yet
 		 */
 		txd_chain(intr_tx, tx);

 		/* check if we need to append */
 		txd_lock(depend_tx);
 		if (txd_parent(depend_tx)) {
 			txd_chain(depend_tx, intr_tx);
 			async_tx_ack(intr_tx);
 			intr_tx = NULL;
 		}
 		txd_unlock(depend_tx);

 		if (intr_tx) {
 			txd_clear_parent(intr_tx);
 			intr_tx->tx_submit(intr_tx);
 			async_tx_ack(intr_tx);
 		}
 		device->device_issue_pending(chan);
 	} else {
 		if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
 			panic("%s: DMA_ERROR waiting for depend_tx\n",
 			      __func__);
 		tx->tx_submit(tx);
 	}
 }


 /**
  * submit_disposition - flags for routing an incoming operation
  * @ASYNC_TX_SUBMITTED: we were able to append the new operation under the lock
  * @ASYNC_TX_CHANNEL_SWITCH: when the lock is dropped schedule a channel switch
  * @ASYNC_TX_DIRECT_SUBMIT: when the lock is dropped submit directly
  *
  * while holding depend_tx->lock we must avoid submitting new operations
  * to prevent a circular locking dependency with drivers that already
  * hold a channel lock when calling async_tx_run_dependencies.
  */
 enum submit_disposition {
 	ASYNC_TX_SUBMITTED,
 	ASYNC_TX_CHANNEL_SWITCH,
 	ASYNC_TX_DIRECT_SUBMIT,
 };

 void
 async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
 		struct async_submit_ctl *submit)
 {
 	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;

 	tx->callback = submit->cb_fn;
 	tx->callback_param = submit->cb_param;

 	if (depend_tx) {
 		enum submit_disposition s;

 		/* sanity check the dependency chain:
 		 * 1/ if ack is already set then we cannot be sure
 		 * we are referring to the correct operation
 		 * 2/ dependencies are 1:1 i.e. two transactions can
 		 * not depend on the same parent
 		 */
 		BUG_ON(async_tx_test_ack(depend_tx) || txd_next(depend_tx) ||
 		       txd_parent(tx));

 		/* the lock prevents async_tx_run_dependencies from missing
 		 * the setting of ->next when ->parent != NULL
 		 */
 		txd_lock(depend_tx);
 		if (txd_parent(depend_tx)) {
 			/* we have a parent so we can not submit directly
 			 * if we are staying on the same channel: append
 			 * else: channel switch
 			 */
 			if (depend_tx->chan == chan) {
 				txd_chain(depend_tx, tx);
 				s = ASYNC_TX_SUBMITTED;
 			} else
 				s = ASYNC_TX_CHANNEL_SWITCH;
 		} else {
 			/* we do not have a parent so we may be able to submit
 			 * directly if we are staying on the same channel
 			 */
 			if (depend_tx->chan == chan)
 				s = ASYNC_TX_DIRECT_SUBMIT;
 			else
 				s = ASYNC_TX_CHANNEL_SWITCH;
 		}
 		txd_unlock(depend_tx);

 		switch (s) {
 		case ASYNC_TX_SUBMITTED:
 			break;
 		case ASYNC_TX_CHANNEL_SWITCH:
 			async_tx_channel_switch(depend_tx, tx);
 			break;
 		case ASYNC_TX_DIRECT_SUBMIT:
 			txd_clear_parent(tx);
 			tx->tx_submit(tx);
 			break;
 		}
 	} else {
 		txd_clear_parent(tx);
 		tx->tx_submit(tx);
 	}

 	if (submit->flags & ASYNC_TX_ACK)
 		async_tx_ack(tx);

 	if (depend_tx)
 		async_tx_ack(depend_tx);
 }
 EXPORT_SYMBOL_GPL(async_tx_submit);

 /**
  * async_trigger_callback - schedules the callback function to be run
  * @submit: submission and completion parameters
  *
  * honored flags: ASYNC_TX_ACK
  *
  * The callback is run after any dependent operations have completed.
  */
 struct dma_async_tx_descriptor *
 async_trigger_callback(struct async_submit_ctl *submit)
 {
 	struct dma_chan *chan;
 	struct dma_device *device;
 	struct dma_async_tx_descriptor *tx;
 	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;

 	if (depend_tx) {
 		chan = depend_tx->chan;
 		device = chan->device;

 		/* see if we can schedule an interrupt
 		 * otherwise poll for completion
 		 */
 		if (device && !dma_has_cap(DMA_INTERRUPT, device->cap_mask))
 			device = NULL;

 		tx = device ? device->device_prep_dma_interrupt(chan, 0) : NULL;
 	} else
 		tx = NULL;

 	if (tx) {
 		pr_debug("%s: (async)\n", __func__);

 		async_tx_submit(chan, tx, submit);
 	} else {
 		pr_debug("%s: (sync)\n", __func__);

 		/* wait for any prerequisite operations */
 		async_tx_quiesce(&submit->depend_tx);

 		async_tx_sync_epilog(submit);
 	}

 	return tx;
 }
 EXPORT_SYMBOL_GPL(async_trigger_callback);

 /**
  * async_tx_quiesce - ensure tx is complete and freeable upon return
  * @tx - transaction to quiesce
  */
 void async_tx_quiesce(struct dma_async_tx_descriptor **tx)
 {
 	if (*tx) {
 		/* if ack is already set then we cannot be sure
 		 * we are referring to the correct operation
 		 */
 		BUG_ON(async_tx_test_ack(*tx));
 		if (dma_wait_for_async_tx(*tx) == DMA_ERROR)
 			panic("DMA_ERROR waiting for transaction\n");
 		async_tx_ack(*tx);
 		*tx = NULL;
 	}
 }
 EXPORT_SYMBOL_GPL(async_tx_quiesce);

 MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION("Asynchronous Bulk Memory Transactions API");
 MODULE_LICENSE("GPL");
	/*
	* core routines for the asynchronous memory transfer/transform api
	*
	* Copyright © 2006, Intel Corporation.
	*
	* Dan Williams <[email protected]>
	*
	* with architecture considerations by:
	* Neil Brown <[email protected]>
	* Jeff Garzik <[email protected]>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms and conditions of the GNU General Public License,
	* version 2, as published by the Free Software Foundation.
	*
	* This program is distributed in the hope 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.,
	* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
	*
	*/
	#include <linux/rculist.h>
	#include <linux/kernel.h>
	#include <linux/async_tx.h>

	#ifdef CONFIG_DMA_ENGINE
	static int __init async_tx_init(void)
	{
	async_dmaengine_get();

	printk(KERN_INFO "async_tx: api initialized (async)\n");

	return 0;
	}

	static void __exit async_tx_exit(void)
	{
	async_dmaengine_put();
	}

	module_init(async_tx_init);
	module_exit(async_tx_exit);

	/**
	* __async_tx_find_channel - find a channel to carry out the operation or let
	* the transaction execute synchronously
	* @submit: transaction dependency and submission modifiers
	* @tx_type: transaction type
	*/
	struct dma_chan *
	__async_tx_find_channel(struct async_submit_ctl *submit,
	enum dma_transaction_type tx_type)
	{
	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;

	/* see if we can keep the chain on one channel */
	if (depend_tx &&
	dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
	return depend_tx->chan;
	return async_dma_find_channel(tx_type);
	}
	EXPORT_SYMBOL_GPL(__async_tx_find_channel);
	#endif


	/**
	* async_tx_channel_switch - queue an interrupt descriptor with a dependency
	* pre-attached.
	* @depend_tx: the operation that must finish before the new operation runs
	* @tx: the new operation
	*/
	static void
	async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
	struct dma_async_tx_descriptor *tx)
	{
	struct dma_chan *chan = depend_tx->chan;
	struct dma_device *device = chan->device;
	struct dma_async_tx_descriptor intr_tx = (void ) ~0;

	/* first check to see if we can still append to depend_tx */
	txd_lock(depend_tx);
	if (txd_parent(depend_tx) && depend_tx->chan == tx->chan) {
	txd_chain(depend_tx, tx);
	intr_tx = NULL;
	}
	txd_unlock(depend_tx);

	/* attached dependency, flush the parent channel */
	if (!intr_tx) {
	device->device_issue_pending(chan);
	return;
	}

	/* see if we can schedule an interrupt
	* otherwise poll for completion
	*/
	if (dma_has_cap(DMA_INTERRUPT, device->cap_mask))
	intr_tx = device->device_prep_dma_interrupt(chan, 0);
	else
	intr_tx = NULL;

	if (intr_tx) {
	intr_tx->callback = NULL;
	intr_tx->callback_param = NULL;
	/* safe to chain outside the lock since we know we are
	* not submitted yet
	*/
	txd_chain(intr_tx, tx);

	/* check if we need to append */
	txd_lock(depend_tx);
	if (txd_parent(depend_tx)) {
	txd_chain(depend_tx, intr_tx);
	async_tx_ack(intr_tx);
	intr_tx = NULL;
	}
	txd_unlock(depend_tx);

	if (intr_tx) {
	txd_clear_parent(intr_tx);
	intr_tx->tx_submit(intr_tx);
	async_tx_ack(intr_tx);
	}
	device->device_issue_pending(chan);
	} else {
	if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
	panic("%s: DMA_ERROR waiting for depend_tx\n",
	__func__);
	tx->tx_submit(tx);
	}
	}


	/**
	* submit_disposition - flags for routing an incoming operation
	* @ASYNC_TX_SUBMITTED: we were able to append the new operation under the lock
	* @ASYNC_TX_CHANNEL_SWITCH: when the lock is dropped schedule a channel switch
	* @ASYNC_TX_DIRECT_SUBMIT: when the lock is dropped submit directly
	*
	* while holding depend_tx->lock we must avoid submitting new operations
	* to prevent a circular locking dependency with drivers that already
	* hold a channel lock when calling async_tx_run_dependencies.
	*/
	enum submit_disposition {
	ASYNC_TX_SUBMITTED,
	ASYNC_TX_CHANNEL_SWITCH,
	ASYNC_TX_DIRECT_SUBMIT,
	};

	void
	async_tx_submit(struct dma_chan chan, struct dma_async_tx_descriptor tx,
	struct async_submit_ctl *submit)
	{
	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;

	tx->callback = submit->cb_fn;
	tx->callback_param = submit->cb_param;

	if (depend_tx) {
	enum submit_disposition s;

	/* sanity check the dependency chain:
	* 1/ if ack is already set then we cannot be sure
	* we are referring to the correct operation
	* 2/ dependencies are 1:1 i.e. two transactions can
	* not depend on the same parent
	*/
	BUG_ON(async_tx_test_ack(depend_tx) \|\| txd_next(depend_tx) \|\|
	txd_parent(tx));

	/* the lock prevents async_tx_run_dependencies from missing
	* the setting of ->next when ->parent != NULL
	*/
	txd_lock(depend_tx);
	if (txd_parent(depend_tx)) {
	/* we have a parent so we can not submit directly
	* if we are staying on the same channel: append
	* else: channel switch
	*/
	if (depend_tx->chan == chan) {
	txd_chain(depend_tx, tx);
	s = ASYNC_TX_SUBMITTED;
	} else
	s = ASYNC_TX_CHANNEL_SWITCH;
	} else {
	/* we do not have a parent so we may be able to submit
	* directly if we are staying on the same channel
	*/
	if (depend_tx->chan == chan)
	s = ASYNC_TX_DIRECT_SUBMIT;
	else
	s = ASYNC_TX_CHANNEL_SWITCH;
	}
	txd_unlock(depend_tx);

	switch (s) {
	case ASYNC_TX_SUBMITTED:
	break;
	case ASYNC_TX_CHANNEL_SWITCH:
	async_tx_channel_switch(depend_tx, tx);
	break;
	case ASYNC_TX_DIRECT_SUBMIT:
	txd_clear_parent(tx);
	tx->tx_submit(tx);
	break;
	}
	} else {
	txd_clear_parent(tx);
	tx->tx_submit(tx);
	}

	if (submit->flags & ASYNC_TX_ACK)
	async_tx_ack(tx);

	if (depend_tx)
	async_tx_ack(depend_tx);
	}
	EXPORT_SYMBOL_GPL(async_tx_submit);

	/**
	* async_trigger_callback - schedules the callback function to be run
	* @submit: submission and completion parameters
	*
	* honored flags: ASYNC_TX_ACK
	*
	* The callback is run after any dependent operations have completed.
	*/
	struct dma_async_tx_descriptor *
	async_trigger_callback(struct async_submit_ctl *submit)
	{
	struct dma_chan *chan;
	struct dma_device *device;
	struct dma_async_tx_descriptor *tx;
	struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;

	if (depend_tx) {
	chan = depend_tx->chan;
	device = chan->device;

	/* see if we can schedule an interrupt
	* otherwise poll for completion
	*/
	if (device && !dma_has_cap(DMA_INTERRUPT, device->cap_mask))
	device = NULL;

	tx = device ? device->device_prep_dma_interrupt(chan, 0) : NULL;
	} else
	tx = NULL;

	if (tx) {
	pr_debug("%s: (async)\n", __func__);

	async_tx_submit(chan, tx, submit);
	} else {
	pr_debug("%s: (sync)\n", __func__);

	/* wait for any prerequisite operations */
	async_tx_quiesce(&submit->depend_tx);

	async_tx_sync_epilog(submit);
	}

	return tx;
	}
	EXPORT_SYMBOL_GPL(async_trigger_callback);

	/**
	* async_tx_quiesce - ensure tx is complete and freeable upon return
	* @tx - transaction to quiesce
	*/
	void async_tx_quiesce(struct dma_async_tx_descriptor **tx)
	{
	if (*tx) {
	/* if ack is already set then we cannot be sure
	* we are referring to the correct operation
	*/
	BUG_ON(async_tx_test_ack(*tx));
	if (dma_wait_for_async_tx(*tx) == DMA_ERROR)
	panic("DMA_ERROR waiting for transaction\n");
	async_tx_ack(*tx);
	*tx = NULL;
	}
	}
	EXPORT_SYMBOL_GPL(async_tx_quiesce);

	MODULE_AUTHOR("Intel Corporation");
	MODULE_DESCRIPTION("Asynchronous Bulk Memory Transactions API");
	MODULE_LICENSE("GPL");