/*
   * Dmaengine driver base library for DMA controllers, found on SH-based SoCs
   *
   * extracted from shdma.c
   *
   * Copyright (C) 2011-2012 Guennadi Liakhovetski <g.liakhovetski@gmx.de>
   * Copyright (C) 2009 Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
   * Copyright (C) 2009 Renesas Solutions, Inc. All rights reserved.
   * Copyright (C) 2007 Freescale Semiconductor, Inc. All rights reserved.
   *
   * This is free software; you can redistribute it and/or modify
   * it under the terms of version 2 of the GNU General Public License as
   * published by the Free Software Foundation.
   */
  
  #include <linux/delay.h>
  #include <linux/shdma-base.h>
  #include <linux/dmaengine.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/module.h>
  #include <linux/pm_runtime.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>
  
  #include "../dmaengine.h"
  
  /* DMA descriptor control */
  enum shdma_desc_status {
  	DESC_IDLE,
  	DESC_PREPARED,
  	DESC_SUBMITTED,
  	DESC_COMPLETED,	/* completed, have to call callback */
  	DESC_WAITING,	/* callback called, waiting for ack / re-submit */
  };
  
  #define NR_DESCS_PER_CHANNEL 32
  
  #define to_shdma_chan(c) container_of(c, struct shdma_chan, dma_chan)
  #define to_shdma_dev(d) container_of(d, struct shdma_dev, dma_dev)
  
  /*
   * For slave DMA we assume, that there is a finite number of DMA slaves in the
   * system, and that each such slave can only use a finite number of channels.
   * We use slave channel IDs to make sure, that no such slave channel ID is
   * allocated more than once.
   */
  static unsigned int slave_num = 256;
  module_param(slave_num, uint, 0444);
  
  /* A bitmask with slave_num bits */
  static unsigned long *shdma_slave_used;
  
  /* Called under spin_lock_irq(&schan->chan_lock") */
  static void shdma_chan_xfer_ld_queue(struct shdma_chan *schan)
  {
  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
  	const struct shdma_ops *ops = sdev->ops;
  	struct shdma_desc *sdesc;
  
  	/* DMA work check */
  	if (ops->channel_busy(schan))
  		return;
  
  	/* Find the first not transferred descriptor */
  	list_for_each_entry(sdesc, &schan->ld_queue, node)
  		if (sdesc->mark == DESC_SUBMITTED) {
  			ops->start_xfer(schan, sdesc);
  			break;
  		}
  }
  
  static dma_cookie_t shdma_tx_submit(struct dma_async_tx_descriptor *tx)
  {
  	struct shdma_desc *chunk, *c, *desc =
  		container_of(tx, struct shdma_desc, async_tx),
  		*last = desc;
  	struct shdma_chan *schan = to_shdma_chan(tx->chan);
  	dma_async_tx_callback callback = tx->callback;
  	dma_cookie_t cookie;
  	bool power_up;
  
  	spin_lock_irq(&schan->chan_lock);
  
  	power_up = list_empty(&schan->ld_queue);
  
  	cookie = dma_cookie_assign(tx);
  
  	/* Mark all chunks of this descriptor as submitted, move to the queue */
  	list_for_each_entry_safe(chunk, c, desc->node.prev, node) {
  		/*
  		 * All chunks are on the global ld_free, so, we have to find
  		 * the end of the chain ourselves
  		 */
  		if (chunk != desc && (chunk->mark == DESC_IDLE ||
  				      chunk->async_tx.cookie > 0 ||
  				      chunk->async_tx.cookie == -EBUSY ||
  				      &chunk->node == &schan->ld_free))
  			break;
  		chunk->mark = DESC_SUBMITTED;
  		/* Callback goes to the last chunk */
  		chunk->async_tx.callback = NULL;
  		chunk->cookie = cookie;
  		list_move_tail(&chunk->node, &schan->ld_queue);
  		last = chunk;
  
  		dev_dbg(schan->dev, "submit #%d@%p on %d
  ",
  			tx->cookie, &last->async_tx, schan->id);
  	}
  
  	last->async_tx.callback = callback;
  	last->async_tx.callback_param = tx->callback_param;
  
  	if (power_up) {
  		int ret;
  		schan->pm_state = SHDMA_PM_BUSY;
  
  		ret = pm_runtime_get(schan->dev);
  
  		spin_unlock_irq(&schan->chan_lock);
  		if (ret < 0)
  			dev_err(schan->dev, "%s(): GET = %d
  ", __func__, ret);
  
  		pm_runtime_barrier(schan->dev);
  
  		spin_lock_irq(&schan->chan_lock);
  
  		/* Have we been reset, while waiting? */
  		if (schan->pm_state != SHDMA_PM_ESTABLISHED) {
  			struct shdma_dev *sdev =
  				to_shdma_dev(schan->dma_chan.device);
  			const struct shdma_ops *ops = sdev->ops;
  			dev_dbg(schan->dev, "Bring up channel %d
  ",
  				schan->id);
  			/*
  			 * TODO: .xfer_setup() might fail on some platforms.
  			 * Make it int then, on error remove chunks from the
  			 * queue again
  			 */
  			ops->setup_xfer(schan, schan->slave_id);
  
  			if (schan->pm_state == SHDMA_PM_PENDING)
  				shdma_chan_xfer_ld_queue(schan);
  			schan->pm_state = SHDMA_PM_ESTABLISHED;
  		}
  	} else {
  		/*
  		 * Tell .device_issue_pending() not to run the queue, interrupts
  		 * will do it anyway
  		 */
  		schan->pm_state = SHDMA_PM_PENDING;
  	}
  
  	spin_unlock_irq(&schan->chan_lock);
  
  	return cookie;
  }
  
  /* Called with desc_lock held */
  static struct shdma_desc *shdma_get_desc(struct shdma_chan *schan)
  {
  	struct shdma_desc *sdesc;
  
  	list_for_each_entry(sdesc, &schan->ld_free, node)
  		if (sdesc->mark != DESC_PREPARED) {
  			BUG_ON(sdesc->mark != DESC_IDLE);
  			list_del(&sdesc->node);
  			return sdesc;
  		}
  
  	return NULL;
  }
  
  static int shdma_setup_slave(struct shdma_chan *schan, int slave_id,
  			     dma_addr_t slave_addr)
  {
  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
  	const struct shdma_ops *ops = sdev->ops;
  	int ret, match;
  
  	if (schan->dev->of_node) {
  		match = schan->hw_req;
  		ret = ops->set_slave(schan, match, slave_addr, true);
  		if (ret < 0)
  			return ret;
  
  		slave_id = schan->slave_id;
  	} else {
  		match = slave_id;
  	}
  
  	if (slave_id < 0 || slave_id >= slave_num)
  		return -EINVAL;
  
  	if (test_and_set_bit(slave_id, shdma_slave_used))
  		return -EBUSY;
  
  	ret = ops->set_slave(schan, match, slave_addr, false);
  	if (ret < 0) {
  		clear_bit(slave_id, shdma_slave_used);
  		return ret;
  	}
  
  	schan->slave_id = slave_id;
  
  	return 0;
  }
  
  /*
   * This is the standard shdma filter function to be used as a replacement to the
   * "old" method, using the .private pointer. If for some reason you allocate a
   * channel without slave data, use something like ERR_PTR(-EINVAL) as a filter
   * parameter. If this filter is used, the slave driver, after calling
   * dma_request_channel(), will also have to call dmaengine_slave_config() with
   * .slave_id, .direction, and either .src_addr or .dst_addr set.
   * NOTE: this filter doesn't support multiple DMAC drivers with the DMA_SLAVE
   * capability! If this becomes a requirement, hardware glue drivers, using this
   * services would have to provide their own filters, which first would check
   * the device driver, similar to how other DMAC drivers, e.g., sa11x0-dma.c, do
   * this, and only then, in case of a match, call this common filter.
   * NOTE 2: This filter function is also used in the DT case by shdma_of_xlate().
   * In that case the MID-RID value is used for slave channel filtering and is
   * passed to this function in the "arg" parameter.
   */
  bool shdma_chan_filter(struct dma_chan *chan, void *arg)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
  	const struct shdma_ops *ops = sdev->ops;
  	int match = (int)arg;
  	int ret;
  
  	if (match < 0)
  		/* No slave requested - arbitrary channel */
  		return true;
  
  	if (!schan->dev->of_node && match >= slave_num)
  		return false;
  
  	ret = ops->set_slave(schan, match, 0, true);
  	if (ret < 0)
  		return false;
  
  	return true;
  }
  EXPORT_SYMBOL(shdma_chan_filter);
  
  static int shdma_alloc_chan_resources(struct dma_chan *chan)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
  	const struct shdma_ops *ops = sdev->ops;
  	struct shdma_desc *desc;
  	struct shdma_slave *slave = chan->private;
  	int ret, i;
  
  	/*
  	 * This relies on the guarantee from dmaengine that alloc_chan_resources
  	 * never runs concurrently with itself or free_chan_resources.
  	 */
  	if (slave) {
  		/* Legacy mode: .private is set in filter */
  		ret = shdma_setup_slave(schan, slave->slave_id, 0);
  		if (ret < 0)
  			goto esetslave;
  	} else {
  		schan->slave_id = -EINVAL;
  	}
  
  	schan->desc = kcalloc(NR_DESCS_PER_CHANNEL,
  			      sdev->desc_size, GFP_KERNEL);
  	if (!schan->desc) {
  		ret = -ENOMEM;
  		goto edescalloc;
  	}
  	schan->desc_num = NR_DESCS_PER_CHANNEL;
  
  	for (i = 0; i < NR_DESCS_PER_CHANNEL; i++) {
  		desc = ops->embedded_desc(schan->desc, i);
  		dma_async_tx_descriptor_init(&desc->async_tx,
  					     &schan->dma_chan);
  		desc->async_tx.tx_submit = shdma_tx_submit;
  		desc->mark = DESC_IDLE;
  
  		list_add(&desc->node, &schan->ld_free);
  	}
  
  	return NR_DESCS_PER_CHANNEL;
  
  edescalloc:
  	if (slave)
  esetslave:
  		clear_bit(slave->slave_id, shdma_slave_used);
  	chan->private = NULL;
  	return ret;
  }
  
  static dma_async_tx_callback __ld_cleanup(struct shdma_chan *schan, bool all)
  {
  	struct shdma_desc *desc, *_desc;
  	/* Is the "exposed" head of a chain acked? */
  	bool head_acked = false;
  	dma_cookie_t cookie = 0;
  	dma_async_tx_callback callback = NULL;
  	void *param = NULL;
  	unsigned long flags;
  
  	spin_lock_irqsave(&schan->chan_lock, flags);
  	list_for_each_entry_safe(desc, _desc, &schan->ld_queue, node) {
  		struct dma_async_tx_descriptor *tx = &desc->async_tx;
  
  		BUG_ON(tx->cookie > 0 && tx->cookie != desc->cookie);
  		BUG_ON(desc->mark != DESC_SUBMITTED &&
  		       desc->mark != DESC_COMPLETED &&
  		       desc->mark != DESC_WAITING);
  
  		/*
  		 * queue is ordered, and we use this loop to (1) clean up all
  		 * completed descriptors, and to (2) update descriptor flags of
  		 * any chunks in a (partially) completed chain
  		 */
  		if (!all && desc->mark == DESC_SUBMITTED &&
  		    desc->cookie != cookie)
  			break;
  
  		if (tx->cookie > 0)
  			cookie = tx->cookie;
  
  		if (desc->mark == DESC_COMPLETED && desc->chunks == 1) {
  			if (schan->dma_chan.completed_cookie != desc->cookie - 1)
  				dev_dbg(schan->dev,
  					"Completing cookie %d, expected %d
  ",
  					desc->cookie,
  					schan->dma_chan.completed_cookie + 1);
  			schan->dma_chan.completed_cookie = desc->cookie;
  		}
  
  		/* Call callback on the last chunk */
  		if (desc->mark == DESC_COMPLETED && tx->callback) {
  			desc->mark = DESC_WAITING;
  			callback = tx->callback;
  			param = tx->callback_param;
  			dev_dbg(schan->dev, "descriptor #%d@%p on %d callback
  ",
  				tx->cookie, tx, schan->id);
  			BUG_ON(desc->chunks != 1);
  			break;
  		}
  
  		if (tx->cookie > 0 || tx->cookie == -EBUSY) {
  			if (desc->mark == DESC_COMPLETED) {
  				BUG_ON(tx->cookie < 0);
  				desc->mark = DESC_WAITING;
  			}
  			head_acked = async_tx_test_ack(tx);
  		} else {
  			switch (desc->mark) {
  			case DESC_COMPLETED:
  				desc->mark = DESC_WAITING;
  				/* Fall through */
  			case DESC_WAITING:
  				if (head_acked)
  					async_tx_ack(&desc->async_tx);
  			}
  		}
  
  		dev_dbg(schan->dev, "descriptor %p #%d completed.
  ",
  			tx, tx->cookie);
  
  		if (((desc->mark == DESC_COMPLETED ||
  		      desc->mark == DESC_WAITING) &&
  		     async_tx_test_ack(&desc->async_tx)) || all) {
  			/* Remove from ld_queue list */
  			desc->mark = DESC_IDLE;
  
  			list_move(&desc->node, &schan->ld_free);
  
  			if (list_empty(&schan->ld_queue)) {
  				dev_dbg(schan->dev, "Bring down channel %d
  ", schan->id);
  				pm_runtime_put(schan->dev);
  				schan->pm_state = SHDMA_PM_ESTABLISHED;
  			}
  		}
  	}
  
  	if (all && !callback)
  		/*
  		 * Terminating and the loop completed normally: forgive
  		 * uncompleted cookies
  		 */
  		schan->dma_chan.completed_cookie = schan->dma_chan.cookie;
  
  	spin_unlock_irqrestore(&schan->chan_lock, flags);
  
  	if (callback)
  		callback(param);
  
  	return callback;
  }
  
  /*
   * shdma_chan_ld_cleanup - Clean up link descriptors
   *
   * Clean up the ld_queue of DMA channel.
   */
  static void shdma_chan_ld_cleanup(struct shdma_chan *schan, bool all)
  {
  	while (__ld_cleanup(schan, all))
  		;
  }
  
  /*
   * shdma_free_chan_resources - Free all resources of the channel.
   */
  static void shdma_free_chan_resources(struct dma_chan *chan)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  	struct shdma_dev *sdev = to_shdma_dev(chan->device);
  	const struct shdma_ops *ops = sdev->ops;
  	LIST_HEAD(list);
  
  	/* Protect against ISR */
  	spin_lock_irq(&schan->chan_lock);
  	ops->halt_channel(schan);
  	spin_unlock_irq(&schan->chan_lock);
  
  	/* Now no new interrupts will occur */
  
  	/* Prepared and not submitted descriptors can still be on the queue */
  	if (!list_empty(&schan->ld_queue))
  		shdma_chan_ld_cleanup(schan, true);
  
  	if (schan->slave_id >= 0) {
  		/* The caller is holding dma_list_mutex */
  		clear_bit(schan->slave_id, shdma_slave_used);
  		chan->private = NULL;
  	}
  
  	spin_lock_irq(&schan->chan_lock);
  
  	list_splice_init(&schan->ld_free, &list);
  	schan->desc_num = 0;
  
  	spin_unlock_irq(&schan->chan_lock);
  
  	kfree(schan->desc);
  }
  
  /**
   * shdma_add_desc - get, set up and return one transfer descriptor
   * @schan:	DMA channel
   * @flags:	DMA transfer flags
   * @dst:	destination DMA address, incremented when direction equals
   *		DMA_DEV_TO_MEM or DMA_MEM_TO_MEM
   * @src:	source DMA address, incremented when direction equals
   *		DMA_MEM_TO_DEV or DMA_MEM_TO_MEM
   * @len:	DMA transfer length
   * @first:	if NULL, set to the current descriptor and cookie set to -EBUSY
   * @direction:	needed for slave DMA to decide which address to keep constant,
   *		equals DMA_MEM_TO_MEM for MEMCPY
   * Returns 0 or an error
   * Locks: called with desc_lock held
   */
  static struct shdma_desc *shdma_add_desc(struct shdma_chan *schan,
  	unsigned long flags, dma_addr_t *dst, dma_addr_t *src, size_t *len,
  	struct shdma_desc **first, enum dma_transfer_direction direction)
  {
  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
  	const struct shdma_ops *ops = sdev->ops;
  	struct shdma_desc *new;
  	size_t copy_size = *len;
  
  	if (!copy_size)
  		return NULL;
  
  	/* Allocate the link descriptor from the free list */
  	new = shdma_get_desc(schan);
  	if (!new) {
  		dev_err(schan->dev, "No free link descriptor available
  ");
  		return NULL;
  	}
  
  	ops->desc_setup(schan, new, *src, *dst, &copy_size);
  
  	if (!*first) {
  		/* First desc */
  		new->async_tx.cookie = -EBUSY;
  		*first = new;
  	} else {
  		/* Other desc - invisible to the user */
  		new->async_tx.cookie = -EINVAL;
  	}
  
  	dev_dbg(schan->dev,
  		"chaining (%u/%u)@%x -> %x with %p, cookie %d
  ",
  		copy_size, *len, *src, *dst, &new->async_tx,
  		new->async_tx.cookie);
  
  	new->mark = DESC_PREPARED;
  	new->async_tx.flags = flags;
  	new->direction = direction;
  	new->partial = 0;
  
  	*len -= copy_size;
  	if (direction == DMA_MEM_TO_MEM || direction == DMA_MEM_TO_DEV)
  		*src += copy_size;
  	if (direction == DMA_MEM_TO_MEM || direction == DMA_DEV_TO_MEM)
  		*dst += copy_size;
  
  	return new;
  }
  
  /*
   * shdma_prep_sg - prepare transfer descriptors from an SG list
   *
   * Common routine for public (MEMCPY) and slave DMA. The MEMCPY case is also
   * converted to scatter-gather to guarantee consistent locking and a correct
   * list manipulation. For slave DMA direction carries the usual meaning, and,
   * logically, the SG list is RAM and the addr variable contains slave address,
   * e.g., the FIFO I/O register. For MEMCPY direction equals DMA_MEM_TO_MEM
   * and the SG list contains only one element and points at the source buffer.
   */
  static struct dma_async_tx_descriptor *shdma_prep_sg(struct shdma_chan *schan,
  	struct scatterlist *sgl, unsigned int sg_len, dma_addr_t *addr,
  	enum dma_transfer_direction direction, unsigned long flags)
  {
  	struct scatterlist *sg;
  	struct shdma_desc *first = NULL, *new = NULL /* compiler... */;
  	LIST_HEAD(tx_list);
  	int chunks = 0;
  	unsigned long irq_flags;
  	int i;
  
  	for_each_sg(sgl, sg, sg_len, i)
  		chunks += DIV_ROUND_UP(sg_dma_len(sg), schan->max_xfer_len);
  
  	/* Have to lock the whole loop to protect against concurrent release */
  	spin_lock_irqsave(&schan->chan_lock, irq_flags);
  
  	/*
  	 * Chaining:
  	 * first descriptor is what user is dealing with in all API calls, its
  	 *	cookie is at first set to -EBUSY, at tx-submit to a positive
  	 *	number
  	 * if more than one chunk is needed further chunks have cookie = -EINVAL
  	 * the last chunk, if not equal to the first, has cookie = -ENOSPC
  	 * all chunks are linked onto the tx_list head with their .node heads
  	 *	only during this function, then they are immediately spliced
  	 *	back onto the free list in form of a chain
  	 */
  	for_each_sg(sgl, sg, sg_len, i) {
  		dma_addr_t sg_addr = sg_dma_address(sg);
  		size_t len = sg_dma_len(sg);
  
  		if (!len)
  			goto err_get_desc;
  
  		do {
  			dev_dbg(schan->dev, "Add SG #%d@%p[%d], dma %llx
  ",
  				i, sg, len, (unsigned long long)sg_addr);
  
  			if (direction == DMA_DEV_TO_MEM)
  				new = shdma_add_desc(schan, flags,
  						&sg_addr, addr, &len, &first,
  						direction);
  			else
  				new = shdma_add_desc(schan, flags,
  						addr, &sg_addr, &len, &first,
  						direction);
  			if (!new)
  				goto err_get_desc;
  
  			new->chunks = chunks--;
  			list_add_tail(&new->node, &tx_list);
  		} while (len);
  	}
  
  	if (new != first)
  		new->async_tx.cookie = -ENOSPC;
  
  	/* Put them back on the free list, so, they don't get lost */
  	list_splice_tail(&tx_list, &schan->ld_free);
  
  	spin_unlock_irqrestore(&schan->chan_lock, irq_flags);
  
  	return &first->async_tx;
  
  err_get_desc:
  	list_for_each_entry(new, &tx_list, node)
  		new->mark = DESC_IDLE;
  	list_splice(&tx_list, &schan->ld_free);
  
  	spin_unlock_irqrestore(&schan->chan_lock, irq_flags);
  
  	return NULL;
  }
  
  static struct dma_async_tx_descriptor *shdma_prep_memcpy(
  	struct dma_chan *chan, dma_addr_t dma_dest, dma_addr_t dma_src,
  	size_t len, unsigned long flags)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  	struct scatterlist sg;
  
  	if (!chan || !len)
  		return NULL;
  
  	BUG_ON(!schan->desc_num);
  
  	sg_init_table(&sg, 1);
  	sg_set_page(&sg, pfn_to_page(PFN_DOWN(dma_src)), len,
  		    offset_in_page(dma_src));
  	sg_dma_address(&sg) = dma_src;
  	sg_dma_len(&sg) = len;
  
  	return shdma_prep_sg(schan, &sg, 1, &dma_dest, DMA_MEM_TO_MEM, flags);
  }
  
  static struct dma_async_tx_descriptor *shdma_prep_slave_sg(
  	struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len,
  	enum dma_transfer_direction direction, unsigned long flags, void *context)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
  	const struct shdma_ops *ops = sdev->ops;
  	int slave_id = schan->slave_id;
  	dma_addr_t slave_addr;
  
  	if (!chan)
  		return NULL;
  
  	BUG_ON(!schan->desc_num);
  
  	/* Someone calling slave DMA on a generic channel? */
  	if (slave_id < 0 || !sg_len) {
  		dev_warn(schan->dev, "%s: bad parameter: len=%d, id=%d
  ",
  			 __func__, sg_len, slave_id);
  		return NULL;
  	}
  
  	slave_addr = ops->slave_addr(schan);
  
  	return shdma_prep_sg(schan, sgl, sg_len, &slave_addr,
  			      direction, flags);
  }
  
  static int shdma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
  			  unsigned long arg)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  	struct shdma_dev *sdev = to_shdma_dev(chan->device);
  	const struct shdma_ops *ops = sdev->ops;
  	struct dma_slave_config *config;
  	unsigned long flags;
  	int ret;
  
  	switch (cmd) {
  	case DMA_TERMINATE_ALL:
  		spin_lock_irqsave(&schan->chan_lock, flags);
  		ops->halt_channel(schan);
  
  		if (ops->get_partial && !list_empty(&schan->ld_queue)) {
  			/* Record partial transfer */
  			struct shdma_desc *desc = list_first_entry(&schan->ld_queue,
  						struct shdma_desc, node);
  			desc->partial = ops->get_partial(schan, desc);
  		}
  
  		spin_unlock_irqrestore(&schan->chan_lock, flags);
  
  		shdma_chan_ld_cleanup(schan, true);
  		break;
  	case DMA_SLAVE_CONFIG:
  		/*
  		 * So far only .slave_id is used, but the slave drivers are
  		 * encouraged to also set a transfer direction and an address.
  		 */
  		if (!arg)
  			return -EINVAL;
  		/*
  		 * We could lock this, but you shouldn't be configuring the
  		 * channel, while using it...
  		 */
  		config = (struct dma_slave_config *)arg;
  		ret = shdma_setup_slave(schan, config->slave_id,
  					config->direction == DMA_DEV_TO_MEM ?
  					config->src_addr : config->dst_addr);
  		if (ret < 0)
  			return ret;
  		break;
  	default:
  		return -ENXIO;
  	}
  
  	return 0;
  }
  
  static void shdma_issue_pending(struct dma_chan *chan)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  
  	spin_lock_irq(&schan->chan_lock);
  	if (schan->pm_state == SHDMA_PM_ESTABLISHED)
  		shdma_chan_xfer_ld_queue(schan);
  	else
  		schan->pm_state = SHDMA_PM_PENDING;
  	spin_unlock_irq(&schan->chan_lock);
  }
  
  static enum dma_status shdma_tx_status(struct dma_chan *chan,
  					dma_cookie_t cookie,
  					struct dma_tx_state *txstate)
  {
  	struct shdma_chan *schan = to_shdma_chan(chan);
  	enum dma_status status;
  	unsigned long flags;
  
  	shdma_chan_ld_cleanup(schan, false);
  
  	spin_lock_irqsave(&schan->chan_lock, flags);
  
  	status = dma_cookie_status(chan, cookie, txstate);
  
  	/*
  	 * If we don't find cookie on the queue, it has been aborted and we have
  	 * to report error
  	 */
  	if (status != DMA_COMPLETE) {
  		struct shdma_desc *sdesc;
  		status = DMA_ERROR;
  		list_for_each_entry(sdesc, &schan->ld_queue, node)
  			if (sdesc->cookie == cookie) {
  				status = DMA_IN_PROGRESS;
  				break;
  			}
  	}
  
  	spin_unlock_irqrestore(&schan->chan_lock, flags);
  
  	return status;
  }
  
  /* Called from error IRQ or NMI */
  bool shdma_reset(struct shdma_dev *sdev)
  {
  	const struct shdma_ops *ops = sdev->ops;
  	struct shdma_chan *schan;
  	unsigned int handled = 0;
  	int i;
  
  	/* Reset all channels */
  	shdma_for_each_chan(schan, sdev, i) {
  		struct shdma_desc *sdesc;
  		LIST_HEAD(dl);
  
  		if (!schan)
  			continue;
  
  		spin_lock(&schan->chan_lock);
  
  		/* Stop the channel */
  		ops->halt_channel(schan);
  
  		list_splice_init(&schan->ld_queue, &dl);
  
  		if (!list_empty(&dl)) {
  			dev_dbg(schan->dev, "Bring down channel %d
  ", schan->id);
  			pm_runtime_put(schan->dev);
  		}
  		schan->pm_state = SHDMA_PM_ESTABLISHED;
  
  		spin_unlock(&schan->chan_lock);
  
  		/* Complete all  */
  		list_for_each_entry(sdesc, &dl, node) {
  			struct dma_async_tx_descriptor *tx = &sdesc->async_tx;
  			sdesc->mark = DESC_IDLE;
  			if (tx->callback)
  				tx->callback(tx->callback_param);
  		}
  
  		spin_lock(&schan->chan_lock);
  		list_splice(&dl, &schan->ld_free);
  		spin_unlock(&schan->chan_lock);
  
  		handled++;
  	}
  
  	return !!handled;
  }
  EXPORT_SYMBOL(shdma_reset);
  
  static irqreturn_t chan_irq(int irq, void *dev)
  {
  	struct shdma_chan *schan = dev;
  	const struct shdma_ops *ops =
  		to_shdma_dev(schan->dma_chan.device)->ops;
  	irqreturn_t ret;
  
  	spin_lock(&schan->chan_lock);
  
  	ret = ops->chan_irq(schan, irq) ? IRQ_WAKE_THREAD : IRQ_NONE;
  
  	spin_unlock(&schan->chan_lock);
  
  	return ret;
  }
  
  static irqreturn_t chan_irqt(int irq, void *dev)
  {
  	struct shdma_chan *schan = dev;
  	const struct shdma_ops *ops =
  		to_shdma_dev(schan->dma_chan.device)->ops;
  	struct shdma_desc *sdesc;
  
  	spin_lock_irq(&schan->chan_lock);
  	list_for_each_entry(sdesc, &schan->ld_queue, node) {
  		if (sdesc->mark == DESC_SUBMITTED &&
  		    ops->desc_completed(schan, sdesc)) {
  			dev_dbg(schan->dev, "done #%d@%p
  ",
  				sdesc->async_tx.cookie, &sdesc->async_tx);
  			sdesc->mark = DESC_COMPLETED;
  			break;
  		}
  	}
  	/* Next desc */
  	shdma_chan_xfer_ld_queue(schan);
  	spin_unlock_irq(&schan->chan_lock);
  
  	shdma_chan_ld_cleanup(schan, false);
  
  	return IRQ_HANDLED;
  }
  
  int shdma_request_irq(struct shdma_chan *schan, int irq,
  			   unsigned long flags, const char *name)
  {
  	int ret = devm_request_threaded_irq(schan->dev, irq, chan_irq,
  					    chan_irqt, flags, name, schan);
  
  	schan->irq = ret < 0 ? ret : irq;
  
  	return ret;
  }
  EXPORT_SYMBOL(shdma_request_irq);
  
  void shdma_chan_probe(struct shdma_dev *sdev,
  			   struct shdma_chan *schan, int id)
  {
  	schan->pm_state = SHDMA_PM_ESTABLISHED;
  
  	/* reference struct dma_device */
  	schan->dma_chan.device = &sdev->dma_dev;
  	dma_cookie_init(&schan->dma_chan);
  
  	schan->dev = sdev->dma_dev.dev;
  	schan->id = id;
  
  	if (!schan->max_xfer_len)
  		schan->max_xfer_len = PAGE_SIZE;
  
  	spin_lock_init(&schan->chan_lock);
  
  	/* Init descripter manage list */
  	INIT_LIST_HEAD(&schan->ld_queue);
  	INIT_LIST_HEAD(&schan->ld_free);
  
  	/* Add the channel to DMA device channel list */
  	list_add_tail(&schan->dma_chan.device_node,
  			&sdev->dma_dev.channels);
  	sdev->schan[sdev->dma_dev.chancnt++] = schan;
  }
  EXPORT_SYMBOL(shdma_chan_probe);
  
  void shdma_chan_remove(struct shdma_chan *schan)
  {
  	list_del(&schan->dma_chan.device_node);
  }
  EXPORT_SYMBOL(shdma_chan_remove);
  
  int shdma_init(struct device *dev, struct shdma_dev *sdev,
  		    int chan_num)
  {
  	struct dma_device *dma_dev = &sdev->dma_dev;
  
  	/*
  	 * Require all call-backs for now, they can trivially be made optional
  	 * later as required
  	 */
  	if (!sdev->ops ||
  	    !sdev->desc_size ||
  	    !sdev->ops->embedded_desc ||
  	    !sdev->ops->start_xfer ||
  	    !sdev->ops->setup_xfer ||
  	    !sdev->ops->set_slave ||
  	    !sdev->ops->desc_setup ||
  	    !sdev->ops->slave_addr ||
  	    !sdev->ops->channel_busy ||
  	    !sdev->ops->halt_channel ||
  	    !sdev->ops->desc_completed)
  		return -EINVAL;
  
  	sdev->schan = kcalloc(chan_num, sizeof(*sdev->schan), GFP_KERNEL);
  	if (!sdev->schan)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&dma_dev->channels);
  
  	/* Common and MEMCPY operations */
  	dma_dev->device_alloc_chan_resources
  		= shdma_alloc_chan_resources;
  	dma_dev->device_free_chan_resources = shdma_free_chan_resources;
  	dma_dev->device_prep_dma_memcpy = shdma_prep_memcpy;
  	dma_dev->device_tx_status = shdma_tx_status;
  	dma_dev->device_issue_pending = shdma_issue_pending;
  
  	/* Compulsory for DMA_SLAVE fields */
  	dma_dev->device_prep_slave_sg = shdma_prep_slave_sg;
  	dma_dev->device_control = shdma_control;
  
  	dma_dev->dev = dev;
  
  	return 0;
  }
  EXPORT_SYMBOL(shdma_init);
  
  void shdma_cleanup(struct shdma_dev *sdev)
  {
  	kfree(sdev->schan);
  }
  EXPORT_SYMBOL(shdma_cleanup);
  
  static int __init shdma_enter(void)
  {
  	shdma_slave_used = kzalloc(DIV_ROUND_UP(slave_num, BITS_PER_LONG) *
  				    sizeof(long), GFP_KERNEL);
  	if (!shdma_slave_used)
  		return -ENOMEM;
  	return 0;
  }
  module_init(shdma_enter);
  
  static void __exit shdma_exit(void)
  {
  	kfree(shdma_slave_used);
  }
  module_exit(shdma_exit);
  
  MODULE_LICENSE("GPL v2");
  MODULE_DESCRIPTION("SH-DMA driver base library");
  MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de>");