/*
   * Copyright (C) Freescale Semicondutor, Inc. 2007, 2008.
   * Copyright (C) Semihalf 2009

   * Copyright (C) Ilya Yanok, Emcraft Systems 2010

   * Copyright (C) Alexander Popov, Promcontroller 2014

   * Copyright (C) Mario Six, Guntermann & Drunck GmbH, 2016

   *
   * Written by Piotr Ziecik <kosmo@semihalf.com>. Hardware description
   * (defines, structures and comments) was taken from MPC5121 DMA driver
   * written by Hongjun Chen <hong-jun.chen@freescale.com>.
   *
   * Approved as OSADL project by a majority of OSADL members and funded
   * by OSADL membership fees in 2009;  for details see www.osadl.org.
   *
   * 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.
   *

   * The full GNU General Public License is included in this distribution in the
   * file called COPYING.
   */
  
  /*

   * MPC512x and MPC8308 DMA driver. It supports memory to memory data transfers
   * (tested using dmatest module) and data transfers between memory and
   * peripheral I/O memory by means of slave scatter/gather with these
   * limitations:
   *  - chunked transfers (described by s/g lists with more than one item) are
   *     refused as long as proper support for scatter/gather is missing
   *  - transfers on MPC8308 always start from software as this SoC does not have
   *     external request lines for peripheral flow control
   *  - memory <-> I/O memory transfer chunks of sizes of 1, 2, 4, 16 (for
   *     MPC512x), and 32 bytes are supported, and, consequently, source
   *     addresses and destination addresses must be aligned accordingly;
   *     furthermore, for MPC512x SoCs, the transfer size must be aligned on
   *     (chunk size * maxburst)

   */
  
  #include <linux/module.h>
  #include <linux/dmaengine.h>
  #include <linux/dma-mapping.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>

  #include <linux/slab.h>

  #include <linux/of_address.h>

  #include <linux/of_device.h>

  #include <linux/of_irq.h>

  #include <linux/of_dma.h>

  #include <linux/of_platform.h>
  
  #include <linux/random.h>

  #include "dmaengine.h"

  /* Number of DMA Transfer descriptors allocated per channel */
  #define MPC_DMA_DESCRIPTORS	64
  
  /* Macro definitions */

  #define MPC_DMA_TCD_OFFSET	0x1000

  /*
   * Maximum channel counts for individual hardware variants
   * and the maximum channel count over all supported controllers,
   * used for data structure size
   */
  #define MPC8308_DMACHAN_MAX	16
  #define MPC512x_DMACHAN_MAX	64
  #define MPC_DMA_CHANNELS	64

  /* Arbitration mode of group and channel */
  #define MPC_DMA_DMACR_EDCG	(1 << 31)
  #define MPC_DMA_DMACR_ERGA	(1 << 3)
  #define MPC_DMA_DMACR_ERCA	(1 << 2)
  
  /* Error codes */
  #define MPC_DMA_DMAES_VLD	(1 << 31)
  #define MPC_DMA_DMAES_GPE	(1 << 15)
  #define MPC_DMA_DMAES_CPE	(1 << 14)
  #define MPC_DMA_DMAES_ERRCHN(err) \
  				(((err) >> 8) & 0x3f)
  #define MPC_DMA_DMAES_SAE	(1 << 7)
  #define MPC_DMA_DMAES_SOE	(1 << 6)
  #define MPC_DMA_DMAES_DAE	(1 << 5)
  #define MPC_DMA_DMAES_DOE	(1 << 4)
  #define MPC_DMA_DMAES_NCE	(1 << 3)
  #define MPC_DMA_DMAES_SGE	(1 << 2)
  #define MPC_DMA_DMAES_SBE	(1 << 1)
  #define MPC_DMA_DMAES_DBE	(1 << 0)

  #define MPC_DMA_DMAGPOR_SNOOP_ENABLE	(1 << 6)

  #define MPC_DMA_TSIZE_1		0x00
  #define MPC_DMA_TSIZE_2		0x01
  #define MPC_DMA_TSIZE_4		0x02
  #define MPC_DMA_TSIZE_16	0x04
  #define MPC_DMA_TSIZE_32	0x05
  
  /* MPC5121 DMA engine registers */
  struct __attribute__ ((__packed__)) mpc_dma_regs {
  	/* 0x00 */
  	u32 dmacr;		/* DMA control register */
  	u32 dmaes;		/* DMA error status */
  	/* 0x08 */
  	u32 dmaerqh;		/* DMA enable request high(channels 63~32) */
  	u32 dmaerql;		/* DMA enable request low(channels 31~0) */
  	u32 dmaeeih;		/* DMA enable error interrupt high(ch63~32) */
  	u32 dmaeeil;		/* DMA enable error interrupt low(ch31~0) */
  	/* 0x18 */
  	u8 dmaserq;		/* DMA set enable request */
  	u8 dmacerq;		/* DMA clear enable request */
  	u8 dmaseei;		/* DMA set enable error interrupt */
  	u8 dmaceei;		/* DMA clear enable error interrupt */
  	/* 0x1c */
  	u8 dmacint;		/* DMA clear interrupt request */
  	u8 dmacerr;		/* DMA clear error */
  	u8 dmassrt;		/* DMA set start bit */
  	u8 dmacdne;		/* DMA clear DONE status bit */
  	/* 0x20 */
  	u32 dmainth;		/* DMA interrupt request high(ch63~32) */
  	u32 dmaintl;		/* DMA interrupt request low(ch31~0) */
  	u32 dmaerrh;		/* DMA error high(ch63~32) */
  	u32 dmaerrl;		/* DMA error low(ch31~0) */
  	/* 0x30 */
  	u32 dmahrsh;		/* DMA hw request status high(ch63~32) */
  	u32 dmahrsl;		/* DMA hardware request status low(ch31~0) */

  	union {
  		u32 dmaihsa;	/* DMA interrupt high select AXE(ch63~32) */
  		u32 dmagpor;	/* (General purpose register on MPC8308) */
  	};

  	u32 dmailsa;		/* DMA interrupt low select AXE(ch31~0) */
  	/* 0x40 ~ 0xff */
  	u32 reserve0[48];	/* Reserved */
  	/* 0x100 */
  	u8 dchpri[MPC_DMA_CHANNELS];
  	/* DMA channels(0~63) priority */
  };
  
  struct __attribute__ ((__packed__)) mpc_dma_tcd {
  	/* 0x00 */
  	u32 saddr;		/* Source address */
  
  	u32 smod:5;		/* Source address modulo */
  	u32 ssize:3;		/* Source data transfer size */
  	u32 dmod:5;		/* Destination address modulo */
  	u32 dsize:3;		/* Destination data transfer size */
  	u32 soff:16;		/* Signed source address offset */
  
  	/* 0x08 */
  	u32 nbytes;		/* Inner "minor" byte count */
  	u32 slast;		/* Last source address adjustment */
  	u32 daddr;		/* Destination address */
  
  	/* 0x14 */
  	u32 citer_elink:1;	/* Enable channel-to-channel linking on
  				 * minor loop complete
  				 */
  	u32 citer_linkch:6;	/* Link channel for minor loop complete */
  	u32 citer:9;		/* Current "major" iteration count */
  	u32 doff:16;		/* Signed destination address offset */
  
  	/* 0x18 */
  	u32 dlast_sga;		/* Last Destination address adjustment/scatter
  				 * gather address
  				 */
  
  	/* 0x1c */
  	u32 biter_elink:1;	/* Enable channel-to-channel linking on major
  				 * loop complete
  				 */
  	u32 biter_linkch:6;
  	u32 biter:9;		/* Beginning "major" iteration count */
  	u32 bwc:2;		/* Bandwidth control */
  	u32 major_linkch:6;	/* Link channel number */
  	u32 done:1;		/* Channel done */
  	u32 active:1;		/* Channel active */
  	u32 major_elink:1;	/* Enable channel-to-channel linking on major
  				 * loop complete
  				 */
  	u32 e_sg:1;		/* Enable scatter/gather processing */
  	u32 d_req:1;		/* Disable request */
  	u32 int_half:1;		/* Enable an interrupt when major counter is
  				 * half complete
  				 */
  	u32 int_maj:1;		/* Enable an interrupt when major iteration
  				 * count completes
  				 */
  	u32 start:1;		/* Channel start */
  };
  
  struct mpc_dma_desc {
  	struct dma_async_tx_descriptor	desc;
  	struct mpc_dma_tcd		*tcd;
  	dma_addr_t			tcd_paddr;
  	int				error;
  	struct list_head		node;

  	int				will_access_peripheral;

  };
  
  struct mpc_dma_chan {
  	struct dma_chan			chan;
  	struct list_head		free;
  	struct list_head		prepared;
  	struct list_head		queued;
  	struct list_head		active;
  	struct list_head		completed;
  	struct mpc_dma_tcd		*tcd;
  	dma_addr_t			tcd_paddr;

  	/* Settings for access to peripheral FIFO */
  	dma_addr_t			src_per_paddr;
  	u32				src_tcd_nunits;

  	u8				swidth;

  	dma_addr_t			dst_per_paddr;
  	u32				dst_tcd_nunits;

  	u8				dwidth;

  	/* Lock for this structure */
  	spinlock_t			lock;
  };
  
  struct mpc_dma {
  	struct dma_device		dma;
  	struct tasklet_struct		tasklet;
  	struct mpc_dma_chan		channels[MPC_DMA_CHANNELS];
  	struct mpc_dma_regs __iomem	*regs;
  	struct mpc_dma_tcd __iomem	*tcd;
  	int				irq;

  	int				irq2;

  	uint				error_status;

  	int				is_mpc8308;

  
  	/* Lock for error_status field in this structure */
  	spinlock_t			error_status_lock;
  };
  
  #define DRV_NAME	"mpc512x_dma"
  
  /* Convert struct dma_chan to struct mpc_dma_chan */
  static inline struct mpc_dma_chan *dma_chan_to_mpc_dma_chan(struct dma_chan *c)
  {
  	return container_of(c, struct mpc_dma_chan, chan);
  }
  
  /* Convert struct dma_chan to struct mpc_dma */
  static inline struct mpc_dma *dma_chan_to_mpc_dma(struct dma_chan *c)
  {
  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(c);

  	return container_of(mchan, struct mpc_dma, channels[c->chan_id]);
  }
  
  /*
   * Execute all queued DMA descriptors.
   *
   * Following requirements must be met while calling mpc_dma_execute():

   *	a) mchan->lock is acquired,
   *	b) mchan->active list is empty,
   *	c) mchan->queued list contains at least one entry.

   */
  static void mpc_dma_execute(struct mpc_dma_chan *mchan)
  {
  	struct mpc_dma *mdma = dma_chan_to_mpc_dma(&mchan->chan);
  	struct mpc_dma_desc *first = NULL;
  	struct mpc_dma_desc *prev = NULL;
  	struct mpc_dma_desc *mdesc;
  	int cid = mchan->chan.chan_id;

  	while (!list_empty(&mchan->queued)) {
  		mdesc = list_first_entry(&mchan->queued,
  						struct mpc_dma_desc, node);
  		/*
  		 * Grab either several mem-to-mem transfer descriptors
  		 * or one peripheral transfer descriptor,
  		 * don't mix mem-to-mem and peripheral transfer descriptors
  		 * within the same 'active' list.
  		 */
  		if (mdesc->will_access_peripheral) {
  			if (list_empty(&mchan->active))
  				list_move_tail(&mdesc->node, &mchan->active);
  			break;
  		} else {
  			list_move_tail(&mdesc->node, &mchan->active);
  		}
  	}

  
  	/* Chain descriptors into one transaction */
  	list_for_each_entry(mdesc, &mchan->active, node) {
  		if (!first)
  			first = mdesc;
  
  		if (!prev) {
  			prev = mdesc;
  			continue;
  		}
  
  		prev->tcd->dlast_sga = mdesc->tcd_paddr;
  		prev->tcd->e_sg = 1;
  		mdesc->tcd->start = 1;
  
  		prev = mdesc;
  	}

  	prev->tcd->int_maj = 1;
  
  	/* Send first descriptor in chain into hardware */
  	memcpy_toio(&mdma->tcd[cid], first->tcd, sizeof(struct mpc_dma_tcd));

  
  	if (first != prev)
  		mdma->tcd[cid].e_sg = 1;

  
  	if (mdma->is_mpc8308) {
  		/* MPC8308, no request lines, software initiated start */
  		out_8(&mdma->regs->dmassrt, cid);
  	} else if (first->will_access_peripheral) {
  		/* Peripherals involved, start by external request signal */
  		out_8(&mdma->regs->dmaserq, cid);
  	} else {
  		/* Memory to memory transfer, software initiated start */
  		out_8(&mdma->regs->dmassrt, cid);
  	}

  }
  
  /* Handle interrupt on one half of DMA controller (32 channels) */
  static void mpc_dma_irq_process(struct mpc_dma *mdma, u32 is, u32 es, int off)
  {
  	struct mpc_dma_chan *mchan;
  	struct mpc_dma_desc *mdesc;
  	u32 status = is | es;
  	int ch;
  
  	while ((ch = fls(status) - 1) >= 0) {
  		status &= ~(1 << ch);
  		mchan = &mdma->channels[ch + off];
  
  		spin_lock(&mchan->lock);

  		out_8(&mdma->regs->dmacint, ch + off);
  		out_8(&mdma->regs->dmacerr, ch + off);

  		/* Check error status */
  		if (es & (1 << ch))
  			list_for_each_entry(mdesc, &mchan->active, node)
  				mdesc->error = -EIO;
  
  		/* Execute queued descriptors */
  		list_splice_tail_init(&mchan->active, &mchan->completed);
  		if (!list_empty(&mchan->queued))
  			mpc_dma_execute(mchan);
  
  		spin_unlock(&mchan->lock);
  	}
  }
  
  /* Interrupt handler */
  static irqreturn_t mpc_dma_irq(int irq, void *data)
  {
  	struct mpc_dma *mdma = data;
  	uint es;
  
  	/* Save error status register */
  	es = in_be32(&mdma->regs->dmaes);
  	spin_lock(&mdma->error_status_lock);
  	if ((es & MPC_DMA_DMAES_VLD) && mdma->error_status == 0)
  		mdma->error_status = es;
  	spin_unlock(&mdma->error_status_lock);
  
  	/* Handle interrupt on each channel */

  	if (mdma->dma.chancnt > 32) {
  		mpc_dma_irq_process(mdma, in_be32(&mdma->regs->dmainth),

  					in_be32(&mdma->regs->dmaerrh), 32);

  	}

  	mpc_dma_irq_process(mdma, in_be32(&mdma->regs->dmaintl),
  					in_be32(&mdma->regs->dmaerrl), 0);

  	/* Schedule tasklet */
  	tasklet_schedule(&mdma->tasklet);
  
  	return IRQ_HANDLED;
  }

  /* process completed descriptors */

  static void mpc_dma_process_completed(struct mpc_dma *mdma)

  {

  	dma_cookie_t last_cookie = 0;
  	struct mpc_dma_chan *mchan;
  	struct mpc_dma_desc *mdesc;
  	struct dma_async_tx_descriptor *desc;
  	unsigned long flags;
  	LIST_HEAD(list);

  	int i;

  	for (i = 0; i < mdma->dma.chancnt; i++) {
  		mchan = &mdma->channels[i];
  
  		/* Get all completed descriptors */
  		spin_lock_irqsave(&mchan->lock, flags);
  		if (!list_empty(&mchan->completed))
  			list_splice_tail_init(&mchan->completed, &list);
  		spin_unlock_irqrestore(&mchan->lock, flags);
  
  		if (list_empty(&list))
  			continue;
  
  		/* Execute callbacks and run dependencies */
  		list_for_each_entry(mdesc, &list, node) {
  			desc = &mdesc->desc;

  			dmaengine_desc_get_callback_invoke(desc, NULL);

  
  			last_cookie = desc->cookie;
  			dma_run_dependencies(desc);
  		}
  
  		/* Free descriptors */
  		spin_lock_irqsave(&mchan->lock, flags);
  		list_splice_tail_init(&list, &mchan->free);

  		mchan->chan.completed_cookie = last_cookie;

  		spin_unlock_irqrestore(&mchan->lock, flags);
  	}
  }
  
  /* DMA Tasklet */
  static void mpc_dma_tasklet(unsigned long data)
  {
  	struct mpc_dma *mdma = (void *)data;
  	unsigned long flags;
  	uint es;

  	spin_lock_irqsave(&mdma->error_status_lock, flags);
  	es = mdma->error_status;
  	mdma->error_status = 0;
  	spin_unlock_irqrestore(&mdma->error_status_lock, flags);
  
  	/* Print nice error report */
  	if (es) {
  		dev_err(mdma->dma.dev,
  			"Hardware reported following error(s) on channel %u:
  ",
  						      MPC_DMA_DMAES_ERRCHN(es));
  
  		if (es & MPC_DMA_DMAES_GPE)
  			dev_err(mdma->dma.dev, "- Group Priority Error
  ");
  		if (es & MPC_DMA_DMAES_CPE)
  			dev_err(mdma->dma.dev, "- Channel Priority Error
  ");
  		if (es & MPC_DMA_DMAES_SAE)
  			dev_err(mdma->dma.dev, "- Source Address Error
  ");
  		if (es & MPC_DMA_DMAES_SOE)

  			dev_err(mdma->dma.dev, "- Source Offset Configuration Error
  ");

  		if (es & MPC_DMA_DMAES_DAE)

  			dev_err(mdma->dma.dev, "- Destination Address Error
  ");

  		if (es & MPC_DMA_DMAES_DOE)

  			dev_err(mdma->dma.dev, "- Destination Offset Configuration Error
  ");

  		if (es & MPC_DMA_DMAES_NCE)

  			dev_err(mdma->dma.dev, "- NBytes/Citter Configuration Error
  ");

  		if (es & MPC_DMA_DMAES_SGE)

  			dev_err(mdma->dma.dev, "- Scatter/Gather Configuration Error
  ");

  		if (es & MPC_DMA_DMAES_SBE)
  			dev_err(mdma->dma.dev, "- Source Bus Error
  ");
  		if (es & MPC_DMA_DMAES_DBE)
  			dev_err(mdma->dma.dev, "- Destination Bus Error
  ");
  	}

  	mpc_dma_process_completed(mdma);

  }
  
  /* Submit descriptor to hardware */
  static dma_cookie_t mpc_dma_tx_submit(struct dma_async_tx_descriptor *txd)
  {
  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(txd->chan);
  	struct mpc_dma_desc *mdesc;
  	unsigned long flags;
  	dma_cookie_t cookie;
  
  	mdesc = container_of(txd, struct mpc_dma_desc, desc);
  
  	spin_lock_irqsave(&mchan->lock, flags);
  
  	/* Move descriptor to queue */
  	list_move_tail(&mdesc->node, &mchan->queued);
  
  	/* If channel is idle, execute all queued descriptors */
  	if (list_empty(&mchan->active))
  		mpc_dma_execute(mchan);
  
  	/* Update cookie */

  	cookie = dma_cookie_assign(txd);

  	spin_unlock_irqrestore(&mchan->lock, flags);
  
  	return cookie;
  }
  
  /* Alloc channel resources */
  static int mpc_dma_alloc_chan_resources(struct dma_chan *chan)
  {
  	struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
  	struct mpc_dma_desc *mdesc;
  	struct mpc_dma_tcd *tcd;
  	dma_addr_t tcd_paddr;
  	unsigned long flags;
  	LIST_HEAD(descs);
  	int i;
  
  	/* Alloc DMA memory for Transfer Control Descriptors */
  	tcd = dma_alloc_coherent(mdma->dma.dev,
  			MPC_DMA_DESCRIPTORS * sizeof(struct mpc_dma_tcd),
  							&tcd_paddr, GFP_KERNEL);
  	if (!tcd)
  		return -ENOMEM;
  
  	/* Alloc descriptors for this channel */
  	for (i = 0; i < MPC_DMA_DESCRIPTORS; i++) {
  		mdesc = kzalloc(sizeof(struct mpc_dma_desc), GFP_KERNEL);
  		if (!mdesc) {

  			dev_notice(mdma->dma.dev,
  				"Memory allocation error. Allocated only %u descriptors
  ", i);

  			break;
  		}
  
  		dma_async_tx_descriptor_init(&mdesc->desc, chan);
  		mdesc->desc.flags = DMA_CTRL_ACK;
  		mdesc->desc.tx_submit = mpc_dma_tx_submit;
  
  		mdesc->tcd = &tcd[i];
  		mdesc->tcd_paddr = tcd_paddr + (i * sizeof(struct mpc_dma_tcd));
  
  		list_add_tail(&mdesc->node, &descs);
  	}
  
  	/* Return error only if no descriptors were allocated */
  	if (i == 0) {
  		dma_free_coherent(mdma->dma.dev,
  			MPC_DMA_DESCRIPTORS * sizeof(struct mpc_dma_tcd),
  								tcd, tcd_paddr);
  		return -ENOMEM;
  	}
  
  	spin_lock_irqsave(&mchan->lock, flags);
  	mchan->tcd = tcd;
  	mchan->tcd_paddr = tcd_paddr;
  	list_splice_tail_init(&descs, &mchan->free);
  	spin_unlock_irqrestore(&mchan->lock, flags);
  
  	/* Enable Error Interrupt */
  	out_8(&mdma->regs->dmaseei, chan->chan_id);
  
  	return 0;
  }
  
  /* Free channel resources */
  static void mpc_dma_free_chan_resources(struct dma_chan *chan)
  {
  	struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
  	struct mpc_dma_desc *mdesc, *tmp;
  	struct mpc_dma_tcd *tcd;
  	dma_addr_t tcd_paddr;
  	unsigned long flags;
  	LIST_HEAD(descs);
  
  	spin_lock_irqsave(&mchan->lock, flags);
  
  	/* Channel must be idle */
  	BUG_ON(!list_empty(&mchan->prepared));
  	BUG_ON(!list_empty(&mchan->queued));
  	BUG_ON(!list_empty(&mchan->active));
  	BUG_ON(!list_empty(&mchan->completed));
  
  	/* Move data */
  	list_splice_tail_init(&mchan->free, &descs);
  	tcd = mchan->tcd;
  	tcd_paddr = mchan->tcd_paddr;
  
  	spin_unlock_irqrestore(&mchan->lock, flags);
  
  	/* Free DMA memory used by descriptors */
  	dma_free_coherent(mdma->dma.dev,
  			MPC_DMA_DESCRIPTORS * sizeof(struct mpc_dma_tcd),
  								tcd, tcd_paddr);
  
  	/* Free descriptors */
  	list_for_each_entry_safe(mdesc, tmp, &descs, node)
  		kfree(mdesc);
  
  	/* Disable Error Interrupt */
  	out_8(&mdma->regs->dmaceei, chan->chan_id);
  }
  
  /* Send all pending descriptor to hardware */
  static void mpc_dma_issue_pending(struct dma_chan *chan)
  {
  	/*
  	 * We are posting descriptors to the hardware as soon as
  	 * they are ready, so this function does nothing.
  	 */
  }
  
  /* Check request completion status */
  static enum dma_status

  mpc_dma_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
  	       struct dma_tx_state *txstate)

  {

  	return dma_cookie_status(chan, cookie, txstate);

  }
  
  /* Prepare descriptor for memory to memory copy */
  static struct dma_async_tx_descriptor *
  mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
  					size_t len, unsigned long flags)
  {

  	struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);

  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
  	struct mpc_dma_desc *mdesc = NULL;
  	struct mpc_dma_tcd *tcd;
  	unsigned long iflags;
  
  	/* Get free descriptor */
  	spin_lock_irqsave(&mchan->lock, iflags);
  	if (!list_empty(&mchan->free)) {
  		mdesc = list_first_entry(&mchan->free, struct mpc_dma_desc,
  									node);
  		list_del(&mdesc->node);
  	}
  	spin_unlock_irqrestore(&mchan->lock, iflags);

  	if (!mdesc) {
  		/* try to free completed descriptors */
  		mpc_dma_process_completed(mdma);

  		return NULL;

  	}

  
  	mdesc->error = 0;

  	mdesc->will_access_peripheral = 0;

  	tcd = mdesc->tcd;
  
  	/* Prepare Transfer Control Descriptor for this transaction */
  	memset(tcd, 0, sizeof(struct mpc_dma_tcd));
  
  	if (IS_ALIGNED(src | dst | len, 32)) {
  		tcd->ssize = MPC_DMA_TSIZE_32;
  		tcd->dsize = MPC_DMA_TSIZE_32;
  		tcd->soff = 32;
  		tcd->doff = 32;

  	} else if (!mdma->is_mpc8308 && IS_ALIGNED(src | dst | len, 16)) {
  		/* MPC8308 doesn't support 16 byte transfers */

  		tcd->ssize = MPC_DMA_TSIZE_16;
  		tcd->dsize = MPC_DMA_TSIZE_16;
  		tcd->soff = 16;
  		tcd->doff = 16;
  	} else if (IS_ALIGNED(src | dst | len, 4)) {
  		tcd->ssize = MPC_DMA_TSIZE_4;
  		tcd->dsize = MPC_DMA_TSIZE_4;
  		tcd->soff = 4;
  		tcd->doff = 4;
  	} else if (IS_ALIGNED(src | dst | len, 2)) {
  		tcd->ssize = MPC_DMA_TSIZE_2;
  		tcd->dsize = MPC_DMA_TSIZE_2;
  		tcd->soff = 2;
  		tcd->doff = 2;
  	} else {
  		tcd->ssize = MPC_DMA_TSIZE_1;
  		tcd->dsize = MPC_DMA_TSIZE_1;
  		tcd->soff = 1;
  		tcd->doff = 1;
  	}
  
  	tcd->saddr = src;
  	tcd->daddr = dst;
  	tcd->nbytes = len;
  	tcd->biter = 1;
  	tcd->citer = 1;
  
  	/* Place descriptor in prepared list */
  	spin_lock_irqsave(&mchan->lock, iflags);
  	list_add_tail(&mdesc->node, &mchan->prepared);
  	spin_unlock_irqrestore(&mchan->lock, iflags);
  
  	return &mdesc->desc;
  }

  inline u8 buswidth_to_dmatsize(u8 buswidth)
  {
  	u8 res;
  
  	for (res = 0; buswidth > 1; buswidth /= 2)
  		res++;
  	return res;
  }

  static struct dma_async_tx_descriptor *
  mpc_dma_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 mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
  	struct mpc_dma_desc *mdesc = NULL;
  	dma_addr_t per_paddr;
  	u32 tcd_nunits;
  	struct mpc_dma_tcd *tcd;
  	unsigned long iflags;
  	struct scatterlist *sg;
  	size_t len;
  	int iter, i;
  
  	/* Currently there is no proper support for scatter/gather */
  	if (sg_len != 1)
  		return NULL;
  
  	if (!is_slave_direction(direction))
  		return NULL;
  
  	for_each_sg(sgl, sg, sg_len, i) {
  		spin_lock_irqsave(&mchan->lock, iflags);
  
  		mdesc = list_first_entry(&mchan->free,
  						struct mpc_dma_desc, node);
  		if (!mdesc) {
  			spin_unlock_irqrestore(&mchan->lock, iflags);
  			/* Try to free completed descriptors */
  			mpc_dma_process_completed(mdma);
  			return NULL;
  		}
  
  		list_del(&mdesc->node);
  
  		if (direction == DMA_DEV_TO_MEM) {
  			per_paddr = mchan->src_per_paddr;
  			tcd_nunits = mchan->src_tcd_nunits;
  		} else {
  			per_paddr = mchan->dst_per_paddr;
  			tcd_nunits = mchan->dst_tcd_nunits;
  		}
  
  		spin_unlock_irqrestore(&mchan->lock, iflags);
  
  		if (per_paddr == 0 || tcd_nunits == 0)
  			goto err_prep;
  
  		mdesc->error = 0;
  		mdesc->will_access_peripheral = 1;
  
  		/* Prepare Transfer Control Descriptor for this transaction */
  		tcd = mdesc->tcd;
  
  		memset(tcd, 0, sizeof(struct mpc_dma_tcd));

  		if (direction == DMA_DEV_TO_MEM) {
  			tcd->saddr = per_paddr;
  			tcd->daddr = sg_dma_address(sg);

  
  			if (!IS_ALIGNED(sg_dma_address(sg), mchan->dwidth))
  				goto err_prep;

  			tcd->soff = 0;

  			tcd->doff = mchan->dwidth;

  		} else {
  			tcd->saddr = sg_dma_address(sg);
  			tcd->daddr = per_paddr;

  
  			if (!IS_ALIGNED(sg_dma_address(sg), mchan->swidth))
  				goto err_prep;
  
  			tcd->soff = mchan->swidth;

  			tcd->doff = 0;
  		}

  		tcd->ssize = buswidth_to_dmatsize(mchan->swidth);
  		tcd->dsize = buswidth_to_dmatsize(mchan->dwidth);

  		if (mdma->is_mpc8308) {
  			tcd->nbytes = sg_dma_len(sg);

  			if (!IS_ALIGNED(tcd->nbytes, mchan->swidth))

  				goto err_prep;
  
  			/* No major loops for MPC8303 */
  			tcd->biter = 1;
  			tcd->citer = 1;
  		} else {
  			len = sg_dma_len(sg);

  			tcd->nbytes = tcd_nunits * tcd->ssize;

  			if (!IS_ALIGNED(len, tcd->nbytes))
  				goto err_prep;
  
  			iter = len / tcd->nbytes;
  			if (iter >= 1 << 15) {
  				/* len is too big */
  				goto err_prep;
  			}
  			/* citer_linkch contains the high bits of iter */
  			tcd->biter = iter & 0x1ff;
  			tcd->biter_linkch = iter >> 9;
  			tcd->citer = tcd->biter;
  			tcd->citer_linkch = tcd->biter_linkch;

  		}

  
  		tcd->e_sg = 0;
  		tcd->d_req = 1;
  
  		/* Place descriptor in prepared list */
  		spin_lock_irqsave(&mchan->lock, iflags);
  		list_add_tail(&mdesc->node, &mchan->prepared);
  		spin_unlock_irqrestore(&mchan->lock, iflags);
  	}
  
  	return &mdesc->desc;
  
  err_prep:
  	/* Put the descriptor back */
  	spin_lock_irqsave(&mchan->lock, iflags);
  	list_add_tail(&mdesc->node, &mchan->free);
  	spin_unlock_irqrestore(&mchan->lock, iflags);
  
  	return NULL;
  }

  inline bool is_buswidth_valid(u8 buswidth, bool is_mpc8308)
  {
  	switch (buswidth) {
  	case 16:
  		if (is_mpc8308)
  			return false;
  	case 1:
  	case 2:
  	case 4:
  	case 32:
  		break;
  	default:
  		return false;
  	}
  
  	return true;
  }

  static int mpc_dma_device_config(struct dma_chan *chan,
  				 struct dma_slave_config *cfg)

  {

  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);

  	struct mpc_dma *mdma = dma_chan_to_mpc_dma(&mchan->chan);

  	unsigned long flags;

  	/*
  	 * Software constraints:

  	 *  - only transfers between a peripheral device and memory are
  	 *     supported
  	 *  - transfer chunk sizes of 1, 2, 4, 16 (for MPC512x), and 32 bytes
  	 *     are supported, and, consequently, source addresses and
  	 *     destination addresses; must be aligned accordingly; furthermore,
  	 *     for MPC512x SoCs, the transfer size must be aligned on (chunk
  	 *     size * maxburst)
  	 *  - during the transfer, the RAM address is incremented by the size
  	 *     of transfer chunk
  	 *  - the peripheral port's address is constant during the transfer.

  	 */

  	if (!IS_ALIGNED(cfg->src_addr, cfg->src_addr_width) ||
  	    !IS_ALIGNED(cfg->dst_addr, cfg->dst_addr_width)) {

  		return -EINVAL;
  	}

  	if (!is_buswidth_valid(cfg->src_addr_width, mdma->is_mpc8308) ||
  	    !is_buswidth_valid(cfg->dst_addr_width, mdma->is_mpc8308))
  		return -EINVAL;

  	spin_lock_irqsave(&mchan->lock, flags);

  	mchan->src_per_paddr = cfg->src_addr;
  	mchan->src_tcd_nunits = cfg->src_maxburst;

  	mchan->swidth = cfg->src_addr_width;

  	mchan->dst_per_paddr = cfg->dst_addr;
  	mchan->dst_tcd_nunits = cfg->dst_maxburst;

  	mchan->dwidth = cfg->dst_addr_width;

  	/* Apply defaults */
  	if (mchan->src_tcd_nunits == 0)
  		mchan->src_tcd_nunits = 1;
  	if (mchan->dst_tcd_nunits == 0)
  		mchan->dst_tcd_nunits = 1;

  	spin_unlock_irqrestore(&mchan->lock, flags);

  	return 0;
  }

  static int mpc_dma_device_terminate_all(struct dma_chan *chan)
  {
  	struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
  	struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
  	unsigned long flags;

  	/* Disable channel requests */
  	spin_lock_irqsave(&mchan->lock, flags);

  	out_8(&mdma->regs->dmacerq, chan->chan_id);
  	list_splice_tail_init(&mchan->prepared, &mchan->free);
  	list_splice_tail_init(&mchan->queued, &mchan->free);
  	list_splice_tail_init(&mchan->active, &mchan->free);

  	spin_unlock_irqrestore(&mchan->lock, flags);

  	return 0;

  }

  static int mpc_dma_probe(struct platform_device *op)

  {

  	struct device_node *dn = op->dev.of_node;

  	struct device *dev = &op->dev;
  	struct dma_device *dma;
  	struct mpc_dma *mdma;
  	struct mpc_dma_chan *mchan;
  	struct resource res;
  	ulong regs_start, regs_size;
  	int retval, i;

  	u8 chancnt;

  
  	mdma = devm_kzalloc(dev, sizeof(struct mpc_dma), GFP_KERNEL);
  	if (!mdma) {

  		retval = -ENOMEM;
  		goto err;

  	}
  
  	mdma->irq = irq_of_parse_and_map(dn, 0);

  	if (!mdma->irq) {

  		dev_err(dev, "Error mapping IRQ!
  ");

  		retval = -EINVAL;
  		goto err;

  	}

  	if (of_device_is_compatible(dn, "fsl,mpc8308-dma")) {
  		mdma->is_mpc8308 = 1;
  		mdma->irq2 = irq_of_parse_and_map(dn, 1);

  		if (!mdma->irq2) {

  			dev_err(dev, "Error mapping IRQ!
  ");

  			retval = -EINVAL;
  			goto err_dispose1;

  		}
  	}

  	retval = of_address_to_resource(dn, 0, &res);
  	if (retval) {
  		dev_err(dev, "Error parsing memory region!
  ");

  		goto err_dispose2;

  	}
  
  	regs_start = res.start;

  	regs_size = resource_size(&res);

  
  	if (!devm_request_mem_region(dev, regs_start, regs_size, DRV_NAME)) {
  		dev_err(dev, "Error requesting memory region!
  ");

  		retval = -EBUSY;
  		goto err_dispose2;

  	}
  
  	mdma->regs = devm_ioremap(dev, regs_start, regs_size);
  	if (!mdma->regs) {
  		dev_err(dev, "Error mapping memory region!
  ");

  		retval = -ENOMEM;
  		goto err_dispose2;

  	}
  
  	mdma->tcd = (struct mpc_dma_tcd *)((u8 *)(mdma->regs)
  							+ MPC_DMA_TCD_OFFSET);

  	retval = request_irq(mdma->irq, &mpc_dma_irq, 0, DRV_NAME, mdma);

  	if (retval) {
  		dev_err(dev, "Error requesting IRQ!
  ");

  		retval = -EINVAL;
  		goto err_dispose2;

  	}

  	if (mdma->is_mpc8308) {

  		retval = request_irq(mdma->irq2, &mpc_dma_irq, 0,
  							DRV_NAME, mdma);

  		if (retval) {
  			dev_err(dev, "Error requesting IRQ2!
  ");

  			retval = -EINVAL;
  			goto err_free1;

  		}
  	}

  	spin_lock_init(&mdma->error_status_lock);
  
  	dma = &mdma->dma;
  	dma->dev = dev;

  	dma->device_alloc_chan_resources = mpc_dma_alloc_chan_resources;
  	dma->device_free_chan_resources = mpc_dma_free_chan_resources;
  	dma->device_issue_pending = mpc_dma_issue_pending;

  	dma->device_tx_status = mpc_dma_tx_status;

  	dma->device_prep_dma_memcpy = mpc_dma_prep_memcpy;

  	dma->device_prep_slave_sg = mpc_dma_prep_slave_sg;

  	dma->device_config = mpc_dma_device_config;
  	dma->device_terminate_all = mpc_dma_device_terminate_all;

  
  	INIT_LIST_HEAD(&dma->channels);
  	dma_cap_set(DMA_MEMCPY, dma->cap_mask);

  	dma_cap_set(DMA_SLAVE, dma->cap_mask);

  	if (mdma->is_mpc8308)
  		chancnt = MPC8308_DMACHAN_MAX;
  	else
  		chancnt = MPC512x_DMACHAN_MAX;
  
  	for (i = 0; i < chancnt; i++) {

  		mchan = &mdma->channels[i];
  
  		mchan->chan.device = dma;

  		dma_cookie_init(&mchan->chan);

  
  		INIT_LIST_HEAD(&mchan->free);
  		INIT_LIST_HEAD(&mchan->prepared);
  		INIT_LIST_HEAD(&mchan->queued);
  		INIT_LIST_HEAD(&mchan->active);
  		INIT_LIST_HEAD(&mchan->completed);
  
  		spin_lock_init(&mchan->lock);
  		list_add_tail(&mchan->chan.device_node, &dma->channels);
  	}
  
  	tasklet_init(&mdma->tasklet, mpc_dma_tasklet, (unsigned long)mdma);
  
  	/*
  	 * Configure DMA Engine:
  	 * - Dynamic clock,
  	 * - Round-robin group arbitration,
  	 * - Round-robin channel arbitration.
  	 */

  	if (mdma->is_mpc8308) {
  		/* MPC8308 has 16 channels and lacks some registers */
  		out_be32(&mdma->regs->dmacr, MPC_DMA_DMACR_ERCA);
  
  		/* enable snooping */
  		out_be32(&mdma->regs->dmagpor, MPC_DMA_DMAGPOR_SNOOP_ENABLE);
  		/* Disable error interrupts */
  		out_be32(&mdma->regs->dmaeeil, 0);
  
  		/* Clear interrupts status */
  		out_be32(&mdma->regs->dmaintl, 0xFFFF);
  		out_be32(&mdma->regs->dmaerrl, 0xFFFF);
  	} else {

  		out_be32(&mdma->regs->dmacr, MPC_DMA_DMACR_EDCG |

  						MPC_DMA_DMACR_ERGA |
  						MPC_DMA_DMACR_ERCA);

  
  		/* Disable hardware DMA requests */
  		out_be32(&mdma->regs->dmaerqh, 0);
  		out_be32(&mdma->regs->dmaerql, 0);
  
  		/* Disable error interrupts */
  		out_be32(&mdma->regs->dmaeeih, 0);
  		out_be32(&mdma->regs->dmaeeil, 0);
  
  		/* Clear interrupts status */
  		out_be32(&mdma->regs->dmainth, 0xFFFFFFFF);
  		out_be32(&mdma->regs->dmaintl, 0xFFFFFFFF);
  		out_be32(&mdma->regs->dmaerrh, 0xFFFFFFFF);
  		out_be32(&mdma->regs->dmaerrl, 0xFFFFFFFF);
  
  		/* Route interrupts to IPIC */
  		out_be32(&mdma->regs->dmaihsa, 0);
  		out_be32(&mdma->regs->dmailsa, 0);

  	}

  
  	/* Register DMA engine */
  	dev_set_drvdata(dev, mdma);
  	retval = dma_async_device_register(dma);

  	if (retval)
  		goto err_free2;

  	/* Register with OF helpers for DMA lookups (nonfatal) */
  	if (dev->of_node) {
  		retval = of_dma_controller_register(dev->of_node,
  						of_dma_xlate_by_chan_id, mdma);
  		if (retval)
  			dev_warn(dev, "Could not register for OF lookup
  ");
  	}
  
  	return 0;

  
  err_free2:
  	if (mdma->is_mpc8308)
  		free_irq(mdma->irq2, mdma);
  err_free1:
  	free_irq(mdma->irq, mdma);
  err_dispose2:
  	if (mdma->is_mpc8308)
  		irq_dispose_mapping(mdma->irq2);
  err_dispose1:
  	irq_dispose_mapping(mdma->irq);
  err:
  	return retval;

  }

  static int mpc_dma_remove(struct platform_device *op)

  {
  	struct device *dev = &op->dev;
  	struct mpc_dma *mdma = dev_get_drvdata(dev);

  	if (dev->of_node)
  		of_dma_controller_free(dev->of_node);

  	dma_async_device_unregister(&mdma->dma);

  	if (mdma->is_mpc8308) {
  		free_irq(mdma->irq2, mdma);
  		irq_dispose_mapping(mdma->irq2);
  	}
  	free_irq(mdma->irq, mdma);

  	irq_dispose_mapping(mdma->irq);

  	tasklet_kill(&mdma->tasklet);

  
  	return 0;
  }

  static const struct of_device_id mpc_dma_match[] = {

  	{ .compatible = "fsl,mpc5121-dma", },

  	{ .compatible = "fsl,mpc8308-dma", },

  	{},
  };

  MODULE_DEVICE_TABLE(of, mpc_dma_match);

  static struct platform_driver mpc_dma_driver = {

  	.probe		= mpc_dma_probe,

  	.remove		= mpc_dma_remove,

  	.driver = {
  		.name = DRV_NAME,

  		.of_match_table	= mpc_dma_match,

  	},
  };

  module_platform_driver(mpc_dma_driver);

  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Piotr Ziecik <kosmo@semihalf.com>");