Subject: [PATCH 06/13] DMAENGINE: driver for the ARM PL080/PL081 PrimeCells

From: [email-masked] (Viresh KUMAR)
Date: Mon, 14 Jun 2010 11:32:54 +0530

Linus,

I haven't reviewed it completely. Will do it in some time.

On 6/11/2010 8:57 PM, Linus WALLEIJ wrote:

[snip...]

> diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
> new file mode 100644
> index 0000000..50531fa
> --- /dev/null
> +++ b/drivers/dma/amba-pl08x.c
> @@ -0,0 +1,1925 @@
> +/*
> + * Copyright (c) 2006 ARM Ltd.
> + * Copyright (c) 2010 ST-Ericsson SA
> + *
> + * 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.
> + *
> + * 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., 59
> + * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
> + *
> + * The full GNU General Public License is iin this distribution in the
> + * file called COPYING.
> + *
> + * Documentation: ARM DDI 0196G == PL080
> + * Documentation: ARM DDI 0218E	== PL081
> + *
> + * PL080 & PL081 both have 16 sets of DMA signals. They differ in the number
> + * of channels which may be in use at once. Also PL080 has a dual bus master,
> + * PL081 has a single master.
> + *
> + * Memory to peripheral transfer may be visualized as
> + *	Get data from memory to DMAC
> + *	Until no data left
> + *		On burst request from peripheral
> + *			Destination burst from DMAC to peripheral
> + *			Clear burst request
> + *	Raise terminal count interrupt
> + *
> + * For peripherals with a FIFO:
> + * Source      burst size == half the depth of the peripheral FIFO
> + * Destination burst size == width of the peripheral FIFO
> + *

I didn't get it completely, why burst depends upon width of peripheral FIFO.

> + * (Bursts are irrelevant for mem to mem transfers - there are no burst
> + * signals)

I agree that there are no request lines from memories but still we can program
them with burst in order to faster the transfer. This burst feature is
automatically handled by DMA.

> + *
> + * ASSUMES default (little) endianness for DMA transfers
> + *
> + * Only DMAC flow control is implemented
> + *
> + * Global TODO:
> + * - Break out common code from arch/arm/mach-s3c64xx and share
> + */
> +#include <linux/device.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/interrupt.h>
> +#include <linux/slab.h>
> +#include <linux/dmapool.h>
> +#include <linux/amba/bus.h>
> +#include <linux/dmaengine.h>
> +#include <linux/amba/pl08x.h>
> +#include <linux/amba/dma.h>
> +
> +#include <asm/hardware/pl080.h>
> +#include <asm/dma.h>
> +#include <asm/mach/dma.h>
> +#include <asm/atomic.h>
> +#include <asm/processor.h>
> +#include <asm/cacheflush.h>
> +
> +#define DRIVER_NAME	"pl08xdmac"
> +
> +/**
> + * struct vendor_data - vendor-specific config parameters
> + * for PL08x derivates
> + * @name: the name of this specific variant
> + * @channels: the number of channels available in this variant
> + */
> +struct vendor_data {
> +	char *name;
> +	u8 channels;
> +};
> +
> +/*
> + * PL08X private data structures
> + * An LLI struct - see pl08x TRM
> + * Note that next uses bit[0] as a bus bit,
> + * start & end do not - their bus bit info
> + * is in cctl
> + */
> +struct lli {
> +	dma_addr_t src;
> +	dma_addr_t dst;
> +	dma_addr_t next;
> +	u32 cctl;
> +};
> +
> +/**
> + * struct pl08x_driver_data - the local state holder for the PL08x
> + * @base: virtual memory base (remapped) for the PL08x
> + * @adev: the corresponding AMBA (PrimeCell) bus entry
> + * @vd: vendor data for this PL08x variant
> + * @pd: platform data passed in from the platform/machine
> + * @phy_chans: array of data for the physical channels
> + * @pool: a pool for the LLI descriptors
> + * @pool_ctr: counter of LLIs in the pool
> + * @max_num_llis: maximum number of LLIs, i.e. longest linked transfer
> + * length, submitted so far

What is the significance of this field? What it is used for?

> + * @lock: a spinlock for this struct
> + */
> +struct pl08x_driver_data {
> +	void __iomem *base;
> +	struct amba_device *adev;
> +	struct vendor_data *vd;
> +	struct pl08x_platform_data *pd;
> +	struct pl08x_phy_chan *phy_chans;
> +	struct dma_pool *pool;
> +	int pool_ctr;
> +	int max_num_llis;
> +	spinlock_t lock;
> +};
> +
> +#ifdef MODULE
> +
> +# error "AMBA PL08X DMA CANNOT BE COMPILED AS A LOADABLE MODULE AT PRESENT"
> +
> +/*
> +	a) Some devices might make use of DMA during boot
> +	   (esp true for DMAENGINE implementation)
> +	b) Memory allocation will need much more attention
> +	   before load/unload can be supported
> + */
> +#endif
> +
> +/*
> + * PL08X specific defines
> + */
> +
> +/*
> + * Memory boundaries: the manual for PL08x says that the controller
> + * cannot read past a 1KiB boundary, so these defines are used to
> + * create transfer LLIs that do not cross such boundaries.
> + */
> +#define PL08X_BOUNDARY_SHIFT		(10)	/* 1KB 0x400 */
> +#define PL08X_BOUNDARY_SIZE		(1 << PL08X_BOUNDARY_SHIFT)
> +
> +/* Minimum period between work queue runs */
> +#define PL08X_WQ_PERIODMIN	20
> +
> +/* Size (bytes) of each LLI buffer allocated for one transfer */
> +# define PL08X_LLI_TSFR_SIZE	0x2000
> +
> +/* Maximimum times we call dma_pool_alloc on this pool without freeing */
> +#define PL08X_MAX_ALLOCS	0x40
> +#define MAX_NUM_TSFR_LLIS	(PL08X_LLI_TSFR_SIZE/sizeof(struct lli))
> +#define PL08X_ALIGN		8
> +
> +static inline struct pl08x_dma_chan *to_pl08x_chan(struct dma_chan *chan)
> +{
> +	return container_of(chan, struct pl08x_dma_chan, chan);
> +}
> +
> +/*
> + * Physical channel handling
> + */
> +
> +/* Whether a certain channel is busy or not */
> +static int pl08x_phy_channel_busy(struct pl08x_phy_chan *ch)
> +{
> +	unsigned int val;
> +
> +	val = readl(ch->base + PL080_CH_CONFIG);
> +	return val & PL080_CONFIG_ACTIVE;
> +}
> +
> +/*
> + * Set the initial DMA register values i.e. those for the first LLI
> + * The next lli pointer and the configuration interrupt bit have
> + * been set when the LLIs were constructed
> + */
> +static void pl08x_set_cregs(struct pl08x_driver_data *pl08x,
> +			    struct pl08x_phy_chan *ch)
> +{
> +	u32 val;
> +
> +	/* Wait for channel inactive */
> +	val = readl(ch->base + PL080_CH_CONFIG);
> +	while (val & PL080_CONFIG_ACTIVE)
> +		val = readl(ch->base + PL080_CH_CONFIG);

can we use pl08x_phy_channel_busy() instead of above code?

> +
> +	dev_vdbg(&pl08x->adev->dev,
> +		"WRITE channel %d: csrc=%08x, cdst=%08x, "
> +		 "cctl=%08x, clli=%08x, ccfg=%08x\n",
> +		ch->id,
> +		ch->csrc,
> +		ch->cdst,
> +		ch->cctl,
> +		ch->clli,
> +		ch->ccfg);
> +
> +	writel(ch->csrc, ch->base + PL080_CH_SRC_ADDR);
> +	writel(ch->cdst, ch->base + PL080_CH_DST_ADDR);
> +	writel(ch->clli, ch->base + PL080_CH_LLI);
> +	writel(ch->cctl, ch->base + PL080_CH_CONTROL);
> +	writel(ch->ccfg, ch->base + PL080_CH_CONFIG);
> +	mb();
> +}
> +
> +static inline void pl08x_config_phychan_for_txd(struct pl08x_dma_chan *plchan)
> +{
> +	struct pl08x_channel_data *cd = plchan->cd;
> +	struct pl08x_phy_chan *phychan = plchan->phychan;
> +	struct pl08x_txd *txd = plchan->at;
> +
> +	/* Copy the basic control register calculated at transfer config */
> +	phychan->csrc = txd->csrc;
> +	phychan->cdst = txd->cdst;
> +	phychan->clli = txd->clli;
> +	phychan->cctl = txd->cctl;
> +
> +	/* Assign the signal to the proper control registers */
> +	phychan->ccfg = cd->ccfg;
> +	phychan->ccfg &= ~PL080_CONFIG_SRC_SEL_MASK;
> +	phychan->ccfg &= ~PL080_CONFIG_DST_SEL_MASK;
> +	/* If it wasn't set from AMBA, ignore it */
> +	if (txd->direction == DMA_TO_DEVICE)
> +		/* Select signal as destination */
> +		phychan->ccfg |=
> +			(phychan->signal << PL080_CONFIG_DST_SEL_SHIFT);
> +	else if (txd->direction == DMA_FROM_DEVICE)
> +		/* Select signal as source */
> +		phychan->ccfg |=
> +			(phychan->signal << PL080_CONFIG_SRC_SEL_SHIFT);
> +	/* Always enable error interrupts */
> +	phychan->ccfg |= PL080_CONFIG_ERR_IRQ_MASK;
> +	/* Always enable terminal interrupts */
> +	phychan->ccfg |= PL080_CONFIG_TC_IRQ_MASK;
> +}
> +
> +/*
> + * Enable the DMA channel
> + * Assumes all other configuration bits have been set
> + * as desired before this code is called
> + */
> +static void pl08x_enable_phy_chan(struct pl08x_driver_data *pl08x,
> +				  struct pl08x_phy_chan *ch)
> +{
> +	u32 val;
> +
> +	/*
> +	 * Do not access config register until channel shows as disabled
> +	 */
> +	while (readl(pl08x->base + PL080_EN_CHAN) & (1 << ch->id))
> +		;
> +
> +	/*
> +	 * Do not access config register until channel shows as inactive
> +	 */
> +	val = readl(ch->base + PL080_CH_CONFIG);
> +	while ((val & PL080_CONFIG_ACTIVE) || (val & PL080_CONFIG_ENABLE))
> +		val = readl(ch->base + PL080_CH_CONFIG);

above 3 fns are always called in order, i.e. pl08x_enable_phy_chan will
be called after pl08x_set_cregs, so we may not require these checks
here. Is my understanding correct??

> +
> +	writel(val | PL080_CONFIG_ENABLE, ch->base + PL080_CH_CONFIG);
> +	mb();
> +}
> +
> +/*
> + * Overall DMAC remains enabled always.
> + *
> + * Disabling individual channels could lose data.
> + *
> + * Disable the peripheral DMA after disabling the DMAC
> + * in order to allow the DMAC FIFO to drain, and
> + * hence allow the channel to show inactive
> + *
> + */
> +static void pl08x_pause_phy_chan(struct pl08x_phy_chan *ch)
> +{
> +	u32 val;
> +
> +	/* Set the HALT bit and wait for the FIFO to drain */
> +	val = readl(ch->base + PL080_CH_CONFIG);
> +	val |= PL080_CONFIG_HALT;
> +	writel(val, ch->base + PL080_CH_CONFIG);
> +
> +	/* Wait for channel inactive */
> +	val = readl(ch->base + PL080_CH_CONFIG);
> +	while (val & PL080_CONFIG_ACTIVE)
> +		val = readl(ch->base + PL080_CH_CONFIG);

can we use pl08x_phy_channel_busy() instead of above code?
Please check everywhere.

> +
> +	mb();
> +
> +	return;

return not required!!

> +}
> +
> +static void pl08x_resume_phy_chan(struct pl08x_phy_chan *ch)

can these small fns be made inline???

> +{
> +	u32 val;
> +
> +	/* Clear the HALT bit */
> +	val = readl(ch->base + PL080_CH_CONFIG);
> +	val &= ~PL080_CONFIG_HALT;
> +	writel(val, ch->base + PL080_CH_CONFIG);
> +	mb();
> +
> +	return;
> +}
> +
> +
> +/* Stops the channel */
> +static void pl08x_stop_phy_chan(struct pl08x_phy_chan *ch)
> +{
> +	u32 val;
> +
> +	pl08x_pause_phy_chan(ch);
> +
> +	/* Disable channel */
> +	val = readl(ch->base + PL080_CH_CONFIG);
> +	val &= ~PL080_CONFIG_ENABLE;
> +	writel(val, ch->base + PL080_CH_CONFIG);
> +	mb();
> +
> +	return;

same here. return not required.

> +}
> +
> +static inline u32 get_bytes_in_cctl(u32 cctl)
> +{
> +	/* The source width defines the number of bytes */
> +	u32 bytes = cctl & PL080_CONTROL_TRANSFER_SIZE_MASK;
> +
> +	switch ((cctl >> 18) & 3) {

better to use Macros instead of magic numbers here!!!

> +	case PL080_WIDTH_8BIT:
> +		break;
> +	case PL080_WIDTH_16BIT:
> +		bytes *= 2;
> +		break;
> +	case PL080_WIDTH_32BIT:
> +		bytes *= 4;
> +		break;
> +	}
> +	return bytes;
> +}
> +
> +static u32 pl08x_getbytes_phy_chan(struct pl08x_phy_chan *ch)
> +{
> +	u32 bytes;
> +
> +	/* FIXME: follow all queued transactions */
> +	bytes = get_bytes_in_cctl(readl(ch->base + PL080_CH_CONTROL));
> +	/* TODO: follow the LLI to see the sum summarum */
> +	return bytes;
> +}
> +
> +/*
> + * Allocate a physical channel for a virtual channel
> + */
> +static struct pl08x_phy_chan *
> +pl08x_get_phy_channel(struct pl08x_driver_data *pl08x,
> +		      struct pl08x_dma_chan *virt_chan)
> +{
> +	struct pl08x_phy_chan *ch = NULL;
> +	unsigned long flags;
> +	int i;
> +
> +	/*
> +	 * Try to locate a physical channel to be used for
> +	 * this transfer. If all are taken return NULL and
> +	 * the requester will have to cope by using some fallback
> +	 * PIO mode or retrying later.
> +	 */
> +	for (i = 0; i < pl08x->vd->channels; i++) {
> +		ch = &pl08x->phy_chans[i];
> +
> +		spin_lock_irqsave(&ch->lock, flags);
> +
> +		if (!ch->serving) {
> +			ch->serving = virt_chan;
> +			ch->signal = -1;
> +			spin_unlock_irqrestore(&ch->lock, flags);
> +			break;
> +		}
> +
> +		spin_unlock_irqrestore(&ch->lock, flags);
> +	}
> +
> +	if (i == pl08x->vd->channels) {
> +		/* No physical channel available, cope with it */
> +		return NULL;
> +	}
> +
> +	return ch;
> +}
> +
> +static inline void pl08x_put_phy_channel(struct pl08x_driver_data *pl08x,
> +					 struct pl08x_phy_chan *ch)
> +{
> +	unsigned long flags;
> +
> +	/* Stop the channel and clear its interrupts */
> +	pl08x_stop_phy_chan(ch);
> +	writel((1 << ch->id), pl08x->base + PL080_ERR_CLEAR);
> +	writel((1 << ch->id), pl08x->base + PL080_TC_CLEAR);
> +
> +	/* Mark it as free */
> +	spin_lock_irqsave(&ch->lock, flags);
> +	ch->serving = NULL;
> +	ch->signal = -1;
> +	spin_unlock_irqrestore(&ch->lock, flags);
> +}
> +
> +/*
> + * LLI handling
> + */
> +
> +static inline unsigned int pl08x_get_bytes_for_cctl(unsigned int coded)
> +{
> +	switch (coded) {
> +	case PL080_WIDTH_8BIT:
> +		return 1;
> +	case PL080_WIDTH_16BIT:
> +		return 2;
> +	case PL080_WIDTH_32BIT:
> +		return 4;
> +	default:
> +		break;
> +	}
> +	BUG();
> +	return 0;
> +}
> +
> +static inline u32 pl08x_cctl_bits(u32 cctl,
> +				  u8 srcwidth,
> +				  u8 dstwidth,
> +				  u32 tsize)

Not sure, if we should write above function prototype in just 2 lines,
or is it okay to write it the way it is written.

> +{
> +	u32 retbits = cctl;
> +
> +	/* Remove all src, dst and transfersize bits */
> +	retbits &= ~PL080_CONTROL_DWIDTH_MASK;
> +	retbits &= ~PL080_CONTROL_SWIDTH_MASK;
> +	retbits &= ~PL080_CONTROL_TRANSFER_SIZE_MASK;
> +
> +	/* Then set the bits according to the parameters */
> +	switch(srcwidth) {
> +	case 1:
> +		retbits |= PL080_WIDTH_8BIT << PL080_CONTROL_SWIDTH_SHIFT;
> +		break;
> +	case 2:
> +		retbits |= PL080_WIDTH_16BIT << PL080_CONTROL_SWIDTH_SHIFT;
> +		break;
> +	case 4:
> +		retbits |= PL080_WIDTH_32BIT << PL080_CONTROL_SWIDTH_SHIFT;
> +		break;
> +	default:
> +		BUG();
> +		break;
> +	}
> +
> +	switch(dstwidth) {
> +	case 1:
> +		retbits |= PL080_WIDTH_8BIT << PL080_CONTROL_DWIDTH_SHIFT;
> +		break;
> +	case 2:
> +		retbits |= PL080_WIDTH_16BIT << PL080_CONTROL_DWIDTH_SHIFT;
> +		break;
> +	case 4:
> +		retbits |= PL080_WIDTH_32BIT << PL080_CONTROL_DWIDTH_SHIFT;
> +		break;
> +	default:
> +		BUG();
> +		break;
> +	}
> +
> +	retbits |= tsize << PL080_CONTROL_TRANSFER_SIZE_SHIFT;
> +	return retbits;
> +}
> +
> +/*
> + * Autoselect a master bus to use for the transfer
> + * this prefers the destination bus if both available
> + * if fixed address on one bus the other will be chosen
> + */
> +void pl08x_choose_master_bus(struct pl08x_bus_data *src_bus,
> +	struct pl08x_bus_data *dst_bus, struct pl08x_bus_data **mbus,
> +	struct pl08x_bus_data **sbus, u32 cctl)
> +{
> +	if (!cctl & PL080_CONTROL_DST_INCR) {
> +		*mbus = src_bus;
> +		*sbus = dst_bus;
> +	} else if (!cctl & PL080_CONTROL_SRC_INCR) {
> +		*mbus = dst_bus;
> +		*sbus = src_bus;
> +	} else {
> +		if (dst_bus->buswidth == 4) {
> +			*mbus = dst_bus;
> +			*sbus = src_bus;
> +		} else if (src_bus->buswidth == 4) {
> +			*mbus = src_bus;
> +			*sbus = dst_bus;
> +		} else if (dst_bus->buswidth == 2) {
> +			*mbus = dst_bus;
> +			*sbus = src_bus;
> +		} else if (src_bus->buswidth == 2) {
> +			*mbus = src_bus;
> +			*sbus = dst_bus;
> +		} else {
> +			/* src_bus->buswidth == 1 */
> +			*mbus = dst_bus;
> +			*sbus = src_bus;
> +		}
> +	}
> +}
> +
> +/*
> + * Fills in one LLI for a certain transfer descriptor
> + * and advance the counter
> + */
> +int pl08x_fill_lli_for_desc(struct pl08x_driver_data *pl08x,
> +			    struct pl08x_txd *txd, int num_llis, int len,
> +			    u32 cctl, u32 *remainder)
> +{
> +	struct lli *llis_va = (struct lli *)(txd->llis_va);
> +	struct lli *llis_bus = (struct lli *)(txd->llis_bus);
> +
> +	BUG_ON(num_llis >= MAX_NUM_TSFR_LLIS);
> +
> +	llis_va[num_llis].cctl		= cctl;
> +	llis_va[num_llis].src		= txd->srcbus.addr;
> +	llis_va[num_llis].dst		= txd->dstbus.addr;
> +	/*
> +	 * The bus bit is added to the next lli's address
> +	 */
> +	llis_va[num_llis].next =
> +		(dma_addr_t)((u32) &(llis_bus[num_llis + 1])
> +			     | pl08x->pd->bus_bit_lli);
> +
> +	if (cctl & PL080_CONTROL_SRC_INCR)
> +		txd->srcbus.addr += len;
> +	if (cctl & PL080_CONTROL_DST_INCR)
> +		txd->dstbus.addr += len;
> +
> +	*remainder -= len;
> +
> +	return num_llis + 1;
> +}
> +
> +/*
> + * Return number of bytes to fill to boundary, or len
> + */
> +static inline u32 pl08x_pre_boundary(u32 addr, u32 len)
> +{
> +	u32 boundary;
> +
> +	boundary = ((addr >> PL08X_BOUNDARY_SHIFT) + 1)
> +		<< PL08X_BOUNDARY_SHIFT;
> +
> +	if (boundary < addr + len)
> +		return boundary - addr;
> +	else
> +		return len;
> +}
> +
> +/*
> + * This fills in the table of LLIs for the transfer descriptor
> + * Note that we assume we never have to change the burst sizes
> + * Return 0 for error
> + */
> +static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x,
> +			      struct pl08x_txd *txd)
> +{
> +	struct pl08x_channel_data *cd = txd->cd;
> +	struct pl08x_bus_data *mbus, *sbus;
> +	u32 remainder;
> +	int num_llis = 0;
> +	u32 cctl;
> +	int max_bytes_per_lli;
> +	int total_bytes = 0;
> +	struct lli *llis_va;
> +	struct lli *llis_bus;
> +
> +	if (!txd) {
> +		dev_err(&pl08x->adev->dev, "%s no descriptor\n", __func__);
> +		return 0;
> +	}
> +
> +	txd->llis_va = dma_pool_alloc(pl08x->pool, GFP_KERNEL,
> +				      &txd->llis_bus);
> +	if (!txd->llis_va) {
> +		dev_err(&pl08x->adev->dev, "%s no memory for llis\n", __func__);
> +		return 0;
> +	}
> +
> +	pl08x->pool_ctr++;
> +
> +	/*
> +	 * Initialize bus values for this transfer
> +	 * from the passed optimal values
> +	 */
> +	if (!cd) {
> +		dev_err(&pl08x->adev->dev, "%s no channel data\n", __func__);
> +		return 0;
> +	}
> +
> +	/* Get the default CCTL from the platform data */
> +	cctl = cd->cctl;
> +
> +	/* Find maximum width of the source bus */
> +	txd->srcbus.maxwidth =
> +		pl08x_get_bytes_for_cctl((cctl & PL080_CONTROL_SWIDTH_MASK) >>
> +				       PL080_CONTROL_SWIDTH_SHIFT);
> +
> +	/* Find maximum width of the destination bus */
> +	txd->dstbus.maxwidth =
> +		pl08x_get_bytes_for_cctl((cctl & PL080_CONTROL_DWIDTH_MASK) >>
> +				       PL080_CONTROL_DWIDTH_SHIFT);
> +
> +	/* Set up the bus widths to the maximum */
> +	txd->srcbus.buswidth = txd->srcbus.maxwidth;
> +	txd->dstbus.buswidth = txd->dstbus.maxwidth;
> +	dev_vdbg(&pl08x->adev->dev,
> +		 "%s source bus is %d bytes wide, dest bus is %d bytes wide\n",
> +		 __func__, txd->srcbus.buswidth, txd->dstbus.buswidth);
> +
> +
> +	/*
> +	 * bytes transferred == tsize * MIN(buswidths), not max(buswidths)
> +	 */
> +	max_bytes_per_lli = min(txd->srcbus.buswidth, txd->dstbus.buswidth) *
> +		PL080_CONTROL_TRANSFER_SIZE_MASK;
> +	dev_vdbg(&pl08x->adev->dev,
> +		 "%s max bytes per lli = %d\n",
> +		 __func__, max_bytes_per_lli);
> +
> +	/* We need to count this down to zero */
> +	remainder = txd->len;
> +	dev_vdbg(&pl08x->adev->dev,
> +		 "%s remainder = %d\n",
> +		 __func__, remainder);
> +
> +	/*
> +	 * Choose bus to align to
> +	 * - prefers destination bus if both available
> +	 * - if fixed address on one bus chooses other
> +	 */
> +	pl08x_choose_master_bus(&txd->srcbus,
> +		&txd->dstbus, &mbus, &sbus, cctl);
> +
> +	if (txd->len < mbus->buswidth) {
> +		/*
> +		 * Less than a bus width available
> +		 * - send as single bytes
> +		 */
> +		while (remainder) {
> +			dev_vdbg(&pl08x->adev->dev,
> +				 "%s single byte LLIs for a transfer of less than a bus width (remain %08x)\n",
> +				 __func__, remainder);
> +			cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
> +			num_llis =
> +				pl08x_fill_lli_for_desc(pl08x, txd, num_llis, 1,
> +					cctl, &remainder);
> +			total_bytes++;
> +		}
> +	} else {
> +		/*
> +		 *  Make one byte LLIs until master bus is aligned
> +		 *  - slave will then be aligned also
> +		 */
> +		while ((mbus->addr) % (mbus->buswidth)) {
> +			dev_vdbg(&pl08x->adev->dev,
> +				"%s adjustment lli for less than bus width (remain %08x)\n",
> +				 __func__, remainder);
> +			cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
> +			num_llis = pl08x_fill_lli_for_desc
> +				(pl08x, txd, num_llis, 1, cctl, &remainder);
> +			total_bytes++;
> +		}
> +
> +		/*
> +		 *  Master now aligned
> +		 * - if slave is not then we must set its width down
> +		 */
> +		if (sbus->addr % sbus->buswidth) {
> +			dev_dbg(&pl08x->adev->dev,
> +				"%s set down bus width to one byte\n",
> +				 __func__);
> +
> +			sbus->buswidth = 1;
> +		}
> +
> +		/*
> +		 * Make largest possible LLIs until less than one bus width left
> +		 */
> +		while (remainder > (mbus->buswidth - 1)) {
> +			int lli_len, target_len;
> +			int tsize;
> +			int odd_bytes;
> +
> +			/*
> +			 * If enough left try to send max possible,
> +			 * otherwise try to send the remainder
> +			 */
> +			target_len = remainder;
> +			if (remainder > max_bytes_per_lli)
> +				target_len = max_bytes_per_lli;
> +
> +			/*
> +			 * Set bus lengths for incrementing busses
> +			 * to number of bytes which fill to next memory
> +			 * boundary
> +			 */
> +			if (cctl & PL080_CONTROL_SRC_INCR)
> +				txd->srcbus.fill_bytes =
> +					pl08x_pre_boundary(
> +						txd->srcbus.addr,
> +						remainder);
> +			else
> +				txd->srcbus.fill_bytes =
> +					max_bytes_per_lli;
> +
> +			if (cctl & PL080_CONTROL_DST_INCR)
> +				txd->dstbus.fill_bytes =
> +					pl08x_pre_boundary(
> +						txd->dstbus.addr,
> +						remainder);
> +			else
> +				txd->dstbus.fill_bytes =
> +						max_bytes_per_lli;
> +
> +			/*
> +			 *  Find the nearest
> +			 */
> +			lli_len	= min(txd->srcbus.fill_bytes,
> +				txd->dstbus.fill_bytes);
> +
> +			BUG_ON(lli_len > remainder);
> +
> +			if (lli_len <= 0) {
> +				dev_err(&pl08x->adev->dev,
> +					"%s lli_len is %d, <= 0\n",
> +						__func__, lli_len);
> +				return 0;
> +			}
> +
> +			if (lli_len == target_len) {
> +				/*
> +				 * Can send what we wanted
> +				 */
> +				/*
> +				 *  Maintain alignment
> +				 */
> +				lli_len	= (lli_len/mbus->buswidth) *
> +							mbus->buswidth;
> +				odd_bytes = 0;
> +			} else {
> +				/*
> +				 * So now we know how many bytes to transfer
> +				 * to get to the nearest boundary
> +				 * The next lli will past the boundary
> +				 * - however we may be working to a boundary
> +				 *   on the slave bus
> +				 *   We need to ensure the master stays aligned
> +				 */
> +				odd_bytes = lli_len % mbus->buswidth;
> +				/*
> +				 * - and that we are working in multiples
> +				 *   of the bus widths
> +				 */
> +				lli_len -= odd_bytes;
> +
> +			}
> +
> +			if (lli_len) {
> +				/*
> +				 * Check against minimum bus alignment:
> +				 * Calculate actual transfer size in relation to bus
> +				 * width an get a maximum remainder of the smallest
> +				 * bus width - 1
> +				 */
> +				/* FIXME: use round_down()? */
> +				tsize = lli_len / min(mbus->buswidth, sbus->buswidth);
> +				lli_len	= tsize * min(mbus->buswidth, sbus->buswidth);
> +
> +				if (target_len != lli_len) {
> +					dev_vdbg(&pl08x->adev->dev,
> +					"%s can't send what we want. Desired %08x, lli of %08x bytes in txd of %08x\n",
> +					__func__, target_len, lli_len, txd->len);
> +				}
> +
> +				cctl = pl08x_cctl_bits(cctl,
> +						       txd->srcbus.buswidth,
> +						       txd->dstbus.buswidth,
> +						       tsize);
> +
> +				dev_vdbg(&pl08x->adev->dev,
> +					"%s fill lli with single lli chunk of size %08x (remainder %08x)\n",
> +					__func__, lli_len, remainder);
> +				num_llis = pl08x_fill_lli_for_desc(pl08x, txd,
> +						num_llis, lli_len, cctl,
> +						&remainder);
> +				total_bytes += lli_len;
> +			}
> +
> +
> +			if (odd_bytes) {
> +				/*
> +				 * Creep past the boundary,
> +				 * maintaining master alignment
> +				 */
> +				int j;
> +				for (j = 0; (j < mbus->buswidth)
> +						&& (remainder); j++) {
> +					cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
> +					dev_vdbg(&pl08x->adev->dev,
> +						"%s align with boundardy, single byte (remain %08x)\n",
> +						__func__, remainder);
> +					num_llis =
> +						pl08x_fill_lli_for_desc(pl08x,
> +							txd, num_llis, 1,
> +							cctl, &remainder);
> +					total_bytes++;
> +				}
> +			}
> +		}
> +
> +		/*
> +		 * Send any odd bytes
> +		 */
> +		if (remainder < 0) {
> +			dev_err(&pl08x->adev->dev, "%s remainder not fitted 0x%08x bytes\n",
> +					__func__, remainder);
> +			return 0;
> +		}
> +
> +		while (remainder) {
> +			cctl = pl08x_cctl_bits(cctl, 1, 1, 1);
> +			dev_vdbg(&pl08x->adev->dev,
> +				"%s align with boundardy, single odd byte (remain %d)\n",
> +				__func__, remainder);
> +			num_llis = pl08x_fill_lli_for_desc(pl08x, txd, num_llis,
> +					1, cctl, &remainder);
> +			total_bytes++;
> +		}
> +	}
> +	if (total_bytes != txd->len) {
> +		dev_err(&pl08x->adev->dev,
> +			"%s size of encoded lli:s don't match total txd, transferred 0x%08x from size 0x%08x\n",
> +			__func__, total_bytes, txd->len);
> +		return 0;
> +	}
> +
> +	if (num_llis >= MAX_NUM_TSFR_LLIS) {
> +		dev_err(&pl08x->adev->dev,
> +			"%s need to increase MAX_NUM_TSFR_LLIS from 0x%08x\n",
> +			__func__, (u32) MAX_NUM_TSFR_LLIS);
> +		return 0;
> +	}
> +	/*
> +	 * Decide whether this is a loop or a terminated transfer
> +	 */
> +	llis_va = ((struct lli *)txd->llis_va);
> +	llis_bus = ((struct lli *)txd->llis_bus);
> +
> +	if (cd->circular_buffer) {
> +		/*
> +		 * Loop the circular buffer so that the next element
> +		 * points back to the beginning of the LLI.
> +		 */
> +		llis_va[num_llis - 1].next =
> +			(dma_addr_t)((unsigned int)&(llis_bus[0]) +
> +						pl08x->pd->bus_bit_lli);
> +	} else {
> +		/*
> +		 * On non-circular buffers, the final LLI terminates
> +		 * the LLI.
> +		 */
> +		llis_va[num_llis - 1].next = 0;
> +		/*
> +		 * The final LLI element shall also fire an interrupt
> +		 */
> +		llis_va[num_llis - 1].cctl |= PL080_CONTROL_TC_IRQ_EN;
> +	}
> +
> +	/* Now store the channel register values */
> +	txd->csrc = llis_va[0].src;
> +	txd->cdst = llis_va[0].dst;
> +	if (num_llis > 1)
> +		txd->clli = llis_va[0].next;
> +	else
> +		txd->clli = 0;
> +
> +	txd->cctl = llis_va[0].cctl;
> +	/* ccfg will be set at physical channel allocation time */
> +
> +	{
> +		int i;
> +
> +		for (i = 0; i < num_llis; i++) {
> +				dev_vdbg(&pl08x->adev->dev,
> +					"lli %d @%p: csrc=%08x, cdst=%08x, cctl=%08x, clli=%08x\n",
> +					i,
> +					&llis_va[i],
> +					llis_va[i].src,
> +					llis_va[i].dst,
> +					llis_va[i].cctl,
> +					llis_va[i].next
> +					);
> +		}
> +	}
> +
> +	/*
> +	 * Reflects the longest lli submitted so far
> +	 * TODO: Change to use /proc data
> +	 */
> +	if (pl08x->max_num_llis < num_llis)
> +		pl08x->max_num_llis = num_llis;
> +
> +	return num_llis;
> +}
> +
> +/* You should call this with the struct pl08x lock held */
> +static void pl08x_free_txd(struct pl08x_driver_data *pl08x, struct pl08x_txd *txd)
> +{
> +	if (!txd)
> +		dev_err(&pl08x->adev->dev,
> +			"%s no descriptor to free\n",
> +			__func__);
> +
> +	/* Free the LLI */
> +	dma_pool_free(pl08x->pool, txd->llis_va,
> +		      txd->llis_bus);
> +
> +	pl08x->pool_ctr--;
> +
> +	kfree(txd);
> +}
> +
> +static void pl08x_free_txd_list(struct pl08x_driver_data *pl08x, struct list_head *txdlist)
> +{
> +	struct pl08x_txd *txdi = NULL;
> +	struct pl08x_txd *next;
> +
> +	if (!list_empty(txdlist)) {
> +		list_for_each_entry_safe(txdi,
> +					 next, txdlist, node) {
> +			list_del(&txdi->node);
> +			pl08x_free_txd(pl08x, txdi);
> +		}
> +
> +	}
> +}
> +
> +static void pl08x_tasklet(unsigned long data)
> +{
> +	struct pl08x_dma_chan *plchan = (struct pl08x_dma_chan *) data;
> +	struct pl08x_phy_chan *phychan = plchan->phychan;
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	struct pl08x_txd *txdi = NULL;
> +	struct pl08x_txd *next;
> +	unsigned long flags;
> +
> +	if (!plchan)
> +		BUG();
> +
> +	spin_lock_irqsave(&plchan->lock, flags);
> +
> +	if (plchan->at) {
> +		dma_async_tx_callback callback =
> +			plchan->at->tx.callback;
> +		void *callback_param =
> +			plchan->at->tx.callback_param;
> +
> +		/*
> +		 * Update last completed
> +		 */
> +		plchan->lc =
> +			(plchan->at->tx.cookie);
> +
> +		/*
> +		 * Callback peripheral driver for p/m
> +		 * to signal completion
> +		 */
> +		if (callback)
> +			callback(callback_param);
> +
> +		/*
> +		 * Device callbacks should NOT clear
> +		 * the current transaction on the channel
> +		 * Linus: sometimes they should?
> +		 */
> +		if (!plchan->at)
> +			BUG();
> +
> +		/*
> +		 * Free the descriptor if it's not for a device
> +		 * using a circular buffer
> +		 */
> +		if (!plchan->at->cd->circular_buffer) {
> +			pl08x_free_txd(pl08x, plchan->at);
> +			plchan->at = NULL;
> +		}
> +		/*
> +		 * else descriptor for circular
> +		 * buffers only freed when
> +		 * client has disabled dma
> +		 */
> +	}
> +	/*
> +	 * If a new descriptor is queued, set it up
> +	 */
> +	if (!list_empty(&plchan->desc_list)) {
> +		list_for_each_entry_safe(txdi,
> +					 next, &plchan->desc_list, node) {
> +			list_del_init(&txdi->node);
> +		}
> +	} else {
> +		/*
> +		 * No more jobs, so free up the physical channel
> +		 * Free any allocated signal on slave transfers too
> +		 */
> +		if ((phychan->signal >= 0) && pl08x->pd->put_signal)
> +			pl08x->pd->put_signal(plchan);
> +		pl08x_put_phy_channel(pl08x, phychan);
> +		plchan->phychan = NULL;
> +	}
> +
> +	spin_unlock_irqrestore(&plchan->lock, flags);
> +}
> +
> +static irqreturn_t pl08x_irq(int irq, void *dev)
> +{
> +	struct pl08x_driver_data *pl08x = dev;
> +	u32 mask = 0;
> +	u32 val;
> +	int i;
> +
> +	val = readl(pl08x->base + PL080_ERR_STATUS);
> +	mb();
> +	if (val) {
> +		/*
> +		 * An error interrupt (on one or more channels)
> +		 */
> +		dev_err(&pl08x->adev->dev,
> +			"%s error interrupt, register value 0x%08x\n",
> +				__func__, val);
> +		/*
> +		 * Simply clear ALL PL08X error interrupts,
> +		 * regardless of channel and cause
> +		 * FIXME: should be 0x00000003 on PL081 really.
> +		 */
> +		writel(0x000000FF, pl08x->base + PL080_ERR_CLEAR);
> +	}
> +	val = readl(pl08x->base + PL080_INT_STATUS);
> +	mb();
> +	for (i = 0; i < pl08x->vd->channels; i++) {
> +		if ((1 << i) & val) {
> +			/* Locate physical channel */
> +			struct pl08x_phy_chan *phychan = &pl08x->phy_chans[i];
> +			struct pl08x_dma_chan *plchan = phychan->serving;
> +
> +			/* Schedule tasklet on this channel */
> +			tasklet_schedule(&plchan->tasklet);
> +
> +			mask |= (1 << i);
> +		}
> +	}
> +	/*
> +	 * Clear only the terminal interrupts on channels we processed
> +	 */
> +	writel(mask, pl08x->base + PL080_TC_CLEAR);
> +	mb();
> +
> +	return mask ? IRQ_HANDLED : IRQ_NONE;
> +}
> +
> +
> +/*
> + * The DMA ENGINE API
> + */
> +static int pl08x_alloc_chan_resources(struct dma_chan *chan)
> +{
> +	return 0;
> +}
> +
> +static void pl08x_free_chan_resources(struct dma_chan *chan)
> +{
> +}
> +
> +/*
> + * This should be called with the channel plchan->lock held
> + */
> +static int prep_phy_channel(struct pl08x_dma_chan *plchan,
> +			    struct pl08x_txd *txd)
> +{
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	struct pl08x_phy_chan *ch;
> +	int ret;
> +
> +	/* Check if we already have a channel */
> +	if (plchan->phychan)
> +		return 0;
> +
> +	ch = pl08x_get_phy_channel(pl08x, plchan);
> +	if (!ch) {
> +		/* No physical channel available, cope with it */
> +		dev_info(&pl08x->adev->dev, "no physical channel "
> +			"available for xfer on %s\n", plchan->name);
> +		return -EBUSY;
> +	}
> +
> +	/*
> +	 * OK we have a physical channel: for memcpy() this is all we
> +	 * need, but for slaves the physical siglals may be muxed!
> +	 * Can the platform allow us to use this channel?
> +	 */
> +	if ((txd->direction == DMA_FROM_DEVICE || txd->direction == DMA_TO_DEVICE) &&
> +	    pl08x->pd->get_signal) {
> +		ret = pl08x->pd->get_signal(plchan);
> +		if (ret < 0) {
> +			dev_info(&pl08x->adev->dev,
> +				"unable to use physical channel "
> +				"%d for transfer on %s due to "
> +				"platform restrictions\n",
> +				ch->id, plchan->name);
> +			/* Release physical channel & return */
> +			pl08x_put_phy_channel(pl08x, ch);
> +			return -EBUSY;
> +		}
> +		ch->signal = ret;
> +	}
> +
> +	dev_dbg(&pl08x->adev->dev, "allocated physical "
> +		 "channel %d and signal %d for xfer on %s\n",
> +		 ch->id,
> +		 ch->signal,
> +		 plchan->name);
> +
> +	plchan->phychan = ch;
> +
> +	return 0;
> +}
> +
> +/*
> + * First make the LLIs (could/should we do this earlier??)
> + * slave (m/p) - no queued transactions allowed at present
> + *	TODO allow queued transactions for non circular buffers
> + * Set up the channel active txd as inactive
> + * m2m	- transactions may be queued
> + * If no active txd on channel
> + *	set it up as inactive
> + *	- issue_pending() will set active & start
> + * else
> + *	queue it
> + * Lock channel since there may be (at least for m2m) multiple calls
> + *
> + * Return < 0 for error
> + */
> +
> +static dma_cookie_t pl08x_tx_submit(struct dma_async_tx_descriptor *tx)
> +{
> +	int num_llis;
> +	unsigned long flags;
> +	struct pl08x_txd *txd = container_of(tx, struct pl08x_txd, tx);
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(tx->chan);
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	int ret;
> +
> +	num_llis = pl08x_fill_llis_for_desc(pl08x, txd);
> +
> +	if (num_llis) {
> +		spin_lock_irqsave(&plchan->lock, flags);
> +		atomic_inc(&plchan->last_issued);
> +		tx->cookie = atomic_read(&plchan->last_issued);
> +
> +		if (plchan->at) {
> +
> +			/*
> +			 * If this device not using a circular buffer then
> +			 * queue this new descriptor for transfer.
> +			 * The descriptor for a circular buffer continues
> +			 * to be used until the channel is freed.
> +			 */
> +			if (txd->cd->circular_buffer)
> +				dev_err(&pl08x->adev->dev,
> +					"%s attempting to queue a circular buffer\n",
> +						__func__);
> +			else
> +				list_add_tail(&txd->node,
> +					&plchan->desc_list);
> +
> +		} else {
> +			plchan->at = txd;
> +			txd->active = false;
> +		}
> +
> +		/*
> +		 * See if we already have a physical channel allocated,
> +		 * else this is the time to try to get one.
> +		 */
> +		ret = prep_phy_channel(plchan, txd);
> +		if (ret) {
> +			/* No physical channel available, cope with it */
> +			spin_unlock_irqrestore(&plchan->lock, flags);
> +			return -EBUSY;
> +		}
> +
> +		spin_unlock_irqrestore(&plchan->lock, flags);
> +
> +		return tx->cookie;
> +	} else
> +		return -EINVAL;
> +}
> +
> +static struct dma_async_tx_descriptor *pl08x_prep_dma_interrupt(
> +		struct dma_chan *chan, unsigned long flags)
> +{
> +	struct dma_async_tx_descriptor *retval = NULL;
> +
> +	return retval;
> +}
> +
> +/*
> + * Code accessing dma_async_is_complete() in a tight loop
> + * may give problems - could schedule where indicated.
> + * If slaves are relying on interrupts to signal completion this
> + * function must not be called with interrupts disabled
> + */
> +static enum dma_status
> +pl08x_dma_tx_status(struct dma_chan *chan,
> +		    dma_cookie_t cookie,
> +		    struct dma_tx_state *txstate)
> +{
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
> +	dma_cookie_t last_used;
> +	dma_cookie_t last_complete;
> +	enum dma_status ret;
> +	u32 bytesleft = 0;
> +
> +	last_used = atomic_read(&plchan->last_issued);
> +	last_complete = plchan->lc;
> +
> +	ret = dma_async_is_complete(cookie, last_complete, last_used);
> +	if (ret == DMA_SUCCESS) {
> +		dma_set_tx_state(txstate, last_complete, last_used, 0);
> +		return ret;
> +	}
> +
> +	/*
> +	 * schedule(); could be inserted here
> +	 */
> +
> +	/*
> +	 * This cookie not complete yet
> +	 */
> +	last_used = atomic_read(&plchan->last_issued);
> +	last_complete = plchan->lc;
> +
> +	/* Get number of bytes left in the active transaction */
> +	if (plchan->phychan)
> +		bytesleft = pl08x_getbytes_phy_chan(plchan->phychan);
> +
> +	dma_set_tx_state(txstate, last_complete, last_used,
> +			 bytesleft);
> +
> +	return DMA_IN_PROGRESS;
> +	/* FIXME: make possible to return DMA_IN_PROGRESS */
> +}
> +
> +/* PrimeCell DMA extension */
> +struct burst_table {
> +	int burstwords;
> +	u32 reg;
> +};
> +
> +static const struct burst_table burst_sizes[] = {
> +	{
> +		.burstwords = 256,
> +		.reg = (PL080_BSIZE_256 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_256 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +	{
> +		.burstwords = 128,
> +		.reg = (PL080_BSIZE_128 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_128 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +	{
> +		.burstwords = 64,
> +		.reg = (PL080_BSIZE_64 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_64 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +	{
> +		.burstwords = 32,
> +		.reg = (PL080_BSIZE_32 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_32 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +	{
> +		.burstwords = 16,
> +		.reg = (PL080_BSIZE_16 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_16 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +	{
> +		.burstwords = 8,
> +		.reg = (PL080_BSIZE_8 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_8 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +	{
> +		.burstwords = 4,
> +		.reg = (PL080_BSIZE_4 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_4 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +	{
> +		.burstwords = 1,
> +		.reg = (PL080_BSIZE_1 << PL080_CONTROL_SB_SIZE_SHIFT) |
> +			(PL080_BSIZE_1 << PL080_CONTROL_DB_SIZE_SHIFT),
> +	},
> +};
> +
> +static void dma_set_ambaconfig(struct dma_chan *chan,
> +			       struct amba_dma_channel_config *config)
> +{
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	struct pl08x_channel_data *cd = plchan->cd;
> +	int maxburst = config->maxburst;
> +	u32 cctl = 0;
> +	/* Mask out all except src and dst channel */
> +	u32 ccfg = cd->ccfg & 0x000003DEU;
> +	int i = 0;
> +
> +	plchan->amba_addr = config->addr;
> +	plchan->amba_direction = config->direction;
> +
> +	switch (config->addr_width) {
> +	case 1:
> +		cctl |= (PL080_WIDTH_8BIT << PL080_CONTROL_SWIDTH_SHIFT) |
> +			(PL080_WIDTH_8BIT << PL080_CONTROL_DWIDTH_SHIFT);
> +		break;
> +	case 2:
> +		cctl |= (PL080_WIDTH_16BIT << PL080_CONTROL_SWIDTH_SHIFT) |
> +			(PL080_WIDTH_16BIT << PL080_CONTROL_DWIDTH_SHIFT);
> +		break;
> +	case 4:
> +		cctl |= (PL080_WIDTH_32BIT << PL080_CONTROL_SWIDTH_SHIFT) |
> +			(PL080_WIDTH_32BIT << PL080_CONTROL_DWIDTH_SHIFT);
> +		break;
> +	default:
> +		dev_err(&pl08x->adev->dev,
> +			"bad ambaconfig: alien address width\n");
> +		return;
> +	}
> +
> +	/* Now decide on a maxburst */
> +	while (i < ARRAY_SIZE(burst_sizes)) {
> +		if (burst_sizes[i].burstwords <= maxburst)
> +			break;
> +		i++;
> +	}
> +	cctl |= burst_sizes[i].reg;
> +
> +	/* Transfer direction */
> +	if (config->direction == DMA_TO_DEVICE) {
> +		cctl |= PL080_CONTROL_SRC_INCR;
> +		ccfg |= PL080_FLOW_MEM2PER << PL080_CONFIG_FLOW_CONTROL_SHIFT;
> +	} else if (config->direction == DMA_FROM_DEVICE) {
> +		cctl |= PL080_CONTROL_DST_INCR;
> +		ccfg |= PL080_FLOW_PER2MEM << PL080_CONFIG_FLOW_CONTROL_SHIFT;
> +	} else {
> +		dev_err(&pl08x->adev->dev,
> +			"bad ambaconfig: alien transfer direction\n");
> +	}
> +
> +	/* Access the cell in privileged mode, non-bufferable, non-cacheable */
> +	cctl &= ~PL080_CONTROL_PROT_MASK;
> +	cctl |= PL080_CONTROL_PROT_SYS;
> +
> +	/* Modify the default channel data to fit PrimeCell request */
> +	cd->cctl = cctl;
> +	cd->ccfg = ccfg;
> +
> +	dev_info(&pl08x->adev->dev,
> +		 "configured channel %s (%s) for %s, data width %d, "
> +		 "maxburst %d words, LE, CCTL=%08x, CCFG=%08x\n",
> +		 dma_chan_name(chan), plchan->name,
> +		 (config->direction == DMA_FROM_DEVICE) ? "RX" : "TX",
> +		 config->addr_width,
> +		 config->maxburst,
> +		 cctl, ccfg);
> +}
> +
> +/*
> + * Slave transactions callback to the slave device to allow
> + * synchronization of slave DMA signals with the DMAC enable
> + */
> +static void pl08x_issue_pending(struct dma_chan *chan)
> +{
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&plchan->lock, flags);
> +	if (plchan->at) {
> +		if (!plchan->at->active) {
> +			/* Configure the physical channel for the active txd */
> +			pl08x_config_phychan_for_txd(plchan);
> +			pl08x_set_cregs(pl08x, plchan->phychan);
> +			pl08x_enable_phy_chan(pl08x, plchan->phychan);
> +			plchan->at->active = true;
> +		}
> +		/*
> +		 * else skip active transfer
> +		 * Calls with active txd occur for NET_DMA
> +		 * - there can be queued descriptors
> +		 */
> +	}
> +	spin_unlock_irqrestore(&plchan->lock, flags);
> +	/*
> +	 * else - calls with no active descriptor occur for NET_DMA
> +	 */
> +}
> +
> +/*
> + * Initialize a descriptor to be used by memcpy submit
> + */
> +static struct dma_async_tx_descriptor *pl08x_prep_dma_memcpy(
> +		struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> +		size_t len, unsigned long flags)
> +{
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	struct pl08x_txd *txd;
> +
> +	txd = kzalloc(sizeof(struct pl08x_txd), GFP_KERNEL);
> +	if (!txd) {
> +		dev_err(&pl08x->adev->dev,
> +			"%s no memory for descriptor\n", __func__);
> +		return NULL;
> +	}
> +
> +	dma_async_tx_descriptor_init(&txd->tx, chan);
> +	txd->direction = DMA_NONE;
> +	txd->srcbus.addr = src;
> +	txd->dstbus.addr = dest;
> +
> +	/* Set platform data for m2m */
> +	txd->cd = &pl08x->pd->memcpy_channel;
> +	/* Both to be incremented or the code will break */
> +	txd->cd->cctl |= PL080_CONTROL_SRC_INCR | PL080_CONTROL_DST_INCR;
> +	txd->tx.tx_submit = pl08x_tx_submit;
> +	txd->tx.callback = NULL;
> +	txd->tx.callback_param = NULL;
> +	txd->len = len;
> +
> +	INIT_LIST_HEAD(&txd->node);
> +
> +	return &txd->tx;
> +}
> +
> +struct dma_async_tx_descriptor *pl08x_prep_slave_sg(
> +		struct dma_chan *chan, struct scatterlist *sgl,
> +		unsigned int sg_len, enum dma_data_direction direction,
> +		unsigned long flags)
> +{
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	struct pl08x_txd *txd;
> +
> +	/*
> +	 * Current implementation ASSUMES only one sg
> +	 */
> +	if (sg_len != 1) {
> +		dev_err(&pl08x->adev->dev, "%s prepared too long sglist\n",
> +			__func__);
> +		BUG();
> +	}
> +
> +	dev_info(&pl08x->adev->dev, "%s prepare transaction from %s\n",
> +		 __func__, plchan->name);
> +
> +	txd = kmalloc(sizeof(struct pl08x_txd), GFP_KERNEL);
> +	if (!txd) {
> +		dev_err(&pl08x->adev->dev, "%s no txd\n", __func__);
> +		return NULL;
> +	}
> +
> +	dma_async_tx_descriptor_init(&txd->tx, chan);
> +
> +	if (direction != plchan->amba_direction)
> +		dev_err(&pl08x->adev->dev, "%s DMA setup does not match "
> +			"the direction configured for the PrimeCell\n",
> +			__func__);
> +
> +	txd->direction = direction;
> +	if (direction == DMA_TO_DEVICE) {
> +		txd->srcbus.addr	= sgl->dma_address;
> +		txd->dstbus.addr	= plchan->amba_addr;
> +	} else if (direction == DMA_FROM_DEVICE) {
> +		txd->srcbus.addr	= plchan->amba_addr;
> +		txd->dstbus.addr	= sgl->dma_address;
> +	} else {
> +		dev_err(&pl08x->adev->dev,
> +			"%s direction unsupported\n", __func__);
> +		return NULL;
> +	}
> +	txd->cd = plchan->cd;
> +	txd->tx.tx_submit = pl08x_tx_submit;
> +	txd->tx.callback = NULL;
> +	txd->tx.callback_param = NULL;
> +	txd->len = sgl->length;
> +
> +	INIT_LIST_HEAD(&txd->node);
> +
> +	return &txd->tx;
> +}
> +
> +static int pl08x_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> +			 unsigned long arg)
> +{
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
> +	struct pl08x_driver_data *pl08x = plchan->host;
> +	unsigned long flags;
> +
> +	/* Controls applicable to inactive channels */
> +	if (cmd == DMA_CONFIG_AMBA) {
> +		dma_set_ambaconfig(chan,
> +				   (struct amba_dma_channel_config *)
> +				   arg);
> +		return 0;
> +	}
> +
> +	/* Anything succeeds on non-existing transfers */
> +	spin_lock_irqsave(&plchan->lock, flags);
> +	if (!plchan->at || !plchan->phychan) {
> +		spin_unlock_irqrestore(&plchan->lock, flags);
> +		return 0;
> +	}
> +
> +	switch (cmd) {
> +	case DMA_TERMINATE_ALL:
> +		pl08x_stop_phy_chan(plchan->phychan);
> +
> +		/* Mark physical channel as free and free any slave signal */
> +		if ((plchan->phychan->signal >= 0) && pl08x->pd->put_signal)
> +			pl08x->pd->put_signal(plchan);
> +		pl08x_put_phy_channel(pl08x, plchan->phychan);
> +		plchan->phychan = NULL;
> +
> +		/* Dequeue jobs and free LLIs */
> +		pl08x_free_txd(pl08x, plchan->at);
> +		pl08x_free_txd_list(pl08x, &plchan->desc_list);
> +
> +		spin_unlock_irqrestore(&plchan->lock, flags);
> +
> +		return 0;
> +	case DMA_PAUSE:
> +		pl08x_pause_phy_chan(plchan->phychan);
> +		spin_unlock_irqrestore(&plchan->lock, flags);
> +		return 0;
> +	case DMA_RESUME:
> +		pl08x_resume_phy_chan(plchan->phychan);
> +		spin_unlock_irqrestore(&plchan->lock, flags);
> +		return 0;
> +	default:
> +		break;
> +	}
> +	spin_unlock_irqrestore(&plchan->lock, flags);
> +
> +	/* Unknown command */
> +	return -ENXIO;
> +}
> +
> +bool pl08x_filter_id(struct dma_chan *chan, void *chan_id)
> +{
> +	struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
> +	char *name = chan_id;
> +
> +	/* Check that the channel is not taken! */
> +	if (!strcmp(plchan->name, name))
> +		return true;
> +
> +	return false;
> +}
> +
> +struct dma_device dmac_memcpy = {
> +	.device_alloc_chan_resources	= pl08x_alloc_chan_resources,
> +	.device_free_chan_resources	= pl08x_free_chan_resources,
> +	.device_prep_dma_memcpy		= pl08x_prep_dma_memcpy,
> +	.device_prep_dma_xor		= NULL,
> +	.device_prep_dma_memset		= NULL,
> +	.device_prep_dma_interrupt	= pl08x_prep_dma_interrupt,
> +	.device_tx_status		= pl08x_dma_tx_status,
> +	.device_issue_pending		= pl08x_issue_pending,
> +	.device_control			= pl08x_control,
> +	/*
> +	 * Align to 4-byte boundary
> +	 * This makes the DMAtests fail with grace on PB1176
> +	 * broken DMA hardware instead of locking everything
> +	 * up.
> +	 */
> +	/* .copy_align			= 2, */
> +};
> +
> +struct dma_device dmac_slave = {

they must be marked static.

> +	.device_alloc_chan_resources	= pl08x_alloc_chan_resources,
> +	.device_free_chan_resources	= pl08x_free_chan_resources,
> +	.device_prep_dma_xor		= NULL,
> +	.device_prep_dma_memset		= NULL,
> +	.device_prep_dma_interrupt	= pl08x_prep_dma_interrupt,
> +	.device_tx_status		= pl08x_dma_tx_status,
> +	.device_issue_pending		= pl08x_issue_pending,
> +	.device_prep_slave_sg		= pl08x_prep_slave_sg,
> +	.device_control			= pl08x_control,
> +};
> +

One more thing linus, why do we need to create this separation between
channels. i.e. few are for memcpy and few for slave_sg. Why don't all
channels support everything and this is resolved at runtime.

> +
> +/*
> + * Just check that the device is there and active
> + * TODO: turn this bit on/off depending on the number of
> + * physical channels actually used, if it is zero... well
> + * shut it off.
> + */
> +static void pl08x_ensure_on(struct pl08x_driver_data *pl08x)
> +{
> +	u32 val;
> +
> +	val = readl(pl08x->base + PL080_CONFIG);
> +	val &= ~(PL080_CONFIG_M2_BE | PL080_CONFIG_M1_BE | PL080_CONFIG_ENABLE);
> +	/* We implictly clear bit 1 and that means little-endian mode */
> +	val |= PL080_CONFIG_ENABLE;
> +	mb();
> +	writel(val, pl08x->base + PL080_CONFIG);
> +	mb();
> +}
> +
> +/*
> + * Initialise the DMAC memcpy channels.
> + * Make a local wrapper to hold required data
> + */
> +static int pl08x_dma_init_memcpy_channels(struct pl08x_driver_data *pl08x,
> +						 struct dma_device *memdev)
> +{
> +	struct pl08x_dma_chan *chan;
> +	int i;
> +
> +	INIT_LIST_HEAD(&memdev->channels);
> +	/*
> +	 * Register as many many memcpy as we have physical channels,
> +	 * we won't always be able to use all but the code will have
> +	 * to cope with that situation.
> +	 */
> +	for (i = 0; i < pl08x->vd->channels; i++) {
> +		chan = kzalloc(sizeof(struct pl08x_dma_chan), GFP_KERNEL);
> +		if (!chan) {
> +			dev_err(&pl08x->adev->dev,
> +				"%s no memory for channel\n", __func__);
> +			return -ENOMEM;
> +		}
> +
> +		chan->host = pl08x;
> +		chan->name = kasprintf(GFP_KERNEL, "memcpy%d", i);
> +		if (!chan->name) {
> +			kfree(chan);
> +			return -ENOMEM;
> +		}
> +		chan->cd = &pl08x->pd->memcpy_channel;
> +		dev_info(&pl08x->adev->dev,
> +			"initialize virtual memcpy channel \"%s\"\n",
> +			chan->name);
> +
> +		chan->chan.device = memdev;
> +		atomic_set(&chan->last_issued, 0);
> +		chan->lc = atomic_read(&chan->last_issued);
> +
> +		spin_lock_init(&chan->lock);
> +		INIT_LIST_HEAD(&chan->desc_list);
> +		tasklet_init(&chan->tasklet, pl08x_tasklet,
> +			     (unsigned long) chan);
> +
> +		list_add_tail(&chan->chan.device_node, &memdev->channels);
> +	}
> +	dev_info(&pl08x->adev->dev, "initialized %d virtual memcpy channels\n", i);
> +	return i;
> +}
> +
> +/*
> + * Initialise the DMAC slave channels.
> + * Make a local wrapper to hold required data
> + */
> +static int pl08x_dma_init_slave_channels(struct pl08x_driver_data *pl08x,
> +						struct dma_device *slave)

above 2 functions are almost exactly same, can we have single function
instead of two.

> +{
> +	struct pl08x_dma_chan *chan;
> +	int i;
> +
> +	INIT_LIST_HEAD(&slave->channels);
> +	for (i = 0; i < pl08x->pd->num_slave_channels; i++) {
> +		chan = kzalloc(sizeof(struct pl08x_dma_chan), GFP_KERNEL);
> +		if (!chan) {
> +			dev_err(&pl08x->adev->dev,
> +				"%s no memory for channel\n", __func__);
> +			return -ENOMEM;
> +		}
> +
> +		chan->host = pl08x;
> +		chan->name = pl08x->pd->slave_channels[i].bus_id;
> +		chan->cd = &pl08x->pd->slave_channels[i];
> +		dev_info(&pl08x->adev->dev,
> +			"initialize virtual channel \"%s\"\n",
> +			chan->name);
> +
> +		chan->chan.device = slave;
> +		atomic_set(&chan->last_issued, 0);
> +		chan->lc = atomic_read(&chan->last_issued);
> +
> +		spin_lock_init(&chan->lock);
> +		INIT_LIST_HEAD(&chan->desc_list);
> +		tasklet_init(&chan->tasklet, pl08x_tasklet,
> +			     (unsigned long) chan);
> +
> +		list_add_tail(&chan->chan.device_node, &slave->channels);
> +	}
> +	dev_info(&pl08x->adev->dev, "initialized %d virtual slave channels\n", i);
> +	return i;
> +}
> +
> +static int pl08x_probe(struct amba_device *adev, struct amba_id *id)
> +{
> +	struct pl08x_driver_data *pl08x;
> +	struct vendor_data *vd = id->data;
> +	int ret = 0;
> +	int i;
> +
> +	ret = amba_request_regions(adev, NULL);
> +	if (ret)
> +		return ret;
> +
> +	/* Create the driver state holder */
> +	pl08x = kzalloc(sizeof(struct pl08x_driver_data), GFP_KERNEL);
> +	if (!pl08x) {
> +		ret = -ENOMEM;
> +		goto out_no_pl08x;
> +	}
> +
> +	/* Assign useful pointers to the driver state */
> +	pl08x->adev = adev;
> +	pl08x->vd = vd;
> +
> +	/* A DMA memory pool for LLIs, align on 1-byte boundary */
> +	pl08x->pool = dma_pool_create(DRIVER_NAME, &pl08x->adev->dev,
> +			PL08X_LLI_TSFR_SIZE, PL08X_ALIGN, 0);
> +	if (!pl08x->pool) {
> +		ret = -ENOMEM;
> +		goto out_no_lli_pool;
> +	}
> +	pl08x->pool_ctr = 0;
> +	pl08x->max_num_llis = 0;

they are already 0.

> +
> +	spin_lock_init(&pl08x->lock);
> +
> +	pl08x->base = ioremap(adev->res.start, resource_size(&adev->res));
> +	if (!pl08x->base) {
> +		ret = -ENOMEM;
> +		goto out_no_ioremap;
> +	}
> +
> +	/* Turn on the PL08x */
> +	pl08x_ensure_on(pl08x);
> +
> +	/*
> +	 * Attach the interrupt handler
> +	 */
> +	writel(0x000000FF, pl08x->base + PL080_ERR_CLEAR);
> +	writel(0x000000FF, pl08x->base + PL080_TC_CLEAR);
> +	mb();
> +
> +	ret = request_irq(adev->irq[0], pl08x_irq, IRQF_DISABLED,
> +			  vd->name, pl08x);
> +	if (ret) {
> +		dev_err(&adev->dev, "%s failed to request "
> +			"interrupt %d\n",
> +			__func__, adev->irq[0]);

can be written in 2 lines only.

> +		goto out_no_irq;
> +	}
> +
> +	/* Initialize physical channels */
> +	pl08x->phy_chans = kmalloc((vd->channels * sizeof(struct pl08x_phy_chan)),
> +			GFP_KERNEL);
> +	if (!pl08x->phy_chans) {
> +		dev_err(&adev->dev, "%s failed to allocate "
> +			"physical channel holders\n",
> +			__func__);
> +		goto out_no_phychans;
> +	}
> +
> +	for (i = 0; i < vd->channels; i++) {
> +		struct pl08x_phy_chan *ch = &pl08x->phy_chans[i];
> +
> +		ch->id = i;
> +		ch->base = pl08x->base + PL080_Cx_BASE(i);
> +		spin_lock_init(&ch->lock);
> +		ch->serving = NULL;
> +		ch->signal = -1;
> +		dev_info(&adev->dev,
> +			 "physical channel %d is %s\n", i,
> +			 pl08x_phy_channel_busy(ch) ? "BUSY" : "FREE");
> +	}
> +
> +	/* Get the platform data */
> +	pl08x->pd = (struct pl08x_platform_data *)(adev->dev.platform_data);

better to use dev_get_platdata, also no need of typecasting as
platform_data is of type void*.

> +
> +	/* Set caps */
> +	dma_cap_set(DMA_MEMCPY, dmac_memcpy.cap_mask);
> +	dma_cap_set(DMA_SLAVE, dmac_slave.cap_mask);
> +	dmac_memcpy.dev = &adev->dev;
> +	dmac_slave.dev = &adev->dev;
> +
> +	/* Register memcpy channels */
> +	ret = pl08x_dma_init_memcpy_channels(pl08x, &dmac_memcpy);
> +	if (ret <= 0) {
> +		dev_warn(&pl08x->adev->dev,
> +			 "%s failed to enumerate memcpy channels - %d\n",
> +			 __func__, ret);
> +		goto out_no_memcpy;
> +	}
> +	dmac_memcpy.chancnt = ret;
> +
> +	/* Register slave channels */
> +	ret = pl08x_dma_init_slave_channels(pl08x, &dmac_slave);
> +	if (ret <= 0) {
> +		dev_warn(&pl08x->adev->dev,
> +			"%s failed to enumerate slave channels - %d\n",
> +				__func__, ret);
> +		goto out_no_slave;
> +	}
> +	dmac_slave.chancnt = ret;
> +
> +	ret = dma_async_device_register(&dmac_memcpy);
> +	if (ret) {
> +		dev_warn(&pl08x->adev->dev,
> +			"%s failed to register memcpy as an async device - %d\n",
> +			__func__, ret);
> +		goto out_no_memcpy_reg;
> +	}
> +
> +	ret = dma_async_device_register(&dmac_slave);
> +	if (ret) {
> +		dev_warn(&pl08x->adev->dev,
> +			"%s failed to register slave as an async device - %d\n",
> +			__func__, ret);
> +		goto out_no_slave_reg;
> +	}
> +
> +	amba_set_drvdata(adev, pl08x);
> +	dev_info(&pl08x->adev->dev, "ARM(R) %s DMA block initialized @%08x\n",
> +		vd->name, adev->res.start);
> +	return 0;
> +
> +out_no_slave_reg:
> +	dma_async_device_unregister(&dmac_memcpy);
> +out_no_memcpy_reg:
> +	/* FIXME: free slave channels */
> +out_no_slave:
> +	/* FIXME: free memcpy channels */
> +out_no_memcpy:
> +	kfree(pl08x->phy_chans);
> +out_no_phychans:
> +	free_irq(adev->irq[0], pl08x);
> +out_no_irq:
> +	iounmap(pl08x->base);
> +out_no_ioremap:
> +	dma_pool_destroy(pl08x->pool);
> +out_no_lli_pool:
> +	kfree(pl08x);
> +out_no_pl08x:
> +	amba_release_regions(adev);
> +	return ret;
> +}
> +
> +/* PL080 has 8 channels and the PL080 have just 2 */

"PL080 or PL081 have just 2"?? You mentioned at the beginning of this
file, that PL081 has 16 channels. Am i missing something??

> +static struct vendor_data vendor_pl080 = {
> +	.name = "PL080",
> +	.channels = 8,
> +};
> +
> +static struct vendor_data vendor_pl081 = {
> +	.name = "PL081",
> +	.channels = 2,
> +};
> +
> +static struct amba_id pl08x_ids[] = {
> +	/* PL080 */
> +	{
> +		.id	= 0x00041080,
> +		.mask	= 0x000fffff,
> +		.data	= &vendor_pl080,
> +	},
> +	/* PL081 */
> +	{
> +		.id	= 0x00041081,
> +		.mask	= 0x000fffff,
> +		.data	= &vendor_pl081,
> +	},
> +	/* Nomadik 8815 PL080 variant */
> +	{
> +		.id	= 0x00280880,
> +		.mask	= 0x00ffffff,
> +		.data	= &vendor_pl080,
> +	},
> +	{ 0, 0 },
> +};
> +
> +static struct amba_driver pl08x_amba_driver = {
> +	.drv.name	= DRIVER_NAME,
> +	.id_table	= pl08x_ids,
> +	.probe		= pl08x_probe,
> +};
> +
> +static int __init pl08x_init(void)
> +{
> +	int retval;
> +	retval = amba_driver_register(&pl08x_amba_driver);
> +	if (retval)
> +		printk(KERN_WARNING
> +			"PL08X::pl08x_init() - failed to register as an amba device - %d\n",
> +			retval);
> +	return retval;
> +}
> +subsys_initcall(pl08x_init);
> diff --git a/include/linux/amba/pl08x.h b/include/linux/amba/pl08x.h
> new file mode 100644
> index 0000000..5f9b16f
> --- /dev/null
> +++ b/include/linux/amba/pl08x.h
> @@ -0,0 +1,173 @@
> +/*
> + *	linux/amba/pl08x.h - ARM PrimeCell DMA Controller driver
> + *
> + *	Copyright (C) 2005 ARM Ltd
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * pl08x information required by platform code
> + *
> + * Please credit ARM.com
> + * Documentation: ARM DDI 0196D
> + *
> + */
> +
> +#ifndef AMBA_PL08X_H
> +#define AMBA_PL08X_H
> +
> +/* We need sizes of structs from this header */
> +#include <linux/dmaengine.h>
> +
> +/**
> + * struct pl08x_channel_data - data structure to pass info between
> + * platform and PL08x driver regarding channel configuration
> + * @bus_id: name of this device channel, not just a device name since
> + * devices may have more than one channel e.g. "foo_tx"
> + * @min_signal: the minimum DMA signal number to be muxed in for this
> + * channel (for platforms supporting muxed signals). If you have
> + * static assignments, make sure this is set to the assigned signal
> + * number, PL08x have 16 possible signals in number 0 thru 15 so
> + * when these are not enough they often get muxed (in hardware)
> + * disabling simultaneous use of the same channel for two devices.
> + * @max_signal: the maximum DMA signal number to be muxed in for
> + * the channel. Set to the same as min_signal for
> + * devices with static assignments
> + * @muxval: a number usually used to poke into some mux regiser to
> + * mux in the signal to this channel
> + * @cctl_opt: default options for the channel control register
> + * @circular_buffer: whether the buffer passed in is circular and
> + * shall simply be looped round round (like a record baby round
> + * round round round)
> + */
> +struct pl08x_channel_data {
> +	char *bus_id;
> +	int min_signal;
> +	int max_signal;
> +	u32 muxval;
> +	unsigned int cctl; /* Turn me into u32? */
> +	u32 ccfg;
> +	bool circular_buffer;
> +};
> +
> +/**
> + * struct pl08x_bus_data - information of source or destination
> + * busses for a transfer
> + * @addr: current address
> + * @maxwidth: the maximum width of a transfer on this bus
> + * @buswidth: the width of this bus in bytes: 1, 2 or 4
> + * @fill_bytes: bytes required to fill to the next bus memory
> + * boundary
> + */
> +struct pl08x_bus_data {
> +	dma_addr_t addr;
> +	u8 maxwidth;
> +	u8 buswidth;
> +	u32 fill_bytes;
> +};
> +
> +/**
> + * struct pl08x_phy_chan - holder for the physical channels
> + * @id: physical index to this channel
> + * @lock: a lock to use when altering an instance of this struct
> + * @signal: the physical signal (aka channel) serving this
> + * physical channel right now
> + * @serving: the virtual channel currently being served by this
> + * physical channel
> + */
> +struct pl08x_phy_chan {
> +	unsigned int id;
> +	void __iomem *base;
> +	spinlock_t lock;
> +	int signal;
> +	struct pl08x_dma_chan *serving;
> +	u32 csrc;
> +	u32 cdst;
> +	u32 clli;
> +	u32 cctl;
> +	u32 ccfg;
> +};
> +
> +/**
> + * struct pl08x_txd - wrapper for struct dma_async_tx_descriptor
> + * @llis_bus: DMA memory address (physical) start for the LLIs
> + * @llis_va: virtual memory address start for the LLIs
> + */
> +struct pl08x_txd {
> +	struct dma_async_tx_descriptor tx;
> +	enum dma_data_direction	direction;
> +	struct pl08x_bus_data srcbus;
> +	struct pl08x_bus_data dstbus;
> +	int len;
> +	dma_addr_t llis_bus;
> +	void *llis_va;
> +	struct list_head node;
> +	struct pl08x_channel_data *cd;
> +	bool active;
> +	/* Settings to be put into the physical channel when we submit this txd */
> +	u32 csrc;
> +	u32 cdst;
> +	u32 clli;
> +	u32 cctl;
> +};
> +
> +/**
> + * struct pl08x_dma_chan - this structure wraps a DMA ENGINE channel
> + * @chan: wrappped abstract channel
> + * @phychan: the physical channel utilized by this channel, if there is one
> + * @tasklet: tasklet scheduled by the IRQ to handle actual work etc
> + * @name: name of channel
> + * @cd: channel platform data
> + * @amba_addr: address for RX/TX according to the PrimeCell config
> + * @amba_direction: current direction of this channel according to
> + * @lc: last completed transaction on this channel
> + * @desc_list: queued transactions pending on this channel
> + * @at: active transaction on this channel
> + * @lock: a lock for this channel data
> + * @host: a pointer to the host (internal use)
> + */
> +struct pl08x_dma_chan {
> +	struct dma_chan chan;
> +	struct pl08x_phy_chan *phychan;
> +	struct tasklet_struct tasklet;
> +	char *name;
> +	struct pl08x_channel_data *cd;
> +	dma_addr_t amba_addr;
> +	enum dma_data_direction	amba_direction;
> +	atomic_t last_issued;
> +	dma_cookie_t lc;
> +	struct list_head desc_list;
> +	struct pl08x_txd *at;
> +	spinlock_t lock;
> +	void *host;
> +};
> +
> +/**
> + * struct pl08x_platform_data - the platform configuration for the
> + * PL08x PrimeCells.
> + * @slave_channels: the channels defined for the different devices on the
> + * platform, all inclusive, including multiplexed channels. The available
> + * physical channels will be multiplexed around these signals as they
> + * are requested, just enumerate all possible channels.
> + * @get_signal: request a physical signal to be used for a DMA
> + * transfer immediately: if there is some multiplexing or similar blocking
> + * the use of the channel the transfer can be denied by returning
> + * less than zero, else it returns the allocated signal number
> + * @put_signal: indicate to the platform that this physical signal is not
> + * running any DMA transfer and multiplexing can be recycled
> + * @bus_bit_lli: Bit[0] of the address indicated which AHB bus master the
> + * LLI addresses are on 0/1 Master 1/2.
> + */
> +struct pl08x_platform_data {
> +	struct pl08x_channel_data *slave_channels;
> +	unsigned int num_slave_channels;
> +	struct pl08x_channel_data memcpy_channel;
> +	int (*get_signal)(struct pl08x_dma_chan *);
> +	void (*put_signal)(struct pl08x_dma_chan *);
> +	unsigned int bus_bit_lli:1;
> +};
> +
> +bool pl08x_filter_id(struct dma_chan *chan, void *chan_id);
> +
> +#endif	/* AMBA_PL08X_H */