Message-ID: <20131108181743.GR2493@sirena.org.uk>
Date:	Fri, 8 Nov 2013 18:17:43 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Florian Meier <florian.meier@...lo.de>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	Vinod Koul <vinod.koul@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	linux-rpi-kernel <linux-rpi-kernel@...ts.infradead.org>,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
	Liam Girdwood <lgirdwood@...il.com>,
	alsa-devel@...a-project.org, Martin Sperl <martin@...rl.org>
Subject: Re: [PATCH] dmaengine: Add support for BCM2835.

On Fri, Nov 08, 2013 at 06:22:34PM +0100, Florian Meier wrote:
> Add support for DMA controller of BCM2835 as used in the Raspberry Pi.
> Currently it only supports cyclic DMA for serving the I2S driver.

Adding in Martin Sperl who's been looking at DMA with regard to the SPI
controller (which will want non-cyclic mode but I guess there's a lot of
shared code).

> 
> Signed-off-by: Florian Meier <florian.meier@...lo.de>
> ---
>  arch/arm/boot/dts/bcm2835.dtsi |   22 +
>  drivers/dma/Kconfig            |    6 +
>  drivers/dma/Makefile           |    1 +
>  drivers/dma/bcm2835-dma.c      |  880 ++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 909 insertions(+)
>  create mode 100644 drivers/dma/bcm2835-dma.c
> 
> diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi
> index 1e12aef..1514198 100644
> --- a/arch/arm/boot/dts/bcm2835.dtsi
> +++ b/arch/arm/boot/dts/bcm2835.dtsi
> @@ -103,6 +103,28 @@
>  			clocks = <&clk_mmc>;
>  			status = "disabled";
>  		};
> +
> +		dma: dma@...07000 {
> +			compatible = "brcm,bcm2835-dma";
> +			reg = <0x7e007000 0xf00>;
> +			interrupts = <1 16
> +				      1 17
> +				      1 18
> +				      1 19
> +				      1 20
> +				      1 21
> +				      1 22
> +				      1 23
> +				      1 24
> +				      1 25
> +				      1 26
> +				      1 27
> +				      1 28>;
> +
> +			#dma-cells = <1>;
> +			dma-channels = <15>;   /* DMA channel 15 is not handled yet */
> +			dma-requests = <32>;
> +		};
>  	};
>  
>  	clocks {
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index f238cfd..f2d253b 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -288,6 +288,12 @@ config DMA_OMAP
>  	select DMA_ENGINE
>  	select DMA_VIRTUAL_CHANNELS
>  
> +config DMA_BCM2835
> +	tristate "BCM2835 DMA engine support"
> +	depends on (ARCH_BCM2835 || MACH_BCM2708)
> +	select DMA_ENGINE
> +	select DMA_VIRTUAL_CHANNELS
> +
>  config TI_CPPI41
>  	tristate "AM33xx CPPI41 DMA support"
>  	depends on ARCH_OMAP
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index db89035..6348157 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_EP93XX_DMA) += ep93xx_dma.o
>  obj-$(CONFIG_DMA_SA11X0) += sa11x0-dma.o
>  obj-$(CONFIG_MMP_TDMA) += mmp_tdma.o
>  obj-$(CONFIG_DMA_OMAP) += omap-dma.o
> +obj-$(CONFIG_DMA_BCM2835) += bcm2835-dma.o
>  obj-$(CONFIG_MMP_PDMA) += mmp_pdma.o
>  obj-$(CONFIG_DMA_JZ4740) += dma-jz4740.o
>  obj-$(CONFIG_TI_CPPI41) += cppi41.o
> diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> new file mode 100644
> index 0000000..c3e53b3
> --- /dev/null
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -0,0 +1,880 @@
> +/*
> + * BCM2835 DMA engine support
> + *
> + * This driver only supports cyclic DMA transfers
> + * as needed for the I2S module.
> + *
> + * Author:      Florian Meier, <florian.meier@...lo.de>
> + *              Copyright 2013
> + *
> + * based on
> + *	OMAP DMAengine support by Russell King
> + *
> + *	BCM2708 DMA Driver
> + *	Copyright (C) 2010 Broadcom
> + *
> + *	Raspberry Pi PCM I2S ALSA Driver
> + *	Copyright (c) by Phil Poole 2013
> + *
> + * 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
> + */
> +#include <linux/dmaengine.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/spinlock.h>
> +#include <linux/irq.h>
> +#include <linux/of.h>
> +#include <linux/of_dma.h>
> +
> +#include "virt-dma.h"
> +
> +struct bcm2835_dmadev {
> +	struct dma_device ddev;
> +	spinlock_t lock;
> +	struct tasklet_struct task;
> +	struct list_head pending;
> +	uint32_t chans_available;
> +	void __iomem *dma_base;
> +	int *dma_irq_numbers;
> +};
> +
> +struct bcm2835_dma_cb {
> +	unsigned long info;
> +	unsigned long src;
> +	unsigned long dst;
> +	unsigned long length;
> +	unsigned long stride;
> +	unsigned long next;
> +	unsigned long pad[2];
> +};
> +
> +struct bcm2835_chan {
> +	struct virt_dma_chan vc;
> +	struct list_head node;
> +
> +	struct dma_slave_config	cfg;
> +	unsigned dma_sig;
> +	bool cyclic;
> +
> +	int dma_ch;
> +	struct bcm2835_desc *desc;
> +	unsigned sgidx;
> +
> +	void __iomem *dma_chan_base;
> +	int dma_irq_number;
> +	struct irqaction dma_irq_handler;
> +};
> +
> +struct bcm2835_sg {
> +	dma_addr_t addr;
> +	uint32_t en;		/* number of elements (24-bit) */
> +	uint32_t fn;		/* number of frames (16-bit) */
> +};
> +
> +struct bcm2835_desc {
> +	struct virt_dma_desc vd;
> +	enum dma_transfer_direction dir;
> +	dma_addr_t dev_addr;
> +
> +	uint8_t es;
> +	unsigned int sync_type;
> +	unsigned int sync_dreq;
> +
> +	unsigned int control_block_size;
> +	struct bcm2835_dma_cb *control_block_base;
> +	dma_addr_t control_block_base_phys;
> +
> +	unsigned sglen;
> +	struct bcm2835_sg sg[0];
> +};
> +
> +#define BCM2835_DMA_CS		0x00
> +#define BCM2835_DMA_ADDR	0x04
> +#define BCM2835_DMA_SOURCE_AD	0x0c
> +#define BCM2835_DMA_DEST_AD	0x10
> +#define BCM2835_DMA_NEXTCB	0x1C
> +
> +/* DMA CS Control and Status bits */
> +#define BCM2835_DMA_ACTIVE	(1 << 0)
> +#define BCM2835_DMA_INT		(1 << 2)
> +#define BCM2835_DMA_ISPAUSED	(1 << 4)  /* Pause requested or not active */
> +#define BCM2835_DMA_ISHELD	(1 << 5)  /* Is held by DREQ flow control */
> +#define BCM2835_DMA_ERR		(1 << 8)
> +#define BCM2835_DMA_ABORT	(1 << 30) /* stop current CB, go to next, WO */
> +#define BCM2835_DMA_RESET	(1 << 31) /* WO, self clearing */
> +
> +#define BCM2835_DMA_INT_EN	(1 << 0)
> +#define BCM2835_DMA_D_INC	(1 << 4)
> +#define BCM2835_DMA_D_DREQ	(1 << 6)
> +#define BCM2835_DMA_S_INC	(1 << 8)
> +#define BCM2835_DMA_S_DREQ	(1 << 6)
> +
> +#define	BCM2835_DMA_PER_MAP(x)	((x) << 16)
> +
> +#define BCM2835_DMA_DATA_TYPE_S8 1
> +#define BCM2835_DMA_DATA_TYPE_S16 2
> +#define BCM2835_DMA_DATA_TYPE_S32 4
> +#define BCM2835_DMA_DATA_TYPE_S128 16
> +
> +#define BCM2835_DMA_CHANNEL_MASK 32565
> +
> +/* valid only for channels 0 - 14, 15 has its own base address */
> +#define BCM2835_DMA_CHAN(n)	((n)<<8) /* base address */
> +#define BCM2835_DMA_CHANIO(dma_base, n) ((dma_base)+BCM2835_DMA_CHAN(n))
> +
> +static const unsigned es_bytes[] = {
> +	[BCM2835_DMA_DATA_TYPE_S8] = 1,
> +	[BCM2835_DMA_DATA_TYPE_S16] = 2,
> +	[BCM2835_DMA_DATA_TYPE_S32] = 4,
> +	[BCM2835_DMA_DATA_TYPE_S128] = 16
> +};
> +
> +static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
> +{
> +	return container_of(d, struct bcm2835_dmadev, ddev);
> +}
> +
> +static inline struct bcm2835_chan *to_bcm2835_dma_chan(struct dma_chan *c)
> +{
> +	return container_of(c, struct bcm2835_chan, vc.chan);
> +}
> +
> +static inline struct bcm2835_desc *to_bcm2835_dma_desc(
> +		struct dma_async_tx_descriptor *t)
> +{
> +	return container_of(t, struct bcm2835_desc, vd.tx);
> +}
> +
> +static bool bcm2835_dma_filter_fn(struct dma_chan *chan, void *param)
> +{
> +	return true;
> +}
> +
> +static struct of_dma_filter_info bcm2835_dma_info = {
> +	.filter_fn = bcm2835_dma_filter_fn,
> +};
> +
> +static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
> +{
> +	struct bcm2835_desc *desc = container_of(vd, struct bcm2835_desc, vd);
> +	dma_free_coherent(desc->vd.tx.chan->device->dev,
> +			desc->control_block_size,
> +			desc->control_block_base,
> +			desc->control_block_base_phys);
> +	kfree(desc);
> +}
> +
> +static void bcm2835_dma_start(void __iomem *dma_chan_base,
> +		dma_addr_t control_block)
> +{
> +	dsb();	/* ARM data synchronization (push) operation */
> +
> +	writel(control_block, dma_chan_base+BCM2835_DMA_ADDR);
> +	writel(BCM2835_DMA_ACTIVE, dma_chan_base+BCM2835_DMA_CS);
> +}
> +
> +static int bcm2835_dma_abort(void __iomem *dma_chan_base)
> +{
> +	unsigned long int cs;
> +	int rc = 0;
> +
> +	cs = readl(dma_chan_base + BCM2835_DMA_CS);
> +
> +	if (BCM2835_DMA_ACTIVE & cs) {
> +		long int timeout = 10000;
> +
> +		/* write 0 to the active bit - pause the DMA */
> +		writel(0, dma_chan_base + BCM2835_DMA_CS);
> +
> +		/* wait for any current AXI transfer to complete */
> +		while (0 != (cs & BCM2835_DMA_ISPAUSED) && --timeout >= 0)
> +			cs = readl(dma_chan_base + BCM2835_DMA_CS);
> +
> +		if (0 != (cs & BCM2835_DMA_ISPAUSED)) {
> +			/* we'll un-pause when we set of our next DMA */
> +			rc = -ETIMEDOUT;
> +
> +		} else if (BCM2835_DMA_ACTIVE & cs) {
> +			/* terminate the control block chain */
> +			writel(0, dma_chan_base + BCM2835_DMA_NEXTCB);
> +
> +			/* abort the whole DMA */
> +			writel(BCM2835_DMA_ABORT | BCM2835_DMA_ACTIVE,
> +			       dma_chan_base + BCM2835_DMA_CS);
> +		}
> +	}
> +
> +	return rc;
> +}
> +
> +static void bcm2835_dma_start_sg(struct bcm2835_chan *c, struct bcm2835_desc *d,
> +		unsigned idx)
> +{
> +	struct bcm2835_sg *sg = d->sg + idx;
> +	int frame;
> +	int frames = sg->fn;
> +
> +	/*
> +	 * Iterate over all frames and create a control block
> +	 * for each frame and link them together.
> +	 */
> +	for (frame = 0; frame < frames; frame++) {
> +		struct bcm2835_dma_cb *control_block =
> +			&d->control_block_base[frame];
> +
> +		/* Setup adresses */
> +		if (d->dir == DMA_DEV_TO_MEM) {
> +			control_block->info = BCM2835_DMA_D_INC;
> +			control_block->src = d->dev_addr;
> +			control_block->dst = sg->addr+frame*sg->en;
> +		} else {
> +			control_block->info = BCM2835_DMA_S_INC;
> +			control_block->src = sg->addr+frame*sg->en;
> +			control_block->dst = d->dev_addr;
> +		}
> +
> +		/* Enable interrupt */
> +		control_block->info |= BCM2835_DMA_INT_EN;
> +
> +		/* Setup synchronization */
> +		if (d->sync_type != 0)
> +			control_block->info |= d->sync_type;
> +
> +		/* Setup DREQ channel */
> +		if (d->sync_dreq != 0)
> +			control_block->info |=
> +				BCM2835_DMA_PER_MAP(d->sync_dreq);
> +
> +		/* Length of a frame */
> +		control_block->length = sg->en;
> +
> +		/*
> +		 * Next block is the next frame.
> +		 * This DMA engine driver currently only supports cyclic DMA.
> +		 * Therefore, wrap around at number of frames.
> +		 */
> +		control_block->next = d->control_block_base_phys +
> +			sizeof(struct bcm2835_dma_cb)*((frame+1)%(frames));
> +
> +		/* The following fields are not used here */
> +		control_block->stride = 0;
> +		control_block->pad[0] = 0;
> +		control_block->pad[1] = 0;
> +	}
> +
> +	/* Start the DMA transfer */
> +	bcm2835_dma_start(c->dma_chan_base, d->control_block_base_phys);
> +}
> +
> +static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
> +{
> +	struct virt_dma_desc *vd = vchan_next_desc(&c->vc);
> +	struct bcm2835_desc *d;
> +
> +	if (!vd) {
> +		c->desc = NULL;
> +		return;
> +	}
> +
> +	list_del(&vd->node);
> +
> +	c->desc = d = to_bcm2835_dma_desc(&vd->tx);
> +	c->sgidx = 0;
> +
> +	bcm2835_dma_start_sg(c, d, 0);
> +}
> +
> +static irqreturn_t bcm2835_dma_callback(int irq, void *data)
> +{
> +	struct bcm2835_chan *c = data;
> +	struct bcm2835_desc *d;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&c->vc.lock, flags);
> +
> +	/* acknowledge interrupt */
> +	writel(BCM2835_DMA_INT, c->dma_chan_base + BCM2835_DMA_CS);
> +
> +	d = c->desc;
> +
> +	if (d) {
> +		if (!c->cyclic) {
> +			if (++c->sgidx < d->sglen) {
> +				bcm2835_dma_start_sg(c, d, c->sgidx);
> +			} else {
> +				bcm2835_dma_start_desc(c);
> +				vchan_cookie_complete(&d->vd);
> +			}
> +		} else {
> +			vchan_cyclic_callback(&d->vd);
> +		}
> +	}
> +
> +	/* keep the DMA engine running */
> +	dsb(); /* ARM synchronization barrier */
> +	writel(BCM2835_DMA_ACTIVE, c->dma_chan_base + BCM2835_DMA_CS);
> +
> +	spin_unlock_irqrestore(&c->vc.lock, flags);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/*
> + * This callback schedules all pending channels.  We could be more
> + * clever here by postponing allocation of the real DMA channels to
> + * this point, and freeing them when our virtual channel becomes idle.
> + *
> + * We would then need to deal with 'all channels in-use'
> + */
> +static void bcm2835_dma_sched(unsigned long data)
> +{
> +	struct bcm2835_dmadev *d = (struct bcm2835_dmadev *)data;
> +	LIST_HEAD(head);
> +
> +	spin_lock_irq(&d->lock);
> +	list_splice_tail_init(&d->pending, &head);
> +	spin_unlock_irq(&d->lock);
> +
> +	while (!list_empty(&head)) {
> +		struct bcm2835_chan *c = list_first_entry(&head,
> +			struct bcm2835_chan, node);
> +
> +		spin_lock_irq(&c->vc.lock);
> +		list_del_init(&c->node);
> +		bcm2835_dma_start_desc(c);
> +		spin_unlock_irq(&c->vc.lock);
> +	}
> +}
> +
> +static int bcm2835_dma_alloc_chan_resources(struct dma_chan *chan)
> +{
> +	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> +	int ret;
> +	struct bcm2835_dmadev *d = to_bcm2835_dma_dev(chan->device);
> +	uint32_t chans = d->chans_available;
> +	int chanID = 0;
> +
> +	dev_dbg(c->vc.chan.device->dev,
> +			"allocating channel for %u\n", c->dma_sig);
> +
> +	/* do not use the FIQ and BULK channels */
> +	chans &= ~0xD;
> +
> +	if (chans) {
> +		/* return the ordinal of the first channel in the bitmap */
> +		while (chans != 0 && (chans & 1) == 0) {
> +			chans >>= 1;
> +			chanID++;
> +		}
> +
> +		/* claim the channel */
> +		d->chans_available &= ~(1 << chanID);
> +
> +		c->dma_chan_base = BCM2835_DMA_CHANIO(d->dma_base, chanID);
> +
> +		c->dma_irq_number = d->dma_irq_numbers[chanID];
> +
> +		c->dma_ch = chanID;
> +	} else {
> +		return -ENOMEM;
> +	}
> +
> +	c->dma_irq_handler.name = "DMA engine IRQ handler";
> +	c->dma_irq_handler.flags = 0;
> +	c->dma_irq_handler.handler = bcm2835_dma_callback;
> +
> +	ret = request_any_context_irq(c->dma_irq_number,
> +			bcm2835_dma_callback, 0, "DMA IRQ", c);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static void bcm2835_dma_free_chan_resources(struct dma_chan *chan)
> +{
> +	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> +	struct bcm2835_dmadev *d = to_bcm2835_dma_dev(chan->device);
> +
> +	vchan_free_chan_resources(&c->vc);
> +	d->chans_available |= (1 << c->dma_ch);
> +	free_irq(c->dma_irq_number, c);
> +
> +	dev_dbg(c->vc.chan.device->dev, "freeing channel for %u\n", c->dma_sig);
> +}
> +
> +static size_t bcm2835_dma_sg_size(struct bcm2835_sg *sg)
> +{
> +	return sg->en * sg->fn;
> +}
> +
> +static size_t bcm2835_dma_desc_size(struct bcm2835_desc *d)
> +{
> +	unsigned i;
> +	size_t size;
> +
> +	for (size = i = 0; i < d->sglen; i++)
> +		size += bcm2835_dma_sg_size(&d->sg[i]);
> +
> +	return size * es_bytes[d->es];
> +}
> +
> +static size_t bcm2835_dma_desc_size_pos(struct bcm2835_desc *d, dma_addr_t addr)
> +{
> +	unsigned i;
> +	size_t size;
> +
> +	for (size = i = 0; i < d->sglen; i++) {
> +		size_t this_size = bcm2835_dma_sg_size(&d->sg[i]);
> +
> +		if (size)
> +			size += this_size;
> +		else if (addr >= d->sg[i].addr &&
> +			 addr < d->sg[i].addr + this_size)
> +			size += d->sg[i].addr + this_size - addr;
> +	}
> +	return size;
> +}
> +
> +
> +/*
> + * Returns current physical source address for the given DMA channel.
> + * If the channel is running the caller must disable interrupts prior calling
> + * this function and process the returned value before re-enabling interrupt to
> + * prevent races with the interrupt handler.
> + */
> +static dma_addr_t bcm2835_get_dma_src_pos(struct bcm2835_chan *c)
> +{
> +	return readl(c->dma_chan_base + BCM2835_DMA_SOURCE_AD);
> +}
> +
> +/*
> + * Returns current physical destination address for the given DMA channel.
> + * If the channel is running the caller must disable interrupts prior calling
> + * this function and process the returned value before re-enabling interrupt to
> + * prevent races with the interrupt handler.
> + */
> +static dma_addr_t bcm2835_get_dma_dst_pos(struct bcm2835_chan *c)
> +{
> +	return readl(c->dma_chan_base + BCM2835_DMA_DEST_AD);
> +}
> +
> +static enum dma_status bcm2835_dma_tx_status(struct dma_chan *chan,
> +	dma_cookie_t cookie, struct dma_tx_state *txstate)
> +{
> +	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> +	struct virt_dma_desc *vd;
> +	enum dma_status ret;
> +	unsigned long flags;
> +
> +	ret = dma_cookie_status(chan, cookie, txstate);
> +	if (ret == DMA_SUCCESS || !txstate)
> +		return ret;
> +
> +	spin_lock_irqsave(&c->vc.lock, flags);
> +	vd = vchan_find_desc(&c->vc, cookie);
> +	if (vd) {
> +		txstate->residue =
> +			bcm2835_dma_desc_size(to_bcm2835_dma_desc(&vd->tx));
> +	} else if (c->desc && c->desc->vd.tx.cookie == cookie) {
> +		struct bcm2835_desc *d = c->desc;
> +		dma_addr_t pos;
> +
> +		if (d->dir == DMA_MEM_TO_DEV)
> +			pos = bcm2835_get_dma_src_pos(c);
> +		else if (d->dir == DMA_DEV_TO_MEM)
> +			pos = bcm2835_get_dma_dst_pos(c);
> +		else
> +			pos = 0;
> +
> +		txstate->residue = bcm2835_dma_desc_size_pos(d, pos);
> +	} else {
> +		txstate->residue = 0;
> +	}
> +
> +	spin_unlock_irqrestore(&c->vc.lock, flags);
> +
> +	return ret;
> +}
> +
> +static void bcm2835_dma_issue_pending(struct dma_chan *chan)
> +{
> +	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&c->vc.lock, flags);
> +	if (vchan_issue_pending(&c->vc) && !c->desc) {
> +		struct bcm2835_dmadev *d = to_bcm2835_dma_dev(chan->device);
> +		spin_lock(&d->lock);
> +		if (list_empty(&c->node))
> +			list_add_tail(&c->node, &d->pending);
> +		spin_unlock(&d->lock);
> +		tasklet_schedule(&d->task);
> +	}
> +	spin_unlock_irqrestore(&c->vc.lock, flags);
> +}
> +
> +
> +static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
> +	struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
> +	size_t period_len, enum dma_transfer_direction direction,
> +	unsigned long flags, void *context)
> +{
> +	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> +	enum dma_slave_buswidth dev_width;
> +	struct bcm2835_desc *d;
> +	dma_addr_t dev_addr;
> +	unsigned int es, sync_type, sync_dreq;
> +
> +	/* Grab configuration */
> +	if (direction == DMA_DEV_TO_MEM) {
> +		dev_addr = c->cfg.src_addr;
> +		dev_width = c->cfg.src_addr_width;
> +		sync_type = BCM2835_DMA_S_DREQ;
> +		sync_dreq = c->cfg.slave_id;
> +	} else if (direction == DMA_MEM_TO_DEV) {
> +		dev_addr = c->cfg.dst_addr;
> +		dev_width = c->cfg.dst_addr_width;
> +		sync_type = BCM2835_DMA_D_DREQ;
> +		sync_dreq = c->cfg.slave_id;
> +	} else {
> +		dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
> +		return NULL;
> +	}
> +
> +	/* Bus width translates to the element size (ES) */
> +	switch (dev_width) {
> +	case DMA_SLAVE_BUSWIDTH_4_BYTES:
> +		es = BCM2835_DMA_DATA_TYPE_S32;
> +		break;
> +	default:
> +		return NULL;
> +	}
> +
> +	/* Now allocate and setup the descriptor. */
> +	d = kzalloc(sizeof(*d) + sizeof(d->sg[0]), GFP_ATOMIC);
> +	if (!d)
> +		return NULL;
> +
> +	d->dir = direction;
> +	d->dev_addr = dev_addr;
> +	d->es = es;
> +	d->sync_type = sync_type;
> +	d->sync_dreq = sync_dreq;
> +	d->sg[0].addr = buf_addr;
> +	d->sg[0].en = period_len;
> +	d->sg[0].fn = buf_len / period_len;
> +	d->sglen = 1;
> +
> +	/* Allocate memory for control blocks */
> +	d->control_block_size = d->sg[0].fn*sizeof(struct bcm2835_dma_cb);
> +	d->control_block_base = dma_alloc_coherent(chan->device->dev,
> +			d->control_block_size, &d->control_block_base_phys,
> +			GFP_KERNEL);
> +
> +	if (!d->control_block_base) {
> +		dev_err(chan->device->dev,
> +				"%s: Memory allocation error\n", __func__);
> +		return NULL;
> +	}
> +
> +	memset(d->control_block_base, 0, d->control_block_size);
> +
> +	if (!c->cyclic) {
> +		c->cyclic = true;
> +		/* nothing else is implemented */
> +	}
> +
> +	return vchan_tx_prep(&c->vc, &d->vd, DMA_CTRL_ACK | DMA_PREP_INTERRUPT);
> +}
> +
> +static int bcm2835_dma_slave_config(struct bcm2835_chan *c,
> +		struct dma_slave_config *cfg)
> +{
> +	if ((cfg->direction == DMA_DEV_TO_MEM
> +			&& cfg->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) ||
> +	    (cfg->direction == DMA_MEM_TO_DEV
> +			&& cfg->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)) {
> +		return -EINVAL;
> +	}
> +
> +	memcpy(&c->cfg, cfg, sizeof(c->cfg));
> +
> +	return 0;
> +}
> +
> +static int bcm2835_dma_terminate_all(struct bcm2835_chan *c)
> +{
> +	struct bcm2835_dmadev *d = to_bcm2835_dma_dev(c->vc.chan.device);
> +	unsigned long flags;
> +	LIST_HEAD(head);
> +
> +	spin_lock_irqsave(&c->vc.lock, flags);
> +
> +	/* Prevent this channel being scheduled */
> +	spin_lock(&d->lock);
> +	list_del_init(&c->node);
> +	spin_unlock(&d->lock);
> +
> +	/*
> +	 * Stop DMA activity: we assume the callback will not be called
> +	 * after bcm_dma_abort() returns (even if it does, it will see
> +	 * c->desc is NULL and exit.)
> +	 */
> +	if (c->desc) {
> +		c->desc = NULL;
> +		bcm2835_dma_abort(c->dma_chan_base);
> +
> +		/* Wait for stopping */
> +		while (readl(c->dma_chan_base + BCM2835_DMA_CS)
> +			& BCM2835_DMA_ACTIVE)
> +			;
> +	}
> +
> +	vchan_get_all_descriptors(&c->vc, &head);
> +	spin_unlock_irqrestore(&c->vc.lock, flags);
> +	vchan_dma_desc_free_list(&c->vc, &head);
> +
> +	return 0;
> +}
> +
> +static int bcm2835_dma_pause(struct bcm2835_chan *c)
> +{
> +	/* FIXME: not supported by platform private API */
> +	return -EINVAL;
> +}
> +
> +static int bcm2835_dma_resume(struct bcm2835_chan *c)
> +{
> +	/* FIXME: not supported by platform private API */
> +	return -EINVAL;
> +}
> +
> +static int bcm2835_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> +	unsigned long arg)
> +{
> +	struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> +	int ret;
> +
> +	switch (cmd) {
> +	case DMA_SLAVE_CONFIG:
> +		ret = bcm2835_dma_slave_config(c,
> +				(struct dma_slave_config *)arg);
> +		break;
> +
> +	case DMA_TERMINATE_ALL:
> +		ret = bcm2835_dma_terminate_all(c);
> +		break;
> +
> +	case DMA_PAUSE:
> +		ret = bcm2835_dma_pause(c);
> +		break;
> +
> +	case DMA_RESUME:
> +		ret = bcm2835_dma_resume(c);
> +		break;
> +
> +	default:
> +		ret = -ENXIO;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int bcm2835_dma_chan_init(struct bcm2835_dmadev *od, int dma_sig)
> +{
> +	struct bcm2835_chan *c;
> +
> +	c = kzalloc(sizeof(*c), GFP_KERNEL);
> +	if (!c)
> +		return -ENOMEM;
> +
> +	c->dma_sig = dma_sig;
> +	c->vc.desc_free = bcm2835_dma_desc_free;
> +	vchan_init(&c->vc, &od->ddev);
> +	INIT_LIST_HEAD(&c->node);
> +
> +	od->ddev.chancnt++;
> +
> +	return 0;
> +}
> +
> +static void bcm2835_dma_free(struct bcm2835_dmadev *od)
> +{
> +	tasklet_kill(&od->task);
> +	while (!list_empty(&od->ddev.channels)) {
> +		struct bcm2835_chan *c = list_first_entry(&od->ddev.channels,
> +			struct bcm2835_chan, vc.chan.device_node);
> +
> +		list_del(&c->vc.chan.device_node);
> +		tasklet_kill(&c->vc.task);
> +		kfree(c);
> +	}
> +}
> +
> +#if defined(CONFIG_OF)
> +static const struct of_device_id bcm2835_dma_of_match[] = {
> +	{
> +		.compatible = "brcm,bcm2835-dma",
> +	}
> +};
> +MODULE_DEVICE_TABLE(of, bcm2835_dma_of_match);
> +#endif
> +
> +static int bcm2835_dma_probe(struct platform_device *pdev)
> +{
> +	struct bcm2835_dmadev *od;
> +	struct resource *dma_res = NULL;
> +	void __iomem *dma_base = NULL;
> +	int rc = 0;
> +	int i;
> +	struct resource *irq;
> +	int irq_resources;
> +
> +	od = devm_kzalloc(&pdev->dev, sizeof(*od), GFP_KERNEL);
> +	if (!od)
> +		return -ENOMEM;
> +
> +	dma_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	dma_base = devm_ioremap_resource(&pdev->dev, dma_res);
> +	if (IS_ERR(dma_base))
> +		return PTR_ERR(dma_base);
> +
> +	od->dma_base = dma_base;
> +	od->chans_available = BCM2835_DMA_CHANNEL_MASK;
> +
> +	dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
> +	dma_cap_set(DMA_CYCLIC, od->ddev.cap_mask);
> +	od->ddev.device_alloc_chan_resources = bcm2835_dma_alloc_chan_resources;
> +	od->ddev.device_free_chan_resources = bcm2835_dma_free_chan_resources;
> +	od->ddev.device_tx_status = bcm2835_dma_tx_status;
> +	od->ddev.device_issue_pending = bcm2835_dma_issue_pending;
> +	od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic;
> +	od->ddev.device_control = bcm2835_dma_control;
> +	od->ddev.dev = &pdev->dev;
> +	INIT_LIST_HEAD(&od->ddev.channels);
> +	INIT_LIST_HEAD(&od->pending);
> +	spin_lock_init(&od->lock);
> +
> +	tasklet_init(&od->task, bcm2835_dma_sched, (unsigned long)od);
> +
> +	irq_resources = 0;
> +
> +	for (i = 0; i < pdev->num_resources; i++) {
> +		if (IORESOURCE_IRQ == resource_type(&pdev->resource[i]))
> +			irq_resources++;
> +	}
> +
> +	od->dma_irq_numbers = devm_kzalloc(&pdev->dev,
> +			irq_resources*sizeof(int), GFP_KERNEL);
> +	if (!od)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < irq_resources; i++) {
> +		rc = bcm2835_dma_chan_init(od, i);
> +		if (rc) {
> +			bcm2835_dma_free(od);
> +			return rc;
> +		}
> +
> +		irq = platform_get_resource(pdev, IORESOURCE_IRQ, i);
> +		if (!irq) {
> +			dev_err(&pdev->dev,
> +					"No IRQ resource for channel %i\n", i);
> +			return -ENODEV;
> +		}
> +		od->dma_irq_numbers[i] = irq->start;
> +	}
> +
> +	rc = dma_async_device_register(&od->ddev);
> +	if (rc) {
> +		dev_err(&pdev->dev,
> +			"Failed to register slave DMA engine device: %d\n", rc);
> +		bcm2835_dma_free(od);
> +		return rc;
> +	}
> +
> +	platform_set_drvdata(pdev, od);
> +
> +	if (pdev->dev.of_node) {
> +		bcm2835_dma_info.dma_cap = od->ddev.cap_mask;
> +
> +		/* Device-tree DMA controller registration */
> +		rc = of_dma_controller_register(pdev->dev.of_node,
> +				of_dma_simple_xlate, &bcm2835_dma_info);
> +		if (rc) {
> +			dev_err(&pdev->dev, "Failed to register DMA controller\n");
> +			dma_async_device_unregister(&od->ddev);
> +			bcm2835_dma_free(od);
> +			return rc;
> +		}
> +	}
> +
> +	dev_dbg(&pdev->dev, "Load BCM2835 DMA engine driver\n");
> +
> +	return rc;
> +}
> +
> +static int bcm2835_dma_remove(struct platform_device *pdev)
> +{
> +	struct bcm2835_dmadev *od = platform_get_drvdata(pdev);
> +
> +	dma_async_device_unregister(&od->ddev);
> +	bcm2835_dma_free(od);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver bcm2835_dma_driver = {
> +	.probe	= bcm2835_dma_probe,
> +	.remove	= bcm2835_dma_remove,
> +	.driver = {
> +		.name = "bcm2835-dma",
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(bcm2835_dma_of_match),
> +	},
> +};
> +
> +static const struct platform_device_info bcm2835_dma_dev_info = {
> +	.name = "bcm2835-dma",
> +	.id = -1,
> +	.dma_mask = DMA_BIT_MASK(32),
> +};
> +
> +static int bcm2835_dma_init(void)
> +{
> +	int rc = platform_driver_register(&bcm2835_dma_driver);
> +	return rc;
> +}
> +subsys_initcall(bcm2835_dma_init);
> +
> +static void __exit bcm2835_dma_exit(void)
> +{
> +	platform_driver_unregister(&bcm2835_dma_driver);
> +}
> +module_exit(bcm2835_dma_exit);
> +
> +MODULE_AUTHOR("Florian Meier");
> +MODULE_DESCRIPTION("BCM2835 DMA engine driver");
> +MODULE_LICENSE("GPL");
> +
> -- 
> 1.7.9.5
> 
> 

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