Date:	Thu, 12 Dec 2013 11:16:57 +0200
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Jonas Jensen <jonas.jensen@...il.com>
Cc:	dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, arm@...nel.org, vinod.koul@...el.com,
	djbw@...com, arnd@...db.de, linux@....linux.org.uk,
	mark.rutland@....com, lars@...afoo.de
Subject: Re: [PATCH v13] dmaengine: Add MOXA ART DMA engine driver

On Wed, 2013-12-11 at 16:13 +0100, Jonas Jensen wrote:
> The MOXA ART SoC has a DMA controller capable of offloading expensive
> memory operations, such as large copies. This patch adds support for
> the controller including four channels. Two of these are used to
> handle MMC copy on the UC-7112-LX hardware. The remaining two can be
> used in a future audio driver or client application.
> 

Thanks for an update.

Since you will have next version anyway (addressing Arnd's comment) I
add my few minor comments below.

[]

> +++ b/drivers/dma/moxart-dma.c
> @@ -0,0 +1,729 @@
> +/*
> + * MOXA ART SoCs DMA Engine support.
> + *
> + * Copyright (C) 2013 Jonas Jensen
> + *
> + * Jonas Jensen <jonas.jensen@...il.com>
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2.  This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#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/spinlock.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_dma.h>
> +#include <linux/bitops.h>
> +
> +#include <asm/cacheflush.h>
> +
> +#include "dmaengine.h"
> +#include "virt-dma.h"
> +
> +#define APB_DMA_MAX_CHANNEL			4
> +
> +#define REG_OFF_ADDRESS_SOURCE			0
> +#define REG_OFF_ADDRESS_DEST			4
> +#define REG_OFF_CYCLES				8
> +#define REG_OFF_CTRL				12
> +#define REG_OFF_CHAN_SIZE			16
> +
> +#define APB_DMA_ENABLE				BIT(0)
> +#define APB_DMA_FIN_INT_STS			BIT(1)
> +#define APB_DMA_FIN_INT_EN			BIT(2)
> +#define APB_DMA_BURST_MODE			BIT(3)
> +#define APB_DMA_ERR_INT_STS			BIT(4)
> +#define APB_DMA_ERR_INT_EN			BIT(5)
> +


> +/*
> + * unset: APB, set: AHB
> + */

One line?

> +#define APB_DMA_SOURCE_SELECT			0x40
> +
> +/*
> + * unset: APB, set: AHB
> + */

Ditto.

> +#define APB_DMA_DEST_SELECT			0x80
> +
> +#define APB_DMA_SOURCE				0x100
> +#define APB_DMA_SOURCE_MASK			0x700
> +/*
> + * 000: no increment
> + * 001: +1 (busrt=0), +4  (burst=1)
> + * 010: +2 (burst=0), +8  (burst=1)
> + * 011: +4 (burst=0), +16 (burst=1)
> + * 101: -1 (burst=0), -4  (burst=1)
> + * 110: -2 (burst=0), -8  (burst=1)
> + * 111: -4 (burst=0), -16 (burst=1)
> + */
> +#define APB_DMA_SOURCE_INC_0			0
> +#define APB_DMA_SOURCE_INC_1_4			0x100
> +#define APB_DMA_SOURCE_INC_2_8			0x200
> +#define APB_DMA_SOURCE_INC_4_16			0x300
> +#define APB_DMA_SOURCE_DEC_1_4			0x500
> +#define APB_DMA_SOURCE_DEC_2_8			0x600
> +#define APB_DMA_SOURCE_DEC_4_16			0x700
> +
> +#define APB_DMA_DEST				0x1000
> +#define APB_DMA_DEST_MASK			0x7000
> +/*
> + * 000: no increment
> + * 001: +1 (busrt=0), +4  (burst=1)
> + * 010: +2 (burst=0), +8  (burst=1)
> + * 011: +4 (burst=0), +16 (burst=1)
> + * 101: -1 (burst=0), -4  (burst=1)
> + * 110: -2 (burst=0), -8  (burst=1)
> + * 111: -4 (burst=0), -16 (burst=1)
> +*/
> +#define APB_DMA_DEST_INC_0			0
> +#define APB_DMA_DEST_INC_1_4			0x1000
> +#define APB_DMA_DEST_INC_2_8			0x2000
> +#define APB_DMA_DEST_INC_4_16			0x3000
> +#define APB_DMA_DEST_DEC_1_4			0x5000
> +#define APB_DMA_DEST_DEC_2_8			0x6000
> +#define APB_DMA_DEST_DEC_4_16			0x7000
> +
> +/*
> + * Request signal select source/destination
> + * address for DMA hardware handshake.
> + *
> + * The request line number is a property of
> + * the DMA controller itself, e.g. MMC must
> + * always request channels where
> + * dma_slave_config->slave_id is 5.

For me it seems that text too squeezed here. The width of 72-76 symbols
sounds better.

> + *
> + * 0:    no request / grant signal
> + * 1-15: request    / grant signal
> + */
> +#define APB_DMA_DEST_REQ_NO			0x10000
> +#define APB_DMA_DEST_REQ_NO_MASK		0xf0000
> +#define APB_DMA_SOURCE_REQ_NO			0x1000000
> +#define APB_DMA_SOURCE_REQ_NO_MASK		0xf000000
> +
> +#define APB_DMA_DATA_WIDTH			0x100000
> +#define APB_DMA_DATA_WIDTH_MASK			0x300000
> +/*
> + * Data width of transfer:

Might be better to keep style across comments. I mean capital letter,
commas, dots, etc.

Check entire code for this.

> + *
> + * 00: word
> + * 01: half
> + * 10: byte
> + */
> +#define APB_DMA_DATA_WIDTH_4			0
> +#define APB_DMA_DATA_WIDTH_2			0x100000
> +#define APB_DMA_DATA_WIDTH_1			0x200000
> +
> +#define APB_DMA_CYCLES_MASK			0x00ffffff
> +
> +#define MOXART_DMA_DATA_TYPE_S8			0x00
> +#define MOXART_DMA_DATA_TYPE_S16		0x01
> +#define MOXART_DMA_DATA_TYPE_S32		0x02
> +
> +struct moxart_sg {
> +	dma_addr_t addr;
> +	uint32_t len;
> +};
> +
> +struct moxart_desc {
> +	enum dma_transfer_direction	dma_dir;
> +	dma_addr_t			dev_addr;
> +	unsigned int			sglen;
> +	unsigned int			dma_cycles;
> +	struct virt_dma_desc		vd;
> +	uint8_t				es;
> +	struct moxart_sg		sg[0];
> +};
> +
> +struct moxart_chan {
> +	struct virt_dma_chan		vc;
> +
> +	void __iomem			*base;
> +	struct moxart_desc		*desc;
> +
> +	struct dma_slave_config		cfg;
> +
> +	bool				allocated;
> +	bool				error;
> +	int				ch_num;
> +	unsigned int			line_reqno;
> +	unsigned int			sgidx;
> +};
> +
> +struct moxart_dmadev {
> +	struct dma_device		dma_slave;
> +	struct moxart_chan		slave_chans[APB_DMA_MAX_CHANNEL];
> +};
> +
> +struct moxart_filter_data {
> +	struct moxart_dmadev		*mdc;
> +	struct of_phandle_args		*dma_spec;
> +};
> +
> +static const unsigned es_bytes[] = {
> +	[MOXART_DMA_DATA_TYPE_S8] = 1,
> +	[MOXART_DMA_DATA_TYPE_S16] = 2,
> +	[MOXART_DMA_DATA_TYPE_S32] = 4,
> +};
> +
> +static struct device *chan2dev(struct dma_chan *chan)
> +{
> +	return &chan->dev->device;
> +}
> +
> +static inline struct moxart_chan *to_moxart_dma_chan(struct dma_chan *c)
> +{
> +	return container_of(c, struct moxart_chan, vc.chan);
> +}
> +
> +static inline struct moxart_desc *to_moxart_dma_desc(
> +	struct dma_async_tx_descriptor *t)
> +{
> +	return container_of(t, struct moxart_desc, vd.tx);
> +}
> +
> +static void moxart_dma_desc_free(struct virt_dma_desc *vd)
> +{
> +	kfree(container_of(vd, struct moxart_desc, vd));
> +}
> +
> +static int moxart_terminate_all(struct dma_chan *chan)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +	unsigned long flags;
> +	LIST_HEAD(head);
> +	u32 ctrl;
> +
> +	dev_dbg(chan2dev(chan), "%s: ch=%p\n", __func__, ch);
> +
> +	spin_lock_irqsave(&ch->vc.lock, flags);
> +
> +	if (ch->desc)
> +		ch->desc = NULL;
> +
> +	ctrl = readl(ch->base + REG_OFF_CTRL);
> +	ctrl &= ~(APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
> +	writel(ctrl, ch->base + REG_OFF_CTRL);
> +
> +	vchan_get_all_descriptors(&ch->vc, &head);
> +	spin_unlock_irqrestore(&ch->vc.lock, flags);
> +	vchan_dma_desc_free_list(&ch->vc, &head);
> +
> +	return 0;
> +}
> +
> +static int moxart_slave_config(struct dma_chan *chan,
> +			       struct dma_slave_config *cfg)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +	u32 ctrl;
> +
> +	ch->cfg = *cfg;
> +
> +	ctrl = readl(ch->base + REG_OFF_CTRL);
> +	ctrl |= APB_DMA_BURST_MODE;
> +	ctrl &= ~(APB_DMA_DEST_MASK | APB_DMA_SOURCE_MASK);
> +	ctrl &= ~(APB_DMA_DEST_REQ_NO_MASK | APB_DMA_SOURCE_REQ_NO_MASK);
> +
> +	switch (ch->cfg.src_addr_width) {
> +	case DMA_SLAVE_BUSWIDTH_1_BYTE:
> +		ctrl |= APB_DMA_DATA_WIDTH_1;
> +		if (ch->cfg.direction != DMA_MEM_TO_DEV)
> +			ctrl |= APB_DMA_DEST_INC_1_4;
> +		else
> +			ctrl |= APB_DMA_SOURCE_INC_1_4;
> +		break;
> +	case DMA_SLAVE_BUSWIDTH_2_BYTES:
> +		ctrl |= APB_DMA_DATA_WIDTH_2;
> +		if (ch->cfg.direction != DMA_MEM_TO_DEV)
> +			ctrl |= APB_DMA_DEST_INC_2_8;
> +		else
> +			ctrl |= APB_DMA_SOURCE_INC_2_8;
> +		break;
> +	case DMA_SLAVE_BUSWIDTH_4_BYTES:
> +		ctrl &= ~APB_DMA_DATA_WIDTH;
> +		if (ch->cfg.direction != DMA_MEM_TO_DEV)
> +			ctrl |= APB_DMA_DEST_INC_4_16;
> +		else
> +			ctrl |= APB_DMA_SOURCE_INC_4_16;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (ch->cfg.direction == DMA_MEM_TO_DEV) {
> +		ctrl &= ~APB_DMA_DEST_SELECT;
> +		ctrl |= APB_DMA_SOURCE_SELECT;
> +		ctrl |= (ch->line_reqno << 16 &
> +			 APB_DMA_DEST_REQ_NO_MASK);
> +	} else {
> +		ctrl |= APB_DMA_DEST_SELECT;
> +		ctrl &= ~APB_DMA_SOURCE_SELECT;
> +		ctrl |= (ch->line_reqno << 24 &
> +			 APB_DMA_SOURCE_REQ_NO_MASK);
> +	}
> +
> +	writel(ctrl, ch->base + REG_OFF_CTRL);
> +
> +	return 0;
> +}
> +
> +static int moxart_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> +			  unsigned long arg)
> +{
> +	int ret = 0;
> +
> +	switch (cmd) {
> +	case DMA_PAUSE:
> +	case DMA_RESUME:
> +		return -EINVAL;
> +	case DMA_TERMINATE_ALL:
> +		moxart_terminate_all(chan);
> +		break;
> +	case DMA_SLAVE_CONFIG:
> +		ret = moxart_slave_config(chan, (struct dma_slave_config *)arg);
> +		break;
> +	default:
> +		ret = -ENOSYS;
> +	}
> +
> +	return ret;
> +}
> +
> +static struct dma_async_tx_descriptor *moxart_prep_slave_sg(
> +	struct dma_chan *chan, struct scatterlist *sgl,
> +	unsigned int sg_len, enum dma_transfer_direction dir,
> +	unsigned long tx_flags, void *context)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +	struct moxart_desc *d;
> +	enum dma_slave_buswidth dev_width;
> +	dma_addr_t dev_addr;
> +	struct scatterlist *sgent;

> +	unsigned int es, i;

Could you split to two lines since the variables are from different
classes of application?

> +
> +	if (!is_slave_direction(dir)) {
> +		dev_err(chan2dev(chan), "%s: invalid DMA direction\n",
> +			__func__);
> +		return NULL;
> +	}
> +
> +	if (dir == DMA_DEV_TO_MEM) {
> +		dev_addr = ch->cfg.src_addr;
> +		dev_width = ch->cfg.src_addr_width;
> +	} else {
> +		dev_addr = ch->cfg.dst_addr;
> +		dev_width = ch->cfg.dst_addr_width;
> +	}
> +
> +	switch (dev_width) {
> +	case DMA_SLAVE_BUSWIDTH_1_BYTE:
> +		es = MOXART_DMA_DATA_TYPE_S8;
> +		break;
> +	case DMA_SLAVE_BUSWIDTH_2_BYTES:
> +		es = MOXART_DMA_DATA_TYPE_S16;
> +		break;
> +	case DMA_SLAVE_BUSWIDTH_4_BYTES:
> +		es = MOXART_DMA_DATA_TYPE_S32;
> +		break;
> +	default:
> +		dev_err(chan2dev(chan), "%s: unsupported data width (%u)\n",
> +			__func__, dev_width);
> +		return NULL;
> +	}
> +
> +	d = kzalloc(sizeof(*d) + sg_len * sizeof(d->sg[0]), GFP_ATOMIC);



> +	if (!d)
> +		return NULL;
> +
> +	d->dma_dir = dir;
> +	d->dev_addr = dev_addr;
> +	d->es = es;
> +
> +	for_each_sg(sgl, sgent, sg_len, i) {
> +		d->sg[i].addr = sg_dma_address(sgent);
> +		d->sg[i].len = sg_dma_len(sgent);
> +	}
> +
> +	d->sglen = sg_len;
> +
> +	ch->error = 0;
> +
> +	return vchan_tx_prep(&ch->vc, &d->vd, tx_flags);
> +}
> +
> +bool moxart_dma_filter_fn(struct dma_chan *chan, void *param)
> +{
> +	struct moxart_filter_data *fdata = param;
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +
> +	if (chan->device->dev != fdata->mdc->dma_slave.dev ||
> +	    chan->device->dev->of_node != fdata->dma_spec->np) {
> +		dev_dbg(chan2dev(chan), "device not registered to this DMA engine\n");
> +		return false;
> +	}
> +
> +	dev_dbg(chan2dev(chan), "%s: ch=%p line_reqno=%u ch->ch_num=%u\n",
> +		__func__, ch, fdata->dma_spec->args[0], ch->ch_num);
> +
> +	ch->line_reqno = fdata->dma_spec->args[0];
> +
> +	return true;
> +}
> +
> +static struct dma_chan *moxart_of_xlate(struct of_phandle_args *dma_spec,
> +					struct of_dma *ofdma)
> +{
> +	struct moxart_dmadev *mdc = ofdma->of_dma_data;
> +	struct moxart_filter_data fdata = {
> +		.mdc = mdc,
> +	};
> +
> +	if (dma_spec->args_count < 1)
> +		return NULL;
> +
> +	fdata.dma_spec = dma_spec;
> +
> +	return dma_request_channel(mdc->dma_slave.cap_mask,
> +				   moxart_dma_filter_fn, &fdata);
> +}
> +
> +static int moxart_alloc_chan_resources(struct dma_chan *chan)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +
> +	dev_dbg(chan2dev(chan), "%s: allocating channel #%u\n",
> +		__func__, ch->ch_num);
> +	ch->allocated = 1;
> +
> +	return 0;
> +}
> +
> +static void moxart_free_chan_resources(struct dma_chan *chan)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +
> +	vchan_free_chan_resources(&ch->vc);
> +
> +	dev_dbg(chan2dev(chan), "%s: freeing channel #%u\n",
> +		__func__, ch->ch_num);
> +	ch->allocated = 0;
> +}
> +
> +static void moxart_dma_set_params(struct moxart_chan *ch, dma_addr_t src_addr,
> +				  dma_addr_t dst_addr)
> +{
> +	writel(src_addr, ch->base + REG_OFF_ADDRESS_SOURCE);
> +	writel(dst_addr, ch->base + REG_OFF_ADDRESS_DEST);
> +}
> +
> +static void moxart_set_transfer_params(struct moxart_chan *ch, unsigned int len)
> +{
> +	struct moxart_desc *d = ch->desc;
> +	unsigned int sglen_div = es_bytes[d->es];
> +
> +	d->dma_cycles = len >> sglen_div;
> +
> +	/*
> +	 * cycles is 4 on 64 bytes copied, i.e. one cycle copies 16 bytes
> +	 * ( when width is APB_DMAB_DATA_WIDTH_4 )
> +	 */
> +	writel(d->dma_cycles, ch->base + REG_OFF_CYCLES);
> +
> +	dev_dbg(chan2dev(&ch->vc.chan), "%s: set %u DMA cycles (len=%u)\n",
> +		__func__, d->dma_cycles, len);
> +}
> +
> +static void moxart_start_dma(struct moxart_chan *ch)
> +{
> +	u32 ctrl;
> +
> +	ctrl = readl(ch->base + REG_OFF_CTRL);
> +	ctrl |= (APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
> +	writel(ctrl, ch->base + REG_OFF_CTRL);
> +}
> +
> +static void moxart_dma_start_sg(struct moxart_chan *ch, unsigned int idx)
> +{
> +	struct moxart_desc *d = ch->desc;
> +	struct moxart_sg *sg = ch->desc->sg + idx;
> +
> +	if (ch->desc->dma_dir == DMA_MEM_TO_DEV)
> +		moxart_dma_set_params(ch, sg->addr, d->dev_addr);
> +	else if (ch->desc->dma_dir == DMA_DEV_TO_MEM)
> +		moxart_dma_set_params(ch, d->dev_addr, sg->addr);
> +
> +	moxart_set_transfer_params(ch, sg->len);
> +
> +	moxart_start_dma(ch);
> +}
> +
> +static void moxart_dma_start_desc(struct dma_chan *chan)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +	struct virt_dma_desc *vd;
> +
> +	vd = vchan_next_desc(&ch->vc);
> +
> +	if (!vd) {
> +		ch->desc = NULL;
> +		return;
> +	}
> +
> +	list_del(&vd->node);
> +
> +	ch->desc = to_moxart_dma_desc(&vd->tx);
> +	ch->sgidx = 0;
> +
> +	moxart_dma_start_sg(ch, 0);
> +}
> +
> +static void moxart_issue_pending(struct dma_chan *chan)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&ch->vc.lock, flags);
> +	if (vchan_issue_pending(&ch->vc) && !ch->desc)
> +		moxart_dma_start_desc(chan);
> +	spin_unlock_irqrestore(&ch->vc.lock, flags);
> +}
> +
> +static size_t moxart_dma_desc_size(struct moxart_desc *d)
> +{
> +	unsigned i;
> +	size_t size;
> +
> +	for (size = i = 0; i < d->sglen; i++)
> +		size += d->sg[i].len;
> +
> +	return size;
> +}
> +
> +static size_t moxart_dma_desc_size_in_flight(struct moxart_chan *ch)
> +{
> +	size_t size;
> +	unsigned int completed_cycles, cycles;
> +
> +	cycles = readl(ch->base + REG_OFF_CYCLES);
> +	size = moxart_dma_desc_size(ch->desc);
> +	completed_cycles = (ch->desc->dma_cycles - cycles);
> +	size -= completed_cycles << es_bytes[ch->desc->es];
> +
> +	dev_dbg(chan2dev(&ch->vc.chan), "%s: size=%zd\n", __func__, size);

Sorry, I was a bit inaccurate here.

ssize_t (signed type) -> %zd
size_t (unsigned type) -> %zu

Please, fix this.

> +
> +	return size;
> +}
> +
> +static enum dma_status moxart_tx_status(struct dma_chan *chan,
> +					dma_cookie_t cookie,
> +					struct dma_tx_state *txstate)
> +{
> +	struct moxart_chan *ch = to_moxart_dma_chan(chan);
> +	struct virt_dma_desc *vd;
> +	struct moxart_desc *d;
> +	enum dma_status ret;
> +	unsigned long flags;
> +
> +	/*
> +	 * dma_cookie_status assigns initial residue value
> +	 */
> +	ret = dma_cookie_status(chan, cookie, txstate);
> +
> +	spin_lock_irqsave(&ch->vc.lock, flags);
> +	vd = vchan_find_desc(&ch->vc, cookie);
> +	if (vd) {
> +		d = to_moxart_dma_desc(&vd->tx);
> +		txstate->residue = moxart_dma_desc_size(d);
> +	} else if (ch->desc && ch->desc->vd.tx.cookie == cookie) {
> +		txstate->residue = moxart_dma_desc_size_in_flight(ch);
> +	}
> +	spin_unlock_irqrestore(&ch->vc.lock, flags);
> +
> +	if (ch->error)
> +		return DMA_ERROR;
> +
> +	return ret;
> +}
> +
> +static void moxart_dma_init(struct dma_device *dma, struct device *dev)
> +{
> +	dma->device_prep_slave_sg		= moxart_prep_slave_sg;
> +	dma->device_alloc_chan_resources	= moxart_alloc_chan_resources;
> +	dma->device_free_chan_resources		= moxart_free_chan_resources;
> +	dma->device_issue_pending		= moxart_issue_pending;
> +	dma->device_tx_status			= moxart_tx_status;
> +	dma->device_control			= moxart_control;
> +	dma->dev				= dev;
> +
> +	INIT_LIST_HEAD(&dma->channels);
> +}
> +
> +static irqreturn_t moxart_dma_interrupt(int irq, void *devid)
> +{
> +	struct moxart_dmadev *mc = devid;
> +	struct moxart_chan *ch = &mc->slave_chans[0];
> +	unsigned int i;
> +	unsigned long flags;
> +	u32 ctrl;
> +
> +	dev_dbg(chan2dev(&ch->vc.chan), "%s\n", __func__);
> +
> +	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
> +		if (!ch->allocated)
> +			continue;
> +
> +		ctrl = readl(ch->base + REG_OFF_CTRL);
> +
> +		dev_dbg(chan2dev(&ch->vc.chan), "%s: ch=%p ch->base=%p ctrl=%x\n",
> +			__func__, ch, ch->base, ctrl);
> +
> +		if (ctrl & APB_DMA_FIN_INT_STS) {
> +			ctrl &= ~APB_DMA_FIN_INT_STS;
> +			if (ch->desc) {
> +				spin_lock_irqsave(&ch->vc.lock, flags);
> +				if (++ch->sgidx < ch->desc->sglen)
> +					moxart_dma_start_sg(ch, ch->sgidx);


> +				else {

} else {

If you use {} in one branch you have to use it in the other accordingly
to coding style.

> +					vchan_cookie_complete(&ch->desc->vd);
> +					ch->desc = NULL;
> +				}
> +				spin_unlock_irqrestore(&ch->vc.lock, flags);
> +			}
> +		}
> +
> +		if (ctrl & APB_DMA_ERR_INT_STS) {
> +			ctrl &= ~APB_DMA_ERR_INT_STS;
> +			ch->error = 1;
> +		}
> +
> +		writel(ctrl, ch->base + REG_OFF_CTRL);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int moxart_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *node = dev->of_node;
> +	struct resource *res;
> +	static void __iomem *dma_base_addr;
> +	int ret, i;
> +	unsigned int irq;
> +	struct moxart_chan *ch;
> +	struct moxart_dmadev *mdc;
> +
> +	mdc = devm_kzalloc(dev, sizeof(*mdc), GFP_KERNEL);
> +	if (!mdc) {
> +		dev_err(dev, "can't allocate DMA container\n");
> +		return -ENOMEM;
> +	}
> +
> +	irq = irq_of_parse_and_map(node, 0);
> +	if (irq <= 0) {

This one is not correct. It will never be negative (see the variable
type). IIUC, you have to check against 0 only.

> +		dev_err(dev, "irq_of_parse_and_map failed\n");
> +		return -EINVAL;
> +	}
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	dma_base_addr = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(dma_base_addr))
> +		return PTR_ERR(dma_base_addr);
> +
> +	dma_cap_zero(mdc->dma_slave.cap_mask);
> +	dma_cap_set(DMA_SLAVE, mdc->dma_slave.cap_mask);
> +
> +	moxart_dma_init(&mdc->dma_slave, dev);
> +
> +	ch = &mdc->slave_chans[0];
> +	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
> +		ch->ch_num = i;
> +		ch->base = dma_base_addr + i * REG_OFF_CHAN_SIZE;
> +		ch->allocated = 0;
> +
> +		ch->vc.desc_free = moxart_dma_desc_free;
> +		vchan_init(&ch->vc, &mdc->dma_slave);
> +
> +		dev_dbg(dev, "%s: chs[%d]: ch->ch_num=%u ch->base=%p\n",
> +			__func__, i, ch->ch_num, ch->base);
> +	}
> +
> +	platform_set_drvdata(pdev, mdc);
> +
> +	ret = devm_request_irq(dev, irq, moxart_dma_interrupt, 0,
> +			       "moxart-dma-engine", mdc);
> +	if (ret) {
> +		dev_err(dev, "devm_request_irq failed\n");
> +		return ret;
> +	}
> +
> +	ret = dma_async_device_register(&mdc->dma_slave);
> +	if (ret) {
> +		dev_err(dev, "dma_async_device_register failed\n");
> +		return ret;
> +	}
> +
> +	ret = of_dma_controller_register(node, moxart_of_xlate, mdc);
> +	if (ret) {
> +		dev_err(dev, "of_dma_controller_register failed\n");
> +		dma_async_device_unregister(&mdc->dma_slave);
> +		return ret;
> +	}
> +
> +	dev_dbg(dev, "%s: IRQ=%u\n", __func__, irq);
> +
> +	return 0;
> +}
> +
> +static int moxart_remove(struct platform_device *pdev)
> +{
> +	struct moxart_dmadev *m = platform_get_drvdata(pdev);
> +
> +	dma_async_device_unregister(&m->dma_slave);
> +
> +	if (pdev->dev.of_node)
> +		of_dma_controller_free(pdev->dev.of_node);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id moxart_dma_match[] = {
> +	{ .compatible = "moxa,moxart-dma" },
> +	{ }
> +};
> +
> +static struct platform_driver moxart_driver = {
> +	.probe	= moxart_probe,
> +	.remove	= moxart_remove,
> +	.driver = {
> +		.name		= "moxart-dma-engine",
> +		.owner		= THIS_MODULE,
> +		.of_match_table	= moxart_dma_match,
> +	},
> +};
> +
> +static int moxart_init(void)
> +{
> +	return platform_driver_register(&moxart_driver);
> +}
> +subsys_initcall(moxart_init);
> +
> +static void __exit moxart_exit(void)
> +{
> +	platform_driver_unregister(&moxart_driver);
> +}
> +module_exit(moxart_exit);
> +
> +MODULE_AUTHOR("Jonas Jensen <jonas.jensen@...il.com>");
> +MODULE_DESCRIPTION("MOXART DMA engine driver");
> +MODULE_LICENSE("GPL v2");

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy

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