[4/5] DMA: sun6i: Add driver for the Allwinner A31 DMA controller

Commit Message

Maxime Ripard Feb. 24, 2014, 4:22 p.m. UTC

The Allwinner A31 has a 16 channels DMA controller that it shares with the
newer A23. Although sharing some similarities with the DMA controller of the
older Allwinner SoCs, it's significantly different, I don't expect it to be
possible to share the driver for these two.

The A31 Controller is able to memory-to-memory or memory-to-device transfers on
the 16 channels in parallel.

Signed-off-by: Maxime Ripard <[e-mail]>
---
 .../devicetree/bindings/dma/sun6i-dma.txt          |  45 +
 drivers/dma/Kconfig                                |   8 +
 drivers/dma/Makefile                               |   1 +
 drivers/dma/sun6i-dma.c                            | 960 +++++++++++++++++++++
 4 files changed, 1014 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/sun6i-dma.txt
 create mode 100644 drivers/dma/sun6i-dma.c

Comments

Andy Shevchenko Feb. 25, 2014, 11:28 a.m. UTC | #1

On Mon, 2014-02-24 at 17:22 +0100, Maxime Ripard wrote:
> The Allwinner A31 has a 16 channels DMA controller that it shares with the
> newer A23. Although sharing some similarities with the DMA controller of the
> older Allwinner SoCs, it's significantly different, I don't expect it to be
> possible to share the driver for these two.
> 
> The A31 Controller is able to memory-to-memory or memory-to-device transfers on
> the 16 channels in parallel.
> 
> Signed-off-by: Maxime Ripard <[e-mail]>
> ---
>  .../devicetree/bindings/dma/sun6i-dma.txt          |  45 +
>  drivers/dma/Kconfig                                |   8 +
>  drivers/dma/Makefile                               |   1 +
>  drivers/dma/sun6i-dma.c                            | 960 +++++++++++++++++++++
>  4 files changed, 1014 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/sun6i-dma.txt
>  create mode 100644 drivers/dma/sun6i-dma.c
> 
> diff --git a/Documentation/devicetree/bindings/dma/sun6i-dma.txt b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
> new file mode 100644
> index 0000000..5d7c86d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
> @@ -0,0 +1,45 @@
> +Allwinner A31 DMA Controller
> +
> +This driver follows the generic DMA bindings defined in dma.txt.
> +
> +Required properties:
> +
> +- compatible:	Must be "allwinner,sun6i-a31-dma"
> +- reg:		Should contain the registers base address and length
> +- interrupts:	Should contain a reference to the interrupt used by this device
> +- clocks:	Should contain a reference to the parent AHB clock
> +- resets:	Should contain a reference to the reset controller asserting
> +	  	this device in reset
> +- #dma-cells :	Should be 1, a single cell holding a line request number
> +
> +Example:
> +	dma: dma-controller@01c02000 {
> +		compatible = "allwinner,sun6i-a31-dma";
> +		reg = <0x01c02000 0x1000>;
> +		interrupts = <0 50 4>;
> +		clocks = <&ahb1_gates 6>;
> +		resets = <&ahb1_rst 6>;
> +		#dma-cells = <1>;
> +	};
> +
> +Clients:
> +
> +DMA clients connected to the A31 DMA controller must use the format
> +described in the dma.txt file, using a two-cell specifier for each
> +channel: a phandle plus one integer cells.
> +The two cells in order are:
> +
> +1. A phandle pointing to the DMA controller.
> +2. The port ID as specified in the datasheet
> +
> +Example:
> +spi2: spi@01c6a000 {
> +	compatible = "allwinner,sun6i-a31-spi";
> +	reg = <0x01c6a000 0x1000>;
> +	interrupts = <0 67 4>;
> +	clocks = <&ahb1_gates 22>, <&spi2_clk>;
> +	clock-names = "ahb", "mod";
> +	dmas = <&dma 25>, <&dma 25>;
> +	dma-names = "rx", "tx";
> +	resets = <&ahb1_rst 22>;
> +};
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 605b016..7923697 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -351,6 +351,14 @@ config MOXART_DMA
>  	help
>  	  Enable support for the MOXA ART SoC DMA controller.
>  
> +config DMA_SUN6I
> +	tristate "Allwinner A31 SoCs DMA support"
> +	depends on ARCH_SUNXI
> +	select DMA_ENGINE
> +	select DMA_VIRTUAL_CHANNELS
> +	help
> +	  Support for the DMA engine for Allwinner A31 SoCs.
> +
>  config DMA_ENGINE
>  	bool
>  
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index a029d0f4..18cdbad 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -44,3 +44,4 @@ obj-$(CONFIG_DMA_JZ4740) += dma-jz4740.o
>  obj-$(CONFIG_TI_CPPI41) += cppi41.o
>  obj-$(CONFIG_K3_DMA) += k3dma.o
>  obj-$(CONFIG_MOXART_DMA) += moxart-dma.o
> +obj-$(CONFIG_DMA_SUN6I) += sun6i-dma.o
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> new file mode 100644
> index 0000000..2649fde
> --- /dev/null
> +++ b/drivers/dma/sun6i-dma.c
> @@ -0,0 +1,960 @@
> +/*
> + * Copyright (C) 2013-2014 Allwinner Tech Co., Ltd
> + * Author: Sugar <[e-mail]>
> + *
> + * Copyright (C) 2014 Maxime Ripard
> + * Maxime Ripard <[e-mail]>
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dmapool.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/of_dma.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#include "virt-dma.h"
> +
> +/*
> + * There's 16 physical channels that can work in parallel.
> + *
> + * However we have 30 different endpoints for our requests.
> + *
> + * Since the channels are able to handle only an unidirectional
> + * transfer, we need to allocate more virtual channels so that
> + * everyone can grab one channel.
> + *
> + * Some devices can't work in both direction (mostly because it
> + * wouldn't make sense), so we have a bit fewer virtual channels than
> + * 2 channels per endpoints.
> + */
> +
> +#define NR_MAX_CHANNELS		16
> +#define NR_MAX_REQUESTS		30
> +#define NR_MAX_VCHANS		53
> +
> +/*
> + * Common registers
> + */
> +#define DMA_IRQ_EN(x)		((x) * 0x04)
> +#define DMA_IRQ_HALF			BIT(0)
> +#define DMA_IRQ_PKG			BIT(1)
> +#define DMA_IRQ_QUEUE			BIT(2)
> +
> +#define DMA_IRQ_CHAN_NR			8
> +#define DMA_IRQ_CHAN_WIDTH		4
> +
> +
> +#define DMA_IRQ_STAT(x)		((x) * 0x04 + 0x10)
> +
> +#define DMA_STAT		0x30
> +
> +/*
> + * Channels specific registers
> + */
> +#define DMA_CHAN_ENABLE		0x00
> +#define DMA_CHAN_ENABLE_START		BIT(0)
> +#define DMA_CHAN_ENABLE_STOP		0
> +
> +#define DMA_CHAN_PAUSE		0x04
> +#define DMA_CHAN_PAUSE_PAUSE		BIT(1)
> +#define DMA_CHAN_PAUSE_RESUME		0
> +
> +#define DMA_CHAN_LLI_ADDR	0x08
> +
> +#define DMA_CHAN_CUR_CFG	0x0c
> +#define DMA_CHAN_CFG_SRC_DRQ(x)		((x) & 0x1f)
> +#define DMA_CHAN_CFG_SRC_IO_MODE	BIT(5)
> +#define DMA_CHAN_CFG_SRC_LINEAR_MODE	(0 << 5)
> +#define DMA_CHAN_CFG_SRC_BURST(x)	(((x) & 0x3) << 7)
> +#define DMA_CHAN_CFG_SRC_WIDTH(x)	(((x) & 0x3) << 9)
> +
> +#define DMA_CHAN_CFG_DST_DRQ(x)		(DMA_CHAN_CFG_SRC_DRQ(x) << 16)
> +#define DMA_CHAN_CFG_DST_IO_MODE	(DMA_CHAN_CFG_SRC_IO_MODE << 16)
> +#define DMA_CHAN_CFG_DST_LINEAR_MODE	(DMA_CHAN_CFG_SRC_LINEAR_MODE << 16)
> +#define DMA_CHAN_CFG_DST_BURST(x)	(DMA_CHAN_CFG_SRC_BURST(x) << 16)
> +#define DMA_CHAN_CFG_DST_WIDTH(x)	(DMA_CHAN_CFG_SRC_WIDTH(x) << 16)
> +
> +#define DMA_CHAN_CUR_SRC	0x10
> +
> +#define DMA_CHAN_CUR_DST	0x14
> +
> +#define DMA_CHAN_CUR_CNT	0x18
> +
> +#define DMA_CHAN_CUR_PARA	0x1c
> +
> +
> +/*
> + * Various hardware related defines
> + */
> +#define LLI_LAST_ITEM	0xfffff800
> +#define NORMAL_WAIT	8
> +#define DRQ_SDRAM	1
> +
> +/*
> + * Hardware representation of the LLI
> + *
> + * The hardware will be fed the physical address of this structure,
> + * and read its content in order to start the transfer.
> + */
> +struct sun6i_dma_lli {
> +	u32			cfg;
> +	dma_addr_t		src;
> +	dma_addr_t		dst;
> +	u32			len;
> +	u32			para;
> +	dma_addr_t		p_lli_next;
> +	struct sun6i_dma_lli	*v_lli_next;
> +} __packed;

dma_addr_t could be different depending on platform configuration. If
your hardware is using constant length of those field I think would be
better to use something reliable in that case.

> +
> +
> +struct sun6i_desc {
> +	struct virt_dma_desc	vd;
> +	dma_addr_t		p_lli;
> +	struct sun6i_dma_lli	*v_lli;
> +};
> +
> +struct sun6i_pchan {
> +	u32			idx;
> +	void __iomem		*base;
> +	struct sun6i_vchan	*vchan;
> +	struct sun6i_desc	*desc;
> +	struct sun6i_desc	*done;
> +};
> +
> +struct sun6i_vchan {
> +	struct virt_dma_chan	vc;
> +	struct list_head	node;
> +	struct dma_slave_config	cfg;
> +	struct sun6i_pchan	*phy;
> +	u8			port;
> +};
> +
> +struct sun6i_dma_dev {
> +	struct dma_device	slave;
> +	void __iomem		*base;
> +	struct clk		*clk;
> +	struct reset_control	*rstc;
> +	spinlock_t		lock;
> +	struct tasklet_struct	task;
> +	struct list_head	pending;
> +	struct dma_pool		*pool;
> +	struct sun6i_pchan	*pchans;
> +	struct sun6i_vchan	*vchans;
> +};
> +
> +static struct device *chan2dev(struct dma_chan *chan)
> +{
> +	return &chan->dev->device;
> +}
> +
> +static inline struct sun6i_dma_dev *to_sun6i_dma_dev(struct dma_device *d)
> +{
> +	return container_of(d, struct sun6i_dma_dev, slave);
> +}
> +
> +static inline struct sun6i_vchan *to_sun6i_vchan(struct dma_chan *chan)
> +{
> +	return container_of(chan, struct sun6i_vchan, vc.chan);
> +}
> +
> +static inline struct sun6i_desc *
> +to_sun6i_desc(struct dma_async_tx_descriptor *tx)
> +{
> +	return container_of(tx, struct sun6i_desc, vd.tx);
> +}
> +
> +static inline void sun6i_dma_dump_com_regs(struct sun6i_dma_dev *sdev)
> +{
> +	pr_debug("Common register:\n"
> +		 "\tmask0(%04x): 0x%08x\n"
> +		 "\tmask1(%04x): 0x%08x\n"
> +		 "\tpend0(%04x): 0x%08x\n"
> +		 "\tpend1(%04x): 0x%08x\n"
> +		 "\tstats(%04x): 0x%08x\n",
> +		 DMA_IRQ_EN(0), readl(sdev->base + DMA_IRQ_EN(0)),
> +		 DMA_IRQ_EN(1), readl(sdev->base + DMA_IRQ_EN(1)),
> +		 DMA_IRQ_STAT(0), readl(sdev->base + DMA_IRQ_STAT(0)),
> +		 DMA_IRQ_STAT(1), readl(sdev->base + DMA_IRQ_STAT(1)),
> +		 DMA_STAT, readl(sdev->base + DMA_STAT));

dev_dbg() ?

> +}
> +
> +static inline void sun6i_dma_dump_chan_regs(struct sun6i_pchan *pchan)
> +{
> +	pr_debug("Chan %d reg: 0x%x\n"
> +		 "\t___en(%04x): \t0x%08x\n"
> +		 "\tpause(%04x): \t0x%08x\n"
> +		 "\tstart(%04x): \t0x%08x\n"
> +		 "\t__cfg(%04x): \t0x%08x\n"
> +		 "\t__src(%04x): \t0x%08x\n"
> +		 "\t__dst(%04x): \t0x%08x\n"
> +		 "\tcount(%04x): \t0x%08x\n"
> +		 "\t_para(%04x): \t0x%08x\n\n",
> +		 pchan->idx, __virt_to_phys((unsigned long)pchan->base),
> +		 DMA_CHAN_ENABLE,
> +		 readl(pchan->base + DMA_CHAN_ENABLE),
> +		 DMA_CHAN_PAUSE,
> +		 readl(pchan->base + DMA_CHAN_PAUSE),
> +		 DMA_CHAN_LLI_ADDR,
> +		 readl(pchan->base + DMA_CHAN_LLI_ADDR),
> +		 DMA_CHAN_CUR_CFG,
> +		 readl(pchan->base + DMA_CHAN_CUR_CFG),
> +		 DMA_CHAN_CUR_SRC,
> +		 readl(pchan->base + DMA_CHAN_CUR_SRC),
> +		 DMA_CHAN_CUR_DST,
> +		 readl(pchan->base + DMA_CHAN_CUR_DST),
> +		 DMA_CHAN_CUR_CNT,
> +		 readl(pchan->base + DMA_CHAN_CUR_CNT),
> +		 DMA_CHAN_CUR_PARA,
> +		 readl(pchan->base + DMA_CHAN_CUR_PARA));

Ditto.

> +}
> +
> +static inline u8 convert_burst(u8 maxburst)
> +{
> +	if (maxburst == 1 || maxburst > 16)
> +		return 0;
> +
> +	return ilog2(maxburst) - 1;

fls() - 1 ?

> +}
> +
> +static inline u8 convert_buswidth(enum dma_slave_buswidth addr_width)
> +{
> +	switch (addr_width) {
> +	case DMA_SLAVE_BUSWIDTH_2_BYTES:
> +		return 1;
> +	case DMA_SLAVE_BUSWIDTH_4_BYTES:
> +		return 2;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static void *sun6i_dma_lli_add(struct sun6i_dma_lli *prev,
> +			       struct sun6i_dma_lli *next,
> +			       dma_addr_t next_phy,
> +			       struct sun6i_desc *txd)
> +{
> +	if ((!prev && !txd) || !next)
> +		return NULL;
> +
> +	if (!prev) {
> +		txd->p_lli = next_phy;
> +		txd->v_lli = next;
> +	} else {
> +		prev->p_lli_next = next_phy;
> +		prev->v_lli_next = next;
> +	}
> +
> +	next->p_lli_next = LLI_LAST_ITEM;
> +	next->v_lli_next = NULL;
> +
> +	return next;
> +}
> +
> +static inline void sun6i_dma_cfg_lli(struct sun6i_dma_lli *lli,
> +				     dma_addr_t src,
> +				     dma_addr_t dst, u32 len,
> +				     struct dma_slave_config *config)
> +{
> +	u32 src_width, dst_width, src_burst, dst_burst;
> +
> +	if (!config)
> +		return;
> +
> +	src_burst = convert_burst(config->src_maxburst);
> +	dst_burst = convert_burst(config->dst_maxburst);
> +
> +	src_width = convert_buswidth(config->src_addr_width);
> +	dst_width = convert_buswidth(config->dst_addr_width);
> +
> +	lli->cfg = DMA_CHAN_CFG_SRC_BURST(src_burst) |
> +		DMA_CHAN_CFG_SRC_WIDTH(src_width) |
> +		DMA_CHAN_CFG_DST_BURST(dst_burst) |
> +		DMA_CHAN_CFG_DST_WIDTH(dst_width);
> +
> +	lli->src = src;
> +	lli->dst = dst;
> +	lli->len = len;
> +	lli->para = NORMAL_WAIT;
> +
> +}
> +
> +static inline void sun6i_dma_dump_lli(struct sun6i_vchan *vchan,
> +				      struct sun6i_dma_lli *lli)
> +{
> +	dev_dbg(chan2dev(&vchan->vc.chan),
> +		"\n\tdesc:   p - 0x%08x v - 0x%08x\n"
> +		"\t\tc - 0x%08x s - 0x%08x d - 0x%08x\n"
> +		"\t\tl - 0x%08x p - 0x%08x n - 0x%08x\n",
> +		__virt_to_phys((unsigned long)lli), (u32)lli,
> +		lli->cfg, lli->src, lli->dst,
> +		lli->len, lli->para, lli->p_lli_next);
> +}
> +
> +static void sun6i_dma_free_desc(struct virt_dma_desc *vd)
> +{
> +	struct sun6i_desc *txd = to_sun6i_desc(&vd->tx);
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vd->tx.chan->device);
> +	struct sun6i_dma_lli *v_lli, *v_next;
> +	dma_addr_t p_lli, p_next;
> +
> +	if (unlikely(!txd))
> +		return;
> +
> +	p_lli = txd->p_lli;
> +	v_lli = txd->v_lli;
> +
> +	while (v_lli) {
> +		v_next = v_lli->v_lli_next;
> +		p_next = v_lli->p_lli_next;
> +
> +		dma_pool_free(sdev->pool, v_lli, p_lli);
> +
> +		v_lli = v_next;
> +		p_lli = p_next;
> +	}
> +
> +	kfree(txd);
> +}
> +
> +static int sun6i_dma_terminate_all(struct sun6i_vchan *vchan)
> +{
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
> +	struct sun6i_pchan *pchan = vchan->phy;
> +	unsigned long flags;
> +	LIST_HEAD(head);
> +
> +	spin_lock(&sdev->lock);
> +	list_del_init(&vchan->node);
> +	spin_unlock(&sdev->lock);
> +
> +	spin_lock_irqsave(&vchan->vc.lock, flags);
> +
> +	vchan_get_all_descriptors(&vchan->vc, &head);
> +
> +	if (pchan) {
> +		writel(DMA_CHAN_ENABLE_STOP, pchan->base + DMA_CHAN_ENABLE);
> +		writel(DMA_CHAN_PAUSE_RESUME, pchan->base + DMA_CHAN_PAUSE);
> +
> +		vchan->phy = NULL;
> +		pchan->vchan = NULL;
> +		pchan->desc = NULL;
> +		pchan->done = NULL;
> +	}
> +
> +	spin_unlock_irqrestore(&vchan->vc.lock, flags);
> +
> +	vchan_dma_desc_free_list(&vchan->vc, &head);
> +
> +	return 0;
> +}
> +
> +static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
> +{
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
> +	struct virt_dma_desc *desc = vchan_next_desc(&vchan->vc);
> +	struct sun6i_pchan *pchan = vchan->phy;
> +	u32 irq_val, irq_reg, irq_offset;
> +
> +	if (!pchan)
> +		return -EAGAIN;
> +
> +	if (!desc) {
> +		pchan->desc = NULL;
> +		pchan->done = NULL;
> +		return -EAGAIN;
> +	}
> +
> +	list_del(&desc->node);
> +
> +	pchan->desc = to_sun6i_desc(&desc->tx);
> +	pchan->done = NULL;
> +
> +	sun6i_dma_dump_lli(vchan, pchan->desc->v_lli);
> +
> +	irq_reg = pchan->idx / DMA_IRQ_CHAN_NR;
> +	irq_offset = pchan->idx % DMA_IRQ_CHAN_NR;
> +
> +	irq_val = readl(sdev->base + DMA_IRQ_EN(irq_offset));
> +	irq_val |= DMA_IRQ_QUEUE << (irq_offset * DMA_IRQ_CHAN_WIDTH);
> +	writel(irq_val, sdev->base + DMA_IRQ_EN(irq_offset));
> +
> +	writel(pchan->desc->p_lli, pchan->base + DMA_CHAN_LLI_ADDR);
> +	writel(DMA_CHAN_ENABLE_START, pchan->base + DMA_CHAN_ENABLE);
> +
> +	sun6i_dma_dump_com_regs(sdev);
> +	sun6i_dma_dump_chan_regs(pchan);
> +
> +	return 0;
> +}
> +
> +static void sun6i_dma_tasklet(unsigned long data)
> +{
> +	struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)data;
> +	struct sun6i_vchan *vchan;
> +	struct sun6i_pchan *pchan;
> +	unsigned int pchan_alloc = 0;
> +	unsigned int pchan_idx;
> +
> +	list_for_each_entry(vchan, &sdev->slave.channels, vc.chan.device_node) {
> +		spin_lock_irq(&vchan->vc.lock);
> +
> +		pchan = vchan->phy;
> +
> +		if (pchan && pchan->done) {
> +			if (sun6i_dma_start_desc(vchan)) {
> +				/*
> +				 * No current txd associated with this channel
> +				 */
> +				dev_dbg(sdev->slave.dev, "pchan %u: free\n",
> +					pchan->idx);
> +
> +				/* Mark this channel free */
> +				vchan->phy = NULL;
> +				pchan->vchan = NULL;
> +			}
> +		}
> +		spin_unlock_irq(&vchan->vc.lock);
> +	}
> +
> +	spin_lock_irq(&sdev->lock);
> +	for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
> +		pchan = &sdev->pchans[pchan_idx];
> +
> +		if (pchan->vchan == NULL && !list_empty(&sdev->pending)) {
> +			vchan = list_first_entry(&sdev->pending,
> +						 struct sun6i_vchan, node);
> +
> +			/* remove from pending channels */

Keep style in the comments. Like capital letter to start sentence with.

> +			list_del_init(&vchan->node);
> +			pchan_alloc |= BIT(pchan_idx);
> +
> +			/* Mark this channel allocated */
> +			pchan->vchan = vchan;
> +			vchan->phy = pchan;
> +			dev_dbg(sdev->slave.dev, "pchan %u: alloc vchan %p\n",
> +				pchan->idx, &vchan->vc);
> +		}
> +	}
> +	spin_unlock_irq(&sdev->lock);
> +
> +	for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
> +		if (pchan_alloc & BIT(pchan_idx)) {
> +			pchan = sdev->pchans + pchan_idx;
> +			vchan = pchan->vchan;
> +			if (vchan) {
> +				spin_lock_irq(&vchan->vc.lock);
> +				sun6i_dma_start_desc(vchan);
> +				spin_unlock_irq(&vchan->vc.lock);
> +			}
> +		}
> +	}
> +}
> +
> +static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
> +{
> +	struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)dev_id;
> +	struct sun6i_vchan *vchan;
> +	struct sun6i_pchan *pchan;
> +	int i, j, ret = 0;
> +	u32 status;
> +
> +	for (i = 0; i < 2; i++) {
> +		status = readl(sdev->base + DMA_IRQ_STAT(i));
> +		if (!status) {
> +			ret |= IRQ_NONE;

Maybe move this to definition block.

> +			continue;
> +		}
> +
> +		dev_dbg(sdev->slave.dev, "DMA irq status %s: 0x%x\n",
> +			i ? "high" : "low", status);
> +
> +		writel(status, sdev->base + DMA_IRQ_STAT(i));
> +
> +		for (j = 0; (j < 8) && status; j++) {
> +			if (status & DMA_IRQ_QUEUE) {
> +				pchan = sdev->pchans + j;
> +				vchan = pchan->vchan;
> +
> +				if (vchan) {
> +					unsigned long flags;
> +
> +					spin_lock_irqsave(&vchan->vc.lock,
> +							  flags);
> +					vchan_cookie_complete(&pchan->desc->vd);
> +					pchan->done = pchan->desc;
> +					spin_unlock_irqrestore(&vchan->vc.lock,
> +							       flags);
> +				}
> +			}
> +
> +			status = status >> 4;
> +		}
> +
> +		ret |= IRQ_HANDLED;

In case one is handled, another is not, what you have to do?

> +	}
> +
> +	if (ret == IRQ_HANDLED)
> +		tasklet_schedule(&sdev->task);
> +
> +	return ret;
> +}
> +
> +static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_memcpy(
> +		struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> +		size_t len, unsigned long flags)
> +{
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
> +	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
> +	struct dma_slave_config *sconfig = &vchan->cfg;
> +	struct sun6i_dma_lli *v_lli;
> +	struct sun6i_desc *txd;
> +	dma_addr_t p_lli;
> +
> +	dev_dbg(chan2dev(chan),
> +		"%s; chan: %d, dest: 0x%08x, src: 0x%08x, len: 0x%08x. flags: 0x%08lx\n",
> +		__func__, vchan->vc.chan.chan_id, dest, src, len, flags);
> +
> +	if (!len)
> +		return NULL;
> +
> +	txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
> +	if (!txd)
> +		return NULL;
> +
> +	v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
> +	if (!v_lli) {
> +		dev_err(sdev->slave.dev, "Failed to alloc lli memory\n");
> +		kfree(txd);
> +		return NULL;
> +	}
> +
> +	sun6i_dma_cfg_lli(v_lli, src, dest, len, sconfig);
> +	v_lli->cfg |= DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
> +		DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
> +		DMA_CHAN_CFG_DST_LINEAR_MODE |
> +		DMA_CHAN_CFG_SRC_LINEAR_MODE;
> +
> +	sun6i_dma_lli_add(NULL, v_lli, p_lli, txd);
> +
> +	sun6i_dma_dump_lli(vchan, v_lli);
> +
> +	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
> +}
> +
> +static struct dma_async_tx_descriptor *sun6i_dma_prep_slave_sg(
> +		struct dma_chan *chan, struct scatterlist *sgl,
> +		unsigned int sg_len, enum dma_transfer_direction dir,
> +		unsigned long flags, void *context)
> +{
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
> +	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
> +	struct dma_slave_config *sconfig = &vchan->cfg;
> +	struct sun6i_dma_lli *v_lli, *prev = NULL;
> +	struct sun6i_desc *txd;
> +	struct scatterlist *sg;
> +	dma_addr_t p_lli;
> +	int i;
> +
> +	if (!sgl)
> +		return NULL;
> +
> +	txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
> +	if (!txd)
> +		return NULL;
> +
> +	for_each_sg(sgl, sg, sg_len, i) {
> +		v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
> +		if (!v_lli) {
> +			kfree(txd);
> +			return NULL;
> +		}
> +
> +		if (dir == DMA_MEM_TO_DEV) {
> +			sun6i_dma_cfg_lli(v_lli, sg_dma_address(sg),
> +					  sconfig->dst_addr, sg_dma_len(sg),
> +					  sconfig);
> +			v_lli->cfg |= DMA_CHAN_CFG_DST_IO_MODE |
> +				DMA_CHAN_CFG_SRC_LINEAR_MODE |
> +				DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
> +				DMA_CHAN_CFG_DST_DRQ(vchan->port);
> +
> +			dev_dbg(chan2dev(chan), "%s; chan: %d, dest: 0x%08x, "
> +				"src: 0x%08x, len: 0x%08x. flags: 0x%08lx\n",
> +				__func__, vchan->vc.chan.chan_id,
> +				sconfig->dst_addr, sg_dma_address(sg),
> +				sg_dma_len(sg), flags);
> +
> +		} else if (dir == DMA_DEV_TO_MEM) {
> +			sun6i_dma_cfg_lli(v_lli, sconfig->src_addr,
> +					  sg_dma_address(sg), sg_dma_len(sg),
> +					  sconfig);
> +			v_lli->cfg |= DMA_CHAN_CFG_DST_LINEAR_MODE |
> +				DMA_CHAN_CFG_SRC_IO_MODE |
> +				DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
> +				DMA_CHAN_CFG_SRC_DRQ(vchan->port);
> +
> +			dev_dbg(chan2dev(chan), "%s; chan: %d, dest: 0x%08x, "
> +				"src: 0x%08x, len: 0x%08x. flags: 0x%08lx\n",
> +				__func__, vchan->vc.chan.chan_id,
> +				sg_dma_address(sg), sconfig->src_addr,
> +				sg_dma_len(sg), flags);
> +		}
> +
> +		prev = sun6i_dma_lli_add(prev, v_lli, p_lli, txd);
> +	}
> +
> +#ifdef DEBUG
> +	dev_dbg(chan2dev(chan), "First: 0x%08x\n", txd->p_lli);
> +	for (prev = txd->v_lli; prev != NULL; prev = prev->v_lli_next)
> +		sun6i_dma_dump_lli(vchan, prev);
> +#endif
> +
> +	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
> +}
> +
> +static int sun6i_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> +		       unsigned long arg)
> +{
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
> +	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
> +	struct sun6i_pchan *pchan = vchan->phy;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	switch (cmd) {
> +	case DMA_RESUME:
> +		dev_dbg(chan2dev(chan), "vchan %p: resume\n", &vchan->vc);
> +
> +		spin_lock_irqsave(&vchan->vc.lock, flags);
> +
> +		if (pchan) {
> +			writel(DMA_CHAN_PAUSE_RESUME,
> +			       pchan->base + DMA_CHAN_PAUSE);
> +		} else if (!list_empty(&vchan->vc.desc_issued)) {
> +			spin_lock(&sdev->lock);
> +			list_add_tail(&vchan->node, &sdev->pending);
> +			spin_unlock(&sdev->lock);
> +		}
> +
> +		spin_unlock_irqrestore(&vchan->vc.lock, flags);
> +		break;
> +
> +	case DMA_PAUSE:
> +		dev_dbg(chan2dev(chan), "vchan %p: pause\n", &vchan->vc);
> +
> +		if (pchan) {
> +			writel(DMA_CHAN_PAUSE_PAUSE,
> +			       pchan->base + DMA_CHAN_PAUSE);
> +		} else {
> +			spin_lock(&sdev->lock);
> +			list_del_init(&vchan->node);
> +			spin_unlock(&sdev->lock);
> +		}
> +		break;
> +
> +	case DMA_TERMINATE_ALL:
> +		ret = sun6i_dma_terminate_all(vchan);
> +		break;
> +	case DMA_SLAVE_CONFIG:
> +		memcpy(&vchan->cfg, (struct dma_slave_config *)arg,
> +		       sizeof(struct dma_slave_config));
> +		break;
> +	default:
> +		ret = -ENXIO;
> +		break;
> +	}
> +	return ret;
> +}
> +
> +static enum dma_status sun6i_dma_tx_status(struct dma_chan *chan,
> +					   dma_cookie_t cookie,
> +					   struct dma_tx_state *state)
> +{
> +	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
> +	struct sun6i_pchan *pchan = vchan->phy;
> +	struct sun6i_dma_lli *lli;
> +	struct virt_dma_desc *vd;
> +	struct sun6i_desc *txd;
> +	enum dma_status ret;
> +	unsigned long flags;
> +	size_t bytes = 0;
> +
> +	ret = dma_cookie_status(chan, cookie, state);
> +	if (ret == DMA_COMPLETE)
> +		return ret;
> +
> +	spin_lock_irqsave(&vchan->vc.lock, flags);
> +
> +	vd = vchan_find_desc(&vchan->vc, cookie);
> +	txd = to_sun6i_desc(&vd->tx);
> +
> +	if (vd) {
> +		for (lli = txd->v_lli; lli != NULL; lli = lli->v_lli_next)
> +			bytes += lli->len;
> +	} else if (!pchan || !pchan->desc) {
> +		bytes = 0;
> +	} else {
> +		bytes = readl(pchan->base + DMA_CHAN_CUR_CNT);
> +	}
> +
> +	spin_unlock_irqrestore(&vchan->vc.lock, flags);
> +
> +	dma_set_residue(state, bytes);
> +
> +	return ret;
> +}
> +
> +static void sun6i_dma_issue_pending(struct dma_chan *chan)
> +{
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
> +	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&vchan->vc.lock, flags);
> +
> +	if (vchan_issue_pending(&vchan->vc)) {
> +		spin_lock(&sdev->lock);
> +
> +		if (!vchan->phy) {
> +			if (list_empty(&vchan->node)) {
> +				list_add_tail(&vchan->node, &sdev->pending);
> +				tasklet_schedule(&sdev->task);
> +				dev_dbg(chan2dev(chan), "vchan %p: issued\n",
> +					&vchan->vc);
> +			}
> +		}
> +
> +		spin_unlock(&sdev->lock);
> +	} else {
> +		dev_dbg(chan2dev(chan), "vchan %p: nothing to issue\n",
> +			&vchan->vc);
> +	}
> +
> +	spin_unlock_irqrestore(&vchan->vc.lock, flags);
> +}
> +
> +static int sun6i_dma_alloc_chan_resources(struct dma_chan *chan)
> +{
> +	return 0;
> +}
> +
> +static void sun6i_dma_free_chan_resources(struct dma_chan *chan)
> +{
> +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
> +	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&sdev->lock, flags);
> +	list_del_init(&vchan->node);
> +	spin_unlock_irqrestore(&sdev->lock, flags);
> +
> +	vchan_free_chan_resources(&vchan->vc);
> +}
> +
> +static inline void sun6i_dma_free(struct sun6i_dma_dev *sdc)
> +{
> +	int i;
> +
> +	for (i = 0; i < NR_MAX_VCHANS; i++) {
> +		struct sun6i_vchan *vchan = &sdc->vchans[i];
> +
> +		list_del(&vchan->vc.chan.device_node);
> +		tasklet_kill(&vchan->vc.task);
> +	}
> +
> +	tasklet_kill(&sdc->task);
> +}
> +
> +static struct dma_chan *sun6i_dma_of_xlate(struct of_phandle_args *dma_spec,
> +					   struct of_dma *ofdma)
> +{
> +	struct sun6i_dma_dev *sdev = ofdma->of_dma_data;
> +	struct sun6i_vchan *vchan;
> +	struct dma_chan *chan;
> +	u8 port = dma_spec->args[0];
> +
> +	if (port > NR_MAX_REQUESTS)
> +		return NULL;
> +
> +	chan = dma_get_any_slave_channel(&sdev->slave);
> +	if (!chan)
> +		return NULL;
> +
> +	vchan = to_sun6i_vchan(chan);
> +	vchan->port = port;
> +
> +	return chan;
> +}
> +
> +static int sun6i_dma_probe(struct platform_device *pdev)
> +{
> +	struct sun6i_dma_dev *sdc;
> +	struct resource *res;
> +	int irq;
> +	int ret, i;
> +
> +	sdc = devm_kzalloc(&pdev->dev, sizeof(*sdc), GFP_KERNEL);
> +	if (!sdc)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	sdc->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(sdc->base))
> +		return PTR_ERR(sdc->base);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	ret = devm_request_irq(&pdev->dev, irq, sun6i_dma_interrupt, 0,
> +			       dev_name(&pdev->dev), sdc);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Cannot request IRQ\n");
> +		return ret;
> +	}
> +
> +	sdc->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(sdc->clk)) {
> +		dev_err(&pdev->dev, "No clock specified\n");
> +		return PTR_ERR(sdc->clk);
> +	}
> +
> +	sdc->rstc = devm_reset_control_get(&pdev->dev, NULL);
> +	if (IS_ERR(sdc->rstc)) {
> +		dev_err(&pdev->dev, "No reset controller specified\n");
> +		return PTR_ERR(sdc->rstc);
> +	}
> +
> +	sdc->pool = dma_pool_create(dev_name(&pdev->dev), &pdev->dev,
> +					sizeof(struct sun6i_dma_lli), 4, 0);

dmam_pool_create()

> +	if (!sdc->pool) {
> +		dev_err(&pdev->dev, "No memory for descriptors dma pool\n");
> +		return -ENOMEM;
> +	}
> +
> +	platform_set_drvdata(pdev, sdc);
> +	INIT_LIST_HEAD(&sdc->pending);
> +	spin_lock_init(&sdc->lock);
> +
> +	dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask);
> +	dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask);
> +	dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask);
> +
> +	INIT_LIST_HEAD(&sdc->slave.channels);
> +	sdc->slave.device_alloc_chan_resources	= sun6i_dma_alloc_chan_resources;
> +	sdc->slave.device_free_chan_resources	= sun6i_dma_free_chan_resources;
> +	sdc->slave.device_tx_status		= sun6i_dma_tx_status;
> +	sdc->slave.device_issue_pending		= sun6i_dma_issue_pending;
> +	sdc->slave.device_prep_slave_sg		= sun6i_dma_prep_slave_sg;
> +	sdc->slave.device_prep_dma_memcpy	= sun6i_dma_prep_dma_memcpy;
> +	sdc->slave.device_control		= sun6i_dma_control;
> +	sdc->slave.chancnt			= NR_MAX_VCHANS;
> +
> +	sdc->slave.dev = &pdev->dev;
> +
> +	sdc->pchans = devm_kzalloc(&pdev->dev,
> +				   NR_MAX_CHANNELS * sizeof(struct sun6i_pchan),
> +				   GFP_KERNEL);
> +	if (!sdc->pchans) {
> +		ret = -ENOMEM;
> +		goto err_dma_pool_destroy;
> +	}
> +
> +	sdc->vchans = devm_kzalloc(&pdev->dev,
> +				   NR_MAX_VCHANS * sizeof(struct sun6i_vchan),
> +				   GFP_KERNEL);
> +	if (!sdc->vchans) {
> +		ret = -ENOMEM;
> +		goto err_dma_pool_destroy;
> +	}
> +
> +	tasklet_init(&sdc->task, sun6i_dma_tasklet, (unsigned long)sdc);
> +
> +	for (i = 0; i < NR_MAX_CHANNELS; i++) {
> +		struct sun6i_pchan *pchan = &sdc->pchans[i];
> +
> +		pchan->idx = i;
> +		pchan->base = sdc->base + 0x100 + i * 0x40;
> +	}
> +
> +	for (i = 0; i < NR_MAX_VCHANS; i++) {
> +		struct sun6i_vchan *vchan = &sdc->vchans[i];
> +
> +		INIT_LIST_HEAD(&vchan->node);
> +		vchan->vc.desc_free = sun6i_dma_free_desc;
> +		vchan_init(&vchan->vc, &sdc->slave);
> +	}
> +
> +	reset_control_deassert(sdc->rstc);
> +
> +	clk_prepare_enable(sdc->clk);

Would you like to check an return code here?

> +
> +	ret = dma_async_device_register(&sdc->slave);
> +	if (ret) {
> +		dev_warn(&pdev->dev, "Failed to register DMA engine device\n");
> +		goto err_clk_disable;
> +	}
> +
> +	ret = of_dma_controller_register(pdev->dev.of_node, sun6i_dma_of_xlate,
> +					 sdc);
> +	if (ret) {
> +		dev_err(&pdev->dev, "of_dma_controller_register failed\n");
> +		goto err_dma_unregister;
> +	}
> +
> +	return 0;
> +
> +err_dma_unregister:
> +	dma_async_device_unregister(&sdc->slave);
> +err_clk_disable:
> +	clk_disable_unprepare(sdc->clk);
> +	reset_control_assert(sdc->rstc);
> +	sun6i_dma_free(sdc);
> +err_dma_pool_destroy:
> +	dma_pool_destroy(sdc->pool);
> +	return ret;
> +}
> +
> +static int sun6i_dma_remove(struct platform_device *pdev)
> +{
> +	struct sun6i_dma_dev *sdc = platform_get_drvdata(pdev);
> +
> +	of_dma_controller_free(pdev->dev.of_node);
> +	dma_async_device_unregister(&sdc->slave);
> +
> +	clk_disable_unprepare(sdc->clk);
> +	reset_control_assert(sdc->rstc);
> +
> +	sun6i_dma_free(sdc);
> +
> +	dma_pool_destroy(sdc->pool);
> +
> +	return 0;
> +}
> +
> +static struct of_device_id sun6i_dma_match[] = {
> +	{ .compatible = "allwinner,sun6i-a31-dma" }
> +};
> +
> +static struct platform_driver sun6i_dma_driver = {
> +	.probe		= sun6i_dma_probe,
> +	.remove		= sun6i_dma_remove,
> +	.driver = {
> +		.name		= "sun6i-dma",
> +		.of_match_table	= sun6i_dma_match,
> +	},
> +};
> +module_platform_driver(sun6i_dma_driver);
> +
> +MODULE_DESCRIPTION("Allwinner A31 DMA Controller Driver");
> +MODULE_AUTHOR("Sugar <[e-mail]>");
> +MODULE_AUTHOR("Maxime Ripard <[e-mail]>");
> +MODULE_LICENSE("GPL");

Maxime Ripard Feb. 28, 2014, 10:36 a.m. UTC | #2

Hi Andy,

On Tue, Feb 25, 2014 at 01:28:15PM +0200, Andy Shevchenko wrote:
> > +static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
> > +{
> > +	struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)dev_id;
> > +	struct sun6i_vchan *vchan;
> > +	struct sun6i_pchan *pchan;
> > +	int i, j, ret = 0;
> > +	u32 status;
> > +
> > +	for (i = 0; i < 2; i++) {
> > +		status = readl(sdev->base + DMA_IRQ_STAT(i));
> > +		if (!status) {
> > +			ret |= IRQ_NONE;
> 
> Maybe move this to definition block.
> 
> > +			continue;
> > +		}
> > +
> > +		dev_dbg(sdev->slave.dev, "DMA irq status %s: 0x%x\n",
> > +			i ? "high" : "low", status);
> > +
> > +		writel(status, sdev->base + DMA_IRQ_STAT(i));
> > +
> > +		for (j = 0; (j < 8) && status; j++) {
> > +			if (status & DMA_IRQ_QUEUE) {
> > +				pchan = sdev->pchans + j;
> > +				vchan = pchan->vchan;
> > +
> > +				if (vchan) {
> > +					unsigned long flags;
> > +
> > +					spin_lock_irqsave(&vchan->vc.lock,
> > +							  flags);
> > +					vchan_cookie_complete(&pchan->desc->vd);
> > +					pchan->done = pchan->desc;
> > +					spin_unlock_irqrestore(&vchan->vc.lock,
> > +							       flags);
> > +				}
> > +			}
> > +
> > +			status = status >> 4;
> > +		}
> > +
> > +		ret |= IRQ_HANDLED;
> 
> In case one is handled, another is not, what you have to do?

The interrupt status is split across two registers. In the case where
one of the two register reports an interrupt, we still have to handle
our interrupt, we actually did, so we have to return IRQ_HANDLED.

[ ... ]

> > +static int sun6i_dma_probe(struct platform_device *pdev)
> > +{
> > +	struct sun6i_dma_dev *sdc;
> > +	struct resource *res;
> > +	int irq;
> > +	int ret, i;
> > +
> > +	sdc = devm_kzalloc(&pdev->dev, sizeof(*sdc), GFP_KERNEL);
> > +	if (!sdc)
> > +		return -ENOMEM;
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	sdc->base = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(sdc->base))
> > +		return PTR_ERR(sdc->base);
> > +
> > +	irq = platform_get_irq(pdev, 0);
> > +	ret = devm_request_irq(&pdev->dev, irq, sun6i_dma_interrupt, 0,
> > +			       dev_name(&pdev->dev), sdc);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Cannot request IRQ\n");
> > +		return ret;
> > +	}
> > +
> > +	sdc->clk = devm_clk_get(&pdev->dev, NULL);
> > +	if (IS_ERR(sdc->clk)) {
> > +		dev_err(&pdev->dev, "No clock specified\n");
> > +		return PTR_ERR(sdc->clk);
> > +	}
> > +
> > +	sdc->rstc = devm_reset_control_get(&pdev->dev, NULL);
> > +	if (IS_ERR(sdc->rstc)) {
> > +		dev_err(&pdev->dev, "No reset controller specified\n");
> > +		return PTR_ERR(sdc->rstc);
> > +	}
> > +
> > +	sdc->pool = dma_pool_create(dev_name(&pdev->dev), &pdev->dev,
> > +					sizeof(struct sun6i_dma_lli), 4, 0);
> 
> dmam_pool_create()

Aaah. I looked for a devm_dma_pool_create, but I missed this one.

> 
> > +	if (!sdc->pool) {
> > +		dev_err(&pdev->dev, "No memory for descriptors dma pool\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, sdc);
> > +	INIT_LIST_HEAD(&sdc->pending);
> > +	spin_lock_init(&sdc->lock);
> > +
> > +	dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask);
> > +	dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask);
> > +	dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask);
> > +
> > +	INIT_LIST_HEAD(&sdc->slave.channels);
> > +	sdc->slave.device_alloc_chan_resources	= sun6i_dma_alloc_chan_resources;
> > +	sdc->slave.device_free_chan_resources	= sun6i_dma_free_chan_resources;
> > +	sdc->slave.device_tx_status		= sun6i_dma_tx_status;
> > +	sdc->slave.device_issue_pending		= sun6i_dma_issue_pending;
> > +	sdc->slave.device_prep_slave_sg		= sun6i_dma_prep_slave_sg;
> > +	sdc->slave.device_prep_dma_memcpy	= sun6i_dma_prep_dma_memcpy;
> > +	sdc->slave.device_control		= sun6i_dma_control;
> > +	sdc->slave.chancnt			= NR_MAX_VCHANS;
> > +
> > +	sdc->slave.dev = &pdev->dev;
> > +
> > +	sdc->pchans = devm_kzalloc(&pdev->dev,
> > +				   NR_MAX_CHANNELS * sizeof(struct sun6i_pchan),
> > +				   GFP_KERNEL);
> > +	if (!sdc->pchans) {
> > +		ret = -ENOMEM;
> > +		goto err_dma_pool_destroy;
> > +	}
> > +
> > +	sdc->vchans = devm_kzalloc(&pdev->dev,
> > +				   NR_MAX_VCHANS * sizeof(struct sun6i_vchan),
> > +				   GFP_KERNEL);
> > +	if (!sdc->vchans) {
> > +		ret = -ENOMEM;
> > +		goto err_dma_pool_destroy;
> > +	}
> > +
> > +	tasklet_init(&sdc->task, sun6i_dma_tasklet, (unsigned long)sdc);
> > +
> > +	for (i = 0; i < NR_MAX_CHANNELS; i++) {
> > +		struct sun6i_pchan *pchan = &sdc->pchans[i];
> > +
> > +		pchan->idx = i;
> > +		pchan->base = sdc->base + 0x100 + i * 0x40;
> > +	}
> > +
> > +	for (i = 0; i < NR_MAX_VCHANS; i++) {
> > +		struct sun6i_vchan *vchan = &sdc->vchans[i];
> > +
> > +		INIT_LIST_HEAD(&vchan->node);
> > +		vchan->vc.desc_free = sun6i_dma_free_desc;
> > +		vchan_init(&vchan->vc, &sdc->slave);
> > +	}
> > +
> > +	reset_control_deassert(sdc->rstc);
> > +
> > +	clk_prepare_enable(sdc->clk);
> 
> Would you like to check an return code here?

Yep, right.

Thanks!
Maxime

Andy Shevchenko Feb. 28, 2014, 1:33 p.m. UTC | #3

On Fri, 2014-02-28 at 11:36 +0100, Maxime Ripard wrote:
> Hi Andy,
> 
> On Tue, Feb 25, 2014 at 01:28:15PM +0200, Andy Shevchenko wrote:
> > > +static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
> > > +{
> > > +	struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)dev_id;
> > > +	struct sun6i_vchan *vchan;
> > > +	struct sun6i_pchan *pchan;
> > > +	int i, j, ret = 0;
> > > +	u32 status;
> > > +
> > > +	for (i = 0; i < 2; i++) {
> > > +		status = readl(sdev->base + DMA_IRQ_STAT(i));
> > > +		if (!status) {
> > > +			ret |= IRQ_NONE;
> > 
> > Maybe move this to definition block.
> > 
> > > +			continue;
> > > +		}
> > > +
> > > +		dev_dbg(sdev->slave.dev, "DMA irq status %s: 0x%x\n",
> > > +			i ? "high" : "low", status);
> > > +
> > > +		writel(status, sdev->base + DMA_IRQ_STAT(i));
> > > +
> > > +		for (j = 0; (j < 8) && status; j++) {
> > > +			if (status & DMA_IRQ_QUEUE) {
> > > +				pchan = sdev->pchans + j;
> > > +				vchan = pchan->vchan;
> > > +
> > > +				if (vchan) {
> > > +					unsigned long flags;
> > > +
> > > +					spin_lock_irqsave(&vchan->vc.lock,
> > > +							  flags);
> > > +					vchan_cookie_complete(&pchan->desc->vd);
> > > +					pchan->done = pchan->desc;
> > > +					spin_unlock_irqrestore(&vchan->vc.lock,
> > > +							       flags);
> > > +				}
> > > +			}
> > > +
> > > +			status = status >> 4;
> > > +		}
> > > +
> > > +		ret |= IRQ_HANDLED;
> > 
> > In case one is handled, another is not, what you have to do?
> 
> The interrupt status is split across two registers. In the case where
> one of the two register reports an interrupt, we still have to handle
> our interrupt, we actually did, so we have to return IRQ_HANDLED.

You removed the code below this assignment, but if I remember correctly
you check for exact value there.

In case of one is not handled and the other is handled you will have ret
= IRQ_HANDLED | IRQ_NONE. Thus, your following code will not be
executed. Is it by design?

Maxime Ripard Feb. 28, 2014, 2:27 p.m. UTC | #4

On Fri, Feb 28, 2014 at 03:33:11PM +0200, Andy Shevchenko wrote:
> On Fri, 2014-02-28 at 11:36 +0100, Maxime Ripard wrote:
> > Hi Andy,
> > 
> > On Tue, Feb 25, 2014 at 01:28:15PM +0200, Andy Shevchenko wrote:
> > > > +static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
> > > > +{
> > > > +	struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)dev_id;
> > > > +	struct sun6i_vchan *vchan;
> > > > +	struct sun6i_pchan *pchan;
> > > > +	int i, j, ret = 0;
> > > > +	u32 status;
> > > > +
> > > > +	for (i = 0; i < 2; i++) {
> > > > +		status = readl(sdev->base + DMA_IRQ_STAT(i));
> > > > +		if (!status) {
> > > > +			ret |= IRQ_NONE;
> > > 
> > > Maybe move this to definition block.
> > > 
> > > > +			continue;
> > > > +		}
> > > > +
> > > > +		dev_dbg(sdev->slave.dev, "DMA irq status %s: 0x%x\n",
> > > > +			i ? "high" : "low", status);
> > > > +
> > > > +		writel(status, sdev->base + DMA_IRQ_STAT(i));
> > > > +
> > > > +		for (j = 0; (j < 8) && status; j++) {
> > > > +			if (status & DMA_IRQ_QUEUE) {
> > > > +				pchan = sdev->pchans + j;
> > > > +				vchan = pchan->vchan;
> > > > +
> > > > +				if (vchan) {
> > > > +					unsigned long flags;
> > > > +
> > > > +					spin_lock_irqsave(&vchan->vc.lock,
> > > > +							  flags);
> > > > +					vchan_cookie_complete(&pchan->desc->vd);
> > > > +					pchan->done = pchan->desc;
> > > > +					spin_unlock_irqrestore(&vchan->vc.lock,
> > > > +							       flags);
> > > > +				}
> > > > +			}
> > > > +
> > > > +			status = status >> 4;
> > > > +		}
> > > > +
> > > > +		ret |= IRQ_HANDLED;
> > > 
> > > In case one is handled, another is not, what you have to do?
> > 
> > The interrupt status is split across two registers. In the case where
> > one of the two register reports an interrupt, we still have to handle
> > our interrupt, we actually did, so we have to return IRQ_HANDLED.
> 
> You removed the code below this assignment, but if I remember correctly
> you check for exact value there.
> 
> In case of one is not handled and the other is handled you will have ret
> = IRQ_HANDLED | IRQ_NONE. Thus, your following code will not be
> executed. Is it by design?

The code that got removed was

if (ret == IRQ_HANDLED)
   tasklet_schedule()

return ret;

The only thing that wouldn't have been executed if we had no
interrupts to report was the tasklet_schedule.

This has lightly changed though in the v2, thanks to your comments.

I don't have the | anymore, and call tasklet_schedule directly in the
loop.

I'll send the v2 in a short while.

Maxime

Patch

diff --git a/Documentation/devicetree/bindings/dma/sun6i-dma.txt b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
new file mode 100644
index 0000000..5d7c86d
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
@@ -0,0 +1,45 @@ 
+Allwinner A31 DMA Controller
+
+This driver follows the generic DMA bindings defined in dma.txt.
+
+Required properties:
+
+- compatible:	Must be "allwinner,sun6i-a31-dma"
+- reg:		Should contain the registers base address and length
+- interrupts:	Should contain a reference to the interrupt used by this device
+- clocks:	Should contain a reference to the parent AHB clock
+- resets:	Should contain a reference to the reset controller asserting
+	  	this device in reset
+- #dma-cells :	Should be 1, a single cell holding a line request number
+
+Example:
+	dma: dma-controller@01c02000 {
+		compatible = "allwinner,sun6i-a31-dma";
+		reg = <0x01c02000 0x1000>;
+		interrupts = <0 50 4>;
+		clocks = <&ahb1_gates 6>;
+		resets = <&ahb1_rst 6>;
+		#dma-cells = <1>;
+	};
+
+Clients:
+
+DMA clients connected to the A31 DMA controller must use the format
+described in the dma.txt file, using a two-cell specifier for each
+channel: a phandle plus one integer cells.
+The two cells in order are:
+
+1. A phandle pointing to the DMA controller.
+2. The port ID as specified in the datasheet
+
+Example:
+spi2: spi@01c6a000 {
+	compatible = "allwinner,sun6i-a31-spi";
+	reg = <0x01c6a000 0x1000>;
+	interrupts = <0 67 4>;
+	clocks = <&ahb1_gates 22>, <&spi2_clk>;
+	clock-names = "ahb", "mod";
+	dmas = <&dma 25>, <&dma 25>;
+	dma-names = "rx", "tx";
+	resets = <&ahb1_rst 22>;
+};
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 605b016..7923697 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -351,6 +351,14 @@  config MOXART_DMA
 	help
 	  Enable support for the MOXA ART SoC DMA controller.
 
+config DMA_SUN6I
+	tristate "Allwinner A31 SoCs DMA support"
+	depends on ARCH_SUNXI
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Support for the DMA engine for Allwinner A31 SoCs.
+
 config DMA_ENGINE
 	bool
 
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index a029d0f4..18cdbad 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -44,3 +44,4 @@  obj-$(CONFIG_DMA_JZ4740) += dma-jz4740.o
 obj-$(CONFIG_TI_CPPI41) += cppi41.o
 obj-$(CONFIG_K3_DMA) += k3dma.o
 obj-$(CONFIG_MOXART_DMA) += moxart-dma.o
+obj-$(CONFIG_DMA_SUN6I) += sun6i-dma.o
diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
new file mode 100644
index 0000000..2649fde
--- /dev/null
+++ b/drivers/dma/sun6i-dma.c
@@ -0,0 +1,960 @@ 
+/*
+ * Copyright (C) 2013-2014 Allwinner Tech Co., Ltd
+ * Author: Sugar <[e-mail]>
+ *
+ * Copyright (C) 2014 Maxime Ripard
+ * Maxime Ripard <[e-mail]>
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "virt-dma.h"
+
+/*
+ * There's 16 physical channels that can work in parallel.
+ *
+ * However we have 30 different endpoints for our requests.
+ *
+ * Since the channels are able to handle only an unidirectional
+ * transfer, we need to allocate more virtual channels so that
+ * everyone can grab one channel.
+ *
+ * Some devices can't work in both direction (mostly because it
+ * wouldn't make sense), so we have a bit fewer virtual channels than
+ * 2 channels per endpoints.
+ */
+
+#define NR_MAX_CHANNELS		16
+#define NR_MAX_REQUESTS		30
+#define NR_MAX_VCHANS		53
+
+/*
+ * Common registers
+ */
+#define DMA_IRQ_EN(x)		((x) * 0x04)
+#define DMA_IRQ_HALF			BIT(0)
+#define DMA_IRQ_PKG			BIT(1)
+#define DMA_IRQ_QUEUE			BIT(2)
+
+#define DMA_IRQ_CHAN_NR			8
+#define DMA_IRQ_CHAN_WIDTH		4
+
+
+#define DMA_IRQ_STAT(x)		((x) * 0x04 + 0x10)
+
+#define DMA_STAT		0x30
+
+/*
+ * Channels specific registers
+ */
+#define DMA_CHAN_ENABLE		0x00
+#define DMA_CHAN_ENABLE_START		BIT(0)
+#define DMA_CHAN_ENABLE_STOP		0
+
+#define DMA_CHAN_PAUSE		0x04
+#define DMA_CHAN_PAUSE_PAUSE		BIT(1)
+#define DMA_CHAN_PAUSE_RESUME		0
+
+#define DMA_CHAN_LLI_ADDR	0x08
+
+#define DMA_CHAN_CUR_CFG	0x0c
+#define DMA_CHAN_CFG_SRC_DRQ(x)		((x) & 0x1f)
+#define DMA_CHAN_CFG_SRC_IO_MODE	BIT(5)
+#define DMA_CHAN_CFG_SRC_LINEAR_MODE	(0 << 5)
+#define DMA_CHAN_CFG_SRC_BURST(x)	(((x) & 0x3) << 7)
+#define DMA_CHAN_CFG_SRC_WIDTH(x)	(((x) & 0x3) << 9)
+
+#define DMA_CHAN_CFG_DST_DRQ(x)		(DMA_CHAN_CFG_SRC_DRQ(x) << 16)
+#define DMA_CHAN_CFG_DST_IO_MODE	(DMA_CHAN_CFG_SRC_IO_MODE << 16)
+#define DMA_CHAN_CFG_DST_LINEAR_MODE	(DMA_CHAN_CFG_SRC_LINEAR_MODE << 16)
+#define DMA_CHAN_CFG_DST_BURST(x)	(DMA_CHAN_CFG_SRC_BURST(x) << 16)
+#define DMA_CHAN_CFG_DST_WIDTH(x)	(DMA_CHAN_CFG_SRC_WIDTH(x) << 16)
+
+#define DMA_CHAN_CUR_SRC	0x10
+
+#define DMA_CHAN_CUR_DST	0x14
+
+#define DMA_CHAN_CUR_CNT	0x18
+
+#define DMA_CHAN_CUR_PARA	0x1c
+
+
+/*
+ * Various hardware related defines
+ */
+#define LLI_LAST_ITEM	0xfffff800
+#define NORMAL_WAIT	8
+#define DRQ_SDRAM	1
+
+/*
+ * Hardware representation of the LLI
+ *
+ * The hardware will be fed the physical address of this structure,
+ * and read its content in order to start the transfer.
+ */
+struct sun6i_dma_lli {
+	u32			cfg;
+	dma_addr_t		src;
+	dma_addr_t		dst;
+	u32			len;
+	u32			para;
+	dma_addr_t		p_lli_next;
+	struct sun6i_dma_lli	*v_lli_next;
+} __packed;
+
+
+struct sun6i_desc {
+	struct virt_dma_desc	vd;
+	dma_addr_t		p_lli;
+	struct sun6i_dma_lli	*v_lli;
+};
+
+struct sun6i_pchan {
+	u32			idx;
+	void __iomem		*base;
+	struct sun6i_vchan	*vchan;
+	struct sun6i_desc	*desc;
+	struct sun6i_desc	*done;
+};
+
+struct sun6i_vchan {
+	struct virt_dma_chan	vc;
+	struct list_head	node;
+	struct dma_slave_config	cfg;
+	struct sun6i_pchan	*phy;
+	u8			port;
+};
+
+struct sun6i_dma_dev {
+	struct dma_device	slave;
+	void __iomem		*base;
+	struct clk		*clk;
+	struct reset_control	*rstc;
+	spinlock_t		lock;
+	struct tasklet_struct	task;
+	struct list_head	pending;
+	struct dma_pool		*pool;
+	struct sun6i_pchan	*pchans;
+	struct sun6i_vchan	*vchans;
+};
+
+static struct device *chan2dev(struct dma_chan *chan)
+{
+	return &chan->dev->device;
+}
+
+static inline struct sun6i_dma_dev *to_sun6i_dma_dev(struct dma_device *d)
+{
+	return container_of(d, struct sun6i_dma_dev, slave);
+}
+
+static inline struct sun6i_vchan *to_sun6i_vchan(struct dma_chan *chan)
+{
+	return container_of(chan, struct sun6i_vchan, vc.chan);
+}
+
+static inline struct sun6i_desc *
+to_sun6i_desc(struct dma_async_tx_descriptor *tx)
+{
+	return container_of(tx, struct sun6i_desc, vd.tx);
+}
+
+static inline void sun6i_dma_dump_com_regs(struct sun6i_dma_dev *sdev)
+{
+	pr_debug("Common register:\n"
+		 "\tmask0(%04x): 0x%08x\n"
+		 "\tmask1(%04x): 0x%08x\n"
+		 "\tpend0(%04x): 0x%08x\n"
+		 "\tpend1(%04x): 0x%08x\n"
+		 "\tstats(%04x): 0x%08x\n",
+		 DMA_IRQ_EN(0), readl(sdev->base + DMA_IRQ_EN(0)),
+		 DMA_IRQ_EN(1), readl(sdev->base + DMA_IRQ_EN(1)),
+		 DMA_IRQ_STAT(0), readl(sdev->base + DMA_IRQ_STAT(0)),
+		 DMA_IRQ_STAT(1), readl(sdev->base + DMA_IRQ_STAT(1)),
+		 DMA_STAT, readl(sdev->base + DMA_STAT));
+}
+
+static inline void sun6i_dma_dump_chan_regs(struct sun6i_pchan *pchan)
+{
+	pr_debug("Chan %d reg: 0x%x\n"
+		 "\t___en(%04x): \t0x%08x\n"
+		 "\tpause(%04x): \t0x%08x\n"
+		 "\tstart(%04x): \t0x%08x\n"
+		 "\t__cfg(%04x): \t0x%08x\n"
+		 "\t__src(%04x): \t0x%08x\n"
+		 "\t__dst(%04x): \t0x%08x\n"
+		 "\tcount(%04x): \t0x%08x\n"
+		 "\t_para(%04x): \t0x%08x\n\n",
+		 pchan->idx, __virt_to_phys((unsigned long)pchan->base),
+		 DMA_CHAN_ENABLE,
+		 readl(pchan->base + DMA_CHAN_ENABLE),
+		 DMA_CHAN_PAUSE,
+		 readl(pchan->base + DMA_CHAN_PAUSE),
+		 DMA_CHAN_LLI_ADDR,
+		 readl(pchan->base + DMA_CHAN_LLI_ADDR),
+		 DMA_CHAN_CUR_CFG,
+		 readl(pchan->base + DMA_CHAN_CUR_CFG),
+		 DMA_CHAN_CUR_SRC,
+		 readl(pchan->base + DMA_CHAN_CUR_SRC),
+		 DMA_CHAN_CUR_DST,
+		 readl(pchan->base + DMA_CHAN_CUR_DST),
+		 DMA_CHAN_CUR_CNT,
+		 readl(pchan->base + DMA_CHAN_CUR_CNT),
+		 DMA_CHAN_CUR_PARA,
+		 readl(pchan->base + DMA_CHAN_CUR_PARA));
+}
+
+static inline u8 convert_burst(u8 maxburst)
+{
+	if (maxburst == 1 || maxburst > 16)
+		return 0;
+
+	return ilog2(maxburst) - 1;
+}
+
+static inline u8 convert_buswidth(enum dma_slave_buswidth addr_width)
+{
+	switch (addr_width) {
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+		return 1;
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+		return 2;
+	default:
+		return 0;
+	}
+}
+
+static void *sun6i_dma_lli_add(struct sun6i_dma_lli *prev,
+			       struct sun6i_dma_lli *next,
+			       dma_addr_t next_phy,
+			       struct sun6i_desc *txd)
+{
+	if ((!prev && !txd) || !next)
+		return NULL;
+
+	if (!prev) {
+		txd->p_lli = next_phy;
+		txd->v_lli = next;
+	} else {
+		prev->p_lli_next = next_phy;
+		prev->v_lli_next = next;
+	}
+
+	next->p_lli_next = LLI_LAST_ITEM;
+	next->v_lli_next = NULL;
+
+	return next;
+}
+
+static inline void sun6i_dma_cfg_lli(struct sun6i_dma_lli *lli,
+				     dma_addr_t src,
+				     dma_addr_t dst, u32 len,
+				     struct dma_slave_config *config)
+{
+	u32 src_width, dst_width, src_burst, dst_burst;
+
+	if (!config)
+		return;
+
+	src_burst = convert_burst(config->src_maxburst);
+	dst_burst = convert_burst(config->dst_maxburst);
+
+	src_width = convert_buswidth(config->src_addr_width);
+	dst_width = convert_buswidth(config->dst_addr_width);
+
+	lli->cfg = DMA_CHAN_CFG_SRC_BURST(src_burst) |
+		DMA_CHAN_CFG_SRC_WIDTH(src_width) |
+		DMA_CHAN_CFG_DST_BURST(dst_burst) |
+		DMA_CHAN_CFG_DST_WIDTH(dst_width);
+
+	lli->src = src;
+	lli->dst = dst;
+	lli->len = len;
+	lli->para = NORMAL_WAIT;
+
+}
+
+static inline void sun6i_dma_dump_lli(struct sun6i_vchan *vchan,
+				      struct sun6i_dma_lli *lli)
+{
+	dev_dbg(chan2dev(&vchan->vc.chan),
+		"\n\tdesc:   p - 0x%08x v - 0x%08x\n"
+		"\t\tc - 0x%08x s - 0x%08x d - 0x%08x\n"
+		"\t\tl - 0x%08x p - 0x%08x n - 0x%08x\n",
+		__virt_to_phys((unsigned long)lli), (u32)lli,
+		lli->cfg, lli->src, lli->dst,
+		lli->len, lli->para, lli->p_lli_next);
+}
+
+static void sun6i_dma_free_desc(struct virt_dma_desc *vd)
+{
+	struct sun6i_desc *txd = to_sun6i_desc(&vd->tx);
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vd->tx.chan->device);
+	struct sun6i_dma_lli *v_lli, *v_next;
+	dma_addr_t p_lli, p_next;
+
+	if (unlikely(!txd))
+		return;
+
+	p_lli = txd->p_lli;
+	v_lli = txd->v_lli;
+
+	while (v_lli) {
+		v_next = v_lli->v_lli_next;
+		p_next = v_lli->p_lli_next;
+
+		dma_pool_free(sdev->pool, v_lli, p_lli);
+
+		v_lli = v_next;
+		p_lli = p_next;
+	}
+
+	kfree(txd);
+}
+
+static int sun6i_dma_terminate_all(struct sun6i_vchan *vchan)
+{
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
+	struct sun6i_pchan *pchan = vchan->phy;
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock(&sdev->lock);
+	list_del_init(&vchan->node);
+	spin_unlock(&sdev->lock);
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+
+	vchan_get_all_descriptors(&vchan->vc, &head);
+
+	if (pchan) {
+		writel(DMA_CHAN_ENABLE_STOP, pchan->base + DMA_CHAN_ENABLE);
+		writel(DMA_CHAN_PAUSE_RESUME, pchan->base + DMA_CHAN_PAUSE);
+
+		vchan->phy = NULL;
+		pchan->vchan = NULL;
+		pchan->desc = NULL;
+		pchan->done = NULL;
+	}
+
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+	vchan_dma_desc_free_list(&vchan->vc, &head);
+
+	return 0;
+}
+
+static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
+{
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
+	struct virt_dma_desc *desc = vchan_next_desc(&vchan->vc);
+	struct sun6i_pchan *pchan = vchan->phy;
+	u32 irq_val, irq_reg, irq_offset;
+
+	if (!pchan)
+		return -EAGAIN;
+
+	if (!desc) {
+		pchan->desc = NULL;
+		pchan->done = NULL;
+		return -EAGAIN;
+	}
+
+	list_del(&desc->node);
+
+	pchan->desc = to_sun6i_desc(&desc->tx);
+	pchan->done = NULL;
+
+	sun6i_dma_dump_lli(vchan, pchan->desc->v_lli);
+
+	irq_reg = pchan->idx / DMA_IRQ_CHAN_NR;
+	irq_offset = pchan->idx % DMA_IRQ_CHAN_NR;
+
+	irq_val = readl(sdev->base + DMA_IRQ_EN(irq_offset));
+	irq_val |= DMA_IRQ_QUEUE << (irq_offset * DMA_IRQ_CHAN_WIDTH);
+	writel(irq_val, sdev->base + DMA_IRQ_EN(irq_offset));
+
+	writel(pchan->desc->p_lli, pchan->base + DMA_CHAN_LLI_ADDR);
+	writel(DMA_CHAN_ENABLE_START, pchan->base + DMA_CHAN_ENABLE);
+
+	sun6i_dma_dump_com_regs(sdev);
+	sun6i_dma_dump_chan_regs(pchan);
+
+	return 0;
+}
+
+static void sun6i_dma_tasklet(unsigned long data)
+{
+	struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)data;
+	struct sun6i_vchan *vchan;
+	struct sun6i_pchan *pchan;
+	unsigned int pchan_alloc = 0;
+	unsigned int pchan_idx;
+
+	list_for_each_entry(vchan, &sdev->slave.channels, vc.chan.device_node) {
+		spin_lock_irq(&vchan->vc.lock);
+
+		pchan = vchan->phy;
+
+		if (pchan && pchan->done) {
+			if (sun6i_dma_start_desc(vchan)) {
+				/*
+				 * No current txd associated with this channel
+				 */
+				dev_dbg(sdev->slave.dev, "pchan %u: free\n",
+					pchan->idx);
+
+				/* Mark this channel free */
+				vchan->phy = NULL;
+				pchan->vchan = NULL;
+			}
+		}
+		spin_unlock_irq(&vchan->vc.lock);
+	}
+
+	spin_lock_irq(&sdev->lock);
+	for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
+		pchan = &sdev->pchans[pchan_idx];
+
+		if (pchan->vchan == NULL && !list_empty(&sdev->pending)) {
+			vchan = list_first_entry(&sdev->pending,
+						 struct sun6i_vchan, node);
+
+			/* remove from pending channels */
+			list_del_init(&vchan->node);
+			pchan_alloc |= BIT(pchan_idx);
+
+			/* Mark this channel allocated */
+			pchan->vchan = vchan;
+			vchan->phy = pchan;
+			dev_dbg(sdev->slave.dev, "pchan %u: alloc vchan %p\n",
+				pchan->idx, &vchan->vc);
+		}
+	}
+	spin_unlock_irq(&sdev->lock);
+
+	for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
+		if (pchan_alloc & BIT(pchan_idx)) {
+			pchan = sdev->pchans + pchan_idx;
+			vchan = pchan->vchan;
+			if (vchan) {
+				spin_lock_irq(&vchan->vc.lock);
+				sun6i_dma_start_desc(vchan);
+				spin_unlock_irq(&vchan->vc.lock);
+			}
+		}
+	}
+}
+
+static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
+{
+	struct sun6i_dma_dev *sdev = (struct sun6i_dma_dev *)dev_id;
+	struct sun6i_vchan *vchan;
+	struct sun6i_pchan *pchan;
+	int i, j, ret = 0;
+	u32 status;
+
+	for (i = 0; i < 2; i++) {
+		status = readl(sdev->base + DMA_IRQ_STAT(i));
+		if (!status) {
+			ret |= IRQ_NONE;
+			continue;
+		}
+
+		dev_dbg(sdev->slave.dev, "DMA irq status %s: 0x%x\n",
+			i ? "high" : "low", status);
+
+		writel(status, sdev->base + DMA_IRQ_STAT(i));
+
+		for (j = 0; (j < 8) && status; j++) {
+			if (status & DMA_IRQ_QUEUE) {
+				pchan = sdev->pchans + j;
+				vchan = pchan->vchan;
+
+				if (vchan) {
+					unsigned long flags;
+
+					spin_lock_irqsave(&vchan->vc.lock,
+							  flags);
+					vchan_cookie_complete(&pchan->desc->vd);
+					pchan->done = pchan->desc;
+					spin_unlock_irqrestore(&vchan->vc.lock,
+							       flags);
+				}
+			}
+
+			status = status >> 4;
+		}
+
+		ret |= IRQ_HANDLED;
+	}
+
+	if (ret == IRQ_HANDLED)
+		tasklet_schedule(&sdev->task);
+
+	return ret;
+}
+
+static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_memcpy(
+		struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
+		size_t len, unsigned long flags)
+{
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+	struct dma_slave_config *sconfig = &vchan->cfg;
+	struct sun6i_dma_lli *v_lli;
+	struct sun6i_desc *txd;
+	dma_addr_t p_lli;
+
+	dev_dbg(chan2dev(chan),
+		"%s; chan: %d, dest: 0x%08x, src: 0x%08x, len: 0x%08x. flags: 0x%08lx\n",
+		__func__, vchan->vc.chan.chan_id, dest, src, len, flags);
+
+	if (!len)
+		return NULL;
+
+	txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
+	if (!txd)
+		return NULL;
+
+	v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
+	if (!v_lli) {
+		dev_err(sdev->slave.dev, "Failed to alloc lli memory\n");
+		kfree(txd);
+		return NULL;
+	}
+
+	sun6i_dma_cfg_lli(v_lli, src, dest, len, sconfig);
+	v_lli->cfg |= DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
+		DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
+		DMA_CHAN_CFG_DST_LINEAR_MODE |
+		DMA_CHAN_CFG_SRC_LINEAR_MODE;
+
+	sun6i_dma_lli_add(NULL, v_lli, p_lli, txd);
+
+	sun6i_dma_dump_lli(vchan, v_lli);
+
+	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *sun6i_dma_prep_slave_sg(
+		struct dma_chan *chan, struct scatterlist *sgl,
+		unsigned int sg_len, enum dma_transfer_direction dir,
+		unsigned long flags, void *context)
+{
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+	struct dma_slave_config *sconfig = &vchan->cfg;
+	struct sun6i_dma_lli *v_lli, *prev = NULL;
+	struct sun6i_desc *txd;
+	struct scatterlist *sg;
+	dma_addr_t p_lli;
+	int i;
+
+	if (!sgl)
+		return NULL;
+
+	txd = kzalloc(sizeof(*txd), GFP_NOWAIT);
+	if (!txd)
+		return NULL;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		v_lli = dma_pool_alloc(sdev->pool, GFP_NOWAIT, &p_lli);
+		if (!v_lli) {
+			kfree(txd);
+			return NULL;
+		}
+
+		if (dir == DMA_MEM_TO_DEV) {
+			sun6i_dma_cfg_lli(v_lli, sg_dma_address(sg),
+					  sconfig->dst_addr, sg_dma_len(sg),
+					  sconfig);
+			v_lli->cfg |= DMA_CHAN_CFG_DST_IO_MODE |
+				DMA_CHAN_CFG_SRC_LINEAR_MODE |
+				DMA_CHAN_CFG_SRC_DRQ(DRQ_SDRAM) |
+				DMA_CHAN_CFG_DST_DRQ(vchan->port);
+
+			dev_dbg(chan2dev(chan), "%s; chan: %d, dest: 0x%08x, "
+				"src: 0x%08x, len: 0x%08x. flags: 0x%08lx\n",
+				__func__, vchan->vc.chan.chan_id,
+				sconfig->dst_addr, sg_dma_address(sg),
+				sg_dma_len(sg), flags);
+
+		} else if (dir == DMA_DEV_TO_MEM) {
+			sun6i_dma_cfg_lli(v_lli, sconfig->src_addr,
+					  sg_dma_address(sg), sg_dma_len(sg),
+					  sconfig);
+			v_lli->cfg |= DMA_CHAN_CFG_DST_LINEAR_MODE |
+				DMA_CHAN_CFG_SRC_IO_MODE |
+				DMA_CHAN_CFG_DST_DRQ(DRQ_SDRAM) |
+				DMA_CHAN_CFG_SRC_DRQ(vchan->port);
+
+			dev_dbg(chan2dev(chan), "%s; chan: %d, dest: 0x%08x, "
+				"src: 0x%08x, len: 0x%08x. flags: 0x%08lx\n",
+				__func__, vchan->vc.chan.chan_id,
+				sg_dma_address(sg), sconfig->src_addr,
+				sg_dma_len(sg), flags);
+		}
+
+		prev = sun6i_dma_lli_add(prev, v_lli, p_lli, txd);
+	}
+
+#ifdef DEBUG
+	dev_dbg(chan2dev(chan), "First: 0x%08x\n", txd->p_lli);
+	for (prev = txd->v_lli; prev != NULL; prev = prev->v_lli_next)
+		sun6i_dma_dump_lli(vchan, prev);
+#endif
+
+	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
+}
+
+static int sun6i_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+		       unsigned long arg)
+{
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+	struct sun6i_pchan *pchan = vchan->phy;
+	unsigned long flags;
+	int ret = 0;
+
+	switch (cmd) {
+	case DMA_RESUME:
+		dev_dbg(chan2dev(chan), "vchan %p: resume\n", &vchan->vc);
+
+		spin_lock_irqsave(&vchan->vc.lock, flags);
+
+		if (pchan) {
+			writel(DMA_CHAN_PAUSE_RESUME,
+			       pchan->base + DMA_CHAN_PAUSE);
+		} else if (!list_empty(&vchan->vc.desc_issued)) {
+			spin_lock(&sdev->lock);
+			list_add_tail(&vchan->node, &sdev->pending);
+			spin_unlock(&sdev->lock);
+		}
+
+		spin_unlock_irqrestore(&vchan->vc.lock, flags);
+		break;
+
+	case DMA_PAUSE:
+		dev_dbg(chan2dev(chan), "vchan %p: pause\n", &vchan->vc);
+
+		if (pchan) {
+			writel(DMA_CHAN_PAUSE_PAUSE,
+			       pchan->base + DMA_CHAN_PAUSE);
+		} else {
+			spin_lock(&sdev->lock);
+			list_del_init(&vchan->node);
+			spin_unlock(&sdev->lock);
+		}
+		break;
+
+	case DMA_TERMINATE_ALL:
+		ret = sun6i_dma_terminate_all(vchan);
+		break;
+	case DMA_SLAVE_CONFIG:
+		memcpy(&vchan->cfg, (struct dma_slave_config *)arg,
+		       sizeof(struct dma_slave_config));
+		break;
+	default:
+		ret = -ENXIO;
+		break;
+	}
+	return ret;
+}
+
+static enum dma_status sun6i_dma_tx_status(struct dma_chan *chan,
+					   dma_cookie_t cookie,
+					   struct dma_tx_state *state)
+{
+	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+	struct sun6i_pchan *pchan = vchan->phy;
+	struct sun6i_dma_lli *lli;
+	struct virt_dma_desc *vd;
+	struct sun6i_desc *txd;
+	enum dma_status ret;
+	unsigned long flags;
+	size_t bytes = 0;
+
+	ret = dma_cookie_status(chan, cookie, state);
+	if (ret == DMA_COMPLETE)
+		return ret;
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+
+	vd = vchan_find_desc(&vchan->vc, cookie);
+	txd = to_sun6i_desc(&vd->tx);
+
+	if (vd) {
+		for (lli = txd->v_lli; lli != NULL; lli = lli->v_lli_next)
+			bytes += lli->len;
+	} else if (!pchan || !pchan->desc) {
+		bytes = 0;
+	} else {
+		bytes = readl(pchan->base + DMA_CHAN_CUR_CNT);
+	}
+
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+
+	dma_set_residue(state, bytes);
+
+	return ret;
+}
+
+static void sun6i_dma_issue_pending(struct dma_chan *chan)
+{
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&vchan->vc.lock, flags);
+
+	if (vchan_issue_pending(&vchan->vc)) {
+		spin_lock(&sdev->lock);
+
+		if (!vchan->phy) {
+			if (list_empty(&vchan->node)) {
+				list_add_tail(&vchan->node, &sdev->pending);
+				tasklet_schedule(&sdev->task);
+				dev_dbg(chan2dev(chan), "vchan %p: issued\n",
+					&vchan->vc);
+			}
+		}
+
+		spin_unlock(&sdev->lock);
+	} else {
+		dev_dbg(chan2dev(chan), "vchan %p: nothing to issue\n",
+			&vchan->vc);
+	}
+
+	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+}
+
+static int sun6i_dma_alloc_chan_resources(struct dma_chan *chan)
+{
+	return 0;
+}
+
+static void sun6i_dma_free_chan_resources(struct dma_chan *chan)
+{
+	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
+	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&sdev->lock, flags);
+	list_del_init(&vchan->node);
+	spin_unlock_irqrestore(&sdev->lock, flags);
+
+	vchan_free_chan_resources(&vchan->vc);
+}
+
+static inline void sun6i_dma_free(struct sun6i_dma_dev *sdc)
+{
+	int i;
+
+	for (i = 0; i < NR_MAX_VCHANS; i++) {
+		struct sun6i_vchan *vchan = &sdc->vchans[i];
+
+		list_del(&vchan->vc.chan.device_node);
+		tasklet_kill(&vchan->vc.task);
+	}
+
+	tasklet_kill(&sdc->task);
+}
+
+static struct dma_chan *sun6i_dma_of_xlate(struct of_phandle_args *dma_spec,
+					   struct of_dma *ofdma)
+{
+	struct sun6i_dma_dev *sdev = ofdma->of_dma_data;
+	struct sun6i_vchan *vchan;
+	struct dma_chan *chan;
+	u8 port = dma_spec->args[0];
+
+	if (port > NR_MAX_REQUESTS)
+		return NULL;
+
+	chan = dma_get_any_slave_channel(&sdev->slave);
+	if (!chan)
+		return NULL;
+
+	vchan = to_sun6i_vchan(chan);
+	vchan->port = port;
+
+	return chan;
+}
+
+static int sun6i_dma_probe(struct platform_device *pdev)
+{
+	struct sun6i_dma_dev *sdc;
+	struct resource *res;
+	int irq;
+	int ret, i;
+
+	sdc = devm_kzalloc(&pdev->dev, sizeof(*sdc), GFP_KERNEL);
+	if (!sdc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	sdc->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(sdc->base))
+		return PTR_ERR(sdc->base);
+
+	irq = platform_get_irq(pdev, 0);
+	ret = devm_request_irq(&pdev->dev, irq, sun6i_dma_interrupt, 0,
+			       dev_name(&pdev->dev), sdc);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot request IRQ\n");
+		return ret;
+	}
+
+	sdc->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(sdc->clk)) {
+		dev_err(&pdev->dev, "No clock specified\n");
+		return PTR_ERR(sdc->clk);
+	}
+
+	sdc->rstc = devm_reset_control_get(&pdev->dev, NULL);
+	if (IS_ERR(sdc->rstc)) {
+		dev_err(&pdev->dev, "No reset controller specified\n");
+		return PTR_ERR(sdc->rstc);
+	}
+
+	sdc->pool = dma_pool_create(dev_name(&pdev->dev), &pdev->dev,
+					sizeof(struct sun6i_dma_lli), 4, 0);
+	if (!sdc->pool) {
+		dev_err(&pdev->dev, "No memory for descriptors dma pool\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, sdc);
+	INIT_LIST_HEAD(&sdc->pending);
+	spin_lock_init(&sdc->lock);
+
+	dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask);
+	dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask);
+	dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask);
+
+	INIT_LIST_HEAD(&sdc->slave.channels);
+	sdc->slave.device_alloc_chan_resources	= sun6i_dma_alloc_chan_resources;
+	sdc->slave.device_free_chan_resources	= sun6i_dma_free_chan_resources;
+	sdc->slave.device_tx_status		= sun6i_dma_tx_status;
+	sdc->slave.device_issue_pending		= sun6i_dma_issue_pending;
+	sdc->slave.device_prep_slave_sg		= sun6i_dma_prep_slave_sg;
+	sdc->slave.device_prep_dma_memcpy	= sun6i_dma_prep_dma_memcpy;
+	sdc->slave.device_control		= sun6i_dma_control;
+	sdc->slave.chancnt			= NR_MAX_VCHANS;
+
+	sdc->slave.dev = &pdev->dev;
+
+	sdc->pchans = devm_kzalloc(&pdev->dev,
+				   NR_MAX_CHANNELS * sizeof(struct sun6i_pchan),
+				   GFP_KERNEL);
+	if (!sdc->pchans) {
+		ret = -ENOMEM;
+		goto err_dma_pool_destroy;
+	}
+
+	sdc->vchans = devm_kzalloc(&pdev->dev,
+				   NR_MAX_VCHANS * sizeof(struct sun6i_vchan),
+				   GFP_KERNEL);
+	if (!sdc->vchans) {
+		ret = -ENOMEM;
+		goto err_dma_pool_destroy;
+	}
+
+	tasklet_init(&sdc->task, sun6i_dma_tasklet, (unsigned long)sdc);
+
+	for (i = 0; i < NR_MAX_CHANNELS; i++) {
+		struct sun6i_pchan *pchan = &sdc->pchans[i];
+
+		pchan->idx = i;
+		pchan->base = sdc->base + 0x100 + i * 0x40;
+	}
+
+	for (i = 0; i < NR_MAX_VCHANS; i++) {
+		struct sun6i_vchan *vchan = &sdc->vchans[i];
+
+		INIT_LIST_HEAD(&vchan->node);
+		vchan->vc.desc_free = sun6i_dma_free_desc;
+		vchan_init(&vchan->vc, &sdc->slave);
+	}
+
+	reset_control_deassert(sdc->rstc);
+
+	clk_prepare_enable(sdc->clk);
+
+	ret = dma_async_device_register(&sdc->slave);
+	if (ret) {
+		dev_warn(&pdev->dev, "Failed to register DMA engine device\n");
+		goto err_clk_disable;
+	}
+
+	ret = of_dma_controller_register(pdev->dev.of_node, sun6i_dma_of_xlate,
+					 sdc);
+	if (ret) {
+		dev_err(&pdev->dev, "of_dma_controller_register failed\n");
+		goto err_dma_unregister;
+	}
+
+	return 0;
+
+err_dma_unregister:
+	dma_async_device_unregister(&sdc->slave);
+err_clk_disable:
+	clk_disable_unprepare(sdc->clk);
+	reset_control_assert(sdc->rstc);
+	sun6i_dma_free(sdc);
+err_dma_pool_destroy:
+	dma_pool_destroy(sdc->pool);
+	return ret;
+}
+
+static int sun6i_dma_remove(struct platform_device *pdev)
+{
+	struct sun6i_dma_dev *sdc = platform_get_drvdata(pdev);
+
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&sdc->slave);
+
+	clk_disable_unprepare(sdc->clk);
+	reset_control_assert(sdc->rstc);
+
+	sun6i_dma_free(sdc);
+
+	dma_pool_destroy(sdc->pool);
+
+	return 0;
+}
+
+static struct of_device_id sun6i_dma_match[] = {
+	{ .compatible = "allwinner,sun6i-a31-dma" }
+};
+
+static struct platform_driver sun6i_dma_driver = {
+	.probe		= sun6i_dma_probe,
+	.remove		= sun6i_dma_remove,
+	.driver = {
+		.name		= "sun6i-dma",
+		.of_match_table	= sun6i_dma_match,
+	},
+};
+module_platform_driver(sun6i_dma_driver);
+
+MODULE_DESCRIPTION("Allwinner A31 DMA Controller Driver");
+MODULE_AUTHOR("Sugar <[e-mail]>");
+MODULE_AUTHOR("Maxime Ripard <[e-mail]>");
+MODULE_LICENSE("GPL");