drivers/dma/uniphier-mdmac.c - pub/scm/linux/kernel/git/geert/renesas-devel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 //
 // Copyright (C) 2018 Socionext Inc.
 //   Author: Masahiro Yamada <yamada.masahiro@socionext.com>

 #include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
 #include <linux/interrupt.h>
 #include <linux/iopoll.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_dma.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/types.h>

 #include "virt-dma.h"

 /* registers common for all channels */
 #define UNIPHIER_MDMAC_CMD		0x000	/* issue DMA start/abort */
 #define   UNIPHIER_MDMAC_CMD_ABORT		BIT(31) /* 1: abort, 0: start */

 /* per-channel registers */
 #define UNIPHIER_MDMAC_CH_OFFSET	0x100
 #define UNIPHIER_MDMAC_CH_STRIDE	0x040

 #define UNIPHIER_MDMAC_CH_IRQ_STAT	0x010	/* current hw status (RO) */
 #define UNIPHIER_MDMAC_CH_IRQ_REQ	0x014	/* latched STAT (WOC) */
 #define UNIPHIER_MDMAC_CH_IRQ_EN	0x018	/* IRQ enable mask */
 #define UNIPHIER_MDMAC_CH_IRQ_DET	0x01c	/* REQ & EN (RO) */
 #define   UNIPHIER_MDMAC_CH_IRQ__ABORT		BIT(13)
 #define   UNIPHIER_MDMAC_CH_IRQ__DONE		BIT(1)
 #define UNIPHIER_MDMAC_CH_SRC_MODE	0x020	/* mode of source */
 #define UNIPHIER_MDMAC_CH_DEST_MODE	0x024	/* mode of destination */
 #define   UNIPHIER_MDMAC_CH_MODE__ADDR_INC	(0 << 4)
 #define   UNIPHIER_MDMAC_CH_MODE__ADDR_DEC	(1 << 4)
 #define   UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED	(2 << 4)
 #define UNIPHIER_MDMAC_CH_SRC_ADDR	0x028	/* source address */
 #define UNIPHIER_MDMAC_CH_DEST_ADDR	0x02c	/* destination address */
 #define UNIPHIER_MDMAC_CH_SIZE		0x030	/* transfer bytes */

 #define UNIPHIER_MDMAC_SLAVE_BUSWIDTHS \
 	(BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | \
 	 BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
 	 BIT(DMA_SLAVE_BUSWIDTH_3_BYTES) | \
 	 BIT(DMA_SLAVE_BUSWIDTH_4_BYTES))

 struct uniphier_mdmac_desc {
 	struct virt_dma_desc vd;
 	struct scatterlist *sgl;
 	unsigned int sg_len;
 	unsigned int sg_cur;
 	enum dma_transfer_direction dir;
 };

 struct uniphier_mdmac_chan {
 	struct virt_dma_chan vc;
 	struct uniphier_mdmac_device *mdev;
 	struct uniphier_mdmac_desc *md;
 	void __iomem *reg_ch_base;
 	unsigned int chan_id;
 };

 struct uniphier_mdmac_device {
 	struct dma_device ddev;
 	struct clk *clk;
 	void __iomem *reg_base;
 	struct uniphier_mdmac_chan channels[];
 };

 static struct uniphier_mdmac_chan *
 to_uniphier_mdmac_chan(struct virt_dma_chan *vc)
 {
 	return container_of(vc, struct uniphier_mdmac_chan, vc);
 }

 static struct uniphier_mdmac_desc *
 to_uniphier_mdmac_desc(struct virt_dma_desc *vd)
 {
 	return container_of(vd, struct uniphier_mdmac_desc, vd);
 }

 /* mc->vc.lock must be held by caller */
 static struct uniphier_mdmac_desc *
 uniphier_mdmac_next_desc(struct uniphier_mdmac_chan *mc)
 {
 	struct virt_dma_desc *vd;

 	vd = vchan_next_desc(&mc->vc);
 	if (!vd) {
 		mc->md = NULL;
 		return NULL;
 	}

 	list_del(&vd->node);

 	mc->md = to_uniphier_mdmac_desc(vd);

 	return mc->md;
 }

 /* mc->vc.lock must be held by caller */
 static void uniphier_mdmac_handle(struct uniphier_mdmac_chan *mc,
 				  struct uniphier_mdmac_desc *md)
 {
 	struct uniphier_mdmac_device *mdev = mc->mdev;
 	struct scatterlist *sg;
 	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__DONE;
 	u32 src_mode, src_addr, dest_mode, dest_addr, chunk_size;

 	sg = &md->sgl[md->sg_cur];

 	if (md->dir == DMA_MEM_TO_DEV) {
 		src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
 		src_addr = sg_dma_address(sg);
 		dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
 		dest_addr = 0;
 	} else {
 		src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
 		src_addr = 0;
 		dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
 		dest_addr = sg_dma_address(sg);
 	}

 	chunk_size = sg_dma_len(sg);

 	writel(src_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_MODE);
 	writel(dest_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_MODE);
 	writel(src_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_ADDR);
 	writel(dest_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_ADDR);
 	writel(chunk_size, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SIZE);

 	/* write 1 to clear */
 	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);

 	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_EN);

 	writel(BIT(mc->chan_id), mdev->reg_base + UNIPHIER_MDMAC_CMD);
 }

 /* mc->vc.lock must be held by caller */
 static void uniphier_mdmac_start(struct uniphier_mdmac_chan *mc)
 {
 	struct uniphier_mdmac_desc *md;

 	md = uniphier_mdmac_next_desc(mc);
 	if (md)
 		uniphier_mdmac_handle(mc, md);
 }

 /* mc->vc.lock must be held by caller */
 static int uniphier_mdmac_abort(struct uniphier_mdmac_chan *mc)
 {
 	struct uniphier_mdmac_device *mdev = mc->mdev;
 	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__ABORT;
 	u32 val;

 	/* write 1 to clear */
 	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);

 	writel(UNIPHIER_MDMAC_CMD_ABORT | BIT(mc->chan_id),
 	       mdev->reg_base + UNIPHIER_MDMAC_CMD);

 	/*
 	 * Abort should be accepted soon. We poll the bit here instead of
 	 * waiting for the interrupt.
 	 */
 	return readl_poll_timeout(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ,
 				  val, val & irq_flag, 0, 20);
 }

 static irqreturn_t uniphier_mdmac_interrupt(int irq, void *dev_id)
 {
 	struct uniphier_mdmac_chan *mc = dev_id;
 	struct uniphier_mdmac_desc *md;
 	irqreturn_t ret = IRQ_HANDLED;
 	u32 irq_stat;

 	spin_lock(&mc->vc.lock);

 	irq_stat = readl(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_DET);

 	/*
 	 * Some channels share a single interrupt line. If the IRQ status is 0,
 	 * this is probably triggered by a different channel.
 	 */
 	if (!irq_stat) {
 		ret = IRQ_NONE;
 		goto out;
 	}

 	/* write 1 to clear */
 	writel(irq_stat, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);

 	/*
 	 * UNIPHIER_MDMAC_CH_IRQ__DONE interrupt is asserted even when the DMA
 	 * is aborted. To distinguish the normal completion and the abort,
 	 * check mc->md. If it is NULL, we are aborting.
 	 */
 	md = mc->md;
 	if (!md)
 		goto out;

 	md->sg_cur++;

 	if (md->sg_cur >= md->sg_len) {
 		vchan_cookie_complete(&md->vd);
 		md = uniphier_mdmac_next_desc(mc);
 		if (!md)
 			goto out;
 	}

 	uniphier_mdmac_handle(mc, md);

 out:
 	spin_unlock(&mc->vc.lock);

 	return ret;
 }

 static void uniphier_mdmac_free_chan_resources(struct dma_chan *chan)
 {
 	vchan_free_chan_resources(to_virt_chan(chan));
 }

 static struct dma_async_tx_descriptor *
 uniphier_mdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 			     unsigned int sg_len,
 			     enum dma_transfer_direction direction,
 			     unsigned long flags, void *context)
 {
 	struct virt_dma_chan *vc = to_virt_chan(chan);
 	struct uniphier_mdmac_desc *md;

 	if (!is_slave_direction(direction))
 		return NULL;

 	md = kzalloc(sizeof(*md), GFP_NOWAIT);
 	if (!md)
 		return NULL;

 	md->sgl = sgl;
 	md->sg_len = sg_len;
 	md->dir = direction;

 	return vchan_tx_prep(vc, &md->vd, flags);
 }

 static int uniphier_mdmac_terminate_all(struct dma_chan *chan)
 {
 	struct virt_dma_chan *vc = to_virt_chan(chan);
 	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
 	unsigned long flags;
 	int ret = 0;
 	LIST_HEAD(head);

 	spin_lock_irqsave(&vc->lock, flags);

 	if (mc->md) {
 		vchan_terminate_vdesc(&mc->md->vd);
 		mc->md = NULL;
 		ret = uniphier_mdmac_abort(mc);
 	}
 	vchan_get_all_descriptors(vc, &head);

 	spin_unlock_irqrestore(&vc->lock, flags);

 	vchan_dma_desc_free_list(vc, &head);

 	return ret;
 }

 static void uniphier_mdmac_synchronize(struct dma_chan *chan)
 {
 	vchan_synchronize(to_virt_chan(chan));
 }

 static enum dma_status uniphier_mdmac_tx_status(struct dma_chan *chan,
 						dma_cookie_t cookie,
 						struct dma_tx_state *txstate)
 {
 	struct virt_dma_chan *vc;
 	struct virt_dma_desc *vd;
 	struct uniphier_mdmac_chan *mc;
 	struct uniphier_mdmac_desc *md = NULL;
 	enum dma_status stat;
 	unsigned long flags;
 	int i;

 	stat = dma_cookie_status(chan, cookie, txstate);
 	/* Return immediately if we do not need to compute the residue. */
 	if (stat == DMA_COMPLETE || !txstate)
 		return stat;

 	vc = to_virt_chan(chan);

 	spin_lock_irqsave(&vc->lock, flags);

 	mc = to_uniphier_mdmac_chan(vc);

 	if (mc->md && mc->md->vd.tx.cookie == cookie) {
 		/* residue from the on-flight chunk */
 		txstate->residue = readl(mc->reg_ch_base +
 					 UNIPHIER_MDMAC_CH_SIZE);
 		md = mc->md;
 	}

 	if (!md) {
 		vd = vchan_find_desc(vc, cookie);
 		if (vd)
 			md = to_uniphier_mdmac_desc(vd);
 	}

 	if (md) {
 		/* residue from the queued chunks */
 		for (i = md->sg_cur; i < md->sg_len; i++)
 			txstate->residue += sg_dma_len(&md->sgl[i]);
 	}

 	spin_unlock_irqrestore(&vc->lock, flags);

 	return stat;
 }

 static void uniphier_mdmac_issue_pending(struct dma_chan *chan)
 {
 	struct virt_dma_chan *vc = to_virt_chan(chan);
 	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
 	unsigned long flags;

 	spin_lock_irqsave(&vc->lock, flags);

 	if (vchan_issue_pending(vc) && !mc->md)
 		uniphier_mdmac_start(mc);

 	spin_unlock_irqrestore(&vc->lock, flags);
 }

 static void uniphier_mdmac_desc_free(struct virt_dma_desc *vd)
 {
 	kfree(to_uniphier_mdmac_desc(vd));
 }

 static int uniphier_mdmac_chan_init(struct platform_device *pdev,
 				    struct uniphier_mdmac_device *mdev,
 				    int chan_id)
 {
 	struct device *dev = &pdev->dev;
 	struct uniphier_mdmac_chan *mc = &mdev->channels[chan_id];
 	char *irq_name;
 	int irq, ret;

 	irq = platform_get_irq(pdev, chan_id);
 	if (irq < 0)
 		return irq;

 	irq_name = devm_kasprintf(dev, GFP_KERNEL, "uniphier-mio-dmac-ch%d",
 				  chan_id);
 	if (!irq_name)
 		return -ENOMEM;

 	ret = devm_request_irq(dev, irq, uniphier_mdmac_interrupt,
 			       IRQF_SHARED, irq_name, mc);
 	if (ret)
 		return ret;

 	mc->mdev = mdev;
 	mc->reg_ch_base = mdev->reg_base + UNIPHIER_MDMAC_CH_OFFSET +
 					UNIPHIER_MDMAC_CH_STRIDE * chan_id;
 	mc->chan_id = chan_id;
 	mc->vc.desc_free = uniphier_mdmac_desc_free;
 	vchan_init(&mc->vc, &mdev->ddev);

 	return 0;
 }

 static int uniphier_mdmac_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct uniphier_mdmac_device *mdev;
 	struct dma_device *ddev;
 	int nr_chans, ret, i;

 	nr_chans = platform_irq_count(pdev);
 	if (nr_chans < 0)
 		return nr_chans;

 	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
 	if (ret)
 		return ret;

 	mdev = devm_kzalloc(dev, struct_size(mdev, channels, nr_chans),
 			    GFP_KERNEL);
 	if (!mdev)
 		return -ENOMEM;

 	mdev->reg_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(mdev->reg_base))
 		return PTR_ERR(mdev->reg_base);

 	mdev->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(mdev->clk)) {
 		dev_err(dev, "failed to get clock\n");
 		return PTR_ERR(mdev->clk);
 	}

 	ret = clk_prepare_enable(mdev->clk);
 	if (ret)
 		return ret;

 	ddev = &mdev->ddev;
 	ddev->dev = dev;
 	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
 	ddev->src_addr_widths = UNIPHIER_MDMAC_SLAVE_BUSWIDTHS;
 	ddev->dst_addr_widths = UNIPHIER_MDMAC_SLAVE_BUSWIDTHS;
 	ddev->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
 	ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
 	ddev->device_free_chan_resources = uniphier_mdmac_free_chan_resources;
 	ddev->device_prep_slave_sg = uniphier_mdmac_prep_slave_sg;
 	ddev->device_terminate_all = uniphier_mdmac_terminate_all;
 	ddev->device_synchronize = uniphier_mdmac_synchronize;
 	ddev->device_tx_status = uniphier_mdmac_tx_status;
 	ddev->device_issue_pending = uniphier_mdmac_issue_pending;
 	INIT_LIST_HEAD(&ddev->channels);

 	for (i = 0; i < nr_chans; i++) {
 		ret = uniphier_mdmac_chan_init(pdev, mdev, i);
 		if (ret)
 			goto disable_clk;
 	}

 	ret = dma_async_device_register(ddev);
 	if (ret)
 		goto disable_clk;

 	ret = of_dma_controller_register(dev->of_node, of_dma_xlate_by_chan_id,
 					 ddev);
 	if (ret)
 		goto unregister_dmac;

 	platform_set_drvdata(pdev, mdev);

 	return 0;

 unregister_dmac:
 	dma_async_device_unregister(ddev);
 disable_clk:
 	clk_disable_unprepare(mdev->clk);

 	return ret;
 }

 static void uniphier_mdmac_remove(struct platform_device *pdev)
 {
 	struct uniphier_mdmac_device *mdev = platform_get_drvdata(pdev);
 	struct dma_chan *chan;
 	int ret;

 	/*
 	 * Before reaching here, almost all descriptors have been freed by the
 	 * ->device_free_chan_resources() hook. However, each channel might
 	 * be still holding one descriptor that was on-flight at that moment.
 	 * Terminate it to make sure this hardware is no longer running. Then,
 	 * free the channel resources once again to avoid memory leak.
 	 */
 	list_for_each_entry(chan, &mdev->ddev.channels, device_node) {
 		ret = dmaengine_terminate_sync(chan);
 		if (ret) {
 			/*
 			 * This results in resource leakage and maybe also
 			 * use-after-free errors as e.g. *mdev is kfreed.
 			 */
 			dev_alert(&pdev->dev, "Failed to terminate channel %d (%pe)\n",
 				  chan->chan_id, ERR_PTR(ret));
 			return;
 		}
 		uniphier_mdmac_free_chan_resources(chan);
 	}

 	of_dma_controller_free(pdev->dev.of_node);
 	dma_async_device_unregister(&mdev->ddev);
 	clk_disable_unprepare(mdev->clk);
 }

 static const struct of_device_id uniphier_mdmac_match[] = {
 	{ .compatible = "socionext,uniphier-mio-dmac" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, uniphier_mdmac_match);

 static struct platform_driver uniphier_mdmac_driver = {
 	.probe = uniphier_mdmac_probe,
 	.remove = uniphier_mdmac_remove,
 	.driver = {
 		.name = "uniphier-mio-dmac",
 		.of_match_table = uniphier_mdmac_match,
 	},
 };
 module_platform_driver(uniphier_mdmac_driver);

 MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
 MODULE_DESCRIPTION("UniPhier MIO DMAC driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	//
	// Copyright (C) 2018 Socionext Inc.
	// Author: Masahiro Yamada <yamada.masahiro@socionext.com>

	#include <linux/bits.h>
	#include <linux/clk.h>
	#include <linux/dma-mapping.h>
	#include <linux/dmaengine.h>
	#include <linux/interrupt.h>
	#include <linux/iopoll.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_dma.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/types.h>

	#include "virt-dma.h"

	/* registers common for all channels */
	#define UNIPHIER_MDMAC_CMD 0x000 /* issue DMA start/abort */
	#define UNIPHIER_MDMAC_CMD_ABORT BIT(31) /* 1: abort, 0: start */

	/* per-channel registers */
	#define UNIPHIER_MDMAC_CH_OFFSET 0x100
	#define UNIPHIER_MDMAC_CH_STRIDE 0x040

	#define UNIPHIER_MDMAC_CH_IRQ_STAT 0x010 /* current hw status (RO) */
	#define UNIPHIER_MDMAC_CH_IRQ_REQ 0x014 /* latched STAT (WOC) */
	#define UNIPHIER_MDMAC_CH_IRQ_EN 0x018 /* IRQ enable mask */
	#define UNIPHIER_MDMAC_CH_IRQ_DET 0x01c /* REQ & EN (RO) */
	#define UNIPHIER_MDMAC_CH_IRQ__ABORT BIT(13)
	#define UNIPHIER_MDMAC_CH_IRQ__DONE BIT(1)
	#define UNIPHIER_MDMAC_CH_SRC_MODE 0x020 /* mode of source */
	#define UNIPHIER_MDMAC_CH_DEST_MODE 0x024 /* mode of destination */
	#define UNIPHIER_MDMAC_CH_MODE__ADDR_INC (0 << 4)
	#define UNIPHIER_MDMAC_CH_MODE__ADDR_DEC (1 << 4)
	#define UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED (2 << 4)
	#define UNIPHIER_MDMAC_CH_SRC_ADDR 0x028 /* source address */
	#define UNIPHIER_MDMAC_CH_DEST_ADDR 0x02c /* destination address */
	#define UNIPHIER_MDMAC_CH_SIZE 0x030 /* transfer bytes */

	#define UNIPHIER_MDMAC_SLAVE_BUSWIDTHS \
	(BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) \| \
	BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) \| \
	BIT(DMA_SLAVE_BUSWIDTH_3_BYTES) \| \
	BIT(DMA_SLAVE_BUSWIDTH_4_BYTES))

	struct uniphier_mdmac_desc {
	struct virt_dma_desc vd;
	struct scatterlist *sgl;
	unsigned int sg_len;
	unsigned int sg_cur;
	enum dma_transfer_direction dir;
	};

	struct uniphier_mdmac_chan {
	struct virt_dma_chan vc;
	struct uniphier_mdmac_device *mdev;
	struct uniphier_mdmac_desc *md;
	void __iomem *reg_ch_base;
	unsigned int chan_id;
	};

	struct uniphier_mdmac_device {
	struct dma_device ddev;
	struct clk *clk;
	void __iomem *reg_base;
	struct uniphier_mdmac_chan channels[];
	};

	static struct uniphier_mdmac_chan *
	to_uniphier_mdmac_chan(struct virt_dma_chan *vc)
	{
	return container_of(vc, struct uniphier_mdmac_chan, vc);
	}

	static struct uniphier_mdmac_desc *
	to_uniphier_mdmac_desc(struct virt_dma_desc *vd)
	{
	return container_of(vd, struct uniphier_mdmac_desc, vd);
	}

	/* mc->vc.lock must be held by caller */
	static struct uniphier_mdmac_desc *
	uniphier_mdmac_next_desc(struct uniphier_mdmac_chan *mc)
	{
	struct virt_dma_desc *vd;

	vd = vchan_next_desc(&mc->vc);
	if (!vd) {
	mc->md = NULL;
	return NULL;
	}

	list_del(&vd->node);

	mc->md = to_uniphier_mdmac_desc(vd);

	return mc->md;
	}

	/* mc->vc.lock must be held by caller */
	static void uniphier_mdmac_handle(struct uniphier_mdmac_chan *mc,
	struct uniphier_mdmac_desc *md)
	{
	struct uniphier_mdmac_device *mdev = mc->mdev;
	struct scatterlist *sg;
	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__DONE;
	u32 src_mode, src_addr, dest_mode, dest_addr, chunk_size;

	sg = &md->sgl[md->sg_cur];

	if (md->dir == DMA_MEM_TO_DEV) {
	src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
	src_addr = sg_dma_address(sg);
	dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
	dest_addr = 0;
	} else {
	src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
	src_addr = 0;
	dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
	dest_addr = sg_dma_address(sg);
	}

	chunk_size = sg_dma_len(sg);

	writel(src_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_MODE);
	writel(dest_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_MODE);
	writel(src_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_ADDR);
	writel(dest_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_ADDR);
	writel(chunk_size, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SIZE);

	/* write 1 to clear */
	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);

	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_EN);

	writel(BIT(mc->chan_id), mdev->reg_base + UNIPHIER_MDMAC_CMD);
	}

	/* mc->vc.lock must be held by caller */
	static void uniphier_mdmac_start(struct uniphier_mdmac_chan *mc)
	{
	struct uniphier_mdmac_desc *md;

	md = uniphier_mdmac_next_desc(mc);
	if (md)
	uniphier_mdmac_handle(mc, md);
	}

	/* mc->vc.lock must be held by caller */
	static int uniphier_mdmac_abort(struct uniphier_mdmac_chan *mc)
	{
	struct uniphier_mdmac_device *mdev = mc->mdev;
	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__ABORT;
	u32 val;

	/* write 1 to clear */
	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);

	writel(UNIPHIER_MDMAC_CMD_ABORT \| BIT(mc->chan_id),
	mdev->reg_base + UNIPHIER_MDMAC_CMD);

	/*
	* Abort should be accepted soon. We poll the bit here instead of
	* waiting for the interrupt.
	*/
	return readl_poll_timeout(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ,
	val, val & irq_flag, 0, 20);
	}

	static irqreturn_t uniphier_mdmac_interrupt(int irq, void *dev_id)
	{
	struct uniphier_mdmac_chan *mc = dev_id;
	struct uniphier_mdmac_desc *md;
	irqreturn_t ret = IRQ_HANDLED;
	u32 irq_stat;

	spin_lock(&mc->vc.lock);

	irq_stat = readl(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_DET);

	/*
	* Some channels share a single interrupt line. If the IRQ status is 0,
	* this is probably triggered by a different channel.
	*/
	if (!irq_stat) {
	ret = IRQ_NONE;
	goto out;
	}

	/* write 1 to clear */
	writel(irq_stat, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);

	/*
	* UNIPHIER_MDMAC_CH_IRQ__DONE interrupt is asserted even when the DMA
	* is aborted. To distinguish the normal completion and the abort,
	* check mc->md. If it is NULL, we are aborting.
	*/
	md = mc->md;
	if (!md)
	goto out;

	md->sg_cur++;

	if (md->sg_cur >= md->sg_len) {
	vchan_cookie_complete(&md->vd);
	md = uniphier_mdmac_next_desc(mc);
	if (!md)
	goto out;
	}

	uniphier_mdmac_handle(mc, md);

	out:
	spin_unlock(&mc->vc.lock);

	return ret;
	}

	static void uniphier_mdmac_free_chan_resources(struct dma_chan *chan)
	{
	vchan_free_chan_resources(to_virt_chan(chan));
	}

	static struct dma_async_tx_descriptor *
	uniphier_mdmac_prep_slave_sg(struct dma_chan chan, struct scatterlist sgl,
	unsigned int sg_len,
	enum dma_transfer_direction direction,
	unsigned long flags, void *context)
	{
	struct virt_dma_chan *vc = to_virt_chan(chan);
	struct uniphier_mdmac_desc *md;

	if (!is_slave_direction(direction))
	return NULL;

	md = kzalloc(sizeof(*md), GFP_NOWAIT);
	if (!md)
	return NULL;

	md->sgl = sgl;
	md->sg_len = sg_len;
	md->dir = direction;

	return vchan_tx_prep(vc, &md->vd, flags);
	}

	static int uniphier_mdmac_terminate_all(struct dma_chan *chan)
	{
	struct virt_dma_chan *vc = to_virt_chan(chan);
	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
	unsigned long flags;
	int ret = 0;
	LIST_HEAD(head);

	spin_lock_irqsave(&vc->lock, flags);

	if (mc->md) {
	vchan_terminate_vdesc(&mc->md->vd);
	mc->md = NULL;
	ret = uniphier_mdmac_abort(mc);
	}
	vchan_get_all_descriptors(vc, &head);

	spin_unlock_irqrestore(&vc->lock, flags);

	vchan_dma_desc_free_list(vc, &head);

	return ret;
	}

	static void uniphier_mdmac_synchronize(struct dma_chan *chan)
	{
	vchan_synchronize(to_virt_chan(chan));
	}

	static enum dma_status uniphier_mdmac_tx_status(struct dma_chan *chan,
	dma_cookie_t cookie,
	struct dma_tx_state *txstate)
	{
	struct virt_dma_chan *vc;
	struct virt_dma_desc *vd;
	struct uniphier_mdmac_chan *mc;
	struct uniphier_mdmac_desc *md = NULL;
	enum dma_status stat;
	unsigned long flags;
	int i;

	stat = dma_cookie_status(chan, cookie, txstate);
	/* Return immediately if we do not need to compute the residue. */
	if (stat == DMA_COMPLETE \|\| !txstate)
	return stat;

	vc = to_virt_chan(chan);

	spin_lock_irqsave(&vc->lock, flags);

	mc = to_uniphier_mdmac_chan(vc);

	if (mc->md && mc->md->vd.tx.cookie == cookie) {
	/* residue from the on-flight chunk */
	txstate->residue = readl(mc->reg_ch_base +
	UNIPHIER_MDMAC_CH_SIZE);
	md = mc->md;
	}

	if (!md) {
	vd = vchan_find_desc(vc, cookie);
	if (vd)
	md = to_uniphier_mdmac_desc(vd);
	}

	if (md) {
	/* residue from the queued chunks */
	for (i = md->sg_cur; i < md->sg_len; i++)
	txstate->residue += sg_dma_len(&md->sgl[i]);
	}

	spin_unlock_irqrestore(&vc->lock, flags);

	return stat;
	}

	static void uniphier_mdmac_issue_pending(struct dma_chan *chan)
	{
	struct virt_dma_chan *vc = to_virt_chan(chan);
	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
	unsigned long flags;

	spin_lock_irqsave(&vc->lock, flags);

	if (vchan_issue_pending(vc) && !mc->md)
	uniphier_mdmac_start(mc);

	spin_unlock_irqrestore(&vc->lock, flags);
	}

	static void uniphier_mdmac_desc_free(struct virt_dma_desc *vd)
	{
	kfree(to_uniphier_mdmac_desc(vd));
	}

	static int uniphier_mdmac_chan_init(struct platform_device *pdev,
	struct uniphier_mdmac_device *mdev,
	int chan_id)
	{
	struct device *dev = &pdev->dev;
	struct uniphier_mdmac_chan *mc = &mdev->channels[chan_id];
	char *irq_name;
	int irq, ret;

	irq = platform_get_irq(pdev, chan_id);
	if (irq < 0)
	return irq;

	irq_name = devm_kasprintf(dev, GFP_KERNEL, "uniphier-mio-dmac-ch%d",
	chan_id);
	if (!irq_name)
	return -ENOMEM;

	ret = devm_request_irq(dev, irq, uniphier_mdmac_interrupt,
	IRQF_SHARED, irq_name, mc);
	if (ret)
	return ret;

	mc->mdev = mdev;
	mc->reg_ch_base = mdev->reg_base + UNIPHIER_MDMAC_CH_OFFSET +
	UNIPHIER_MDMAC_CH_STRIDE * chan_id;
	mc->chan_id = chan_id;
	mc->vc.desc_free = uniphier_mdmac_desc_free;
	vchan_init(&mc->vc, &mdev->ddev);

	return 0;
	}

	static int uniphier_mdmac_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct uniphier_mdmac_device *mdev;
	struct dma_device *ddev;
	int nr_chans, ret, i;

	nr_chans = platform_irq_count(pdev);
	if (nr_chans < 0)
	return nr_chans;

	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
	if (ret)
	return ret;

	mdev = devm_kzalloc(dev, struct_size(mdev, channels, nr_chans),
	GFP_KERNEL);
	if (!mdev)
	return -ENOMEM;

	mdev->reg_base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(mdev->reg_base))
	return PTR_ERR(mdev->reg_base);

	mdev->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(mdev->clk)) {
	dev_err(dev, "failed to get clock\n");
	return PTR_ERR(mdev->clk);
	}

	ret = clk_prepare_enable(mdev->clk);
	if (ret)
	return ret;

	ddev = &mdev->ddev;
	ddev->dev = dev;
	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
	ddev->src_addr_widths = UNIPHIER_MDMAC_SLAVE_BUSWIDTHS;
	ddev->dst_addr_widths = UNIPHIER_MDMAC_SLAVE_BUSWIDTHS;
	ddev->directions = BIT(DMA_MEM_TO_DEV) \| BIT(DMA_DEV_TO_MEM);
	ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
	ddev->device_free_chan_resources = uniphier_mdmac_free_chan_resources;
	ddev->device_prep_slave_sg = uniphier_mdmac_prep_slave_sg;
	ddev->device_terminate_all = uniphier_mdmac_terminate_all;
	ddev->device_synchronize = uniphier_mdmac_synchronize;
	ddev->device_tx_status = uniphier_mdmac_tx_status;
	ddev->device_issue_pending = uniphier_mdmac_issue_pending;
	INIT_LIST_HEAD(&ddev->channels);

	for (i = 0; i < nr_chans; i++) {
	ret = uniphier_mdmac_chan_init(pdev, mdev, i);
	if (ret)
	goto disable_clk;
	}

	ret = dma_async_device_register(ddev);
	if (ret)
	goto disable_clk;

	ret = of_dma_controller_register(dev->of_node, of_dma_xlate_by_chan_id,
	ddev);
	if (ret)
	goto unregister_dmac;

	platform_set_drvdata(pdev, mdev);

	return 0;

	unregister_dmac:
	dma_async_device_unregister(ddev);
	disable_clk:
	clk_disable_unprepare(mdev->clk);

	return ret;
	}

	static void uniphier_mdmac_remove(struct platform_device *pdev)
	{
	struct uniphier_mdmac_device *mdev = platform_get_drvdata(pdev);
	struct dma_chan *chan;
	int ret;

	/*
	* Before reaching here, almost all descriptors have been freed by the
	* ->device_free_chan_resources() hook. However, each channel might
	* be still holding one descriptor that was on-flight at that moment.
	* Terminate it to make sure this hardware is no longer running. Then,
	* free the channel resources once again to avoid memory leak.
	*/
	list_for_each_entry(chan, &mdev->ddev.channels, device_node) {
	ret = dmaengine_terminate_sync(chan);
	if (ret) {
	/*
	* This results in resource leakage and maybe also
	* use-after-free errors as e.g. *mdev is kfreed.
	*/
	dev_alert(&pdev->dev, "Failed to terminate channel %d (%pe)\n",
	chan->chan_id, ERR_PTR(ret));
	return;
	}
	uniphier_mdmac_free_chan_resources(chan);
	}

	of_dma_controller_free(pdev->dev.of_node);
	dma_async_device_unregister(&mdev->ddev);
	clk_disable_unprepare(mdev->clk);
	}

	static const struct of_device_id uniphier_mdmac_match[] = {
	{ .compatible = "socionext,uniphier-mio-dmac" },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, uniphier_mdmac_match);

	static struct platform_driver uniphier_mdmac_driver = {
	.probe = uniphier_mdmac_probe,
	.remove = uniphier_mdmac_remove,
	.driver = {
	.name = "uniphier-mio-dmac",
	.of_match_table = uniphier_mdmac_match,
	},
	};
	module_platform_driver(uniphier_mdmac_driver);

	MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
	MODULE_DESCRIPTION("UniPhier MIO DMAC driver");
	MODULE_LICENSE("GPL v2");