[PATCH 2/2] dmaengine: add union chan_dev for dma_chan::dev for clarity

[Frank.Li@oss.nxp.com]

From: Frank Li <Frank.Li@nxp.com>

The current dma_chan structure contains both "device" and "dev". So

chan->device->dev refers to the DMA engine device.
chan->dev->device refers to the per-channel device instance.

Their similar naming makes the distinction unclear and increases reader
confusion.

Add union dma_chan::chan_dev to make its purpose explicit and clearly
identify it as the per-channel device. After all user switch to chan_dev,
union and dma_chan::dev will be removed.

Update the kernel-doc accordingly. Besides its sysfs usage, the per-channel
device is also used by some DMA engine drivers for IOMMU mapping and
therefore deserves a more accurate description.

No functional change intended.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
there are other user use it outside drivers/dma/ directory.
---
 drivers/dma/at_hdmac.c                       |  2 +-
 drivers/dma/at_xdmac.c                       |  2 +-
 drivers/dma/dma-jz4780.c                     |  8 ++---
 drivers/dma/dmaengine.c                      | 34 +++++++++---------
 drivers/dma/dw-axi-dmac/dw-axi-dmac.h        |  4 +--
 drivers/dma/dw/core.c                        |  2 +-
 drivers/dma/ep93xx_dma.c                     |  2 +-
 drivers/dma/idma64.c                         |  2 +-
 drivers/dma/loongson/loongson1-apb-dma.c     |  2 +-
 drivers/dma/loongson/loongson2-apb-cmc-dma.c |  2 +-
 drivers/dma/loongson/loongson2-apb-dma.c     |  2 +-
 drivers/dma/nbpfaxi.c                        |  2 +-
 drivers/dma/owl-dma.c                        |  2 +-
 drivers/dma/pch_dma.c                        |  2 +-
 drivers/dma/pxa_dma.c                        | 52 ++++++++++++++--------------
 drivers/dma/stm32/stm32-dma.c                |  2 +-
 drivers/dma/stm32/stm32-dma3.c               |  2 +-
 drivers/dma/stm32/stm32-mdma.c               |  2 +-
 drivers/dma/sun6i-dma.c                      |  2 +-
 drivers/dma/switchtec_dma.c                  | 14 ++++----
 drivers/dma/tegra186-gpc-dma.c               |  4 +--
 drivers/dma/tegra20-apb-dma.c                |  2 +-
 drivers/dma/ti/k3-udma.c                     |  6 ++--
 drivers/dma/timb_dma.c                       |  2 +-
 include/linux/dmaengine.h                    | 18 +++++++---
 25 files changed, 91 insertions(+), 83 deletions(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index e5b30a57c477a..63c72f80d9a02 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -383,7 +383,7 @@ static inline struct at_dma *to_at_dma(struct dma_device *ddev)
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 #if defined(VERBOSE_DEBUG)
diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 901971e8bae69..30ec996845ce7 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -326,7 +326,7 @@ static inline struct at_xdmac_chan *to_at_xdmac_chan(struct dma_chan *dchan)
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 static inline struct at_xdmac *to_at_xdmac(struct dma_device *ddev)
diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index 194649811d02b..c48a46b2bbbf2 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -687,12 +687,12 @@ static bool jz4780_dma_chan_irq(struct jz4780_dma_dev *jzdma,
 	jz4780_dma_chn_writel(jzdma, jzchan->id, JZ_DMA_REG_DCS, 0);
 
 	if (dcs & JZ_DMA_DCS_AR) {
-		dev_warn(&jzchan->vchan.chan.dev->device,
+		dev_warn(&jzchan->vchan.chan.chan_dev->device,
 			 "address error (DCS=0x%x)\n", dcs);
 	}
 
 	if (dcs & JZ_DMA_DCS_HLT) {
-		dev_warn(&jzchan->vchan.chan.dev->device,
+		dev_warn(&jzchan->vchan.chan.chan_dev->device,
 			 "channel halt (DCS=0x%x)\n", dcs);
 	}
 
@@ -721,7 +721,7 @@ static bool jz4780_dma_chan_irq(struct jz4780_dma_dev *jzdma,
 			}
 		}
 	} else {
-		dev_err(&jzchan->vchan.chan.dev->device,
+		dev_err(&jzchan->vchan.chan.chan_dev->device,
 			"channel IRQ with no active transfer\n");
 	}
 
@@ -765,7 +765,7 @@ static int jz4780_dma_alloc_chan_resources(struct dma_chan *chan)
 					    JZ_DMA_DESC_BLOCK_SIZE,
 					    PAGE_SIZE, 0);
 	if (!jzchan->desc_pool) {
-		dev_err(&chan->dev->device,
+		dev_err(&chan->chan_dev->device,
 			"failed to allocate descriptor pool\n");
 		return -ENOMEM;
 	}
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 6ffd8bd82154a..c00641366c4dc 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -868,10 +868,10 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name)
 		return chan;
 	chan->slave = dev;
 
-	if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj,
+	if (sysfs_create_link(&chan->chan_dev->device.kobj, &dev->kobj,
 			      DMA_SLAVE_NAME))
 		dev_warn(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
-	if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name))
+	if (sysfs_create_link(&dev->kobj, &chan->chan_dev->device.kobj, chan->name))
 		dev_warn(dev, "Cannot create DMA %s symlink\n", chan->name);
 
 	return chan;
@@ -917,7 +917,7 @@ void dma_release_channel(struct dma_chan *chan)
 	dma_chan_put(chan);
 
 	if (chan->slave) {
-		sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
+		sysfs_remove_link(&chan->chan_dev->device.kobj, DMA_SLAVE_NAME);
 		sysfs_remove_link(&chan->slave->kobj, chan->name);
 		kfree(chan->name);
 		chan->name = NULL;
@@ -1083,8 +1083,8 @@ static int __dma_async_device_channel_register(struct dma_device *device,
 	chan->local = alloc_percpu(typeof(*chan->local));
 	if (!chan->local)
 		return -ENOMEM;
-	chan->dev = kzalloc_obj(*chan->dev);
-	if (!chan->dev) {
+	chan->chan_dev = kzalloc_obj(*chan->chan_dev);
+	if (!chan->chan_dev) {
 		rc = -ENOMEM;
 		goto err_free_local;
 	}
@@ -1101,17 +1101,17 @@ static int __dma_async_device_channel_register(struct dma_device *device,
 		goto err_free_dev;
 	}
 
-	chan->dev->device.class = &dma_devclass;
-	chan->dev->device.parent = device->dev;
-	chan->dev->chan = chan;
-	chan->dev->dev_id = device->dev_id;
+	chan->chan_dev->device.class = &dma_devclass;
+	chan->chan_dev->device.parent = device->dev;
+	chan->chan_dev->chan = chan;
+	chan->chan_dev->dev_id = device->dev_id;
 	spin_lock_init(&chan->lock);
 
 	if (!name)
-		dev_set_name(&chan->dev->device, "dma%dchan%d", device->dev_id, chan->chan_id);
+		dev_set_name(&chan->chan_dev->device, "dma%dchan%d", device->dev_id, chan->chan_id);
 	else
-		dev_set_name(&chan->dev->device, "%s", name);
-	rc = device_register(&chan->dev->device);
+		dev_set_name(&chan->chan_dev->device, "%s", name);
+	rc = device_register(&chan->chan_dev->device);
 	if (rc)
 		goto err_out_ida;
 	chan->client_count = 0;
@@ -1122,7 +1122,7 @@ static int __dma_async_device_channel_register(struct dma_device *device,
  err_out_ida:
 	ida_free(&device->chan_ida, chan->chan_id);
  err_free_dev:
-	kfree(chan->dev);
+	kfree(chan->chan_dev);
  err_free_local:
 	free_percpu(chan->local);
 	chan->local = NULL;
@@ -1155,10 +1155,10 @@ static void __dma_async_device_channel_unregister(struct dma_device *device,
 		  __func__, chan->client_count);
 	mutex_lock(&dma_list_mutex);
 	device->chancnt--;
-	chan->dev->chan = NULL;
+	chan->chan_dev->chan = NULL;
 	mutex_unlock(&dma_list_mutex);
 	ida_free(&device->chan_ida, chan->chan_id);
-	device_unregister(&chan->dev->device);
+	device_unregister(&chan->chan_dev->device);
 	free_percpu(chan->local);
 }
 
@@ -1290,9 +1290,9 @@ int dma_async_device_register(struct dma_device *device)
 		if (chan->local == NULL)
 			continue;
 		mutex_lock(&dma_list_mutex);
-		chan->dev->chan = NULL;
+		chan->chan_dev->chan = NULL;
 		mutex_unlock(&dma_list_mutex);
-		device_unregister(&chan->dev->device);
+		device_unregister(&chan->chan_dev->device);
 		free_percpu(chan->local);
 	}
 	return rc;
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
index 67cc199e24d1f..ccfd09c06807b 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
@@ -121,12 +121,12 @@ struct axi_dma_chan_config {
 
 static inline struct device *dchan2dev(struct dma_chan *dchan)
 {
-	return &dchan->dev->device;
+	return &dchan->chan_dev->device;
 }
 
 static inline struct device *chan2dev(struct axi_dma_chan *chan)
 {
-	return &chan->vc.chan.dev->device;
+	return &chan->vc.chan.chan_dev->device;
 }
 
 static inline struct axi_dma_desc *vd_to_axi_desc(struct virt_dma_desc *vd)
diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index dd75f97a33b3d..d5618c128121f 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -43,7 +43,7 @@
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 static struct dw_desc *dwc_first_active(struct dw_dma_chan *dwc)
diff --git a/drivers/dma/ep93xx_dma.c b/drivers/dma/ep93xx_dma.c
index 311e55a97ba9f..977ab12c793e9 100644
--- a/drivers/dma/ep93xx_dma.c
+++ b/drivers/dma/ep93xx_dma.c
@@ -252,7 +252,7 @@ struct ep93xx_edma_data {
 
 static inline struct device *chan2dev(struct ep93xx_dma_chan *edmac)
 {
-	return &edmac->chan.dev->device;
+	return &edmac->chan.chan_dev->device;
 }
 
 static struct ep93xx_dma_chan *to_ep93xx_dma_chan(struct dma_chan *chan)
diff --git a/drivers/dma/idma64.c b/drivers/dma/idma64.c
index 6399fd5408be2..6fdc0d50964ad 100644
--- a/drivers/dma/idma64.c
+++ b/drivers/dma/idma64.c
@@ -27,7 +27,7 @@
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 /* ---------------------------------------------------------------------- */
diff --git a/drivers/dma/loongson/loongson1-apb-dma.c b/drivers/dma/loongson/loongson1-apb-dma.c
index 89786cbd20ab5..03c8081e4b9a9 100644
--- a/drivers/dma/loongson/loongson1-apb-dma.c
+++ b/drivers/dma/loongson/loongson1-apb-dma.c
@@ -91,7 +91,7 @@ static irqreturn_t ls1x_dma_irq_handler(int irq, void *data);
 
 static inline struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 static inline int ls1x_dma_query(struct ls1x_dma_chan *chan,
diff --git a/drivers/dma/loongson/loongson2-apb-cmc-dma.c b/drivers/dma/loongson/loongson2-apb-cmc-dma.c
index f53f24b7f8ffe..dbb85b72003e1 100644
--- a/drivers/dma/loongson/loongson2-apb-cmc-dma.c
+++ b/drivers/dma/loongson/loongson2-apb-cmc-dma.c
@@ -136,7 +136,7 @@ static struct loongson2_cmc_dma_desc *to_lmdma_desc(struct virt_dma_desc *vdesc)
 
 static struct device *chan2dev(struct loongson2_cmc_dma_chan *lchan)
 {
-	return &lchan->vchan.chan.dev->device;
+	return &lchan->vchan.chan.chan_dev->device;
 }
 
 static u32 loongson2_cmc_dma_read(struct loongson2_cmc_dma_dev *lddev, u32 reg, u32 id)
diff --git a/drivers/dma/loongson/loongson2-apb-dma.c b/drivers/dma/loongson/loongson2-apb-dma.c
index 7c3d7c3273955..94f4364fbfb56 100644
--- a/drivers/dma/loongson/loongson2-apb-dma.c
+++ b/drivers/dma/loongson/loongson2-apb-dma.c
@@ -163,7 +163,7 @@ static inline struct ls2x_dma_priv *to_ldma_priv(struct dma_device *ddev)
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 static void ls2x_dma_desc_free(struct virt_dma_desc *vdesc)
diff --git a/drivers/dma/nbpfaxi.c b/drivers/dma/nbpfaxi.c
index 05d7321629cc8..4dd87cafc5e0a 100644
--- a/drivers/dma/nbpfaxi.c
+++ b/drivers/dma/nbpfaxi.c
@@ -1202,7 +1202,7 @@ static irqreturn_t nbpf_chan_irq(int irq, void *dev)
 
 	nbpf_status_ack(chan);
 
-	dev_dbg(&chan->dma_chan.dev->device, "%s()\n", __func__);
+	dev_dbg(&chan->dma_chan.chan_dev->device, "%s()\n", __func__);
 
 	spin_lock(&chan->lock);
 	desc = chan->running;
diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
index 7c80572fc71d1..ab7531a3a89c9 100644
--- a/drivers/dma/owl-dma.c
+++ b/drivers/dma/owl-dma.c
@@ -294,7 +294,7 @@ static inline struct owl_dma *to_owl_dma(struct dma_device *dd)
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 static inline struct owl_dma_vchan *to_owl_vchan(struct dma_chan *chan)
diff --git a/drivers/dma/pch_dma.c b/drivers/dma/pch_dma.c
index bf805f1024f64..69d60b587c2bb 100644
--- a/drivers/dma/pch_dma.c
+++ b/drivers/dma/pch_dma.c
@@ -152,7 +152,7 @@ static inline struct pch_dma *to_pd(struct dma_device *ddev)
 
 static inline struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 static inline
diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index fa2ee0b3e09f8..5398b47fec370 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -149,7 +149,7 @@ struct pxad_device {
 	({								\
 		u32 _v;							\
 		_v = readl_relaxed((phy)->base + _reg((phy)->idx));	\
-		dev_vdbg(&phy->vchan->vc.chan.dev->device,		\
+		dev_vdbg(&phy->vchan->vc.chan.chan_dev->device,		\
 			 "%s(): readl(%s): 0x%08x\n", __func__, #_reg,	\
 			  _v);						\
 		_v;							\
@@ -157,14 +157,14 @@ struct pxad_device {
 #define phy_writel(phy, val, _reg)					\
 	do {								\
 		writel((val), (phy)->base + _reg((phy)->idx));		\
-		dev_vdbg(&phy->vchan->vc.chan.dev->device,		\
+		dev_vdbg(&phy->vchan->vc.chan.chan_dev->device,		\
 			 "%s(): writel(0x%08x, %s)\n",			\
 			 __func__, (u32)(val), #_reg);			\
 	} while (0)
 #define phy_writel_relaxed(phy, val, _reg)				\
 	do {								\
 		writel_relaxed((val), (phy)->base + _reg((phy)->idx));	\
-		dev_vdbg(&phy->vchan->vc.chan.dev->device,		\
+		dev_vdbg(&phy->vchan->vc.chan.chan_dev->device,		\
 			 "%s(): writel_relaxed(0x%08x, %s)\n",		\
 			 __func__, (u32)(val), #_reg);			\
 	} while (0)
@@ -396,7 +396,7 @@ static struct pxad_phy *lookup_phy(struct pxad_chan *pchan)
 
 out_unlock:
 	spin_unlock_irqrestore(&pdev->phy_lock, flags);
-	dev_dbg(&pchan->vc.chan.dev->device,
+	dev_dbg(&pchan->vc.chan.chan_dev->device,
 		"%s(): phy=%p(%d)\n", __func__, found,
 		found ? found->idx : -1);
 
@@ -409,7 +409,7 @@ static void pxad_free_phy(struct pxad_chan *chan)
 	unsigned long flags;
 	u32 reg;
 
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): freeing\n", __func__);
 	if (!chan->phy)
 		return;
@@ -454,7 +454,7 @@ static void phy_enable(struct pxad_phy *phy, bool misaligned)
 	if (!phy->vchan)
 		return;
 
-	dev_dbg(&phy->vchan->vc.chan.dev->device,
+	dev_dbg(&phy->vchan->vc.chan.chan_dev->device,
 		"%s(); phy=%p(%d) misaligned=%d\n", __func__,
 		phy, phy->idx, misaligned);
 
@@ -483,7 +483,7 @@ static void phy_disable(struct pxad_phy *phy)
 		return;
 
 	dcsr = phy_readl_relaxed(phy, DCSR);
-	dev_dbg(&phy->vchan->vc.chan.dev->device,
+	dev_dbg(&phy->vchan->vc.chan.chan_dev->device,
 		"%s(): phy=%p(%d)\n", __func__, phy, phy->idx);
 	phy_writel(phy, dcsr & ~PXA_DCSR_RUN & ~PXA_DCSR_STOPIRQEN, DCSR);
 }
@@ -491,12 +491,12 @@ static void phy_disable(struct pxad_phy *phy)
 static void pxad_launch_chan(struct pxad_chan *chan,
 				 struct pxad_desc_sw *desc)
 {
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): desc=%p\n", __func__, desc);
 	if (!chan->phy) {
 		chan->phy = lookup_phy(chan);
 		if (!chan->phy) {
-			dev_dbg(&chan->vc.chan.dev->device,
+			dev_dbg(&chan->vc.chan.chan_dev->device,
 				"%s(): no free dma channel\n", __func__);
 			return;
 		}
@@ -592,7 +592,7 @@ static unsigned int clear_chan_irq(struct pxad_phy *phy)
 	dcsr = phy_readl_relaxed(phy, DCSR);
 	phy_writel(phy, dcsr, DCSR);
 	if ((dcsr & PXA_DCSR_BUSERR) && (phy->vchan))
-		dev_warn(&phy->vchan->vc.chan.dev->device,
+		dev_warn(&phy->vchan->vc.chan.chan_dev->device,
 			 "%s(chan=%p): PXA_DCSR_BUSERR\n",
 			 __func__, &phy->vchan);
 
@@ -617,7 +617,7 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id)
 	spin_lock(&chan->vc.lock);
 	list_for_each_entry_safe(vd, tmp, &chan->vc.desc_issued, node) {
 		vd_completed = is_desc_completed(vd);
-		dev_dbg(&chan->vc.chan.dev->device,
+		dev_dbg(&chan->vc.chan.chan_dev->device,
 			"%s(): checking txd %p[%x]: completed=%d dcsr=0x%x\n",
 			__func__, vd, vd->tx.cookie, vd_completed,
 			dcsr);
@@ -640,7 +640,7 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id)
 	}
 
 	if (!chan->bus_error && dcsr & PXA_DCSR_STOPSTATE) {
-		dev_dbg(&chan->vc.chan.dev->device,
+		dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): channel stopped, submitted_empty=%d issued_empty=%d",
 			__func__,
 			list_empty(&chan->vc.desc_submitted),
@@ -694,7 +694,7 @@ static int pxad_alloc_chan_resources(struct dma_chan *dchan)
 					  __alignof__(struct pxad_desc_hw),
 					  0);
 	if (!chan->desc_pool) {
-		dev_err(&chan->vc.chan.dev->device,
+		dev_err(&chan->vc.chan.chan_dev->device,
 			"%s(): unable to allocate descriptor pool\n",
 			__func__);
 		return -ENOMEM;
@@ -749,7 +749,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc)
 	for (i = 0; i < nb_hw_desc; i++) {
 		desc = dma_pool_alloc(sw_desc->desc_pool, GFP_NOWAIT, &dma);
 		if (!desc) {
-			dev_err(&chan->vc.chan.dev->device,
+			dev_err(&chan->vc.chan.chan_dev->device,
 				"%s(): Couldn't allocate the %dth hw_desc from dma_pool %p\n",
 				__func__, i, sw_desc->desc_pool);
 			goto err;
@@ -786,7 +786,7 @@ static dma_cookie_t pxad_tx_submit(struct dma_async_tx_descriptor *tx)
 
 	if (list_empty(&vc->desc_submitted) && pxad_try_hotchain(vc, vd)) {
 		list_move_tail(&vd->node, &vc->desc_issued);
-		dev_dbg(&chan->vc.chan.dev->device,
+		dev_dbg(&chan->vc.chan.chan_dev->device,
 			"%s(): txd %p[%x]: submitted (hot linked)\n",
 			__func__, vd, cookie);
 		goto out;
@@ -809,7 +809,7 @@ static dma_cookie_t pxad_tx_submit(struct dma_async_tx_descriptor *tx)
 		else
 			vd_chained = NULL;
 	}
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): txd %p[%x]: submitted (%s linked)\n",
 		__func__, vd, cookie, vd_chained ? "cold" : "not");
 	list_move_tail(&vd->node, &vc->desc_submitted);
@@ -832,7 +832,7 @@ static void pxad_issue_pending(struct dma_chan *dchan)
 
 	vd_first = list_first_entry(&chan->vc.desc_submitted,
 				    struct virt_dma_desc, node);
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): txd %p[%x]", __func__, vd_first, vd_first->tx.cookie);
 
 	vchan_issue_pending(&chan->vc);
@@ -852,7 +852,7 @@ pxad_tx_prep(struct virt_dma_chan *vc, struct virt_dma_desc *vd,
 	INIT_LIST_HEAD(&vd->node);
 	tx = vchan_tx_prep(vc, vd, tx_flags);
 	tx->tx_submit = pxad_tx_submit;
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): vc=%p txd=%p[%x] flags=0x%lx\n", __func__,
 		vc, vd, vd->tx.cookie,
 		tx_flags);
@@ -891,7 +891,7 @@ static void pxad_get_config(struct pxad_chan *chan,
 		*dcmd |= PXA_DCMD_BURST32 | PXA_DCMD_INCTRGADDR |
 			PXA_DCMD_INCSRCADDR;
 
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): dev_addr=0x%x maxburst=%d width=%d  dir=%d\n",
 		__func__, dev_addr, maxburst, width, dir);
 
@@ -925,7 +925,7 @@ pxad_prep_memcpy(struct dma_chan *dchan,
 	if (!dchan || !len)
 		return NULL;
 
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): dma_dst=0x%lx dma_src=0x%lx len=%zu flags=%lx\n",
 		__func__, (unsigned long)dma_dst, (unsigned long)dma_src,
 		len, flags);
@@ -974,7 +974,7 @@ pxad_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl,
 		return NULL;
 
 	pxad_get_config(chan, dir, &dcmd, &dsadr, &dtadr);
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): dir=%d flags=%lx\n", __func__, dir, flags);
 
 	nb_desc = sg_nents_for_dma(sgl, sg_len, PDMA_MAX_DESC_BYTES);
@@ -1021,7 +1021,7 @@ pxad_prep_dma_cyclic(struct dma_chan *dchan,
 	if (!dchan || !len || !period_len)
 		return NULL;
 	if ((dir != DMA_DEV_TO_MEM) && (dir != DMA_MEM_TO_DEV)) {
-		dev_err(&chan->vc.chan.dev->device,
+		dev_err(&chan->vc.chan.chan_dev->device,
 			"Unsupported direction for cyclic DMA\n");
 		return NULL;
 	}
@@ -1032,7 +1032,7 @@ pxad_prep_dma_cyclic(struct dma_chan *dchan,
 
 	pxad_get_config(chan, dir, &dcmd, &dsadr, &dtadr);
 	dcmd |= PXA_DCMD_ENDIRQEN | (PXA_DCMD_LENGTH & period_len);
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): buf_addr=0x%lx len=%zu period=%zu dir=%d flags=%lx\n",
 		__func__, (unsigned long)buf_addr, len, period_len, dir, flags);
 
@@ -1080,14 +1080,14 @@ static int pxad_terminate_all(struct dma_chan *dchan)
 	struct pxad_phy *phy;
 	LIST_HEAD(head);
 
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): vchan %p: terminate all\n", __func__, &chan->vc);
 
 	spin_lock_irqsave(&chan->vc.lock, flags);
 	vchan_get_all_descriptors(&chan->vc, &head);
 
 	list_for_each_entry(vd, &head, node) {
-		dev_dbg(&chan->vc.chan.dev->device,
+		dev_dbg(&chan->vc.chan.chan_dev->device,
 			"%s(): cancelling txd %p[%x] (completed=%d)", __func__,
 			vd, vd->tx.cookie, is_desc_completed(vd));
 	}
@@ -1177,7 +1177,7 @@ static unsigned int pxad_residue(struct pxad_chan *chan,
 
 out:
 	spin_unlock_irqrestore(&chan->vc.lock, flags);
-	dev_dbg(&chan->vc.chan.dev->device,
+	dev_dbg(&chan->vc.chan.chan_dev->device,
 		"%s(): txd %p[%x] sw_desc=%p: %d\n",
 		__func__, vd, cookie, sw_desc, residue);
 	return residue;
diff --git a/drivers/dma/stm32/stm32-dma.c b/drivers/dma/stm32/stm32-dma.c
index 4e3ecb6763036..5fceed6fd8265 100644
--- a/drivers/dma/stm32/stm32-dma.c
+++ b/drivers/dma/stm32/stm32-dma.c
@@ -250,7 +250,7 @@ static struct stm32_dma_desc *to_stm32_dma_desc(struct virt_dma_desc *vdesc)
 
 static struct device *chan2dev(struct stm32_dma_chan *chan)
 {
-	return &chan->vchan.chan.dev->device;
+	return &chan->vchan.chan.chan_dev->device;
 }
 
 static u32 stm32_dma_read(struct stm32_dma_device *dmadev, u32 reg)
diff --git a/drivers/dma/stm32/stm32-dma3.c b/drivers/dma/stm32/stm32-dma3.c
index ab0fb05597363..81db3b33cabf6 100644
--- a/drivers/dma/stm32/stm32-dma3.c
+++ b/drivers/dma/stm32/stm32-dma3.c
@@ -330,7 +330,7 @@ static inline struct stm32_dma3_swdesc *to_stm32_dma3_swdesc(struct virt_dma_des
 
 static struct device *chan2dev(struct stm32_dma3_chan *chan)
 {
-	return &chan->vchan.chan.dev->device;
+	return &chan->vchan.chan.chan_dev->device;
 }
 
 static struct device *ddata2dev(struct stm32_dma3_ddata *ddata)
diff --git a/drivers/dma/stm32/stm32-mdma.c b/drivers/dma/stm32/stm32-mdma.c
index c274638e919c2..a7ab77e4ebbcb 100644
--- a/drivers/dma/stm32/stm32-mdma.c
+++ b/drivers/dma/stm32/stm32-mdma.c
@@ -278,7 +278,7 @@ static struct stm32_mdma_desc *to_stm32_mdma_desc(struct virt_dma_desc *vdesc)
 
 static struct device *chan2dev(struct stm32_mdma_chan *chan)
 {
-	return &chan->vchan.chan.dev->device;
+	return &chan->vchan.chan.chan_dev->device;
 }
 
 static struct device *mdma2dev(struct stm32_mdma_device *mdma_dev)
diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index f47a326dd7ffa..0fa640557fb07 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -215,7 +215,7 @@ struct sun6i_dma_dev {
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 
 static inline struct sun6i_dma_dev *to_sun6i_dma_dev(struct dma_device *d)
diff --git a/drivers/dma/switchtec_dma.c b/drivers/dma/switchtec_dma.c
index c133535d37656..ebb734f807a3b 100644
--- a/drivers/dma/switchtec_dma.c
+++ b/drivers/dma/switchtec_dma.c
@@ -406,7 +406,7 @@ static int disable_channel(struct switchtec_dma_chan *swdma_chan)
 static void
 switchtec_dma_cleanup_completed(struct switchtec_dma_chan *swdma_chan)
 {
-	struct device *chan_dev = &swdma_chan->dma_chan.dev->device;
+	struct device *chan_dev = &swdma_chan->dma_chan.chan_dev->device;
 	struct switchtec_dma_desc *desc;
 	struct switchtec_dma_hw_ce *ce;
 	struct dmaengine_result res;
@@ -851,7 +851,7 @@ static irqreturn_t switchtec_dma_chan_status_isr(int irq, void *dma)
 	list_for_each_entry(chan, &dma_dev->channels, device_node) {
 		swdma_chan = container_of(chan, struct switchtec_dma_chan,
 					  dma_chan);
-		chan_dev = &swdma_chan->dma_chan.dev->device;
+		chan_dev = &swdma_chan->dma_chan.chan_dev->device;
 		chan_hw = swdma_chan->mmio_chan_hw;
 
 		rcu_read_lock();
@@ -1009,19 +1009,19 @@ static int switchtec_dma_alloc_chan_resources(struct dma_chan *chan)
 	perf_cfg = readl(&swdma_chan->mmio_chan_fw->perf_cfg);
 	rcu_read_unlock();
 
-	dev_dbg(&chan->dev->device, "Burst Size:  0x%x\n",
+	dev_dbg(&chan->chan_dev->device, "Burst Size:  0x%x\n",
 		FIELD_GET(PERF_BURST_SIZE_MASK, perf_cfg));
 
-	dev_dbg(&chan->dev->device, "Burst Scale: 0x%x\n",
+	dev_dbg(&chan->chan_dev->device, "Burst Scale: 0x%x\n",
 		FIELD_GET(PERF_BURST_SCALE_MASK, perf_cfg));
 
-	dev_dbg(&chan->dev->device, "Interval:    0x%x\n",
+	dev_dbg(&chan->chan_dev->device, "Interval:    0x%x\n",
 		FIELD_GET(PERF_INTERVAL_MASK, perf_cfg));
 
-	dev_dbg(&chan->dev->device, "Arb Weight:  0x%x\n",
+	dev_dbg(&chan->chan_dev->device, "Arb Weight:  0x%x\n",
 		FIELD_GET(PERF_ARB_WEIGHT_MASK, perf_cfg));
 
-	dev_dbg(&chan->dev->device, "MRRS:        0x%x\n",
+	dev_dbg(&chan->chan_dev->device, "MRRS:        0x%x\n",
 		FIELD_GET(PERF_MRRS_MASK, perf_cfg));
 
 	return SWITCHTEC_DMA_SQ_SIZE;
diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
index 64cedef1050ae..e36111e8a76dc 100644
--- a/drivers/dma/tegra186-gpc-dma.c
+++ b/drivers/dma/tegra186-gpc-dma.c
@@ -1537,7 +1537,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	 * the channels available and registered for the DMA device are used.
 	 */
 	list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
-		chdev = &chan->dev->device;
+		chdev = &chan->chan_dev->device;
 		tdc = to_tegra_dma_chan(chan);
 
 		if (use_iommu_map) {
@@ -1554,7 +1554,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 				return dev_err_probe(chdev, -EINVAL,
 					   "Failed to get stream ID for channel %d\n", tdc->id);
 
-			chan->dev->chan_dma_dev = true;
+			chan->chan_dev->chan_dma_dev = true;
 		}
 
 		/* program stream-id for this channel */
diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 640b8a218c9ad..33811e7ee6552 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -256,7 +256,7 @@ txd_to_tegra_dma_desc(struct dma_async_tx_descriptor *td)
 
 static inline struct device *tdc2dev(struct tegra_dma_channel *tdc)
 {
-	return &tdc->dma_chan.dev->device;
+	return &tdc->dma_chan.chan_dev->device;
 }
 
 static dma_cookie_t tegra_dma_tx_submit(struct dma_async_tx_descriptor *tx);
diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
index fb21e0df5ab7b..4fa6e81ff5a86 100644
--- a/drivers/dma/ti/k3-udma.c
+++ b/drivers/dma/ti/k3-udma.c
@@ -422,16 +422,16 @@ static int navss_psil_unpair(struct udma_dev *ud, u32 src_thread,
 
 static void k3_configure_chan_coherency(struct dma_chan *chan, u32 asel)
 {
-	struct device *chan_dev = &chan->dev->device;
+	struct device *chan_dev = &chan->chan_dev->device;
 
 	if (asel == 0) {
 		/* No special handling for the channel */
-		chan->dev->chan_dma_dev = false;
+		chan->chan_dev->chan_dma_dev = false;
 
 		dev_clear_dma_coherent(chan_dev);
 		chan_dev->dma_parms = NULL;
 	} else if (asel == 14 || asel == 15) {
-		chan->dev->chan_dma_dev = true;
+		chan->chan_dev->chan_dma_dev = true;
 
 		dev_set_dma_coherent(chan_dev);
 		dma_coerce_mask_and_coherent(chan_dev, DMA_BIT_MASK(48));
diff --git a/drivers/dma/timb_dma.c b/drivers/dma/timb_dma.c
index 4fc5119854ec1..f414e41d90013 100644
--- a/drivers/dma/timb_dma.c
+++ b/drivers/dma/timb_dma.c
@@ -93,7 +93,7 @@ struct timb_dma {
 
 static struct device *chan2dev(struct dma_chan *chan)
 {
-	return &chan->dev->device;
+	return &chan->chan_dev->device;
 }
 static struct device *chan2dmadev(struct dma_chan *chan)
 {
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index fe33a20abc614..0fcec3f21390b 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -325,7 +325,8 @@ struct dma_router {
  * @lock: protect between config and prepare transfer when driver have not
  *	  implemented callback device_prep_config_sg().
  * @chan_id: channel ID for sysfs
- * @dev: class device for sysfs
+ * @chan_dev: class channel device for sysfs, some device use it for per-channel
+ *            iommu mapping.
  * @name: backlink name for sysfs
  * @dbg_client_name: slave name for debugfs in format:
  *	dev_name(requester's dev):channel name, for example: "2b00000.mcasp:tx"
@@ -351,7 +352,14 @@ struct dma_chan {
 
 	/* sysfs */
 	int chan_id;
-	struct dma_chan_dev *dev;
+	union {
+		struct dma_chan_dev *chan_dev;
+		/*
+		 * please use chan_dev, dev will be removed after all user
+		   switch to chan_dev
+		*/
+		struct dma_chan_dev *dev;
+	};
 	const char *name;
 #ifdef CONFIG_DEBUG_FS
 	char *dbg_client_name;
@@ -532,7 +540,7 @@ struct dma_slave_caps {
 
 static inline const char *dma_chan_name(struct dma_chan *chan)
 {
-	return dev_name(&chan->dev->device);
+	return dev_name(&chan->chan_dev->device);
 }
 
 /**
@@ -1805,8 +1813,8 @@ dmaengine_get_direction_text(enum dma_transfer_direction dir)
 
 static inline struct device *dmaengine_get_dma_device(struct dma_chan *chan)
 {
-	if (chan->dev->chan_dma_dev)
-		return &chan->dev->device;
+	if (chan->chan_dev->chan_dma_dev)
+		return &chan->chan_dev->device;
 
 	return chan->device->dev;
 }

-- 
2.43.0