[PATCH v1 1/9] dmaengine: Actions: get rid of bit fields from dma descriptor

[PATCH v1 1/9] dmaengine: Actions: get rid of bit fields from dma descriptor

[Amit Singh Tomar]

At the moment, Driver uses bit fields to describe registers of the DMA
descriptor structure that makes it less portable and maintainable, and
Andre suugested(and even sketched important bits for it) to make use of
array to describe this DMA descriptors instead. It gives the flexibility
while extending support for other platform such as Actions S700.

This commit removes the "owl_dma_lli_hw" (that includes bit-fields) and
uses array to describe DMA descriptor.

Suggested-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
---
Changes since RFC:
	* No change from RFC.
---
 drivers/dma/owl-dma.c | 77 ++++++++++++++++++++++-----------------------------
 1 file changed, 33 insertions(+), 44 deletions(-)

diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
index c683051257fd..b0d80a2fa383 100644
--- a/drivers/dma/owl-dma.c
+++ b/drivers/dma/owl-dma.c
@@ -120,30 +120,18 @@
 #define BIT_FIELD(val, width, shift, newshift)	\
 		((((val) >> (shift)) & ((BIT(width)) - 1)) << (newshift))
 
-/**
- * struct owl_dma_lli_hw - Hardware link list for dma transfer
- * @next_lli: physical address of the next link list
- * @saddr: source physical address
- * @daddr: destination physical address
- * @flen: frame length
- * @fcnt: frame count
- * @src_stride: source stride
- * @dst_stride: destination stride
- * @ctrla: dma_mode and linklist ctrl config
- * @ctrlb: interrupt config
- * @const_num: data for constant fill
- */
-struct owl_dma_lli_hw {
-	u32	next_lli;
-	u32	saddr;
-	u32	daddr;
-	u32	flen:20;
-	u32	fcnt:12;
-	u32	src_stride;
-	u32	dst_stride;
-	u32	ctrla;
-	u32	ctrlb;
-	u32	const_num;
+/* Describe DMA descriptor, hardware link list for dma transfer */
+enum owl_dmadesc_offsets {
+	OWL_DMADESC_NEXT_LLI = 0,
+	OWL_DMADESC_SADDR,
+	OWL_DMADESC_DADDR,
+	OWL_DMADESC_FLEN,
+	OWL_DMADESC_SRC_STRIDE,
+	OWL_DMADESC_DST_STRIDE,
+	OWL_DMADESC_CTRLA,
+	OWL_DMADESC_CTRLB,
+	OWL_DMADESC_CONST_NUM,
+	OWL_DMADESC_SIZE
 };
 
 /**
@@ -153,7 +141,7 @@ struct owl_dma_lli_hw {
  * @node: node for txd's lli_list
  */
 struct owl_dma_lli {
-	struct  owl_dma_lli_hw	hw;
+	u32			hw[OWL_DMADESC_SIZE];
 	dma_addr_t		phys;
 	struct list_head	node;
 };
@@ -351,8 +339,9 @@ static struct owl_dma_lli *owl_dma_add_lli(struct owl_dma_txd *txd,
 		list_add_tail(&next->node, &txd->lli_list);
 
 	if (prev) {
-		prev->hw.next_lli = next->phys;
-		prev->hw.ctrla |= llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
+		prev->hw[OWL_DMADESC_NEXT_LLI] = next->phys;
+		prev->hw[OWL_DMADESC_CTRLA] |=
+					llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
 	}
 
 	return next;
@@ -365,8 +354,7 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 				  struct dma_slave_config *sconfig,
 				  bool is_cyclic)
 {
-	struct owl_dma_lli_hw *hw = &lli->hw;
-	u32 mode;
+	u32 mode, ctrlb;
 
 	mode = OWL_DMA_MODE_PW(0);
 
@@ -407,22 +395,22 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 		return -EINVAL;
 	}
 
-	hw->next_lli = 0; /* One link list by default */
-	hw->saddr = src;
-	hw->daddr = dst;
-
-	hw->fcnt = 1; /* Frame count fixed as 1 */
-	hw->flen = len; /* Max frame length is 1MB */
-	hw->src_stride = 0;
-	hw->dst_stride = 0;
-	hw->ctrla = llc_hw_ctrla(mode,
-				 OWL_DMA_LLC_SAV_LOAD_NEXT |
-				 OWL_DMA_LLC_DAV_LOAD_NEXT);
+	lli->hw[OWL_DMADESC_CTRLA] = llc_hw_ctrla(mode,
+						  OWL_DMA_LLC_SAV_LOAD_NEXT |
+						  OWL_DMA_LLC_DAV_LOAD_NEXT);
 
 	if (is_cyclic)
-		hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
+		ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
 	else
-		hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
+		ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
+
+	lli->hw[OWL_DMADESC_NEXT_LLI] = 0;
+	lli->hw[OWL_DMADESC_SADDR] = src;
+	lli->hw[OWL_DMADESC_DADDR] = dst;
+	lli->hw[OWL_DMADESC_SRC_STRIDE] = 0;
+	lli->hw[OWL_DMADESC_DST_STRIDE] = 0;
+	lli->hw[OWL_DMADESC_FLEN] = len | 1 << 20;
+	lli->hw[OWL_DMADESC_CTRLB] = ctrlb;
 
 	return 0;
 }
@@ -754,7 +742,8 @@ static u32 owl_dma_getbytes_chan(struct owl_dma_vchan *vchan)
 			/* Start from the next active node */
 			if (lli->phys == next_lli_phy) {
 				list_for_each_entry(lli, &txd->lli_list, node)
-					bytes += lli->hw.flen;
+					bytes += lli->hw[OWL_DMADESC_FLEN] &
+						 GENMASK(19, 0);
 				break;
 			}
 		}
@@ -785,7 +774,7 @@ static enum dma_status owl_dma_tx_status(struct dma_chan *chan,
 	if (vd) {
 		txd = to_owl_txd(&vd->tx);
 		list_for_each_entry(lli, &txd->lli_list, node)
-			bytes += lli->hw.flen;
+			bytes += lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
 	} else {
 		bytes = owl_dma_getbytes_chan(vchan);
 	}
-- 
2.7.4

Re: [PATCH v1 1/9] dmaengine: Actions: get rid of bit fields from dma descriptor

[Vinod Koul]

On 14-05-20, 21:40, Amit Singh Tomar wrote:
> At the moment, Driver uses bit fields to describe registers of the DMA
> descriptor structure that makes it less portable and maintainable, and
> Andre suugested(and even sketched important bits for it) to make use of
> array to describe this DMA descriptors instead. It gives the flexibility
> while extending support for other platform such as Actions S700.
> 
> This commit removes the "owl_dma_lli_hw" (that includes bit-fields) and
> uses array to describe DMA descriptor.

So i see patch 1/9 and 2/9 in my inbox... where are the rest ? No cover
to detail out what the rest contains, who should merge them etc etc!

If you are sending a series to different subsystem please make a habit
to CC everyone on cover letter so that we understand details about the
series. If not dependent, just send as individual units to subsystems!

-- 
~Vinod

Re: [PATCH v1 1/9] dmaengine: Actions: get rid of bit fields from dma descriptor

[Amit Tomer]

Hi,

On Thu, May 14, 2020 at 11:58 PM Vinod Koul <vkoul@kernel.org> wrote:
>
> On 14-05-20, 21:40, Amit Singh Tomar wrote:
> > At the moment, Driver uses bit fields to describe registers of the DMA
> > descriptor structure that makes it less portable and maintainable, and
> > Andre suugested(and even sketched important bits for it) to make use of
> > array to describe this DMA descriptors instead. It gives the flexibility
> > while extending support for other platform such as Actions S700.
> >
> > This commit removes the "owl_dma_lli_hw" (that includes bit-fields) and
> > uses array to describe DMA descriptor.
>
> So i see patch 1/9 and 2/9 in my inbox... where are the rest ? No cover
> to detail out what the rest contains, who should merge them etc etc!
>
> If you are sending a series to different subsystem please make a habit
> to CC everyone on cover letter so that we understand details about the
> series. If not dependent, just send as individual units to subsystems!

Ok, I would make note of it and Cc everyone on cover letter going forward.

Thanks
-Amit

Re: [PATCH v1 1/9] dmaengine: Actions: get rid of bit fields from dma descriptor

[Vinod Koul]

On 15-05-20, 00:04, Amit Tomer wrote:
> Hi,
> 
> On Thu, May 14, 2020 at 11:58 PM Vinod Koul <vkoul@kernel.org> wrote:
> >
> > On 14-05-20, 21:40, Amit Singh Tomar wrote:
> > > At the moment, Driver uses bit fields to describe registers of the DMA
> > > descriptor structure that makes it less portable and maintainable, and
> > > Andre suugested(and even sketched important bits for it) to make use of
> > > array to describe this DMA descriptors instead. It gives the flexibility
> > > while extending support for other platform such as Actions S700.
> > >
> > > This commit removes the "owl_dma_lli_hw" (that includes bit-fields) and
> > > uses array to describe DMA descriptor.
> >
> > So i see patch 1/9 and 2/9 in my inbox... where are the rest ? No cover
> > to detail out what the rest contains, who should merge them etc etc!

and what is the answer for this..?

> >
> > If you are sending a series to different subsystem please make a habit
> > to CC everyone on cover letter so that we understand details about the
> > series. If not dependent, just send as individual units to subsystems!
> 
> Ok, I would make note of it and Cc everyone on cover letter going forward.
> 
> Thanks
> -Amit

-- 
~Vinod

Re: [PATCH v1 1/9] dmaengine: Actions: get rid of bit fields from dma descriptor

[Amit Tomer]

Hi

> > > So i see patch 1/9 and 2/9 in my inbox... where are the rest ? No cover
> > > to detail out what the rest contains, who should merge them etc etc!
>
> and what is the answer for this..?

I do have a cover letter for this series , But CCed only to Actions
Semi SoC maintainers
and mailing list.

Also, As I said going forward I would Cc every stake holder at least
for cover letter.

Thanks
-Amit

Re: [PATCH v1 1/9] dmaengine: Actions: get rid of bit fields from dma descriptor

[Amit Tomer]

Hi,

> I do have a cover letter for this series , But CCed only to Actions
> Semi SoC maintainers
> and mailing list.

and following is the link to cover letter for v1:

http://lists.infradead.org/pipermail/linux-arm-kernel/2020-May/732075.html

Thanks
-Amit

[PATCH v1 2/9] dmaengine: Actions: Add support for S700 DMA engine

[Amit Singh Tomar]

DMA controller present on S700 SoC is compatible with the one on S900
(as most of registers are same), but it has different DMA descriptor
structure where registers "fcnt" and "ctrlb" uses different encoding.

For instance, on S900 "fcnt" starts at offset 0x0c and uses upper 12
bits whereas on S700, it starts at offset 0x1c and uses lower 12 bits.

This commit adds support for DMA controller present on S700.

Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
---
Changes since RFC:
	* Added accessor function to get the frame lenght.
	* Removed the SoC specific check in IRQ routine.
---
 drivers/dma/owl-dma.c | 50 +++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 37 insertions(+), 13 deletions(-)

diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
index b0d80a2fa383..afa6c6f43d26 100644
--- a/drivers/dma/owl-dma.c
+++ b/drivers/dma/owl-dma.c
@@ -134,6 +134,11 @@ enum owl_dmadesc_offsets {
 	OWL_DMADESC_SIZE
 };
 
+enum owl_dma_id {
+	S900_DMA,
+	S700_DMA,
+};
+
 /**
  * struct owl_dma_lli - Link list for dma transfer
  * @hw: hardware link list
@@ -200,6 +205,7 @@ struct owl_dma_vchan {
  * @pchans: array of data for the physical channels
  * @nr_vchans: the number of physical channels
  * @vchans: array of data for the physical channels
+ * @devid: device id based on OWL SoC
  */
 struct owl_dma {
 	struct dma_device	dma;
@@ -214,6 +220,7 @@ struct owl_dma {
 
 	unsigned int		nr_vchans;
 	struct owl_dma_vchan	*vchans;
+	enum owl_dma_id		devid;
 };
 
 static void pchan_update(struct owl_dma_pchan *pchan, u32 reg,
@@ -308,6 +315,11 @@ static inline u32 llc_hw_ctrlb(u32 int_ctl)
 	return ctl;
 }
 
+static inline u32 llc_hw_flen(struct owl_dma_lli *lli)
+{
+	return lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
+}
+
 static void owl_dma_free_lli(struct owl_dma *od,
 			     struct owl_dma_lli *lli)
 {
@@ -354,6 +366,7 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 				  struct dma_slave_config *sconfig,
 				  bool is_cyclic)
 {
+	struct owl_dma *od = to_owl_dma(vchan->vc.chan.device);
 	u32 mode, ctrlb;
 
 	mode = OWL_DMA_MODE_PW(0);
@@ -409,8 +422,14 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 	lli->hw[OWL_DMADESC_DADDR] = dst;
 	lli->hw[OWL_DMADESC_SRC_STRIDE] = 0;
 	lli->hw[OWL_DMADESC_DST_STRIDE] = 0;
-	lli->hw[OWL_DMADESC_FLEN] = len | 1 << 20;
-	lli->hw[OWL_DMADESC_CTRLB] = ctrlb;
+
+	if (od->devid == S700_DMA) {
+		lli->hw[OWL_DMADESC_FLEN] = len;
+		lli->hw[OWL_DMADESC_CTRLB] = 1 | ctrlb;
+	} else {
+		lli->hw[OWL_DMADESC_FLEN] = len | 1 << 20;
+		lli->hw[OWL_DMADESC_CTRLB] = ctrlb;
+	}
 
 	return 0;
 }
@@ -572,7 +591,7 @@ static irqreturn_t owl_dma_interrupt(int irq, void *dev_id)
 
 		global_irq_pending = dma_readl(od, OWL_DMA_IRQ_PD0);
 
-		if (chan_irq_pending && !(global_irq_pending & BIT(i)))	{
+		if (chan_irq_pending && !(global_irq_pending & BIT(i))) {
 			dev_dbg(od->dma.dev,
 				"global and channel IRQ pending match err\n");
 
@@ -741,9 +760,9 @@ static u32 owl_dma_getbytes_chan(struct owl_dma_vchan *vchan)
 		list_for_each_entry(lli, &txd->lli_list, node) {
 			/* Start from the next active node */
 			if (lli->phys == next_lli_phy) {
-				list_for_each_entry(lli, &txd->lli_list, node)
-					bytes += lli->hw[OWL_DMADESC_FLEN] &
-						 GENMASK(19, 0);
+				list_for_each_entry(lli, &txd->lli_list,
+						    node)
+					bytes += llc_hw_flen(lli);
 				break;
 			}
 		}
@@ -774,7 +793,7 @@ static enum dma_status owl_dma_tx_status(struct dma_chan *chan,
 	if (vd) {
 		txd = to_owl_txd(&vd->tx);
 		list_for_each_entry(lli, &txd->lli_list, node)
-			bytes += lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
+			bytes += llc_hw_flen(lli);
 	} else {
 		bytes = owl_dma_getbytes_chan(vchan);
 	}
@@ -1031,11 +1050,20 @@ static struct dma_chan *owl_dma_of_xlate(struct of_phandle_args *dma_spec,
 	return chan;
 }
 
+static const struct of_device_id owl_dma_match[] = {
+	{ .compatible = "actions,s900-dma", .data = (void *)S900_DMA,},
+	{ .compatible = "actions,s700-dma", .data = (void *)S700_DMA,},
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, owl_dma_match);
+
 static int owl_dma_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct owl_dma *od;
 	int ret, i, nr_channels, nr_requests;
+	const struct of_device_id *of_id =
+				of_match_device(owl_dma_match, &pdev->dev);
 
 	od = devm_kzalloc(&pdev->dev, sizeof(*od), GFP_KERNEL);
 	if (!od)
@@ -1060,6 +1088,8 @@ static int owl_dma_probe(struct platform_device *pdev)
 	dev_info(&pdev->dev, "dma-channels %d, dma-requests %d\n",
 		 nr_channels, nr_requests);
 
+	od->devid = (enum owl_dma_id)of_id->data;
+
 	od->nr_pchans = nr_channels;
 	od->nr_vchans = nr_requests;
 
@@ -1192,12 +1222,6 @@ static int owl_dma_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static const struct of_device_id owl_dma_match[] = {
-	{ .compatible = "actions,s900-dma", },
-	{ /* sentinel */ }
-};
-MODULE_DEVICE_TABLE(of, owl_dma_match);
-
 static struct platform_driver owl_dma_driver = {
 	.probe	= owl_dma_probe,
 	.remove	= owl_dma_remove,
-- 
2.7.4

Re: [PATCH v1 2/9] dmaengine: Actions: Add support for S700 DMA engine

[André Przywara]

On 14/05/2020 17:10, Amit Singh Tomar wrote:

Hi,

> DMA controller present on S700 SoC is compatible with the one on S900
> (as most of registers are same), but it has different DMA descriptor
> structure where registers "fcnt" and "ctrlb" uses different encoding.
> 
> For instance, on S900 "fcnt" starts at offset 0x0c and uses upper 12
> bits whereas on S700, it starts at offset 0x1c and uses lower 12 bits.
> 
> This commit adds support for DMA controller present on S700.
> 
> Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
> ---
> Changes since RFC:
> 	* Added accessor function to get the frame lenght.
> 	* Removed the SoC specific check in IRQ routine.
> ---
>  drivers/dma/owl-dma.c | 50 +++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 37 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
> index b0d80a2fa383..afa6c6f43d26 100644
> --- a/drivers/dma/owl-dma.c
> +++ b/drivers/dma/owl-dma.c
> @@ -134,6 +134,11 @@ enum owl_dmadesc_offsets {
>  	OWL_DMADESC_SIZE
>  };
>  
> +enum owl_dma_id {
> +	S900_DMA,
> +	S700_DMA,
> +};
> +
>  /**
>   * struct owl_dma_lli - Link list for dma transfer
>   * @hw: hardware link list
> @@ -200,6 +205,7 @@ struct owl_dma_vchan {
>   * @pchans: array of data for the physical channels
>   * @nr_vchans: the number of physical channels
>   * @vchans: array of data for the physical channels
> + * @devid: device id based on OWL SoC
>   */
>  struct owl_dma {
>  	struct dma_device	dma;
> @@ -214,6 +220,7 @@ struct owl_dma {
>  
>  	unsigned int		nr_vchans;
>  	struct owl_dma_vchan	*vchans;
> +	enum owl_dma_id		devid;
>  };
>  
>  static void pchan_update(struct owl_dma_pchan *pchan, u32 reg,
> @@ -308,6 +315,11 @@ static inline u32 llc_hw_ctrlb(u32 int_ctl)
>  	return ctl;
>  }
>  
> +static inline u32 llc_hw_flen(struct owl_dma_lli *lli)

Drop the inline, that's not needed. The compiler knows better.

> +{
> +	return lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
> +}

Please introduce this function in the previous patch already. Otherwise
you replace code here that you introduced only there.

> +
>  static void owl_dma_free_lli(struct owl_dma *od,
>  			     struct owl_dma_lli *lli)
>  {
> @@ -354,6 +366,7 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
>  				  struct dma_slave_config *sconfig,
>  				  bool is_cyclic)
>  {
> +	struct owl_dma *od = to_owl_dma(vchan->vc.chan.device);
>  	u32 mode, ctrlb;
>  
>  	mode = OWL_DMA_MODE_PW(0);
> @@ -409,8 +422,14 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
>  	lli->hw[OWL_DMADESC_DADDR] = dst;
>  	lli->hw[OWL_DMADESC_SRC_STRIDE] = 0;
>  	lli->hw[OWL_DMADESC_DST_STRIDE] = 0;
> -	lli->hw[OWL_DMADESC_FLEN] = len | 1 << 20;
> -	lli->hw[OWL_DMADESC_CTRLB] = ctrlb;
> +
> +	if (od->devid == S700_DMA) {
> +		lli->hw[OWL_DMADESC_FLEN] = len;
> +		lli->hw[OWL_DMADESC_CTRLB] = 1 | ctrlb;
> +	} else {
> +		lli->hw[OWL_DMADESC_FLEN] = len | 1 << 20;
> +		lli->hw[OWL_DMADESC_CTRLB] = ctrlb;

Can you either add comments or use macros to explain what's going on
here? What is the "1" about?

> +	}
>  
>  	return 0;
>  }
> @@ -572,7 +591,7 @@ static irqreturn_t owl_dma_interrupt(int irq, void *dev_id)
>  
>  		global_irq_pending = dma_readl(od, OWL_DMA_IRQ_PD0);
>  
> -		if (chan_irq_pending && !(global_irq_pending & BIT(i)))	{
> +		if (chan_irq_pending && !(global_irq_pending & BIT(i))) {
>  			dev_dbg(od->dma.dev,
>  				"global and channel IRQ pending match err\n");
>  
> @@ -741,9 +760,9 @@ static u32 owl_dma_getbytes_chan(struct owl_dma_vchan *vchan)
>  		list_for_each_entry(lli, &txd->lli_list, node) {
>  			/* Start from the next active node */
>  			if (lli->phys == next_lli_phy) {
> -				list_for_each_entry(lli, &txd->lli_list, node)
> -					bytes += lli->hw[OWL_DMADESC_FLEN] &
> -						 GENMASK(19, 0);
> +				list_for_each_entry(lli, &txd->lli_list,
> +						    node)

Not needed line break?

Cheers,
Andre.


> +					bytes += llc_hw_flen(lli);
>  				break;
>  			}
>  		}
> @@ -774,7 +793,7 @@ static enum dma_status owl_dma_tx_status(struct dma_chan *chan,
>  	if (vd) {
>  		txd = to_owl_txd(&vd->tx);
>  		list_for_each_entry(lli, &txd->lli_list, node)
> -			bytes += lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
> +			bytes += llc_hw_flen(lli);
>  	} else {
>  		bytes = owl_dma_getbytes_chan(vchan);
>  	}
> @@ -1031,11 +1050,20 @@ static struct dma_chan *owl_dma_of_xlate(struct of_phandle_args *dma_spec,
>  	return chan;
>  }
>  
> +static const struct of_device_id owl_dma_match[] = {
> +	{ .compatible = "actions,s900-dma", .data = (void *)S900_DMA,},
> +	{ .compatible = "actions,s700-dma", .data = (void *)S700_DMA,},
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, owl_dma_match);
> +
>  static int owl_dma_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
>  	struct owl_dma *od;
>  	int ret, i, nr_channels, nr_requests;
> +	const struct of_device_id *of_id =
> +				of_match_device(owl_dma_match, &pdev->dev);
>  
>  	od = devm_kzalloc(&pdev->dev, sizeof(*od), GFP_KERNEL);
>  	if (!od)
> @@ -1060,6 +1088,8 @@ static int owl_dma_probe(struct platform_device *pdev)
>  	dev_info(&pdev->dev, "dma-channels %d, dma-requests %d\n",
>  		 nr_channels, nr_requests);
>  
> +	od->devid = (enum owl_dma_id)of_id->data;
> +
>  	od->nr_pchans = nr_channels;
>  	od->nr_vchans = nr_requests;
>  
> @@ -1192,12 +1222,6 @@ static int owl_dma_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -static const struct of_device_id owl_dma_match[] = {
> -	{ .compatible = "actions,s900-dma", },
> -	{ /* sentinel */ }
> -};
> -MODULE_DEVICE_TABLE(of, owl_dma_match);
> -
>  static struct platform_driver owl_dma_driver = {
>  	.probe	= owl_dma_probe,
>  	.remove	= owl_dma_remove,
>