[PATCH v2] of: Make of_dma_get_range() work on bus nodes

[PATCH v2] of: Make of_dma_get_range() work on bus nodes

[Rob Herring]

From: Robin Murphy <robin.murphy@arm.com>

Since the "dma-ranges" property is only valid for a node representing a
bus, of_dma_get_range() currently assumes the node passed in is a leaf
representing a device, and starts the walk from its parent. In cases
like PCI host controllers on typical FDT systems, however, where the PCI
endpoints are probed dynamically the initial leaf node represents the
'bus' itself, and this logic means we fail to consider any "dma-ranges"
describing the host bridge itself. Rework the logic such that
of_dma_get_range() also works correctly starting from a bus node
containing "dma-ranges".

While this does mean "dma-ranges" could incorrectly be in a device leaf
node, there isn't really any way in this function to ensure that a leaf
node is or isn't a bus node.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[robh: Allow for the bus child node to still be passed in]
Signed-off-by: Rob Herring <robh@kernel.org>
---
Resending, hit send too quickly.

v2:
 - Ensure once we find dma-ranges, every parent has it.
 - Only get the #{size,address}-cells after we find non-empty dma-ranges
 - Add a check on the 'dma-ranges' length

This is all that remains of the dma-ranges series. I've applied the rest 
of the series prep and fixes. I dropped "of: Ratify of_dma_configure() 
interface" as the assertions that the node pointer being the parent only 
when struct device doesn't have a DT node pointer is not always 
true.

I didn't include any tested-bys as this has changed a bit. A git branch 
is here[1].

Rob

[1] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git dma-masks-v2

 drivers/of/address.c | 44 ++++++++++++++++++--------------------------
 1 file changed, 18 insertions(+), 26 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 5ce69d026584..99c1b8058559 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -930,47 +930,39 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	const __be32 *ranges = NULL;
 	int len, naddr, nsize, pna;
 	int ret = 0;
+	bool found_dma_ranges = false;
 	u64 dmaaddr;
 
-	if (!node)
-		return -EINVAL;
-
-	while (1) {
-		struct device_node *parent;
-
-		naddr = of_n_addr_cells(node);
-		nsize = of_n_size_cells(node);
-
-		parent = __of_get_dma_parent(node);
-		of_node_put(node);
-
-		node = parent;
-		if (!node)
-			break;
-
+	while (node) {
 		ranges = of_get_property(node, "dma-ranges", &len);
 
 		/* Ignore empty ranges, they imply no translation required */
 		if (ranges && len > 0)
 			break;
 
-		/*
-		 * At least empty ranges has to be defined for parent node if
-		 * DMA is supported
-		 */
-		if (!ranges)
-			break;
+		/* Once we find 'dma-ranges', then a missing one is an error */
+		if (found_dma_ranges && !ranges) {
+			ret = -ENODEV;
+			goto out;
+		}
+		found_dma_ranges = true;
+
+		node = of_get_next_dma_parent(node);
 	}
 
-	if (!ranges) {
+	if (!node || !ranges) {
 		pr_debug("no dma-ranges found for node(%pOF)\n", np);
 		ret = -ENODEV;
 		goto out;
 	}
 
-	len /= sizeof(u32);
-
+	naddr = of_bus_n_addr_cells(node);
+	nsize = of_bus_n_size_cells(node);
 	pna = of_n_addr_cells(node);
+	if ((len / sizeof(__be32)) % (pna + naddr + nsize)) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	/* dma-ranges format:
 	 * DMA addr	: naddr cells
@@ -978,7 +970,7 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	 * size		: nsize cells
 	 */
 	dmaaddr = of_read_number(ranges, naddr);
-	*paddr = of_translate_dma_address(np, ranges);
+	*paddr = of_translate_dma_address(node, ranges + naddr);
 	if (*paddr == OF_BAD_ADDR) {
 		pr_err("translation of DMA address(%llx) to CPU address failed node(%pOF)\n",
 		       dmaaddr, np);
-- 
2.20.1

Re: [PATCH v2] of: Make of_dma_get_range() work on bus nodes

[Nicolas Saenz Julienne]

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Hi Rob/Robin,

On Tue, 2019-10-08 at 14:52 -0500, Rob Herring wrote:
> From: Robin Murphy <robin.murphy@arm.com>
> 
> Since the "dma-ranges" property is only valid for a node representing a
> bus, of_dma_get_range() currently assumes the node passed in is a leaf
> representing a device, and starts the walk from its parent. In cases
> like PCI host controllers on typical FDT systems, however, where the PCI
> endpoints are probed dynamically the initial leaf node represents the
> 'bus' itself, and this logic means we fail to consider any "dma-ranges"
> describing the host bridge itself. Rework the logic such that
> of_dma_get_range() also works correctly starting from a bus node
> containing "dma-ranges".
> 
> While this does mean "dma-ranges" could incorrectly be in a device leaf
> node, there isn't really any way in this function to ensure that a leaf
> node is or isn't a bus node.

Sorry, I'm not totally sure if this is what you're pointing out with the last
sentence. But, what about the case of a bus configuring a device which also
happens to be a memory mapped bus (say a PCI platform device). It'll get it's
dma config based on its own dma-ranges which is not what we want.

> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> [robh: Allow for the bus child node to still be passed in]
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
> Resending, hit send too quickly.
> 
> v2:
>  - Ensure once we find dma-ranges, every parent has it.

I like this new approach.

Regards,
Nicolas

>  - Only get the #{size,address}-cells after we find non-empty dma-ranges
>  - Add a check on the 'dma-ranges' length
> 
> This is all that remains of the dma-ranges series. I've applied the rest 
> of the series prep and fixes. I dropped "of: Ratify of_dma_configure() 
> interface" as the assertions that the node pointer being the parent only 
> when struct device doesn't have a DT node pointer is not always 
> true.
> 
> I didn't include any tested-bys as this has changed a bit. A git branch 
> is here[1].
> 
> Rob
> 
> [1] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git dma-masks-v2
> 
>  drivers/of/address.c | 44 ++++++++++++++++++--------------------------
>  1 file changed, 18 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 5ce69d026584..99c1b8058559 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -930,47 +930,39 @@ int of_dma_get_range(struct device_node *np, u64
> *dma_addr, u64 *paddr, u64 *siz
>  	const __be32 *ranges = NULL;
>  	int len, naddr, nsize, pna;
>  	int ret = 0;
> +	bool found_dma_ranges = false;
>  	u64 dmaaddr;
>  
> -	if (!node)
> -		return -EINVAL;
> -
> -	while (1) {
> -		struct device_node *parent;
> -
> -		naddr = of_n_addr_cells(node);
> -		nsize = of_n_size_cells(node);
> -
> -		parent = __of_get_dma_parent(node);
> -		of_node_put(node);
> -
> -		node = parent;
> -		if (!node)
> -			break;
> -
> +	while (node) {
>  		ranges = of_get_property(node, "dma-ranges", &len);
>  
>  		/* Ignore empty ranges, they imply no translation required */
>  		if (ranges && len > 0)
>  			break;
>  
> -		/*
> -		 * At least empty ranges has to be defined for parent node if
> -		 * DMA is supported
> -		 */
> -		if (!ranges)
> -			break;
> +		/* Once we find 'dma-ranges', then a missing one is an error */
> +		if (found_dma_ranges && !ranges) {
> +			ret = -ENODEV;
> +			goto out;
> +		}
> +		found_dma_ranges = true;
> +
> +		node = of_get_next_dma_parent(node);
>  	}
>  
> -	if (!ranges) {
> +	if (!node || !ranges) {
>  		pr_debug("no dma-ranges found for node(%pOF)\n", np);
>  		ret = -ENODEV;
>  		goto out;
>  	}
>  
> -	len /= sizeof(u32);
> -
> +	naddr = of_bus_n_addr_cells(node);
> +	nsize = of_bus_n_size_cells(node);
>  	pna = of_n_addr_cells(node);
> +	if ((len / sizeof(__be32)) % (pna + naddr + nsize)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
>  
>  	/* dma-ranges format:
>  	 * DMA addr	: naddr cells
> @@ -978,7 +970,7 @@ int of_dma_get_range(struct device_node *np, u64
> *dma_addr, u64 *paddr, u64 *siz
>  	 * size		: nsize cells
>  	 */
>  	dmaaddr = of_read_number(ranges, naddr);
> -	*paddr = of_translate_dma_address(np, ranges);
> +	*paddr = of_translate_dma_address(node, ranges + naddr);
>  	if (*paddr == OF_BAD_ADDR) {
>  		pr_err("translation of DMA address(%llx) to CPU address failed
> node(%pOF)\n",
>  		       dmaaddr, np);


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Re: [PATCH v2] of: Make of_dma_get_range() work on bus nodes

[Rob Herring]

On Tue, Oct 8, 2019 at 3:52 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> Hi Rob/Robin,
>
> On Tue, 2019-10-08 at 14:52 -0500, Rob Herring wrote:
> > From: Robin Murphy <robin.murphy@arm.com>
> >
> > Since the "dma-ranges" property is only valid for a node representing a
> > bus, of_dma_get_range() currently assumes the node passed in is a leaf
> > representing a device, and starts the walk from its parent. In cases
> > like PCI host controllers on typical FDT systems, however, where the PCI
> > endpoints are probed dynamically the initial leaf node represents the
> > 'bus' itself, and this logic means we fail to consider any "dma-ranges"
> > describing the host bridge itself. Rework the logic such that
> > of_dma_get_range() also works correctly starting from a bus node
> > containing "dma-ranges".
> >
> > While this does mean "dma-ranges" could incorrectly be in a device leaf
> > node, there isn't really any way in this function to ensure that a leaf
> > node is or isn't a bus node.
>
> Sorry, I'm not totally sure if this is what you're pointing out with the last
> sentence. But, what about the case of a bus configuring a device which also
> happens to be a memory mapped bus (say a PCI platform device). It'll get it's
> dma config based on its own dma-ranges which is not what we want.

What I was trying to say is we just can't tell if we should be looking
in the current node or the parent. 'dma-ranges' in a leaf node can be
correct or incorrect.

Your example is a bit different. I'm not sure that case is valid or
can ever work if it is. It's certainly valid that a PCI bridge's
parent has dma-ranges and now we'll actually handle any translation.
The bridge itself is not a DMA-capable device, but just passing thru
DMA. Do we ever need to know the parent's dma-ranges in that case? Or
to put it another way, is looking at anything other than leaf
dma-ranges useful?

Rob

Re: [PATCH v2] of: Make of_dma_get_range() work on bus nodes

[Nicolas Saenz Julienne]

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On Tue, 2019-10-08 at 20:03 -0500, Rob Herring wrote:
> On Tue, Oct 8, 2019 at 3:52 PM Nicolas Saenz Julienne
> <nsaenzjulienne@suse.de> wrote:
> > Hi Rob/Robin,
> > 
> > On Tue, 2019-10-08 at 14:52 -0500, Rob Herring wrote:
> > > From: Robin Murphy <robin.murphy@arm.com>
> > > 
> > > Since the "dma-ranges" property is only valid for a node representing a
> > > bus, of_dma_get_range() currently assumes the node passed in is a leaf
> > > representing a device, and starts the walk from its parent. In cases
> > > like PCI host controllers on typical FDT systems, however, where the PCI
> > > endpoints are probed dynamically the initial leaf node represents the
> > > 'bus' itself, and this logic means we fail to consider any "dma-ranges"
> > > describing the host bridge itself. Rework the logic such that
> > > of_dma_get_range() also works correctly starting from a bus node
> > > containing "dma-ranges".
> > > 
> > > While this does mean "dma-ranges" could incorrectly be in a device leaf
> > > node, there isn't really any way in this function to ensure that a leaf
> > > node is or isn't a bus node.
> > 
> > Sorry, I'm not totally sure if this is what you're pointing out with the
> > last
> > sentence. But, what about the case of a bus configuring a device which also
> > happens to be a memory mapped bus (say a PCI platform device). It'll get
> > it's
> > dma config based on its own dma-ranges which is not what we want.
> 
> What I was trying to say is we just can't tell if we should be looking
> in the current node or the parent. 'dma-ranges' in a leaf node can be
> correct or incorrect.
> 
> Your example is a bit different. I'm not sure that case is valid or
> can ever work if it is. It's certainly valid that a PCI bridge's
> parent has dma-ranges and now we'll actually handle any translation.
> The bridge itself is not a DMA-capable device, but just passing thru
> DMA.

Yes, you're right, I hadn't thought of it from that perspective. Thanks!

> Do we ever need to know the parent's dma-ranges in that case? Or
> to put it another way, is looking at anything other than leaf
> dma-ranges useful?

There is no need at all indeed.

With that,

Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

and

Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

On a Raspberry Pi 4 with pcie-brcmstb.c which is still work in progress but
depends on this.

Regards,
Nicolas


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Re: [PATCH v2] of: Make of_dma_get_range() work on bus nodes

[Robin Murphy]

On 2019-10-08 8:52 pm, Rob Herring wrote:
> From: Robin Murphy <robin.murphy@arm.com>
> 
> Since the "dma-ranges" property is only valid for a node representing a
> bus, of_dma_get_range() currently assumes the node passed in is a leaf
> representing a device, and starts the walk from its parent. In cases
> like PCI host controllers on typical FDT systems, however, where the PCI
> endpoints are probed dynamically the initial leaf node represents the
> 'bus' itself, and this logic means we fail to consider any "dma-ranges"
> describing the host bridge itself. Rework the logic such that
> of_dma_get_range() also works correctly starting from a bus node
> containing "dma-ranges".
> 
> While this does mean "dma-ranges" could incorrectly be in a device leaf
> node, there isn't really any way in this function to ensure that a leaf
> node is or isn't a bus node.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> [robh: Allow for the bus child node to still be passed in]
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
> Resending, hit send too quickly.
> 
> v2:
>   - Ensure once we find dma-ranges, every parent has it.
>   - Only get the #{size,address}-cells after we find non-empty dma-ranges
>   - Add a check on the 'dma-ranges' length
> 
> This is all that remains of the dma-ranges series. I've applied the rest
> of the series prep and fixes. I dropped "of: Ratify of_dma_configure()
> interface" as the assertions that the node pointer being the parent only
> when struct device doesn't have a DT node pointer is not always
> true.

I'd still like to rework of_dma_configure() so that callers don't have 
to pass a redundant node in the common case, but that can wait. For now, 
this looks good enough to un-block the various 32-bit-PCI folks at 
least, and we can consider further improvements on top. For the changes:

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

Cheers,
Robin.

> I didn't include any tested-bys as this has changed a bit. A git branch
> is here[1].
> 
> Rob
> 
> [1] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git dma-masks-v2
> 
>   drivers/of/address.c | 44 ++++++++++++++++++--------------------------
>   1 file changed, 18 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 5ce69d026584..99c1b8058559 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -930,47 +930,39 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
>   	const __be32 *ranges = NULL;
>   	int len, naddr, nsize, pna;
>   	int ret = 0;
> +	bool found_dma_ranges = false;
>   	u64 dmaaddr;
>   
> -	if (!node)
> -		return -EINVAL;
> -
> -	while (1) {
> -		struct device_node *parent;
> -
> -		naddr = of_n_addr_cells(node);
> -		nsize = of_n_size_cells(node);
> -
> -		parent = __of_get_dma_parent(node);
> -		of_node_put(node);
> -
> -		node = parent;
> -		if (!node)
> -			break;
> -
> +	while (node) {
>   		ranges = of_get_property(node, "dma-ranges", &len);
>   
>   		/* Ignore empty ranges, they imply no translation required */
>   		if (ranges && len > 0)
>   			break;
>   
> -		/*
> -		 * At least empty ranges has to be defined for parent node if
> -		 * DMA is supported
> -		 */
> -		if (!ranges)
> -			break;
> +		/* Once we find 'dma-ranges', then a missing one is an error */
> +		if (found_dma_ranges && !ranges) {
> +			ret = -ENODEV;
> +			goto out;
> +		}
> +		found_dma_ranges = true;
> +
> +		node = of_get_next_dma_parent(node);
>   	}
>   
> -	if (!ranges) {
> +	if (!node || !ranges) {
>   		pr_debug("no dma-ranges found for node(%pOF)\n", np);
>   		ret = -ENODEV;
>   		goto out;
>   	}
>   
> -	len /= sizeof(u32);
> -
> +	naddr = of_bus_n_addr_cells(node);
> +	nsize = of_bus_n_size_cells(node);
>   	pna = of_n_addr_cells(node);
> +	if ((len / sizeof(__be32)) % (pna + naddr + nsize)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
>   
>   	/* dma-ranges format:
>   	 * DMA addr	: naddr cells
> @@ -978,7 +970,7 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
>   	 * size		: nsize cells
>   	 */
>   	dmaaddr = of_read_number(ranges, naddr);
> -	*paddr = of_translate_dma_address(np, ranges);
> +	*paddr = of_translate_dma_address(node, ranges + naddr);
>   	if (*paddr == OF_BAD_ADDR) {
>   		pr_err("translation of DMA address(%llx) to CPU address failed node(%pOF)\n",
>   		       dmaaddr, np);
> 

[PATCH v2] of: Make of_dma_get_range() work on bus nodes

[Rob Herring]

From: Robin Murphy <robin.murphy@arm.com>

Since the "dma-ranges" property is only valid for a node representing a
bus, of_dma_get_range() currently assumes the node passed in is a leaf
representing a device, and starts the walk from its parent. In cases
like PCI host controllers on typical FDT systems, however, where the PCI
endpoints are probed dynamically the initial leaf node represents the
'bus' itself, and this logic means we fail to consider any "dma-ranges"
describing the host bridge itself. Rework the logic such that
of_dma_get_range() also works correctly starting from a bus node
containing "dma-ranges".

While this does mean "dma-ranges" could incorrectly be in a device leaf
node, there isn't really any way in this function to ensure that a leaf
node is or isn't a bus node.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[robh: Allow for the bus child node to still be passed in]
Signed-off-by: Rob Herring <robh@kernel.org>

---
v2:
 - Ensure once we find dma-ranges, every parent has it.
 - Only get the #{size,address}-cells after we find non-empty dma-ranges
 - Add a check on the 'dma-ranges' length
---
 drivers/of/address.c | 44 ++++++++++++++++++--------------------------
 1 file changed, 18 insertions(+), 26 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 5ce69d026584..99c1b8058559 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -930,47 +930,39 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	const __be32 *ranges = NULL;
 	int len, naddr, nsize, pna;
 	int ret = 0;
+	bool found_dma_ranges = false;
 	u64 dmaaddr;
 
-	if (!node)
-		return -EINVAL;
-
-	while (1) {
-		struct device_node *parent;
-
-		naddr = of_n_addr_cells(node);
-		nsize = of_n_size_cells(node);
-
-		parent = __of_get_dma_parent(node);
-		of_node_put(node);
-
-		node = parent;
-		if (!node)
-			break;
-
+	while (node) {
 		ranges = of_get_property(node, "dma-ranges", &len);
 
 		/* Ignore empty ranges, they imply no translation required */
 		if (ranges && len > 0)
 			break;
 
-		/*
-		 * At least empty ranges has to be defined for parent node if
-		 * DMA is supported
-		 */
-		if (!ranges)
-			break;
+		/* Once we find 'dma-ranges', then a missing one is an error */
+		if (found_dma_ranges && !ranges) {
+			ret = -ENODEV;
+			goto out;
+		}
+		found_dma_ranges = true;
+
+		node = of_get_next_dma_parent(node);
 	}
 
-	if (!ranges) {
+	if (!node || !ranges) {
 		pr_debug("no dma-ranges found for node(%pOF)\n", np);
 		ret = -ENODEV;
 		goto out;
 	}
 
-	len /= sizeof(u32);
-
+	naddr = of_bus_n_addr_cells(node);
+	nsize = of_bus_n_size_cells(node);
 	pna = of_n_addr_cells(node);
+	if ((len / sizeof(__be32)) % (pna + naddr + nsize)) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	/* dma-ranges format:
 	 * DMA addr	: naddr cells
@@ -978,7 +970,7 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	 * size		: nsize cells
 	 */
 	dmaaddr = of_read_number(ranges, naddr);
-	*paddr = of_translate_dma_address(np, ranges);
+	*paddr = of_translate_dma_address(node, ranges + naddr);
 	if (*paddr == OF_BAD_ADDR) {
 		pr_err("translation of DMA address(%llx) to CPU address failed node(%pOF)\n",
 		       dmaaddr, np);
-- 
2.20.1