Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-16 Thread Rob Herring 
On Thu, Oct 15, 2020 at 12:42 AM Christoph Hellwig  wrote:
>
> > +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> > +{
> > + phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
> > + struct of_range_parser parser;
> > + phys_addr_t subtree_max_addr;
> > + struct device_node *child;
> > + phys_addr_t cpu_end = 0;
> > + struct of_range range;
> > + const __be32 *ranges;
> > + int len;
> > +
> > + if (!np)
> > + np = of_root;
>
> Requiring of_root to be passed explicitly would seem more natural
> to me than the magic NULL argument.  There doesn't seem to be any
> precedent for that kind of calling convention either.

I prefer that of_root is not more widely exposed and NULL regularly
means 'the whole tree'.

Rob
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Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-15 Thread Nicolas Saenz Julienne 
On Thu, 2020-10-15 at 07:42 +0200, Christoph Hellwig wrote:
> > +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> > +{
> > +   phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
> > +   struct of_range_parser parser;
> > +   phys_addr_t subtree_max_addr;
> > +   struct device_node *child;
> > +   phys_addr_t cpu_end = 0;
> > +   struct of_range range;
> > +   const __be32 *ranges;
> > +   int len;
> > +
> > +   if (!np)
> > +   np = of_root;
> 
> Requiring of_root to be passed explicitly would seem more natural
> to me than the magic NULL argument.  There doesn't seem to be any
> precedent for that kind of calling convention either.

I inspired that behavior from __of_find_all_nodes(). I'll change it.



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Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-15 Thread Ard Biesheuvel 
On Thu, 15 Oct 2020 at 11:16, Nicolas Saenz Julienne
 wrote:
>
> On Thu, 2020-10-15 at 08:56 +0200, Ard Biesheuvel wrote:
> > On Thu, 15 Oct 2020 at 00:03, Rob Herring  wrote:
> > > On Wed, Oct 14, 2020 at 2:12 PM Nicolas Saenz Julienne
> > >  wrote:
> > > > Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
> > > > physical address addressable by all DMA masters in the system. It's
> > > > specially useful for setting memory zones sizes at early boot time.
> > > >
> > > > Signed-off-by: Nicolas Saenz Julienne 
> > > >
> > > > ---
> > > >
> > > > Changes since v2:
> > > >  - Use PHYS_ADDR_MAX
> > > >  - return phys_dma_t
> > > >  - Rename function
> > > >  - Correct subject
> > > >  - Add support to start parsing from an arbitrary device node in order
> > > >for the function to work with unit tests
> > > >
> > > >  drivers/of/address.c | 42 ++
> > > >  include/linux/of.h   |  7 +++
> > > >  2 files changed, 49 insertions(+)
> > > >
> > > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > > > index eb9ab4f1e80b..b5a9695aaf82 100644
> > > > --- a/drivers/of/address.c
> > > > +++ b/drivers/of/address.c
> > > > @@ -1024,6 +1024,48 @@ int of_dma_get_range(struct device_node *np, 
> > > > const struct bus_dma_region **map)
> > > >  }
> > > >  #endif /* CONFIG_HAS_DMA */
> > > >
> > > > +/**
> > > > + * of_dma_get_max_cpu_address - Gets highest CPU address suitable for 
> > > > DMA
> > > > + * @np: The node to start searching from or NULL to start from the root
> > > > + *
> > > > + * Gets the highest CPU physical address that is addressable by all 
> > > > DMA masters
> > > > + * in the system (or subtree when np is non-NULL). If no DMA 
> > > > constrained device
> > > > + * is found, it returns PHYS_ADDR_MAX.
> > > > + */
> > > > +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> > > > +{
> > > > +   phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
> > >
> > > One issue with using phys_addr_t is it may be 32-bit even though the
> > > DT is 64-bit addresses. LPAE capable system with LPAE disabled. Maybe
> > > the truncation is fine here? Maybe not.
> > >
> >
> > PHYS_ADDR_MAX is the max addressable CPU address on the system, and so
> > it makes sense to use it for the return type, and for the preliminary
> > return value: this is actually what /prevents/ truncation, because we
> > will only overwrite max_cpu_addr if the new u64 value is lower.
> >
>
> Actually I now see how things might go south.
>
> > > > +   if (ranges && len) {
> > > > +   of_dma_range_parser_init(, np);
> > > > +   for_each_of_range(, )
> > > > +   if (range.cpu_addr + range.size > cpu_end)
> > > > +   cpu_end = range.cpu_addr + range.size;
>
> If cpu_end hits 0x1_, it'll overflow to 0. This is possible on 32-bit
> systems (LPAE or not). And something similar might happen on LPAE disabled
> systems.
>
> I could add some extra logic, something like:
>
> /* We overflowed */
> if (cpu_end < range.cpu_addr)
> cpu_end = PHYS_ADDR_MAX;
>
> Which is not perfect but will cover most sensible cases.
>
> Or simply deal internally in u64s, and upon returning, check if "max_cpu_addr"
> falls higher than PHYS_ADDR_MAX.
>

Just use a u64 for cpu_end

> > > > +
> > > > +   if (max_cpu_addr > cpu_end)
> > > > +   max_cpu_addr = cpu_end;

... then this comparison and assignment will work as expected.

> > > > +   }
> > > > +
> > > > +   for_each_available_child_of_node(np, child) {
> > > > +   subtree_max_addr = of_dma_get_max_cpu_address(child);
> > > > +   if (max_cpu_addr > subtree_max_addr)
> > > > +   max_cpu_addr = subtree_max_addr;
> > > > +   }
> > > > +
> > > > +   return max_cpu_addr;
> > > > +}
>
> Regards,
> Nicolas
>
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Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-15 Thread Nicolas Saenz Julienne 
On Thu, 2020-10-15 at 08:56 +0200, Ard Biesheuvel wrote:
> On Thu, 15 Oct 2020 at 00:03, Rob Herring  wrote:
> > On Wed, Oct 14, 2020 at 2:12 PM Nicolas Saenz Julienne
> >  wrote:
> > > Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
> > > physical address addressable by all DMA masters in the system. It's
> > > specially useful for setting memory zones sizes at early boot time.
> > > 
> > > Signed-off-by: Nicolas Saenz Julienne 
> > > 
> > > ---
> > > 
> > > Changes since v2:
> > >  - Use PHYS_ADDR_MAX
> > >  - return phys_dma_t
> > >  - Rename function
> > >  - Correct subject
> > >  - Add support to start parsing from an arbitrary device node in order
> > >for the function to work with unit tests
> > > 
> > >  drivers/of/address.c | 42 ++
> > >  include/linux/of.h   |  7 +++
> > >  2 files changed, 49 insertions(+)
> > > 
> > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > > index eb9ab4f1e80b..b5a9695aaf82 100644
> > > --- a/drivers/of/address.c
> > > +++ b/drivers/of/address.c
> > > @@ -1024,6 +1024,48 @@ int of_dma_get_range(struct device_node *np, const 
> > > struct bus_dma_region **map)
> > >  }
> > >  #endif /* CONFIG_HAS_DMA */
> > > 
> > > +/**
> > > + * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
> > > + * @np: The node to start searching from or NULL to start from the root
> > > + *
> > > + * Gets the highest CPU physical address that is addressable by all DMA 
> > > masters
> > > + * in the system (or subtree when np is non-NULL). If no DMA constrained 
> > > device
> > > + * is found, it returns PHYS_ADDR_MAX.
> > > + */
> > > +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> > > +{
> > > +   phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
> > 
> > One issue with using phys_addr_t is it may be 32-bit even though the
> > DT is 64-bit addresses. LPAE capable system with LPAE disabled. Maybe
> > the truncation is fine here? Maybe not.
> > 
> 
> PHYS_ADDR_MAX is the max addressable CPU address on the system, and so
> it makes sense to use it for the return type, and for the preliminary
> return value: this is actually what /prevents/ truncation, because we
> will only overwrite max_cpu_addr if the new u64 value is lower.
> 

Actually I now see how things might go south.

> > > +   if (ranges && len) {
> > > +   of_dma_range_parser_init(, np);
> > > +   for_each_of_range(, )
> > > +   if (range.cpu_addr + range.size > cpu_end)
> > > +   cpu_end = range.cpu_addr + range.size;

If cpu_end hits 0x1_, it'll overflow to 0. This is possible on 32-bit
systems (LPAE or not). And something similar might happen on LPAE disabled
systems.

I could add some extra logic, something like:

/* We overflowed */
if (cpu_end < range.cpu_addr)
cpu_end = PHYS_ADDR_MAX;

Which is not perfect but will cover most sensible cases.

Or simply deal internally in u64s, and upon returning, check if "max_cpu_addr"
falls higher than PHYS_ADDR_MAX.

> > > +
> > > +   if (max_cpu_addr > cpu_end)
> > > +   max_cpu_addr = cpu_end;
> > > +   }
> > > +
> > > +   for_each_available_child_of_node(np, child) {
> > > +   subtree_max_addr = of_dma_get_max_cpu_address(child);
> > > +   if (max_cpu_addr > subtree_max_addr)
> > > +   max_cpu_addr = subtree_max_addr;
> > > +   }
> > > +
> > > +   return max_cpu_addr;
> > > +}

Regards,
Nicolas



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Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-15 Thread Nicolas Saenz Julienne 
On Wed, 2020-10-14 at 17:02 -0500, Rob Herring wrote:
> On Wed, Oct 14, 2020 at 2:12 PM Nicolas Saenz Julienne
>  wrote:
> > Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
> > physical address addressable by all DMA masters in the system. It's
> > specially useful for setting memory zones sizes at early boot time.
> > 
> > Signed-off-by: Nicolas Saenz Julienne 
> > 
> > ---

[...]

> > +   struct of_range_parser parser;
> > +   phys_addr_t subtree_max_addr;
> > +   struct device_node *child;
> > +   phys_addr_t cpu_end = 0;
> > +   struct of_range range;
> > +   const __be32 *ranges;
> > +   int len;
> > +
> > +   if (!np)
> > +   np = of_root;
> > +
> > +   ranges = of_get_property(np, "dma-ranges", );
> 
> I'm not really following why you changed the algorithm here. You're
> skipping disabled nodes which is good. Was there some other reason?

Yes, it's a little more complex. But I had to change it in order to be able to
start parsing down from an arbitrary device node, which is needed for the unit
tests.

for_each_of_allnodes() and friends will traverse the whole tree, regardless of
the starting point. I couldn't find a similar function that would just iterate
over a subsection of the tree, so I went with this recursive approach.

Regards,
Nicolas



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Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-15 Thread Ard Biesheuvel 
On Thu, 15 Oct 2020 at 00:03, Rob Herring  wrote:
>
> On Wed, Oct 14, 2020 at 2:12 PM Nicolas Saenz Julienne
>  wrote:
> >
> > Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
> > physical address addressable by all DMA masters in the system. It's
> > specially useful for setting memory zones sizes at early boot time.
> >
> > Signed-off-by: Nicolas Saenz Julienne 
> >
> > ---
> >
> > Changes since v2:
> >  - Use PHYS_ADDR_MAX
> >  - return phys_dma_t
> >  - Rename function
> >  - Correct subject
> >  - Add support to start parsing from an arbitrary device node in order
> >for the function to work with unit tests
> >
> >  drivers/of/address.c | 42 ++
> >  include/linux/of.h   |  7 +++
> >  2 files changed, 49 insertions(+)
> >
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index eb9ab4f1e80b..b5a9695aaf82 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -1024,6 +1024,48 @@ int of_dma_get_range(struct device_node *np, const 
> > struct bus_dma_region **map)
> >  }
> >  #endif /* CONFIG_HAS_DMA */
> >
> > +/**
> > + * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
> > + * @np: The node to start searching from or NULL to start from the root
> > + *
> > + * Gets the highest CPU physical address that is addressable by all DMA 
> > masters
> > + * in the system (or subtree when np is non-NULL). If no DMA constrained 
> > device
> > + * is found, it returns PHYS_ADDR_MAX.
> > + */
> > +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> > +{
> > +   phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
>
> One issue with using phys_addr_t is it may be 32-bit even though the
> DT is 64-bit addresses. LPAE capable system with LPAE disabled. Maybe
> the truncation is fine here? Maybe not.
>

PHYS_ADDR_MAX is the max addressable CPU address on the system, and so
it makes sense to use it for the return type, and for the preliminary
return value: this is actually what /prevents/ truncation, because we
will only overwrite max_cpu_addr if the new u64 value is lower.


> > +   struct of_range_parser parser;
> > +   phys_addr_t subtree_max_addr;
> > +   struct device_node *child;
> > +   phys_addr_t cpu_end = 0;
> > +   struct of_range range;
> > +   const __be32 *ranges;
> > +   int len;
> > +
> > +   if (!np)
> > +   np = of_root;
> > +
> > +   ranges = of_get_property(np, "dma-ranges", );
>
> I'm not really following why you changed the algorithm here. You're
> skipping disabled nodes which is good. Was there some other reason?
>
> > +   if (ranges && len) {
> > +   of_dma_range_parser_init(, np);
> > +   for_each_of_range(, )
> > +   if (range.cpu_addr + range.size > cpu_end)
> > +   cpu_end = range.cpu_addr + range.size;
> > +
> > +   if (max_cpu_addr > cpu_end)
> > +   max_cpu_addr = cpu_end;
> > +   }
> > +
> > +   for_each_available_child_of_node(np, child) {
> > +   subtree_max_addr = of_dma_get_max_cpu_address(child);
> > +   if (max_cpu_addr > subtree_max_addr)
> > +   max_cpu_addr = subtree_max_addr;
> > +   }
> > +
> > +   return max_cpu_addr;
> > +}
> > +
> >  /**
> >   * of_dma_is_coherent - Check if device is coherent
> >   * @np:device node
> > diff --git a/include/linux/of.h b/include/linux/of.h
> > index 481ec0467285..db8db8f2c967 100644
> > --- a/include/linux/of.h
> > +++ b/include/linux/of.h
> > @@ -558,6 +558,8 @@ int of_map_id(struct device_node *np, u32 id,
> >const char *map_name, const char *map_mask_name,
> >struct device_node **target, u32 *id_out);
> >
> > +phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
> > +
> >  #else /* CONFIG_OF */
> >
> >  static inline void of_core_init(void)
> > @@ -995,6 +997,11 @@ static inline int of_map_id(struct device_node *np, 
> > u32 id,
> > return -EINVAL;
> >  }
> >
> > +static inline phys_addr_t of_dma_get_max_cpu_address(struct device_node 
> > *np)
> > +{
> > +   return PHYS_ADDR_MAX;
> > +}
> > +
> >  #define of_match_ptr(_ptr) NULL
> >  #define of_match_node(_matches, _node) NULL
> >  #endif /* CONFIG_OF */
> > --
> > 2.28.0
> >
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Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-14 Thread Christoph Hellwig 
> +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> +{
> + phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
> + struct of_range_parser parser;
> + phys_addr_t subtree_max_addr;
> + struct device_node *child;
> + phys_addr_t cpu_end = 0;
> + struct of_range range;
> + const __be32 *ranges;
> + int len;
> +
> + if (!np)
> + np = of_root;

Requiring of_root to be passed explicitly would seem more natural
to me than the magic NULL argument.  There doesn't seem to be any
precedent for that kind of calling convention either.
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Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-14 Thread Rob Herring 
On Wed, Oct 14, 2020 at 2:12 PM Nicolas Saenz Julienne
 wrote:
>
> Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
> physical address addressable by all DMA masters in the system. It's
> specially useful for setting memory zones sizes at early boot time.
>
> Signed-off-by: Nicolas Saenz Julienne 
>
> ---
>
> Changes since v2:
>  - Use PHYS_ADDR_MAX
>  - return phys_dma_t
>  - Rename function
>  - Correct subject
>  - Add support to start parsing from an arbitrary device node in order
>for the function to work with unit tests
>
>  drivers/of/address.c | 42 ++
>  include/linux/of.h   |  7 +++
>  2 files changed, 49 insertions(+)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index eb9ab4f1e80b..b5a9695aaf82 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -1024,6 +1024,48 @@ int of_dma_get_range(struct device_node *np, const 
> struct bus_dma_region **map)
>  }
>  #endif /* CONFIG_HAS_DMA */
>
> +/**
> + * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
> + * @np: The node to start searching from or NULL to start from the root
> + *
> + * Gets the highest CPU physical address that is addressable by all DMA 
> masters
> + * in the system (or subtree when np is non-NULL). If no DMA constrained 
> device
> + * is found, it returns PHYS_ADDR_MAX.
> + */
> +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> +{
> +   phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;

One issue with using phys_addr_t is it may be 32-bit even though the
DT is 64-bit addresses. LPAE capable system with LPAE disabled. Maybe
the truncation is fine here? Maybe not.

> +   struct of_range_parser parser;
> +   phys_addr_t subtree_max_addr;
> +   struct device_node *child;
> +   phys_addr_t cpu_end = 0;
> +   struct of_range range;
> +   const __be32 *ranges;
> +   int len;
> +
> +   if (!np)
> +   np = of_root;
> +
> +   ranges = of_get_property(np, "dma-ranges", );

I'm not really following why you changed the algorithm here. You're
skipping disabled nodes which is good. Was there some other reason?

> +   if (ranges && len) {
> +   of_dma_range_parser_init(, np);
> +   for_each_of_range(, )
> +   if (range.cpu_addr + range.size > cpu_end)
> +   cpu_end = range.cpu_addr + range.size;
> +
> +   if (max_cpu_addr > cpu_end)
> +   max_cpu_addr = cpu_end;
> +   }
> +
> +   for_each_available_child_of_node(np, child) {
> +   subtree_max_addr = of_dma_get_max_cpu_address(child);
> +   if (max_cpu_addr > subtree_max_addr)
> +   max_cpu_addr = subtree_max_addr;
> +   }
> +
> +   return max_cpu_addr;
> +}
> +
>  /**
>   * of_dma_is_coherent - Check if device is coherent
>   * @np:device node
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 481ec0467285..db8db8f2c967 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -558,6 +558,8 @@ int of_map_id(struct device_node *np, u32 id,
>const char *map_name, const char *map_mask_name,
>struct device_node **target, u32 *id_out);
>
> +phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
> +
>  #else /* CONFIG_OF */
>
>  static inline void of_core_init(void)
> @@ -995,6 +997,11 @@ static inline int of_map_id(struct device_node *np, u32 
> id,
> return -EINVAL;
>  }
>
> +static inline phys_addr_t of_dma_get_max_cpu_address(struct device_node *np)
> +{
> +   return PHYS_ADDR_MAX;
> +}
> +
>  #define of_match_ptr(_ptr) NULL
>  #define of_match_node(_matches, _node) NULL
>  #endif /* CONFIG_OF */
> --
> 2.28.0
>
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[PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

2020-10-14 Thread Nicolas Saenz Julienne 
Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
physical address addressable by all DMA masters in the system. It's
specially useful for setting memory zones sizes at early boot time.

Signed-off-by: Nicolas Saenz Julienne 

---

Changes since v2:
 - Use PHYS_ADDR_MAX
 - return phys_dma_t
 - Rename function
 - Correct subject
 - Add support to start parsing from an arbitrary device node in order
   for the function to work with unit tests

 drivers/of/address.c | 42 ++
 include/linux/of.h   |  7 +++
 2 files changed, 49 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index eb9ab4f1e80b..b5a9695aaf82 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -1024,6 +1024,48 @@ int of_dma_get_range(struct device_node *np, const 
struct bus_dma_region **map)
 }
 #endif /* CONFIG_HAS_DMA */
 
+/**
+ * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
+ * @np: The node to start searching from or NULL to start from the root
+ *
+ * Gets the highest CPU physical address that is addressable by all DMA masters
+ * in the system (or subtree when np is non-NULL). If no DMA constrained device
+ * is found, it returns PHYS_ADDR_MAX.
+ */
+phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
+{
+   phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
+   struct of_range_parser parser;
+   phys_addr_t subtree_max_addr;
+   struct device_node *child;
+   phys_addr_t cpu_end = 0;
+   struct of_range range;
+   const __be32 *ranges;
+   int len;
+
+   if (!np)
+   np = of_root;
+
+   ranges = of_get_property(np, "dma-ranges", );
+   if (ranges && len) {
+   of_dma_range_parser_init(, np);
+   for_each_of_range(, )
+   if (range.cpu_addr + range.size > cpu_end)
+   cpu_end = range.cpu_addr + range.size;
+
+   if (max_cpu_addr > cpu_end)
+   max_cpu_addr = cpu_end;
+   }
+
+   for_each_available_child_of_node(np, child) {
+   subtree_max_addr = of_dma_get_max_cpu_address(child);
+   if (max_cpu_addr > subtree_max_addr)
+   max_cpu_addr = subtree_max_addr;
+   }
+
+   return max_cpu_addr;
+}
+
 /**
  * of_dma_is_coherent - Check if device is coherent
  * @np:device node
diff --git a/include/linux/of.h b/include/linux/of.h
index 481ec0467285..db8db8f2c967 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -558,6 +558,8 @@ int of_map_id(struct device_node *np, u32 id,
   const char *map_name, const char *map_mask_name,
   struct device_node **target, u32 *id_out);
 
+phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
+
 #else /* CONFIG_OF */
 
 static inline void of_core_init(void)
@@ -995,6 +997,11 @@ static inline int of_map_id(struct device_node *np, u32 id,
return -EINVAL;
 }
 
+static inline phys_addr_t of_dma_get_max_cpu_address(struct device_node *np)
+{
+   return PHYS_ADDR_MAX;
+}
+
 #define of_match_ptr(_ptr) NULL
 #define of_match_node(_matches, _node) NULL
 #endif /* CONFIG_OF */
-- 
2.28.0

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