Add some example usage of the device property methods for reading
DT/ACPI/swnode child nodes and reference args.
Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
---
drivers/of/unittest-data/tests-platform.dtsi | 7 +++++++
samples/rust/rust_driver_platform.rs | 13 ++++++++++++-
2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/drivers/of/unittest-data/tests-platform.dtsi b/drivers/of/unittest-data/tests-platform.dtsi
index 50a51f38afb6..509eb614ab2b 100644
--- a/drivers/of/unittest-data/tests-platform.dtsi
+++ b/drivers/of/unittest-data/tests-platform.dtsi
@@ -40,6 +40,13 @@ test-device@2 {
test,u32-prop = <0xdeadbeef>;
test,i16-array = /bits/ 16 <1 2 (-3) (-4)>;
+
+ ref_child_0: child@0 {
+ test,ref-arg = <&ref_child_1 0x20 0x32>;
+ };
+ ref_child_1: child@1 {
+ test,ref-arg = <&ref_child_0 0x10 0x64>;
+ };
};
};
diff --git a/samples/rust/rust_driver_platform.rs b/samples/rust/rust_driver_platform.rs
index c0abf78d0683..4dcedb22a4bb 100644
--- a/samples/rust/rust_driver_platform.rs
+++ b/samples/rust/rust_driver_platform.rs
@@ -4,7 +4,11 @@
use kernel::{
c_str,
- device::{self, Core},
+ device::{
+ self,
+ property::{FwNodeReferenceArgs, NArgs},
+ Core,
+ },
of, platform,
prelude::*,
str::CString,
@@ -91,6 +95,13 @@ fn properties_parse(dev: &device::Device) -> Result {
let prop: KVec<i16> = fwnode.property_read_array_vec(name, 4)?.required_by(dev)?;
dev_info!(dev, "'{name}'='{prop:?}' (KVec)\n");
+ for child in fwnode.children() {
+ let name = c_str!("test,ref-arg");
+ let nargs = NArgs::N(2);
+ let prop: FwNodeReferenceArgs = child.property_get_reference_args(name, nargs, 0)?;
+ dev_info!(dev, "'{name}'='{prop:?}'\n");
+ }
+
Ok(())
}
}
--
2.49.0On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
>
> Add some example usage of the device property methods for reading
> DT/ACPI/swnode child nodes and reference args.
>
> Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
> ---
> drivers/of/unittest-data/tests-platform.dtsi | 7 +++++++
> samples/rust/rust_driver_platform.rs | 13 ++++++++++++-
> 2 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/unittest-data/tests-platform.dtsi b/drivers/of/unittest-data/tests-platform.dtsi
> index 50a51f38afb6..509eb614ab2b 100644
> --- a/drivers/of/unittest-data/tests-platform.dtsi
> +++ b/drivers/of/unittest-data/tests-platform.dtsi
> @@ -40,6 +40,13 @@ test-device@2 {
>
> test,u32-prop = <0xdeadbeef>;
> test,i16-array = /bits/ 16 <1 2 (-3) (-4)>;
> +
> + ref_child_0: child@0 {
child-0 or you need to add 'reg' property if you keep the unit-address.
> + test,ref-arg = <&ref_child_1 0x20 0x32>;
> + };
> + ref_child_1: child@1 {
> + test,ref-arg = <&ref_child_0 0x10 0x64>;
> + };
> };
> };
>
> diff --git a/samples/rust/rust_driver_platform.rs b/samples/rust/rust_driver_platform.rs
> index c0abf78d0683..4dcedb22a4bb 100644
> --- a/samples/rust/rust_driver_platform.rs
> +++ b/samples/rust/rust_driver_platform.rs
> @@ -4,7 +4,11 @@
>
> use kernel::{
> c_str,
> - device::{self, Core},
> + device::{
> + self,
> + property::{FwNodeReferenceArgs, NArgs},
> + Core,
> + },
> of, platform,
> prelude::*,
> str::CString,
> @@ -91,6 +95,13 @@ fn properties_parse(dev: &device::Device) -> Result {
> let prop: KVec<i16> = fwnode.property_read_array_vec(name, 4)?.required_by(dev)?;
> dev_info!(dev, "'{name}'='{prop:?}' (KVec)\n");
>
> + for child in fwnode.children() {
> + let name = c_str!("test,ref-arg");
> + let nargs = NArgs::N(2);
> + let prop: FwNodeReferenceArgs = child.property_get_reference_args(name, nargs, 0)?;
Is there some reason we can just pass 2 in rather than nargs? Seems
overly verbose for my tastes.
> + dev_info!(dev, "'{name}'='{prop:?}'\n");
> + }
> +
> Ok(())
> }
> }
> --
> 2.49.0
>
On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
> >
> > Add some example usage of the device property methods for reading
> > DT/ACPI/swnode child nodes and reference args.
> >
> > Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
> > ---
> > drivers/of/unittest-data/tests-platform.dtsi | 7 +++++++
> > samples/rust/rust_driver_platform.rs | 13 ++++++++++++-
> > 2 files changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/of/unittest-data/tests-platform.dtsi b/drivers/of/unittest-data/tests-platform.dtsi
> > index 50a51f38afb6..509eb614ab2b 100644
> > --- a/drivers/of/unittest-data/tests-platform.dtsi
> > +++ b/drivers/of/unittest-data/tests-platform.dtsi
> > @@ -40,6 +40,13 @@ test-device@2 {
> >
> > test,u32-prop = <0xdeadbeef>;
> > test,i16-array = /bits/ 16 <1 2 (-3) (-4)>;
> > +
> > + ref_child_0: child@0 {
>
> child-0 or you need to add 'reg' property if you keep the unit-address.
Adding child nodes here creates the following dt-test failues.
[ 1.031239] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
[ 1.031647] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
@Rob: What do you suggest?
>
> > + test,ref-arg = <&ref_child_1 0x20 0x32>;
> > + };
> > + ref_child_1: child@1 {
> > + test,ref-arg = <&ref_child_0 0x10 0x64>;
> > + };
> > };
> > };
On Sat, Jun 21, 2025 at 12:37:27AM +0200, Danilo Krummrich wrote:
> On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
> > On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
> > >
> > > Add some example usage of the device property methods for reading
> > > DT/ACPI/swnode child nodes and reference args.
> > >
> > > Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
> > > ---
> > > drivers/of/unittest-data/tests-platform.dtsi | 7 +++++++
> > > samples/rust/rust_driver_platform.rs | 13 ++++++++++++-
> > > 2 files changed, 19 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/of/unittest-data/tests-platform.dtsi b/drivers/of/unittest-data/tests-platform.dtsi
> > > index 50a51f38afb6..509eb614ab2b 100644
> > > --- a/drivers/of/unittest-data/tests-platform.dtsi
> > > +++ b/drivers/of/unittest-data/tests-platform.dtsi
> > > @@ -40,6 +40,13 @@ test-device@2 {
> > >
> > > test,u32-prop = <0xdeadbeef>;
> > > test,i16-array = /bits/ 16 <1 2 (-3) (-4)>;
> > > +
> > > + ref_child_0: child@0 {
> >
> > child-0 or you need to add 'reg' property if you keep the unit-address.
>
> Adding child nodes here creates the following dt-test failues.
>
> [ 1.031239] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
> [ 1.031647] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
>
> @Rob: What do you suggest?
This should fix it:
index eeb370e0f507..e3503ec20f6c 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1856,6 +1856,8 @@ static void __init of_unittest_platform_populate(void)
of_platform_populate(np, match, NULL, &test_bus->dev);
for_each_child_of_node(np, child) {
for_each_child_of_node(child, grandchild) {
+ if (!of_property_present(grandchild, "compatible"))
+ continue;
pdev = of_find_device_by_node(grandchild);
unittest(pdev,
"Could not create device for node '%pOFn'\n",
On 6/25/25 4:39 PM, Rob Herring wrote:
> On Sat, Jun 21, 2025 at 12:37:27AM +0200, Danilo Krummrich wrote:
>> On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
>>> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
>>>>
>>>> Add some example usage of the device property methods for reading
>>>> DT/ACPI/swnode child nodes and reference args.
>>>>
>>>> Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
>>>> ---
>>>> drivers/of/unittest-data/tests-platform.dtsi | 7 +++++++
>>>> samples/rust/rust_driver_platform.rs | 13 ++++++++++++-
>>>> 2 files changed, 19 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/of/unittest-data/tests-platform.dtsi b/drivers/of/unittest-data/tests-platform.dtsi
>>>> index 50a51f38afb6..509eb614ab2b 100644
>>>> --- a/drivers/of/unittest-data/tests-platform.dtsi
>>>> +++ b/drivers/of/unittest-data/tests-platform.dtsi
>>>> @@ -40,6 +40,13 @@ test-device@2 {
>>>>
>>>> test,u32-prop = <0xdeadbeef>;
>>>> test,i16-array = /bits/ 16 <1 2 (-3) (-4)>;
>>>> +
>>>> + ref_child_0: child@0 {
>>>
>>> child-0 or you need to add 'reg' property if you keep the unit-address.
>>
>> Adding child nodes here creates the following dt-test failues.
>>
>> [ 1.031239] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
>> [ 1.031647] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
>>
>> @Rob: What do you suggest?
>
> This should fix it:
>
> index eeb370e0f507..e3503ec20f6c 100644
> --- a/drivers/of/unittest.c
> +++ b/drivers/of/unittest.c
> @@ -1856,6 +1856,8 @@ static void __init of_unittest_platform_populate(void)
> of_platform_populate(np, match, NULL, &test_bus->dev);
> for_each_child_of_node(np, child) {
> for_each_child_of_node(child, grandchild) {
> + if (!of_property_present(grandchild, "compatible"))
> + continue;
> pdev = of_find_device_by_node(grandchild);
> unittest(pdev,
> "Could not create device for node '%pOFn'\n",
>
Do you want this to be a separate patch? Otherwise, I'd fine just adding it to
this one.
On Wed, Jun 25, 2025 at 10:09 AM Danilo Krummrich <dakr@kernel.org> wrote:
>
> On 6/25/25 4:39 PM, Rob Herring wrote:
> > On Sat, Jun 21, 2025 at 12:37:27AM +0200, Danilo Krummrich wrote:
> >> On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
> >>> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
> >>>>
> >>>> Add some example usage of the device property methods for reading
> >>>> DT/ACPI/swnode child nodes and reference args.
> >>>>
> >>>> Signed-off-by: Remo Senekowitsch <remo@buenzli.dev>
> >>>> ---
> >>>> drivers/of/unittest-data/tests-platform.dtsi | 7 +++++++
> >>>> samples/rust/rust_driver_platform.rs | 13 ++++++++++++-
> >>>> 2 files changed, 19 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/drivers/of/unittest-data/tests-platform.dtsi b/drivers/of/unittest-data/tests-platform.dtsi
> >>>> index 50a51f38afb6..509eb614ab2b 100644
> >>>> --- a/drivers/of/unittest-data/tests-platform.dtsi
> >>>> +++ b/drivers/of/unittest-data/tests-platform.dtsi
> >>>> @@ -40,6 +40,13 @@ test-device@2 {
> >>>>
> >>>> test,u32-prop = <0xdeadbeef>;
> >>>> test,i16-array = /bits/ 16 <1 2 (-3) (-4)>;
> >>>> +
> >>>> + ref_child_0: child@0 {
> >>>
> >>> child-0 or you need to add 'reg' property if you keep the unit-address.
> >>
> >> Adding child nodes here creates the following dt-test failues.
> >>
> >> [ 1.031239] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
> >> [ 1.031647] ### dt-test ### FAIL of_unittest_platform_populate():1862 Could not create device for node 'child'
> >>
> >> @Rob: What do you suggest?
> >
> > This should fix it:
> >
> > index eeb370e0f507..e3503ec20f6c 100644
> > --- a/drivers/of/unittest.c
> > +++ b/drivers/of/unittest.c
> > @@ -1856,6 +1856,8 @@ static void __init of_unittest_platform_populate(void)
> > of_platform_populate(np, match, NULL, &test_bus->dev);
> > for_each_child_of_node(np, child) {
> > for_each_child_of_node(child, grandchild) {
> > + if (!of_property_present(grandchild, "compatible"))
> > + continue;
> > pdev = of_find_device_by_node(grandchild);
> > unittest(pdev,
> > "Could not create device for node '%pOFn'\n",
> >
>
> Do you want this to be a separate patch? Otherwise, I'd fine just adding it to
> this one.
Adding it here is fine.
Rob
On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
> > @@ -91,6 +95,13 @@ fn properties_parse(dev: &device::Device) -> Result {
> > let prop: KVec<i16> = fwnode.property_read_array_vec(name, 4)?.required_by(dev)?;
> > dev_info!(dev, "'{name}'='{prop:?}' (KVec)\n");
> >
> > + for child in fwnode.children() {
> > + let name = c_str!("test,ref-arg");
> > + let nargs = NArgs::N(2);
> > + let prop: FwNodeReferenceArgs = child.property_get_reference_args(name, nargs, 0)?;
>
> Is there some reason we can just pass 2 in rather than nargs? Seems
> overly verbose for my tastes.
It's because you could also pass NArgs::Prop("foo-bar") to indicate the the
name of the property telling the number of arguments.
NArgs is defined as
pub enum NArgs<'a> {
/// The name of the property of the reference indicating the number of
/// arguments.
Prop(&'a CStr),
/// The known number of arguments.
N(u32),
}
and FwNode::property_get_reference_args() can match against the corresponding
enum variant to cover both cases.
> > + dev_info!(dev, "'{name}'='{prop:?}'\n");
> > + }
> > +
> > Ok(())
> > }
> > }
> > --
> > 2.49.0
> >
On Tue Jun 17, 2025 at 3:11 PM CEST, Danilo Krummrich wrote:
> On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
>> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
>> > @@ -91,6 +95,13 @@ fn properties_parse(dev: &device::Device) -> Result {
>> > let prop: KVec<i16> = fwnode.property_read_array_vec(name, 4)?.required_by(dev)?;
>> > dev_info!(dev, "'{name}'='{prop:?}' (KVec)\n");
>> >
>> > + for child in fwnode.children() {
>> > + let name = c_str!("test,ref-arg");
>> > + let nargs = NArgs::N(2);
>> > + let prop: FwNodeReferenceArgs = child.property_get_reference_args(name, nargs, 0)?;
>>
>> Is there some reason we can just pass 2 in rather than nargs? Seems
>> overly verbose for my tastes.
>
> It's because you could also pass NArgs::Prop("foo-bar") to indicate the the
> name of the property telling the number of arguments.
>
> NArgs is defined as
>
> pub enum NArgs<'a> {
> /// The name of the property of the reference indicating the number of
> /// arguments.
> Prop(&'a CStr),
> /// The known number of arguments.
> N(u32),
> }
>
> and FwNode::property_get_reference_args() can match against the corresponding
> enum variant to cover both cases.
I guess we could make the function generic if that's deemed worth it?
A trait and an implementation for `u32` and `&CStr` each. Similar to how
we made `property_read` generic.
>> > + dev_info!(dev, "'{name}'='{prop:?}'\n");
>> > + }
>> > +
>> > Ok(())
>> > }
>> > }
>> > --
>> > 2.49.0
>> >
On Wed, Jun 18, 2025 at 01:37:08PM +0200, Remo Senekowitsch wrote:
> On Tue Jun 17, 2025 at 3:11 PM CEST, Danilo Krummrich wrote:
> > On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
> >> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
> >> > @@ -91,6 +95,13 @@ fn properties_parse(dev: &device::Device) -> Result {
> >> > let prop: KVec<i16> = fwnode.property_read_array_vec(name, 4)?.required_by(dev)?;
> >> > dev_info!(dev, "'{name}'='{prop:?}' (KVec)\n");
> >> >
> >> > + for child in fwnode.children() {
> >> > + let name = c_str!("test,ref-arg");
> >> > + let nargs = NArgs::N(2);
> >> > + let prop: FwNodeReferenceArgs = child.property_get_reference_args(name, nargs, 0)?;
> >>
> >> Is there some reason we can just pass 2 in rather than nargs? Seems
> >> overly verbose for my tastes.
> >
> > It's because you could also pass NArgs::Prop("foo-bar") to indicate the the
> > name of the property telling the number of arguments.
> >
> > NArgs is defined as
> >
> > pub enum NArgs<'a> {
> > /// The name of the property of the reference indicating the number of
> > /// arguments.
> > Prop(&'a CStr),
> > /// The known number of arguments.
> > N(u32),
> > }
> >
> > and FwNode::property_get_reference_args() can match against the corresponding
> > enum variant to cover both cases.
>
> I guess we could make the function generic if that's deemed worth it?
> A trait and an implementation for `u32` and `&CStr` each. Similar to how
> we made `property_read` generic.
There is a case where the cells property is optional and we fallback to
0 cells if not found. #msi-cells is an example. I imagine NArgs could
express that while a generic could not? In any case, I don't expect
drivers to have to deal with that as it would be subsystem code handling
it.
As-is is fine I think. This function isn't too widely used that it could
be changed later if we change our minds.
Rob
On Wed, Jun 18, 2025 at 08:31:55AM -0500, Rob Herring wrote:
> On Wed, Jun 18, 2025 at 01:37:08PM +0200, Remo Senekowitsch wrote:
> > On Tue Jun 17, 2025 at 3:11 PM CEST, Danilo Krummrich wrote:
> > > On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
> > >> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
> > >> > @@ -91,6 +95,13 @@ fn properties_parse(dev: &device::Device) -> Result {
> > >> > let prop: KVec<i16> = fwnode.property_read_array_vec(name, 4)?.required_by(dev)?;
> > >> > dev_info!(dev, "'{name}'='{prop:?}' (KVec)\n");
> > >> >
> > >> > + for child in fwnode.children() {
> > >> > + let name = c_str!("test,ref-arg");
> > >> > + let nargs = NArgs::N(2);
> > >> > + let prop: FwNodeReferenceArgs = child.property_get_reference_args(name, nargs, 0)?;
> > >>
> > >> Is there some reason we can just pass 2 in rather than nargs? Seems
> > >> overly verbose for my tastes.
> > >
> > > It's because you could also pass NArgs::Prop("foo-bar") to indicate the the
> > > name of the property telling the number of arguments.
> > >
> > > NArgs is defined as
> > >
> > > pub enum NArgs<'a> {
> > > /// The name of the property of the reference indicating the number of
> > > /// arguments.
> > > Prop(&'a CStr),
> > > /// The known number of arguments.
> > > N(u32),
> > > }
> > >
> > > and FwNode::property_get_reference_args() can match against the corresponding
> > > enum variant to cover both cases.
> >
> > I guess we could make the function generic if that's deemed worth it?
> > A trait and an implementation for `u32` and `&CStr` each. Similar to how
> > we made `property_read` generic.
I don't think that's worth it; I think the current version is fine as it is.
> There is a case where the cells property is optional and we fallback to
> 0 cells if not found. #msi-cells is an example. I imagine NArgs could
> express that while a generic could not? In any case, I don't expect
> drivers to have to deal with that as it would be subsystem code handling
> it.
>
> As-is is fine I think. This function isn't too widely used that it could
> be changed later if we change our minds.
Agreed.
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