[PATCH v2] arm64: dts: renesas: r8a779g3: Add Argon40 fan HAT DTO to Retronix R-Car V4H Sparrow Hawk

[PATCH v2] arm64: dts: renesas: r8a779g3: Add Argon40 fan HAT DTO to Retronix R-Car V4H Sparrow Hawk

[Marek Vasut]

Add DT overlay to bind Argon40 fan HAT, on Retronix R-Car V4H
Sparrow Hawk board. Fan RPM control and full RPM on reboot has
been tested.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
---
NOTE: Depends on series:
      https://lore.kernel.org/linux-hwmon/20250904202157.170600-1-marek.vasut+renesas@mailbox.org/
---
V2: - Rename the pwm-fan node to pwm-fan-ext to avoid colission
      with existing pwm-fan node in r8a779g3-sparrow-hawk.dts .
      There can be two independent blower fans.
---
 arch/arm64/boot/dts/renesas/Makefile          |  3 +
 .../r8a779g3-sparrow-hawk-fan-argon40.dtso    | 56 +++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100644 arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-fan-argon40.dtso

diff --git a/arch/arm64/boot/dts/renesas/Makefile b/arch/arm64/boot/dts/renesas/Makefile
index bef624636d58b..b2325d1ddf9d3 100644
--- a/arch/arm64/boot/dts/renesas/Makefile
+++ b/arch/arm64/boot/dts/renesas/Makefile
@@ -96,6 +96,9 @@ dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g2-white-hawk-single-ard-audio-da7212.dtb
 
 DTC_FLAGS_r8a779g3-sparrow-hawk += -Wno-spi_bus_bridge
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk.dtb
+dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-fan-argon40.dtbo
+r8a779g3-sparrow-hawk-fan-argon40-dtbs := r8a779g3-sparrow-hawk.dtb r8a779g3-sparrow-hawk-fan-argon40.dtbo
+dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-fan-argon40.dtb
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-fan-pwm.dtbo
 r8a779g3-sparrow-hawk-fan-pwm-dtbs := r8a779g3-sparrow-hawk.dtb r8a779g3-sparrow-hawk-fan-pwm.dtbo
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-fan-pwm.dtb
diff --git a/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-fan-argon40.dtso b/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-fan-argon40.dtso
new file mode 100644
index 0000000000000..f7c144eb63920
--- /dev/null
+++ b/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-fan-argon40.dtso
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/*
+ * Device Tree Overlay for the Argon40 HAT blower fan in connector CN7
+ * on R-Car V4H ES3.0 Sparrow Hawk board
+ *
+ * Copyright (C) 2025 Marek Vasut <marek.vasut+renesas@mailbox.org>
+ *
+ * Example usage:
+ *
+ * # Localize hwmon sysfs directory that matches the PWM fan,
+ * # enable the PWM fan, and configure the fan speed manually.
+ * r8a779g3-sparrow-hawk$ grep -H . /sys/class/hwmon/hwmon?/name
+ * /sys/class/hwmon/hwmon0/name:sensor1_thermal
+ * /sys/class/hwmon/hwmon1/name:sensor2_thermal
+ * /sys/class/hwmon/hwmon2/name:sensor3_thermal
+ * /sys/class/hwmon/hwmon3/name:sensor4_thermal
+ * /sys/class/hwmon/hwmon4/name:pwmfan
+ *                       ^      ^^^^^^
+ *
+ * # Select mode 2 , enable fan PWM and regulator and keep them enabled.
+ * # For details, see Linux Documentation/hwmon/pwm-fan.rst
+ * r8a779g3-sparrow-hawk$ echo 2 > /sys/class/hwmon/hwmon4/pwm1_enable
+ *
+ * # Configure PWM fan speed in range 0..255 , 0 is stopped , 255 is full speed .
+ * # Fan speed 101 is about 2/5 of the PWM fan speed:
+ * r8a779g3-sparrow-hawk$ echo 101 > /sys/class/hwmon/hwmon4/pwm1
+ */
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+	pwm-fan-ext {
+		compatible = "pwm-fan";
+		#cooling-cells = <2>;
+		/* PWM period: 33us ~= 30 kHz */
+		pwms = <&pwmhat 0 33334 0>;
+		/* Available cooling levels */
+		cooling-levels = <0 50 100 150 200 255>;
+		fan-shutdown-percent = <100>;
+	};
+};
+
+/* Page 31 / IO_CN */
+&i2c3 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	clock-frequency = <400000>;
+	status = "okay";
+
+	pwmhat: pwm@1a {
+		compatible = "argon40,fan-hat";
+		reg = <0x1a>;
+		#pwm-cells = <3>;
+	};
+};
-- 
2.50.1

Re: [PATCH v2] arm64: dts: renesas: r8a779g3: Add Argon40 fan HAT DTO to Retronix R-Car V4H Sparrow Hawk

[Wolfram Sang]

Hi Marek,

On Fri, Sep 05, 2025 at 04:00:57AM +0200, Marek Vasut wrote:
> Add DT overlay to bind Argon40 fan HAT, on Retronix R-Car V4H
> Sparrow Hawk board. Fan RPM control and full RPM on reboot has
> been tested.
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

Basically works for me as well, so:

Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

> + * r8a779g3-sparrow-hawk$ grep -H . /sys/class/hwmon/hwmon?/name
> + * /sys/class/hwmon/hwmon0/name:sensor1_thermal
> + * /sys/class/hwmon/hwmon1/name:sensor2_thermal
> + * /sys/class/hwmon/hwmon2/name:sensor3_thermal
> + * /sys/class/hwmon/hwmon3/name:sensor4_thermal
> + * /sys/class/hwmon/hwmon4/name:pwmfan
> + *                       ^      ^^^^^^

For me, the output looks different, though:

/sys/class/hwmon/hwmon0/name:pwmfan
/sys/class/hwmon/hwmon1/name:sensor1_thermal
/sys/class/hwmon/hwmon2/name:sensor2_thermal
/sys/class/hwmon/hwmon3/name:sensor3_thermal
/sys/class/hwmon/hwmon4/name:sensor4_thermal
/sys/class/hwmon/hwmon5/name:pwmfan

hwmon0 is the Argon, hwmon5 the (unpopulated) on board connector.

I hope the naming is stable, but in any case, the docs need to be
reworked a little, I guess?

Thanks for your work!

   Wolfram

Re: [PATCH v2] arm64: dts: renesas: r8a779g3: Add Argon40 fan HAT DTO to Retronix R-Car V4H Sparrow Hawk

[Marek Vasut]

On 9/5/25 2:30 PM, Wolfram Sang wrote:
> Hi Marek,

Hello Wolfram,

>> + * r8a779g3-sparrow-hawk$ grep -H . /sys/class/hwmon/hwmon?/name
>> + * /sys/class/hwmon/hwmon0/name:sensor1_thermal
>> + * /sys/class/hwmon/hwmon1/name:sensor2_thermal
>> + * /sys/class/hwmon/hwmon2/name:sensor3_thermal
>> + * /sys/class/hwmon/hwmon3/name:sensor4_thermal
>> + * /sys/class/hwmon/hwmon4/name:pwmfan
>> + *                       ^      ^^^^^^
> 
> For me, the output looks different, though:
> 
> /sys/class/hwmon/hwmon0/name:pwmfan
> /sys/class/hwmon/hwmon1/name:sensor1_thermal
> /sys/class/hwmon/hwmon2/name:sensor2_thermal
> /sys/class/hwmon/hwmon3/name:sensor3_thermal
> /sys/class/hwmon/hwmon4/name:sensor4_thermal
> /sys/class/hwmon/hwmon5/name:pwmfan
> 
> hwmon0 is the Argon, hwmon5 the (unpopulated) on board connector.
> 
> I hope the naming is stable, but in any case, the docs need to be
> reworked a little, I guess?

The hwmon devices are allocated first come first served, so the list can 
look different for you. You need to look up the fan you want to control, 
of course. Look up by name is simplest, if there are more fans, it might 
be a bit more involved to find the right one.

-- 
Best regards,
Marek Vasut

Re: [PATCH v2] arm64: dts: renesas: r8a779g3: Add Argon40 fan HAT DTO to Retronix R-Car V4H Sparrow Hawk

[Wolfram Sang]

Hi Marek,

> > > + * r8a779g3-sparrow-hawk$ grep -H . /sys/class/hwmon/hwmon?/name
> > > + * /sys/class/hwmon/hwmon0/name:sensor1_thermal
> > > + * /sys/class/hwmon/hwmon1/name:sensor2_thermal
> > > + * /sys/class/hwmon/hwmon2/name:sensor3_thermal
> > > + * /sys/class/hwmon/hwmon3/name:sensor4_thermal
> > > + * /sys/class/hwmon/hwmon4/name:pwmfan
> > > + *                       ^      ^^^^^^
> > 
> > For me, the output looks different, though:
> > 
> > /sys/class/hwmon/hwmon0/name:pwmfan
> > /sys/class/hwmon/hwmon1/name:sensor1_thermal
> > /sys/class/hwmon/hwmon2/name:sensor2_thermal
> > /sys/class/hwmon/hwmon3/name:sensor3_thermal
> > /sys/class/hwmon/hwmon4/name:sensor4_thermal
> > /sys/class/hwmon/hwmon5/name:pwmfan
> > 
> > hwmon0 is the Argon, hwmon5 the (unpopulated) on board connector.
> > 
> > I hope the naming is stable, but in any case, the docs need to be
> > reworked a little, I guess?
> 
> The hwmon devices are allocated first come first served, so the list can
> look different for you. You need to look up the fan you want to control, of
> course. Look up by name is simplest, if there are more fans, it might be a
> bit more involved to find the right one.

Exactly. This is why I would suggest to drop the '^^^^^' line from
above. We definitely have two pwmfans with the above dtso. So finding
the right one needs a second look anyhow. And while I think it is quite
likely that the list of hwmon devices will look the same (I don't see a
race condition which would make hwmon0 and hwmon5 swap), I agree we
shouldn't rely on it. I would also think that we then maybe should
change

	echo 2 > /sys/class/hwmon/hwmon4/pwm1_enable

to

	echo 2 > /sys/class/hwmon/hwmon<X>/pwm1_enable

or something? What do you think? Just suggestions, I am not really
insisting. Well, maybe, about dropping the "^^^^" line ;)

Happy hacking,

   Wolfram

Re: [PATCH v2] arm64: dts: renesas: r8a779g3: Add Argon40 fan HAT DTO to Retronix R-Car V4H Sparrow Hawk

[Marek Vasut]

On 9/5/25 10:04 PM, Wolfram Sang wrote:

Hello Wolfram,

>>>> + * r8a779g3-sparrow-hawk$ grep -H . /sys/class/hwmon/hwmon?/name
>>>> + * /sys/class/hwmon/hwmon0/name:sensor1_thermal
>>>> + * /sys/class/hwmon/hwmon1/name:sensor2_thermal
>>>> + * /sys/class/hwmon/hwmon2/name:sensor3_thermal
>>>> + * /sys/class/hwmon/hwmon3/name:sensor4_thermal
>>>> + * /sys/class/hwmon/hwmon4/name:pwmfan
>>>> + *                       ^      ^^^^^^
>>>
>>> For me, the output looks different, though:
>>>
>>> /sys/class/hwmon/hwmon0/name:pwmfan
>>> /sys/class/hwmon/hwmon1/name:sensor1_thermal
>>> /sys/class/hwmon/hwmon2/name:sensor2_thermal
>>> /sys/class/hwmon/hwmon3/name:sensor3_thermal
>>> /sys/class/hwmon/hwmon4/name:sensor4_thermal
>>> /sys/class/hwmon/hwmon5/name:pwmfan
>>>
>>> hwmon0 is the Argon, hwmon5 the (unpopulated) on board connector.
>>>
>>> I hope the naming is stable, but in any case, the docs need to be
>>> reworked a little, I guess?
>>
>> The hwmon devices are allocated first come first served, so the list can
>> look different for you. You need to look up the fan you want to control, of
>> course. Look up by name is simplest, if there are more fans, it might be a
>> bit more involved to find the right one.
> 
> Exactly. This is why I would suggest to drop the '^^^^^' line from
> above. We definitely have two pwmfans with the above dtso. So finding
> the right one needs a second look anyhow. And while I think it is quite
> likely that the list of hwmon devices will look the same (I don't see a
> race condition which would make hwmon0 and hwmon5 swap), I agree we
> shouldn't rely on it. I would also think that we then maybe should
> change
> 
> 	echo 2 > /sys/class/hwmon/hwmon4/pwm1_enable
> 
> to
> 
> 	echo 2 > /sys/class/hwmon/hwmon<X>/pwm1_enable
> 
> or something? What do you think? Just suggestions, I am not really
> insisting. Well, maybe, about dropping the "^^^^" line ;)
I hope the V3 comment will be to your liking , as it addresses this 
part. I'll then send separate update for the native fan DTO once we 
agree on this wording.