Add a DT overlay to bind the WaveShare 2-Channel Isolated CAN FD
Expansion HAT on the Retronix R-Car V4H Sparrow Hawk board.

Current device link is at https://www.waveshare.com/2-ch-can-fd-hat.htm

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-kernel@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
---
V2: - Drop the unique spi controller node identifier
    - Switch IRQ to active low
    - Sort compatible and reg properties
    - Add "CN7 pin 22" comment
    - Move pwm1 node to the top and add comment
    - Rename MSIOF0 PFC node
---
 arch/arm64/boot/dts/renesas/Makefile          |   3 +
 .../r8a779g3-sparrow-hawk-ws-2ch-canfd.dtso   | 135 ++++++++++++++++++
 2 files changed, 138 insertions(+)
 create mode 100644 arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-ws-2ch-canfd.dtso

diff --git a/arch/arm64/boot/dts/renesas/Makefile b/arch/arm64/boot/dts/renesas/Makefile
index e4a7d7ab5b0e9..b742baf509a14 100644
--- a/arch/arm64/boot/dts/renesas/Makefile
+++ b/arch/arm64/boot/dts/renesas/Makefile
@@ -124,6 +124,9 @@ dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-rpi-display-2-5in.dtb
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-rpi-display-2-7in.dtbo
 r8a779g3-sparrow-hawk-rpi-display-2-7in-dtbs := r8a779g3-sparrow-hawk.dtb r8a779g3-sparrow-hawk-rpi-display-2-7in.dtbo
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-rpi-display-2-7in.dtb
+dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-ws-2ch-canfd.dtbo
+r8a779g3-sparrow-hawk-ws-2ch-canfd-dtbs := r8a779g3-sparrow-hawk.dtb r8a779g3-sparrow-hawk-ws-2ch-canfd.dtbo
+dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-ws-2ch-canfd.dtb
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-ws-display-13in.dtbo
 r8a779g3-sparrow-hawk-ws-display-13in-dtbs := r8a779g3-sparrow-hawk.dtb r8a779g3-sparrow-hawk-ws-display-13in.dtbo
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-ws-display-13in.dtb
diff --git a/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-ws-2ch-canfd.dtso b/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-ws-2ch-canfd.dtso
new file mode 100644
index 0000000000000..213bac3e3abca
--- /dev/null
+++ b/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-ws-2ch-canfd.dtso
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/*
+ * Device Tree Overlay for the Waveshare 2-Channel Isolated CAN FD HAT
+ * on connector CN7 on R-Car V4H ES3.0 Sparrow Hawk board
+ *
+ * Copyright (C) 2026 Marek Vasut <marek.vasut+renesas@mailbox.org>
+ *
+ * Example usage:
+ * - Connect HAT signals to Sparrow Hawk board CAN BUS connector CONN2:
+ *   HAT CAN_0 H -- CONN2 pin 6
+ *   HAT CAN_0 L -- CONN2 pin 2
+ *   HAT CAN_1 H -- CONN2 pin 5
+ *   HAT CAN_1 L -- CONN2 pin 1
+ *
+ * - Determine which interface is which:
+ *   $ ip -d link show
+ *   2: can0: <NOARP,ECHO> ...
+ *      ...
+ *        clock 40000000 ... e6660000.can <------ Native Renesas CANFD
+ *   3: can1: <NOARP,ECHO> ...
+ *      ...
+ *   4: can2: <NOARP,ECHO> ...
+ *      ...
+ *        clock 40000000 ... spi1.0 <------------ SPI CANFD on this HAT
+ *   5: can3: <NOARP,ECHO> ...
+ *      ...
+ *
+ * - Bring connected interfaces up:
+ *   # CAN_0 link
+ *   $ ip link set can0 up type can bitrate 125000 dbitrate 250000 fd on
+ *   $ ip link set can3 up type can bitrate 125000 dbitrate 250000 fd on
+ *
+ *   # CAN_1 link
+ *   $ ip link set can1 up type can bitrate 125000 dbitrate 250000 fd on
+ *   $ ip link set can2 up type can bitrate 125000 dbitrate 250000 fd on
+ *
+ * - Perform CAN test, run each of the pair commands in separate terminals:
+ *   # CAN_0 link
+ *   $ canfdtest -v can0
+ *   $ canfdtest -g -v can3
+ *
+ *   # CAN_1 link
+ *   $ canfdtest -v can1
+ *   $ canfdtest -g -v can2
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/interrupt-controller/irq.h>
+
+/*
+ * PWM1 uses PWM1_B pin configuration for pin GP2_13. This conflicts
+ * with SPI_1 CE_1 signal which is also on pin GP2_13. Disable PWM1
+ * in case this hat is in use.
+ *
+ * In case of a dynamic overlay, pwm1 must be disabled before SPI_1
+ * is probed. Otherwise the latter will fail with -EBUSY due to the
+ * conflicting pin being still in use. Hence place pwm1 node here.
+ */
+&pwm1 {
+	status = "disabled";
+};
+
+&{/} {
+	/* Fixed clock dedicated to SPI CAN on 2-CH CAN FD HAT */
+	clk_can0: clk-ws-2ch-canfd0 {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <40000000>;
+	};
+
+	clk_can1: clk-ws-2ch-canfd1 {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <40000000>;
+	};
+
+	/*
+	 * SPI_1 is operated as GPIO SPI, because MSIOF5 can not be
+	 * muxed on the pins allocated for SPI_1 on this CANFD HAT.
+	 */
+	spi {	/* SPI_1 */
+		compatible = "spi-gpio";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		sck-gpios = <&gpio0 10 0>;		/* CN7 pin 40 */
+		miso-gpios = <&gpio0 9 0>;		/* CN7 pin 35 */
+		mosi-gpios = <&gpio0 12 0>;		/* CN7 pin 38 */
+		cs-gpios = <&gpio2 13 GPIO_ACTIVE_LOW>;	/* CN7 pin 12 */
+		num-chipselects = <1>;
+
+		can@0 {
+			compatible = "microchip,mcp2518fd";
+			reg = <0>;
+			clocks = <&clk_can1>;
+			/* CN7 pin 18 */
+			interrupts-extended = <&gpio1 25 IRQ_TYPE_LEVEL_LOW>;
+			spi-max-frequency = <20000000>;
+		};
+	};
+};
+
+&msiof0 {	/* SPI_0 */
+	#address-cells = <1>;
+	#size-cells = <0>;
+	pinctrl-0 = <&msiof0_pins>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	/*
+	 * Native MSIOF chipselect does not work with MCP2518FD
+	 * because MCP251xFD driver needs to keep the chipselect
+	 * line asserted between transfers. This requirement is
+	 * fulfilled only by using GPIO chipselect.
+	 */
+	cs-gpios = <&gpio1 8 GPIO_ACTIVE_LOW>;
+
+	can@0 {
+		compatible = "microchip,mcp2518fd";
+		reg = <0>;
+		clocks = <&clk_can0>;
+		/* CN7 pin 22 */
+		interrupts-extended = <&gpio1 26 IRQ_TYPE_LEVEL_LOW>;
+		spi-max-frequency = <20000000>;
+	};
+};
+
+&pfc {
+	msiof0_pins: msiof0 {	/* SPI_0 */
+		groups = "msiof0_clk", "msiof0_txd", "msiof0_rxd";
+		function = "msiof0";
+	};
+};
-- 
2.53.0

Hi Marek,

On Wed, 9 Sept 2026 at 17:14, Marek Vasut
<marek.vasut+renesas@mailbox.org> wrote:
> Add a DT overlay to bind the WaveShare 2-Channel Isolated CAN FD
> Expansion HAT on the Retronix R-Car V4H Sparrow Hawk board.
>
> Current device link is at https://www.waveshare.com/2-ch-can-fd-hat.htm
>
> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

> V2: - Drop the unique spi controller node identifier
>     - Switch IRQ to active low
>     - Sort compatible and reg properties
>     - Add "CN7 pin 22" comment
>     - Move pwm1 node to the top and add comment
>     - Rename MSIOF0 PFC node

Thanks for the update!

> --- /dev/null
> +++ b/arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk-ws-2ch-canfd.dtso

> +&{/} {
> +       /* Fixed clock dedicated to SPI CAN on 2-CH CAN FD HAT */
> +       clk_can0: clk-ws-2ch-canfd0 {
> +               compatible = "fixed-clock";
> +               #clock-cells = <0>;
> +               clock-frequency = <40000000>;
> +       };
> +
> +       clk_can1: clk-ws-2ch-canfd1 {
> +               compatible = "fixed-clock";
> +               #clock-cells = <0>;
> +               clock-frequency = <40000000>;
> +       };
> +
> +       /*
> +        * SPI_1 is operated as GPIO SPI, because MSIOF5 can not be
> +        * muxed on the pins allocated for SPI_1 on this CANFD HAT.
> +        */
> +       spi {   /* SPI_1 */

As this lives at the root node, I'd rather change it back to
spi-ws-2ch-canfd while applying, if you don't mind?

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
i.e. will queue in renesas-devel for v7.4, with the above fixed.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

On 9/9/26 5:31 PM, Geert Uytterhoeven wrote:

Hello Geert,

>> +       /*
>> +        * SPI_1 is operated as GPIO SPI, because MSIOF5 can not be
>> +        * muxed on the pins allocated for SPI_1 on this CANFD HAT.
>> +        */
>> +       spi {   /* SPI_1 */
> 
> As this lives at the root node, I'd rather change it back to
> spi-ws-2ch-canfd while applying, if you don't mind?
Please make sure the DT schema check does not complain about it, 
otherwise it is fine, thank you.

-- 
Best regards,
Marek Vasut

On Wed, Sep 9, 2026 at 10:55 AM Marek Vasut <marek.vasut@mailbox.org> wrote:
>
> On 9/9/26 5:31 PM, Geert Uytterhoeven wrote:
>
> Hello Geert,
>
> >> +       /*
> >> +        * SPI_1 is operated as GPIO SPI, because MSIOF5 can not be
> >> +        * muxed on the pins allocated for SPI_1 on this CANFD HAT.
> >> +        */
> >> +       spi {   /* SPI_1 */
> >
> > As this lives at the root node, I'd rather change it back to
> > spi-ws-2ch-canfd while applying, if you don't mind?
> Please make sure the DT schema check does not complain about it,
> otherwise it is fine, thank you.

It does complain:

      1 spi-ws-2ch-canfd (spi-gpio): Unevaluated properties are not
allowed ('#address-cells', '#size-cells', 'can@0' were unexpected)
      1 spi-ws-2ch-canfd (spi-gpio): $nodename:0: 'spi-ws-2ch-canfd'
does not match '^spi(@.*|-([0-9]|[1-9][0-9]+))?$'

The 1st warning is a side effect of the 2nd warning.

"spi-1" like the comment says if just "spi" does not work.

Rob

On 9/16/26 10:49 PM, Rob Herring wrote:
> On Wed, Sep 9, 2026 at 10:55 AM Marek Vasut <marek.vasut@mailbox.org> wrote:
>>
>> On 9/9/26 5:31 PM, Geert Uytterhoeven wrote:
>>
>> Hello Geert,
>>
>>>> +       /*
>>>> +        * SPI_1 is operated as GPIO SPI, because MSIOF5 can not be
>>>> +        * muxed on the pins allocated for SPI_1 on this CANFD HAT.
>>>> +        */
>>>> +       spi {   /* SPI_1 */
>>>
>>> As this lives at the root node, I'd rather change it back to
>>> spi-ws-2ch-canfd while applying, if you don't mind?
>> Please make sure the DT schema check does not complain about it,
>> otherwise it is fine, thank you.
> 
> It does complain:
> 
>        1 spi-ws-2ch-canfd (spi-gpio): Unevaluated properties are not
> allowed ('#address-cells', '#size-cells', 'can@0' were unexpected)
>        1 spi-ws-2ch-canfd (spi-gpio): $nodename:0: 'spi-ws-2ch-canfd'
> does not match '^spi(@.*|-([0-9]|[1-9][0-9]+))?$'
> 
> The 1st warning is a side effect of the 2nd warning.
> 
> "spi-1" like the comment says if just "spi" does not work.
Geert send this fix today:

[PATCH] spi: dt-bindings: Relax node name suffixes again

Maybe that works too ?