Device tree RTC node for Viola

Technical Support
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1

I might be overlooking it, but found device tree files for Aster, Iris but not for Viola. Managed to put most of it together using those mentioned earlier but haven’t found the node for the RTC…

Could someone point me in the right direction?

2

Hi, I’m the Toradex AI Assistant. I’m in early beta, and I would appreciate your feedback.
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Hello,

For integrating an RTC node into the device tree for the Viola carrier board, you would typically start by identifying if the Viola board uses a specific Real-Time Clock (RTC) chip that is different from those used in the Aster or Iris carrier boards. If the RTC chip is the same or similar, you can often reuse or adapt the device tree node from those boards with minor modifications.

The device tree node for an RTC typically looks something like this:

&i2c1 {
    rtc@68 {
        compatible = "maxim,ds3231";
        reg = <0x68>;
    };
};

This example assumes an I2C-based RTC, specifically a Maxim DS3231, connected to the first I2C bus (i2c1) at address 0x68. The compatible property should match the RTC chip used on your Viola board. The reg property specifies the I2C address of the device.

If the Viola board uses a different RTC chip, you’ll need to adjust the compatible string to match the chip used. You can find the correct compatible string in the Linux kernel documentation under the Documentation/devicetree/bindings/rtc directory or by looking up the specific RTC chip documentation.

If the Viola does not have a dedicated RTC chip and relies on the SoC’s internal RTC, you might not need to add an RTC node in the device tree specifically for the Viola board. Instead, ensure that the SoC’s RTC is correctly enabled in the device tree for the SoC you are using.

Without specific details on the RTC used by the Viola board, this is a general guideline. If the Viola board uses a unique RTC not covered by the Aster or Iris examples, you might need to refer to the RTC chip’s datasheet for the correct device tree configuration.

Best regards, Toradex AI Assistant

Please, also check if these links can help you solve your problem:

Reference Designs | Toradex Developer Center.

3

Though the external RTC circuit pads are available on the Viola carrier board, none of the external RTC components are assembled. However, the schematic for these pads is similar to that of the Iris or Colibri Development board. Therefore, you can use the RTC node from their device tree files.

&i2c4 {
	status = "okay";

	/* M41T0M6 real time clock on carrier board */
	rtc: m41t0m6@68 {
		compatible = "st,m41t0";
		reg = <0x68>;
	};
};
4

Thanks thought I started from one of those device trees, guess I didn’t…
Furthermore, I’m using the plus variant of the viola which does have those components assembled.