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[212.71.14.70]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a027735be1sm99557875e9.11.2026.10.02.03.24.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Oct 2026 03:24:27 -0700 (PDT) From: Sander Speetjens To: Alexandre Belloni Cc: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Florian Fainelli , Jonathan Bell , Stefan Wahren , linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, sander.speetjens@gmail.com, pbrobinson@gmail.com, Conor Dooley , Krzysztof Kozlowski Subject: [PATCH v10 2/3] dt-bindings: rtc: Add property for Raspberry Pi 5 RTC Date: Fri, 2 Oct 2026 12:24:18 +0200 Message-ID: <20261002102419.830595-3-sander.speetjens@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20261002102419.830595-1-sander.speetjens@gmail.com> References: <20261002102419.830595-1-sander.speetjens@gmail.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The Raspberry Pi 5 has a built-in RTC that can be battery-backed via the VBAT pin. When a rechargeable coin cell is used, the hardware requires a trickle-charge voltage to keep the battery topped up. Expose the trickle-voltage-millivolt DT property so the driver can program the correct charge voltage for board specific configurations with the attached battery. The property is added to the existing raspberrypi,bcm2835-firmware binding (rather than creating a new RTC node) because the RTC is accessed exclusively through the firmware mailbox interface. We only $ref the individual property from rtc.yaml and do not reference the full schema, because the firmware node name does not match the $nodename pattern required by rtc.yaml. Acked-by: Conor Dooley Acked-by: Krzysztof Kozlowski Signed-off-by: Sander Speetjens --- V9 -> V10: No changes V8 -> V9: No changes V7 -> V8: No changes V6 -> V7: No changes V5 -> V6: No changes V4 -> V5: As discussed with Conor Dooley, the reff to uint32 is removed and a PR is made on dt-schema adding millivolt to property-units.yaml V3 -> V4: Add a reff to uint32 V2 -> V3: Fixed the firmware property naming V1 -> V2: As discussed with Krzysztof Kozlowski, this property is folded into the existing raspberrypi,bcm2835-firmware properties. .../bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml index 983ea80eaec9..dc71fd57834e 100644 --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml @@ -133,6 +133,11 @@ properties: required: - compatible + trickle-voltage-millivolt: + $ref: /schemas/rtc/rtc.yaml#/properties/trickle-voltage-millivolt + minimum: 1300 + maximum: 5000 + required: - compatible - mboxes @@ -144,6 +149,7 @@ examples: firmware { compatible = "raspberrypi,bcm2835-firmware", "simple-mfd"; mboxes = <&mailbox>; + trickle-voltage-millivolt = <3300>; firmware_clocks: clocks { compatible = "raspberrypi,firmware-clocks"; -- 2.55.0