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[212.71.14.70]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4870bf27ce2sm15276567f8f.20.2026.09.17.05.25.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 05:25:13 -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 Subject: [PATCH v2 0/2] Raspberry Pi 5 RTC driver Date: Thu, 17 Sep 2026 14:21:42 +0200 Message-ID: <20260917122144.703221-1-sander.speetjens@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The Raspberry Pi 5 has a battery-backed RTC located on the DA9091 PMIC accessed via the I2C bus[1]. Access to the RTC is provided exclusively through the VideoCore firmware mailbox interface (not via a direct I2C register interface). As stated by jamesh on the Rasperry Pi forum [2], "There are no plans to release a public datasheet for the DA9091." So we are stuck with the firmware interface for now. PhilE also states that "The firmware needs full control of the DA9091, sometimes with extremely low latency, otherwise there's a risk the supply could just cut the power." This series adds: - a DT property for the charging voltage of the RTC battery - the RTC driver that talks to the firmware The driver and binding are based on (and largely taken from) the downstream Raspberry Pi kernel. The main changes for upstream are the addition of a dt binding property for setting the charging voltage and binding the driver from the raspberrypi-firmware driver instead of from the DT. The driver supports time read/write, alarm, and optional trickle charging voltage configuration via the device-tree. Testing ------- - Hardware: Raspberry Pi 5 Model B revC - Kernel: v7.2 - dt_binding_check: passed - Basic RTC operations (read/write time, alarm) verified [1] https://www.raspberrypi.com/news/introducing-raspberry-pi-5/ [2] https://forums.raspberrypi.com/viewtopic.php?t=359073 Sander Speetjens (2): dt-bindings: rtc: Add property for Raspberry Pi 5 RTC rtc: Add Raspberry Pi 5 RTC driver .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 7 + drivers/firmware/raspberrypi.c | 19 ++ drivers/rtc/Kconfig | 11 + drivers/rtc/Makefile | 1 + drivers/rtc/rtc-raspberrypi.c | 277 ++++++++++++++++++ 5 files changed, 315 insertions(+) create mode 100644 drivers/rtc/rtc-raspberrypi.c base-commit: fd73f4a6659897191fa0d40695fe370925dd3780 -- 2.55.0