Hello, This series is an attempt to revive support for pinmuxed I2C0 on the Raspberry Pi BCM2711-based board. On BCM2711-based boards, the I2C0 controller can be muxed between pins 0+1 or 44+45. The former is exposed through the 40-pins GPIO connector, and the latter is used for the RTC on the CM4 I/O board, but also routed to the display and camera connectors on the Raspberry Pi 4B board. The other BCM2711-based board, the Raspberry Pi 400, does not expose or connect anything to pins 44+45. A previous version was posted ([1]) a year and a half ago by Uwe. It bundled the pinmuxing and RTC in a single patch, with the mux added to the CM4 I/O board device tree. This version splits this in two, and moves the pinumxing to the bcm2711-rpi.dtsi to also support the Raspberry Pi 4B. The Raspberry Pi downstream kernel has a more complex DT architecture in order to support different I2C0 pinmuxing for other boards. Two files, bcm283x-rpi-i2c0mux_0_28.dtsi and bcm283x-rpi-i2c0mux_0_44.dtsi, define the two I2C0 pinxmuxing options (pins 0+1 and 28+29, or pins 0+1 and 44+45). Each board .dts then includes the appropriate file. I'm hoping to avoid this additional complexity for now, by addressing the I2C0 pinmuxing for BCM2711-based boards only. If/when support for I2C0 pinmuxing on boards will be needed, we can revisit this topic. Compared to the Raspberry Pi downstream kernel, the two muxed I2C buses are labelled i2c0_0 and i2c0_1 instead of i2c0 and i2c_csi_dsi. This change was made to keep the naming of the I2C controller labels consistent, avoiding renaming of the I2C0 controller's label from i2c0 to i2c0if. Dave, are you fine with the differences between this patch series and the downstream kernel, or do you expect them to cause issues ? [1] https://lore.kernel.org/linux-arm-kernel/20211231115109.94626-1-uwe@xxxxxxxxxxxxxxxxx/ Uwe Kleine-König (2): ARM: dts: bcm2711-rpi: Add pinctrl-based multiplexing for I2C0 ARM: dts: bcm2711-rpi-cm4-io: Add RTC on I2C0 arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts | 16 ++++++++++++ arch/arm/boot/dts/bcm2711-rpi.dtsi | 31 ++++++++++++++++++++++++ 2 files changed, 47 insertions(+) -- Regards, Laurent Pinchart
