Add magnetometer Yamaha YAS537 to the DeviceTree of samsung-serranove. The YAS537 variant was recently added to the Yamaha YAS magnetometers driver [1]. In the DeviceTree of samsung-serranove for the Android kernel, there is unfortunately no information on interrupts or pinctrl [2]. In the Android kernel driver for magnetometer Yamaha YAS537, there is a device-specific matrix to correct an ellipsoid shape of the measure values into a sphere shape [3]. This could be converted and applied to a mount-matrix. However, the current state of the mainline Yamaha YAS537 driver needs post-process calibration in userspace anyway, as it lacks a formula to center the measure values around zero. The correction of the ellipsoid into a sphere can be done in the post-process calibration as well. A mount-matrix is needed nonetheless. When putting samsung-serranove flat on a table in portrait orientation heading north, the Yamaha YAS537 magnetometer axes natively point X+ to north, Y+ to east and Z+ into the ground, which corresponds to a common way to define the Earth's magnetic field coordinate system [4]. According to the IIO definition, it should be Y+ to north, X+ to east and Z+ upwards [5], which corresponds to a common device coordinate system and eases sensor fusing. [1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/iio/magnetometer/yamaha-yas530.c?id=65f79b501030678393eae0ae03d60a8151fbef55 [2] https://github.com/msm8916-mainline/android_kernel_qcom_msm8916/blob/GT-I9195I/arch/arm/boot/dts/samsung/msm8916/msm8916-sec-serranovelte-eur-r03.dtsi#L318-L321 [3] https://github.com/msm8916-mainline/android_kernel_qcom_msm8916/blob/GT-I9195I/drivers/iio/magnetometer/yas_mag_drv-yas537.c#L105-L106 [4] https://en.wikipedia.org/wiki/Earth%27s_magnetic_field#Characteristics [5] https://github.com/torvalds/linux/blob/v5.19/Documentation/devicetree/bindings/iio/mount-matrix.txt#L93-L126 Cc: Stephan Gerhold <stephan@xxxxxxxxxxx> Signed-off-by: Jakob Hauser <jahau@xxxxxxxxxxxxxx> --- arch/arm64/boot/dts/qcom/msm8916-samsung-serranove.dts | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/arm64/boot/dts/qcom/msm8916-samsung-serranove.dts b/arch/arm64/boot/dts/qcom/msm8916-samsung-serranove.dts index 439e89cf7878..bbd6bb3f4fd7 100644 --- a/arch/arm64/boot/dts/qcom/msm8916-samsung-serranove.dts +++ b/arch/arm64/boot/dts/qcom/msm8916-samsung-serranove.dts @@ -210,6 +210,15 @@ imu@6b { pinctrl-names = "default"; pinctrl-0 = <&imu_irq_default>; }; + + magnetometer@2e { + compatible = "yamaha,yas537"; + reg = <0x2e>; + + mount-matrix = "0", "1", "0", + "1", "0", "0", + "0", "0", "-1"; + }; }; &blsp_i2c4 { -- 2.35.1
