BMI220 firmware support

[barryblueice]

I bought some cheap BMI270 for personal built SlimeVR Case by myself from a seller from Chinese AliExpress Market, the seller claim that these sensors are BMI270:

But when I solder the sensor on, the SlimeVR tracker detect the sensor reg is 0x26 (BMI270 is 0x24):

After searching from google, I found a similar post on the bosch forum: BMI270 CHIP ID reported as 0x26 instead of 0x24, someone found that 0x26 is actually BMI220:

So I decided to try to adapt the BMI220 for the tracker. Unfortunately, I can't find any information about the source code about the BMI220. But I found the firmware successfully finally from coreboot/chrome-ec, than I try to modified the relatived source code which based on BMI270, now it can work.

However, there may still be bugs, so use them with caution.

The usage should be the same as BMI270/BMI160.

Attention
According from my friends, There is no difference between the BMI270 and BMI220 from the appearance and the sensors marking, and the sensor type can only be determined from the reg code after the sensor is soldered on the PCB.

[l0ud]

Please put new sensor at the end, regardless of alphabetical order, server expects particular ID.

[barryblueice]

Sorry for interrupting, I will change it later

[l0ud]

did you check if advanced stuff like CRT really works (non-zero values returned, unique for each sensor?)

[barryblueice]

According to serial console, it seems like excepting for CRT, other function can work normally.
The CRT function returned all-zero values.
I don't have any source code or datasheet related to BMI220. So I don't know how to modified the CRT function in order to make it work, also I don't know if this is a normal value😂.