The Linux community has developed a kernel driver for this product. There is additional info and links here: https://www.ti.com/tool/AMC6821SW-LINUX
TI doesn't offer source code for this product.
Part Number: AMC6821 Hi there:
customer side would like to check the R.P.M reading of AMC6821 register whether match the real case FAN speed.
But the reading from 0x08 & 0x09 was always 0xff, may we know the how to read the speed correctly?