Intel Linux Driver Orphaned For Limiting RF Exposure To Humans

Over the past year and a half a number of open-source drivers in the Linux kernel have been orphaned as a result of departures from the company. The impact has ranged from the Intel CPU "coretemp" temperature driver being orphaned without a maintainer to other lesser known Intel drivers. Another lesser known Intel driver is now being orphaned with no longer having a maintainer at the company: the Intel Specific Absorption Rate Driver. The Intel Specific Absorption Rate "SAR" Driver is controlled via the INTEL_SAR_INT1092 Kconfig option and is used to limit the exposure of the human body to radio frequency (RF) from Intel M.2 modems. The kernel driver regulates the RF power based on the SAR data supplied by the BIOS over ACPI via hardware sensors. It then depends upon a user-space allocation for reading the device attributes, SAR table index, device position, etc, and ultimately is all collected and analyzed to dynamically adjust the RF power regulation to limit RF exposure to humans. This driver supports WWAN modems with the "INTC1092" device ID. The Intel SAR driver was added to the Linux kernel back in Linux 5.15 in 2021. This Intel int1092 driver code has seen a handful of fixes this year thanks to code defects found by the likes of Sashiko plus touched during various tree-wide kernel changes. With the former maintainer of the driver no longer working at Intel plus Intel having exited the modem business years ago, the Linux driver is now being marked as an orphan. It will still live within the Linux kernel for anyone still using Dynamic SAR for regulatory reasons with a INTC1092-equipped Intel laptop but not actively being supported.