I know [1], but there might be other subsystems doing the same thing.
[1]https://urldefense.proofpoint.com/v2/url?u=https-3A__elixir.bootlin.com_linux_v4.20-2Drc3_source_drivers_spi_spidev.c&d=DwIFaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=qVuU64u9x77Y0Kd0PhDK_lpxFgg6PK9PateHwjb_DY0&m=S_YF5FjfGFFGFa7x6nHrT6npsIFjUbYRorSANaPpaiI&s=xXnwGBSGrVxandwp6biURmXq-85iMMLd8-n2McDsIWY&e=