docs/fingerprint: Add links to Linux kernel driver
BRANCH=none
TEST=view in gitiles
@@ -528,6 +528,13 @@ determines the [SKU information][Chrome OS Config SKU] (and thus the
[fingerprint config][Chrome OS Config fingerprint]) from [CBI Info]. The SKU for
a given device can be found by viewing `chrome://system/#platform_identity_sku`.
+## Kernel Driver
+
+The kernel driver responsible for handling communication between the AP and
+FPMCU is called [`cros_ec`] and is enabled with [`CONFIG_CROS_EC`] in the Linux
+kernel. FPMCUs that are connected via SPI use [`cros_ec_spi.c`], while FPMCUs
+that are connected via UART use [`cros_ec_uart.c`].
+
[`common/fpsensor`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/common/fpsensor/
[`driver/fingerprint`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/driver/fingerprint
[`nocturne_fp`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/board/nocturne_fp/
@@ -591,3 +598,7 @@ a given device can be found by viewing `chrome://system/#platform_identity_sku`.
[regenerate the config]: https://chromium.googlesource.com/chromiumos/config/+/HEAD/README.md#making-configuration-changes-for-your-project
[`CLFactory`]: https://chromium.googlesource.com/chromiumos/config/+/HEAD/README.md#making-bulk-changes-across-repos
[Fingerprint MCU RAM and Flash]: ./fingerprint-ram-and-flash.md
+[`CONFIG_CROS_EC`]: https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/third_party/kernel/upstream/drivers/platform/chrome/Makefile;l=11;drc=a4e493ca59115fc0692151c1818e5aadf0e79ad0
+[`cros_ec`]: https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/third_party/kernel/upstream/drivers/platform/chrome/cros_ec.c
+[`cros_ec_spi.c`]: https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/third_party/kernel/upstream/drivers/platform/chrome/cros_ec_spi.c
+[`cros_ec_uart.c`]: https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/third_party/kernel/upstream/drivers/platform/chrome/cros_ec_uart.c
