Audio System + Drivers (#562)

Drivers/aw9523b-module/README.md

@@ -0,0 +1,15 @@
+# AW9523B I/O expander
+
+A driver for the `AW9523B` 16-bit I2C-bus I/O expander with LED driver, by Awinic.
+Exposes both 8-bit ports (P0/P1) as 16 GPIO pins (0-15, port 0 = pins 0-7, port 1 =
+pins 8-15) via the `GPIO_CONTROLLER_TYPE` API. P0 is switched to push-pull mode on
+start (every known board wiring for this chip expects push-pull output, not the
+open-drain default).
+
+It does not support pull-up/down resistors, high-impedance outputs, or interrupts;
+requesting those returns `ERROR_NOT_SUPPORTED`. LED driver functionality is not
+implemented.
+
+See https://www.awinic.com/en/productDetail/AW9523B
+
+License: [Apache v2.0](LICENSE-Apache-2.0.md)