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diff --git a/docs/zephyr/zephyr_usba.md b/docs/zephyr/zephyr_usba.md new file mode 100644 index 0000000000..ce66125905 --- /dev/null +++ b/docs/zephyr/zephyr_usba.md @@ -0,0 +1,78 @@ +# Zephyr USBA Configuration + +[TOC] + +## Overview + +[USBA] is used to configure the number of USB Type-A ports in the system and +optional control of the power supplied by said ports. + +## Kconfig Options + +`CONFIG_PLATFORM_EC_USBA` enables support for USB-A ports in the EC application. +Refer to [Kconfig.usba] for all sub-options controlling USB-A ports. + +## Devicetree Nodes + +By default, for each USB Type-A port, a GPIO pin is required to control when power +is supplied to the port. The GPIO pins are described in Device Tree nodes. + +Refer to the [named-gpios.yaml] and [cros-ec,usba-port-enable-pins.yaml] child-binding +files for details about gpio properties. + +## Board Specific Code + +none + +## Threads + +When `CONFIG_PLATFORM_EC_USB_PORT_POWER_DUMB=y`, then the EC application automatically +powers up USB-A ports when the AP chipset starts up and powers off the USB-A ports +when the AP chipset shuts down. + +## Testing and Debugging + +Use the gpioset console command to manually enable and disable the USB Type-A port power. + +`gpioset` usage: gpioset <pin_name> <0 | 1> + +The `usbchargemode` console command is used to enable and disable charging +from the USB Type-A port. + +* For dumb power ports: `usbchargemode` <port> <on | off> +* For smart power ports: `usbchargemode` <port> <0 | 1 | 2 | 3> <0 | 1> + +Charging from USB Type-A ports can be controlled from the AP using ectool `usbchargemode`. + +`ectool usbchargemode` <port> <disabled | SDP | CDP | DCP> [inhibit_charge] + +Refer to the Application Processor to EC communication for more information about using[ ectool]. + +## Example + +The Herobrine board has one USB Type-A port: + +The following configures the project for one port. + +``` +`CONFIG_PLATFORM_EC_USB_PORT_POWER_DUMB=y` +``` + +The following device tree node configures the gpio pin. + +``` +gpio_en_usb_a_5v: en_usb_a_5v { + gpios = <&gpiof 0 GPIO_OUT_LOW>; +}; + +usba-port-enable-list { + compatible = "cros-ec,usba-port-enable-pins"; + enable-pins = <&gpio_en_usb_a_5v>; +}; +``` + +[USBA]: ../ec_terms.md#usba +[Kconfig.usba]: https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/platform/ec/zephyr/Kconfig.usba +[named-gpios.yaml]: ../../zephyr/dts/bindings/gpio/named-gpios.yaml +[cros-ec,usba-port-enable-pins.yaml]: ../../zephyr/dts/bindings/gpio/cros-ec,usba-port-enable-pins.yaml +[ectool]: https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/platform/ec/util/ectool.c;?q=function:ms_help&ss=chromiumos |