[PATCH v4 0/6] FUSB302 USB-C controller support

[Marek Vasut]

On 8/30/24 8:22 PM, Sebastian Reichel wrote:
> Hi,
> 
> On ROCK 5B power is usually supplied via it's USB-C port. This port has the
> data lines connected to RK3588, VBUS connected to the input regulator and
> CC pins connected to FUSB302. FUSB302 is a USB-C controller, which can be
> accessed via I2C from RK3588. The USB-C controller is needed to figure out
> the USB-C cable orientation, but also to do USB PD communication. Thus it
> would be great to enable support for it in the operating system.
> 
> But the USB-PD specification requires, that a device reacts to USB-PD messages
> send by the power-supply within around 5 seconds. If that does not happen the
> power-supply assumes, that the device does not support USB-PD. If a device
> later starts sending USB-PD messages it is considered an error, which is solved
> by doing a hard reset. A USB-PD hard reset means, that all supply voltages are
> removed for a short period of time. For boards, which are solely powered
> through their USB-C port, like the Radxa Rock 5B, this results in an machine
> reset. This is currently worked around by not describing the FUSB302 in the
> kernel DT, so nothing will ever speak USB-PD on the Rock 5B. This means
> 
> 1. the USB-C port cannot be used at all
> 2. the board will be running via fallback supply, which provides limited
>     power capabilities
> 
> In order to avoid the hard reset, this adds FUSB302 support to U-Boot, so
> that we react to the power-supply's queries in time. The code, which is
> originally from the Linux kernel, consists of two parts:
> 
> 1. the tcpm state machine, which implements the Type C port manager state
>     machine as described in the USB PD specification
> 2. the fusb302 driver, which knows about specific registers
> 
> Especially the first part has been heavily modified compared to the
> kernel, which makes use of multiple delayed works and threads. For this
> I used a priorly ported version from Rockchip, removed their hacks and
> any states not necessary in U-Boot (e.g. audio accessory support).
> 
> This version has been tested on Radxa Rock 5B using the open source TF-A
> (patches recently got merged into master branch) using the following power
> supplies:
> 
>   * non PD capable (reports 5V 0A)
>   * RavPower 90W (ok)
>   * UGREEN 100W (ok)
>   * Anker 45W (ok)
>   * RavPower PB (hard resets in U-Boot, but succeeds at some point,
>     I still need to investigate)

I am happy with this series, as long as Jonas also says yes, this should 
go into u-boot/next . Thanks !