Hi, This is the proposal for USB PD character devices that we could use to communicate USB PD messages directly with the USB PD capable partners, ports and cable plugs from user space. Originally I proposed this idea here as a better way to get the PDOs from the partners (and ports and plugs): https://lkml.org/lkml/2021/10/8/331 Initially you could read the PDOs with this, but it of course is not only limited to PDOs - any messages should potentetially be suported. This is in any case really just a draft, and most likely does not work if you try it, but it should give an idea about what I'm proposing (hopefully). In this proposal I'm placing each device that you can have behind a single USB PD capable Type-C port (so port, partner and plugs) under its own folder, so you would end up with something like this if also both plugs are supported: /dev/pd0/port /dev/pd0/plug0 /dev/pd0/plug1 /dev/pd0/partner I'm also including an ugly test tool that you can try out to dump the PDOs depending on the role of the device - tools/usb/pd-test.c. This is what I got from a charger (and the port at the same time): % pd-test /dev/pd0/port Sink Capabilities: PDO1: 0x3601912c PDO2: 0x000640e1 PDO3: 0x9901912c % pd-test /dev/pd0/partner Source Capabilities: PDO1: 0x0801912c PDO2: 0x0003c12c But please note that this whole series is really just meant to be PoC! Don't assume it will work! The core code that adds the character devices is here: drivers/usb/typec/pd-dev.c. It's actually really simple, and I don't think it would ever need to be much more complicated than that. Example driver support I added to UCSI: drivers/usb/typec/ucsi/pd-dev.c thanks, Heikki Krogerus (4): usb: pd: uapi header split usb: typec: Character device for USB Power Delivery devices usb: typec: ucsi: Add support for PD cdev tools: usb: Hideous test tool for USB PD char device .../userspace-api/ioctl/ioctl-number.rst | 1 + drivers/usb/typec/Makefile | 2 +- drivers/usb/typec/class.c | 42 ++ drivers/usb/typec/class.h | 4 + drivers/usb/typec/pd-dev.c | 210 ++++++++ drivers/usb/typec/pd-dev.h | 15 + drivers/usb/typec/ucsi/Makefile | 2 +- drivers/usb/typec/ucsi/pd-dev.c | 125 +++++ drivers/usb/typec/ucsi/ucsi.c | 37 +- drivers/usb/typec/ucsi/ucsi.h | 7 + include/linux/usb/pd.h | 487 +---------------- include/linux/usb/pd_dev.h | 22 + include/linux/usb/typec.h | 8 + include/uapi/linux/usb/pd.h | 496 ++++++++++++++++++ include/uapi/linux/usb/pd_dev.h | 55 ++ tools/usb/Build | 1 + tools/usb/Makefile | 8 +- tools/usb/pd-test.c | 123 +++++ 18 files changed, 1147 insertions(+), 498 deletions(-) create mode 100644 drivers/usb/typec/pd-dev.c create mode 100644 drivers/usb/typec/pd-dev.h create mode 100644 drivers/usb/typec/ucsi/pd-dev.c create mode 100644 include/linux/usb/pd_dev.h create mode 100644 include/uapi/linux/usb/pd.h create mode 100644 include/uapi/linux/usb/pd_dev.h create mode 100644 tools/usb/pd-test.c -- 2.33.0
