Hi, On 16/02/2020 18:21, Noralf Trønnes wrote: > Hi, > > A while back I had the idea to turn a Raspberry Pi Zero into a $5 > USB to HDMI/SDTV/DSI/DPI display adapter. > > Thinking about how to represent the display to the driver I realised > that hardware use registers as API. And Linux does have a generic > register abstraction: regmap. Furthermore this means that if I can do a > regmap over USB implementation, it will be easy to do other functions > like gpio, adc and others. After a few iterations trying to understand > the USB subsystem and satisfying driver requirements, I now have > something that looks promising. > > I'm sending out an early version hoping to get feedback especially on > the core parts that handles regmap and interrupts. > > Overview: > > USB Host : USB Device > : > -------------- : ------------------ > ---------- | mfd: mud | : | f_mud | ---------- > | Driver | -------------- : | | | Driver | > ---------- | regmap-usb | : | (mud_regmap) | ---------- > -------------- : ------------------ > The idea is really like ARA's greybus, but much simpler ! Anyway nice idea, do you have good performance over USB2 and RPi's awful DWC2 gagdet controller ? Neil > > I've attached 2 drivers: > - gpio/pinctrl: is more or less finished > - display: needs a lot more work > > > USB3 device > I've only tested this with usb2 devices (Pi, BBB) so I should get myself > a usb3 gadget capable board. My searching didn't turn up much, so this > seems to be quite rare. ROCK960 has USB 3.0 type C OTG but the price is > $139 which is a bit expensive for this hobby project. Does anyone know > of a cheap board? > > Noralf. > > > Noralf Trønnes (9): > regmap: Add USB support > mfd: Add driver for Multifunction USB Device > usb: gadget: function: Add Multifunction USB Device support > pinctrl: Add Multifunction USB Device pinctrl driver > usb: gadget: function: mud: Add gpio support > regmap: Speed up _regmap_raw_write_impl() for large buffers > drm: Add Multifunction USB Device display driver > drm/client: Add drm_client_init_from_id() and drm_client_modeset_set() > usb: gadget: function: mud: Add display support > > drivers/base/regmap/Kconfig | 8 +- > drivers/base/regmap/Makefile | 1 + > drivers/base/regmap/regmap-usb.c | 1026 ++++++++++++++++++ > drivers/base/regmap/regmap.c | 10 +- > drivers/gpu/drm/Kconfig | 2 + > drivers/gpu/drm/Makefile | 1 + > drivers/gpu/drm/drm_client.c | 37 + > drivers/gpu/drm/drm_client_modeset.c | 52 + > drivers/gpu/drm/mud/Kconfig | 18 + > drivers/gpu/drm/mud/Makefile | 4 + > drivers/gpu/drm/mud/mud_drm.c | 1198 ++++++++++++++++++++++ > drivers/gpu/drm/mud/mud_drm.h | 137 +++ > drivers/gpu/drm/mud/mud_drm_gadget.c | 889 ++++++++++++++++ > drivers/mfd/Kconfig | 8 + > drivers/mfd/Makefile | 1 + > drivers/mfd/mud.c | 580 +++++++++++ > drivers/pinctrl/Kconfig | 9 + > drivers/pinctrl/Makefile | 1 + > drivers/pinctrl/pinctrl-mud.c | 657 ++++++++++++ > drivers/pinctrl/pinctrl-mud.h | 89 ++ > drivers/usb/gadget/Kconfig | 36 + > drivers/usb/gadget/function/Makefile | 6 + > drivers/usb/gadget/function/f_mud.c | 913 +++++++++++++++++ > drivers/usb/gadget/function/f_mud.h | 210 ++++ > drivers/usb/gadget/function/f_mud_drm.c | 181 ++++ > drivers/usb/gadget/function/f_mud_pins.c | 962 +++++++++++++++++ > drivers/usb/gadget/function/mud_regmap.c | 936 +++++++++++++++++ > include/drm/drm_client.h | 4 + > include/linux/mfd/mud.h | 16 + > include/linux/regmap.h | 23 + > include/linux/regmap_usb.h | 97 ++ > 31 files changed, 8107 insertions(+), 5 deletions(-) > create mode 100644 drivers/base/regmap/regmap-usb.c > create mode 100644 drivers/gpu/drm/mud/Kconfig > create mode 100644 drivers/gpu/drm/mud/Makefile > create mode 100644 drivers/gpu/drm/mud/mud_drm.c > create mode 100644 drivers/gpu/drm/mud/mud_drm.h > create mode 100644 drivers/gpu/drm/mud/mud_drm_gadget.c > create mode 100644 drivers/mfd/mud.c > create mode 100644 drivers/pinctrl/pinctrl-mud.c > create mode 100644 drivers/pinctrl/pinctrl-mud.h > create mode 100644 drivers/usb/gadget/function/f_mud.c > create mode 100644 drivers/usb/gadget/function/f_mud.h > create mode 100644 drivers/usb/gadget/function/f_mud_drm.c > create mode 100644 drivers/usb/gadget/function/f_mud_pins.c > create mode 100644 drivers/usb/gadget/function/mud_regmap.c > create mode 100644 include/linux/mfd/mud.h > create mode 100644 include/linux/regmap_usb.h >
