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) | ----------
-------------- : ------------------
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
--
2.23.0
