Den 18.02.2020 21.57, skrev Andy Shevchenko: > On Sun, Feb 16, 2020 at 7:30 PM Noralf Trønnes <noralf@xxxxxxxxxxx> 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) | ---------- >> -------------- : ------------------ >> >> >> I've attached 2 drivers: >> - gpio/pinctrl: is more or less finished >> - display: needs a lot more work > > Can regmap-usb be used for drivers/mfd/dln2.c for example? > No, apparently dln-2 uses custom protocol structs for each function with a common header. regmap-usb is a register abstraction with the ability to bulk read/write multiple registers in one transfer. I see that dln-2 does a lot of what I'm aiming for except that it doesn't have the display part. Noralf.
