Hi Sam,
(stumbled on this accidentally)
On Thu, Aug 2, 2018 at 9:46 PM Sam Ravnborg <sam@xxxxxxxxxxxx> wrote:
> The pardata supports implement a simple bus for devices
> that are connected using a parallel bus driven by GPIOs.
> The is often used in combination with simple displays
> that is often seen in older embedded designs.
> There is a demand for this support also in the linux
> kernel for HW designs that uses these kind of displays.
>
> The pardata bus uses a platfrom_driver that when probed
> creates devices for all child nodes in the DT,
> which are then supposed to be handled by pardata_drivers.
>
> Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
> --- /dev/null
> +++ b/Documentation/driver-api/pardata.rst
> @@ -0,0 +1,60 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +=========================
> +Parallel Data Bus/Drivers
> +=========================
> +
> +Displays may be connected using a simple parallel bus.
> +This is often seen in embedded systems with a simple MCU, but is also
> +used in Linux based systems to a small extent.
> +
> +The bus looks like this:
> +
> +.. code-block:: none
> +
> + ----+
> + | DB0-DB7 or DB4-DB7 +----
> + ===/========================
> + | E - enable | D
> + ---------------------------- I
> + C | Reset | S
> + P ---------------------------- P
> + U | Read/Write (one or two) | L
> + ---------------------------- A
> + | RS - instruction/data | Y
> + ----------------------------
> + | +----
> + ----+
Oh, cool! Looks like this can be used by the hd44780 driver.
Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt
drivers/auxdisplay/hd44780.c
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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