BBB uarts & pps dts definitions

[Tony Hain]

Ian Lepore wrote:
> On Wed, 2017-01-25 at 16:54 -0800, Tony Hain wrote:
> > Hi,
> >
> > [...]
> >
> > I figured it would be simpler to start debugging with the serial port
> > first since there was an example for the working console port. My
> > original intent was to use uart5 since it was also on P8, but given
> > gpioctl is only listing the first 32 I switched to uart1  (P9-26).
> > Simply changing the "disabled" to "okay" for the uart was sufficient
> > to make it show up as /dev/ttyu1, but not enough to make it work.
> > Taking hints from various dts files for uart1, I
> > have:
> >       uart1_pins:  pinmux_uart1_pins {
> >                 pinctrl-single,pins = <0x180 0x020 0x184 0x0>;
> >                  linux,phandle = <0x1>;
> >                  phandle = <0x1>;
> >         };
> > ...
> >                 serial at 48022000 {
> >                         compatible = "ti,am3352-uart",
> > "ti,omap3-uart";
> >                         ti,hwmods = "uart2";
> >                         clock-frequency = <0x2dc6c00>;
> >                         reg = <0x48022000 0x2000>;
> >                         interrupts = <0x49>; //
> > status = "disabled";
> >                         status = "okay";
> >                         dmas = <0x29 0x1c 0x0 0x29 0x1d 0x0>;
> >                         dma-names = "tx", "rx";
> >
> >                         pinctrl-names = "default";
> >                         pinctrl-0 = <&uart1_pins>;
> >                 };
> > I am getting a duplication error for the phandle lines. I realize the
> > existing devices have unique hex values for those, but the only
> > references search is turning up and downloadable dtb files I can find
> > have the phandle for that uart as 0x1. Is there a reason that all the
> > uarts are not listed with the correct values & commented out in the
> > default DTS? In addition,
> > uart4 & 5 don't have the dma lines that the others have ...  and those
> > lines don't appear in the reference linux dts files so I can't tell
> > what they are for. Comments in the dts hinting at where to look for
> > references for other values would make it easier to clone a working
device
> for another one.
> >
> 
> I don't know anything about the dts overlay stuff, I haven't had time to
learn
> about it yet.
> 
> Back when I was first working on the dmtpps driver, before I made it
> configure the timer input pin for itself, I was just modifying the main
dts
> source in sys/gnu/dts/arm/am335x-boneblack.dts to enable uart1 and
> timer4 for testing.  I'll attach the patch I used to enable them and
configure
> the pins.
> 
> -- Ian

The diff is helpful, but clearly I am going to have to pull down full source
to get the complete definitions. This uses variable names that are not
defined anywhere I can find using search, and they don't appear to be used
in the dtb distributed in /boot/dtb, but that could simply be that backing
the dtb to dts is using the resolved contents of those variables. 

Tony