Date: Mon, 24 Jun 2019 15:06:21 +0100 From: Kaya Saman <kayasaman@optiplex-networks.com> To: Milan Obuch <milan@obuch.sk> Cc: freebsd-arm@freebsd.org Subject: Re: Pine64-LTS and UART ports Message-ID: <d0719fbf-b4d5-aec7-bcad-1a9157b63e69@optiplex-networks.com> In-Reply-To: <20190624133017.5a9689b7@zeta.dino.sk> References: <371fe0f0-9f91-e4ba-ff4e-8338fe9d63de@optiplex-networks.com> <20190623235732.4439b707@zeta.dino.sk> <ae92ac02-ce53-18fe-9eab-8b17e8d52cd2@optiplex-networks.com> <20190624133017.5a9689b7@zeta.dino.sk>
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On 6/24/19 12:30 PM, Milan Obuch wrote: > On Mon, 24 Jun 2019 10:59:26 +0100 > Kaya Saman <kayasaman@optiplex-networks.com> wrote: > >> On 6/23/19 10:57 PM, Milan Obuch wrote: >>> On Sun, 23 Jun 2019 21:42:16 +0100 >>> Kaya Saman <kayasaman@optiplex-networks.com> wrote: >>> =20 >>>> Hi, >>>> >>>> I've attached an RS232c converter board to UART2 on my Pine64-LTS >>>> board. I followed the pinout diagrams from here: >>>> =20 >>> [ snip - no comment on this all ] >>> =20 >>>> Based on my reading I created a 'hints' file for it: >>>> >>>> /boot/device.hints >>>> hint.uart.2.disabled=3D"0" >>>> >>>> but I'm not sure if this is correct? >>>> =20 >>> Hi, >>> >>> short comment - in arm world, there is no device.hints file used, >>> it is moved into dtb file. You should use overlay to enable uart2, >>> which will then be used in /boot/loader.conf file - there should be >>> line >>> >>> fdt_overlays=3D"sun50i-a64-sid,sun50i-a64-ths,sun50i-a64-timer,sun50i= -a64-opp" >>> >>> I did not tried it myself yet, so I can't write exactly what to use, >>> important part in dtso file you should create is >>> >>> &uart2 { status =3D "okay"; >>> } >>> >>> because uart2 is disabled in shipped dtb. Look in dts overlays >>> directories for some examples, maybe you could search in this >>> mailing list archive, too... or someone with more knowledge could >>> tell more. >>> >>> Regards, >>> Milan >> >> Thanks Milan for the tip!! >> >> >> I am now going through these links: >> >> https://forums.freebsd.org/threads/fdt-overlays-in-freebsd.52530/ >> >> http://freebsd.1045724.x6.nabble.com/Allwinner-dtb-overlays-on-CURRENT= -Also-flashrom-SPI-td6271021.html >> >> >> There doesn't seem to be too much information on how to create the >> Overlays. I found the .dtso files in the /usr/src/sys directory so I >> am guessing that one needs to compile the Overlays into the kernel? >> > In order to create an overlay, I found simple way to do it using > antrastructure already presented in out source tree... > > First, you need to create overlay source file. Other overlays for arm64 > devices are located in /usr/src/sys/dts/arm64/overlays directory, so I > put sun50i-a64-uart2.dtso file there too. See attachment - all it does > is just enabling uart2. Everything else is already present in dtb. > > Then you need compile this overlay. You could invoke dtc manually, it > is not hard, but easier is using infrastructure - I just did > > cd /usr/src/sys/dts/arm64/overlays > make > > and all overlays are created. Observe the output messages. > > Now you need to install overlay for uart2. > > cp /tmp/sun50i-a64-uart2.dtbo /boot/dtb/overlays/ > > I compared files in /tmp and /boot/dtb/overlays directories just to be > sure I am not far off, all corresponding files were the same size. > > Last step, activate this overlay. In /boot/loader.conf, change line > > fdt_overlays=3D"sun50i-a64-sid,sun50i-a64-ths,sun50i-a64-timer,sun50i-a= 64-opp" > > to > > fdt_overlays=3D"sun50i-a64-sid,sun50i-a64-ths,sun50i-a64-timer,sun50i-a= 64-opp,sun50i-a64-uart2" > > That's it. Now reboot. You should see > > applying DTB overlay '/boot/dtb/overlays/sun50i-a64-uart2.dtbo' > > message on the very start of boot process, and later > > uart1: <16750 or compatible> mem 0x1c28800-0x1c28bff irq 33 on simplebu= s0 > uart1: fast interrupt > uart1: PPS capture mode: DCD > > After boot finishes, you should find now /dev/cuau1 file in addition > to /dev/cuau0 present from the start. You should be able to use > > cu -l /dev/cuau1 -s 115200 > > (or other speed as necessary) to communicate with device connected to > uart2 port. Notice the numbering - as we did not enable physical uart1 > port, it is skipped when attaching drivers, so physical port uart2 is > numbered as uart1 device, thus creating cuau1 entry in dev directory. > If you decide to use physical port uart1, exactly the same method > should work, then numbering devices and physical ports would match. > > Hope this helps. It is not rocket science, and if all you need is just > enable the device already present in dtb with right bindings, it is > really simple. Yep, I think I have a handle on things now. I will try this soon :-)=20 Many thanks for this! > > One additional note - in your original mail you are mentioning PPS_SYNC > in kernel. Off top of my head, if you would like to connect GPS > receiver with PPS output to get precise time source, you need either > serial port with modem control lines or an additional GPIO pin. I did > not look for the details, but I think uart2 port on Pine is just three > wires, so the latter is actually the case, and you need gpiopps driver > as well. I did not work with this yet, so I can't comment on this > issue. Just pointer to another overlay source: > > https://github.com/raspberrypi/linux/blob/rpi-4.9.y/arch/arm/boot/dts/o= verlays/pps-gpio-overlay.dts > > Regards, > Milan Yes, the GPS receiver will connect to the CTS port on UART2. From the=20 link in my original post that is Pin E27 on the Euler bus. I have currently tested this with the USB serial adapter (yes high=20 latency but just for testing), from the ucom man page: =A0=A0=A0=A0=A0=A0=A0=A0 1=A0=A0=A0=A0 Capture pulses on the CTS line. =A0=A0=A0=A0=A0=A0=A0=A0 2=A0=A0=A0=A0 Capture pulses on the DCD line. So then it is just a matter of adding: hw.usb.ucom.pps_mode=3D1 into the=20 /boot/loader.conf. Of course this is for USB ;-) Regards, Kaya
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