Date: Thu, 16 Aug 2018 09:42:28 -0300 From: "Dr. Rolf Jansen" <rj@obsigna.com> To: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: Beaglebone Black pinmuxing Message-ID: <56756FA3-8FD7-44A4-A2D8-054E7C86744B@obsigna.com> In-Reply-To: <13360A40-3381-4AF9-8EC5-C8E9B00CCABD@dons.net.au> References: <13360A40-3381-4AF9-8EC5-C8E9B00CCABD@dons.net.au>
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> Am 15.08.2018 um 23:56 schrieb O'Connor, Daniel <darius@dons.net.au>:
>=20
> Hi,
> I have a BBB with a GPS engine attached to UART4 (P9_11 - UART4 Rx, =
P9_13 - UART4 Tx) but I am having trouble communicating with it.
>=20
> I have tried both an overlay and editing the main DTS file directly =
but while the UART is probed and attached I can't see any data coming =
in, nor see any go out (by putting a 'scope probe on P9_13 while sending =
data out cuau2).
>=20
> By my reading of the TRM and some googling P9_13 is gpmc_wait0 who's =
pinmux offset is 0x870, P9_11 is gpmc_wpn, offset 0x874. The pinmuxes =
get 0x800 subtracted from this (based on what is already in the DTS =
file)
>=20
> This is the overlay source..
> root@generic:/ # cat /boot/dtb/overlays/am335x-beaglebone-uart4a.dtso
> /dts-v1/;
> /plugin/;
>=20
> / {
> compatible =3D "ti,am335x-bone-black", "ti,am335x-bone", =
"ti,am33xx";
>=20
> fragment@1 {
> target =3D <&uart4>;
> __overlay__ {
> status =3D "okay";
> pinctrl-names =3D "default";
> pinctrl-0 =3D <
> 0x074 0x06 // =
gpmc_wpn.uart4_txd_mux2 -> mode 6
> 0x070 0x2e // =
gpmc_wait0.uart4_rxd_mux2 -> mode 6
>> ;
> };
> };
> };
>=20
> Compiled with..
> dtc -@ -I dts -O dtb -o am335x-beaglebone-uart4a.dtbo =
am335x-beaglebone-uart4a.dtso
> And I put this in loader.conf
> fdt_overlays=3D"am335x-beaglebone-uart4a"
Hello,
Only recently I need to pass over all the very same obstacles as you =
need to do now, in order to get a DAC-I2C module enabled and working on =
my BBB. In my case, the curial point was to get the pinmuxing straight =
and correctly linked to the respective I2C node. My BeableBone Black is =
running on FreeBSD 12-ALPHA1. Note, there are major differences in the =
DT between 11 and 12, and therefore depending on your FreeBSD version =
the following hints may not fully apply.
1. The overlay needs 2 fragments, one for the pinmuxing node and
another one for node which would use the pins
2. The overlay must contain a __local_fixups__ section, because this
will let the dtbo loader to link the custom pinmux correctly to your
customized node
3. I am almost sure, that MODE6 is incorrect in your case, however, I
am ready to learn otherwise. I looked up the modes for my project
in the Database of Pins of the bonescript project on GitHup (which
is maintained by one of the BBB developers):
https://github.com/jadonk/bonescript/
P9_13 starts on line 1271 of the bone.js file:
https://github.com/jadonk/bonescript/blob/master/src/bone.js#L1271
P9_11 starts on line 1226 of the bone.js file:
https://github.com/jadonk/bonescript/blob/master/src/bone.js#L1226
AFAIK, the field options contains the array of pinmux modes, starting
at 0. MODE6 is NA in the case of P9_13 and urat4_rxd in the case of
P9_11. You said, you need gpmc_wpn and gpmc_wait0 respectively, and
this would be MODE0 for both pins.
4. In order to find out the input/output flags, I consulted the file:
=
https://svnweb.freebsd.org/base/head/sys/gnu/dts/include/dt-bindings/pinct=
rl/am33xx.h?view=3Dco
Now, I guess, that P9_13 would be simply PIN_OUTPUT, which means flag =
0x00,
and P19_11 would be PIN_INPUT =3D
=3D (INPUT_EN | PULL_DISABLE) =3D
=3D ((1 << 5)| (1 << 3))
=3D 0x28
Said all this, I suggest to try the following overlay - note, I am =
definitely not the authoritative expert:
/dts-v1/;
/plugin/;
/ {
compatible =3D "ti,am335x-bone-black", "ti,am335x-bone", =
"ti,am33xx";
exclusive-use =3D "P9.11","P9.13","uart4";
fragment@0 {
target =3D <&am33xx_pinmux>;
__overlay__ {
gpmc_uart4_pins: pinmux_gpmc_uart4_pins {
pinctrl-single,pins =3D <
0x74 0x00 /* UART4_TXD, =
PIN_OUTPUT | MODE0 */
0x70 0x28 /* UART4_RXD, =
PIN_INPUT | MODE0 */
>;
};
};
};
fragment@1 {
target =3D <&uart4>;
__overlay__ {
status =3D "okay";
pinctrl-names =3D "default";
pinctrl-0 =3D <&gpmc_uart4_pins>;
};
};
__local_fixups__ {
fragment@1 {
__overlay__ {
pinctrl-0 =3D <0x0>;
};
};
};
};
Best regards
Rolf=
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