Dear Samuel,
Many thanks, now it works!
In case anyone is interested, see below in-line for more detailed info
on the DTS and hardware connections:
On 10/28/23 19:32, Samuel Holland wrote:
On 10/10/23 08:57, Ilario Gelmetti wrote:
gpios = <&pio 1 0 0>; /* 1: B of PB0; 0: 0 of PB0; 0:
GPIO_ACTIVE_HIGH */
You need GPIO_PULL_UP in the flags cell here.
Many thanks! I did not have idea that it was possible to set that here!
For people that read this and do not know how to set GPIO_PULL_UP here,
I report what I found about it.
I found some documentation in the first part of this document: [1] and
here: [2].
So I understand that the third parameter of the gpios = <&pio X Y ZZ>
(the first and the second indicate the pin I want to use PB0: X=1 means
"B" and Y=0 means 0) has to be:
bit 0 = 0 for GPIO_ACTIVE_HIGH
and
bit 4 = 1 for GPIO_PULL_UP
so: 0b10000 which in decimal is the number 16.
pinctrl-names = "default";
pinctrl-0 = <&my_w1_pin>;
};
};
};
fragment@1 {
And drop this entire fragment. See if it works with those two changes.
Great, dropped the second part.
Many thanks for your help, now it works!!!
Until today I was completely stuck, and I was going to try compiling
w1-gpio-cl [3] that was also promising.
So, the final DTS file looks like this:
```
/dts-v1/;
/plugin/;
/ {
compatible = "allwinner,sun50i-a64",
"olimex,a64-olinuxino";
description = "Enable 1-Wire port";
fragment@0 {
target-path="/";
__overlay__ {
onewire {
compatible = "w1-gpio";
pinctrl-names = "default";
gpios = <&pio 1 0 16>;
/* 1: B of PB0; 0: 0 of PB0;
16 = (GPIO_ACTIVE_HIGH | GPIO_PULL_UP)
= (0 bitwise OR 16)
0 in the bit 0 means GPIO_ACTIVE_HIGH
1 in the bit 4 = 16 means GPIO_PULL_UP
0b10000 = 16 */
status = "okay";
};
};
};
};
```
It has been compiled with:
```
dtc -I dts -O dtb sun50i-a64-w1-gpio.dts -o sun50i-a64-w1-gpio.dtbo
```
Loaded adding the compiled file path to the spaces-separated list of
fdtoverlays in the /boot/uEnv.txt file and rebooting:
```
fdtoverlays=/root/sun50i-a64-w1-gpio.dtbo
```
Here is the output of some interesting debugging commands, just for
documenting the working status of the system:
```
# dmesg | grep -i wire
[] Driver for 1-wire Dallas network protocol.
[] gpio-32 (onewire): enforced open drain please flag it properly in
DT/ACPI DSDT/board file
[] w1_master_driver w1_bus_master1: Attaching one wire slave
28.00000e21e158 crc 8d
```
Strangely, even if I also set Bit 2 = 1 in the DTS gpios cell, which
corresponds to GPIO_LINE_OPEN_DRAIN [2], the second line in the dmesg
filtered output does not disappear.
```
# cat /sys/kernel/debug/gpio
gpiochip1: GPIOs 0-255, parent: platform/1c20800.pinctrl, 1c20800.pinctrl:
gpio-32 ( |onewire ) out hi
gpio-166 ( |cd ) in lo ACTIVE LOW
gpio-201 ( |usb1-vbus ) out hi
gpio-230 ( |usb0_vbus_det ) in lo IRQ
gpio-233 ( |usb0_id_det ) in hi IRQ
gpiochip0: GPIOs 352-383, parent: platform/1f02c00.pinctrl, 1f02c00.pinctrl:
gpiochip2: GPIOs 510-511, parent: platform/axp20x-gpio, axp20x-gpio, can
sleep:
```
It is surprising to me that it works even if the pin 32 (PB0 on
Allwinner A64) is marked as output :)
```
# cat /sys/kernel/debug/pinctrl/1c20800.pinctrl/pinmux-pins
Pinmux settings per pin
Format: pin (name): mux_owner|gpio_owner (strict) hog?
pin 32 (PB0): GPIO 1c20800.pinctrl:32
pin 33 (PB1): UNCLAIMED
[...]
```
I had to try a few different hardware connections, that were not obvious
to me (noob writing). The final working one can be seen here [4] and is:
* external 5V power supply connected to GND of thermometer and VCC of
thermometer
* A64-olinuxino's 5V pin from GPIO1 port connected to VCC of thermometer
* 10 kOhm (did not try other resistors, 4.7 kOhm should also be ok)
connected from VCC of thermometer and Data of thermometer
* A64-olinuxino's PB0 pin (the one configured using the DTS file)
connected to Data of thermometer
I am not sure these connections are the most meaningful ones (e.g. it
would have been more common to connect the ground of the SBC and of the
external power supplies, instead I had to connect the VCC. I suppose
this happens due to some open-drain configuration?) and it could be they
depend on the DTS configuration, but they are the only one that I found
working.
The position of the PB0 and 5V pins in the GPIO1 port of the
A64-olinuxino rev. G is reported here [5].
As I am using some Maxim DS18B20 thermometers [6], I added w1_therm in
the /etc/modules file to have it loaded at boot.
Without that module loaded, the important file
/sys/bus/w1/devices/28-00000???????/w1_slave
does not appear.
[] Driver for 1-wire Dallas network protocol.
[] sun50i-a64-pinctrl 1c20800.pinctrl: pin PB0 already requested by
onewire_device; cannot claim for 1c20800.pinctrl:32
[] sun50i-a64-pinctrl 1c20800.pinctrl: pin-32 (1c20800.pinctrl:32)
status -22
[] w1-gpio onewire_device: gpio_request (pin) failed
[] w1-gpio: probe of onewire_device failed with error -22
The problem is that the GPIO reference and the pinctrl reference for the
same pin conflict. In this case, the only thing you need the pinctrl
reference for is the pull-up, which you can achieve with a GPIO flag.
However, for the more general case, you may need to apply some other
pinconf setting to a GPIO pin, so we may need to fix this.
For me, it is surprising how other people do not have my same issue.
For example, in the instructions on the wiki [7], in the DTS from
Armbian [8] and in the one used by RaspberryPi (on Broadcom) [9] they
all use the same pin in two fragments. I tried using all of these and
always got the "already requested by" error.
Regards,
Samuel
Many thanks!!!
Ilario
[1]:
https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt
[2]:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/dt-bindings/gpio/gpio.h
[3]: https://github.com/pstolarz/w1-gpio-cl
[4]: https://uz.sns.it/~ilario/20231030-1wire-A64-hardware_connections.jpg
https://web.archive.org/web/20231030154013/https://uz.sns.it/~ilario/20231030-1wire-A64-hardware_connections.jpg
[5]:
https://github.com/OLIMEX/OLINUXINO/blob/master/HARDWARE/A64-OLinuXino/1.%20Latest%20hardware%20revision/A64-OLinuXino%20hardware%20revision%20G/A64-OlinuXino_Rev_G.pdf
[6]:
https://www.olimex.com/Products/Components/Sensors/Temperature/SNS-TMP-DS18B20/
[7]: https://linux-sunxi.org/1-Wire#Device_Tree
[8]:
https://github.com/armbian/sunxi-DT-overlays/blob/master/sun50i-a64/sun50i-a64-w1-gpio.dts
[9]:
https://github.com/raspberrypi/linux/blob/rpi-6.1.y/arch/arm/boot/dts/overlays/w1-gpio-overlay.dts
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