avafinger
commented
6 years ago @noradtux
To enable uart3 you can do the following:
-
do a backup of the DTB file you will change in case something goes wrong
-
find the DTB file in use
cd /boot ll bpi-m2-zero.dtb
you will see the linked file as something like this (the extension will be your current kernel version):
lrwxrwxrwx 1 root root 29 Jul 22 12:36 bpi-m2-zero.dtb -> bpi-m2-zero-v1.dtb_4.17.9-m2z
-
Decompile the dtb file to a source file which you can edit
sudo dtc -I dtb -O dts -o m2z.dts bpi-m2-zero-v1.dtb_4.17.9-m2z -
edit the DTS (source file is the m2z.dts) and enable the uart3 like so:
serial@1c28000 {
compatible = "snps,dw-apb-uart";
reg = <0x1c28000 0x400>;
interrupts = <0x0 0x0 0x4>;
reg-shift = <0x2>;
reg-io-width = <0x4>;
clocks = <0x3 0x3e>;
resets = <0x3 0x31>;
dmas = <0x14 0x6 0x14 0x6>;
dma-names = "rx", "tx";
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <0x1c>;
};
serial@1c28400 {
compatible = "snps,dw-apb-uart";
reg = <0x1c28400 0x400>;
interrupts = <0x0 0x1 0x4>;
reg-shift = <0x2>;
reg-io-width = <0x4>;
clocks = <0x3 0x3f>;
resets = <0x3 0x32>;
dmas = <0x14 0x7 0x14 0x7>;
dma-names = "rx", "tx";
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <0x1d 0x1e>;
};
serial@1c28800 {
compatible = "snps,dw-apb-uart";
reg = <0x1c28800 0x400>;
interrupts = <0x0 0x2 0x4>;
reg-shift = <0x2>;
reg-io-width = <0x4>;
clocks = <0x3 0x40>;
resets = <0x3 0x33>;
dmas = <0x14 0x8 0x14 0x8>;
dma-names = "rx", "tx";
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <0x1f>;
};
serial@1c28c00 {
compatible = "snps,dw-apb-uart";
reg = <0x1c28c00 0x400>;
interrupts = <0x0 0x3 0x4>;
reg-shift = <0x2>;
reg-io-width = <0x4>;
clocks = <0x3 0x41>;
resets = <0x3 0x34>;
dmas = <0x14 0x9 0x14 0x9>;
dma-names = "rx", "tx";
status = "disabled"; <<== change this to: status = "okay";
pinctrl-names = "default";
pinctrl-0 = <0x20>;
};
Save the file and then recompile it to the original file name, like so:
Ps: edited
sudo dtc -I dts -O dtb -o bpi-m2-zero-v1.dtb_4.17.9-m2z m2z.dts
- Now you can sync && sudo shutdown -h now , and power cicle the board
You should have now uart3 enabled on next boot.
patrickpoirier51
meisterbasti
Hi, I currently use an uart on the GPIO port with the original kernel (ttyS3). Is it possible to get this working on this kernel?