dts example for the Linux kernel for Microblaze

[loberman]

Firstly I am NOT using Petalinux, I am building my own kernels,

I have the pmod OLED working via a standalone application and now I am working on getting it accessible under Linux.

The Vivado device tree generator does not create a spi entry for the OLED in the dts files.

Can I get an example of what I need to add to the kernel dts file so I can access the pmod OLED from Linux via SPI.

 

Thanks

Laurence

 

[jpeyron]

Hi @loberman,

I have reached out to more experienced embedded linux engineers to see if they have any input for you.

thank you,

Jon

[loberman]

Hello Jon

Thank you,

I am also working on a dts entry and will let you know if I get there first.

[morsucci]

@loberman

thank you for your question.

I have used the PMOD OLED with a petalinux project and have attached the device tree for it here.

Keep in mind you'll need to change the address in the entry to your relevant hardware address.

		SPI_OLED: axi_quad_spi@41e10000 {
			bits-per-word = <8>;
			compatible = "xlnx,xps-spi-2.00.a";
			fifo-size = <16>;
			interrupt-parent = <&intc>;
			interrupts = <0 31 1>;
			num-cs = <0x1>;
			reg = <0x41e10000 0x10000>;
			xlnx,num-ss-bits = <0x1>;
			xlnx,spi-mode = <0>;
		};

Keep in mind, if you want to control the VBATC, D/C, VDDC, and RES pins, you'll need a GPIO entry as well, like this one:

		axi_gpio_0: gpio@41200000 {
			#gpio-cells = <2>;
			compatible = "xlnx,xps-gpio-1.00.a";
			gpio-controller ;
			reg = <0x41200000 0x10000>;
			xlnx,all-inputs = <0x0>;
			xlnx,all-inputs-2 = <0x0>;
			xlnx,all-outputs = <0x0>;
			xlnx,all-outputs-2 = <0x0>;
			xlnx,dout-default = <0x00000000>;
			xlnx,dout-default-2 = <0x00000000>;
			xlnx,gpio-width = <0x8>;
			xlnx,gpio2-width = <0x20>;
			xlnx,interrupt-present = <0x0>;
			xlnx,is-dual = <0x1>;
			xlnx,tri-default = <0xFFFFFFFF>;
			xlnx,tri-default-2 = <0xFFFFFFFF>;
		};

If you are using the PMOD OLED IP core provided by digilent, you'll have a GPIO controller and SPI controller wrapped up in that core, so it is a matter of finding the correct addresses for each core and changing the GPIO width to 4 to match the 4 gpio pins on the PMOD OLED.

 

Let me know if you have any questions.

 

Mitchell

[loberman]

Awesome and Thanks, trying it and will reply back

[loberman]

Still working on this, trying to get the spidev driver to work and will post when done.