Linux Port of SSD1306 Oled Controller Driver

Introduction

This is a Linux port of the SSD1306 driver originally implemented for the ESP-IDF framework by wolffshots here. The SSD1306 is a monochrome OLED display controller. This implementation is based on the linux i2c subsystem

Features Implemented

(Still in progress)

• Basic initialization and configuration.
• Device file Operations
  • Open
  • Read
  • Write
  • ioctl
• Drawing primitives: lines, rectangles, circles.
• Text rendering.
• Screen rotation support.
• I2C communication protocol support.
• SPI communication protocol support.
• User space sample applications
  • Open
  • Write
  • Read
  • ioctl

Environment

Toolchain

The toolchain was built with crosstool-NG using the armv8-rpi3-linux-gnueabihf sample config

Linux Kernel

The Linux Kernel I used is Raspberry Pi Foundations fork of the mainline kernel found here

Development Board

Tested on Raspberrypi 3A+ and 3B+ models (with BCM2837B0 SOC)

Usage

To use this driver, follow these steps:

1. Setup a build environment (get or build a toolchain)
2. Build the kernel (mainline Linux kernel or Raspberry Pi's fork) and boot your board
3. Clone the repository.
4. Copy the device tree to the arch/arm(64)/boot/dt
5. Compile the driver and device trees with Kbuild and transfer the built module and device tree binary to the target.
6. Use the userspace application to interact with the device in /dev/ssd1306X

Notes

The Porting Process

The architecture independent part of the orginal driver ssd1306.c is largely untouched. The corresponding original sources files were renamed to linux_xxxx. Mostly the function prototypes were modified to return values to the caller as it typical with linux driver functions and logging functions changed appropirately.

Device Tree to Use

The bcm28xx* device tree are the upsteam Linux support files for the bcm SOC family while the bcm27xx* are downstream code by Rasberry Pi Foundations. See here

Modifying the Device Tree to Include the ssd1306 controller

Here is a sample device tree modification for using the i2c1 controller. (also see the modfied .dts file on this repo. )

&i2c1 {
	pinctrl-names = "default";
	pinctrl-0 = <&i2c1_pins>;
	clock-frequency = <100000>;

    //start
	status = "okay";
	ssd1306@3c{
		compactible = "solomon,ssd1306";
		reg = <0x3c>;
	};
    //end
};

License

This software is released under the MIT License. See the LICENSE file for more information.