device-tree

问题 I am trying to setup a driver for an embedded PowerPC board, and the correct way to do this today is to use the OpenFirmware Device Tree datastructure (the .dtb file, compiled from a .dts file). Creating a tree is pretty easy, but how do I get my device driver to find its node and the data in it? I have not managed to find any good reference on this, and books like "Linux Device Drivers" are too much into x86 land to be of much help for device trees that mostly pertain to Power Architecture

问题 I am trying to write a common clock framework driver for a clock that I have attached to my Raspberry PI 3 via I2C. NOTE: I am very new to both Linux and kernel programming. Update: SUCCESS! The code below works for a Hello World driver, and the sole change I had to make to the device tree to get my driver to load was to add a child of the i2c1 node (in arch/arm/boot/dts/bcm2708_common.dts): i2c1: i2c@7e804000 { compatible = "brcm,bcm2708-i2c"; reg = <0x7e804000 0x1000>; interrupts = <2 21>;

问题 If I build a kernel driver as a module , it can be inserted into the kernel at run-time manually with insmod or modprobe, that i am clear. But are the following statements about device tree, correct? If I build a kernel driver as a module it will be auto inserted into the kernel at boot time, depending on whether it is listed in device tree or not If I build a kernel driver as a built-in , it will be auto inserted into kernel at boot time regardless of device tree 回答1: Built-in kernel driver

问题 As per my understanding chosen node is used to send boot arguments to the kernel. The following is the chosen node of the existing device code (am335x-bone-common.dtsi). chosen { stdout-path = &uart0; }; So, I have modified chosen node to pass kernel arguments. chosen { bootargs = "console=ttyO0,115200 root=/dev/mmcblk0p2 rootfstype=ext3 rw rootwait"; stdout-path = &uart0; }; While bringing up the board I encountered KERNEL PANIC, Here is the log {https://pastebin.com/XHyrsmfG} FYI: These are

问题 I'd like to boot the raspberry pi with a device-tree-driven linux kernel, is there anything special to do to do that? Can anyone point what are required to set up a device-tree-based kernel boot up for the raspberry pi. I may need to have raspberry pi kernel source where drivers for devices should be compatible with device tree. If so, where can I find such kernel sources for Raspberry Pi? 回答1: Device-Tree support on Raspberry Pi Raspberry Pi embeds an ARM11 SoC: Broadcom BCM2835. Device Tree

问题 I'm using Embedded Linux on a board that is mainly configured via the device tree mechanism ( .dts / .dtc files), i.e. entries in the device tree file indicate which devices to register and thereby which drivers to load. Is there a way to manually load a dynamic module in a way that resembles what would happen when this driver would be loaded by the device tree handler? To clarify: instead of having an entry for device XXX in my .dts file, can I "manually" register this device (for example by

问题 I have SAMA5D27-SOM1-EK1 Board. It has 3 Leds ( Red connected to PA10 pin , green connected to PB1 pin , blue connected to PA31 pin ) and 4 buttons, one of them is user push button (PB4) connected to PIO PA29, and optionally to PIOBU1. This is a link to device-tree file for my linux kernel : https://github.com/torvalds/linux/blob/master/arch/arm/boot/dts/at91-sama5d27_som1_ek.dts You can find a part which describing LED and User Push Button : leds { compatible = "gpio-leds"; pinctrl-names =

问题 I'm going to launch a Linux on my development board, and i need a dts file (device tree file) to describe the whole hardware. But I only know very little about the syntax of this file which is not enough to run Linux properly on the board. What i know now are only how to describe a unit's interrupt number, frequency, address, parent-unit and its compatible driver type (as described below): ps7_scuwdt_0: ps7-scuwdt@f8f00620 { compatible = "xlnx,ps7-scuwdt-1.00.a"; device_type = "watchdog";

问题 I am using SAMA5D27-SOM-EK1 embedded board. I build for it Linux image OS using YOCTO project version SUMO. I need to know device's GPIOS ( gpios-leds and gpios keys specialy) and the mapping of the board. When I enter in /sys/firmware/devicetree/base/leds/red for example in the board terminal I can find gpio file but when i open it there are symbols which i can't read. I think that I can find such things in the generated Device Tree but i can't find its path! Please help me out 回答1: Here is

问题 I been trying to read child node property in a device tree.. Could not figured it out, can any one help here. I have a dts AA{ child 1: { property 1 : XXX property 2 : XXX } child 2 :{ property 1 : XXX property 2 : XXX } BB{ child 1: { property 1 : XXX property 2 : XXX } child 2 :{ property 1 : XXX property 2 : XXX } Is there any way of reading properies of child 2 in AA node of given dts ? 回答1: Yes, you can do it. Just write a similar function as below and call it in AA with the path of the