sysfs

问题 In Linux, is there a way to find out which PCI card is plugged into which PCI slot? /sys/bus/pci/devices/ contains many devices (bridges, CPU channels, etc.) that are not cards and I was not able to find any information about slot-card mappings in the device directories. 回答1: You can use dmidecode –t slot to find all available pci slots than you can run lspci -s <slot number> command to list device connected to specified slot. You must take bus address from first command and use this address

问题 In Linux, is there a way to find out which PCI card is plugged into which PCI slot? /sys/bus/pci/devices/ contains many devices (bridges, CPU channels, etc.) that are not cards and I was not able to find any information about slot-card mappings in the device directories. 回答1: You can use dmidecode –t slot to find all available pci slots than you can run lspci -s <slot number> command to list device connected to specified slot. You must take bus address from first command and use this address

问题 I need to use a system without any sysfs/debugfs (this is a strong requirement, can't change it). I need to understand how I can manage to set the Linux without this filesystem. For example when configuring various omap PM (power management features) I need to set the following: echo 1 > /dbg/pm_debug/sleep_while_idle Do you think it is possible to set it as default to 1 for example (I don't need to change the value in runtime) ? How can it be done ? 回答1: I find that the values that are set

问题 My aim is to control the GPIO pins in Peppermint 4 Linux (Kernel version 3.8.0) on an Intel motherboard (NM70 chipset with C1037U processor). How can you check whether your kernel supports GPIO on your hardware? Background Motherboard: Intel with NM70 chipset Processor: C1037U processor OS: Peppermint 4 Linux Kernel version: 3.8.0 GPIO interface: sysfs I'm attempting to use the sysfs interface, which allows GPIO pins to be accessed from userspace through the filesystem. I’ve successfully

问题 as the title states, I have a problem porting some userspace-interrupt code from another armv7 embedded linux platform onto the Raspberry Pi 2 Model B. I'm aware of the wiringPi library (and got it to work that way), but for evaluation reasons I want to do run as much identical code as possible on both platforms. For that reason I have to interface with sysfs by hand. So, here's the relevant code snippet #define GPIO_TRIGGER_MODE "rising" #define SYS_GPIO_PIN "2" #define SYS_GPIO_DIRECTION "

问题 I have some question about Linux kernel and GPIOs. I know that in Linux everything is file so when I do something like echo 30 > /sys/class/gpio/export and echo 1 > /sys/class/gpio/gpio30/value what really happens? I mean how does sysfs handle that? Does it call system calls implemented in gpiolib? 回答1: The gpiolib registers the value attribute in this way: static const DEVICE_ATTR(value, 0644, gpio_value_show, gpio_value_store); It creates a device attribute named value , with permission 644

问题 I'm trying to access the GPIO pins of a Raspberry Pi 2 using the robot operating systen ROS. I know, there are many tutorials on this topic. But my problem is as follows: The recommended Linux distribution for ROS is Ubuntu . Since there are other Ubuntu machines in the ROS network, I'd like to avoid compiling ROS for a different OS. In Ubuntu the /sys/class/gpio sysfs is not enabled by default. I'd need to recompile the kernel with a custom configuration. If I can't use /sys/class/gpio , it

问题 I am doing some experiments on SAMA5D27-SOM1-EK1 board. I am using Linux operating system. I am exploiting GPIOS of my board. There is RED LED defined at GPIO 10 and USER button defined at GPIO 29 . I wrote C++ program to control LED of the board and here is the code : #include<iostream> #include<fstream> #include<string> using namespace std; #define LED0_PATH "/sys/class/leds/red" void removeTrigger(){ // remove the trigger from the LED std::fstream fs; fs.open( LED0_PATH "/trigger", std:

问题 Assume that the gpio X can be exported in sysfs as an input pin, after doing that a directory called gpioX will be created into /sys/class/gpio/. gpioX/ contains few file such as "value" which represents the current state of the gpio X (high or low). What happens (in kernel space) when the signal applied to the pin X changes its state (for example from low to high)? I mean, before the transition gpioX/value contains "low", but after that it will contain "high" value. How is this file updated

问题 I would like to use interrupts with GPIO on userspace using sysfs. I use these commands : [root@at91]:gpio109 > echo 109 > export [root@at91]:gpio109 > cd gpio109/ [root@at91]:gpio109 > ll -rw-r--r-- 1 root 0 4096 Jan 1 00:17 direction drwxr-xr-x 2 root 0 0 Jan 1 00:17 power lrwxrwxrwx 1 root 0 0 Jan 1 00:17 subsystem -> ../../gpio -rw-r--r-- 1 root 0 4096 Jan 1 00:17 uevent -rw-r--r-- 1 root 0 4096 Jan 1 00:17 value The gpio works well but I can't use interrupts. I read everywhere i must