Hi I am trying to create a dvb frotnend for my device on ubuntu. I have created a device driver file that creates a dummy dvb file after looking at dummy_dvb_fe.c which is present in the linux kernel. For some reason when I insmod it I am not able to see anything in my /dev folder. Generally a device node under /dev/dvb/adapter should get created. I am not sure if any other files need to be changed for front end registeration. due to the lack of documentation I am not sure about the process of creating a dvb frontend device driver and registering it.
Well I figured it out. Issue was I was looking into the Linux TV user space DVB-API documentation instead of the Media Kernel API documentation. In any case
You have to create, populate and register a dvb_adapter after which you have to create and register a dvb_dummy device.
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I created an small embedded WinUSB device which offers 2 bulk endpoints. This device can communicate with Linux and with Windows10 without installing driver, or a .inf file.
Now we want to use the same API with a embedded Linux. The USB-Gadget mode offers Serial CDC/ACM and RNDIS-Ethernet and many more.
I was able to create a USB-Gadget with the gadgetfs which had only bulk ep. I could communicate with Linux and Windows host. The USB-Device had /dev/ttyGS0 to communicate. But in Windows I had to install WinUSB driver manually.
I work with yocto to create embedded kernel.
I added some line of code here: /linux-imx/drivers/usb/gadget/legacy/serial.c , f_serial.c, u_serial.h to add additional variable os_desc and parameter use_winusb. But the resulting g_serial still creates a COM-Port in Windows10 or a no WinUSB device. For our device we need WinUSB-Device only.
The RNDIS Gadget does has WinUSB support. So I tried to create a own USB-Gadget device with https://github.com/libusbgx/libusbgx. But if I use the USBG_F_SERIAL function type then it can't create WinUSB. See error:
Error setting function OS desc
Error: USBG_ERROR_NOT_FOUND : Not found (file or directory removed)
If I use USBG_F_RNDIS, it works, and with manipulated USB descriptor it'll recognized by Windows as WinUSB device. But Linux implement's it as USB-ETH ethernet device. The USB-Device get's no /dev/ttyGS0 serial connection to communicate.
I'm reading the Linux kernel driver source now, to find the position, where I can simply ann this WinUSB os-descriptor stuff into the USBG_F_SERIAL type. But I think it'll take month to get through.
Any solution would be ok. Patch for the Linux driver sources g_serial or how to configure a USB-Gadgetfs would be great. Any hint, where to put additional code would also be fine.
I wanted to change the kernel, but fortunately found this:
https://blog.soutade.fr/post/2016/07/create-your-own-usb-gadget-with-gadgetfs.html
This code made it easy to add WinUSB features.
Source of modified Version for WinUSB: https://github.com/rundekugel/gadgetfsd/tree/WinUSB
I'm working on a Cyclone V SOC FPGA from Altera with a double Cortex-A9 processor. The embedded system (linux 4.15.7) is created with Buildroot-2018.02. U-boot is used to load the system i-e FPGA.rbf file, device tree blob and zImage and everything works fine.
I want now to integrate the RBF file to my linux and program the FPGA from Linux. I found several methods and the one I understand is the most common is to use CONFIGFS with a device-tree overlay.
So I changed my device tree to integrate the overlay, the u-boot boot script to disable FPGA load and also the following options in the linux ".config" file with make linux-xconfig :
+CONFIG_OF_OVERLAY=y
+CONFIG_ALTERA_STAPL=y
+CONFIG_CONFIGFS_FS=y
+CONFIG_SAMPLES=y
+CONFIG_SAMPLE_CONFIGFS=m
These options are the state were I am now after several try.
After a make and a reboot, once the kernel is loaded, I enter the following command in the console :
mkdir /config
mount -t configfs none /config
At this state, I'm expecting to see some device tree files in the /config folder but there wasn't any, only one rdma_cm folder :
# ls /config
rdma_cm
I continued my reading on this topic and found that I must enable the CONFIG_OF_CONFIGFS option in my linux kernel.
PROBLEM: This option is not available in my linux kernel. Also, file drivers/of/configfs.c is no here too. I've searched in vain to find how to enable device tree overlay for my kernel version.
How can I configure my kernel to make device-tree available in configfs ?
I had the same problem as you. So I had to make a device driver by myself.
This device driver is tentative and I expect Linux mainline to officially support Device Tree Overlay ConfigFS.
The device driver I made is available at the following URL.
https://github.com/ikwzm/dtbocfg
If you are using Debian, you can build the Debian Package of the device driver with the following URL.
https://github.com/ikwzm/dtbocfg-kmod-dpkg
If you want to try Device Tree Overlay using this device driver, please refer to the following URL.
https://github.com/ikwzm/FPGA-SoC-Linux
https://github.com/ikwzm/FPGA-SoC-Linux-Example-1-DE10-Nano
I have an embedded system running Linux, with many peripheral devices connected.
There are some storage devices connected too. Currently, we do not have any diagnostics tool to check the state of devices on the system.
what I want to do with this diagnostics tool is something like:
After connecting to my embedded system either via USB or network port, I want to be able to browse storage media ( in read only mod ), and may be later in future extend this to check the status of other devices running.
With this question, I am seeking guidance of expert people who have faced similar problem and were successfully implement a solution.
I am not looking for a solution but a likely approach.
thanks
one approach is that (it totally depends on your embedded board)
if your board supports booting from the usb, you can modify your bootloader code to boot linux initrd image from the usb, if usb is plugged in your board, otherwise noraml booting procedure.
you can write one c diagnostic utility to check the status of different peripherals and generate the report on the usbdisk
create Linux initrd image for your board with modified rcS file to mount the usb in Linux and start the utility while boot up, copy the utility in bin folder of your rootfilesystem.
now when you power-on your board with usb connected, your testing software will boot and test the peripherals otherwise your normal software will boot.
hope this helps!!
I'm having a bit of a hard time fully understanding how the kernel starts in linux. I'm a wince developer and our company decided to run with linux instead now.
We outsourced all of the board bringup and the package I recieved is quit a bit different for the prototype board we have compared to the nitrogen6x we have been using.
Before i start listing the differences for the distro we created, the kernels are identical. The distro we have been using is a busybox system. The one we recieved from the vendor is sysvinit. I removed mdev from busybox and we are only using udev.
when I use the kernel on our busybox build the touch screen drivers breaks, or doesn' run, or does something totally magical. I'm not quit sure... there is a /dev/input/event0 device which when run on the sysvinit side is a touch device.. Is the kernel not the mechanism that binds the built-in drivers to a device node? I thought udev was for more dynamic events in the system.
On the other hand I can't really tell whats been loaded on my device. Is there a way to list running drivers that were built into the kernel? my touch pad is up? This is a fairly simple process of looking at the registry on wince to see which devices were loaded.
I guess what I'm really trying to discover, isn't so much how to add a driver to the kernel, its how the whole thing gets is plumbed together. I've found plenty of documents on createing kernel modules, but i haven't found a good resource on how to pull everything together from scratch so you can actually use said modules. Going back to the example of the touchscreen driver, its built into the kernel, how does that get plugged into /dev/input/event0??
I'm kind of having a difficult time finding good resources mostly because searching google for varations of linux/drivers/device nodes/ piles in tons of random crap from everywhere.
What you probably want to use now is evtest. It will allow you to know what are the input devices that are present and ready to use on your system.
To get more information on the input subsystem and more generic information on how the kernel is working, I can direct you to our training materials. The materials are free to download, use and redistribute.
The general answer is, there is no single, easy place to look to discover what drivers have been loaded by the kernel if they are compiled in. Of course, lsmod will display any drivers that were dynamically loaded after kernel boot.
The kernel does not create device nodes. That is, to quote your question, the kernel does not "bind" the driver to the device node. The association between kernel driver and device node is contained in the major and minor numbers registered when the driver is initialized. You can have a device node on your file system for which there is no corresponding driver (common especially in older devices where device nodes were statically created on the file system) and you can also have a driver installed for which there is no device node.
Modern Linux distros have dynamically created device nodes created on a mount point called /dev and this is usually a tmpfs file system, meaning it is volatile - it gets destroyed on every boot and recreated dynamically on each new boot.
udev is the magic that creates most device nodes based on events that it receives from the kernel when a new device is discovered (this can be after boot on device plugin, like a USB disk) or on startup when udev reads the queued events and acts on them. As you noted, busybox has a limited udev implementation called mdev.
Study udev and you will get a much better understanding of the process. Hope this helps a little.
Dokan currently does not create a virtual hard disk for its filesystem (i.e. in Device manager, you dont see another disk drive). Anyone have any idea on how to start to correct that?
Dokany is the active fork of Dokan and bring the ability to create virtual drive.
Dokany have made big progress by implementing the mount manager of dokan. There is only the PnP part that is not totally implemented. When this will be added, you will see the dokan device in the device manager.
Representation in device manager requires a plug-n-play device driver. so you need to write one. Or use our Callback File System