I am writing a USB device drive for linux. it's for a joystick.
every time plug it in, linux loads a hid driver. is there a way to tell Linux to load mine when I plug it in? or at least not load the default one?
I can echo the id in unbind of the default driver and echo it in bind of my driver; but I would like something more automatic..
thanks
Own USB driver taking precedence over usbhid
If you want to prevent binding to the usbhid driver, you can use its HID_QUIRK_IGNORE (= 4) setting. To stick with the example Karl Bielefeldt used, add
options usbhid quirks=0x15c2:0x0043:0x04
to some /etc/modprobe.d/*.conf file (and perhaps recreate your initramfs). That will tell hid-core to ignore that device. So usbhid will have a look at it but leave it for some other driver instead.
Own HID driver taking precedence over hid-generic
However, if your other driver is a HID driver not an USB driver, then you need usbhid to bind to the driver on the USB level, and you need your own HID driver to take precedence over hid-generic. This is the problem I'm facing my self, and for which I haven't found a solution yet, short of unbinding and rebinding the device later on.
Here's a thread with a fix for a similar problem. To summarize, you add something like the following to one of your /etc/udev/rules.d files:
SYSFS{idVendor}=="15c2", SYSFS{idProduct}=="0043", MODE="0666", PROGRAM="/bin/sh -c 'echo -n $id:1.0 >/sys/bus/usb/drivers/usbhid/unbind;\
echo -n $id:1.1 >/sys/bus/usb/drivers/usbhid/unbind'"
http://lwn.net/Articles/143397/ is very similar to the above answer, maybe some more details.
Related
I am facing a problem when i try to read from usb device at u-boot.
When i do
fatls usb 0:1
it says bad device. But as soon as i do
usb start
fatls usb 0:1
then it shows me correcly the fat partition in USB.
I was looking to add both commands in the common/main.c so that whenever the board boots it looks for the fat partition of USB.
It is tough but i need to do it.
Anybody has a clue??
As has been said in the comments, "usb start" is what initializes the USB subsystem and scans attached devices for things U-Boot can deal with (USB sticks, ethernet, etc). Unlike some buses such as MMC that we will do an initial scan on prior to starting the shell, for USB you must run the start command first if you expect to use devices that are attached.
Now, you don't add things to common/main.c, you add things to the bootcmd environment variable (and this can be changed in the boards config.h file so that the default environment is changed, if you are working on a board where you cannot do 'saveenv' to save your changes in a persistent way). So what you would want to do is:
=> setenv bootcmd 'usb start;fatls usb 0:1'
or whatever commands you wish to do with the files present on the USB stick.
When does the console and UART binding happen in Linux,is it possible to unbind the UART from console and bind it to other module(GPS) at runtime.
My board is having a single UART,can i switch between console and GPS at runtime.if yes how do i do it? if no what is the hack which I need to do?
Yes you can. At run time you can unbind/bind any driver. You can find more information here:
https://lwn.net/Articles/143397/
You can find the correct driver for your the UART (and GPS probably, but I'm not sure. Never played with it) here:
cd /sys/class/tty/<your-device>/device/driver/
Then in these directories you have the sysfs files bind and unbind. The device ID to use to unbind the device from the driver is typically show in the driver directory.
The platform_device is not special at all, it behaves like any other driver. Typically the device id of a platform device it's its name (there is not a bus enumeration behind). Here an example with platform_device with my PC:
# ls /sys/bus/platform/devices/
alarmtimer gpio_ich iTCO_wdt platform-framebuffer.0 PNP0800:00 PNP0C14:00
coretemp.0 hp-wmi microcode PNP0003:00 PNP0C04:00 serial8250
Fixed MDIO bus.0 i8042 pcspkr PNP0103:00 PNP0C0C:00
# cd /sys/bus/platform/drivers/serial8250/
# ls
bind serial8250 uevent unbind
I am trying to understand how to address devices behind I2C Mux like PCA9548 in linux.
If the topology is something like
CPU->I2C_A Controller->PCA9548->Channel 0->RTC
CPU->I2C_A Controller->PCA9548->Channel 1->Temp Sensor
CPU->I2C_B Controller->PCA9548->Channel 0->Voltage Sensor
CPU->I2C_B Controller->PCA9548->Channel 1->Speed Sensor
I want to know the representation of these devices in user space? What are the associated sysfs entries?
I also want to know if pc9548 is the only driver required in kernel and i2c-dev and i2c-core are already available? Or driver for RTC/sensors is also required?
I have tried to read this, but could not follow it much.
My requirement is to read/write to those devices from user space. Do I have to instantiate devices and assign addresses to it in startup script?
Thanks,
Hemant
You could use i2c-tools for manipulation at user space, if the driver has some problem.
Also you'll need enable the kernel module "i2c-dev" for the char device.
Like /dev/i2c-0
link here.
The necessary driver are i2c-mux, pca954x, I believe you already have i2c-core.
Also you should describe all the I2C devices in device tree or other files.
If the driver is prepared, you may see 8 i2c adapters under /dev, and their salve device is under /sys/bus/i2c.
I read from LDD3 chapter 14 about hotplug drivers.I need to write a usb mouse driver which load when I plug the hardware. Now, doing some experiment I come to know that there is a driver named "hid-generic" which is called when plug-unplug.
[ 6654.232046] usb 3-1: new low-speed USB device number 3 using uhci_hcd
[ 6654.462061] usb 3-1: New USB device found, idVendor=093a, idProduct=2510
[ 6654.462067] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 6654.462071] usb 3-1: Product: USB OPTICAL MOUSE
[ 6654.462074] usb 3-1: Manufacturer: PIXART
[ 6654.489316] input: PIXART USB OPTICAL MOUSE as /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/input/input12
[ 6654.489445] hid-generic 0003:093A:2510.0004: input,hidraw0: USB HID v1.10 Mouse [PIXART USB OPTICAL MOUSE] on usb-0000:00:1d.1-1/input0
Also lsmod shows,
Module Size Used by
hid_generic 12541 0
usbhid 47259 0
hid 105241 2 hid_generic,usbhid
psmouse 102541 0
My doubts are as follows,
1) To make my module load (hotplug) when this mouse plugs in, I have to disable these 3 drivers in kernel and build whole kernel with my driver with vendor and device ID in id_table. Right?
2) I also read about USB core drivers and USB device drivers. So these HID drivers are core drivers or device drivers?
3) Which are core drivers and device driver in case of USB mouse? And where can I find them in kernel source?
Thanks,
Sunil.
I'll try to answer your questions one by one :
1) To make my module load (hotplug) when this mouse plugs in, I have to disable these 3 drivers in kernel and build whole kernel with my driver with vendor and device ID in id_table. Right?
Yes, but there are some additional things you need to take care of. First understand how a particular module(driver) gets loaded. The key to this is MODULE_DEVICE_TABLE(usb, &my_id_table); Whenever a particular module is "installed" (using make modules_install), an entry, according to the id table passed in MODULE_DEVICE_TABLE gets created in /lib/modules/<your_kernel>/modules.usbmap and /lib/modules/<your_kernel>/modules.dep file(search for the string "usbhid" in the files). Whenever a new usb device is detected, the kernel reads these files to find the matching parameters. If it is found, the following module is loaded from the corresponding path found in /lib/modules/<your_kernel>/modules.dep which holds the info. about the path where the driver is located and also its dependencies.
So, now even if you unload(rmmod) usbhid from the kernel, it will be loaded again when you re-insert your mouse. To avoid this from happening you need to modify those files, i.e. remove the entries from the files. To do so, "move" the usbhid driver from its original path(generally located at /lib/modules/<your_kernel>/kernel/drivers/hid/usbhid/usbhid.ko to a safe place. Now rebuild the dependencies such that the entries would be removed from the dependency files.
Now you need to create entries of your driver. Just install your driver and you are good to go!
So, to summarize :
$ sudo rmmod usbhid # Unload the usb mouse driver
$ cd /lib/modules/$(uname -r)/ # Move to your current kernel
$ vim modules.usbmap # Check for the "usbhid" string
$ vim modules.dep # Check for "usbhid.ko:" string
$ sudo mv kernel/drivers/hid/usbhid/usbhid.ko ~/Desktop # Take backup of your current
usb mouse driver
$ sudo depmod -a # Rebuild the dependency files
Now check the dependency files for the string "usbhid" again. It shouldn't be there!
$ cd /path/to/your/driver
$ sudo make modules_install # Install your driver into /lib/modules/$(uname -r)/extra
$ sudo depmod -a # Rebuild the dependency files
After this step, search for the string corresponding to your module in the dependency files, and it should be there! From this moment on, whenever you insert the mouse(or from boot itself) your driver will be loaded, instead of the original.
Once your are done playing with your driver, you may copy back the original usbhid file to its original destination and rebuild the dependency files (sudo depmod -a)
Now I also see that you are trying to use vendor and device id to match your device, in which case, the driver would work only for your mouse. The recommended way is to use class ids, which makes your driver work for any usb mouse.
2) I also read about USB core drivers and USB device drivers. So these HID drivers are core drivers or device drivers?
usbhid is basically a "device driver". The classification of drivers could be briefed out as : core drivers, host controller drivers and device drivers :
Device Drivers : This is the software used to control the devices. For example usb mouse, pci based ethernet card, usb pendrive, i2c based accelerometer.
Host Controller Drivers : This is the software written to control the bus controller. For example USB Host Controllers(EHCI, UHCI, OHCI, etc.), PCI Host Controller, I2C Masters, etc.
Core Drivers : These actually glues up the above discussed drivers. Examples are USB core, PCI core, etc. Core drivers provides helper routines(APIs) such that the device and host-controller driver could make use of them(concept of module stacking!). These are the ones, which bind the correct device to its driver. There are many other services provided by the core drivers.
Example code for USB Device Driver :
http://lxr.free-electrons.com/source/drivers/hid/usbhid/usbmouse.c
You may find the USB Host Controller Drivers under :
http://lxr.free-electrons.com/source/drivers/usb/host/
USB Core resides here : http://lxr.free-electrons.com/source/drivers/usb/core/
I think this also answers your third question!
Hope this helped.
The device driver is usbhid.
To prevent it from attaching to your device, add a HID_QUIRK_IGNORE entry to drivers/hid/usbhid/hid-quirks.c, or use the quirks parameter of the usbhid module.
Is it possible to turn on/off power supplies from USB manually with Linux?
There's this external USB cooling fan (the kind you use to cool yourself off, not the PC), and it would be nice to be able to control it from the terminal, because I want to position the fan somewhere far away.
I suppose this could also be useful for a variety of other things as well, because there's a lot of USB toys out there. Maybe air purifiers, etc. (I heard they don't really work though).
According to the docs, there were several changes to the USB power management from kernels 2.6.32, which seem to settle in 2.6.38. Now you'll need to wait for the device to become idle, which is governed by the particular device driver. The driver needs to support it, otherwise the device will never reach this state. Unluckily, now the user has no chance to force this. However, if you're lucky and your device can become idle, then to turn this off you need to:
echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend"
echo "auto" > "/sys/bus/usb/devices/usbX/power/level"
or, for kernels around 2.6.38 and above:
echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend_delay_ms"
echo "auto" > "/sys/bus/usb/devices/usbX/power/control"
This literally means, go suspend at the moment the device becomes idle.
So unless your fan is something "intelligent" that can be seen as a device and controlled by a driver, you probably won't have much luck on current kernels.
Note. The information in this answer is relevant for the older kernels (up to 2.6.32). See tlwhitec's answer for the information on the newer kernels.
# disable external wake-up; do this only once
echo disabled > /sys/bus/usb/devices/usb1/power/wakeup
echo on > /sys/bus/usb/devices/usb1/power/level # turn on
echo suspend > /sys/bus/usb/devices/usb1/power/level # turn off
(You may need to change usb1 to usb n)
Source: Documentation/usb/power-management.txt.gz
PowerTOP from Intel allows you to toggle devices such as usb peripherals in real-time. These are called 'tunables'.
sudo apt install powertop
sudo powertop
Tab over to 'tunables'.
Scroll down to your device.
Hit enter to toggle power saving mode (Good/Bad)
Note that Bad means the device is always on. Toggling to Good will turn off the device after the preset inactive saving time (default is 2000ms).
See the PowerTOP docs for details on how to make these changes permanent.It generates the config scripts for you (pretty much as described by other posters on this thread).
NOTE: These scripts do not affect USB pin power (which is always on).
These only send the driver protocol to activate and deactivate a device.
If you want to control pin power, you could use either a supported smart USB hub, or better yet a microcontroller.
I have found these solutions that at least work for properly configured Terminus FE 1.1 USB hub chip:
1.To turn off power on all USB ports of a hub, you may unbind the hub from kernel using:
echo "1-4.4.4" > /sys/bus/usb/drivers/usb/unbind
to turn power back on - you may bind it back using
echo "1-4.4.4" > /sys/bus/usb/drivers/usb/bind
2.Switching power at each port individually is trickier: I was able to use hubpower to control each port - but it comes with a downside: hubpower first disconnects the usbdevfs wich causes all of the USB devices to disconect from system, at least on ubuntu:
usb_ioctl.ioctl_code = USBDEVFS_DISCONNECT;
rc = ioctl(fd, USBDEVFS_IOCTL, &usb_ioctl);
With this ioctl disabled I was able to switch off individual port power without detaching all devices - but the power goes back on immediately (probably due to kernel seeing an uninitialized device) which causes USB device just to do a "cold restart" which is what I generally wanted to do. My patched hubpower is here
You could use my tool uhubctl to control USB power per port for compatible USB hubs.
I wanted to do this, and with my USB hardware I couldn't. I wrote a hacky way how to do it here:
http://pintant.cat/2012/05/12/power-off-usb-device/ .
In a short way: I used a USB relay to open/close the VCC of another USB cable...
echo '2-1' |sudo tee /sys/bus/usb/drivers/usb/unbind
works for ubuntu
The reason why folks post questions such as this is due to the dreaded- indeed "EVIL"- USB Auto-Suspend "feature".
Auto suspend winds-down the power to an "idle" USB device and unless the device's driver supports this feature correctly, the device can become uncontactable. So powering a USB port on/off is a symptom of the problem, not the problem in itself.
I'll show you how to GLOBALLY disable auto-suspend, negating the need to manually toggle the USB ports on & off:
Short Answer:
You do NOT need to edit "autosuspend_delay_ms" individually: USB autosuspend can be disabled globally and PERSISTENTLY using the following commands:
sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT="/&usbcore.autosuspend=-1 /' /etc/default/grub
update-grub
systemctl reboot
An Ubuntu 18.04 screen-grab follows at the end of the "Long Answer" illustrating how my results were achieved.
Long Answer:
It's true that the USB Power Management Kernel Documentation states autosuspend is to be deprecated and in in its' place "autosuspend_delay_ms" used to disable USB autosuspend:
"In 2.6.38 the "autosuspend" file will be deprecated
and replaced by the "autosuspend_delay_ms" file."
HOWEVER my testing reveals that setting usbcore.autosuspend=-1 in /etc/default/grub as below can be used as a GLOBAL toggle for USB autosuspend functionality- you do NOT need to edit individual "autosuspend_delay_ms" files.
The same document linked above states a value of "0" is ENABLED and a negative value is DISABLED:
power/autosuspend_delay_ms
<snip> 0 means to autosuspend
as soon as the device becomes idle, and negative
values mean never to autosuspend. You can write a
number to the file to change the autosuspend
idle-delay time.
In the annotated Ubuntu 18.04 screen-grab below illustrating how my results were achieved (and reproducible), please remark the default is "0" (enabled) in autosuspend_delay_ms.
Then note that after ONLY setting usbcore.autosuspend=-1 in Grub, these values are now negative (disabled) after reboot. This will save me the bother of editing individual values and can now script disabling USB autosuspend.
Hope this makes disabling USB autosuspend a little easier and more scriptable-
I had a problem when connecting my android phone, I couldn't charge my phone because the power switch on and then off ...
PowerTop let me find this setting and was useful to fix the issue ( auto value was causing issue):
echo 'on' | sudo tee /sys/bus/usb/devices/1-1/power/control
USB 5v power is always on (even when the computer is turned off, on some computers and on some ports.) You will probably need to program an Arduino with some sort of switch, and control it via Serial library from USB plugged in to the computer.
In other words, a combination of this switch tutorial and this tutorial on communicating via Serial libary to Arduino plugged in via USB.
So far I came to the conclusion that you cannot control the power of a USB port. The 5V USB is always provided, and it's up to the device to use it or not. You can check this with a 5V fan or light.
I've tried various methods (disconnect/reconnect/bind/unbind/reset signal). Best so far are bind/unbind as it forces a cold restart of the device (but no power cycle).
I came up with a solution to reset USB devices, ports and controllers in a python script, which supports all of the above methods.
You can find the script at my Github page
Usage:
usb_reset.py -d 8086:1001 --reset-hub
The script uses among others the following solution to reset USB hubs/controllers:
Unbindind a USB port / controller works best via:
echo "myhub" > "/sys/bus/usb/drivers/usb/unbind"
echo "myhub" > "/sys/bus/usb/drivers/usb/bind"
Where myhub is found in /sys/bus/usb/devices/*
Or litteral controllers:
echo "mycontroller" > "/sys/bus/pci/drivers/unbind"
echo "mycontroller" > "/sys/bus/pci/drivers/bind"
Where mycontroller is found in /sys/bus/pci/drivers/[uoex]hci_hcd/*:*