Date: Mon, 18 Feb 2019 10:26:26 +0100 From: Hans Petter Selasky <hps@selasky.org> To: "Apollo D. Sharpe, Sr." <demetrioussharpe@netscape.net>, freebsd-usb@freebsd.org Subject: Re: Questions about the USB HID device drivers Message-ID: <0cbc66cd-9007-878e-8bc3-f623364729d4@selasky.org> In-Reply-To: <3724cc29-b682-2395-bd95-cbfa418ad9f2@netscape.net> References: <fd7883c8-604e-e7d7-b135-d1d957938e7c@netscape.net> <9c6a87dd-cf7c-d0eb-82f1-5e904baaf05f@selasky.org> <325834a2-d9f1-a1f4-dff1-7f724aeb4907@netscape.net> <6762c7c9-f9dc-f7d2-0b1f-c2f6e2816cd7@selasky.org> <3724cc29-b682-2395-bd95-cbfa418ad9f2@netscape.net>
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On 2/17/19 11:00 PM, Apollo D. Sharpe, Sr. wrote: > On 2/15/19 7:46 AM, Hans Petter Selasky wrote: >> On 2/15/19 2:22 PM, A. D. Sharpe wrote: >>> On 2/15/2019 3:30 AM, Hans Petter Selasky wrote: >>>> >>>> Did you have a look at the code? >>>> >>>> sys/dev/usb/input/ums.c and sys/dev/usb/input/ukbd.c >>> I think I have a decent understanding of USB devices under FreeBSD. >>> However, two things are tripping me up: a) the fact that the ums & >>> ukbd drivers don't have "make_dev()" calls in them; and b) I can't >>> seem to find an overall keyboard system or overall mouse system. >>> >> >> Events are delivered from the USB INTERRUPT endpoint's completion >> handler to various places. At the moment events can end up via EVDEV >> or simply sysmouse or the regular keyboard API depending on the system >> configuration. >> >> At the moment, only for EVDEVS's /dev/input/xxxx, there is a >> per-device character device handle, I think. > > > I think I've gotten a pretty good understanding of what's going on now, > based on the answers that I've gotten from the developers part of the > FreeBSD forums(*). The USB keyboard and mouse paths seems to go like this: > > ums->usb_hid->/dev/ums0->sysmouse > > ukbd->usb_hid->/dev/ukbd0->kbdmux > > > If this is correct, then the majority of my inquiry has been satisfied. > My next questions are more centered around /dev as it relates to device > drivers in general: > Hi, > 1. Is there a published standard of how device drivers should publish > themselves in /dev? From what I can tell, they seem to be thrown into > /dev without any sort of hierarchy to organize the nodes into what type > of device they represent. Each devicename has a uniq prefix followed by a uniq unit number. > > 2. Does usb_hid automatically dump device nodes into /dev, or is there a > way for hid drivers to specify specifically where their nodes should be > publish -such as: /dev/input/somehiddevice0 ? > Character device nodes are automatically created. However it is possible for user-space applications to create symbolic links afterwards in /dev . > > (*) > https://forums.freebsd.org/threads/questions-about-the-usb-hid-device-drivers.69604/ > --HPS
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