Messages in this thread | | | Date | Sun, 08 Sep 2013 18:50:15 -0500 | From | Daniel Santos <> | Subject | Re: "Virtual" Interrupts -- Need help please |
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On 09/07/2013 07:52 PM, Guenter Roeck wrote: > On 09/07/2013 05:19 PM, Daniel Santos wrote: >> I've posted a number of requests for aid on this and have gotten very >> little responses and none that were helpful. I have spent at least 24 >> hours of research time on this and just a little direction from >> somebody who knows this subsystem can help me immensely as the IRQ >> subsystem is new to me. >> >> This is for the MCP2210 driver (a USB to SPI/GPIO bridge) and my >> driver is the first of its class for the Linux kernel, giving me less >> to look at as an example. I intend to use standard drivers for >> whatever I have connected at the other end. For this to work, I need >> to supply interrupts for some of these drivers to work correctly. >> How do I do this? Every thing else on this driver is ready to go and >> my handler functions for this are empty and waiting for some code. >> > Not really. Have a look at https://github.com/groeck/diolan even > though the SPI part there > still isn't working and it is far from being acceptable upstream in > its current form. > It also doesn't support interrupts.
Oh, this is wonderful to know! While I like breaking new ground, I certainly don't enjoy doing it when I'm trying to write my first device driver and having to learn so many new things.
> > It is modeled as mfd driver, which I think you might want to consider > as well. > >> So do i create an IRQ domain and then call generic_handle_irq() from >> my URB complete() function? If so, which type of IRQ Domain is >> appropriate for this? Unlike typical platform devices, these are >> dynamically added and removed throughout the life of the kernel, >> adding to the challenge. So, if I understand correctly, my base IRQ >> number needs to be dynamically generated. How should I manage this? >> >> Finally, if you have any example drivers that are doing something >> similar, that would be SO very helpful as well! >> > There are several drivers in drivers/mfd solving the same problem, ie > using > irq domains to pass interrupts to client drivers. Look for > irq_domain_add_simple(). > drivers/mfd/tc3589x.c seems to be a good example.
Ahh, wonderful! I was looking at a lot of the code in mfd, but it contains so many things that I don't understand yet, so it's been harder to be clear on what the driver is doing and why w/o extensive examination & study of the subsystems it's using. This will help!
> >> I have some secondary (and less important) questions about how to >> integrate this with device drivers that want a DT / open firmware >> config (which I know almost nothing about at this time), but that can >> wait. >> > If you look into the mfd subsystem, you may notice that it handles at > least some of the complexity > of interrupt handling as well as devicetree integration. One more > reason to use it. > > Guenter
Even better, thank you very much!! If this thing had more EEPROM storage I would consider using the OF format for it's settings, but I only have 256 bytes to play with so I'm using a custom compression/encoding.
I'm hoping to present this for an initial review in a month or so. I'm sure you guys will shred it, but I'm excited about it anyway! :)
Thanks again! Daniel
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