Date: Thu, 15 Jan 2015 23:42:53 +0100 From: Svatopluk Kraus <onwahe@gmail.com> To: Nathan Whitehorn <nwhitehorn@freebsd.org> Cc: freebsd-arm@freebsd.org Subject: Re: interrupt framework Message-ID: <CAFHCsPXfKw6Cf1Mjqr=acwSYrs-5gu1Bs1bXK0n6prTo65LNVA@mail.gmail.com> In-Reply-To: <54B7EB67.6010702@freebsd.org> References: <CAFHCsPX5kG_v-F-cjpyMQsT_b386eok=mqWW0%2BEUb_4-_1Otnw@mail.gmail.com> <54B7EB67.6010702@freebsd.org>
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On Thu, Jan 15, 2015 at 5:31 PM, Nathan Whitehorn <nwhitehorn@freebsd.org> wrote: > > On 01/15/15 05:51, Svatopluk Kraus wrote: >> >> Hi community, >> >> I and Michal Meloun have done some work on ARM interrupt framework and >> this is the result. >> >> We've started with intrng project with Ian's WIP changes, have looked >> at Andrew's ARM64 git repository, and this is how we think an >> interrupt framework should look like. We've implemented it with >> removable interrupt controllers in mind (PCI world). It's not finished >> from this point of view, however some functions are more complex >> because of it. >> >> It's tested on pandaboard and only GIC is implemented now. There is no >> problem to implement it to other controllers. We are open to questions >> and can finish our work considering any comments. Whoever is waiting >> for ARM interrupt framework as we were, you are welcome to test it. >> Whoever is welcome. The patches are done against FreeBSD-11-current >> revision 277210. There are two new files. >> >> ARM_INTRNG option must be added to board configuration file for new >> framework. >> >> There are still some things not implemented and some things which >> should be discussed like PPI support. For example, how to enable PPI >> interrupt on other CPUs when they are already running? >> >> We keep in mind that an interrupt framework should be helpfull but >> general enough to not dictate interrupt controlles too much. Thus we >> try to keep some things as much separated as possible. Each interrupt >> is represented by an interrupt source (ISRC) in the framework. An ISRC >> is described by an interrupt number which is much more an unique >> resource handle - totally independent on internal representation of >> interrupts in any interrupt controller. > > > This is a good design. > >> An interrupt is described by cells in FDT world. The cells can be >> decoded only by associated interrupt controller and as such, they are >> transparent for interrupt framework. The framework provides >> arm_fdt_map_irq() function which maps this transparent cells to an >> interrupt number. It creates an ISRC, saves cells on it, and once when >> associated interrupt controller is registered, it provides the ISRC >> with cells into the controller. >> >> It's a controller responsibility to save an ISRC associated with >> cells. An ISRC is transparent for any controller. However, an >> controller can set/get its data to/from an ISRC. Further, an >> controller should set a name to an ISRC according to internal >> representation of associated interrupt. > > > I'm assuming you are referring to arm_describe_irq? I had three comments on > that: > 1. Can you please make it part of the same API as ofw_bus_map_irq() rather > than an out-of-band thing? This will let other platforms use it. > 2. Once you've done that, you can remove all the #ifdef from simplebus. I > would strongly prefer it not gain platform-specific #ifdef. > 3. We should not be adding new things to machine/fdt.h unless they are > really internal platforms APIs for reading the FDT. And even then, the > header should probably disappear soon. FDT_MAP_IRQ() is used only in > arm/intr.c, for example, and should be replaced by a direct invocation of > arm_fdt_map_intr(). arm_describe_irq() should not join it there. > Hmm, we was not aware of that as we have taken something what was already designed this way. However, it's not problem to arrange things according to you comments. >> An controller interrupt dispatch function can call framework only if >> it has associated ISRC to received interrupt. >> >> For legacy reason, there is arm_namespace_map_irq() function. An >> interrupt is described by namespace type and a number from the >> namespace. It's intented for use with no FDT drivers. Now, it's used >> for mapping an IPI on a controller. >> >> We think that it's better to call chained controllers (with filter >> only) without MI interrupt framework overhead, so we implemented >> shortcut. It could be utilized by INTR_SOLO flag during >> bus_setup_intr(). > > > Can you describe the shortcut? We never ended up needing something like this > on PowerPC. > In standard MI interrupt framework, an interrupt event is created for an interrupt and intr_event_handle() is called to handle an interrupt when it comes. Many things happen in this functions before real filters and/or handlers are called. In former design, when controllers are chained, it's done on each of them - on each layer. So if a controller is fast enough and handles interrupts by a filter, we can call the filter without MI framework overhead. Thus we save time and stack space. And we do not have a problem to pass trapframe thru chained controllers. Further, it can be utilized by any interrupt where time is critical. >> Only an interrupt controller can really know its position in interrupt >> controller's tree. So root controller must claim itself as a root. In >> FDT world, according to ePAPR approved version 1.1 from 08 April 2011, >> page 30: >> >> "The root of the interrupt tree is determined when traversal of the >> interrupt tree reaches an interrupt controller node without an >> interrupts property and thus no explicit interrupt parent." >> >> Thus there are no need for any non-standard things in DTS files. > > > Right, this is what we did on PPC. > -Nathan > >> Svata >> >> >> _______________________________________________ >> freebsd-arm@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-arm >> To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org" > > > _______________________________________________ > freebsd-arm@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-arm > To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org"
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