Date: Mon, 19 Jan 2015 15:47:32 -0800 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Svatopluk Kraus <onwahe@gmail.com> Cc: freebsd-arm@freebsd.org Subject: Re: interrupt framework Message-ID: <54BD9794.4080204@freebsd.org> In-Reply-To: <CAFHCsPUqq-o4z9c5_8SYxcefUiFvGADB5FnB5NiQuu6XBrdyng@mail.gmail.com> References: <CAFHCsPX5kG_v-F-cjpyMQsT_b386eok=mqWW0%2BEUb_4-_1Otnw@mail.gmail.com> <54BA9888.1020303@freebsd.org> <CAFHCsPX-X-OG4jGLbhdH1BVtqorJKUeaVbzabX-%2BUfEM2fhD6A@mail.gmail.com> <54BD3F86.3010901@freebsd.org> <CAFHCsPUqq-o4z9c5_8SYxcefUiFvGADB5FnB5NiQuu6XBrdyng@mail.gmail.com>
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On 01/19/15 15:00, Svatopluk Kraus wrote: > On Mon, Jan 19, 2015 at 6:31 PM, Nathan Whitehorn > <nwhitehorn@freebsd.org> wrote: >> On 01/19/15 08:42, Svatopluk Kraus wrote: >>> On Sat, Jan 17, 2015 at 6:14 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. >>>>> >>>>> 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. >>>>> >>>>> 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(). >>>>> >>>>> 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. >>>>> >>>>> Svata >>>>> >>>> I took a look through intrng.c and had a couple comments about the FDT >>>> mapping stuff: >>>> >>>> 1. You use the device tree node handles as lookup keys rather than xref >>>> handles. These are not necessarily stable, so you should use xref handles >>>> instead. >>>> >>>> 2. If you make change (1), you don't depend on any OF_* stuff and can use >>>> the same code with the PIC node ID as an opaque key on non-FDT platforms. >>>> We >>>> do this on PowerPC as well, which has been very useful. It will also save >>>> some #ifdef. >>>> -Nathan >>>> >>> Thanks. I did changes due to (1). Considering (2), I understand what >>> you are doing in PowerPC, but it's not something I could adapt so >>> easily. Hiding phandle_t behind uint32_t is clever, saves a few FDT >>> #ifdefs, but makes things a little mysterious. Even if we will think >>> about this uint32_t like some kind of key, there should be a function >>> which convert phandle_t to that uint32_t key. >>> >>> I'm attaching new version of intrng.c with change (1) and with some >>> more little adjustments. >>> >>> Svata >> >> Thanks! How do you plan to support multiple PICs on non-FDT platforms then? >> It looks like it just fails at the moment. >> -Nathan > > There is the following mapping function: > u_int arm_namespace_map_irq(device_t dev, uint8_t type, uint16_t num); > > I named it "namespace" but it can be named another way. I think it > does same like in PowerPC when node is NULL. However, there is one > more argument - type. For example, it's used for IPI mapping in > intrng.c. > > Svata > So you need the PIC's device_t to allocate an interrupt? That doesn't seem workable in the real world. What's wrong with just exposing the FDT interface with the phandle_t as an opaque key? You don't do anything with it except use it as a table lookup key, so it does not in any way matter what it actually is. -Nathan
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