svn commit: r301453 - in head/sys: arm/arm arm64/arm64 dev/fdt dev/gpio dev/iicbus dev/ofw dev/pci dev/vnic kern mips/mips sys

[John Baldwin]

On Thursday, July 21, 2016 01:37:42 PM Andrew Turner wrote:
> On Wed, 20 Jul 2016 13:28:53 +0200
> Michal Meloun <mmel at FreeBSD.org> wrote:
> > Dne 19.07.2016 v 17:06 Nathan Whitehorn napsal(a):
> > > 2. It partially duplicates the functionality of OFW_BUS_MAP_INTR(),
> > > but is both problematically more general and less flexible (it has
> > > requirements on timing of PIC attachment vs. driver resource
> > > allocation)  
> > OFW_BUS_MAP_INTR()  can parse only OFW  based data and expect that
> > parsed data are magicaly stored within the call.
> > The new method, bus_map_intr(),  can parse data from multiple sources 
> > (OFW, UEFI / ACPI, synthetic[gpio device + pin number]).  It also
> > returns parsed data back to caller.
> > And no, it  doesn't  add any additional timing requirements .
> 
> I've been looking at ACPI on arm64. So far I have not found the need
> for this with ACPI as we don't need to send the data to the interrupt
> controller driver to be parsed in the way OFW/FDT needs to.

ACPI though has a gross hack where we call BUS_CONFIG_INTR on the IRQ
in bus_alloc_resource().  What I had advocated in the discussions
leading up to this was to have some sort of opaque structure containing
a set of properties (the sort of thing bus_map_resource and make_dev_s
use) that was passed up at bus_setup_intr() time.  I think it should now
be passed up at bus_alloc_resource() time instead, but it would allow bus
drivers to "decorate" a SYS_RES_IRQ request as it goes up the device tree
with properties that the interrupt controller can then associate with
the IRQ cookie it allocates in its own code.  I would let the particular
structure have different layouts for different resource types.  On x86 we
would replace bus_config_intr by passing the level and trigger-mode in
this structure.  However, I could also see allowing the memattr to be
set for a SYS_RES_MEMORY resource so you could have a much shorter way
than an explicit bus_map_resource to map an entire BAR as WC for example:

    struct alloc_resource_args {
        size_t len;
        union {
            struct {
                enum intr_trigger trigger;
                enum intr_polarity polarity;
            } irq;
            struct {
                vm_memattr_t memattr;
            } memory;
        }
    }

...

    union alloc_resource_args args;

    init_alloc_resource_args(&args, sizeof(args));
    args.memattr = VM_MEMATTR_WRITE_COMBINING;

    /* Uses WC for the implicit mapping. */
    res = bus_alloc_resource(...., &args);

...

foobus_alloc_resource(..., union alloc_resource_args *args)
{
    union alloc_resource_args args2;

    switch (type) {
        case SYS_RES_IRQ:
            if (args == NULL) {
                init_alloc_resource_args(&args2, sizeof(args2));
                args = &args2;
            }
            /* Replace call to BUS_CONFIG_INTR on ACPI: */
            if (args->irq.polarity == INTR_POLARITY_CONFORMING &&
                device_has_polarity_from_CRS)
                args->irq.polarity = polarity_from_CRS;
            ...
}

However, you could associate arbitrary data with a resource request by
adding more members to the approriate struct in the union.

-- 
John Baldwin