On Thursday, July 21, 2016 01:37:42 PM Andrew Turner wrote:
> On Wed, 20 Jul 2016 13:28:53 +0200
> Michal Meloun <m...@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
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