[RFC,v2,10/11] irqchip: mbigen: Add ACPI support

From: Hanjun Guo <hanjun.guo@linaro.org>


With the preparation of platform msi support and interrupt producer
in DSDT, we can add mbigen ACPI support now.

We are using _PRS methd to indicate number of irq pins instead
of num_pins in DT.

For mbi-gen,
    Device(MBI0) {
          Name(_HID, "HISI0152")
          Name(_UID, Zero)
          Name(_CRS, ResourceTemplate() {
                  Memory32Fixed(ReadWrite, 0xa0080000, 0x10000)
          })

          Name (_PRS, ResourceTemplate() {
		  Interrupt(ResourceProducer,...) {12,14,....}
          })
    }

For devices,

   Device(COM0) {
          Name(_HID, "ACPIIDxx")
          Name(_UID, Zero)
          Name(_CRS, ResourceTemplate() {
                 Memory32Fixed(ReadWrite, 0xb0030000, 0x10000)
		 Interrupt(ResourceConsumer,..., "\_SB.MBI0") {12}
          })
    }

With the helpe of platform msi and interrupt producer, then devices
will get the virq from mbi-gen's irqdomain.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ma Jun <majun258@huawei.com>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>

---
 drivers/irqchip/irq-mbigen.c | 70 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 67 insertions(+), 3 deletions(-)

-- 
1.7.12.4

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Hi Marc,

On 2016/9/15 16:49, Marc Zyngier wrote:
> On 14/09/16 15:21, Hanjun Guo wrote:

>> From: Hanjun Guo <hanjun.guo@linaro.org>

>>

>> With the preparation of platform msi support and interrupt producer

>> in DSDT, we can add mbigen ACPI support now.

>>

>> We are using _PRS methd to indicate number of irq pins instead

>> of num_pins in DT.

>>

>> For mbi-gen,

>>     Device(MBI0) {

>>           Name(_HID, "HISI0152")

>>           Name(_UID, Zero)

>>           Name(_CRS, ResourceTemplate() {

>>                   Memory32Fixed(ReadWrite, 0xa0080000, 0x10000)

>>           })

>>

>>           Name (_PRS, ResourceTemplate() {

>> 		  Interrupt(ResourceProducer,...) {12,14,....}

>>           })

>

> Since I know next to nothing about all of this, I'm going to play the

> village idiot. What makes it legal to use _PRS as a way to describe the

> interrupts that are exposed by MBI0? Looking at the 6.0 spec, I do not

> see why the interrupts would be put there instead of _CRS, and why you'd

> have a _PRS at all.


_PRS describes possible resource settings for the device, which returns
a list of a device's possible resource settings such as memory range,
interrupt descriptors, and the format of the data in a _PRS object
follows the same format as _CRS object (ACPI 6.1, section 6.2.12),
so Interrupts can be put in the _PRS.

And in ACPI 6.1, section 6.2, it describes the _PRS usage:

"Some resources, however, may be shared amongst several devices. To
describe this, devices that share a resource (resource consumers) must
use the extended resource descriptors (0x7-0xA) described in Section
6.4.3, “Large Resource Data Type.” These descriptors point to a single
device object (resource producer) that claims the shared resource in
its _PRS."

As mbigen is a interrupt producer which provide interrupt resoures
for devices, which matches the usage of _PRS in the spec.

>

> Also, are you going to exhaustively describe all the possible interrupts

> via this method? Knowing that the mbigen can expose thousands of

> interrupts, I find it slightly mad. Can't you express a range?


Yes, a little bit mad. I can't express a interrupt range in ACPI at
least in current version of spec. But that just adding more lines
of ACPI DSDT code, it's fine to me. or we need to use _DSD to present
similar property "num_pins" in ACPI which I avoid using.

Thanks
Hanjun
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