Subject: [PATCH 5/5] irqchip: GIC: Switch ACPI support to stacked domains

From: [email-masked] (Hanjun Guo)
Date: Wed, 22 Jul 2015 17:33:07 +0800

On 07/22/2015 04:53 PM, Marc Zyngier wrote:
> On 22/07/15 09:35, Hanjun Guo wrote:
>> On 07/22/2015 02:12 AM, Marc Zyngier wrote:
>>> On 21/07/15 19:05, Lorenzo Pieralisi wrote:
>>>> On Tue, Jul 21, 2015 at 11:08:00AM +0100, Marc Zyngier wrote:
>>>>> Now that the basic ACPI GSI code is irq domain aware, make sure
>>>>> that the ACPI support in the GIC doesn't pointlessly deviate from
>>>>> the DT path.
>>>>>
>>>>> Signed-off-by: Marc Zyngier <[email-masked]>
>>>>> ---
>>>>>    drivers/irqchip/irq-gic.c       | 17 ++++++-----------
>>>>>    include/linux/irqchip/arm-gic.h |  2 +-
>>>>>    2 files changed, 7 insertions(+), 12 deletions(-)
>>>>>
>>>>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>>>>> index b41ccf5..f5d365d 100644
>>>>> --- a/drivers/irqchip/irq-gic.c
>>>>> +++ b/drivers/irqchip/irq-gic.c
>>>>> @@ -813,8 +813,6 @@ static int gic_irq_domain_xlate(struct irq_domain *d,
>>>>>    {
>>>>>    	unsigned long ret = 0;
>>>>>
>>>>> -	if (irq_domain_get_of_node(d) != controller)
>>>>> -		return -EINVAL;
>>>>>    	if (intsize < 3)
>>>>>    		return -EINVAL;
>>>>>
>>>>> @@ -887,7 +885,7 @@ void gic_set_irqchip_flags(unsigned long flags)
>>>>>
>>>>>    void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>>>>>    			   void __iomem *dist_base, void __iomem *cpu_base,
>>>>> -			   u32 percpu_offset, struct device_node *node)
>>>>> +			   u32 percpu_offset, void *domain_token)
>>>>>    {
>>>>>    	irq_hw_number_t hwirq_base;
>>>>>    	struct gic_chip_data *gic;
>>>>> @@ -946,8 +944,8 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>>>>>    		gic_irqs = 1020;
>>>>>    	gic->gic_irqs = gic_irqs;
>>>>>
>>>>> -	if (node) {		/* DT case */
>>>>> -		gic->domain = irq_domain_add_linear(node, gic_irqs,
>>>>> +	if (domain_token) {		/* DT/ACPI case */
>>>>> +		gic->domain = irq_domain_add_linear(domain_token, gic_irqs,
>>>>>    						    &gic_irq_domain_hierarchy_ops,
>>>>>    						    gic);
>>>>>    	} else {		/* Non-DT case */
>>>>> @@ -973,7 +971,7 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
>>>>>    			irq_base = irq_start;
>>>>>    		}
>>>>>
>>>>> -		gic->domain = irq_domain_add_legacy(node, gic_irqs, irq_base,
>>>>> +		gic->domain = irq_domain_add_legacy(NULL, gic_irqs, irq_base,
>>>>>    					hwirq_base, &gic_irq_domain_ops, gic);
>>>>>    	}
>>>>>
>>>>> @@ -1132,12 +1130,9 @@ gic_v2_acpi_init(struct acpi_table_header *table)
>>>>>    	}
>>>>>
>>>>>    	/*
>>>>> -	 * Initialize zero GIC instance (no multi-GIC support). Also, set GIC
>>>>> -	 * as default IRQ domain to allow for GSI registration and GSI to IRQ
>>>>> -	 * number translation (see acpi_register_gsi() and acpi_gsi_to_irq()).
>>>>> +	 * Initialize zero GIC instance (no multi-GIC support).
>>>>>    	 */
>>>>> -	gic_init_bases(0, -1, dist_base, cpu_base, 0, NULL);
>>>>> -	irq_set_default_host(gic_data[0].domain);
>>>>> +	gic_init_bases(0, -1, dist_base, cpu_base, 0, (void *)ACPI_IRQ_MODEL_GIC);
>>>>
>>>> Nit: the acpi_irq_model_id enum starts from 0, I do not think we will
>>>> use the IRQ domain look-up for the ACPI_IRQ_MODEL_PIC but we have
>>>> to be careful anyway.
>>>
>>> Yeah, I noticed that one too, but couldn't imagine the PIC being
>>> migrated to that model just yet. It looks like it would be pretty
>>> harmless to set ACPI_IRQ_MODEL_PIC to 1, and introduce
>>> ACPI_IRQ_MODEL_ILLEGAL as zero.
>>
>> I think this will be a problem, because acpi_irq_model_id enum actually
>> is defined by the ACPI spec, and the value is used to report to BIOS
>> the current interrupt model used by OS, see section 5.8.1 _PIC Method
>> in ACPI 6.0:
>>
>> 0 ? PIC mode
>> 1 ? APIC mode
>> 2 ? SAPIC mode
>> Other values ?Reserved
>
> Ah, right.
>
>> so we can't set ACPI_IRQ_MODEL_PIC to 1 as it may break the firmware,
>> also _PIC method actually is not needed for ARM platform at all, we
>> don't need to report to firmware the interrupt model used by OS on
>> ARM, it only used by legacy IA platforms, actually I'm planning to
>> remove acpi_irq_model_id on ARM64.
>
> Remove? I don't get it. Either ACPI_IRQ_MODEL_GIC is a leval value, and
> you can't remove it, or it is not, and I wonder how it ended up here the
> first place.

The best solution is that we don't call _PIC method on ARM at all
(acpi_irq_model is used for _PIC method), but we can live with it since
there is no harm if ARM firmware don't care about the value or ARM
firmware don't define _PIC method in DSDT.

>
>> So to me acpi_irq_model_id is suitable for the token, can we use
>                               is *not* ?
>> another one as the token? how about the GIC ID in the MADT table?
>> and this also can be used for x86 (IOAPIC IDs) too.
>
> You can use whatever you want, just not a pointer. I'll add a token
> parameter to the acpi_set_irq_model function that I mentioned in my
> reply to Lorenzo.

Thank you, I will wait for the v2 to rebase my ACPI GICv3 patches.

Thanks
Hanjun