Date:	Mon, 06 Jun 2016 17:54:47 -0400
From:	agustinv@...eaurora.org
To:	Marc Zyngier <marc.zyngier@....com>
Cc:	linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>, timur@...eaurora.org,
	cov@...eaurora.org, agross@...eaurora.org, harba@...eaurora.org,
	jcm@...hat.com, msalter@...hat.com, mlangsdo@...hat.com,
	ahs3@...hat.com, astone@...hat.com, graeme.gregory@...aro.org,
	guohanjun@...wei.com, charles.garcia-tobin@....com,
	marc.zyngier@...s.arm.com
Subject: Re: [PATCH V3 1/2] ACPI: Add support for ResourceSource/IRQ domain
 mapping

On 2016-06-04 08:30, Marc Zyngier wrote:
> On Fri, 13 May 2016 12:16:42 -0400
> Agustin Vega-Frias <agustinv@...eaurora.org> wrote:
> 
>> This allows irqchip drivers to associate an ACPI DSDT device to
>> an IRQ domain and provides support for using the ResourceSource
>> in Extended IRQ Resources to find the domain and map the IRQs
>> specified on that domain.
>> 
>> Signed-off-by: Agustin Vega-Frias <agustinv@...eaurora.org>
>> ---
>>  drivers/acpi/Makefile    |   1 +
>>  drivers/acpi/irqdomain.c | 108 
>> +++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/acpi/resource.c  |  23 ++++++----
>>  include/linux/acpi.h     |   6 +++
>>  4 files changed, 130 insertions(+), 8 deletions(-)
>>  create mode 100644 drivers/acpi/irqdomain.c
>> 
>> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
>> index b12fa64..79db78f 100644
>> --- a/drivers/acpi/Makefile
>> +++ b/drivers/acpi/Makefile
>> @@ -56,6 +56,7 @@ acpi-$(CONFIG_ACPI_NUMA)	+= numa.o
>>  acpi-$(CONFIG_ACPI_PROCFS_POWER) += cm_sbs.o
>>  acpi-y				+= acpi_lpat.o
>>  acpi-$(CONFIG_ACPI_GENERIC_GSI) += gsi.o
>> +acpi-y				+= irqdomain.o
>> 
>>  # These are (potentially) separate modules
>> 
>> diff --git a/drivers/acpi/irqdomain.c b/drivers/acpi/irqdomain.c
>> new file mode 100644
>> index 0000000..0fd10a9
>> --- /dev/null
>> +++ b/drivers/acpi/irqdomain.c
>> @@ -0,0 +1,108 @@
>> +/*
>> + * ACPI ResourceSource/IRQ domain mapping support
>> + *
>> + * Copyright (c) 2016, The Linux Foundation. All rights reserved.
>> + *
>> + * This program is free software; you can redistribute it and/or 
>> modify
>> + * it under the terms of the GNU General Public License version 2 and
>> + * only version 2 as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +#include <linux/acpi.h>
>> +#include <linux/irq.h>
>> +#include <linux/irqdomain.h>
>> +
>> +/**
>> + * acpi_irq_domain_register_irq() - Register the mapping for an IRQ 
>> produced
>> + *                                  by the given acpi_resource_source 
>> to a
>> + *                                  Linux IRQ number
>> + * @source: IRQ source
> 
> I'm a bit uncertain if this describe the interrupt producer (the device
> that shakes an interrupt line) or the interrupt collator (the device
> that presents a bunch of interrupts to a downstream element). I'm
> tempted to say that this is the latter, but that's far from being 
> clear.

That is correct, acpi_resource_source is a device that produces IRQs for 
other devices.

> 
>> + * @rcirq: IRQ number
>> + * @trigger: trigger type of the IRQ number to be mapped
>> + * @polarity: polarity of the IRQ to be mapped
> 
> So if I'm right in my above understanding, you've reinvented an
> existing abstraction (irq_fwspec).
> 
>> + *
>> + * Returns: a valid linux IRQ number on success
>> + *          -ENODEV if the given acpi_resource_source cannot be found
>> + *          -EPROBE_DEFER if the IRQ domain has not been registered
>> + *          -EINVAL for all other errors
>> + */
>> +int acpi_irq_domain_register_irq(struct acpi_resource_source *source, 
>> u32 rcirq,
>> +				 int trigger, int polarity)
>> +{
>> +	struct irq_domain *domain;
>> +	struct acpi_device *device;
>> +	acpi_handle handle;
>> +	acpi_status status;
>> +	unsigned int type;
>> +	int ret;
>> +
>> +	status = acpi_get_handle(NULL, source->string_ptr, &handle);
>> +	if (ACPI_FAILURE(status))
>> +		return -ENODEV;
>> +
>> +	device = acpi_bus_get_acpi_device(handle);
>> +	if (!device)
>> +		return -ENODEV;
>> +
> 
> So at this point, you should be able to create a irq_fwspec, and call
> into irq_create_fwspec_mapping(), without the need to open-code stuff
> we already have. And as a bonus point, you'd end-up with code that'd be
> similar to what is in gsi.c...
> 

Got it.

>> +	domain = irq_find_matching_fwnode(&device->fwnode, DOMAIN_BUS_ANY);
>> +	if (!domain) {
>> +		ret = -EPROBE_DEFER;
>> +		goto out_put_device;
>> +	}
>> +
>> +	type = acpi_dev_get_irq_type(trigger, polarity);
>> +	ret = irq_create_mapping(domain, rcirq);
>> +	if (ret)
>> +		irq_set_irq_type(ret, type);
>> +
>> +out_put_device:
>> +	acpi_bus_put_acpi_device(device);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(acpi_irq_domain_register_irq);
>> +
>> +/**
>> + * acpi_irq_domain_unregister_irq() - Delete the mapping for an IRQ 
>> produced
>> + *                                    by the given 
>> acpi_resource_source to a
>> + *                                    Linux IRQ number
>> + * @source: IRQ source
>> + * @rcirq: IRQ number
>> + *
>> + * Returns: 0 on success
>> + *          -ENODEV if the given acpi_resource_source cannot be found
>> + *          -EINVAL for all other errors
>> + */
>> +int acpi_irq_domain_unregister_irq(struct acpi_resource_source 
>> *source,
>> +				   u32 rcirq)
>> +{
>> +	struct irq_domain *domain;
>> +	struct acpi_device *device;
>> +	acpi_handle handle;
>> +	acpi_status status;
>> +	int ret = 0;
>> +
>> +	status = acpi_get_handle(NULL, source->string_ptr, &handle);
>> +	if (ACPI_FAILURE(status))
>> +		return -ENODEV;
>> +
>> +	device = acpi_bus_get_acpi_device(handle);
>> +	if (!device)
>> +		return -ENODEV;
>> +
>> +	domain = irq_find_matching_fwnode(&device->fwnode, DOMAIN_BUS_ANY);
>> +	if (!domain) {
>> +		ret = -EINVAL;
>> +		goto out_put_device;
>> +	}
>> +
>> +	irq_dispose_mapping(irq_find_mapping(domain, rcirq));
>> +
>> +out_put_device:
>> +	acpi_bus_put_acpi_device(device);
>> +	return ret;
>> +}
> 
> Again, this smell a lot like gsi.c, with added sugar on top.

Yes, this can go away since a client can just call irq_dispose_mapping 
which finds the domain from the irq_data.

> 
>> +EXPORT_SYMBOL_GPL(acpi_irq_domain_unregister_irq);
>> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
>> index 56241eb..1551698 100644
>> --- a/drivers/acpi/resource.c
>> +++ b/drivers/acpi/resource.c
>> @@ -381,14 +381,15 @@ static void acpi_dev_irqresource_disabled(struct 
>> resource *res, u32 gsi)
>>  	res->flags = IORESOURCE_IRQ | IORESOURCE_DISABLED | 
>> IORESOURCE_UNSET;
>>  }
>> 
>> -static void acpi_dev_get_irqresource(struct resource *res, u32 gsi,
>> +static void acpi_dev_get_irqresource(struct resource *res, u32 rcirq,
>> +				     struct acpi_resource_source *source,
>>  				     u8 triggering, u8 polarity, u8 shareable,
>>  				     bool legacy)
>>  {
>>  	int irq, p, t;
>> 
>> -	if (!valid_IRQ(gsi)) {
>> -		acpi_dev_irqresource_disabled(res, gsi);
>> +	if ((source->string_length == 0) && !valid_IRQ(rcirq)) {
>> +		acpi_dev_irqresource_disabled(res, rcirq);
>>  		return;
>>  	}
>> 
>> @@ -402,12 +403,12 @@ static void acpi_dev_get_irqresource(struct 
>> resource *res, u32 gsi,
>>  	 * using extended IRQ descriptors we take the IRQ configuration
>>  	 * from _CRS directly.
>>  	 */
>> -	if (legacy && !acpi_get_override_irq(gsi, &t, &p)) {
>> +	if (legacy && !acpi_get_override_irq(rcirq, &t, &p)) {
>>  		u8 trig = t ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
>>  		u8 pol = p ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
>> 
>>  		if (triggering != trig || polarity != pol) {
>> -			pr_warning("ACPI: IRQ %d override to %s, %s\n", gsi,
>> +			pr_warning("ACPI: IRQ %d override to %s, %s\n", rcirq,
>>  				   t ? "level" : "edge", p ? "low" : "high");
>>  			triggering = trig;
>>  			polarity = pol;
>> @@ -415,12 +416,16 @@ static void acpi_dev_get_irqresource(struct 
>> resource *res, u32 gsi,
>>  	}
>> 
>>  	res->flags = acpi_dev_irq_flags(triggering, polarity, shareable);
>> -	irq = acpi_register_gsi(NULL, gsi, triggering, polarity);
>> +	if (source->string_length > 0)
>> +		irq = acpi_irq_domain_register_irq(source, rcirq, triggering,
>> +						   polarity);
>> +	else
>> +		irq = acpi_register_gsi(NULL, rcirq, triggering, polarity);
> 
> Do you see what I mean about these being similar?
> 
>>  	if (irq >= 0) {
>>  		res->start = irq;
>>  		res->end = irq;
>>  	} else {
>> -		acpi_dev_irqresource_disabled(res, gsi);
>> +		acpi_dev_irqresource_disabled(res, rcirq);
>>  	}
>>  }
>> 
>> @@ -448,6 +453,7 @@ bool acpi_dev_resource_interrupt(struct 
>> acpi_resource *ares, int index,
>>  {
>>  	struct acpi_resource_irq *irq;
>>  	struct acpi_resource_extended_irq *ext_irq;
>> +	struct acpi_resource_source dummy = { 0, 0, NULL };
>> 
>>  	switch (ares->type) {
>>  	case ACPI_RESOURCE_TYPE_IRQ:
>> @@ -460,7 +466,7 @@ bool acpi_dev_resource_interrupt(struct 
>> acpi_resource *ares, int index,
>>  			acpi_dev_irqresource_disabled(res, 0);
>>  			return false;
>>  		}
>> -		acpi_dev_get_irqresource(res, irq->interrupts[index],
>> +		acpi_dev_get_irqresource(res, irq->interrupts[index], &dummy,
>>  					 irq->triggering, irq->polarity,
>>  					 irq->sharable, true);
>>  		break;
>> @@ -471,6 +477,7 @@ bool acpi_dev_resource_interrupt(struct 
>> acpi_resource *ares, int index,
>>  			return false;
>>  		}
>>  		acpi_dev_get_irqresource(res, ext_irq->interrupts[index],
>> +					 &ext_irq->resource_source,
>>  					 ext_irq->triggering, ext_irq->polarity,
>>  					 ext_irq->sharable, false);
>>  		break;
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index 06ed7e5..f4f515e 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -26,6 +26,7 @@
>>  #include <linux/resource_ext.h>
>>  #include <linux/device.h>
>>  #include <linux/property.h>
>> +#include <linux/irqdomain.h>
>> 
>>  #ifndef _LINUX
>>  #define _LINUX
>> @@ -294,6 +295,11 @@ int acpi_isa_irq_to_gsi (unsigned isa_irq, u32 
>> *gsi);
>>  void acpi_set_irq_model(enum acpi_irq_model_id model,
>>  			struct fwnode_handle *fwnode);
>> 
>> +int acpi_irq_domain_register_irq(struct acpi_resource_source *source, 
>> u32 rcirq,
>> +		      int trigger, int polarity);
>> +int acpi_irq_domain_unregister_irq(struct acpi_resource_source 
>> *source,
>> +				   u32 rcirq);
>> +
>>  #ifdef CONFIG_X86_IO_APIC
>>  extern int acpi_get_override_irq(u32 gsi, int *trigger, int 
>> *polarity);
>>  #else
> 
> Thanks,
> 
> 	M.
> --
> Jazz is not dead. It just smells funny.

Thanks.

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum,
a Linux Foundation Collaborative Project.

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