linux-kernel - Re: [PATCH v3 11/17] ARM64 / ACPI: Introduce ACPI_IRQ_MODEL

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Date:	Thu, 11 Sep 2014 12:34:33 +0100
From:	Grant Likely <grant.likely@...aro.org>
To:	Hanjun Guo <hanjun.guo@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mark Rutland <mark.rutland@....com>,
	Olof Johansson <olof@...om.net>
Cc:	Graeme Gregory <graeme.gregory@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	Sudeep Holla <Sudeep.Holla@....com>,
	Will Deacon <will.deacon@....com>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
	Robert Richter <rric@...nel.org>,
	Lv Zheng <lv.zheng@...el.com>,
	Robert Moore <robert.moore@...el.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Charles Garcia-Tobin <Charles.Garcia-Tobin@....com>,
	ACPI Devel Mailing List <linux-acpi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linaro-acpi <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH v3 11/17] ARM64 / ACPI: Introduce ACPI_IRQ_MODEL_GIC and
 register device's gsi

On Thu, Sep 11, 2014 at 12:08 PM, Grant Likely <grant.likely@...aro.org> wrote:
> On Mon,  1 Sep 2014 22:57:49 +0800, Hanjun Guo <hanjun.guo@...aro.org> wrote:
>> Introduce ACPI_IRQ_MODEL_GIC which is needed for ARM64 as GIC is
>> used, and then register device's gsi with the core IRQ subsystem.
>>
>> acpi_register_gsi() is similar to DT based irq_of_parse_and_map(),
>> since gsi is unique in the system, so use hwirq number directly
>> for the mapping.
>>
>> Originally-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
>> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
>> ---
>>  arch/arm64/kernel/acpi.c |   73 ++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/acpi/bus.c       |    3 ++
>>  include/linux/acpi.h     |    1 +
>>  3 files changed, 77 insertions(+)
>>
>> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
>> index 35dff11..354b912 100644
>> --- a/arch/arm64/kernel/acpi.c
>> +++ b/arch/arm64/kernel/acpi.c
>> @@ -37,6 +37,12 @@ EXPORT_SYMBOL(acpi_pci_disabled);
>>  static int enabled_cpus;     /* Processors (GICC) with enabled flag in MADT */
>>
>>  /*
>> + * Since we're on ARM, the default interrupt routing model
>> + * clearly has to be GIC.
>> + */
>> +enum acpi_irq_model_id acpi_irq_model = ACPI_IRQ_MODEL_GIC;
>> +
>> +/*
>>   * __acpi_map_table() will be called before page_init(), so early_ioremap()
>>   * or early_memremap() should be called here to for ACPI table mapping.
>>   */
>> @@ -194,6 +200,73 @@ void __init acpi_smp_init_cpus(void)
>>       pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus);
>>  }
>>
>> +int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
>> +{
>> +     *irq = irq_find_mapping(NULL, gsi);
>> +
>> +     return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
>
> Why is this exported? x86 exports it, but ia64 does not. There aren't
> very many callers, and none of them can be built as a module AFAICS.
>
>> +
>> +/*
>> + * success: return IRQ number (>0)
>> + * failure: return =< 0
>> + */
>> +int acpi_register_gsi(struct device *dev, u32 gsi, int trigger, int polarity)
>> +{
>> +     unsigned int irq;
>> +     unsigned int irq_type;
>> +
>> +     /*
>> +      * ACPI have no bindings to indicate SPI or PPI, so we
>> +      * use different mappings from DT in ACPI.
>> +      *
>> +      * For FDT
>> +      * PPI interrupt: in the range [0, 15];
>> +      * SPI interrupt: in the range [0, 987];
>> +      *
>> +      * For ACPI, GSI should be unique so using
>> +      * the hwirq directly for the mapping:
>> +      * PPI interrupt: in the range [16, 31];
>> +      * SPI interrupt: in the range [32, 1019];
>> +      */
>
> Hmmm, so doing it this way means that DT systems will have a different
> irq_domain setup compared with ACPI systems. I'm not convinced we want
> to do that, but I need to look at the code that sets up the new domains
> before I comment further...

Okay, nevermind. I looked at the setup code. This isn't an issue of
the irq domain being set up differently, but rather the binding
translation operates differently between DT and ACPI. ACPI used a
single integer encapsulating PPI and SPI which just happens to line up
with the hwirq numbers, whereas DT uses a [type,number] tuple that
needs translating into the hwirq. This code is fine.

g.
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