Re: [PATCH v9 16/21] irqchip: Add GICv2 specific ACPI boot support

[Catalin Marinas <catalin.marinas@arm.com>]

On Wed, Mar 04, 2015 at 11:50:36PM +0100, Rafael J. Wysocki wrote:
> On Wednesday, February 25, 2015 04:39:56 PM Hanjun Guo wrote:
> > From: Tomasz Nowicki <tomasz.nowicki@linaro.org>
> > 
> > ACPI kernel uses MADT table for proper GIC initialization. It needs to
> > parse GIC related subtables, collect CPU interface and distributor
> > addresses and call driver initialization function (which is hardware
> > abstraction agnostic). In a similar way, FDT initialize GICv1/2.
> > 
> > NOTE: This commit allow to initialize GICv1/2 basic functionality.
> > While now simple GICv2 init call is used, any further GIC features
> > require generic infrastructure for proper ACPI irqchip initialization.
> > That mechanism and stacked irqdomains to support GICv2 MSI/virtualization
> > extension, GICv3/4 and its ITS are considered as next steps.
> > 
> > CC: Jason Cooper <jason@lakedaemon.net>
> > CC: Marc Zyngier <marc.zyngier@arm.com>
> > CC: Thomas Gleixner <tglx@linutronix.de>
> > Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> > Tested-by: Yijing Wang <wangyijing@huawei.com>
> > Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
> > Tested-by: Jon Masters <jcm@redhat.com>
> > Tested-by: Timur Tabi <timur@codeaurora.org>
> > Tested-by: Robert Richter <rrichter@cavium.com>
> > Acked-by: Robert Richter <rrichter@cavium.com>
> > Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
> > Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> > ---
> >  arch/arm64/include/asm/acpi.h        |   2 +
> >  arch/arm64/kernel/acpi.c             |  25 +++++++++
> >  drivers/irqchip/irq-gic.c            | 102 +++++++++++++++++++++++++++++++++++
> >  drivers/irqchip/irqchip.c            |   3 ++
> >  include/linux/acpi.h                 |  14 +++++
> >  include/linux/irqchip/arm-gic-acpi.h |  29 ++++++++++
> >  6 files changed, 175 insertions(+)
> >  create mode 100644 include/linux/irqchip/arm-gic-acpi.h
> > 
> > diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> > index 9a23369..a720a61 100644
> > --- a/arch/arm64/include/asm/acpi.h
> > +++ b/arch/arm64/include/asm/acpi.h
> > @@ -13,6 +13,8 @@
> >  #define _ASM_ACPI_H
> >  
> >  #include <linux/mm.h>
> > +#include <linux/irqchip/arm-gic-acpi.h>
> > +
> >  #include <asm/cputype.h>
> >  #include <asm/smp_plat.h>
> >  
> > diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> > index 31f080e..af308c3 100644
> > --- a/arch/arm64/kernel/acpi.c
> > +++ b/arch/arm64/kernel/acpi.c
> > @@ -359,3 +359,28 @@ void __init acpi_boot_table_init(void)
> >  		pr_err("Can't find FADT\n");
> >  	}
> >  }
> > +
> > +void __init acpi_gic_init(void)
> > +{
> > +	struct acpi_table_header *table;
> > +	acpi_status status;
> > +	acpi_size tbl_size;
> > +	int err;
> > +
> > +	if (acpi_disabled)
> > +		return;
> > +
> > +	status = acpi_get_table_with_size(ACPI_SIG_MADT, 0, &table, &tbl_size);
> > +	if (ACPI_FAILURE(status)) {
> > +		const char *msg = acpi_format_exception(status);
> > +
> > +		pr_err("Failed to get MADT table, %s\n", msg);
> > +		return;
> > +	}
> > +
> > +	err = gic_v2_acpi_init(table);
> > +	if (err)
> > +		pr_err("Failed to initialize GIC IRQ controller");
> > +
> > +	early_acpi_os_unmap_memory((char *)table, tbl_size);
> > +}
> > diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> > index 4634cf7..929d668 100644
> > --- a/drivers/irqchip/irq-gic.c
> > +++ b/drivers/irqchip/irq-gic.c
> > @@ -33,12 +33,14 @@
> >  #include <linux/of.h>
> >  #include <linux/of_address.h>
> >  #include <linux/of_irq.h>
> > +#include <linux/acpi.h>
> >  #include <linux/irqdomain.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/percpu.h>
> >  #include <linux/slab.h>
> >  #include <linux/irqchip/chained_irq.h>
> >  #include <linux/irqchip/arm-gic.h>
> > +#include <linux/irqchip/arm-gic-acpi.h>
> >  
> >  #include <asm/cputype.h>
> >  #include <asm/irq.h>
> > @@ -1086,3 +1088,103 @@ IRQCHIP_DECLARE(msm_8660_qgic, "qcom,msm-8660-qgic", gic_of_init);
> >  IRQCHIP_DECLARE(msm_qgic2, "qcom,msm-qgic2", gic_of_init);
> >  
> >  #endif
> > +
> > +#ifdef CONFIG_ACPI
> > +static phys_addr_t dist_phy_base, cpu_phy_base __initdata;
> > +
> > +static int __init
> > +gic_acpi_parse_madt_cpu(struct acpi_subtable_header *header,
> > +			const unsigned long end)
> > +{
> > +	struct acpi_madt_generic_interrupt *processor;
> > +	phys_addr_t gic_cpu_base;
> > +	static int cpu_base_assigned;
> > +
> > +	processor = (struct acpi_madt_generic_interrupt *)header;
> > +
> > +	if (BAD_MADT_ENTRY(processor, end))
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * There is no support for non-banked GICv1/2 register in ACPI spec.
> > +	 * All CPU interface addresses have to be the same.
> > +	 */
> > +	gic_cpu_base = processor->base_address;
> > +	if (cpu_base_assigned && gic_cpu_base != cpu_phy_base)
> > +		return -EINVAL;
> > +
> > +	cpu_phy_base = gic_cpu_base;
> > +	cpu_base_assigned = 1;
> > +	return 0;
> > +}
> > +
> > +static int __init
> > +gic_acpi_parse_madt_distributor(struct acpi_subtable_header *header,
> > +				const unsigned long end)
> > +{
> > +	struct acpi_madt_generic_distributor *dist;
> > +
> > +	dist = (struct acpi_madt_generic_distributor *)header;
> > +
> > +	if (BAD_MADT_ENTRY(dist, end))
> > +		return -EINVAL;
> > +
> > +	dist_phy_base = dist->base_address;
> > +	return 0;
> > +}
> > +
> > +int __init
> > +gic_v2_acpi_init(struct acpi_table_header *table)
> > +{
> > +	void __iomem *cpu_base, *dist_base;
> > +	int count;
> > +
> > +	/* Collect CPU base addresses */
> > +	count = acpi_parse_entries(ACPI_SIG_MADT,
> > +				   sizeof(struct acpi_table_madt),
> > +				   gic_acpi_parse_madt_cpu, table,
> > +				   ACPI_MADT_TYPE_GENERIC_INTERRUPT, 0);
> > +	if (count <= 0) {
> > +		pr_err("No valid GICC entries exist\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	/*
> > +	 * Find distributor base address. We expect one distributor entry since
> > +	 * ACPI 5.1 spec neither support multi-GIC instances nor GIC cascade.
> > +	 */
> > +	count = acpi_parse_entries(ACPI_SIG_MADT,
> > +				   sizeof(struct acpi_table_madt),
> > +				   gic_acpi_parse_madt_distributor, table,
> > +				   ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR, 0);
> > +	if (count <= 0) {
> > +		pr_err("No valid GICD entries exist\n");
> > +		return -EINVAL;
> > +	} else if (count > 1) {
> > +		pr_err("More than one GICD entry detected\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	cpu_base = ioremap(cpu_phy_base, ACPI_GIC_CPU_IF_MEM_SIZE);
> > +	if (!cpu_base) {
> > +		pr_err("Unable to map GICC registers\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	dist_base = ioremap(dist_phy_base, ACPI_GICV2_DIST_MEM_SIZE);
> > +	if (!dist_base) {
> > +		pr_err("Unable to map GICD registers\n");
> > +		iounmap(cpu_base);
> > +		return -ENOMEM;
> > +	}
> > +
> > +	/*
> > +	 * 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()).
> > +	 */
> > +	gic_init_bases(0, -1, dist_base, cpu_base, 0, NULL);
> > +	irq_set_default_host(gic_data[0].domain);
> > +	return 0;
> > +}
> > +#endif
> > diff --git a/drivers/irqchip/irqchip.c b/drivers/irqchip/irqchip.c
> > index 0fe2f71..5855240 100644
> > --- a/drivers/irqchip/irqchip.c
> > +++ b/drivers/irqchip/irqchip.c
> > @@ -8,6 +8,7 @@
> >   * warranty of any kind, whether express or implied.
> >   */
> >  
> > +#include <linux/acpi.h>
> >  #include <linux/init.h>
> >  #include <linux/of_irq.h>
> >  #include <linux/irqchip.h>
> > @@ -26,4 +27,6 @@ extern struct of_device_id __irqchip_of_table[];
> >  void __init irqchip_init(void)
> >  {
> >  	of_irq_init(__irqchip_of_table);
> > +
> > +	acpi_irq_init();
> >  }
> > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> > index c03d8d1..e27117a 100644
> > --- a/include/linux/acpi.h
> > +++ b/include/linux/acpi.h
> > @@ -557,6 +557,20 @@ static inline int acpi_device_modalias(struct device *dev,
> >  
> >  #endif	/* !CONFIG_ACPI */
> >  
> > +#if defined(CONFIG_ACPI) && defined(CONFIG_ARM64)
> > +static inline void acpi_irq_init(void)
> > +{
> > +	/*
> > +	 * Hardcode ACPI IRQ chip initialization to GICv2 for now.
> > +	 * Proper irqchip infrastructure will be implemented along with
> > +	 * incoming  GICv2m|GICv3|ITS bits.
> > +	 */
> > +	acpi_gic_init();
> > +}
> > +#else
> > +static inline void acpi_irq_init(void) { }
> > +#endif
> 
> I don't want this in a common header.

I don't like it either. What about adding it to a new header,
linux/acpi_irq.h just for the dummy acpi_irq_init()? This would be
similar to the DT equivalent, of_irq_init() in linux/of_irq.h and at
some point it will gain more macros for declaring interrupt controllers
in the ACPI context.

What we objected to previously was calling acpi_gic_init() directly from
the core irqchip_init() and asked for something similar to the more
generic of_irq_init(). The arm64-specific patch above is clearly a
temporary hack until full support for multiple interrupt controllers is
added (we asked for this several times in the past, but the ARM ACPI
guys thought it's too much hassle ;). I don't fully get it since one of
the platforms they target needs GICv2m support anyway).

Anyway, if we are to keep the temporary hack, I think we could define
something like below (possibly in a new linux/acpi_irq.h which includes
asm/irq.h):

#ifndef acpi_irq_init
static inline void acpi_irq_init(void)
{
}
#endif

And in the arm64 asm/irq.h:

static inline void acpi_irq_init(void)
{
	/*
	 * Hardcode ACPI IRQ chip initialization to GICv2 for now.
	 * Proper irqchip infrastructure will be implemented along with
	 * incoming  GICv2m|GICv3|ITS bits.
	 */
	acpi_gic_init();
}
#define acpi_irq_init acpi_irq_init

When the new infrastructure is in place, we can get rid of the #ifndef
and arm64-specific acpi_irq_init().

-- 
Catalin