Subject: [PATCH 01/18] arm64: initial support for GICv3

From: [email-masked] (Christoffer Dall)
Date: Sun, 16 Feb 2014 17:19:25 -0800

On Wed, Feb 05, 2014 at 01:30:33PM +0000, Marc Zyngier wrote:
> The Generic Interrupt Controller (version 3) offers services that are
> similar to GICv2, with a number of additional features:
> - Affinity routing based on the CPU MPIDR (ARE)
> - System register for the CPU interfaces (SRE)
> - Support for more that 8 CPUs
> - Locality-specific Peripheral Interrupts (LPIs)
> - Interrupt Translation Services (ITS)
> 
> This patch adds preliminary support for GICv3 with ARE and SRE,
> non-secure mode only. It relies on higher exception levels to grant ARE
> and SRE access.
> 
> Support for LPI and ITS will be added at a later time.
> 
> Acked-by: Catalin Marinas <[email-masked]>
> Signed-off-by: Marc Zyngier <[email-masked]>
> ---
>  arch/arm64/Kconfig                 |   1 +
>  arch/arm64/kernel/head.S           |  14 +
>  arch/arm64/kernel/hyp-stub.S       |  41 ++-
>  drivers/irqchip/Kconfig            |   5 +
>  drivers/irqchip/Makefile           |   1 +
>  drivers/irqchip/irq-gic-v3.c       | 665 +++++++++++++++++++++++++++++++++++++
>  include/linux/irqchip/arm-gic-v3.h | 190 +++++++++++
>  7 files changed, 915 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/irqchip/irq-gic-v3.c
>  create mode 100644 include/linux/irqchip/arm-gic-v3.h
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index dd4327f..3a7e26d 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -9,6 +9,7 @@ config ARM64
>  	select ARM_AMBA
>  	select ARM_ARCH_TIMER
>  	select ARM_GIC
> +	select ARM_GIC_V3
>  	select BUILDTIME_EXTABLE_SORT
>  	select CLONE_BACKWARDS
>  	select COMMON_CLK
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 0b281ff..522649b 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -22,6 +22,7 @@
>  
>  #include <linux/linkage.h>
>  #include <linux/init.h>
> +#include <linux/irqchip/arm-gic-v3.h>
>  
>  #include <asm/assembler.h>
>  #include <asm/ptrace.h>
> @@ -183,6 +184,19 @@ CPU_LE(	bic	x0, x0, #(3 << 24)	)	// Clear the EE and E0E bits for EL1
>  	msr	cnthctl_el2, x0
>  	msr	cntvoff_el2, xzr		// Clear virtual offset
>  
> +	/* GICv3 system register access */
> +	mrs	x0, id_aa64pfr0_el1
> +	ubfx	x0, x0, #24, #4
> +	cmp	x0, #1
> +	b.ne	3f
> +
> +	mrs	x0, ICC_SRE_EL2			// Set ICC_SRE_EL2.SRE==1
> +	orr	x0, x0, #1
> +	msr	ICC_SRE_EL2, x0
> +	isb					// Make sure SRE is now 1
> +	msr	ICH_HCR_EL2, xzr		// Reset ICC_HCR_EL2 to defaults

Why do we not just set ICC_SRE_EL2.Enable here, but instead do the whole
exception dance below?

> +
> +3:
>  	/* Populate ID registers. */
>  	mrs	x0, midr_el1
>  	mrs	x1, mpidr_el1
> diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
> index 0959611..c850d1e 100644
> --- a/arch/arm64/kernel/hyp-stub.S
> +++ b/arch/arm64/kernel/hyp-stub.S
> @@ -19,6 +19,7 @@
>  
>  #include <linux/init.h>
>  #include <linux/linkage.h>
> +#include <linux/irqchip/arm-gic-v3.h>
>  
>  #include <asm/assembler.h>
>  #include <asm/ptrace.h>
> @@ -51,16 +52,52 @@ ENDPROC(__hyp_stub_vectors)
>  
>  	.align 11
>  
> +#define sysreg_to_iss(op0, op1, crn, crm, op2)	\
> +	(((op0 & 3) << 20) | ((op2 & 7 ) << 17) | \
> +	 ((op1 & 7 ) << 14) | ((crn & 15) << 10) | \
> +	 ((crm & 15) << 1))
> +
>  el1_sync:
> +	// Hack alert: we don't have a stack, and we can't use the one
> +	// from EL1 because our MMU is off. Thankfully, we have
> +	// tpidr_el2, which is under our complete control, and
> +	// tpidr_el0, which can be used as long as we haven't reached
> +	// userspace. Oh hum...

Hmmm.  I feel like either we should tone down the hack alert claim,
because this is after all safe and we just explain what's going on, or
we should just allocate a small stack space following el1_sync and set
the SP upon entry to this handler?

Hopefully none of the code that will ever call into the sysregs trap
ever makes the same assumption that user space is not called yet ;)

> +	msr	tpidr_el2, x1			// Preserve x1
> +
>  	mrs	x1, esr_el2
>  	lsr	x1, x1, #26
>  	cmp	x1, #0x16
> -	b.ne	2f				// Not an HVC trap
> +	b.ne	3f				// Not an HVC trap
> +
> +	// Handle getting/setting vbar_el2
>  	cbz	x0, 1f
>  	msr	vbar_el2, x0			// Set vbar_el2
>  	b	2f
>  1:	mrs	x0, vbar_el2			// Return vbar_el2
> -2:	eret
> +2:	mrs	x1, tpidr_el2			// Restore x1
> +	eret
> +
> +3:	cmp	x1, #0x18			// MSR/MRS?
> +	b.ne	2b
> +
> +	// Handle trapped sys reg access
> +	msr	tpidr_el0, x0			// Preserve x0
> +	mrs	x1, esr_el2
> +	ldr	x0, =sysreg_to_iss(3, 7, 15, 15, 7)
> +	and	x1, x1, x0
> +	ldr	x0, =sysreg_to_iss(3, 0, 12, 12, 5)
> +	eor	x0, x0, x1			// Check for ICC_SRE_EL1
> +	cbnz	x0, 4f				// Something bad happened

Shouldn't we try to do something here, like go to panic on the
exception return here, or not worth it?

> +
> +	// Set ICC_SRE_EL1 access enable
> +	mrs	x1, ICC_SRE_EL2
> +	orr	x1, x1, #(1 << 3)
> +	msr	ICC_SRE_EL2, x1
> +
> +4:	mrs	x0, tpidr_el0			// Restore x0
> +	mrs	x1, tpidr_el2			// Restore x1
> +	eret
>  ENDPROC(el1_sync)
>  
>  .macro invalid_vector	label
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 61ffdca..5b55c46 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -10,6 +10,11 @@ config ARM_GIC
>  config GIC_NON_BANKED
>  	bool
>  
> +config ARM_GIC_V3
> +	bool
> +	select IRQ_DOMAIN
> +	select MULTI_IRQ_HANDLER
> +
>  config ARM_NVIC
>  	bool
>  	select IRQ_DOMAIN
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 86b484c..e6ac9fd 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_ORION_IRQCHIP)		+= irq-orion.o
>  obj-$(CONFIG_ARCH_SUNXI)		+= irq-sun4i.o
>  obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o
>  obj-$(CONFIG_ARM_GIC)			+= irq-gic.o
> +obj-$(CONFIG_ARM_GIC_V3)		+= irq-gic-v3.o
>  obj-$(CONFIG_ARM_NVIC)			+= irq-nvic.o
>  obj-$(CONFIG_ARM_VIC)			+= irq-vic.o
>  obj-$(CONFIG_IMGPDC_IRQ)		+= irq-imgpdc.o
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> new file mode 100644
> index 0000000..487e061
> --- /dev/null
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -0,0 +1,665 @@
> +/*
> + * Copyright (C) 2013 ARM Limited, All Rights Reserved.
> + * Author: Marc Zyngier <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/cpu.h>
> +#include <linux/interrupt.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/percpu.h>
> +#include <linux/slab.h>
> +
> +#include <linux/irqchip/arm-gic-v3.h>
> +
> +#include <asm/cputype.h>
> +#include <asm/exception.h>
> +#include <asm/smp_plat.h>
> +
> +#include "irqchip.h"
> +
> +struct gic_chip_data {
> +	void __iomem		*dist_base;
> +	void __iomem		**redist_base;
> +	void __percpu __iomem	**rdist;
> +	struct irq_domain	*domain;
> +	u64			redist_stride;
> +	u32			redist_regions;
> +	unsigned int		irq_nr;
> +};
> +
> +static struct gic_chip_data gic_data __read_mostly;
> +
> +#define gic_data_rdist_rd_base()	(*__this_cpu_ptr(gic_data.rdist))
> +#define gic_data_rdist_sgi_base()	(gic_data_rdist_rd_base() + SZ_64K)
> +
> +static DEFINE_RAW_SPINLOCK(dist_lock);
> +
> +#define DEFAULT_PMR_VALUE	0xf0
> +
> +static inline void __iomem *gic_dist_base(struct irq_data *d)
> +{
> +	if (d->hwirq < 32)	/* SGI+PPI -> SGI_base for this CPU */
> +		return gic_data_rdist_sgi_base();
> +
> +	if (d->hwirq <= 1023)	/* SPI -> dist_base */
> +		return gic_data.dist_base;
> +
> +	if (d->hwirq >= 8192)
> +		BUG();		/* LPI Detected!!! */
> +
> +	return NULL;
> +}
> +
> +static inline unsigned int gic_irq(struct irq_data *d)
> +{
> +	return d->hwirq;
> +}
> +
> +static void gic_do_wait_for_rwp(void __iomem *base)
> +{
> +	u32 val;
> +
> +	do {
> +		val = readl_relaxed(base + GICD_CTLR);
> +		cpu_relax();
> +	} while (val & GICD_CTLR_RWP);
> +}
> +
> +/* Wait for completion of a distributor change */
> +static void gic_dist_wait_for_rwp(void)
> +{
> +	gic_do_wait_for_rwp(gic_data.dist_base);
> +}
> +
> +/* Wait for completion of a redistributor change */
> +static void gic_redist_wait_for_rwp(void)
> +{
> +	gic_do_wait_for_rwp(gic_data_rdist_rd_base());
> +}
> +
> +static void gic_wait_for_rwp(int irq)
> +{
> +	if (irq < 32)
> +		gic_redist_wait_for_rwp();
> +	else
> +		gic_dist_wait_for_rwp();
> +}
> +
> +/* Low level accessors */
> +static u64 gic_read_iar(void)
> +{
> +	u64 irqstat;
> +
> +	asm volatile("mrs %0, " reg(ICC_IAR1_EL1) : "=r" (irqstat));
> +	return irqstat;
> +}
> +
> +static void gic_write_pmr(u64 val)
> +{
> +	asm volatile("msr " reg(ICC_PMR_EL1) ", %0" : : "r" (val));
> +	isb();
> +}
> +
> +static void gic_write_ctlr(u64 val)
> +{
> +	asm volatile("msr " reg(ICC_CTLR_EL1) ", %0" : : "r" (val));
> +	isb();
> +}
> +
> +static void gic_write_grpen1(u64 val)
> +{
> +	asm volatile("msr " reg(ICC_GRPEN1_EL1) ", %0" : : "r" (val));
> +	isb();
> +}
> +
> +static void gic_write_sgi1r(u64 val)
> +{
> +	asm volatile("msr " reg(ICC_SGI1R_EL1) ", %0" : : "r" (val));
> +	isb();
> +}
> +
> +static void gic_enable_sre(void)
> +{
> +	u64 val;
> +
> +	/* This access is likely to trap into EL2 */
> +	asm volatile("mrs %0, " reg(ICC_SRE_EL1) : "=r" (val));
> +	val |= GICC_SRE_EL1_SRE;
> +	asm volatile("msr " reg(ICC_SRE_EL1) ", %0" : : "r" (val));
> +	isb();
> +}
> +
> +static void gic_enable_redist(void)
> +{
> +	void __iomem *rbase;
> +	u32 val;
> +
> +	rbase = gic_data_rdist_rd_base();
> +
> +	/* Wake up this CPU redistributor */
> +	val = readl_relaxed(rbase + GICR_WAKER);
> +	val &= ~GICR_WAKER_ProcessorSleep;
> +	writel_relaxed(val, rbase + GICR_WAKER);
> +
> +	do {
> +		val = readl_relaxed(rbase + GICR_WAKER);
> +		cpu_relax();
> +	} while (val & GICR_WAKER_ChildrenAsleep);
> +}
> +
> +/*
> + * Routines to acknowledge, disable and enable interrupts
> + */
> +static void gic_mask_irq(struct irq_data *d)
> +{
> +	u32 mask = 1 << (gic_irq(d) % 32);
> +
> +	raw_spin_lock(&dist_lock);
> +	writel_relaxed(mask, gic_dist_base(d) + GICD_ICENABLER + (gic_irq(d) / 32) * 4);
> +	gic_wait_for_rwp(gic_irq(d));
> +	raw_spin_unlock(&dist_lock);
> +}
> +
> +static void gic_unmask_irq(struct irq_data *d)
> +{
> +	u32 mask = 1 << (gic_irq(d) % 32);
> +
> +	raw_spin_lock(&dist_lock);
> +	writel_relaxed(mask, gic_dist_base(d) + GICD_ISENABLER + (gic_irq(d) / 32) * 4);
> +	gic_wait_for_rwp(gic_irq(d));
> +	raw_spin_unlock(&dist_lock);
> +}
> +
> +static void gic_eoi_irq(struct irq_data *d)
> +{
> +	gic_write_eoir(gic_irq(d));
> +}
> +
> +static int gic_set_type(struct irq_data *d, unsigned int type)
> +{
> +	void __iomem *base = gic_dist_base(d);
> +	unsigned int irq = gic_irq(d);
> +	u32 enablemask = 1 << (irq % 32);
> +	u32 enableoff = (irq / 32) * 4;
> +	u32 confmask = 0x2 << ((irq % 16) * 2);
> +	u32 confoff = (irq / 16) * 4;
> +	bool enabled = false;
> +	u32 val;
> +
> +	/* Interrupt configuration for SGIs can't be changed */
> +	if (irq < 16)
> +		return -EINVAL;
> +
> +	if (type != IRQ_TYPE_LEVEL_HIGH && type != IRQ_TYPE_EDGE_RISING)
> +		return -EINVAL;
> +
> +	raw_spin_lock(&dist_lock);
> +
> +	val = readl_relaxed(base + GICD_ICFGR + confoff);
> +	if (type == IRQ_TYPE_LEVEL_HIGH)
> +		val &= ~confmask;
> +	else if (type == IRQ_TYPE_EDGE_RISING)
> +		val |= confmask;
> +
> +	/*
> +	 * As recommended by the spec, disable the interrupt before changing
> +	 * the configuration
> +	 */
> +	if (readl_relaxed(base + GICD_ISENABLER + enableoff) & enablemask) {
> +		writel_relaxed(enablemask, base + GICD_ICENABLER + enableoff);
> +		gic_wait_for_rwp(irq);
> +		enabled = true;
> +	}
> +
> +	writel_relaxed(val, base + GICD_ICFGR + confoff);
> +
> +	if (enabled) {
> +		writel_relaxed(enablemask, base + GICD_ISENABLER + enableoff);
> +		gic_wait_for_rwp(irq);
> +	}
> +
> +	raw_spin_unlock(&dist_lock);
> +
> +	return 0;
> +}
> +
> +static int gic_retrigger(struct irq_data *d)
> +{
> +	return -ENXIO;
> +}
> +
> +static u64 gic_mpidr_to_affinity(u64 mpidr)
> +{
> +	/* Make sure we don't broadcast the interrupt */
> +	return mpidr & ~GICD_IROUTER_SPI_MODE_ANY;
> +}
> +
> +static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
> +{
> +	u64 irqnr;
> +
> +	do {
> +		irqnr = gic_read_iar();
> +
> +		if (likely(irqnr > 15 && irqnr < 1021)) {
> +			irqnr = irq_find_mapping(gic_data.domain, irqnr);
> +			handle_IRQ(irqnr, regs);
> +			continue;
> +		}
> +		if (irqnr < 16) {
> +			gic_write_eoir(irqnr);
> +#ifdef CONFIG_SMP
> +			handle_IPI(irqnr, regs);
> +#else
> +			WARN_ONCE(true, "Unexpected SGI received!\n");
> +#endif
> +			continue;
> +		}
> +	} while (irqnr != 0x3ff);
> +}
> +
> +static void __init gic_dist_init(void)
> +{
> +	unsigned int i;
> +	u64 affinity;
> +	int gic_irqs = gic_data.irq_nr;
> +	void __iomem *base = gic_data.dist_base;
> +
> +	/* Disable the distributor */
> +	writel_relaxed(0, base + GICD_CTLR);
> +
> +	/*
> +	 * Set all global interrupts to be level triggered, active low.
> +	 */
> +	for (i = 32; i < gic_data.irq_nr; i += 16)
> +		writel_relaxed(0, base + GICD_ICFGR + i / 4);
> +
> +	/*
> +	 * Set priority on all global interrupts.
> +	 */
> +	for (i = 32; i < gic_irqs; i += 4)
> +		writel_relaxed(0xa0a0a0a0, base + GICD_IPRIORITYR + i);
> +
> +	/*
> +	 * Disable all interrupts.  Leave the PPI and SGIs alone
> +	 * as these enables are banked registers.

as these are enabled through banked registers?

also, should banked registers be redistributor registers?

> +	 */
> +	for (i = 32; i < gic_irqs; i += 32)
> +		writel_relaxed(0xffffffff, base + GICD_ICENABLER + i / 8);
> +
> +	gic_dist_wait_for_rwp();
> +
> +	writel_relaxed(GICD_CTLR_ARE_NS | GICD_CTLR_ENABLE_G1A | GICD_CTLR_ENABLE_G1,
> +		       base + GICD_CTLR);

why set GICD_CTLR_ENABLE_G1 ?

> +
> +	/*
> +	 * Set all global interrupts to the boot CPU only. ARE must be
> +	 * enabled.
> +	 */
> +	affinity = gic_mpidr_to_affinity(read_cpuid_mpidr());
> +	for (i = 32; i < gic_data.irq_nr; i++)
> +		writeq_relaxed(affinity, base + GICD_IROUTER + i * 8);
> +}
> +
> +static int __init gic_populate_rdist(void)
> +{
> +	u64 mpidr = cpu_logical_map(smp_processor_id());
> +	u64 typer;
> +	u64 aff;
> +	int i;
> +
> +	aff  = mpidr & ((1 << 24) - 1);
> +	aff |= (mpidr >> 8) & (0xffUL << 24);

Some defines would be nice for this if it makes sense in any way.

> +
> +	for (i = 0; i < gic_data.redist_regions; i++) {
> +		void __iomem *ptr = gic_data.redist_base[i];
> +		u32 reg;
> +
> +		reg = readl_relaxed(ptr + GICR_PIDR2) & GIC_PIDR2_ARCH_MASK;
> +		if (reg != 0x30 && reg != 0x40) { /* We're in trouble... */
> +			pr_warn("No redistributor present @%p\n", ptr);
> +			break;
> +		}
> +
> +		do {
> +			typer = readq_relaxed(ptr + GICR_TYPER);
> +			if ((typer >> 32) == aff) {
> +				gic_data_rdist_rd_base() = ptr;
> +				pr_info("CPU%d: found redistributor %llx @%p\n",
> +					smp_processor_id(),
> +					(unsigned long long) mpidr, ptr);
> +				return 0;
> +			}
> +
> +			if (gic_data.redist_stride) {
> +				ptr += gic_data.redist_stride;
> +			} else {
> +				ptr += SZ_64K * 2; /* Skip RD_base + SGI_base */
> +				if (typer & GICR_TYPER_VLPIS)
> +					ptr += SZ_64K * 2; /* Skip VLPI_base + reserved page */
> +			}
> +		} while (!(typer & GICR_TYPER_LAST));
> +	}
> +
> +	/* We couldn't even deal with ourselves... */
> +	WARN(true, "CPU%d: mpidr %lx has no re-distributor!\n",
> +	     smp_processor_id(), (unsigned long)mpidr);
> +	return -ENODEV;
> +}
> +
> +static void __init gic_cpu_init(void)
> +{
> +	void __iomem *rbase;
> +	int i;
> +
> +	/* Register ourselves with the rest of the world */
> +	if (gic_populate_rdist())
> +		return;
> +
> +	gic_enable_redist();
> +
> +	rbase = gic_data_rdist_sgi_base();
> +
> +	/*
> +	 * Set priority on PPI and SGI interrupts
> +	 */
> +	for (i = 0; i < 32; i += 4)
> +		writel_relaxed(0xa0a0a0a0, rbase + GICR_IPRIORITYR0 + i * 4 / 4);

(i * 4) / 4 == i, last I checked.

> +
> +	/*
> +	 * Disable all PPI interrupts, ensure all SGI interrupts are
> +	 * enabled.

Why do we disable all PPIs?

> +	 */
> +	writel_relaxed(0xffff0000, rbase + GICR_ICENABLER0);
> +	writel_relaxed(0x0000ffff, rbase + GICR_ISENABLER0);
> +
> +	gic_redist_wait_for_rwp();
> +
> +	/* Enable system registers */
> +	gic_enable_sre();
> +
> +	/* Set priority mask register */
> +	gic_write_pmr(DEFAULT_PMR_VALUE);
> +
> +	/* EOI drops priority too (mode 0) */

you mean deactives the interrupt too, right? It always performs a
priority drop doesn't it?

> +	gic_write_ctlr(GICC_CTLR_EL1_EOImode_drop_dir);
> +
> +	/* ... and let's hit the road... */
> +	gic_write_grpen1(1);
> +}
> +
> +#ifdef CONFIG_SMP
> +static int __init gic_secondary_init(struct notifier_block *nfb,
> +				     unsigned long action, void *hcpu)
> +{
> +	if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
> +		gic_cpu_init();
> +	return NOTIFY_OK;
> +}
> +
> +/*
> + * Notifier for enabling the GIC CPU interface. Set an arbitrarily high
> + * priority because the GIC needs to be up before the ARM generic timers.

I actually don't understand this bit, but it also sits in the original
code, so I assume it's correct.

> + */
> +static struct notifier_block __initdata gic_cpu_notifier = {
> +	.notifier_call = gic_secondary_init,
> +	.priority = 100,
> +};
> +
> +static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
> +				   u64 cluster_id)
> +{
> +	int cpu = *base_cpu;
> +	u64 mpidr = cpu_logical_map(cpu);
> +	u16 tlist = 0;
> +
> +	while (cpu < nr_cpu_ids) {
> +		/*
> +		 * If we ever get a cluster of more than 16 CPUs, just
> +		 * scream and skip that CPU.
> +		 */
> +		if (WARN_ON((mpidr & 0xff) >= 16))
> +			goto out;
> +
> +		tlist |= 1 << (mpidr & 0xf);
> +
> +		cpu = cpumask_next(cpu, mask);
> +		mpidr = cpu_logical_map(cpu);

Are you not accessing memory beyond the __cpu_logical_map array here
when the cpu is the last one at the beginning of the loop?

> +
> +		if (cluster_id != (mpidr & ~0xffUL)) {
> +			cpu--;
> +			goto out;
> +		}
> +	}
> +out:
> +	*base_cpu = cpu;
> +	return tlist;
> +}
> +
> +static void gic_send_sgi(u64 cluster_id, u16 tlist, unsigned int irq)
> +{
> +	u64 val;
> +
> +	val  = (cluster_id & 0xff00ff0000UL) << 16; /* Aff3 + Aff2 */
> +	val |= (cluster_id & 0xff00) << 8;	    /* Aff1 */
> +	val |= irq << 24;
> +	val |= tlist;
> +
> +	pr_debug("CPU%d: ICC_SGI1R_EL1 %llx\n", smp_processor_id(), val);
> +	gic_write_sgi1r(val);
> +}
> +
> +static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
> +{
> +	int cpu;
> +
> +	if (WARN_ON(irq >= 16))
> +		return;
> +
> +	/*
> +	 * Ensure that stores to Normal memory are visible to the
> +	 * other CPUs before issuing the IPI.
> +	 */
> +	dsb();
> +
> +	for_each_cpu_mask(cpu, *mask) {
> +		u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> +		u16 tlist;
> +
> +		tlist = gic_compute_target_list(&cpu, mask, cluster_id);

I think it would be potentially slightly prettier if this function
returned the last cpu in the cluster so the loop iterator mangling was
kept local to this function and took a pointer to the tlist it was to
fill instead, but, this is a minor detail.

> +		gic_send_sgi(cluster_id, tlist, irq);
> +	}
> +}
> +
> +static void gic_smp_init(void)
> +{
> +	set_smp_cross_call(gic_raise_softirq);
> +	register_cpu_notifier(&gic_cpu_notifier);
> +}
> +
> +static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
> +			    bool force)
> +{
> +	unsigned int cpu = cpumask_any_and(mask_val, cpu_online_mask);
> +	void __iomem *reg;
> +	u64 val;
> +
> +	if (gic_irq(d) < 32)
> +		return -EINVAL;
> +
> +	reg = gic_dist_base(d) + GICD_IROUTER + (gic_irq(d) * 8);
> +	val = gic_mpidr_to_affinity(cpu_logical_map(cpu));
> +
> +	writeq_relaxed(val, reg);
> +
> +	return IRQ_SET_MASK_OK;
> +}
> +#else
> +#define gic_set_affinity	NULL
> +#define gic_smp_init()		do { } while(0)
> +#endif
> +
> +static struct irq_chip gic_chip = {
> +	.name			= "GICv3",
> +	.irq_mask		= gic_mask_irq,
> +	.irq_unmask		= gic_unmask_irq,
> +	.irq_eoi		= gic_eoi_irq,
> +	.irq_set_type		= gic_set_type,
> +	.irq_retrigger		= gic_retrigger,
> +	.irq_set_affinity	= gic_set_affinity,
> +};
> +
> +static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
> +				irq_hw_number_t hw)
> +{
> +	if (hw < 32) {
> +		irq_set_percpu_devid(irq);
> +		irq_set_chip_and_handler(irq, &gic_chip,
> +					 handle_percpu_devid_irq);
> +		set_irq_flags(irq, IRQF_VALID | IRQF_NOAUTOEN);
> +	} else {
> +		irq_set_chip_and_handler(irq, &gic_chip,
> +					 handle_fasteoi_irq);
> +		set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);

will this ever be compiled for arch/arm?  If not, does it make sense to
keep the set_irq_flags calls?

> +	}
> +	irq_set_chip_data(irq, d->host_data);
> +	return 0;
> +}
> +
> +static int gic_irq_domain_xlate(struct irq_domain *d,
> +				struct device_node *controller,
> +				const u32 *intspec, unsigned int intsize,
> +				unsigned long *out_hwirq, unsigned int *out_type)
> +{
> +	if (d->of_node != controller)
> +		return -EINVAL;
> +	if (intsize < 3)
> +		return -EINVAL;
> +
> +	switch(intspec[0]) {
> +	case 0:			/* SPI */
> +		*out_hwirq = intspec[1] + 32;
> +		break;
> +	case 1:			/* PPI */
> +		*out_hwirq = intspec[1] + 16;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	*out_type = intspec[2] & IRQ_TYPE_SENSE_MASK;
> +	return 0;
> +}
> +
> +static const struct irq_domain_ops gic_irq_domain_ops = {
> +	.map = gic_irq_domain_map,
> +	.xlate = gic_irq_domain_xlate,
> +};
> +
> +static int __init gic_of_init(struct device_node *node, struct device_node *parent)
> +{
> +	void __iomem *dist_base;
> +	void __iomem **redist_base;
> +	u64 redist_stride;
> +	u32 redist_regions;
> +	u32 reg;
> +	int gic_irqs;
> +	int err;
> +	int i;
> +
> +	dist_base = of_iomap(node, 0);
> +	if (!dist_base) {
> +		pr_warn("%s: unable to map gic dist registers\n",
> +			node->full_name);

shouldn't these be pr_err?

> +		return -ENXIO;
> +	}
> +
> +	reg = readl_relaxed(dist_base + GICD_PIDR2) & GIC_PIDR2_ARCH_MASK;
> +	if (reg != 0x30 && reg != 0x40) {

Is everything we do going to work with a GICv4? Anything else we need to
initialize if it's a GICv4?

> +		pr_warn("%s: no distributor detected, giving up\n",
> +			node->full_name);
> +		err = -ENODEV;
> +		goto out_unmap_dist;
> +	}
> +
> +	if (of_property_read_u32(node, "#redistributor-regions", &redist_regions))
> +		redist_regions = 1;
> +
> +	redist_base = kzalloc(sizeof(*redist_base) * redist_regions, GFP_KERNEL);
> +	if (!redist_base) {
> +		err = -ENOMEM;
> +		goto out_unmap_dist;
> +	}
> +
> +	for (i = 0; i < redist_regions; i++) {
> +		redist_base[i] = of_iomap(node, 1 + i);
> +		if (!redist_base[i]) {
> +			pr_warn("%s: couldn't map region %d\n",
> +				node->full_name, i);
> +			err = -ENODEV;
> +			goto out_unmap_rdist;
> +		}
> +	}
> +
> +	if (of_property_read_u64(node, "redistributor-stride", &redist_stride))
> +		redist_stride = 0;

The binding doesn't specify this as a two-cell property, so I assume
this won't work if you follow the example in the bindings doc.

> +
> +	gic_data.dist_base = dist_base;
> +	gic_data.redist_base = redist_base;
> +	gic_data.redist_regions = redist_regions;
> +	gic_data.redist_stride = redist_stride;
> +
> +	/*
> +	 * Find out how many interrupts are supported.
> +	 * The GIC only supports up to 1020 interrupt sources (SGI+PPI+SPI)
> +	 */
> +	gic_irqs = readl_relaxed(gic_data.dist_base + GICD_TYPER) & 0x1f;
> +	gic_irqs = (gic_irqs + 1) * 32;
> +	if (gic_irqs > 1020)
> +		gic_irqs = 1020;
> +	gic_data.irq_nr = gic_irqs;
> +
> +	gic_data.domain = irq_domain_add_linear(node, gic_irqs - 16,
> +						&gic_irq_domain_ops, &gic_data);
> +	gic_data.rdist = alloc_percpu(typeof(*gic_data.rdist));
> +
> +	if (WARN_ON(!gic_data.domain) || WARN_ON(!gic_data.rdist)) {
> +		err = -ENOMEM;
> +		goto out_free;
> +	}
> +
> +	set_handle_irq(gic_handle_irq);
> +
> +	gic_smp_init();
> +	gic_dist_init();
> +	gic_cpu_init();
> +
> +	return 0;
> +
> +out_free:
> +	free_percpu(gic_data.rdist);
> +out_unmap_rdist:
> +	for (i = 0; i < redist_regions; i++)
> +		if (redist_base[i])
> +			iounmap(redist_base[i]);
> +	kfree(redist_base);
> +out_unmap_dist:
> +	iounmap(dist_base);
> +	return err;
> +}
> +
> +IRQCHIP_DECLARE(gic_v3, "arm,gic-v3", gic_of_init);
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> new file mode 100644
> index 0000000..e4d060a
> --- /dev/null
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -0,0 +1,190 @@
> +/*
> + * Copyright (C) 2013 ARM Limited, All Rights Reserved.
> + * Author: Marc Zyngier <[email-masked]>
> + *
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +#ifndef __LINUX_IRQCHIP_ARM_GIC_V3_H
> +#define __LINUX_IRQCHIP_ARM_GIC_V3_H
> +
> +/*
> + * Distributor registers. We assume we're running non-secure, with ARE
> + * being set. Secure-only and non-ARE registers are not described.
> + */
> +#define GICD_CTLR			0x0000
> +#define GICD_TYPER			0x0004
> +#define GICD_IIDR			0x0008
> +#define GICD_STATUSR			0x0010
> +#define GICD_SETSPI_NSR			0x0040
> +#define GICD_CLRSPI_NSR			0x0048
> +#define GICD_SETSPI_SR			0x0050
> +#define GICD_CLRSPI_SR			0x0058
> +#define GICD_SEIR			0x0068
> +#define GICD_ISENABLER			0x0100
> +#define GICD_ICENABLER			0x0180
> +#define GICD_ISPENDR			0x0200
> +#define GICD_ICPENDR			0x0280
> +#define GICD_ISACTIVER			0x0300
> +#define GICD_ICACTIVER			0x0380
> +#define GICD_IPRIORITYR			0x0400
> +#define GICD_ICFGR			0x0C00
> +#define GICD_IROUTER			0x6000
> +#define GICD_PIDR2			0xFFE8
> +
> +#define GICD_CTLR_RWP			(1U << 31)
> +#define GICD_CTLR_ARE_NS		(1U << 4)
> +#define GICD_CTLR_ENABLE_G1A		(1U << 1)
> +#define GICD_CTLR_ENABLE_G1		(1U << 0)
> +
> +#define GICD_IROUTER_SPI_MODE_ONE	(0U << 31)
> +#define GICD_IROUTER_SPI_MODE_ANY	(1U << 31)
> +
> +#define GIC_PIDR2_ARCH_MASK		0xf0
> +
> +/*
> + * Re-Distributor registers, offsets from RD_base
> + */
> +#define GICR_CTLR			GICD_CTLR
> +#define GICR_IIDR			0x0004
> +#define GICR_TYPER			0x0008
> +#define GICR_STATUSR			GICD_STATUSR
> +#define GICR_WAKER			0x0014
> +#define GICR_SETLPIR			0x0040
> +#define GICR_CLRLPIR			0x0048
> +#define GICR_SEIR			GICD_SEIR
> +#define GICR_PROPBASER			0x0070
> +#define GICR_PENDBASER			0x0078
> +#define GICR_INVLPIR			0x00A0
> +#define GICR_INVALLR			0x00B0
> +#define GICR_SYNCR			0x00C0
> +#define GICR_MOVLPIR			0x0100
> +#define GICR_MOVALLR			0x0110
> +#define GICR_PIDR2			GICD_PIDR2
> +
> +#define GICR_WAKER_ProcessorSleep	(1U << 1)
> +#define GICR_WAKER_ChildrenAsleep	(1U << 2)
> +
> +/*
> + * Re-Distributor registers, offsets from SGI_base
> + */
> +#define GICR_ISENABLER0			GICD_ISENABLER
> +#define GICR_ICENABLER0			GICD_ICENABLER
> +#define GICR_ISPENDR0			GICD_ISPENDR
> +#define GICR_ICPENDR0			GICD_ICPENDR
> +#define GICR_ISACTIVER0			GICD_ISACTIVER
> +#define GICR_ICACTIVER0			GICD_ICACTIVER
> +#define GICR_IPRIORITYR0		GICD_IPRIORITYR
> +#define GICR_ICFGR0			GICD_ICFGR
> +
> +#define GICR_TYPER_VLPIS		(1U << 1)
> +#define GICR_TYPER_LAST			(1U << 4)

nit: why are these TYPER definitions down here when the TYPER register
is defined above and so the WAKER bit definitions?

> +
> +/*
> + * CPU interface registers
> + */
> +#define GICC_CTLR_EL1_EOImode_drop_dir	(0U << 1)
> +#define GICC_CTLR_EL1_EOImode_drop	(1U << 1)
> +#define GICC_SRE_EL1_SRE		(1U << 0)
> +
> +/*
> + * Hypervisor interface registers (SRE only)
> + */
> +#define GICH_LR_VIRTUAL_ID_MASK		((1UL << 32) - 1)
> +
> +#define GICH_LR_EOI			(1UL << 41)
> +#define GICH_LR_GROUP			(1UL << 60)
> +#define GICH_LR_STATE			(3UL << 62)
> +#define GICH_LR_PENDING_BIT		(1UL << 62)
> +#define GICH_LR_ACTIVE_BIT		(1UL << 63)
> +
> +#define GICH_MISR_EOI			(1 << 0)
> +#define GICH_MISR_U			(1 << 1)
> +
> +#define GICH_HCR_EN			(1 << 0)
> +#define GICH_HCR_UIE			(1 << 1)
> +
> +#define GICH_VMCR_CTLR_SHIFT		0
> +#define GICH_VMCR_CTLR_MASK		(0x21f << GICH_VMCR_CTLR_SHIFT)
> +#define GICH_VMCR_BPR1_SHIFT		18
> +#define GICH_VMCR_BPR1_MASK		(7 << GICH_VMCR_BPR1_SHIFT)
> +#define GICH_VMCR_BPR0_SHIFT		21
> +#define GICH_VMCR_BPR0_MASK		(7 << GICH_VMCR_BPR0_SHIFT)
> +#define GICH_VMCR_PMR_SHIFT		24
> +#define GICH_VMCR_PMR_MASK		(0xffUL << GICH_VMCR_PMR_SHIFT)
> +
> +#define ICC_EOIR1_EL1			S3_0_C12_C12_1
> +#define ICC_IAR1_EL1			S3_0_C12_C12_0
> +#define ICC_SGI1R_EL1			S3_0_C12_C11_5
> +#define ICC_PMR_EL1			S3_0_C4_C6_0
> +#define ICC_CTLR_EL1			S3_0_C12_C12_4
> +#define ICC_SRE_EL1			S3_0_C12_C12_5
> +#define ICC_GRPEN1_EL1			S3_0_C12_C12_7
> +
> +#define ICC_SRE_EL2			S3_4_C12_C9_5
> +
> +#define ICH_VSEIR_EL2			S3_4_C12_C9_4
> +#define ICH_HCR_EL2			S3_4_C12_C11_0
> +#define ICH_VTR_EL2			S3_4_C12_C11_1
> +#define ICH_MISR_EL2			S3_4_C12_C11_2
> +#define ICH_EISR_EL2			S3_4_C12_C11_3
> +#define ICH_ELSR_EL2			S3_4_C12_C11_5
> +#define ICH_VMCR_EL2			S3_4_C12_C11_7
> +
> +#define __LR0_EL2(x)			S3_4_C12_C12_ ## x
> +#define __LR8_EL2(x)			S3_4_C12_C13_ ## x
> +
> +#define ICH_LR0_EL2			__LR0_EL2(0)
> +#define ICH_LR1_EL2			__LR0_EL2(1)
> +#define ICH_LR2_EL2			__LR0_EL2(2)
> +#define ICH_LR3_EL2			__LR0_EL2(3)
> +#define ICH_LR4_EL2			__LR0_EL2(4)
> +#define ICH_LR5_EL2			__LR0_EL2(5)
> +#define ICH_LR6_EL2			__LR0_EL2(6)
> +#define ICH_LR7_EL2			__LR0_EL2(7)
> +#define ICH_LR8_EL2			__LR8_EL2(0)
> +#define ICH_LR9_EL2			__LR8_EL2(1)
> +#define ICH_LR10_EL2			__LR8_EL2(2)
> +#define ICH_LR11_EL2			__LR8_EL2(3)
> +#define ICH_LR12_EL2			__LR8_EL2(4)
> +#define ICH_LR13_EL2			__LR8_EL2(5)
> +#define ICH_LR14_EL2			__LR8_EL2(6)
> +#define ICH_LR15_EL2			__LR8_EL2(7)
> +
> +#define __AP0Rx_EL2(x)			S3_4_C12_C8_ ## x
> +#define ICH_AP0R0_EL2			__AP0Rx_EL2(0)
> +#define ICH_AP0R1_EL2			__AP0Rx_EL2(1)
> +#define ICH_AP0R2_EL2			__AP0Rx_EL2(2)
> +#define ICH_AP0R3_EL2			__AP0Rx_EL2(3)
> +
> +#define __AP1Rx_EL2(x)			S3_4_C12_C9_ ## x
> +#define ICH_AP1R0_EL2			__AP1Rx_EL2(0)
> +#define ICH_AP1R1_EL2			__AP1Rx_EL2(1)
> +#define ICH_AP1R2_EL2			__AP1Rx_EL2(2)
> +#define ICH_AP1R3_EL2			__AP1Rx_EL2(3)

That was fun to review.

> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/stringify.h>
> +
> +#define reg(x)		__stringify(x)
> +
> +static inline void gic_write_eoir(u64 irq)
> +{
> +	asm volatile("msr " reg(ICC_EOIR1_EL1) ", %0" : : "r" (irq));
> +	isb();
> +}
> +
> +#endif
> +
> +#endif
> -- 
> 1.8.3.4
>