KVM: arm64: timer: Add support for SW-based deactivation

[mirror_ubuntu-jammy-kernel.git] / drivers / irqchip / irq-apple-aic.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright The Asahi Linux Contributors
 *
 * Based on irq-lpc32xx:
 *   Copyright 2015-2016 Vladimir Zapolskiy <vz@mleia.com>
 * Based on irq-bcm2836:
 *   Copyright 2015 Broadcom
 */

/*
 * AIC is a fairly simple interrupt controller with the following features:
 *
 * - 896 level-triggered hardware IRQs
 *   - Single mask bit per IRQ
 *   - Per-IRQ affinity setting
 *   - Automatic masking on event delivery (auto-ack)
 *   - Software triggering (ORed with hw line)
 * - 2 per-CPU IPIs (meant as "self" and "other", but they are
 *   interchangeable if not symmetric)
 * - Automatic prioritization (single event/ack register per CPU, lower IRQs =
 *   higher priority)
 * - Automatic masking on ack
 * - Default "this CPU" register view and explicit per-CPU views
 *
 * In addition, this driver also handles FIQs, as these are routed to the same
 * IRQ vector. These are used for Fast IPIs (TODO), the ARMv8 timer IRQs, and
 * performance counters (TODO).
 *
 * Implementation notes:
 *
 * - This driver creates two IRQ domains, one for HW IRQs and internal FIQs,
 *   and one for IPIs.
 * - Since Linux needs more than 2 IPIs, we implement a software IRQ controller
 *   and funnel all IPIs into one per-CPU IPI (the second "self" IPI is unused).
 * - FIQ hwirq numbers are assigned after true hwirqs, and are per-cpu.
 * - DT bindings use 3-cell form (like GIC):
 *   - <0 nr flags> - hwirq #nr
 *   - <1 nr flags> - FIQ #nr
 *     - nr=0  Physical HV timer
 *     - nr=1  Virtual HV timer
 *     - nr=2  Physical guest timer
 *     - nr=3  Virtual guest timer
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/bits.h>
#include <linux/bitfield.h>
#include <linux/cpuhotplug.h>
#include <linux/io.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/limits.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <asm/exception.h>
#include <asm/sysreg.h>
#include <asm/virt.h>

#include <dt-bindings/interrupt-controller/apple-aic.h>

/*
 * AIC registers (MMIO)
 */

#define AIC_INFO                0x0004
#define AIC_INFO_NR_HW          GENMASK(15, 0)

#define AIC_CONFIG              0x0010

#define AIC_WHOAMI              0x2000
#define AIC_EVENT               0x2004
#define AIC_EVENT_TYPE          GENMASK(31, 16)
#define AIC_EVENT_NUM           GENMASK(15, 0)

#define AIC_EVENT_TYPE_HW       1
#define AIC_EVENT_TYPE_IPI      4
#define AIC_EVENT_IPI_OTHER     1
#define AIC_EVENT_IPI_SELF      2

#define AIC_IPI_SEND            0x2008
#define AIC_IPI_ACK             0x200c
#define AIC_IPI_MASK_SET        0x2024
#define AIC_IPI_MASK_CLR        0x2028

#define AIC_IPI_SEND_CPU(cpu)   BIT(cpu)

#define AIC_IPI_OTHER           BIT(0)
#define AIC_IPI_SELF            BIT(31)

#define AIC_TARGET_CPU          0x3000
#define AIC_SW_SET              0x4000
#define AIC_SW_CLR              0x4080
#define AIC_MASK_SET            0x4100
#define AIC_MASK_CLR            0x4180

#define AIC_CPU_IPI_SET(cpu)    (0x5008 + ((cpu) << 7))
#define AIC_CPU_IPI_CLR(cpu)    (0x500c + ((cpu) << 7))
#define AIC_CPU_IPI_MASK_SET(cpu) (0x5024 + ((cpu) << 7))
#define AIC_CPU_IPI_MASK_CLR(cpu) (0x5028 + ((cpu) << 7))

#define MASK_REG(x)             (4 * ((x) >> 5))
#define MASK_BIT(x)             BIT((x) & GENMASK(4, 0))

/*
 * IMP-DEF sysregs that control FIQ sources
 * Note: sysreg-based IPIs are not supported yet.
 */

/* Core PMC control register */
#define SYS_IMP_APL_PMCR0_EL1           sys_reg(3, 1, 15, 0, 0)
#define PMCR0_IMODE                     GENMASK(10, 8)
#define PMCR0_IMODE_OFF                 0
#define PMCR0_IMODE_PMI                 1
#define PMCR0_IMODE_AIC                 2
#define PMCR0_IMODE_HALT                3
#define PMCR0_IMODE_FIQ                 4
#define PMCR0_IACT                      BIT(11)

/* IPI request registers */
#define SYS_IMP_APL_IPI_RR_LOCAL_EL1    sys_reg(3, 5, 15, 0, 0)
#define SYS_IMP_APL_IPI_RR_GLOBAL_EL1   sys_reg(3, 5, 15, 0, 1)
#define IPI_RR_CPU                      GENMASK(7, 0)
/* Cluster only used for the GLOBAL register */
#define IPI_RR_CLUSTER                  GENMASK(23, 16)
#define IPI_RR_TYPE                     GENMASK(29, 28)
#define IPI_RR_IMMEDIATE                0
#define IPI_RR_RETRACT                  1
#define IPI_RR_DEFERRED                 2
#define IPI_RR_NOWAKE                   3

/* IPI status register */
#define SYS_IMP_APL_IPI_SR_EL1          sys_reg(3, 5, 15, 1, 1)
#define IPI_SR_PENDING                  BIT(0)

/* Guest timer FIQ enable register */
#define SYS_IMP_APL_VM_TMR_FIQ_ENA_EL2  sys_reg(3, 5, 15, 1, 3)
#define VM_TMR_FIQ_ENABLE_V             BIT(0)
#define VM_TMR_FIQ_ENABLE_P             BIT(1)

/* Deferred IPI countdown register */
#define SYS_IMP_APL_IPI_CR_EL1          sys_reg(3, 5, 15, 3, 1)

/* Uncore PMC control register */
#define SYS_IMP_APL_UPMCR0_EL1          sys_reg(3, 7, 15, 0, 4)
#define UPMCR0_IMODE                    GENMASK(18, 16)
#define UPMCR0_IMODE_OFF                0
#define UPMCR0_IMODE_AIC                2
#define UPMCR0_IMODE_HALT               3
#define UPMCR0_IMODE_FIQ                4

/* Uncore PMC status register */
#define SYS_IMP_APL_UPMSR_EL1           sys_reg(3, 7, 15, 6, 4)
#define UPMSR_IACT                      BIT(0)

#define AIC_NR_FIQ              4
#define AIC_NR_SWIPI            32

/*
 * FIQ hwirq index definitions: FIQ sources use the DT binding defines
 * directly, except that timers are special. At the irqchip level, the
 * two timer types are represented by their access method: _EL0 registers
 * or _EL02 registers. In the DT binding, the timers are represented
 * by their purpose (HV or guest). This mapping is for when the kernel is
 * running at EL2 (with VHE). When the kernel is running at EL1, the
 * mapping differs and aic_irq_domain_translate() performs the remapping.
 */

#define AIC_TMR_EL0_PHYS        AIC_TMR_HV_PHYS
#define AIC_TMR_EL0_VIRT        AIC_TMR_HV_VIRT
#define AIC_TMR_EL02_PHYS       AIC_TMR_GUEST_PHYS
#define AIC_TMR_EL02_VIRT       AIC_TMR_GUEST_VIRT

struct aic_irq_chip {
        void __iomem *base;
        struct irq_domain *hw_domain;
        struct irq_domain *ipi_domain;
        int nr_hw;
        int ipi_hwirq;
};

static DEFINE_PER_CPU(uint32_t, aic_fiq_unmasked);

static DEFINE_PER_CPU(atomic_t, aic_vipi_flag);
static DEFINE_PER_CPU(atomic_t, aic_vipi_enable);

static struct aic_irq_chip *aic_irqc;

static void aic_handle_ipi(struct pt_regs *regs);

static u32 aic_ic_read(struct aic_irq_chip *ic, u32 reg)
{
        return readl_relaxed(ic->base + reg);
}

static void aic_ic_write(struct aic_irq_chip *ic, u32 reg, u32 val)
{
        writel_relaxed(val, ic->base + reg);
}

/*
 * IRQ irqchip
 */

static void aic_irq_mask(struct irq_data *d)
{
        struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);

        aic_ic_write(ic, AIC_MASK_SET + MASK_REG(irqd_to_hwirq(d)),
                     MASK_BIT(irqd_to_hwirq(d)));
}

static void aic_irq_unmask(struct irq_data *d)
{
        struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);

        aic_ic_write(ic, AIC_MASK_CLR + MASK_REG(d->hwirq),
                     MASK_BIT(irqd_to_hwirq(d)));
}

static void aic_irq_eoi(struct irq_data *d)
{
        /*
         * Reading the interrupt reason automatically acknowledges and masks
         * the IRQ, so we just unmask it here if needed.
         */
        if (!irqd_irq_disabled(d) && !irqd_irq_masked(d))
                aic_irq_unmask(d);
}

static void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
{
        struct aic_irq_chip *ic = aic_irqc;
        u32 event, type, irq;

        do {
                /*
                 * We cannot use a relaxed read here, as reads from DMA buffers
                 * need to be ordered after the IRQ fires.
                 */
                event = readl(ic->base + AIC_EVENT);
                type = FIELD_GET(AIC_EVENT_TYPE, event);
                irq = FIELD_GET(AIC_EVENT_NUM, event);

                if (type == AIC_EVENT_TYPE_HW)
                        handle_domain_irq(aic_irqc->hw_domain, irq, regs);
                else if (type == AIC_EVENT_TYPE_IPI && irq == 1)
                        aic_handle_ipi(regs);
                else if (event != 0)
                        pr_err_ratelimited("Unknown IRQ event %d, %d\n", type, irq);
        } while (event);

        /*
         * vGIC maintenance interrupts end up here too, so we need to check
         * for them separately. This should never trigger if KVM is working
         * properly, because it will have already taken care of clearing it
         * on guest exit before this handler runs.
         */
        if (is_kernel_in_hyp_mode() && (read_sysreg_s(SYS_ICH_HCR_EL2) & ICH_HCR_EN) &&
                read_sysreg_s(SYS_ICH_MISR_EL2) != 0) {
                pr_err_ratelimited("vGIC IRQ fired and not handled by KVM, disabling.\n");
                sysreg_clear_set_s(SYS_ICH_HCR_EL2, ICH_HCR_EN, 0);
        }
}

static int aic_irq_set_affinity(struct irq_data *d,
                                const struct cpumask *mask_val, bool force)
{
        irq_hw_number_t hwirq = irqd_to_hwirq(d);
        struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);
        int cpu;

        if (force)
                cpu = cpumask_first(mask_val);
        else
                cpu = cpumask_any_and(mask_val, cpu_online_mask);

        aic_ic_write(ic, AIC_TARGET_CPU + hwirq * 4, BIT(cpu));
        irq_data_update_effective_affinity(d, cpumask_of(cpu));

        return IRQ_SET_MASK_OK;
}

static int aic_irq_set_type(struct irq_data *d, unsigned int type)
{
        /*
         * Some IRQs (e.g. MSIs) implicitly have edge semantics, and we don't
         * have a way to find out the type of any given IRQ, so just allow both.
         */
        return (type == IRQ_TYPE_LEVEL_HIGH || type == IRQ_TYPE_EDGE_RISING) ? 0 : -EINVAL;
}

static struct irq_chip aic_chip = {
        .name = "AIC",
        .irq_mask = aic_irq_mask,
        .irq_unmask = aic_irq_unmask,
        .irq_eoi = aic_irq_eoi,
        .irq_set_affinity = aic_irq_set_affinity,
        .irq_set_type = aic_irq_set_type,
};

/*
 * FIQ irqchip
 */

static unsigned long aic_fiq_get_idx(struct irq_data *d)
{
        struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);

        return irqd_to_hwirq(d) - ic->nr_hw;
}

static void aic_fiq_set_mask(struct irq_data *d)
{
        /* Only the guest timers have real mask bits, unfortunately. */
        switch (aic_fiq_get_idx(d)) {
        case AIC_TMR_EL02_PHYS:
                sysreg_clear_set_s(SYS_IMP_APL_VM_TMR_FIQ_ENA_EL2, VM_TMR_FIQ_ENABLE_P, 0);
                isb();
                break;
        case AIC_TMR_EL02_VIRT:
                sysreg_clear_set_s(SYS_IMP_APL_VM_TMR_FIQ_ENA_EL2, VM_TMR_FIQ_ENABLE_V, 0);
                isb();
                break;
        default:
                break;
        }
}

static void aic_fiq_clear_mask(struct irq_data *d)
{
        switch (aic_fiq_get_idx(d)) {
        case AIC_TMR_EL02_PHYS:
                sysreg_clear_set_s(SYS_IMP_APL_VM_TMR_FIQ_ENA_EL2, 0, VM_TMR_FIQ_ENABLE_P);
                isb();
                break;
        case AIC_TMR_EL02_VIRT:
                sysreg_clear_set_s(SYS_IMP_APL_VM_TMR_FIQ_ENA_EL2, 0, VM_TMR_FIQ_ENABLE_V);
                isb();
                break;
        default:
                break;
        }
}

static void aic_fiq_mask(struct irq_data *d)
{
        aic_fiq_set_mask(d);
        __this_cpu_and(aic_fiq_unmasked, ~BIT(aic_fiq_get_idx(d)));
}

static void aic_fiq_unmask(struct irq_data *d)
{
        aic_fiq_clear_mask(d);
        __this_cpu_or(aic_fiq_unmasked, BIT(aic_fiq_get_idx(d)));
}

static void aic_fiq_eoi(struct irq_data *d)
{
        /* We mask to ack (where we can), so we need to unmask at EOI. */
        if (__this_cpu_read(aic_fiq_unmasked) & BIT(aic_fiq_get_idx(d)))
                aic_fiq_clear_mask(d);
}

#define TIMER_FIRING(x)                                                        \
        (((x) & (ARCH_TIMER_CTRL_ENABLE | ARCH_TIMER_CTRL_IT_MASK |            \
                 ARCH_TIMER_CTRL_IT_STAT)) ==                                  \
         (ARCH_TIMER_CTRL_ENABLE | ARCH_TIMER_CTRL_IT_STAT))

static void __exception_irq_entry aic_handle_fiq(struct pt_regs *regs)
{
        /*
         * It would be really nice if we had a system register that lets us get
         * the FIQ source state without having to peek down into sources...
         * but such a register does not seem to exist.
         *
         * So, we have these potential sources to test for:
         *  - Fast IPIs (not yet used)
         *  - The 4 timers (CNTP, CNTV for each of HV and guest)
         *  - Per-core PMCs (not yet supported)
         *  - Per-cluster uncore PMCs (not yet supported)
         *
         * Since not dealing with any of these results in a FIQ storm,
         * we check for everything here, even things we don't support yet.
         */

        if (read_sysreg_s(SYS_IMP_APL_IPI_SR_EL1) & IPI_SR_PENDING) {
                pr_err_ratelimited("Fast IPI fired. Acking.\n");
                write_sysreg_s(IPI_SR_PENDING, SYS_IMP_APL_IPI_SR_EL1);
        }

        if (TIMER_FIRING(read_sysreg(cntp_ctl_el0)))
                handle_domain_irq(aic_irqc->hw_domain,
                                  aic_irqc->nr_hw + AIC_TMR_EL0_PHYS, regs);

        if (TIMER_FIRING(read_sysreg(cntv_ctl_el0)))
                handle_domain_irq(aic_irqc->hw_domain,
                                  aic_irqc->nr_hw + AIC_TMR_EL0_VIRT, regs);

        if (is_kernel_in_hyp_mode()) {
                uint64_t enabled = read_sysreg_s(SYS_IMP_APL_VM_TMR_FIQ_ENA_EL2);

                if ((enabled & VM_TMR_FIQ_ENABLE_P) &&
                    TIMER_FIRING(read_sysreg_s(SYS_CNTP_CTL_EL02)))
                        handle_domain_irq(aic_irqc->hw_domain,
                                          aic_irqc->nr_hw + AIC_TMR_EL02_PHYS, regs);

                if ((enabled & VM_TMR_FIQ_ENABLE_V) &&
                    TIMER_FIRING(read_sysreg_s(SYS_CNTV_CTL_EL02)))
                        handle_domain_irq(aic_irqc->hw_domain,
                                          aic_irqc->nr_hw + AIC_TMR_EL02_VIRT, regs);
        }

        if ((read_sysreg_s(SYS_IMP_APL_PMCR0_EL1) & (PMCR0_IMODE | PMCR0_IACT)) ==
                        (FIELD_PREP(PMCR0_IMODE, PMCR0_IMODE_FIQ) | PMCR0_IACT)) {
                /*
                 * Not supported yet, let's figure out how to handle this when
                 * we implement these proprietary performance counters. For now,
                 * just mask it and move on.
                 */
                pr_err_ratelimited("PMC FIQ fired. Masking.\n");
                sysreg_clear_set_s(SYS_IMP_APL_PMCR0_EL1, PMCR0_IMODE | PMCR0_IACT,
                                   FIELD_PREP(PMCR0_IMODE, PMCR0_IMODE_OFF));
        }

        if (FIELD_GET(UPMCR0_IMODE, read_sysreg_s(SYS_IMP_APL_UPMCR0_EL1)) == UPMCR0_IMODE_FIQ &&
                        (read_sysreg_s(SYS_IMP_APL_UPMSR_EL1) & UPMSR_IACT)) {
                /* Same story with uncore PMCs */
                pr_err_ratelimited("Uncore PMC FIQ fired. Masking.\n");
                sysreg_clear_set_s(SYS_IMP_APL_UPMCR0_EL1, UPMCR0_IMODE,
                                   FIELD_PREP(UPMCR0_IMODE, UPMCR0_IMODE_OFF));
        }
}

static int aic_fiq_set_type(struct irq_data *d, unsigned int type)
{
        return (type == IRQ_TYPE_LEVEL_HIGH) ? 0 : -EINVAL;
}

static struct irq_chip fiq_chip = {
        .name = "AIC-FIQ",
        .irq_mask = aic_fiq_mask,
        .irq_unmask = aic_fiq_unmask,
        .irq_ack = aic_fiq_set_mask,
        .irq_eoi = aic_fiq_eoi,
        .irq_set_type = aic_fiq_set_type,
};

/*
 * Main IRQ domain
 */

static int aic_irq_domain_map(struct irq_domain *id, unsigned int irq,
                              irq_hw_number_t hw)
{
        struct aic_irq_chip *ic = id->host_data;

        if (hw < ic->nr_hw) {
                irq_domain_set_info(id, irq, hw, &aic_chip, id->host_data,
                                    handle_fasteoi_irq, NULL, NULL);
                irqd_set_single_target(irq_desc_get_irq_data(irq_to_desc(irq)));
        } else {
                irq_set_percpu_devid(irq);
                irq_domain_set_info(id, irq, hw, &fiq_chip, id->host_data,
                                    handle_percpu_devid_irq, NULL, NULL);
        }

        return 0;
}

static int aic_irq_domain_translate(struct irq_domain *id,
                                    struct irq_fwspec *fwspec,
                                    unsigned long *hwirq,
                                    unsigned int *type)
{
        struct aic_irq_chip *ic = id->host_data;

        if (fwspec->param_count != 3 || !is_of_node(fwspec->fwnode))
                return -EINVAL;

        switch (fwspec->param[0]) {
        case AIC_IRQ:
                if (fwspec->param[1] >= ic->nr_hw)
                        return -EINVAL;
                *hwirq = fwspec->param[1];
                break;
        case AIC_FIQ:
                if (fwspec->param[1] >= AIC_NR_FIQ)
                        return -EINVAL;
                *hwirq = ic->nr_hw + fwspec->param[1];

                /*
                 * In EL1 the non-redirected registers are the guest's,
                 * not EL2's, so remap the hwirqs to match.
                 */
                if (!is_kernel_in_hyp_mode()) {
                        switch (fwspec->param[1]) {
                        case AIC_TMR_GUEST_PHYS:
                                *hwirq = ic->nr_hw + AIC_TMR_EL0_PHYS;
                                break;
                        case AIC_TMR_GUEST_VIRT:
                                *hwirq = ic->nr_hw + AIC_TMR_EL0_VIRT;
                                break;
                        case AIC_TMR_HV_PHYS:
                        case AIC_TMR_HV_VIRT:
                                return -ENOENT;
                        default:
                                break;
                        }
                }
                break;
        default:
                return -EINVAL;
        }

        *type = fwspec->param[2] & IRQ_TYPE_SENSE_MASK;

        return 0;
}

static int aic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
                                unsigned int nr_irqs, void *arg)
{
        unsigned int type = IRQ_TYPE_NONE;
        struct irq_fwspec *fwspec = arg;
        irq_hw_number_t hwirq;
        int i, ret;

        ret = aic_irq_domain_translate(domain, fwspec, &hwirq, &type);
        if (ret)
                return ret;

        for (i = 0; i < nr_irqs; i++) {
                ret = aic_irq_domain_map(domain, virq + i, hwirq + i);
                if (ret)
                        return ret;
        }

        return 0;
}

static void aic_irq_domain_free(struct irq_domain *domain, unsigned int virq,
                                unsigned int nr_irqs)
{
        int i;

        for (i = 0; i < nr_irqs; i++) {
                struct irq_data *d = irq_domain_get_irq_data(domain, virq + i);

                irq_set_handler(virq + i, NULL);
                irq_domain_reset_irq_data(d);
        }
}

static const struct irq_domain_ops aic_irq_domain_ops = {
        .translate      = aic_irq_domain_translate,
        .alloc          = aic_irq_domain_alloc,
        .free           = aic_irq_domain_free,
};

/*
 * IPI irqchip
 */

static void aic_ipi_mask(struct irq_data *d)
{
        u32 irq_bit = BIT(irqd_to_hwirq(d));

        /* No specific ordering requirements needed here. */
        atomic_andnot(irq_bit, this_cpu_ptr(&aic_vipi_enable));
}

static void aic_ipi_unmask(struct irq_data *d)
{
        struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);
        u32 irq_bit = BIT(irqd_to_hwirq(d));

        atomic_or(irq_bit, this_cpu_ptr(&aic_vipi_enable));

        /*
         * The atomic_or() above must complete before the atomic_read()
         * below to avoid racing aic_ipi_send_mask().
         */
        smp_mb__after_atomic();

        /*
         * If a pending vIPI was unmasked, raise a HW IPI to ourselves.
         * No barriers needed here since this is a self-IPI.
         */
        if (atomic_read(this_cpu_ptr(&aic_vipi_flag)) & irq_bit)
                aic_ic_write(ic, AIC_IPI_SEND, AIC_IPI_SEND_CPU(smp_processor_id()));
}

static void aic_ipi_send_mask(struct irq_data *d, const struct cpumask *mask)
{
        struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);
        u32 irq_bit = BIT(irqd_to_hwirq(d));
        u32 send = 0;
        int cpu;
        unsigned long pending;

        for_each_cpu(cpu, mask) {
                /*
                 * This sequence is the mirror of the one in aic_ipi_unmask();
                 * see the comment there. Additionally, release semantics
                 * ensure that the vIPI flag set is ordered after any shared
                 * memory accesses that precede it. This therefore also pairs
                 * with the atomic_fetch_andnot in aic_handle_ipi().
                 */
                pending = atomic_fetch_or_release(irq_bit, per_cpu_ptr(&aic_vipi_flag, cpu));

                /*
                 * The atomic_fetch_or_release() above must complete before the
                 * atomic_read() below to avoid racing aic_ipi_unmask().
                 */
                smp_mb__after_atomic();

                if (!(pending & irq_bit) &&
                    (atomic_read(per_cpu_ptr(&aic_vipi_enable, cpu)) & irq_bit))
                        send |= AIC_IPI_SEND_CPU(cpu);
        }

        /*
         * The flag writes must complete before the physical IPI is issued
         * to another CPU. This is implied by the control dependency on
         * the result of atomic_read_acquire() above, which is itself
         * already ordered after the vIPI flag write.
         */
        if (send)
                aic_ic_write(ic, AIC_IPI_SEND, send);
}

static struct irq_chip ipi_chip = {
        .name = "AIC-IPI",
        .irq_mask = aic_ipi_mask,
        .irq_unmask = aic_ipi_unmask,
        .ipi_send_mask = aic_ipi_send_mask,
};

/*
 * IPI IRQ domain
 */

static void aic_handle_ipi(struct pt_regs *regs)
{
        int i;
        unsigned long enabled, firing;

        /*
         * Ack the IPI. We need to order this after the AIC event read, but
         * that is enforced by normal MMIO ordering guarantees.
         */
        aic_ic_write(aic_irqc, AIC_IPI_ACK, AIC_IPI_OTHER);

        /*
         * The mask read does not need to be ordered. Only we can change
         * our own mask anyway, so no races are possible here, as long as
         * we are properly in the interrupt handler (which is covered by
         * the barrier that is part of the top-level AIC handler's readl()).
         */
        enabled = atomic_read(this_cpu_ptr(&aic_vipi_enable));

        /*
         * Clear the IPIs we are about to handle. This pairs with the
         * atomic_fetch_or_release() in aic_ipi_send_mask(), and needs to be
         * ordered after the aic_ic_write() above (to avoid dropping vIPIs) and
         * before IPI handling code (to avoid races handling vIPIs before they
         * are signaled). The former is taken care of by the release semantics
         * of the write portion, while the latter is taken care of by the
         * acquire semantics of the read portion.
         */
        firing = atomic_fetch_andnot(enabled, this_cpu_ptr(&aic_vipi_flag)) & enabled;

        for_each_set_bit(i, &firing, AIC_NR_SWIPI)
                handle_domain_irq(aic_irqc->ipi_domain, i, regs);

        /*
         * No ordering needed here; at worst this just changes the timing of
         * when the next IPI will be delivered.
         */
        aic_ic_write(aic_irqc, AIC_IPI_MASK_CLR, AIC_IPI_OTHER);
}

static int aic_ipi_alloc(struct irq_domain *d, unsigned int virq,
                         unsigned int nr_irqs, void *args)
{
        int i;

        for (i = 0; i < nr_irqs; i++) {
                irq_set_percpu_devid(virq + i);
                irq_domain_set_info(d, virq + i, i, &ipi_chip, d->host_data,
                                    handle_percpu_devid_irq, NULL, NULL);
        }

        return 0;
}

static void aic_ipi_free(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs)
{
        /* Not freeing IPIs */
}

static const struct irq_domain_ops aic_ipi_domain_ops = {
        .alloc = aic_ipi_alloc,
        .free = aic_ipi_free,
};

static int aic_init_smp(struct aic_irq_chip *irqc, struct device_node *node)
{
        struct irq_domain *ipi_domain;
        int base_ipi;

        ipi_domain = irq_domain_create_linear(irqc->hw_domain->fwnode, AIC_NR_SWIPI,
                                              &aic_ipi_domain_ops, irqc);
        if (WARN_ON(!ipi_domain))
                return -ENODEV;

        ipi_domain->flags |= IRQ_DOMAIN_FLAG_IPI_SINGLE;
        irq_domain_update_bus_token(ipi_domain, DOMAIN_BUS_IPI);

        base_ipi = __irq_domain_alloc_irqs(ipi_domain, -1, AIC_NR_SWIPI,
                                           NUMA_NO_NODE, NULL, false, NULL);

        if (WARN_ON(!base_ipi)) {
                irq_domain_remove(ipi_domain);
                return -ENODEV;
        }

        set_smp_ipi_range(base_ipi, AIC_NR_SWIPI);

        irqc->ipi_domain = ipi_domain;

        return 0;
}

static int aic_init_cpu(unsigned int cpu)
{
        /* Mask all hard-wired per-CPU IRQ/FIQ sources */

        /* Pending Fast IPI FIQs */
        write_sysreg_s(IPI_SR_PENDING, SYS_IMP_APL_IPI_SR_EL1);

        /* Timer FIQs */
        sysreg_clear_set(cntp_ctl_el0, 0, ARCH_TIMER_CTRL_IT_MASK);
        sysreg_clear_set(cntv_ctl_el0, 0, ARCH_TIMER_CTRL_IT_MASK);

        /* EL2-only (VHE mode) IRQ sources */
        if (is_kernel_in_hyp_mode()) {
                /* Guest timers */
                sysreg_clear_set_s(SYS_IMP_APL_VM_TMR_FIQ_ENA_EL2,
                                   VM_TMR_FIQ_ENABLE_V | VM_TMR_FIQ_ENABLE_P, 0);

                /* vGIC maintenance IRQ */
                sysreg_clear_set_s(SYS_ICH_HCR_EL2, ICH_HCR_EN, 0);
        }

        /* PMC FIQ */
        sysreg_clear_set_s(SYS_IMP_APL_PMCR0_EL1, PMCR0_IMODE | PMCR0_IACT,
                           FIELD_PREP(PMCR0_IMODE, PMCR0_IMODE_OFF));

        /* Uncore PMC FIQ */
        sysreg_clear_set_s(SYS_IMP_APL_UPMCR0_EL1, UPMCR0_IMODE,
                           FIELD_PREP(UPMCR0_IMODE, UPMCR0_IMODE_OFF));

        /* Commit all of the above */
        isb();

        /*
         * Make sure the kernel's idea of logical CPU order is the same as AIC's
         * If we ever end up with a mismatch here, we will have to introduce
         * a mapping table similar to what other irqchip drivers do.
         */
        WARN_ON(aic_ic_read(aic_irqc, AIC_WHOAMI) != smp_processor_id());

        /*
         * Always keep IPIs unmasked at the hardware level (except auto-masking
         * by AIC during processing). We manage masks at the vIPI level.
         */
        aic_ic_write(aic_irqc, AIC_IPI_ACK, AIC_IPI_SELF | AIC_IPI_OTHER);
        aic_ic_write(aic_irqc, AIC_IPI_MASK_SET, AIC_IPI_SELF);
        aic_ic_write(aic_irqc, AIC_IPI_MASK_CLR, AIC_IPI_OTHER);

        /* Initialize the local mask state */
        __this_cpu_write(aic_fiq_unmasked, 0);

        return 0;
}

static int __init aic_of_ic_init(struct device_node *node, struct device_node *parent)
{
        int i;
        void __iomem *regs;
        u32 info;
        struct aic_irq_chip *irqc;

        regs = of_iomap(node, 0);
        if (WARN_ON(!regs))
                return -EIO;

        irqc = kzalloc(sizeof(*irqc), GFP_KERNEL);
        if (!irqc)
                return -ENOMEM;

        aic_irqc = irqc;
        irqc->base = regs;

        info = aic_ic_read(irqc, AIC_INFO);
        irqc->nr_hw = FIELD_GET(AIC_INFO_NR_HW, info);

        irqc->hw_domain = irq_domain_create_linear(of_node_to_fwnode(node),
                                                   irqc->nr_hw + AIC_NR_FIQ,
                                                   &aic_irq_domain_ops, irqc);
        if (WARN_ON(!irqc->hw_domain)) {
                iounmap(irqc->base);
                kfree(irqc);
                return -ENODEV;
        }

        irq_domain_update_bus_token(irqc->hw_domain, DOMAIN_BUS_WIRED);

        if (aic_init_smp(irqc, node)) {
                irq_domain_remove(irqc->hw_domain);
                iounmap(irqc->base);
                kfree(irqc);
                return -ENODEV;
        }

        set_handle_irq(aic_handle_irq);
        set_handle_fiq(aic_handle_fiq);

        for (i = 0; i < BITS_TO_U32(irqc->nr_hw); i++)
                aic_ic_write(irqc, AIC_MASK_SET + i * 4, U32_MAX);
        for (i = 0; i < BITS_TO_U32(irqc->nr_hw); i++)
                aic_ic_write(irqc, AIC_SW_CLR + i * 4, U32_MAX);
        for (i = 0; i < irqc->nr_hw; i++)
                aic_ic_write(irqc, AIC_TARGET_CPU + i * 4, 1);

        if (!is_kernel_in_hyp_mode())
                pr_info("Kernel running in EL1, mapping interrupts");

        cpuhp_setup_state(CPUHP_AP_IRQ_APPLE_AIC_STARTING,
                          "irqchip/apple-aic/ipi:starting",
                          aic_init_cpu, NULL);

        pr_info("Initialized with %d IRQs, %d FIQs, %d vIPIs\n",
                irqc->nr_hw, AIC_NR_FIQ, AIC_NR_SWIPI);

        return 0;
}

IRQCHIP_DECLARE(apple_m1_aic, "apple,aic", aic_of_ic_init);