/*
 * Hisilicon HiP04 INTC
 *
 * Copyright (C) 2002-2014 ARM Limited.
 * Copyright (c) 2013-2014 Hisilicon Ltd.
 * Copyright (c) 2013-2014 Linaro Ltd.
 *
 * 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.
 *
 * Interrupt architecture for the HIP04 INTC:
 *
 * o There is one Interrupt Distributor, which receives interrupts
 *   from system devices and sends them to the Interrupt Controllers.
 *
 * o There is one CPU Interface per CPU, which sends interrupts sent
 *   by the Distributor, and interrupts generated locally, to the
 *   associated CPU. The base address of the CPU interface is usually
 *   aliased so that the same address points to different chips depending
 *   on the CPU it is accessed from.
 *
 * Note that IRQs 0-31 are special - they are local to each CPU.
 * As such, the enable set/clear, pending set/clear and active bit
 * registers are banked per-cpu for these sources.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/cpumask.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/irqdomain.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/irqchip.h>
#include <linux/irqchip/arm-gic.h>

#include <asm/irq.h>
#include <asm/exception.h>
#include <asm/smp_plat.h>

#include "irq-gic-common.h"

#define HIP04_MAX_IRQS          510

struct hip04_irq_data {
        void __iomem *dist_base;
        void __iomem *cpu_base;
        struct irq_domain *domain;
        unsigned int nr_irqs;
};

static DEFINE_RAW_SPINLOCK(irq_controller_lock);

/*
 * The GIC mapping of CPU interfaces does not necessarily match
 * the logical CPU numbering.  Let's use a mapping as returned
 * by the GIC itself.
 */
#define NR_HIP04_CPU_IF 16
static u16 hip04_cpu_map[NR_HIP04_CPU_IF] __read_mostly;

static struct hip04_irq_data hip04_data __read_mostly;

static inline void __iomem *hip04_dist_base(struct irq_data *d)
{
        struct hip04_irq_data *hip04_data = irq_data_get_irq_chip_data(d);
        return hip04_data->dist_base;
}

static inline void __iomem *hip04_cpu_base(struct irq_data *d)
{
        struct hip04_irq_data *hip04_data = irq_data_get_irq_chip_data(d);
        return hip04_data->cpu_base;
}

static inline unsigned int hip04_irq(struct irq_data *d)
{
        return d->hwirq;
}

/*
 * Routines to acknowledge, disable and enable interrupts
 */
static void hip04_mask_irq(struct irq_data *d)
{
        u32 mask = 1 << (hip04_irq(d) % 32);

        raw_spin_lock(&irq_controller_lock);
        writel_relaxed(mask, hip04_dist_base(d) + GIC_DIST_ENABLE_CLEAR +
                       (hip04_irq(d) / 32) * 4);
        raw_spin_unlock(&irq_controller_lock);
}

static void hip04_unmask_irq(struct irq_data *d)
{
        u32 mask = 1 << (hip04_irq(d) % 32);

        raw_spin_lock(&irq_controller_lock);
        writel_relaxed(mask, hip04_dist_base(d) + GIC_DIST_ENABLE_SET +
                       (hip04_irq(d) / 32) * 4);
        raw_spin_unlock(&irq_controller_lock);
}

static void hip04_eoi_irq(struct irq_data *d)
{
        writel_relaxed(hip04_irq(d), hip04_cpu_base(d) + GIC_CPU_EOI);
}

static int hip04_irq_set_type(struct irq_data *d, unsigned int type)
{
        void __iomem *base = hip04_dist_base(d);
        unsigned int irq = hip04_irq(d);
        int ret;

        /* Interrupt configuration for SGIs can't be changed */
        if (irq < 16)
                return -EINVAL;

        /* SPIs have restrictions on the supported types */
        if (irq >= 32 && type != IRQ_TYPE_LEVEL_HIGH &&
                         type != IRQ_TYPE_EDGE_RISING)
                return -EINVAL;

        raw_spin_lock(&irq_controller_lock);

        ret = gic_configure_irq(irq, type, base, NULL);

        raw_spin_unlock(&irq_controller_lock);

        return ret;
}

#ifdef CONFIG_SMP
static int hip04_irq_set_affinity(struct irq_data *d,
                                  const struct cpumask *mask_val,
                                  bool force)
{
        void __iomem *reg;
        unsigned int cpu, shift = (hip04_irq(d) % 2) * 16;
        u32 val, mask, bit;

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

        if (cpu >= NR_HIP04_CPU_IF || cpu >= nr_cpu_ids)
                return -EINVAL;

        raw_spin_lock(&irq_controller_lock);
        reg = hip04_dist_base(d) + GIC_DIST_TARGET + ((hip04_irq(d) * 2) & ~3);
        mask = 0xffff << shift;
        bit = hip04_cpu_map[cpu] << shift;
        val = readl_relaxed(reg) & ~mask;
        writel_relaxed(val | bit, reg);
        raw_spin_unlock(&irq_controller_lock);

        return IRQ_SET_MASK_OK;
}
#endif

static void __exception_irq_entry hip04_handle_irq(struct pt_regs *regs)
{
        u32 irqstat, irqnr;
        void __iomem *cpu_base = hip04_data.cpu_base;

        do {
                irqstat = readl_relaxed(cpu_base + GIC_CPU_INTACK);
                irqnr = irqstat & GICC_IAR_INT_ID_MASK;

                if (likely(irqnr > 15 && irqnr <= HIP04_MAX_IRQS)) {
                        handle_domain_irq(hip04_data.domain, irqnr, regs);
                        continue;
                }
                if (irqnr < 16) {
                        writel_relaxed(irqstat, cpu_base + GIC_CPU_EOI);
#ifdef CONFIG_SMP
                        handle_IPI(irqnr, regs);
#endif
                        continue;
                }
                break;
        } while (1);
}

static struct irq_chip hip04_irq_chip = {
        .name                   = "HIP04 INTC",
        .irq_mask               = hip04_mask_irq,
        .irq_unmask             = hip04_unmask_irq,
        .irq_eoi                = hip04_eoi_irq,
        .irq_set_type           = hip04_irq_set_type,
#ifdef CONFIG_SMP
        .irq_set_affinity       = hip04_irq_set_affinity,
#endif
        .flags                  = IRQCHIP_SET_TYPE_MASKED |
                                  IRQCHIP_SKIP_SET_WAKE |
                                  IRQCHIP_MASK_ON_SUSPEND,
};

static u16 hip04_get_cpumask(struct hip04_irq_data *intc)
{
        void __iomem *base = intc->dist_base;
        u32 mask, i;

        for (i = mask = 0; i < 32; i += 2) {
                mask = readl_relaxed(base + GIC_DIST_TARGET + i * 2);
                mask |= mask >> 16;
                if (mask)
                        break;
        }

        if (!mask)
                pr_crit("GIC CPU mask not found - kernel will fail to boot.\n");

        return mask;
}

static void __init hip04_irq_dist_init(struct hip04_irq_data *intc)
{
        unsigned int i;
        u32 cpumask;
        unsigned int nr_irqs = intc->nr_irqs;
        void __iomem *base = intc->dist_base;

        writel_relaxed(0, base + GIC_DIST_CTRL);

        /*
         * Set all global interrupts to this CPU only.
         */
        cpumask = hip04_get_cpumask(intc);
        cpumask |= cpumask << 16;
        for (i = 32; i < nr_irqs; i += 2)
                writel_relaxed(cpumask, base + GIC_DIST_TARGET + ((i * 2) & ~3));

        gic_dist_config(base, nr_irqs, NULL);

        writel_relaxed(1, base + GIC_DIST_CTRL);
}

static void hip04_irq_cpu_init(struct hip04_irq_data *intc)
{
        void __iomem *dist_base = intc->dist_base;
        void __iomem *base = intc->cpu_base;
        unsigned int cpu_mask, cpu = smp_processor_id();
        int i;

        /*
         * Get what the GIC says our CPU mask is.
         */
        BUG_ON(cpu >= NR_HIP04_CPU_IF);
        cpu_mask = hip04_get_cpumask(intc);
        hip04_cpu_map[cpu] = cpu_mask;

        /*
         * Clear our mask from the other map entries in case they're
         * still undefined.
         */
        for (i = 0; i < NR_HIP04_CPU_IF; i++)
                if (i != cpu)
                        hip04_cpu_map[i] &= ~cpu_mask;

        gic_cpu_config(dist_base, NULL);

        writel_relaxed(0xf0, base + GIC_CPU_PRIMASK);
        writel_relaxed(1, base + GIC_CPU_CTRL);
}

#ifdef CONFIG_SMP
static void hip04_raise_softirq(const struct cpumask *mask, unsigned int irq)
{
        int cpu;
        unsigned long flags, map = 0;

        raw_spin_lock_irqsave(&irq_controller_lock, flags);

        /* Convert our logical CPU mask into a physical one. */
        for_each_cpu(cpu, mask)
                map |= hip04_cpu_map[cpu];

        /*
         * Ensure that stores to Normal memory are visible to the
         * other CPUs before they observe us issuing the IPI.
         */
        dmb(ishst);

        /* this always happens on GIC0 */
        writel_relaxed(map << 8 | irq, hip04_data.dist_base + GIC_DIST_SOFTINT);

        raw_spin_unlock_irqrestore(&irq_controller_lock, flags);
}
#endif

static int hip04_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, &hip04_irq_chip,
                                         handle_percpu_devid_irq);
                irq_set_status_flags(irq, IRQ_NOAUTOEN);
        } else {
                irq_set_chip_and_handler(irq, &hip04_irq_chip,
                                         handle_fasteoi_irq);
                irq_set_probe(irq);
        }
        irq_set_chip_data(irq, d->host_data);
        return 0;
}

static int hip04_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)
{
        unsigned long ret = 0;

        if (irq_domain_get_of_node(d) != controller)
                return -EINVAL;
        if (intsize < 3)
                return -EINVAL;

        /* Get the interrupt number and add 16 to skip over SGIs */
        *out_hwirq = intspec[1] + 16;

        /* For SPIs, we need to add 16 more to get the irq ID number */
        if (!intspec[0])
                *out_hwirq += 16;

        *out_type = intspec[2] & IRQ_TYPE_SENSE_MASK;

        return ret;
}

static int hip04_irq_starting_cpu(unsigned int cpu)
{
        hip04_irq_cpu_init(&hip04_data);
        return 0;
}

static const struct irq_domain_ops hip04_irq_domain_ops = {
        .map    = hip04_irq_domain_map,
        .xlate  = hip04_irq_domain_xlate,
};

static int __init
hip04_of_init(struct device_node *node, struct device_node *parent)
{
        irq_hw_number_t hwirq_base = 16;
        int nr_irqs, irq_base, i;

        if (WARN_ON(!node))
                return -ENODEV;

        hip04_data.dist_base = of_iomap(node, 0);
        WARN(!hip04_data.dist_base, "fail to map hip04 intc dist registers\n");

        hip04_data.cpu_base = of_iomap(node, 1);
        WARN(!hip04_data.cpu_base, "unable to map hip04 intc cpu registers\n");

        /*
         * Initialize the CPU interface map to all CPUs.
         * It will be refined as each CPU probes its ID.
         */
        for (i = 0; i < NR_HIP04_CPU_IF; i++)
                hip04_cpu_map[i] = 0xffff;

        /*
         * Find out how many interrupts are supported.
         * The HIP04 INTC only supports up to 510 interrupt sources.
         */
        nr_irqs = readl_relaxed(hip04_data.dist_base + GIC_DIST_CTR) & 0x1f;
        nr_irqs = (nr_irqs + 1) * 32;
        if (nr_irqs > HIP04_MAX_IRQS)
                nr_irqs = HIP04_MAX_IRQS;
        hip04_data.nr_irqs = nr_irqs;

        nr_irqs -= hwirq_base; /* calculate # of irqs to allocate */

        irq_base = irq_alloc_descs(-1, hwirq_base, nr_irqs, numa_node_id());
        if (irq_base < 0) {
                pr_err("failed to allocate IRQ numbers\n");
                return -EINVAL;
        }

        hip04_data.domain = irq_domain_add_legacy(node, nr_irqs, irq_base,
                                                  hwirq_base,
                                                  &hip04_irq_domain_ops,
                                                  &hip04_data);

        if (WARN_ON(!hip04_data.domain))
                return -EINVAL;

#ifdef CONFIG_SMP
        set_smp_cross_call(hip04_raise_softirq);
#endif
        set_handle_irq(hip04_handle_irq);

        hip04_irq_dist_init(&hip04_data);
        cpuhp_setup_state(CPUHP_AP_IRQ_HIP04_STARTING, "irqchip/hip04:starting",
                          hip04_irq_starting_cpu, NULL);
        return 0;
}
IRQCHIP_DECLARE(hip04_intc, "hisilicon,hip04-intc", hip04_of_init);