/*
 * Copyright (C) 2016 ARM Limited, All Rights Reserved.
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 *
 * 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/bitops.h>
#include <linux/interrupt.h>
#include <linux/irqchip.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqchip/irq-partition-percpu.h>
#include <linux/irqdomain.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

struct partition_desc {
        int                             nr_parts;
        struct partition_affinity       *parts;
        struct irq_domain               *domain;
        struct irq_desc                 *chained_desc;
        unsigned long                   *bitmap;
        struct irq_domain_ops           ops;
};

static bool partition_check_cpu(struct partition_desc *part,
                                unsigned int cpu, unsigned int hwirq)
{
        return cpumask_test_cpu(cpu, &part->parts[hwirq].mask);
}

static void partition_irq_mask(struct irq_data *d)
{
        struct partition_desc *part = irq_data_get_irq_chip_data(d);
        struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);
        struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);

        if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&
            chip->irq_mask)
                chip->irq_mask(data);
}

static void partition_irq_unmask(struct irq_data *d)
{
        struct partition_desc *part = irq_data_get_irq_chip_data(d);
        struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);
        struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);

        if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&
            chip->irq_unmask)
                chip->irq_unmask(data);
}

static int partition_irq_set_irqchip_state(struct irq_data *d,
                                           enum irqchip_irq_state which,
                                           bool val)
{
        struct partition_desc *part = irq_data_get_irq_chip_data(d);
        struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);
        struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);

        if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&
            chip->irq_set_irqchip_state)
                return chip->irq_set_irqchip_state(data, which, val);

        return -EINVAL;
}

static int partition_irq_get_irqchip_state(struct irq_data *d,
                                           enum irqchip_irq_state which,
                                           bool *val)
{
        struct partition_desc *part = irq_data_get_irq_chip_data(d);
        struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);
        struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);

        if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&
            chip->irq_get_irqchip_state)
                return chip->irq_get_irqchip_state(data, which, val);

        return -EINVAL;
}

static int partition_irq_set_type(struct irq_data *d, unsigned int type)
{
        struct partition_desc *part = irq_data_get_irq_chip_data(d);
        struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);
        struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);

        if (chip->irq_set_type)
                return chip->irq_set_type(data, type);

        return -EINVAL;
}

static void partition_irq_print_chip(struct irq_data *d, struct seq_file *p)
{
        struct partition_desc *part = irq_data_get_irq_chip_data(d);
        struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);
        struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);

        seq_printf(p, " %5s-%lu", chip->name, data->hwirq);
}

static struct irq_chip partition_irq_chip = {
        .irq_mask               = partition_irq_mask,
        .irq_unmask             = partition_irq_unmask,
        .irq_set_type           = partition_irq_set_type,
        .irq_get_irqchip_state  = partition_irq_get_irqchip_state,
        .irq_set_irqchip_state  = partition_irq_set_irqchip_state,
        .irq_print_chip         = partition_irq_print_chip,
};

static void partition_handle_irq(struct irq_desc *desc)
{
        struct partition_desc *part = irq_desc_get_handler_data(desc);
        struct irq_chip *chip = irq_desc_get_chip(desc);
        int cpu = smp_processor_id();
        int hwirq;

        chained_irq_enter(chip, desc);

        for_each_set_bit(hwirq, part->bitmap, part->nr_parts) {
                if (partition_check_cpu(part, cpu, hwirq))
                        break;
        }

        if (unlikely(hwirq == part->nr_parts)) {
                handle_bad_irq(desc);
        } else {
                unsigned int irq;
                irq = irq_find_mapping(part->domain, hwirq);
                generic_handle_irq(irq);
        }

        chained_irq_exit(chip, desc);
}

static int partition_domain_alloc(struct irq_domain *domain, unsigned int virq,
                                  unsigned int nr_irqs, void *arg)
{
        int ret;
        irq_hw_number_t hwirq;
        unsigned int type;
        struct irq_fwspec *fwspec = arg;
        struct partition_desc *part;

        BUG_ON(nr_irqs != 1);
        ret = domain->ops->translate(domain, fwspec, &hwirq, &type);
        if (ret)
                return ret;

        part = domain->host_data;

        set_bit(hwirq, part->bitmap);
        irq_set_chained_handler_and_data(irq_desc_get_irq(part->chained_desc),
                                         partition_handle_irq, part);
        irq_set_percpu_devid_partition(virq, &part->parts[hwirq].mask);
        irq_domain_set_info(domain, virq, hwirq, &partition_irq_chip, part,
                            handle_percpu_devid_irq, NULL, NULL);
        irq_set_status_flags(virq, IRQ_NOAUTOEN);

        return 0;
}

static void partition_domain_free(struct irq_domain *domain, unsigned int virq,
                                  unsigned int nr_irqs)
{
        struct irq_data *d;

        BUG_ON(nr_irqs != 1);

        d = irq_domain_get_irq_data(domain, virq);
        irq_set_handler(virq, NULL);
        irq_domain_reset_irq_data(d);
}

int partition_translate_id(struct partition_desc *desc, void *partition_id)
{
        struct partition_affinity *part = NULL;
        int i;

        for (i = 0; i < desc->nr_parts; i++) {
                if (desc->parts[i].partition_id == partition_id) {
                        part = &desc->parts[i];
                        break;
                }
        }

        if (WARN_ON(!part)) {
                pr_err("Failed to find partition\n");
                return -EINVAL;
        }

        return i;
}

struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode,
                                             struct partition_affinity *parts,
                                             int nr_parts,
                                             int chained_irq,
                                             const struct irq_domain_ops *ops)
{
        struct partition_desc *desc;
        struct irq_domain *d;

        BUG_ON(!ops->select || !ops->translate);

        desc = kzalloc(sizeof(*desc), GFP_KERNEL);
        if (!desc)
                return NULL;

        desc->ops = *ops;
        desc->ops.free = partition_domain_free;
        desc->ops.alloc = partition_domain_alloc;

        d = irq_domain_create_linear(fwnode, nr_parts, &desc->ops, desc);
        if (!d)
                goto out;
        desc->domain = d;

        desc->bitmap = kcalloc(BITS_TO_LONGS(nr_parts), sizeof(long),
                               GFP_KERNEL);
        if (WARN_ON(!desc->bitmap))
                goto out;

        desc->chained_desc = irq_to_desc(chained_irq);
        desc->nr_parts = nr_parts;
        desc->parts = parts;

        return desc;
out:
        if (d)
                irq_domain_remove(d);
        kfree(desc);

        return NULL;
}

struct irq_domain *partition_get_domain(struct partition_desc *dsc)
{
        if (dsc)
                return dsc->domain;

        return NULL;
}