/*
 *  drivers/irqchip/irq-crossbar.c
 *
 *  Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
 *  Author: Sricharan R <r.sricharan@ti.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.
 *
 */
#include <linux/err.h>
#include <linux/io.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/slab.h>

#define IRQ_FREE        -1
#define IRQ_RESERVED    -2
#define IRQ_SKIP        -3
#define GIC_IRQ_START   32

/**
 * struct crossbar_device - crossbar device description
 * @lock: spinlock serializing access to @irq_map
 * @int_max: maximum number of supported interrupts
 * @safe_map: safe default value to initialize the crossbar
 * @max_crossbar_sources: Maximum number of crossbar sources
 * @irq_map: array of interrupts to crossbar number mapping
 * @crossbar_base: crossbar base address
 * @register_offsets: offsets for each irq number
 * @write: register write function pointer
 */
struct crossbar_device {
        raw_spinlock_t lock;
        uint int_max;
        uint safe_map;
        uint max_crossbar_sources;
        uint *irq_map;
        void __iomem *crossbar_base;
        int *register_offsets;
        void (*write)(int, int);
};

static struct crossbar_device *cb;

static void crossbar_writel(int irq_no, int cb_no)
{
        writel(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
}

static void crossbar_writew(int irq_no, int cb_no)
{
        writew(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
}

static void crossbar_writeb(int irq_no, int cb_no)
{
        writeb(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
}

static struct irq_chip crossbar_chip = {
        .name                   = "CBAR",
        .irq_eoi                = irq_chip_eoi_parent,
        .irq_mask               = irq_chip_mask_parent,
        .irq_unmask             = irq_chip_unmask_parent,
        .irq_retrigger          = irq_chip_retrigger_hierarchy,
        .irq_set_type           = irq_chip_set_type_parent,
        .flags                  = IRQCHIP_MASK_ON_SUSPEND |
                                  IRQCHIP_SKIP_SET_WAKE,
#ifdef CONFIG_SMP
        .irq_set_affinity       = irq_chip_set_affinity_parent,
#endif
};

static int allocate_gic_irq(struct irq_domain *domain, unsigned virq,
                            irq_hw_number_t hwirq)
{
        struct irq_fwspec fwspec;
        int i;
        int err;

        if (!irq_domain_get_of_node(domain->parent))
                return -EINVAL;

        raw_spin_lock(&cb->lock);
        for (i = cb->int_max - 1; i >= 0; i--) {
                if (cb->irq_map[i] == IRQ_FREE) {
                        cb->irq_map[i] = hwirq;
                        break;
                }
        }
        raw_spin_unlock(&cb->lock);

        if (i < 0)
                return -ENODEV;

        fwspec.fwnode = domain->parent->fwnode;
        fwspec.param_count = 3;
        fwspec.param[0] = 0;    /* SPI */
        fwspec.param[1] = i;
        fwspec.param[2] = IRQ_TYPE_LEVEL_HIGH;

        err = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
        if (err)
                cb->irq_map[i] = IRQ_FREE;
        else
                cb->write(i, hwirq);

        return err;
}

static int crossbar_domain_alloc(struct irq_domain *d, unsigned int virq,
                                 unsigned int nr_irqs, void *data)
{
        struct irq_fwspec *fwspec = data;
        irq_hw_number_t hwirq;
        int i;

        if (fwspec->param_count != 3)
                return -EINVAL; /* Not GIC compliant */
        if (fwspec->param[0] != 0)
                return -EINVAL; /* No PPI should point to this domain */

        hwirq = fwspec->param[1];
        if ((hwirq + nr_irqs) > cb->max_crossbar_sources)
                return -EINVAL; /* Can't deal with this */

        for (i = 0; i < nr_irqs; i++) {
                int err = allocate_gic_irq(d, virq + i, hwirq + i);

                if (err)
                        return err;

                irq_domain_set_hwirq_and_chip(d, virq + i, hwirq + i,
                                              &crossbar_chip, NULL);
        }

        return 0;
}

/**
 * crossbar_domain_free - unmap/free a crossbar<->irq connection
 * @domain: domain of irq to unmap
 * @virq: virq number
 * @nr_irqs: number of irqs to free
 *
 * We do not maintain a use count of total number of map/unmap
 * calls for a particular irq to find out if a irq can be really
 * unmapped. This is because unmap is called during irq_dispose_mapping(irq),
 * after which irq is anyways unusable. So an explicit map has to be called
 * after that.
 */
static void crossbar_domain_free(struct irq_domain *domain, unsigned int virq,
                                 unsigned int nr_irqs)
{
        int i;

        raw_spin_lock(&cb->lock);
        for (i = 0; i < nr_irqs; i++) {
                struct irq_data *d = irq_domain_get_irq_data(domain, virq + i);

                irq_domain_reset_irq_data(d);
                cb->irq_map[d->hwirq] = IRQ_FREE;
                cb->write(d->hwirq, cb->safe_map);
        }
        raw_spin_unlock(&cb->lock);
}

static int crossbar_domain_translate(struct irq_domain *d,
                                     struct irq_fwspec *fwspec,
                                     unsigned long *hwirq,
                                     unsigned int *type)
{
        if (is_of_node(fwspec->fwnode)) {
                if (fwspec->param_count != 3)
                        return -EINVAL;

                /* No PPI should point to this domain */
                if (fwspec->param[0] != 0)
                        return -EINVAL;

                *hwirq = fwspec->param[1];
                *type = fwspec->param[2] & IRQ_TYPE_SENSE_MASK;
                return 0;
        }

        return -EINVAL;
}

static const struct irq_domain_ops crossbar_domain_ops = {
        .alloc          = crossbar_domain_alloc,
        .free           = crossbar_domain_free,
        .translate      = crossbar_domain_translate,
};

static int __init crossbar_of_init(struct device_node *node)
{
        int i, size, max = 0, reserved = 0, entry;
        const __be32 *irqsr;
        int ret = -ENOMEM;

        cb = kzalloc(sizeof(*cb), GFP_KERNEL);

        if (!cb)
                return ret;

        cb->crossbar_base = of_iomap(node, 0);
        if (!cb->crossbar_base)
                goto err_cb;

        of_property_read_u32(node, "ti,max-crossbar-sources",
                             &cb->max_crossbar_sources);
        if (!cb->max_crossbar_sources) {
                pr_err("missing 'ti,max-crossbar-sources' property\n");
                ret = -EINVAL;
                goto err_base;
        }

        of_property_read_u32(node, "ti,max-irqs", &max);
        if (!max) {
                pr_err("missing 'ti,max-irqs' property\n");
                ret = -EINVAL;
                goto err_base;
        }
        cb->irq_map = kcalloc(max, sizeof(int), GFP_KERNEL);
        if (!cb->irq_map)
                goto err_base;

        cb->int_max = max;

        for (i = 0; i < max; i++)
                cb->irq_map[i] = IRQ_FREE;

        /* Get and mark reserved irqs */
        irqsr = of_get_property(node, "ti,irqs-reserved", &size);
        if (irqsr) {
                size /= sizeof(__be32);

                for (i = 0; i < size; i++) {
                        of_property_read_u32_index(node,
                                                   "ti,irqs-reserved",
                                                   i, &entry);
                        if (entry >= max) {
                                pr_err("Invalid reserved entry\n");
                                ret = -EINVAL;
                                goto err_irq_map;
                        }
                        cb->irq_map[entry] = IRQ_RESERVED;
                }
        }

        /* Skip irqs hardwired to bypass the crossbar */
        irqsr = of_get_property(node, "ti,irqs-skip", &size);
        if (irqsr) {
                size /= sizeof(__be32);

                for (i = 0; i < size; i++) {
                        of_property_read_u32_index(node,
                                                   "ti,irqs-skip",
                                                   i, &entry);
                        if (entry >= max) {
                                pr_err("Invalid skip entry\n");
                                ret = -EINVAL;
                                goto err_irq_map;
                        }
                        cb->irq_map[entry] = IRQ_SKIP;
                }
        }


        cb->register_offsets = kcalloc(max, sizeof(int), GFP_KERNEL);
        if (!cb->register_offsets)
                goto err_irq_map;

        of_property_read_u32(node, "ti,reg-size", &size);

        switch (size) {
        case 1:
                cb->write = crossbar_writeb;
                break;
        case 2:
                cb->write = crossbar_writew;
                break;
        case 4:
                cb->write = crossbar_writel;
                break;
        default:
                pr_err("Invalid reg-size property\n");
                ret = -EINVAL;
                goto err_reg_offset;
                break;
        }

        /*
         * Register offsets are not linear because of the
         * reserved irqs. so find and store the offsets once.
         */
        for (i = 0; i < max; i++) {
                if (cb->irq_map[i] == IRQ_RESERVED)
                        continue;

                cb->register_offsets[i] = reserved;
                reserved += size;
        }

        of_property_read_u32(node, "ti,irqs-safe-map", &cb->safe_map);
        /* Initialize the crossbar with safe map to start with */
        for (i = 0; i < max; i++) {
                if (cb->irq_map[i] == IRQ_RESERVED ||
                    cb->irq_map[i] == IRQ_SKIP)
                        continue;

                cb->write(i, cb->safe_map);
        }

        raw_spin_lock_init(&cb->lock);

        return 0;

err_reg_offset:
        kfree(cb->register_offsets);
err_irq_map:
        kfree(cb->irq_map);
err_base:
        iounmap(cb->crossbar_base);
err_cb:
        kfree(cb);

        cb = NULL;
        return ret;
}

static int __init irqcrossbar_init(struct device_node *node,
                                   struct device_node *parent)
{
        struct irq_domain *parent_domain, *domain;
        int err;

        if (!parent) {
                pr_err("%s: no parent, giving up\n", node->full_name);
                return -ENODEV;
        }

        parent_domain = irq_find_host(parent);
        if (!parent_domain) {
                pr_err("%s: unable to obtain parent domain\n", node->full_name);
                return -ENXIO;
        }

        err = crossbar_of_init(node);
        if (err)
                return err;

        domain = irq_domain_add_hierarchy(parent_domain, 0,
                                          cb->max_crossbar_sources,
                                          node, &crossbar_domain_ops,
                                          NULL);
        if (!domain) {
                pr_err("%s: failed to allocated domain\n", node->full_name);
                return -ENOMEM;
        }

        return 0;
}

IRQCHIP_DECLARE(ti_irqcrossbar, "ti,irq-crossbar", irqcrossbar_init);