virq.c

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/*
 * Support for virtual IRQ subgroups.
 *
 * Copyright (C) 2010  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#define pr_fmt(fmt) "intc: " fmt

#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/list.h>
#include <linux/radix-tree.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include "internals.h"

static struct intc_map_entry intc_irq_xlate[INTC_NR_IRQS];

struct intc_virq_list {
    unsigned int irq;
    struct intc_virq_list *next;
};

#define for_each_virq(entry, head) \
    for (entry = head; entry; entry = entry->next)

/*
 * Tags for the radix tree
 */
#define INTC_TAG_VIRQ_NEEDS_ALLOC   0

void intc_irq_xlate_set(unsigned int irq, intc_enum id, struct intc_desc_int *d)
{
    unsigned long flags;

    raw_spin_lock_irqsave(&intc_big_lock, flags);
    intc_irq_xlate[irq].enum_id = id;
    intc_irq_xlate[irq].desc = d;
    raw_spin_unlock_irqrestore(&intc_big_lock, flags);
}

struct intc_map_entry *intc_irq_xlate_get(unsigned int irq)
{
    return intc_irq_xlate + irq;
}

int intc_irq_lookup(const char *chipname, intc_enum enum_id)
{
    struct intc_map_entry *ptr;
    struct intc_desc_int *d;
    int irq = -1;

    list_for_each_entry(d, &intc_list, list) {
        int tagged;

        if (strcmp(d->chip.name, chipname) != 0)
            continue;

        /*
         * Catch early lookups for subgroup VIRQs that have not
         * yet been allocated an IRQ. This already includes a
         * fast-path out if the tree is untagged, so there is no
         * need to explicitly test the root tree.
         */
        tagged = radix_tree_tag_get(&d->tree, enum_id,
                        INTC_TAG_VIRQ_NEEDS_ALLOC);
        if (unlikely(tagged))
            break;

        ptr = radix_tree_lookup(&d->tree, enum_id);
        if (ptr) {
            irq = ptr - intc_irq_xlate;
            break;
        }
    }

    return irq;
}
EXPORT_SYMBOL_GPL(intc_irq_lookup);

static int add_virq_to_pirq(unsigned int irq, unsigned int virq)
{
    struct intc_virq_list **last, *entry;
    struct irq_data *data = irq_get_irq_data(irq);

    /* scan for duplicates */
    last = (struct intc_virq_list **)&data->handler_data;
    for_each_virq(entry, data->handler_data) {
        if (entry->irq == virq)
            return 0;
        last = &entry->next;
    }

    entry = kzalloc(sizeof(struct intc_virq_list), GFP_ATOMIC);
    if (!entry) {
        pr_err("can't allocate VIRQ mapping for %d\n", virq);
        return -ENOMEM;
    }

    entry->irq = virq;

    *last = entry;

    return 0;
}

static void intc_virq_handler(unsigned int irq, struct irq_desc *desc)
{
    struct irq_data *data = irq_get_irq_data(irq);
    struct irq_chip *chip = irq_data_get_irq_chip(data);
    struct intc_virq_list *entry, *vlist = irq_data_get_irq_handler_data(data);
    struct intc_desc_int *d = get_intc_desc(irq);

    chip->irq_mask_ack(data);

    for_each_virq(entry, vlist) {
        unsigned long addr, handle;

        handle = (unsigned long)irq_get_handler_data(entry->irq);
        addr = INTC_REG(d, _INTC_ADDR_E(handle), 0);

        if (intc_reg_fns[_INTC_FN(handle)](addr, handle, 0))
            generic_handle_irq(entry->irq);
    }

    chip->irq_unmask(data);
}

static unsigned long __init intc_subgroup_data(struct intc_subgroup *subgroup,
                           struct intc_desc_int *d,
                           unsigned int index)
{
    unsigned int fn = REG_FN_TEST_BASE + (subgroup->reg_width >> 3) - 1;

    return _INTC_MK(fn, MODE_ENABLE_REG, intc_get_reg(d, subgroup->reg),
            0, 1, (subgroup->reg_width - 1) - index);
}

static void __init intc_subgroup_init_one(struct intc_desc *desc,
                      struct intc_desc_int *d,
                      struct intc_subgroup *subgroup)
{
    struct intc_map_entry *mapped;
    unsigned int pirq;
    unsigned long flags;
    int i;

    mapped = radix_tree_lookup(&d->tree, subgroup->parent_id);
    if (!mapped) {
        WARN_ON(1);
        return;
    }

    pirq = mapped - intc_irq_xlate;

    raw_spin_lock_irqsave(&d->lock, flags);

    for (i = 0; i < ARRAY_SIZE(subgroup->enum_ids); i++) {
        struct intc_subgroup_entry *entry;
        int err;

        if (!subgroup->enum_ids[i])
            continue;

        entry = kmalloc(sizeof(*entry), GFP_NOWAIT);
        if (!entry)
            break;

        entry->pirq = pirq;
        entry->enum_id = subgroup->enum_ids[i];
        entry->handle = intc_subgroup_data(subgroup, d, i);

        err = radix_tree_insert(&d->tree, entry->enum_id, entry);
        if (unlikely(err < 0))
            break;

        radix_tree_tag_set(&d->tree, entry->enum_id,
                   INTC_TAG_VIRQ_NEEDS_ALLOC);
    }

    raw_spin_unlock_irqrestore(&d->lock, flags);
}

void __init intc_subgroup_init(struct intc_desc *desc, struct intc_desc_int *d)
{
    int i;

    if (!desc->hw.subgroups)
        return;

    for (i = 0; i < desc->hw.nr_subgroups; i++)
        intc_subgroup_init_one(desc, d, desc->hw.subgroups + i);
}

static void __init intc_subgroup_map(struct intc_desc_int *d)
{
    struct intc_subgroup_entry *entries[32];
    unsigned long flags;
    unsigned int nr_found;
    int i;

    raw_spin_lock_irqsave(&d->lock, flags);

restart:
    nr_found = radix_tree_gang_lookup_tag_slot(&d->tree,
            (void ***)entries, 0, ARRAY_SIZE(entries),
            INTC_TAG_VIRQ_NEEDS_ALLOC);

    for (i = 0; i < nr_found; i++) {
        struct intc_subgroup_entry *entry;
        int irq;

        entry = radix_tree_deref_slot((void **)entries[i]);
        if (unlikely(!entry))
            continue;
        if (radix_tree_deref_retry(entry))
            goto restart;

        irq = irq_alloc_desc(numa_node_id());
        if (unlikely(irq < 0)) {
            pr_err("no more free IRQs, bailing..\n");
            break;
        }

        activate_irq(irq);

        pr_info("Setting up a chained VIRQ from %d -> %d\n",
            irq, entry->pirq);

        intc_irq_xlate_set(irq, entry->enum_id, d);

        irq_set_chip_and_handler_name(irq, irq_get_chip(entry->pirq),
                          handle_simple_irq, "virq");
        irq_set_chip_data(irq, irq_get_chip_data(entry->pirq));

        irq_set_handler_data(irq, (void *)entry->handle);

        /*
         * Set the virtual IRQ as non-threadable.
         */
        irq_set_nothread(irq);

        irq_set_chained_handler(entry->pirq, intc_virq_handler);
        add_virq_to_pirq(entry->pirq, irq);

        radix_tree_tag_clear(&d->tree, entry->enum_id,
                     INTC_TAG_VIRQ_NEEDS_ALLOC);
        radix_tree_replace_slot((void **)entries[i],
                    &intc_irq_xlate[irq]);
    }

    raw_spin_unlock_irqrestore(&d->lock, flags);
}

void __init intc_finalize(void)
{
    struct intc_desc_int *d;

    list_for_each_entry(d, &intc_list, list)
        if (radix_tree_tagged(&d->tree, INTC_TAG_VIRQ_NEEDS_ALLOC))
            intc_subgroup_map(d);
}