msi_bitmap.c

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/*
 * Copyright 2006-2008, Michael Ellerman, IBM Corporation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2 of the
 * License.
 *
 */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/bitmap.h>
#include <asm/msi_bitmap.h>
#include <asm/setup.h>

int msi_bitmap_alloc_hwirqs(struct msi_bitmap *bmp, int num)
{
    unsigned long flags;
    int offset, order = get_count_order(num);

    spin_lock_irqsave(&bmp->lock, flags);
    /*
     * This is fast, but stricter than we need. We might want to add
     * a fallback routine which does a linear search with no alignment.
     */
    offset = bitmap_find_free_region(bmp->bitmap, bmp->irq_count, order);
    spin_unlock_irqrestore(&bmp->lock, flags);

    pr_debug("msi_bitmap: allocated 0x%x (2^%d) at offset 0x%x\n",
         num, order, offset);

    return offset;
}

void msi_bitmap_free_hwirqs(struct msi_bitmap *bmp, unsigned int offset,
                unsigned int num)
{
    unsigned long flags;
    int order = get_count_order(num);

    pr_debug("msi_bitmap: freeing 0x%x (2^%d) at offset 0x%x\n",
         num, order, offset);

    spin_lock_irqsave(&bmp->lock, flags);
    bitmap_release_region(bmp->bitmap, offset, order);
    spin_unlock_irqrestore(&bmp->lock, flags);
}

void msi_bitmap_reserve_hwirq(struct msi_bitmap *bmp, unsigned int hwirq)
{
    unsigned long flags;

    pr_debug("msi_bitmap: reserving hwirq 0x%x\n", hwirq);

    spin_lock_irqsave(&bmp->lock, flags);
    bitmap_allocate_region(bmp->bitmap, hwirq, 0);
    spin_unlock_irqrestore(&bmp->lock, flags);
}

int msi_bitmap_reserve_dt_hwirqs(struct msi_bitmap *bmp)
{
    int i, j, len;
    const u32 *p;

    if (!bmp->of_node)
        return 1;

    p = of_get_property(bmp->of_node, "msi-available-ranges", &len);
    if (!p) {
        pr_debug("msi_bitmap: no msi-available-ranges property " \
             "found on %s\n", bmp->of_node->full_name);
        return 1;
    }

    if (len % (2 * sizeof(u32)) != 0) {
        printk(KERN_WARNING "msi_bitmap: Malformed msi-available-ranges"
               " property on %s\n", bmp->of_node->full_name);
        return -EINVAL;
    }

    bitmap_allocate_region(bmp->bitmap, 0, get_count_order(bmp->irq_count));

    spin_lock(&bmp->lock);

    /* Format is: (<u32 start> <u32 count>)+ */
    len /= 2 * sizeof(u32);
    for (i = 0; i < len; i++, p += 2) {
        for (j = 0; j < *(p + 1); j++)
            bitmap_release_region(bmp->bitmap, *p + j, 0);
    }

    spin_unlock(&bmp->lock);

    return 0;
}

int msi_bitmap_alloc(struct msi_bitmap *bmp, unsigned int irq_count,
             struct device_node *of_node)
{
    int size;

    if (!irq_count)
        return -EINVAL;

    size = BITS_TO_LONGS(irq_count) * sizeof(long);
    pr_debug("msi_bitmap: allocator bitmap size is 0x%x bytes\n", size);

    bmp->bitmap = zalloc_maybe_bootmem(size, GFP_KERNEL);
    if (!bmp->bitmap) {
        pr_debug("msi_bitmap: ENOMEM allocating allocator bitmap!\n");
        return -ENOMEM;
    }

    /* We zalloc'ed the bitmap, so all irqs are free by default */
    spin_lock_init(&bmp->lock);
    bmp->of_node = of_node_get(of_node);
    bmp->irq_count = irq_count;

    return 0;
}

void msi_bitmap_free(struct msi_bitmap *bmp)
{
    /* we can't free the bitmap we don't know if it's bootmem etc. */
    of_node_put(bmp->of_node);
    bmp->bitmap = NULL;
}

#ifdef CONFIG_MSI_BITMAP_SELFTEST

#define check(x)    \
    if (!(x)) printk("msi_bitmap: test failed at line %d\n", __LINE__);

void __init test_basics(void)
{
    struct msi_bitmap bmp;
    int i, size = 512;

    /* Can't allocate a bitmap of 0 irqs */
    check(msi_bitmap_alloc(&bmp, 0, NULL) != 0);

    /* of_node may be NULL */
    check(0 == msi_bitmap_alloc(&bmp, size, NULL));

    /* Should all be free by default */
    check(0 == bitmap_find_free_region(bmp.bitmap, size,
                       get_count_order(size)));
    bitmap_release_region(bmp.bitmap, 0, get_count_order(size));

    /* With no node, there's no msi-available-ranges, so expect > 0 */
    check(msi_bitmap_reserve_dt_hwirqs(&bmp) > 0);

    /* Should all still be free */
    check(0 == bitmap_find_free_region(bmp.bitmap, size,
                       get_count_order(size)));
    bitmap_release_region(bmp.bitmap, 0, get_count_order(size));

    /* Check we can fill it up and then no more */
    for (i = 0; i < size; i++)
        check(msi_bitmap_alloc_hwirqs(&bmp, 1) >= 0);

    check(msi_bitmap_alloc_hwirqs(&bmp, 1) < 0);

    /* Should all be allocated */
    check(bitmap_find_free_region(bmp.bitmap, size, 0) < 0);

    /* And if we free one we can then allocate another */
    msi_bitmap_free_hwirqs(&bmp, size / 2, 1);
    check(msi_bitmap_alloc_hwirqs(&bmp, 1) == size / 2);

    msi_bitmap_free(&bmp);

    /* Clients may check bitmap == NULL for "not-allocated" */
    check(bmp.bitmap == NULL);

    kfree(bmp.bitmap);
}

void __init test_of_node(void)
{
    u32 prop_data[] = { 10, 10, 25, 3, 40, 1, 100, 100, 200, 20 };
    const char *expected_str = "0-9,20-24,28-39,41-99,220-255";
    char *prop_name = "msi-available-ranges";
    char *node_name = "/fakenode";
    struct device_node of_node;
    struct property prop;
    struct msi_bitmap bmp;
    int size = 256;
    DECLARE_BITMAP(expected, size);

    /* There should really be a struct device_node allocator */
    memset(&of_node, 0, sizeof(of_node));
    kref_init(&of_node.kref);
    of_node.full_name = node_name;

    check(0 == msi_bitmap_alloc(&bmp, size, &of_node));

    /* No msi-available-ranges, so expect > 0 */
    check(msi_bitmap_reserve_dt_hwirqs(&bmp) > 0);

    /* Should all still be free */
    check(0 == bitmap_find_free_region(bmp.bitmap, size,
                       get_count_order(size)));
    bitmap_release_region(bmp.bitmap, 0, get_count_order(size));

    /* Now create a fake msi-available-ranges property */

    /* There should really .. oh whatever */
    memset(&prop, 0, sizeof(prop));
    prop.name = prop_name;
    prop.value = &prop_data;
    prop.length = sizeof(prop_data);

    of_node.properties = &prop;

    /* msi-available-ranges, so expect == 0 */
    check(msi_bitmap_reserve_dt_hwirqs(&bmp) == 0);

    /* Check we got the expected result */
    check(0 == bitmap_parselist(expected_str, expected, size));
    check(bitmap_equal(expected, bmp.bitmap, size));

    msi_bitmap_free(&bmp);
    kfree(bmp.bitmap);
}

int __init msi_bitmap_selftest(void)
{
    printk(KERN_DEBUG "Running MSI bitmap self-tests ...\n");

    test_basics();
    test_of_node();

    return 0;
}
late_initcall(msi_bitmap_selftest);
#endif /* CONFIG_MSI_BITMAP_SELFTEST */