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mpic_msi.c

/*
 * Copyright 2006-2007, 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/irq.h>
#include <linux/bitmap.h>
#include <linux/msi.h>
#include <asm/mpic.h>
#include <asm/prom.h>
#include <asm/hw_irq.h>
#include <asm/ppc-pci.h>

#include <sysdev/mpic.h>

static void __mpic_msi_reserve_hwirq(struct mpic *mpic, irq_hw_number_t hwirq)
{
      pr_debug("mpic: reserving hwirq 0x%lx\n", hwirq);
      bitmap_allocate_region(mpic->hwirq_bitmap, hwirq, 0);
}

void mpic_msi_reserve_hwirq(struct mpic *mpic, irq_hw_number_t hwirq)
{
      unsigned long flags;

      /* The mpic calls this even when there is no allocator setup */
      if (!mpic->hwirq_bitmap)
            return;

      spin_lock_irqsave(&mpic->bitmap_lock, flags);
      __mpic_msi_reserve_hwirq(mpic, hwirq);
      spin_unlock_irqrestore(&mpic->bitmap_lock, flags);
}

irq_hw_number_t mpic_msi_alloc_hwirqs(struct mpic *mpic, int num)
{
      unsigned long flags;
      int offset, order = get_count_order(num);

      spin_lock_irqsave(&mpic->bitmap_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(mpic->hwirq_bitmap, mpic->irq_count,
                               order);
      spin_unlock_irqrestore(&mpic->bitmap_lock, flags);

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

      return offset;
}

void mpic_msi_free_hwirqs(struct mpic *mpic, int offset, int num)
{
      unsigned long flags;
      int order = get_count_order(num);

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

      spin_lock_irqsave(&mpic->bitmap_lock, flags);
      bitmap_release_region(mpic->hwirq_bitmap, offset, order);
      spin_unlock_irqrestore(&mpic->bitmap_lock, flags);
}

#ifdef CONFIG_MPIC_U3_HT_IRQS
static int mpic_msi_reserve_u3_hwirqs(struct mpic *mpic)
{
      irq_hw_number_t hwirq;
      struct irq_host_ops *ops = mpic->irqhost->ops;
      struct device_node *np;
      int flags, index, i;
      struct of_irq oirq;

      pr_debug("mpic: found U3, guessing msi allocator setup\n");

      /* Reserve source numbers we know are reserved in the HW */
      for (i = 0;   i < 8;   i++)
            __mpic_msi_reserve_hwirq(mpic, i);

      for (i = 42;  i < 46;  i++)
            __mpic_msi_reserve_hwirq(mpic, i);

      for (i = 100; i < 105; i++)
            __mpic_msi_reserve_hwirq(mpic, i);

      np = NULL;
      while ((np = of_find_all_nodes(np))) {
            pr_debug("mpic: mapping hwirqs for %s\n", np->full_name);

            index = 0;
            while (of_irq_map_one(np, index++, &oirq) == 0) {
                  ops->xlate(mpic->irqhost, NULL, oirq.specifier,
                                    oirq.size, &hwirq, &flags);
                  __mpic_msi_reserve_hwirq(mpic, hwirq);
            }
      }

      return 0;
}
#else
static int mpic_msi_reserve_u3_hwirqs(struct mpic *mpic)
{
      return -1;
}
#endif

static int mpic_msi_reserve_dt_hwirqs(struct mpic *mpic)
{
      int i, len;
      const u32 *p;

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

      if (len % 8 != 0) {
            printk(KERN_WARNING "mpic: Malformed msi-available-ranges "
                   "property on %s\n", mpic->irqhost->of_node->full_name);
            return -EINVAL;
      }

      bitmap_allocate_region(mpic->hwirq_bitmap, 0,
                         get_count_order(mpic->irq_count));

      /* Format is: (<u32 start> <u32 count>)+ */
      len /= sizeof(u32);
      for (i = 0; i < len / 2; i++, p += 2)
            mpic_msi_free_hwirqs(mpic, *p, *(p + 1));

      return 0;
}

int mpic_msi_init_allocator(struct mpic *mpic)
{
      int rc, size;

      BUG_ON(mpic->hwirq_bitmap);
      spin_lock_init(&mpic->bitmap_lock);

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

      mpic->hwirq_bitmap = alloc_maybe_bootmem(size, GFP_KERNEL);

      if (!mpic->hwirq_bitmap) {
            pr_debug("mpic: ENOMEM allocating allocator bitmap!\n");
            return -ENOMEM;
      }

      memset(mpic->hwirq_bitmap, 0, size);

      rc = mpic_msi_reserve_dt_hwirqs(mpic);
      if (rc) {
            if (mpic->flags & MPIC_U3_HT_IRQS)
                  rc = mpic_msi_reserve_u3_hwirqs(mpic);

            if (rc)
                  goto out_free;
      }

      return 0;

 out_free:
      if (mem_init_done)
            kfree(mpic->hwirq_bitmap);

      mpic->hwirq_bitmap = NULL;
      return rc;
}

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