arch/mips/sgi-ip27/ip27-irqno.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  */
   6 #include <linux/init.h>
   7 #include <linux/irq.h>
   8 #include <linux/types.h>
   9
  10 #include <asm/barrier.h>
  11
  12 static DECLARE_BITMAP(irq_map, NR_IRQS);
  13
  14 int allocate_irqno(void)
  15 {
  16         int irq;
  17
  18 again:
  19         irq = find_first_zero_bit(irq_map, NR_IRQS);
  20
  21         if (irq >= NR_IRQS)
  22                 return -ENOSPC;
  23
  24         if (test_and_set_bit(irq, irq_map))
  25                 goto again;
  26
  27         return irq;
  28 }
  29
  30 /*
  31  * Allocate the 16 legacy interrupts for i8259 devices.  This happens early
  32  * in the kernel initialization so treating allocation failure as BUG() is
  33  * ok.
  34  */
  35 void __init alloc_legacy_irqno(void)
  36 {
  37         int i;
  38
  39         for (i = 0; i <= 16; i++)
  40                 BUG_ON(test_and_set_bit(i, irq_map));
  41 }
  42
  43 void free_irqno(unsigned int irq)
  44 {
  45         smp_mb__before_atomic();
  46         clear_bit(irq, irq_map);
  47         smp_mb__after_atomic();
  48 }