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interrupt.c

/*
 * Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
 *
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Routines for generic manipulation of the interrupts found on the
 * Lasat boards.
 */
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

#include <asm/irq_cpu.h>
#include <asm/lasat/lasat.h>
#include <asm/lasat/lasatint.h>

#include <irq.h>

static volatile int *lasat_int_status;
static volatile int *lasat_int_mask;
static volatile int lasat_int_mask_shift;

void disable_lasat_irq(unsigned int irq_nr)
{
      irq_nr -= LASAT_IRQ_BASE;
      *lasat_int_mask &= ~(1 << irq_nr) << lasat_int_mask_shift;
}

void enable_lasat_irq(unsigned int irq_nr)
{
      irq_nr -= LASAT_IRQ_BASE;
      *lasat_int_mask |= (1 << irq_nr) << lasat_int_mask_shift;
}

static struct irq_chip lasat_irq_type = {
      .name = "Lasat",
      .ack = disable_lasat_irq,
      .mask = disable_lasat_irq,
      .mask_ack = disable_lasat_irq,
      .unmask = enable_lasat_irq,
};

static inline int ls1bit32(unsigned int x)
{
      int b = 31, s;

      s = 16; if (x << 16 == 0) s = 0; b -= s; x <<= s;
      s =  8; if (x <<  8 == 0) s = 0; b -= s; x <<= s;
      s =  4; if (x <<  4 == 0) s = 0; b -= s; x <<= s;
      s =  2; if (x <<  2 == 0) s = 0; b -= s; x <<= s;
      s =  1; if (x <<  1 == 0) s = 0; b -= s;

      return b;
}

static unsigned long (*get_int_status)(void);

static unsigned long get_int_status_100(void)
{
      return *lasat_int_status & *lasat_int_mask;
}

static unsigned long get_int_status_200(void)
{
      unsigned long int_status;

      int_status = *lasat_int_status;
      int_status &= (int_status >> LASATINT_MASK_SHIFT_200) & 0xffff;
      return int_status;
}

asmlinkage void plat_irq_dispatch(void)
{
      unsigned long int_status;
      unsigned int cause = read_c0_cause();
      int irq;

      if (cause & CAUSEF_IP7) {     /* R4000 count / compare IRQ */
            do_IRQ(7);
            return;
      }

      int_status = get_int_status();

      /* if int_status == 0, then the interrupt has already been cleared */
      if (int_status) {
            irq = LASAT_IRQ_BASE + ls1bit32(int_status);

            do_IRQ(irq);
      }
}

static struct irqaction cascade = {
      .handler    = no_action,
      .mask       = CPU_MASK_NONE,
      .name       = "cascade",
};

void __init arch_init_irq(void)
{
      int i;

      if (IS_LASAT_200()) {
            lasat_int_status = (void *)LASAT_INT_STATUS_REG_200;
            lasat_int_mask = (void *)LASAT_INT_MASK_REG_200;
            lasat_int_mask_shift = LASATINT_MASK_SHIFT_200;
            get_int_status = get_int_status_200;
            *lasat_int_mask &= 0xffff;
      } else {
            lasat_int_status = (void *)LASAT_INT_STATUS_REG_100;
            lasat_int_mask = (void *)LASAT_INT_MASK_REG_100;
            lasat_int_mask_shift = LASATINT_MASK_SHIFT_100;
            get_int_status = get_int_status_100;
            *lasat_int_mask = 0;
      }

      mips_cpu_irq_init();

      for (i = LASAT_IRQ_BASE; i <= LASAT_IRQ_END; i++)
            set_irq_chip_and_handler(i, &lasat_irq_type, handle_level_irq);

      setup_irq(LASAT_CASCADE_IRQ, &cascade);
}

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