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irq-mb93093.c

/* irq-mb93093.c: MB93093 FPGA interrupt handling
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/bitops.h>

#include <asm/io.h>
#include <asm/system.h>
#include <asm/delay.h>
#include <asm/irq.h>
#include <asm/irc-regs.h>

#define __reg16(ADDR) (*(volatile unsigned short *)(__region_CS2 + (ADDR)))

#define __get_IMR()     ({ __reg16(0x0a); })
#define __set_IMR(M)    do { __reg16(0x0a) = (M);  wmb(); } while(0)
#define __get_IFR()     ({ __reg16(0x02); })
#define __clr_IFR(M)    do { __reg16(0x02) = ~(M); wmb(); } while(0)

/*
 * off-CPU FPGA PIC operations
 */
static void frv_fpga_mask(unsigned int irq)
{
      uint16_t imr = __get_IMR();

      imr |= 1 << (irq - IRQ_BASE_FPGA);
      __set_IMR(imr);
}

static void frv_fpga_ack(unsigned int irq)
{
      __clr_IFR(1 << (irq - IRQ_BASE_FPGA));
}

static void frv_fpga_mask_ack(unsigned int irq)
{
      uint16_t imr = __get_IMR();

      imr |= 1 << (irq - IRQ_BASE_FPGA);
      __set_IMR(imr);

      __clr_IFR(1 << (irq - IRQ_BASE_FPGA));
}

static void frv_fpga_unmask(unsigned int irq)
{
      uint16_t imr = __get_IMR();

      imr &= ~(1 << (irq - IRQ_BASE_FPGA));

      __set_IMR(imr);
}

static struct irq_chip frv_fpga_pic = {
      .name       = "mb93093",
      .ack        = frv_fpga_ack,
      .mask       = frv_fpga_mask,
      .mask_ack   = frv_fpga_mask_ack,
      .unmask           = frv_fpga_unmask,
      .end        = frv_fpga_end,
};

/*
 * FPGA PIC interrupt handler
 */
static irqreturn_t fpga_interrupt(int irq, void *_mask)
{
      uint16_t imr, mask = (unsigned long) _mask;

      imr = __get_IMR();
      mask = mask & ~imr & __get_IFR();

      /* poll all the triggered IRQs */
      while (mask) {
            int irq;

            asm("scan %1,gr0,%0" : "=r"(irq) : "r"(mask));
            irq = 31 - irq;
            mask &= ~(1 << irq);

            generic_irq_handle(IRQ_BASE_FPGA + irq);
      }

      return IRQ_HANDLED;
}

/*
 * define an interrupt action for each FPGA PIC output
 * - use dev_id to indicate the FPGA PIC input to output mappings
 */
static struct irqaction fpga_irq[1]  = {
      [0] = {
            .handler    = fpga_interrupt,
            .flags            = IRQF_DISABLED,
            .name       = "fpga.0",
            .dev_id           = (void *) 0x0700UL,
      }
};

/*
 * initialise the motherboard FPGA's PIC
 */
void __init fpga_init(void)
{
      int irq;

      /* all PIC inputs are all set to be edge triggered */
      __set_IMR(0x0700);
      __clr_IFR(0x0000);

      for (irq = IRQ_BASE_FPGA + 8; irq <= IRQ_BASE_FPGA + 10; irq++)
            set_irq_chip_and_handler(irq, &frv_fpga_pic, handle_edge_irq);

      /* the FPGA drives external IRQ input #2 on the CPU PIC */
      setup_irq(IRQ_CPU_EXTERNAL2, &fpga_irq[0]);
}

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