imask.c

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/*
 * arch/sh/kernel/cpu/irq/imask.c
 *
 * Copyright (C) 1999, 2000  Niibe Yutaka
 *
 * Simple interrupt handling using IMASK of SR register.
 *
 */
/* NOTE: Will not work on level 15 */
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/irq.h>
#include <linux/bitmap.h>
#include <asm/irq.h>

/* Bitmap of IRQ masked */
#define IMASK_PRIORITY  15

static DECLARE_BITMAP(imask_mask, IMASK_PRIORITY);
static int interrupt_priority;

static inline void set_interrupt_registers(int ip)
{
    unsigned long __dummy;

    asm volatile(
#ifdef CONFIG_CPU_HAS_SR_RB
             "ldc   %2, r6_bank\n\t"
#endif
             "stc   sr, %0\n\t"
             "and   #0xf0, %0\n\t"
             "shlr2 %0\n\t"
             "cmp/eq    #0x3c, %0\n\t"
             "bt/s  1f  ! CLI-ed\n\t"
             " stc  sr, %0\n\t"
             "and   %1, %0\n\t"
             "or    %2, %0\n\t"
             "ldc   %0, sr\n"
             "1:"
             : "=&z" (__dummy)
             : "r" (~0xf0), "r" (ip << 4)
             : "t");
}

static void mask_imask_irq(struct irq_data *data)
{
    unsigned int irq = data->irq;

    clear_bit(irq, imask_mask);
    if (interrupt_priority < IMASK_PRIORITY - irq)
        interrupt_priority = IMASK_PRIORITY - irq;
    set_interrupt_registers(interrupt_priority);
}

static void unmask_imask_irq(struct irq_data *data)
{
    unsigned int irq = data->irq;

    set_bit(irq, imask_mask);
    interrupt_priority = IMASK_PRIORITY -
        find_first_zero_bit(imask_mask, IMASK_PRIORITY);
    set_interrupt_registers(interrupt_priority);
}

static struct irq_chip imask_irq_chip = {
    .name       = "SR.IMASK",
    .irq_mask   = mask_imask_irq,
    .irq_unmask = unmask_imask_irq,
    .irq_mask_ack   = mask_imask_irq,
};

void make_imask_irq(unsigned int irq)
{
    irq_set_chip_and_handler_name(irq, &imask_irq_chip, handle_level_irq,
                      "level");
}