static irqreturn_t eisa_irq()

in eisa.c [190:238]

• 37 lines of code
• 3 McCabe index (conditional complexity)

static irqreturn_t eisa_irq(int wax_irq, void *intr_dev)
{
	int irq = gsc_readb(0xfc01f000); /* EISA supports 16 irqs */
	unsigned long flags;

	spin_lock_irqsave(&eisa_irq_lock, flags);
	/* read IRR command */
	eisa_out8(0x0a, 0x20);
	eisa_out8(0x0a, 0xa0);

	EISA_DBG("irq IAR %02x 8259-1 irr %02x 8259-2 irr %02x\n",
		   irq, eisa_in8(0x20), eisa_in8(0xa0));

	/* read ISR command */
	eisa_out8(0x0a, 0x20);
	eisa_out8(0x0a, 0xa0);
	EISA_DBG("irq 8259-1 isr %02x imr %02x 8259-2 isr %02x imr %02x\n",
		 eisa_in8(0x20), eisa_in8(0x21), eisa_in8(0xa0), eisa_in8(0xa1));

	irq &= 0xf;

	/* mask irq and write eoi */
	if (irq & 8) {
		slave_mask |= (1 << (irq&7));
		eisa_out8(slave_mask, 0xa1);
		eisa_out8(0x60 | (irq&7),0xa0);/* 'Specific EOI' to slave */
		eisa_out8(0x62, 0x20);	/* 'Specific EOI' to master-IRQ2 */

	} else {
		master_mask |= (1 << (irq&7));
		eisa_out8(master_mask, 0x21);
		eisa_out8(0x60|irq, 0x20);	/* 'Specific EOI' to master */
	}
	spin_unlock_irqrestore(&eisa_irq_lock, flags);

	generic_handle_irq(irq);

	spin_lock_irqsave(&eisa_irq_lock, flags);
	/* unmask */
        if (irq & 8) {
		slave_mask &= ~(1 << (irq&7));
		eisa_out8(slave_mask, 0xa1);
	} else {
		master_mask &= ~(1 << (irq&7));
		eisa_out8(master_mask, 0x21);
	}
	spin_unlock_irqrestore(&eisa_irq_lock, flags);
	return IRQ_HANDLED;
}