int iosapic_init()

in kernel/iosapic.c [1029:1084]

• 41 lines of code
• 7 McCabe index (conditional complexity)

int iosapic_init(unsigned long phys_addr, unsigned int gsi_base)
{
	int num_rte, err, index;
	unsigned int isa_irq, ver;
	char __iomem *addr;
	unsigned long flags;

	spin_lock_irqsave(&iosapic_lock, flags);
	index = find_iosapic(gsi_base);
	if (index >= 0) {
		spin_unlock_irqrestore(&iosapic_lock, flags);
		return -EBUSY;
	}

	addr = ioremap(phys_addr, 0);
	if (addr == NULL) {
		spin_unlock_irqrestore(&iosapic_lock, flags);
		return -ENOMEM;
	}
	ver = iosapic_version(addr);
	if ((err = iosapic_check_gsi_range(gsi_base, ver))) {
		iounmap(addr);
		spin_unlock_irqrestore(&iosapic_lock, flags);
		return err;
	}

	/*
	 * The MAX_REDIR register holds the highest input pin number
	 * (starting from 0).  We add 1 so that we can use it for
	 * number of pins (= RTEs)
	 */
	num_rte = ((ver >> 16) & 0xff) + 1;

	index = iosapic_alloc();
	iosapic_lists[index].addr = addr;
	iosapic_lists[index].gsi_base = gsi_base;
	iosapic_lists[index].num_rte = num_rte;
#ifdef CONFIG_NUMA
	iosapic_lists[index].node = MAX_NUMNODES;
#endif
	spin_lock_init(&iosapic_lists[index].lock);
	spin_unlock_irqrestore(&iosapic_lock, flags);

	if ((gsi_base == 0) && pcat_compat) {
		/*
		 * Map the legacy ISA devices into the IOSAPIC data.  Some of
		 * these may get reprogrammed later on with data from the ACPI
		 * Interrupt Source Override table.
		 */
		for (isa_irq = 0; isa_irq < 16; ++isa_irq)
			iosapic_override_isa_irq(isa_irq, isa_irq,
						 IOSAPIC_POL_HIGH,
						 IOSAPIC_EDGE);
	}
	return 0;
}