/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * SGI UV IRQ functions
 *
 * Copyright (C) 2008 Silicon Graphics, Inc. All rights reserved.
 */

#include <linux/module.h>
#include <linux/rbtree.h>
#include <linux/irq.h>

#include <asm/apic.h>
#include <asm/uv/uv_irq.h>
#include <asm/uv/uv_hub.h>

/* MMR offset and pnode of hub sourcing interrupts for a given irq */
struct uv_irq_2_mmr_pnode{
	struct rb_node list;
	unsigned long offset;
	int pnode;
	int irq;
};
static spinlock_t uv_irq_lock;
static struct rb_root uv_irq_root;

static void uv_noop(unsigned int irq)
{
}

static unsigned int uv_noop_ret(unsigned int irq)
{
	return 0;
}

static void uv_ack_apic(unsigned int irq)
{
	ack_APIC_irq();
}

struct irq_chip uv_irq_chip = {
	.name		= "UV-CORE",
	.startup	= uv_noop_ret,
	.shutdown	= uv_noop,
	.enable		= uv_noop,
	.disable	= uv_noop,
	.ack		= uv_noop,
	.mask		= uv_noop,
	.unmask		= uv_noop,
	.eoi		= uv_ack_apic,
	.end		= uv_noop,
	.set_affinity	= uv_set_irq_affinity,
};

/*
 * Add offset and pnode information of the hub sourcing interrupts to the
 * rb tree for a specific irq.
 */
static int uv_set_irq_2_mmr_info(int irq, unsigned long offset, unsigned blade)
{
	struct rb_node **link = &uv_irq_root.rb_node;
	struct rb_node *parent = NULL;
	struct uv_irq_2_mmr_pnode *n;
	struct uv_irq_2_mmr_pnode *e;
	unsigned long irqflags;

	n = kmalloc_node(sizeof(struct uv_irq_2_mmr_pnode), GFP_KERNEL,
				uv_blade_to_memory_nid(blade));
	if (!n)
		return -ENOMEM;

	n->irq = irq;
	n->offset = offset;
	n->pnode = uv_blade_to_pnode(blade);
	spin_lock_irqsave(&uv_irq_lock, irqflags);
	/* Find the right place in the rbtree: */
	while (*link) {
		parent = *link;
		e = rb_entry(parent, struct uv_irq_2_mmr_pnode, list);

		if (unlikely(irq == e->irq)) {
			/* irq entry exists */
			e->pnode = uv_blade_to_pnode(blade);
			e->offset = offset;
			spin_unlock_irqrestore(&uv_irq_lock, irqflags);
			kfree(n);
			return 0;
		}

		if (irq < e->irq)
			link = &(*link)->rb_left;
		else
			link = &(*link)->rb_right;
	}

	/* Insert the node into the rbtree. */
	rb_link_node(&n->list, parent, link);
	rb_insert_color(&n->list, &uv_irq_root);

	spin_unlock_irqrestore(&uv_irq_lock, irqflags);
	return 0;
}

/* Retrieve offset and pnode information from the rb tree for a specific irq */
int uv_irq_2_mmr_info(int irq, unsigned long *offset, int *pnode)
{
	struct uv_irq_2_mmr_pnode *e;
	struct rb_node *n;
	unsigned long irqflags;

	spin_lock_irqsave(&uv_irq_lock, irqflags);
	n = uv_irq_root.rb_node;
	while (n) {
		e = rb_entry(n, struct uv_irq_2_mmr_pnode, list);

		if (e->irq == irq) {
			*offset = e->offset;
			*pnode = e->pnode;
			spin_unlock_irqrestore(&uv_irq_lock, irqflags);
			return 0;
		}

		if (irq < e->irq)
			n = n->rb_left;
		else
			n = n->rb_right;
	}
	spin_unlock_irqrestore(&uv_irq_lock, irqflags);
	return -1;
}

/*
 * Set up a mapping of an available irq and vector, and enable the specified
 * MMR that defines the MSI that is to be sent to the specified CPU when an
 * interrupt is raised.
 */
int uv_setup_irq(char *irq_name, int cpu, int mmr_blade,
		 unsigned long mmr_offset, int restrict)
{
	int irq, ret;

	irq = create_irq_nr(NR_IRQS_LEGACY, uv_blade_to_memory_nid(mmr_blade));

	if (irq <= 0)
		return -EBUSY;

	ret = arch_enable_uv_irq(irq_name, irq, cpu, mmr_blade, mmr_offset,
		restrict);
	if (ret == irq)
		uv_set_irq_2_mmr_info(irq, mmr_offset, mmr_blade);
	else
		destroy_irq(irq);

	return ret;
}
EXPORT_SYMBOL_GPL(uv_setup_irq);

/*
 * Tear down a mapping of an irq and vector, and disable the specified MMR that
 * defined the MSI that was to be sent to the specified CPU when an interrupt
 * was raised.
 *
 * Set mmr_blade and mmr_offset to what was passed in on uv_setup_irq().
 */
void uv_teardown_irq(unsigned int irq)
{
	struct uv_irq_2_mmr_pnode *e;
	struct rb_node *n;
	unsigned long irqflags;

	spin_lock_irqsave(&uv_irq_lock, irqflags);
	n = uv_irq_root.rb_node;
	while (n) {
		e = rb_entry(n, struct uv_irq_2_mmr_pnode, list);
		if (e->irq == irq) {
			arch_disable_uv_irq(e->pnode, e->offset);
			rb_erase(n, &uv_irq_root);
			kfree(e);
			break;
		}
		if (irq < e->irq)
			n = n->rb_left;
		else
			n = n->rb_right;
	}
	spin_unlock_irqrestore(&uv_irq_lock, irqflags);
	destroy_irq(irq);
}
EXPORT_SYMBOL_GPL(uv_teardown_irq);