/*
 * Copyright 2007, Olof Johansson, PA Semi
 *
 * Based on arch/powerpc/sysdev/mpic_u3msi.c:
 *
 * Copyright 2006, Segher Boessenkool, IBM Corporation.
 * Copyright 2006-2007, Michael Ellerman, IBM Corporation.
 *
 * 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; version 2 of the
 * License.
 *
 */

#undef DEBUG

#include <linux/irq.h>
#include <linux/bootmem.h>
#include <linux/msi.h>
#include <asm/mpic.h>
#include <asm/prom.h>
#include <asm/hw_irq.h>
#include <asm/ppc-pci.h>
#include <asm/msi_bitmap.h>

#include "mpic.h"

/* Allocate 16 interrupts per device, to give an alignment of 16,
 * since that's the size of the grouping w.r.t. affinity. If someone
 * needs more than 32 MSI's down the road we'll have to rethink this,
 * but it should be OK for now.
 */
#define ALLOC_CHUNK 16

#define PASEMI_MSI_ADDR 0xfc080000

/* A bit ugly, can we get this from the pci_dev somehow? */
static struct mpic *msi_mpic;


static void mpic_pasemi_msi_mask_irq(unsigned int irq)
{
	pr_debug("mpic_pasemi_msi_mask_irq %d\n", irq);
	mask_msi_irq(irq);
	mpic_mask_irq(irq);
}

static void mpic_pasemi_msi_unmask_irq(unsigned int irq)
{
	pr_debug("mpic_pasemi_msi_unmask_irq %d\n", irq);
	mpic_unmask_irq(irq);
	unmask_msi_irq(irq);
}

static struct irq_chip mpic_pasemi_msi_chip = {
	.shutdown	= mpic_pasemi_msi_mask_irq,
	.mask		= mpic_pasemi_msi_mask_irq,
	.unmask		= mpic_pasemi_msi_unmask_irq,
	.eoi		= mpic_end_irq,
	.set_type	= mpic_set_irq_type,
	.set_affinity	= mpic_set_affinity,
	.name		= "PASEMI-MSI",
};

static int pasemi_msi_check_device(struct pci_dev *pdev, int nvec, int type)
{
	if (type == PCI_CAP_ID_MSIX)
		pr_debug("pasemi_msi: MSI-X untested, trying anyway\n");

	return 0;
}

static void pasemi_msi_teardown_msi_irqs(struct pci_dev *pdev)
{
	struct msi_desc *entry;

	pr_debug("pasemi_msi_teardown_msi_irqs, pdev %p\n", pdev);

	list_for_each_entry(entry, &pdev->msi_list, list) {
		if (entry->irq == NO_IRQ)
			continue;

		set_irq_msi(entry->irq, NULL);
		msi_bitmap_free_hwirqs(&msi_mpic->msi_bitmap,
				       virq_to_hw(entry->irq), ALLOC_CHUNK);
		irq_dispose_mapping(entry->irq);
	}

	return;
}

static int pasemi_msi_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
{
	unsigned int virq;
	struct msi_desc *entry;
	struct msi_msg msg;
	int hwirq;

	pr_debug("pasemi_msi_setup_msi_irqs, pdev %p nvec %d type %d\n",
		 pdev, nvec, type);

	msg.address_hi = 0;
	msg.address_lo = PASEMI_MSI_ADDR;

	list_for_each_entry(entry, &pdev->msi_list, list) {
		/* Allocate 16 interrupts for now, since that's the grouping for
		 * affinity. This can be changed later if it turns out 32 is too
		 * few MSIs for someone, but restrictions will apply to how the
		 * sources can be changed independently.
		 */
		hwirq = msi_bitmap_alloc_hwirqs(&msi_mpic->msi_bitmap,
						ALLOC_CHUNK);
		if (hwirq < 0) {
			pr_debug("pasemi_msi: failed allocating hwirq\n");
			return hwirq;
		}

		virq = irq_create_mapping(msi_mpic->irqhost, hwirq);
		if (virq == NO_IRQ) {
			pr_debug("pasemi_msi: failed mapping hwirq 0x%x\n",
				  hwirq);
			msi_bitmap_free_hwirqs(&msi_mpic->msi_bitmap, hwirq,
					       ALLOC_CHUNK);
			return -ENOSPC;
		}

		/* Vector on MSI is really an offset, the hardware adds
		 * it to the value written at the magic address. So set
		 * it to 0 to remain sane.
		 */
		mpic_set_vector(virq, 0);

		set_irq_msi(virq, entry);
		set_irq_chip(virq, &mpic_pasemi_msi_chip);
		set_irq_type(virq, IRQ_TYPE_EDGE_RISING);

		pr_debug("pasemi_msi: allocated virq 0x%x (hw 0x%x) " \
			 "addr 0x%x\n", virq, hwirq, msg.address_lo);

		/* Likewise, the device writes [0...511] into the target
		 * register to generate MSI [512...1023]
		 */
		msg.data = hwirq-0x200;
		write_msi_msg(virq, &msg);
	}

	return 0;
}

int mpic_pasemi_msi_init(struct mpic *mpic)
{
	int rc;

	if (!mpic->irqhost->of_node ||
	    !of_device_is_compatible(mpic->irqhost->of_node,
				     "pasemi,pwrficient-openpic"))
		return -ENODEV;

	rc = mpic_msi_init_allocator(mpic);
	if (rc) {
		pr_debug("pasemi_msi: Error allocating bitmap!\n");
		return rc;
	}

	pr_debug("pasemi_msi: Registering PA Semi MPIC MSI callbacks\n");

	msi_mpic = mpic;
	WARN_ON(ppc_md.setup_msi_irqs);
	ppc_md.setup_msi_irqs = pasemi_msi_setup_msi_irqs;
	ppc_md.teardown_msi_irqs = pasemi_msi_teardown_msi_irqs;
	ppc_md.msi_check_device = pasemi_msi_check_device;

	return 0;
}