msi.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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.
 */

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

#include <sysdev/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(struct irq_data *data)
{
	pr_debug("mpic_pasemi_msi_mask_irq %d\n", data->irq);
	pci_msi_mask_irq(data);
	mpic_mask_irq(data);
}

static void mpic_pasemi_msi_unmask_irq(struct irq_data *data)
{
	pr_debug("mpic_pasemi_msi_unmask_irq %d\n", data->irq);
	mpic_unmask_irq(data);
	pci_msi_unmask_irq(data);
}

static struct irq_chip mpic_pasemi_msi_chip = {
	.irq_shutdown		= mpic_pasemi_msi_mask_irq,
	.irq_mask		= mpic_pasemi_msi_mask_irq,
	.irq_unmask		= mpic_pasemi_msi_unmask_irq,
	.irq_eoi		= mpic_end_irq,
	.irq_set_type		= mpic_set_irq_type,
	.irq_set_affinity	= mpic_set_affinity,
	.name			= "PASEMI-MSI",
};

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

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

	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
		hwirq = virq_to_hw(entry->irq);
		irq_set_msi_desc(entry->irq, NULL);
		irq_dispose_mapping(entry->irq);
		entry->irq = 0;
		msi_bitmap_free_hwirqs(&msi_mpic->msi_bitmap, hwirq, ALLOC_CHUNK);
	}
}

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;

	if (type == PCI_CAP_ID_MSIX)
		pr_debug("pasemi_msi: MSI-X untested, trying anyway\n");
	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;

	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_NOTASSOCIATED) {
		/* 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) {
			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);

		irq_set_msi_desc(virq, entry);
		irq_set_chip(virq, &mpic_pasemi_msi_chip);
		irq_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;
		pci_write_msi_msg(virq, &msg);
	}

	return 0;
}

int __init mpic_pasemi_msi_init(struct mpic *mpic)
{
	int rc;
	struct pci_controller *phb;
	struct device_node *of_node;

	of_node = irq_domain_get_of_node(mpic->irqhost);
	if (!of_node ||
	    !of_device_is_compatible(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;
	list_for_each_entry(phb, &hose_list, list_node) {
		WARN_ON(phb->controller_ops.setup_msi_irqs);
		phb->controller_ops.setup_msi_irqs = pasemi_msi_setup_msi_irqs;
		phb->controller_ops.teardown_msi_irqs = pasemi_msi_teardown_msi_irqs;
	}

	return 0;
}