/*
 * Annapurna Labs MSIX support services
 *
 * Copyright (C) 2016, Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Antoine Tenart <antoine.tenart@free-electrons.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/irqchip.h>
#include <linux/irqchip/arm-gic.h>
#include <linux/irqchip/irq-msi-lib.h>
#include <linux/msi.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_pci.h>
#include <linux/pci.h>
#include <linux/slab.h>

#include <asm/irq.h>
#include <asm/msi.h>

/* MSIX message address format: local GIC target */
#define ALPINE_MSIX_SPI_TARGET_CLUSTER0		BIT(16)

struct alpine_msix_data {
	spinlock_t	msi_map_lock;
	phys_addr_t	addr;
	u32		spi_first;	/* The SGI number that MSIs start */
	u32		num_spis;	/* The number of SGIs for MSIs */
	unsigned long	*msi_map;
};

static int alpine_msix_allocate_sgi(struct alpine_msix_data *priv, int num_req)
{
	int first;

	guard(spinlock)(&priv->msi_map_lock);
	first = bitmap_find_next_zero_area(priv->msi_map, priv->num_spis, 0, num_req, 0);
	if (first >= priv->num_spis)
		return -ENOSPC;

	bitmap_set(priv->msi_map, first, num_req);
	return priv->spi_first + first;
}

static void alpine_msix_free_sgi(struct alpine_msix_data *priv, unsigned int sgi, int num_req)
{
	int first = sgi - priv->spi_first;

	guard(spinlock)(&priv->msi_map_lock);
	bitmap_clear(priv->msi_map, first, num_req);
}

static void alpine_msix_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
	struct alpine_msix_data *priv = irq_data_get_irq_chip_data(data);
	phys_addr_t msg_addr = priv->addr;

	msg_addr |= (data->hwirq << 3);
	msg->address_hi = upper_32_bits(msg_addr);
	msg->address_lo = lower_32_bits(msg_addr);
	msg->data = 0;
}

static struct irq_chip middle_irq_chip = {
	.name			= "alpine_msix_middle",
	.irq_mask		= irq_chip_mask_parent,
	.irq_unmask		= irq_chip_unmask_parent,
	.irq_eoi		= irq_chip_eoi_parent,
	.irq_set_affinity	= irq_chip_set_affinity_parent,
	.irq_compose_msi_msg	= alpine_msix_compose_msi_msg,
};

static int alpine_msix_gic_domain_alloc(struct irq_domain *domain, unsigned int virq, int sgi)
{
	struct irq_fwspec fwspec;
	struct irq_data *d;
	int ret;

	if (!is_of_node(domain->parent->fwnode))
		return -EINVAL;

	fwspec.fwnode = domain->parent->fwnode;
	fwspec.param_count = 3;
	fwspec.param[0] = 0;
	fwspec.param[1] = sgi;
	fwspec.param[2] = IRQ_TYPE_EDGE_RISING;

	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
	if (ret)
		return ret;

	d = irq_domain_get_irq_data(domain->parent, virq);
	d->chip->irq_set_type(d, IRQ_TYPE_EDGE_RISING);
	return 0;
}

static int alpine_msix_middle_domain_alloc(struct irq_domain *domain, unsigned int virq,
					   unsigned int nr_irqs, void *args)
{
	struct alpine_msix_data *priv = domain->host_data;
	int sgi, err, i;

	sgi = alpine_msix_allocate_sgi(priv, nr_irqs);
	if (sgi < 0)
		return sgi;

	for (i = 0; i < nr_irqs; i++) {
		err = alpine_msix_gic_domain_alloc(domain, virq + i, sgi + i);
		if (err)
			goto err_sgi;

		irq_domain_set_hwirq_and_chip(domain, virq + i, sgi + i,
					      &middle_irq_chip, priv);
	}
	return 0;

err_sgi:
	irq_domain_free_irqs_parent(domain, virq, i);
	alpine_msix_free_sgi(priv, sgi, nr_irqs);
	return err;
}

static void alpine_msix_middle_domain_free(struct irq_domain *domain, unsigned int virq,
					   unsigned int nr_irqs)
{
	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
	struct alpine_msix_data *priv = irq_data_get_irq_chip_data(d);

	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
	alpine_msix_free_sgi(priv, d->hwirq, nr_irqs);
}

static const struct irq_domain_ops alpine_msix_middle_domain_ops = {
	.select	= msi_lib_irq_domain_select,
	.alloc	= alpine_msix_middle_domain_alloc,
	.free	= alpine_msix_middle_domain_free,
};

#define ALPINE_MSI_FLAGS_REQUIRED  (MSI_FLAG_USE_DEF_DOM_OPS |		\
				    MSI_FLAG_USE_DEF_CHIP_OPS |		\
				    MSI_FLAG_PCI_MSI_MASK_PARENT)

#define ALPINE_MSI_FLAGS_SUPPORTED (MSI_GENERIC_FLAGS_MASK |		\
				    MSI_FLAG_PCI_MSIX)

static struct msi_parent_ops alpine_msi_parent_ops = {
	.supported_flags	= ALPINE_MSI_FLAGS_SUPPORTED,
	.required_flags		= ALPINE_MSI_FLAGS_REQUIRED,
	.chip_flags		= MSI_CHIP_FLAG_SET_EOI,
	.bus_select_token	= DOMAIN_BUS_NEXUS,
	.bus_select_mask	= MATCH_PCI_MSI,
	.prefix			= "ALPINE-",
	.init_dev_msi_info	= msi_lib_init_dev_msi_info,
};

static int alpine_msix_init_domains(struct alpine_msix_data *priv, struct device_node *node)
{
	struct irq_domain_info info = {
		.fwnode		= of_fwnode_handle(node),
		.ops		= &alpine_msix_middle_domain_ops,
		.host_data	= priv,
	};
	struct device_node *gic_node;

	gic_node = of_irq_find_parent(node);
	if (!gic_node) {
		pr_err("Failed to find the GIC node\n");
		return -ENODEV;
	}

	info.parent = irq_find_host(gic_node);
	of_node_put(gic_node);
	if (!info.parent) {
		pr_err("Failed to find the GIC domain\n");
		return -ENXIO;
	}

	if (!msi_create_parent_irq_domain(&info, &alpine_msi_parent_ops)) {
		pr_err("Failed to create MSI domain\n");
		return -ENOMEM;
	}
	return 0;
}

static int alpine_msix_init(struct device_node *node, struct device_node *parent)
{
	struct alpine_msix_data *priv __free(kfree) = kzalloc_obj(*priv);
	struct resource res;
	int ret;

	if (!priv)
		return -ENOMEM;

	spin_lock_init(&priv->msi_map_lock);

	ret = of_address_to_resource(node, 0, &res);
	if (ret) {
		pr_err("Failed to allocate resource\n");
		return ret;
	}

	/*
	 * The 20 least significant bits of addr provide direct information
	 * regarding the interrupt destination.
	 *
	 * To select the primary GIC as the target GIC, bits [18:17] must be set
	 * to 0x0. In this case, bit 16 (SPI_TARGET_CLUSTER0) must be set.
	 */
	priv->addr = res.start & GENMASK_ULL(63,20);
	priv->addr |= ALPINE_MSIX_SPI_TARGET_CLUSTER0;

	if (of_property_read_u32(node, "al,msi-base-spi", &priv->spi_first)) {
		pr_err("Unable to parse MSI base\n");
		return -EINVAL;
	}

	if (of_property_read_u32(node, "al,msi-num-spis", &priv->num_spis)) {
		pr_err("Unable to parse MSI numbers\n");
		return -EINVAL;
	}

	unsigned long *msi_map __free(kfree) = bitmap_zalloc(priv->num_spis, GFP_KERNEL);

	if (!msi_map)
		return -ENOMEM;
	priv->msi_map = msi_map;

	pr_debug("Registering %d msixs, starting at %d\n", priv->num_spis, priv->spi_first);

	ret = alpine_msix_init_domains(priv, node);
	if (ret)
		return ret;

	retain_and_null_ptr(priv);
	retain_and_null_ptr(msi_map);
	return 0;
}
IRQCHIP_DECLARE(alpine_msix, "al,alpine-msix", alpine_msix_init);