/*
 * linux/kernel/irq/msi.c
 *
 * Copyright (C) 2014 Intel Corp.
 * Author: Jiang Liu <jiang.liu@linux.intel.com>
 *
 * This file is licensed under GPLv2.
 *
 * This file contains common code to support Message Signalled Interrupt for
 * PCI compatible and non PCI compatible devices.
 */
#include <linux/types.h>
#include <linux/device.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/msi.h>
#include <linux/slab.h>

#include "internals.h"

/**
 * alloc_msi_entry - Allocate an initialize msi_entry
 * @dev:        Pointer to the device for which this is allocated
 * @nvec:       The number of vectors used in this entry
 * @affinity:   Optional pointer to an affinity mask array size of @nvec
 *
 * If @affinity is not NULL then a an affinity array[@nvec] is allocated
 * and the affinity masks from @affinity are copied.
 */
struct msi_desc *
alloc_msi_entry(struct device *dev, int nvec, const struct cpumask *affinity)
{
        struct msi_desc *desc;

        desc = kzalloc(sizeof(*desc), GFP_KERNEL);
        if (!desc)
                return NULL;

        INIT_LIST_HEAD(&desc->list);
        desc->dev = dev;
        desc->nvec_used = nvec;
        if (affinity) {
                desc->affinity = kmemdup(affinity,
                        nvec * sizeof(*desc->affinity), GFP_KERNEL);
                if (!desc->affinity) {
                        kfree(desc);
                        return NULL;
                }
        }

        return desc;
}

void free_msi_entry(struct msi_desc *entry)
{
        kfree(entry->affinity);
        kfree(entry);
}

void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
        *msg = entry->msg;
}

void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
{
        struct msi_desc *entry = irq_get_msi_desc(irq);

        __get_cached_msi_msg(entry, msg);
}
EXPORT_SYMBOL_GPL(get_cached_msi_msg);

#ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
static inline void irq_chip_write_msi_msg(struct irq_data *data,
                                          struct msi_msg *msg)
{
        data->chip->irq_write_msi_msg(data, msg);
}

/**
 * msi_domain_set_affinity - Generic affinity setter function for MSI domains
 * @irq_data:   The irq data associated to the interrupt
 * @mask:       The affinity mask to set
 * @force:      Flag to enforce setting (disable online checks)
 *
 * Intended to be used by MSI interrupt controllers which are
 * implemented with hierarchical domains.
 */
int msi_domain_set_affinity(struct irq_data *irq_data,
                            const struct cpumask *mask, bool force)
{
        struct irq_data *parent = irq_data->parent_data;
        struct msi_msg msg;
        int ret;

        ret = parent->chip->irq_set_affinity(parent, mask, force);
        if (ret >= 0 && ret != IRQ_SET_MASK_OK_DONE) {
                BUG_ON(irq_chip_compose_msi_msg(irq_data, &msg));
                irq_chip_write_msi_msg(irq_data, &msg);
        }

        return ret;
}

static int msi_domain_activate(struct irq_domain *domain,
                               struct irq_data *irq_data, bool early)
{
        struct msi_msg msg;

        BUG_ON(irq_chip_compose_msi_msg(irq_data, &msg));
        irq_chip_write_msi_msg(irq_data, &msg);
        return 0;
}

static void msi_domain_deactivate(struct irq_domain *domain,
                                  struct irq_data *irq_data)
{
        struct msi_msg msg;

        memset(&msg, 0, sizeof(msg));
        irq_chip_write_msi_msg(irq_data, &msg);
}

static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
                            unsigned int nr_irqs, void *arg)
{
        struct msi_domain_info *info = domain->host_data;
        struct msi_domain_ops *ops = info->ops;
        irq_hw_number_t hwirq = ops->get_hwirq(info, arg);
        int i, ret;

        if (irq_find_mapping(domain, hwirq) > 0)
                return -EEXIST;

        if (domain->parent) {
                ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
                if (ret < 0)
                        return ret;
        }

        for (i = 0; i < nr_irqs; i++) {
                ret = ops->msi_init(domain, info, virq + i, hwirq + i, arg);
                if (ret < 0) {
                        if (ops->msi_free) {
                                for (i--; i > 0; i--)
                                        ops->msi_free(domain, info, virq + i);
                        }
                        irq_domain_free_irqs_top(domain, virq, nr_irqs);
                        return ret;
                }
        }

        return 0;
}

static void msi_domain_free(struct irq_domain *domain, unsigned int virq,
                            unsigned int nr_irqs)
{
        struct msi_domain_info *info = domain->host_data;
        int i;

        if (info->ops->msi_free) {
                for (i = 0; i < nr_irqs; i++)
                        info->ops->msi_free(domain, info, virq + i);
        }
        irq_domain_free_irqs_top(domain, virq, nr_irqs);
}

static const struct irq_domain_ops msi_domain_ops = {
        .alloc          = msi_domain_alloc,
        .free           = msi_domain_free,
        .activate       = msi_domain_activate,
        .deactivate     = msi_domain_deactivate,
};

#ifdef GENERIC_MSI_DOMAIN_OPS
static irq_hw_number_t msi_domain_ops_get_hwirq(struct msi_domain_info *info,
                                                msi_alloc_info_t *arg)
{
        return arg->hwirq;
}

static int msi_domain_ops_prepare(struct irq_domain *domain, struct device *dev,
                                  int nvec, msi_alloc_info_t *arg)
{
        memset(arg, 0, sizeof(*arg));
        return 0;
}

static void msi_domain_ops_set_desc(msi_alloc_info_t *arg,
                                    struct msi_desc *desc)
{
        arg->desc = desc;
}
#else
#define msi_domain_ops_get_hwirq        NULL
#define msi_domain_ops_prepare          NULL
#define msi_domain_ops_set_desc         NULL
#endif /* !GENERIC_MSI_DOMAIN_OPS */

static int msi_domain_ops_init(struct irq_domain *domain,
                               struct msi_domain_info *info,
                               unsigned int virq, irq_hw_number_t hwirq,
                               msi_alloc_info_t *arg)
{
        irq_domain_set_hwirq_and_chip(domain, virq, hwirq, info->chip,
                                      info->chip_data);
        if (info->handler && info->handler_name) {
                __irq_set_handler(virq, info->handler, 0, info->handler_name);
                if (info->handler_data)
                        irq_set_handler_data(virq, info->handler_data);
        }
        return 0;
}

static int msi_domain_ops_check(struct irq_domain *domain,
                                struct msi_domain_info *info,
                                struct device *dev)
{
        return 0;
}

static struct msi_domain_ops msi_domain_ops_default = {
        .get_hwirq      = msi_domain_ops_get_hwirq,
        .msi_init       = msi_domain_ops_init,
        .msi_check      = msi_domain_ops_check,
        .msi_prepare    = msi_domain_ops_prepare,
        .set_desc       = msi_domain_ops_set_desc,
};

static void msi_domain_update_dom_ops(struct msi_domain_info *info)
{
        struct msi_domain_ops *ops = info->ops;

        if (ops == NULL) {
                info->ops = &msi_domain_ops_default;
                return;
        }

        if (ops->get_hwirq == NULL)
                ops->get_hwirq = msi_domain_ops_default.get_hwirq;
        if (ops->msi_init == NULL)
                ops->msi_init = msi_domain_ops_default.msi_init;
        if (ops->msi_check == NULL)
                ops->msi_check = msi_domain_ops_default.msi_check;
        if (ops->msi_prepare == NULL)
                ops->msi_prepare = msi_domain_ops_default.msi_prepare;
        if (ops->set_desc == NULL)
                ops->set_desc = msi_domain_ops_default.set_desc;
}

static void msi_domain_update_chip_ops(struct msi_domain_info *info)
{
        struct irq_chip *chip = info->chip;

        BUG_ON(!chip || !chip->irq_mask || !chip->irq_unmask);
        if (!chip->irq_set_affinity)
                chip->irq_set_affinity = msi_domain_set_affinity;
}

/**
 * msi_create_irq_domain - Create a MSI interrupt domain
 * @fwnode:     Optional fwnode of the interrupt controller
 * @info:       MSI domain info
 * @parent:     Parent irq domain
 */
struct irq_domain *msi_create_irq_domain(struct fwnode_handle *fwnode,
                                         struct msi_domain_info *info,
                                         struct irq_domain *parent)
{
        struct irq_domain *domain;

        if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)
                msi_domain_update_dom_ops(info);
        if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
                msi_domain_update_chip_ops(info);

        domain = irq_domain_create_hierarchy(parent, IRQ_DOMAIN_FLAG_MSI, 0,
                                             fwnode, &msi_domain_ops, info);

        if (domain && !domain->name && info->chip)
                domain->name = info->chip->name;

        return domain;
}

int msi_domain_prepare_irqs(struct irq_domain *domain, struct device *dev,
                            int nvec, msi_alloc_info_t *arg)
{
        struct msi_domain_info *info = domain->host_data;
        struct msi_domain_ops *ops = info->ops;
        int ret;

        ret = ops->msi_check(domain, info, dev);
        if (ret == 0)
                ret = ops->msi_prepare(domain, dev, nvec, arg);

        return ret;
}

int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
                             int virq, int nvec, msi_alloc_info_t *arg)
{
        struct msi_domain_info *info = domain->host_data;
        struct msi_domain_ops *ops = info->ops;
        struct msi_desc *desc;
        int ret = 0;

        for_each_msi_entry(desc, dev) {
                /* Don't even try the multi-MSI brain damage. */
                if (WARN_ON(!desc->irq || desc->nvec_used != 1)) {
                        ret = -EINVAL;
                        break;
                }

                if (!(desc->irq >= virq && desc->irq < (virq + nvec)))
                        continue;

                ops->set_desc(arg, desc);
                /* Assumes the domain mutex is held! */
                ret = irq_domain_alloc_irqs_hierarchy(domain, desc->irq, 1,
                                                      arg);
                if (ret)
                        break;

                irq_set_msi_desc_off(desc->irq, 0, desc);
        }

        if (ret) {
                /* Mop up the damage */
                for_each_msi_entry(desc, dev) {
                        if (!(desc->irq >= virq && desc->irq < (virq + nvec)))
                                continue;

                        irq_domain_free_irqs_common(domain, desc->irq, 1);
                }
        }

        return ret;
}

/*
 * Carefully check whether the device can use reservation mode. If
 * reservation mode is enabled then the early activation will assign a
 * dummy vector to the device. If the PCI/MSI device does not support
 * masking of the entry then this can result in spurious interrupts when
 * the device driver is not absolutely careful. But even then a malfunction
 * of the hardware could result in a spurious interrupt on the dummy vector
 * and render the device unusable. If the entry can be masked then the core
 * logic will prevent the spurious interrupt and reservation mode can be
 * used. For now reservation mode is restricted to PCI/MSI.
 */
static bool msi_check_reservation_mode(struct irq_domain *domain,
                                       struct msi_domain_info *info,
                                       struct device *dev)
{
        struct msi_desc *desc;

        if (domain->bus_token != DOMAIN_BUS_PCI_MSI)
                return false;

        if (!(info->flags & MSI_FLAG_MUST_REACTIVATE))
                return false;

        if (IS_ENABLED(CONFIG_PCI_MSI) && pci_msi_ignore_mask)
                return false;

        /*
         * Checking the first MSI descriptor is sufficient. MSIX supports
         * masking and MSI does so when the maskbit is set.
         */
        desc = first_msi_entry(dev);
        return desc->msi_attrib.is_msix || desc->msi_attrib.maskbit;
}

/**
 * msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
 * @domain:     The domain to allocate from
 * @dev:        Pointer to device struct of the device for which the interrupts
 *              are allocated
 * @nvec:       The number of interrupts to allocate
 *
 * Returns 0 on success or an error code.
 */
int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
                          int nvec)
{
        struct msi_domain_info *info = domain->host_data;
        struct msi_domain_ops *ops = info->ops;
        struct irq_data *irq_data;
        struct msi_desc *desc;
        msi_alloc_info_t arg;
        int i, ret, virq;
        bool can_reserve;

        ret = msi_domain_prepare_irqs(domain, dev, nvec, &arg);
        if (ret)
                return ret;

        for_each_msi_entry(desc, dev) {
                ops->set_desc(&arg, desc);

                virq = __irq_domain_alloc_irqs(domain, -1, desc->nvec_used,
                                               dev_to_node(dev), &arg, false,
                                               desc->affinity);
                if (virq < 0) {
                        ret = -ENOSPC;
                        if (ops->handle_error)
                                ret = ops->handle_error(domain, desc, ret);
                        if (ops->msi_finish)
                                ops->msi_finish(&arg, ret);
                        return ret;
                }

                for (i = 0; i < desc->nvec_used; i++) {
                        irq_set_msi_desc_off(virq, i, desc);
                        irq_debugfs_copy_devname(virq + i, dev);
                }
        }

        if (ops->msi_finish)
                ops->msi_finish(&arg, 0);

        can_reserve = msi_check_reservation_mode(domain, info, dev);

        for_each_msi_entry(desc, dev) {
                virq = desc->irq;
                if (desc->nvec_used == 1)
                        dev_dbg(dev, "irq %d for MSI\n", virq);
                else
                        dev_dbg(dev, "irq [%d-%d] for MSI\n",
                                virq, virq + desc->nvec_used - 1);
                /*
                 * This flag is set by the PCI layer as we need to activate
                 * the MSI entries before the PCI layer enables MSI in the
                 * card. Otherwise the card latches a random msi message.
                 */
                if (!(info->flags & MSI_FLAG_ACTIVATE_EARLY))
                        continue;

                irq_data = irq_domain_get_irq_data(domain, desc->irq);
                if (!can_reserve)
                        irqd_clr_can_reserve(irq_data);
                ret = irq_domain_activate_irq(irq_data, can_reserve);
                if (ret)
                        goto cleanup;
        }

        /*
         * If these interrupts use reservation mode, clear the activated bit
         * so request_irq() will assign the final vector.
         */
        if (can_reserve) {
                for_each_msi_entry(desc, dev) {
                        irq_data = irq_domain_get_irq_data(domain, desc->irq);
                        irqd_clr_activated(irq_data);
                }
        }
        return 0;

cleanup:
        for_each_msi_entry(desc, dev) {
                struct irq_data *irqd;

                if (desc->irq == virq)
                        break;

                irqd = irq_domain_get_irq_data(domain, desc->irq);
                if (irqd_is_activated(irqd))
                        irq_domain_deactivate_irq(irqd);
        }
        msi_domain_free_irqs(domain, dev);
        return ret;
}

/**
 * msi_domain_free_irqs - Free interrupts from a MSI interrupt @domain associated tp @dev
 * @domain:     The domain to managing the interrupts
 * @dev:        Pointer to device struct of the device for which the interrupts
 *              are free
 */
void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
{
        struct msi_desc *desc;

        for_each_msi_entry(desc, dev) {
                /*
                 * We might have failed to allocate an MSI early
                 * enough that there is no IRQ associated to this
                 * entry. If that's the case, don't do anything.
                 */
                if (desc->irq) {
                        irq_domain_free_irqs(desc->irq, desc->nvec_used);
                        desc->irq = 0;
                }
        }
}

/**
 * msi_get_domain_info - Get the MSI interrupt domain info for @domain
 * @domain:     The interrupt domain to retrieve data from
 *
 * Returns the pointer to the msi_domain_info stored in
 * @domain->host_data.
 */
struct msi_domain_info *msi_get_domain_info(struct irq_domain *domain)
{
        return (struct msi_domain_info *)domain->host_data;
}

#endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */