// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright(c) 2007 - 2009 Intel Corporation. All rights reserved.
 */

/*
 * This driver supports an interface for DCA clients and providers to meet.
 */

#include <linux/kernel.h>
#include <linux/notifier.h>
#include <linux/device.h>
#include <linux/dca.h>
#include <linux/slab.h>
#include <linux/module.h>

#define DCA_VERSION "1.12.1"

MODULE_VERSION(DCA_VERSION);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Intel Corporation");

static DEFINE_RAW_SPINLOCK(dca_lock);

static LIST_HEAD(dca_domains);

static BLOCKING_NOTIFIER_HEAD(dca_provider_chain);

static int dca_providers_blocked;

static struct pci_bus *dca_pci_rc_from_dev(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct pci_bus *bus = pdev->bus;

        while (bus->parent)
                bus = bus->parent;

        return bus;
}

static struct dca_domain *dca_allocate_domain(struct pci_bus *rc)
{
        struct dca_domain *domain;

        domain = kzalloc(sizeof(*domain), GFP_NOWAIT);
        if (!domain)
                return NULL;

        INIT_LIST_HEAD(&domain->dca_providers);
        domain->pci_rc = rc;

        return domain;
}

static void dca_free_domain(struct dca_domain *domain)
{
        list_del(&domain->node);
        kfree(domain);
}

static int dca_provider_ioat_ver_3_0(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);

        return ((pdev->vendor == PCI_VENDOR_ID_INTEL) &&
                ((pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG0) ||
                (pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG1) ||
                (pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG2) ||
                (pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG3) ||
                (pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG4) ||
                (pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG5) ||
                (pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG6) ||
                (pdev->device == PCI_DEVICE_ID_INTEL_IOAT_TBG7)));
}

static void unregister_dca_providers(void)
{
        struct dca_provider *dca, *_dca;
        struct list_head unregistered_providers;
        struct dca_domain *domain;
        unsigned long flags;

        blocking_notifier_call_chain(&dca_provider_chain,
                                     DCA_PROVIDER_REMOVE, NULL);

        INIT_LIST_HEAD(&unregistered_providers);

        raw_spin_lock_irqsave(&dca_lock, flags);

        if (list_empty(&dca_domains)) {
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return;
        }

        /* at this point only one domain in the list is expected */
        domain = list_first_entry(&dca_domains, struct dca_domain, node);

        list_for_each_entry_safe(dca, _dca, &domain->dca_providers, node)
                list_move(&dca->node, &unregistered_providers);

        dca_free_domain(domain);

        raw_spin_unlock_irqrestore(&dca_lock, flags);

        list_for_each_entry_safe(dca, _dca, &unregistered_providers, node) {
                dca_sysfs_remove_provider(dca);
                list_del(&dca->node);
        }
}

static struct dca_domain *dca_find_domain(struct pci_bus *rc)
{
        struct dca_domain *domain;

        list_for_each_entry(domain, &dca_domains, node)
                if (domain->pci_rc == rc)
                        return domain;

        return NULL;
}

static struct dca_domain *dca_get_domain(struct device *dev)
{
        struct pci_bus *rc;
        struct dca_domain *domain;

        rc = dca_pci_rc_from_dev(dev);
        domain = dca_find_domain(rc);

        if (!domain) {
                if (dca_provider_ioat_ver_3_0(dev) && !list_empty(&dca_domains))
                        dca_providers_blocked = 1;
        }

        return domain;
}

static struct dca_provider *dca_find_provider_by_dev(struct device *dev)
{
        struct dca_provider *dca;
        struct pci_bus *rc;
        struct dca_domain *domain;

        if (dev) {
                rc = dca_pci_rc_from_dev(dev);
                domain = dca_find_domain(rc);
                if (!domain)
                        return NULL;
        } else {
                if (!list_empty(&dca_domains))
                        domain = list_first_entry(&dca_domains,
                                                  struct dca_domain,
                                                  node);
                else
                        return NULL;
        }

        list_for_each_entry(dca, &domain->dca_providers, node)
                if ((!dev) || (dca->ops->dev_managed(dca, dev)))
                        return dca;

        return NULL;
}

/**
 * dca_add_requester - add a dca client to the list
 * @dev - the device that wants dca service
 */
int dca_add_requester(struct device *dev)
{
        struct dca_provider *dca;
        int err, slot = -ENODEV;
        unsigned long flags;
        struct pci_bus *pci_rc;
        struct dca_domain *domain;

        if (!dev)
                return -EFAULT;

        raw_spin_lock_irqsave(&dca_lock, flags);

        /* check if the requester has not been added already */
        dca = dca_find_provider_by_dev(dev);
        if (dca) {
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return -EEXIST;
        }

        pci_rc = dca_pci_rc_from_dev(dev);
        domain = dca_find_domain(pci_rc);
        if (!domain) {
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return -ENODEV;
        }

        list_for_each_entry(dca, &domain->dca_providers, node) {
                slot = dca->ops->add_requester(dca, dev);
                if (slot >= 0)
                        break;
        }

        raw_spin_unlock_irqrestore(&dca_lock, flags);

        if (slot < 0)
                return slot;

        err = dca_sysfs_add_req(dca, dev, slot);
        if (err) {
                raw_spin_lock_irqsave(&dca_lock, flags);
                if (dca == dca_find_provider_by_dev(dev))
                        dca->ops->remove_requester(dca, dev);
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return err;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(dca_add_requester);

/**
 * dca_remove_requester - remove a dca client from the list
 * @dev - the device that wants dca service
 */
int dca_remove_requester(struct device *dev)
{
        struct dca_provider *dca;
        int slot;
        unsigned long flags;

        if (!dev)
                return -EFAULT;

        raw_spin_lock_irqsave(&dca_lock, flags);
        dca = dca_find_provider_by_dev(dev);
        if (!dca) {
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return -ENODEV;
        }
        slot = dca->ops->remove_requester(dca, dev);
        raw_spin_unlock_irqrestore(&dca_lock, flags);

        if (slot < 0)
                return slot;

        dca_sysfs_remove_req(dca, slot);

        return 0;
}
EXPORT_SYMBOL_GPL(dca_remove_requester);

/**
 * dca_common_get_tag - return the dca tag (serves both new and old api)
 * @dev - the device that wants dca service
 * @cpu - the cpuid as returned by get_cpu()
 */
static u8 dca_common_get_tag(struct device *dev, int cpu)
{
        struct dca_provider *dca;
        u8 tag;
        unsigned long flags;

        raw_spin_lock_irqsave(&dca_lock, flags);

        dca = dca_find_provider_by_dev(dev);
        if (!dca) {
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return -ENODEV;
        }
        tag = dca->ops->get_tag(dca, dev, cpu);

        raw_spin_unlock_irqrestore(&dca_lock, flags);
        return tag;
}

/**
 * dca3_get_tag - return the dca tag to the requester device
 *                for the given cpu (new api)
 * @dev - the device that wants dca service
 * @cpu - the cpuid as returned by get_cpu()
 */
u8 dca3_get_tag(struct device *dev, int cpu)
{
        if (!dev)
                return -EFAULT;

        return dca_common_get_tag(dev, cpu);
}
EXPORT_SYMBOL_GPL(dca3_get_tag);

/**
 * dca_get_tag - return the dca tag for the given cpu (old api)
 * @cpu - the cpuid as returned by get_cpu()
 */
u8 dca_get_tag(int cpu)
{
        struct device *dev = NULL;

        return dca_common_get_tag(dev, cpu);
}
EXPORT_SYMBOL_GPL(dca_get_tag);

/**
 * alloc_dca_provider - get data struct for describing a dca provider
 * @ops - pointer to struct of dca operation function pointers
 * @priv_size - size of extra mem to be added for provider's needs
 */
struct dca_provider *alloc_dca_provider(const struct dca_ops *ops,
                                        int priv_size)
{
        struct dca_provider *dca;
        int alloc_size;

        alloc_size = (sizeof(*dca) + priv_size);
        dca = kzalloc(alloc_size, GFP_KERNEL);
        if (!dca)
                return NULL;
        dca->ops = ops;

        return dca;
}
EXPORT_SYMBOL_GPL(alloc_dca_provider);

/**
 * free_dca_provider - release the dca provider data struct
 * @ops - pointer to struct of dca operation function pointers
 * @priv_size - size of extra mem to be added for provider's needs
 */
void free_dca_provider(struct dca_provider *dca)
{
        kfree(dca);
}
EXPORT_SYMBOL_GPL(free_dca_provider);

/**
 * register_dca_provider - register a dca provider
 * @dca - struct created by alloc_dca_provider()
 * @dev - device providing dca services
 */
int register_dca_provider(struct dca_provider *dca, struct device *dev)
{
        int err;
        unsigned long flags;
        struct dca_domain *domain, *newdomain = NULL;

        raw_spin_lock_irqsave(&dca_lock, flags);
        if (dca_providers_blocked) {
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return -ENODEV;
        }
        raw_spin_unlock_irqrestore(&dca_lock, flags);

        err = dca_sysfs_add_provider(dca, dev);
        if (err)
                return err;

        raw_spin_lock_irqsave(&dca_lock, flags);
        domain = dca_get_domain(dev);
        if (!domain) {
                struct pci_bus *rc;

                if (dca_providers_blocked) {
                        raw_spin_unlock_irqrestore(&dca_lock, flags);
                        dca_sysfs_remove_provider(dca);
                        unregister_dca_providers();
                        return -ENODEV;
                }

                raw_spin_unlock_irqrestore(&dca_lock, flags);
                rc = dca_pci_rc_from_dev(dev);
                newdomain = dca_allocate_domain(rc);
                if (!newdomain)
                        return -ENODEV;
                raw_spin_lock_irqsave(&dca_lock, flags);
                /* Recheck, we might have raced after dropping the lock */
                domain = dca_get_domain(dev);
                if (!domain) {
                        domain = newdomain;
                        newdomain = NULL;
                        list_add(&domain->node, &dca_domains);
                }
        }
        list_add(&dca->node, &domain->dca_providers);
        raw_spin_unlock_irqrestore(&dca_lock, flags);

        blocking_notifier_call_chain(&dca_provider_chain,
                                     DCA_PROVIDER_ADD, NULL);
        kfree(newdomain);
        return 0;
}
EXPORT_SYMBOL_GPL(register_dca_provider);

/**
 * unregister_dca_provider - remove a dca provider
 * @dca - struct created by alloc_dca_provider()
 */
void unregister_dca_provider(struct dca_provider *dca, struct device *dev)
{
        unsigned long flags;
        struct pci_bus *pci_rc;
        struct dca_domain *domain;

        blocking_notifier_call_chain(&dca_provider_chain,
                                     DCA_PROVIDER_REMOVE, NULL);

        raw_spin_lock_irqsave(&dca_lock, flags);

        if (list_empty(&dca_domains)) {
                raw_spin_unlock_irqrestore(&dca_lock, flags);
                return;
        }

        list_del(&dca->node);

        pci_rc = dca_pci_rc_from_dev(dev);
        domain = dca_find_domain(pci_rc);
        if (list_empty(&domain->dca_providers))
                dca_free_domain(domain);

        raw_spin_unlock_irqrestore(&dca_lock, flags);

        dca_sysfs_remove_provider(dca);
}
EXPORT_SYMBOL_GPL(unregister_dca_provider);

/**
 * dca_register_notify - register a client's notifier callback
 */
void dca_register_notify(struct notifier_block *nb)
{
        blocking_notifier_chain_register(&dca_provider_chain, nb);
}
EXPORT_SYMBOL_GPL(dca_register_notify);

/**
 * dca_unregister_notify - remove a client's notifier callback
 */
void dca_unregister_notify(struct notifier_block *nb)
{
        blocking_notifier_chain_unregister(&dca_provider_chain, nb);
}
EXPORT_SYMBOL_GPL(dca_unregister_notify);

static int __init dca_init(void)
{
        pr_info("dca service started, version %s\n", DCA_VERSION);
        return dca_sysfs_init();
}

static void __exit dca_exit(void)
{
        dca_sysfs_exit();
}

arch_initcall(dca_init);
module_exit(dca_exit);