dca-core.c

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/*
 * Copyright(c) 2007 - 2009 Intel Corporation. All rights reserved.
 *
 * 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; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * The full GNU General Public License is included in this distribution in the
 * file called COPYING.
 */

/*
 * 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;
}

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);

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);

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;
}

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);

u8 dca_get_tag(int cpu)
{
    struct device *dev = NULL;

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

struct dca_provider *alloc_dca_provider(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);

void free_dca_provider(struct dca_provider *dca)
{
    kfree(dca);
}
EXPORT_SYMBOL_GPL(free_dca_provider);

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);

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);

    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);

void dca_register_notify(struct notifier_block *nb)
{
    blocking_notifier_chain_register(&dca_provider_chain, nb);
}
EXPORT_SYMBOL_GPL(dca_register_notify);

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);