dca: registering requesters in multiple dca domains

This patch enables DCA support on multiple-IOH/multiple-IIO architectures.
It modifies dca module by replacing single dca_providers list
with dca_domains list, each domain containing separate list of providers.
This approach lets dca driver manage multiple domains, i.e. sets of providers
and requesters mapped back to the same PCI root complex device.
The driver takes care to register each requester to a provider
from the same domain.

Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: Maciej Sosnowski <[e-mail]>

drivers/dca/dca-core.c

···
 #include <linux/device.h>
 #include <linux/dca.h>
 
-#define DCA_VERSION "1.8"
+#define DCA_VERSION "1.12.1"
 
 MODULE_VERSION(DCA_VERSION);
 MODULE_LICENSE("GPL");
···
 
 static DEFINE_SPINLOCK(dca_lock);
 
-static LIST_HEAD(dca_providers);
+static LIST_HEAD(dca_domains);
+
+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 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) {
+		domain = dca_allocate_domain(rc);
+		if (domain)
+			list_add(&domain->node, &dca_domains);
+	}
+
+	return domain;
+}
 
 static struct dca_provider *dca_find_provider_by_dev(struct device *dev)
 {
-	struct dca_provider *dca, *ret = NULL;
+	struct dca_provider *dca;
+	struct pci_bus *rc;
+	struct dca_domain *domain;
 
-	list_for_each_entry(dca, &dca_providers, node) {
-		if ((!dev) || (dca->ops->dev_managed(dca, dev))) {
-			ret = dca;
-			break;
-		}
+	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;
 	}
 
-	return ret;
+	list_for_each_entry(dca, &domain->dca_providers, node)
+		if ((!dev) || (dca->ops->dev_managed(dca, dev)))
+			return dca;
+
+	return NULL;
 }
 
 /**
···
 	struct dca_provider *dca;
 	int err, slot = -ENODEV;
 	unsigned long flags;
+	struct pci_bus *pci_rc;
+	struct dca_domain *domain;
 
 	if (!dev)
 		return -EFAULT;
···
 		return -EEXIST;
 	}
 
-	list_for_each_entry(dca, &dca_providers, node) {
+	pci_rc = dca_pci_rc_from_dev(dev);
+	domain = dca_find_domain(pci_rc);
+	if (!domain) {
+		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;
···
 {
 	int err;
 	unsigned long flags;
+	struct dca_domain *domain;
 
 	err = dca_sysfs_add_provider(dca, dev);
 	if (err)
 		return err;
 
 	spin_lock_irqsave(&dca_lock, flags);
-	list_add(&dca->node, &dca_providers);
+	domain = dca_get_domain(dev);
+	if (!domain) {
+		spin_unlock_irqrestore(&dca_lock, flags);
+		return -ENODEV;
+	}
+	list_add(&dca->node, &domain->dca_providers);
 	spin_unlock_irqrestore(&dca_lock, flags);
 
 	blocking_notifier_call_chain(&dca_provider_chain,
···
  * unregister_dca_provider - remove a dca provider
  * @dca - struct created by alloc_dca_provider()
  */
-void unregister_dca_provider(struct dca_provider *dca)
+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);
 
 	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);
+
 	spin_unlock_irqrestore(&dca_lock, flags);
 
 	dca_sysfs_remove_provider(dca);

drivers/dma/ioat/pci.c

···
 
 	dev_err(&pdev->dev, "Removing dma and dca services\n");
 	if (device->dca) {
-		unregister_dca_provider(device->dca);
+		unregister_dca_provider(device->dca, &pdev->dev);
 		free_dca_provider(device->dca);
 		device->dca = NULL;
 	}

include/linux/dca.h

···
  */
 #ifndef DCA_H
 #define DCA_H
+
+#include <linux/pci.h>
+
 /* DCA Provider API */
 
 /* DCA Notifier Interface */
···
 	int			 id;
 };
 
+struct dca_domain {
+	struct list_head	node;
+	struct list_head	dca_providers;
+	struct pci_bus		*pci_rc;
+};
+
 struct dca_ops {
 	int	(*add_requester)    (struct dca_provider *, struct device *);
 	int	(*remove_requester) (struct dca_provider *, struct device *);
···
 struct dca_provider *alloc_dca_provider(struct dca_ops *ops, int priv_size);
 void free_dca_provider(struct dca_provider *dca);
 int register_dca_provider(struct dca_provider *dca, struct device *dev);
-void unregister_dca_provider(struct dca_provider *dca);
+void unregister_dca_provider(struct dca_provider *dca, struct device *dev);
 
 static inline void *dca_priv(struct dca_provider *dca)
 {