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 <dan.j.williams@intel.com>
Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>

2 files changed, 110 insertions, 14 deletions

diff --git a/drivers/dca/dca-core.c b/drivers/dca/dca-core.c
index 25b743abfb59..7e318de0904b 100644
--- a/drivers/dca/dca-core.c
+++ b/drivers/dca/dca-core.c
@@ -28,7 +28,7 @@
 #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");
@@ -36,20 +36,92 @@ MODULE_AUTHOR("Intel Corporation");
 
 static DEFINE_SPINLOCK(dca_lock);
 
-static LIST_HEAD(dca_providers);
+static LIST_HEAD(dca_domains);
 
-static struct dca_provider *dca_find_provider_by_dev(struct device *dev)
+static struct pci_bus *dca_pci_rc_from_dev(struct device *dev)
 {
-	struct dca_provider *dca, *ret = NULL;
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pci_bus *bus = pdev->bus;
 
-	list_for_each_entry(dca, &dca_providers, node) {
-		if ((!dev) || (dca->ops->dev_managed(dca, dev))) {
-			ret = dca;
-			break;
-		}
+	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;
+	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;
 	}
 
-	return ret;
+	list_for_each_entry(dca, &domain->dca_providers, node)
+		if ((!dev) || (dca->ops->dev_managed(dca, dev)))
+			return dca;
+
+	return NULL;
 }
 
 /**
@@ -61,6 +133,8 @@ 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;
@@ -74,7 +148,14 @@ int dca_add_requester(struct device *dev)
 		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;
@@ -222,13 +303,19 @@ int register_dca_provider(struct dca_provider *dca, struct device *dev)
 {
 	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,
@@ -241,15 +328,24 @@ 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)
+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);
diff --git a/drivers/dma/ioat/pci.c b/drivers/dma/ioat/pci.c
index c788fa266470..d545fae30f37 100644
--- a/drivers/dma/ioat/pci.c
+++ b/drivers/dma/ioat/pci.c
@@ -175,7 +175,7 @@ static void __devexit ioat_remove(struct pci_dev *pdev)
 
 	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;
 	}