iommu/omap: introduce new API for runtime suspend/resume control

This patch adds the support for the OMAP IOMMUs to be suspended
during the auto suspend/resume of the OMAP remoteproc devices. The
remote processors are auto suspended after a certain time of idle
or inactivity period. This is done by introducing two new API,
omap_iommu_domain_deactivate() and omap_iommu_domain_activate()
to allow the client users/master devices of the IOMMU devices to
deactivate & activate the IOMMU devices from their runtime
suspend/resume operations. There is no API exposed by the IOMMU
layer at present, and so these new API are added directly in the
OMAP IOMMU driver to minimize framework changes.

The API simply decrements and increments the runtime usage count
of the IOMMU devices and let the context be saved/restored using
the existing runtime pm callbacks.
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/omap-iommu.c

@@ -938,6 +938,64 @@ static void omap_iommu_restore_tlb_entries(struct omap_iommu *obj)
 	iotlb_lock_set(obj, &l);
 }
 
+/**
+ * omap_iommu_domain_deactivate - deactivate attached iommu devices
+ * @domain: iommu domain attached to the target iommu device
+ *
+ * This API allows the client devices of IOMMU devices to suspend
+ * the IOMMUs they control at runtime, after they are idled and
+ * suspended all activity. System Suspend will leverage the PM
+ * driver late callbacks.
+ **/
+int omap_iommu_domain_deactivate(struct iommu_domain *domain)
+{
+	struct omap_iommu_domain *omap_domain = to_omap_domain(domain);
+	struct omap_iommu_device *iommu;
+	struct omap_iommu *oiommu;
+	int i;
+
+	if (!omap_domain->dev)
+		return 0;
+
+	iommu = omap_domain->iommus;
+	iommu += (omap_domain->num_iommus - 1);
+	for (i = 0; i < omap_domain->num_iommus; i++, iommu--) {
+		oiommu = iommu->iommu_dev;
+		pm_runtime_put_sync(oiommu->dev);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(omap_iommu_domain_deactivate);
+
+/**
+ * omap_iommu_domain_activate - activate attached iommu devices
+ * @domain: iommu domain attached to the target iommu device
+ *
+ * This API allows the client devices of IOMMU devices to resume the
+ * IOMMUs they control at runtime, before they can resume operations.
+ * System Resume will leverage the PM driver late callbacks.
+ **/
+int omap_iommu_domain_activate(struct iommu_domain *domain)
+{
+	struct omap_iommu_domain *omap_domain = to_omap_domain(domain);
+	struct omap_iommu_device *iommu;
+	struct omap_iommu *oiommu;
+	int i;
+
+	if (!omap_domain->dev)
+		return 0;
+
+	iommu = omap_domain->iommus;
+	for (i = 0; i < omap_domain->num_iommus; i++, iommu++) {
+		oiommu = iommu->iommu_dev;
+		pm_runtime_get_sync(oiommu->dev);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(omap_iommu_domain_activate);
+
 /**
  * omap_iommu_runtime_suspend - disable an iommu device
  * @dev:	iommu device

include/linux/omap-iommu.h

@@ -10,12 +10,20 @@
 #ifndef _OMAP_IOMMU_H_
 #define _OMAP_IOMMU_H_
 
+struct iommu_domain;
+
 #ifdef CONFIG_OMAP_IOMMU
 extern void omap_iommu_save_ctx(struct device *dev);
 extern void omap_iommu_restore_ctx(struct device *dev);
+
+int omap_iommu_domain_deactivate(struct iommu_domain *domain);
+int omap_iommu_domain_activate(struct iommu_domain *domain);
 #else
 static inline void omap_iommu_save_ctx(struct device *dev) {}
 static inline void omap_iommu_restore_ctx(struct device *dev) {}
+
+static inline int omap_iommu_domain_deactivate(struct iommu_domain *domain) {}
+static inline int omap_iommu_domain_activate(struct iommu_domain *domain) {}
 #endif
 
 #endif