iommu: Add DOMAIN_ATTR_WINDOWS domain attribute

This attribute can be used to set and get the number of
subwindows on IOMMUs that are window-based.

Signed-off-by: Joerg Roedel <joro@8bytes.org>

2 files changed, 35 insertions, 3 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b3aced7356cc..b972d430d92b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -891,6 +891,7 @@ int iommu_domain_get_attr(struct iommu_domain *domain,
         struct iommu_domain_geometry *geometry;
         bool *paging;
         int ret = 0;
+        u32 *count;
 
         switch (attr) {
         case DOMAIN_ATTR_GEOMETRY:
@@ -902,6 +903,15 @@ int iommu_domain_get_attr(struct iommu_domain *domain,
                 paging  = data;
                 *paging = (domain->ops->pgsize_bitmap != 0UL);
                 break;
+        case DOMAIN_ATTR_WINDOWS:
+                count = data;
+
+                if (domain->ops->domain_get_windows != NULL)
+                        *count = domain->ops->domain_get_windows(domain);
+                else
+                        ret = -ENODEV;
+
+                break;
         default:
                 if (!domain->ops->domain_get_attr)
                         return -EINVAL;
@@ -916,9 +926,26 @@ EXPORT_SYMBOL_GPL(iommu_domain_get_attr);
 int iommu_domain_set_attr(struct iommu_domain *domain,
                           enum iommu_attr attr, void *data)
 {
-        if (!domain->ops->domain_set_attr)
-                return -EINVAL;
+        int ret = 0;
+        u32 *count;
+
+        switch (attr) {
+        case DOMAIN_ATTR_WINDOWS:
+                count = data;
+
+                if (domain->ops->domain_set_windows != NULL)
+                        ret = domain->ops->domain_set_windows(domain, *count);
+                else
+                        ret = -ENODEV;
 
-        return domain->ops->domain_set_attr(domain, attr, data);
+                break;
+        default:
+                if (domain->ops->domain_set_attr == NULL)
+                        return -EINVAL;
+
+                ret = domain->ops->domain_set_attr(domain, attr, data);
+        }
+
+        return ret;
 }
 EXPORT_SYMBOL_GPL(iommu_domain_set_attr);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5ea3d7250917..ba3b8a98a049 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -60,6 +60,7 @@ struct iommu_domain {
 enum iommu_attr {
         DOMAIN_ATTR_GEOMETRY,
         DOMAIN_ATTR_PAGING,
+        DOMAIN_ATTR_WINDOWS,
         DOMAIN_ATTR_MAX,
 };
 
@@ -106,6 +107,10 @@ struct iommu_ops {
         int (*domain_window_enable)(struct iommu_domain *domain, u32 wnd_nr,
                                     phys_addr_t paddr, u64 size);
         void (*domain_window_disable)(struct iommu_domain *domain, u32 wnd_nr);
+        /* Set the numer of window per domain */
+        int (*domain_set_windows)(struct iommu_domain *domain, u32 w_count);
+        /* Get the numer of window per domain */
+        u32 (*domain_get_windows)(struct iommu_domain *domain);
 
         unsigned long pgsize_bitmap;
 };