1 files changed, 94 insertions, 0 deletions

diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index 26ec39ddf21f..ed758b74ddf0 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -75,6 +75,73 @@ struct dax_dev {
         struct resource res[0];
 };
 
+static ssize_t id_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct dax_region *dax_region;
+        ssize_t rc = -ENXIO;
+
+        device_lock(dev);
+        dax_region = dev_get_drvdata(dev);
+        if (dax_region)
+                rc = sprintf(buf, "%d\n", dax_region->id);
+        device_unlock(dev);
+
+        return rc;
+}
+static DEVICE_ATTR_RO(id);
+
+static ssize_t region_size_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct dax_region *dax_region;
+        ssize_t rc = -ENXIO;
+
+        device_lock(dev);
+        dax_region = dev_get_drvdata(dev);
+        if (dax_region)
+                rc = sprintf(buf, "%llu\n", (unsigned long long)
+                                resource_size(&dax_region->res));
+        device_unlock(dev);
+
+        return rc;
+}
+static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
+                region_size_show, NULL);
+
+static ssize_t align_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct dax_region *dax_region;
+        ssize_t rc = -ENXIO;
+
+        device_lock(dev);
+        dax_region = dev_get_drvdata(dev);
+        if (dax_region)
+                rc = sprintf(buf, "%u\n", dax_region->align);
+        device_unlock(dev);
+
+        return rc;
+}
+static DEVICE_ATTR_RO(align);
+
+static struct attribute *dax_region_attributes[] = {
+        &dev_attr_region_size.attr,
+        &dev_attr_align.attr,
+        &dev_attr_id.attr,
+        NULL,
+};
+
+static const struct attribute_group dax_region_attribute_group = {
+        .name = "dax_region",
+        .attrs = dax_region_attributes,
+};
+
+static const struct attribute_group *dax_region_attribute_groups[] = {
+        &dax_region_attribute_group,
+        NULL,
+};
+
 static struct inode *dax_alloc_inode(struct super_block *sb)
 {
         return kmem_cache_alloc(dax_cache, GFP_KERNEL);
@@ -200,12 +267,31 @@ void dax_region_put(struct dax_region *dax_region)
 }
 EXPORT_SYMBOL_GPL(dax_region_put);
 
+static void dax_region_unregister(void *region)
+{
+        struct dax_region *dax_region = region;
+
+        sysfs_remove_groups(&dax_region->dev->kobj,
+                        dax_region_attribute_groups);
+        dax_region_put(dax_region);
+}
+
 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
                 struct resource *res, unsigned int align, void *addr,
                 unsigned long pfn_flags)
 {
         struct dax_region *dax_region;
 
+        /*
+         * The DAX core assumes that it can store its private data in
+         * parent->driver_data. This WARN is a reminder / safeguard for
+         * developers of device-dax drivers.
+         */
+        if (dev_get_drvdata(parent)) {
+                dev_WARN(parent, "dax core failed to setup private data\n");
+                return NULL;
+        }
+
         if (!IS_ALIGNED(res->start, align)
                         || !IS_ALIGNED(resource_size(res), align))
                 return NULL;
@@ -214,6 +300,7 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
         if (!dax_region)
                 return NULL;
 
+        dev_set_drvdata(parent, dax_region);
         memcpy(&dax_region->res, res, sizeof(*res));
         dax_region->pfn_flags = pfn_flags;
         kref_init(&dax_region->kref);
@@ -222,7 +309,14 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
         dax_region->align = align;
         dax_region->dev = parent;
         dax_region->base = addr;
+        if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
+                kfree(dax_region);
+                return NULL;;
+        }
 
+        kref_get(&dax_region->kref);
+        if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
+                return NULL;
         return dax_region;
 }
 EXPORT_SYMBOL_GPL(alloc_dax_region);