[PATCH 4/9] dma-buf: heaps: Add debugfs support

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

Add a callback to struct dma_heap_ops that heap providers can implement
to show information about the state of the heap in debugfs. A top-level
directory named "dma_heap" is created in debugfs and individual files
will be named after the heaps.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/dma-buf/dma-heap.c | 56 ++++++++++++++++++++++++++++++++++++++
 include/linux/dma-heap.h   |  2 ++
 2 files changed, 58 insertions(+)

diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
index cdddf0e24dce..f062f88365a5 100644
--- a/drivers/dma-buf/dma-heap.c
+++ b/drivers/dma-buf/dma-heap.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/cdev.h>
+#include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/dma-buf.h>
 #include <linux/dma-heap.h>
@@ -217,6 +218,46 @@ const char *dma_heap_get_name(struct dma_heap *heap)
 }
 EXPORT_SYMBOL(dma_heap_get_name);
 
+#ifdef CONFIG_DEBUG_FS
+static int dma_heap_debug_show(struct seq_file *s, void *unused)
+{
+	struct dma_heap *heap = s->private;
+	int err = 0;
+
+	if (heap->ops && heap->ops->show)
+		err = heap->ops->show(s, heap);
+
+	return err;
+}
+DEFINE_SHOW_ATTRIBUTE(dma_heap_debug);
+
+static struct dentry *dma_heap_debugfs_dir;
+
+static void dma_heap_init_debugfs(void)
+{
+	struct dentry *dir;
+
+	dir = debugfs_create_dir("dma_heap", NULL);
+	if (IS_ERR(dir))
+		return;
+
+	dma_heap_debugfs_dir = dir;
+}
+
+static void dma_heap_exit_debugfs(void)
+{
+	debugfs_remove_recursive(dma_heap_debugfs_dir);
+}
+#else
+static void dma_heap_init_debugfs(void)
+{
+}
+
+static void dma_heap_exit_debugfs(void)
+{
+}
+#endif
+
 /**
  * dma_heap_add - adds a heap to dmabuf heaps
  * @exp_info: information needed to register this heap
@@ -291,6 +332,13 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
 
 	/* Add heap to the list */
 	list_add(&heap->list, &heap_list);
+
+#ifdef CONFIG_DEBUG_FS
+	if (heap->ops && heap->ops->show)
+		debugfs_create_file(heap->name, 0444, dma_heap_debugfs_dir,
+				    heap, &dma_heap_debug_fops);
+#endif
+
 	mutex_unlock(&heap_list_lock);
 
 	return heap;
@@ -327,6 +375,14 @@ static int dma_heap_init(void)
 	}
 	dma_heap_class->devnode = dma_heap_devnode;
 
+	dma_heap_init_debugfs();
+
 	return 0;
 }
 subsys_initcall(dma_heap_init);
+
+static void __exit dma_heap_exit(void)
+{
+	dma_heap_exit_debugfs();
+}
+__exitcall(dma_heap_exit);
diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h
index 27d15f60950a..065f537177af 100644
--- a/include/linux/dma-heap.h
+++ b/include/linux/dma-heap.h
@@ -12,6 +12,7 @@
 #include <linux/types.h>
 
 struct dma_heap;
+struct seq_file;
 
 /**
  * struct dma_heap_ops - ops to operate on a given heap
@@ -24,6 +25,7 @@ struct dma_heap_ops {
 				    unsigned long len,
 				    u32 fd_flags,
 				    u64 heap_flags);
+	int (*show)(struct seq_file *s, struct dma_heap *heap);
 };
 
 /**
-- 
2.50.0