Commit 98210b7f authored by Arend van Spriel's avatar Arend van Spriel Committed by Greg Kroah-Hartman
Browse files

debugfs: add helper function to create device related seq_file 



This patch adds a helper function that simplifies adding a
so-called single_open sequence file for device drivers. The
calling device driver needs to provide a read function and
a device pointer. The field struct seq_file::private will
reference the device pointer upon call to the read function
so the driver can obtain his data from it and do its task
of providing the file content using seq_printf() calls and
alike. Using this helper function also gets rid of the need
to specify file operations per debugfs file.

Signed-off-by: default avatarArend van Spriel <arend@broadcom.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6df43c9b

fs/debugfs/file.c

+54 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/io.h>

#include <linux/slab.h>

#include <linux/atomic.h>

#include <linux/device.h>



static ssize_t default_read_file(struct file *file, char __user *buf,

				 size_t count, loff_t *ppos)
@@ -761,3 +762,56 @@ struct dentry *debugfs_create_regset32(const char *name, umode_t mode, 
EXPORT_SYMBOL_GPL(debugfs_create_regset32);



#endif /* CONFIG_HAS_IOMEM */



struct debugfs_devm_entry {

	int (*read)(struct seq_file *seq, void *data);

	struct device *dev;

};



static int debugfs_devm_entry_open(struct inode *inode, struct file *f)

{

	struct debugfs_devm_entry *entry = inode->i_private;



	return single_open(f, entry->read, entry->dev);

}



static const struct file_operations debugfs_devm_entry_ops = {

	.owner = THIS_MODULE,

	.open = debugfs_devm_entry_open,

	.release = single_release,

	.read = seq_read,

	.llseek = seq_lseek

};



/**

 * debugfs_create_devm_seqfile - create a debugfs file that is bound to device.

 *

 * @dev: device related to this debugfs file.

 * @name: name of the debugfs file.

 * @parent: a pointer to the parent dentry for this file.  This should be a

 *	directory dentry if set.  If this parameter is %NULL, then the

 *	file will be created in the root of the debugfs filesystem.

 * @read_fn: function pointer called to print the seq_file content.

 */

struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,

					   struct dentry *parent,

					   int (*read_fn)(struct seq_file *s,

							  void *data))

{

	struct debugfs_devm_entry *entry;



	if (IS_ERR(parent))

		return ERR_PTR(-ENOENT);



	entry = devm_kzalloc(dev, sizeof(*entry), GFP_KERNEL);

	if (!entry)

		return ERR_PTR(-ENOMEM);



	entry->read = read_fn;

	entry->dev = dev;



	return debugfs_create_file(name, S_IRUGO, parent, entry,

				   &debugfs_devm_entry_ops);

}

EXPORT_SYMBOL_GPL(debugfs_create_devm_seqfile);

include/linux/debugfs.h

+15 −1
Original line number Diff line number Diff line
@@ -99,6 +99,11 @@ struct dentry *debugfs_create_u32_array(const char *name, umode_t mode, 
					struct dentry *parent,

					u32 *array, u32 elements);



struct dentry *debugfs_create_devm_seqfile(struct device *dev, const char *name,

					   struct dentry *parent,

					   int (*read_fn)(struct seq_file *s,

							  void *data));



bool debugfs_initialized(void);



#else
@@ -251,6 +256,15 @@ static inline struct dentry *debugfs_create_u32_array(const char *name, umode_t 
	return ERR_PTR(-ENODEV);

}



static inline struct dentry *debugfs_create_devm_seqfile(struct device *dev,

							 const char *name,

							 struct dentry *parent,

					   int (*read_fn)(struct seq_file *s,

							  void *data))

{

	return ERR_PTR(-ENODEV);

}



#endif



#endif

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