include/linux/debugfs.h

// SPDX-License-Identifier: GPL-2.0
/*
 *  debugfs.h - a tiny little debug file system
 *
 *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
 *  Copyright (C) 2004 IBM Inc.
 *
 *  debugfs is for people to use instead of /proc or /sys.
 *  See Documentation/filesystems/ for more details.
 */

#ifndef _DEBUGFS_H_
#define _DEBUGFS_H_

#include <linux/fs.h>
#include <linux/seq_file.h>

#include <linux/types.h>
#include <linux/compiler.h>

struct device;
struct file_operations;

struct debugfs_blob_wrapper {
	void *data;
	unsigned long size;
};

struct debugfs_reg32 {
	char *name;
	unsigned long offset;
};

struct debugfs_regset32 {
	const struct debugfs_reg32 *regs;
	int nregs;
	void __iomem *base;
	struct device *dev;	/* Optional device for Runtime PM */
};

struct debugfs_u32_array {
	u32 *array;
	u32 n_elements;
};

extern struct dentry *arch_debugfs_dir;

#define DEFINE_DEBUGFS_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, __is_signed)	\
static int __fops ## _open(struct inode *inode, struct file *file)	\
{									\
	__simple_attr_check_format(__fmt, 0ull);			\
	return simple_attr_open(inode, file, __get, __set, __fmt);	\
}									\
static const struct file_operations __fops = {				\
	.owner	 = THIS_MODULE,						\
	.open	 = __fops ## _open,					\
	.release = simple_attr_release,					\
	.read	 = debugfs_attr_read,					\
	.write	 = (__is_signed) ? debugfs_attr_write_signed : debugfs_attr_write,	\
}

#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt)		\
	DEFINE_DEBUGFS_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, false)

#define DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(__fops, __get, __set, __fmt)	\
	DEFINE_DEBUGFS_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, true)

typedef struct vfsmount *(*debugfs_automount_t)(struct dentry *, void *);

struct debugfs_short_fops {
	ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
	ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
	loff_t (*llseek) (struct file *, loff_t, int);
};

#if defined(CONFIG_DEBUG_FS)

struct dentry *debugfs_lookup(const char *name, struct dentry *parent);

struct dentry *debugfs_create_file_full(const char *name, umode_t mode,
					struct dentry *parent, void *data,
					const void *aux,
					const struct file_operations *fops);
struct dentry *debugfs_create_file_short(const char *name, umode_t mode,
					 struct dentry *parent, void *data,
					 const void *aux,
					 const struct debugfs_short_fops *fops);

/**
 * debugfs_create_file - create a file in the debugfs filesystem
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have.
 * @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.
 * @data: a pointer to something that the caller will want to get to later
 *        on.  The inode.i_private pointer will point to this value on
 *        the open() call.
 * @fops: a pointer to a struct file_operations or struct debugfs_short_fops that
 *        should be used for this file.
 *
 * This is the basic "create a file" function for debugfs.  It allows for a
 * wide range of flexibility in creating a file, or a directory (if you want
 * to create a directory, the debugfs_create_dir() function is
 * recommended to be used instead.)
 *
 * This function will return a pointer to a dentry if it succeeds.  This
 * pointer must be passed to the debugfs_remove() function when the file is
 * to be removed (no automatic cleanup happens if your module is unloaded,
 * you are responsible here.)  If an error occurs, ERR_PTR(-ERROR) will be
 * returned.
 *
 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 * returned.
 *
 * If fops points to a struct debugfs_short_fops, then simple_open() will be
 * used for the open, and only read/write/llseek are supported and are proxied,
 * so no module reference or release are needed.
 *
 * NOTE: it's expected that most callers should _ignore_ the errors returned
 * by this function. Other debugfs functions handle the fact that the "dentry"
 * passed to them could be an error and they don't crash in that case.
 * Drivers should generally work fine even if debugfs fails to init anyway.
 */
#define debugfs_create_file(name, mode, parent, data, fops)			\
	_Generic(fops,								\
		 const struct file_operations *: debugfs_create_file_full,	\
		 const struct debugfs_short_fops *: debugfs_create_file_short,	\
		 struct file_operations *: debugfs_create_file_full,		\
		 struct debugfs_short_fops *: debugfs_create_file_short)	\
		(name, mode, parent, data, NULL, fops)

#define debugfs_create_file_aux(name, mode, parent, data, aux, fops)		\
	_Generic(fops,								\
		 const struct file_operations *: debugfs_create_file_full,	\
		 const struct debugfs_short_fops *: debugfs_create_file_short,	\
		 struct file_operations *: debugfs_create_file_full,		\
		 struct debugfs_short_fops *: debugfs_create_file_short)	\
		(name, mode, parent, data, aux, fops)

struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
				   struct dentry *parent, void *data,
				   const struct file_operations *fops);

void debugfs_create_file_size(const char *name, umode_t mode,
			      struct dentry *parent, void *data,
			      const struct file_operations *fops,
			      loff_t file_size);

struct dentry *debugfs_create_dir(const char *name, struct dentry *parent);

struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
				      const char *dest);

struct dentry *debugfs_create_automount(const char *name,
					struct dentry *parent,
					debugfs_automount_t f,
					void *data);

void debugfs_remove(struct dentry *dentry);
#define debugfs_remove_recursive debugfs_remove

void debugfs_lookup_and_remove(const char *name, struct dentry *parent);

const struct file_operations *debugfs_real_fops(const struct file *filp);
const void *debugfs_get_aux(const struct file *file);

int debugfs_file_get(struct dentry *dentry);
void debugfs_file_put(struct dentry *dentry);

ssize_t debugfs_attr_read(struct file *file, char __user *buf,
			size_t len, loff_t *ppos);
ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
			size_t len, loff_t *ppos);
ssize_t debugfs_attr_write_signed(struct file *file, const char __user *buf,
			size_t len, loff_t *ppos);

int debugfs_change_name(struct dentry *dentry, const char *fmt, ...) __printf(2, 3);

void debugfs_create_u8(const char *name, umode_t mode, struct dentry *parent,
		       u8 *value);
void debugfs_create_u16(const char *name, umode_t mode, struct dentry *parent,
			u16 *value);
void debugfs_create_u32(const char *name, umode_t mode, struct dentry *parent,
			u32 *value);
void debugfs_create_u64(const char *name, umode_t mode, struct dentry *parent,
			u64 *value);
void debugfs_create_ulong(const char *name, umode_t mode, struct dentry *parent,
			  unsigned long *value);
void debugfs_create_x8(const char *name, umode_t mode, struct dentry *parent,
		       u8 *value);
void debugfs_create_x16(const char *name, umode_t mode, struct dentry *parent,
			u16 *value);
void debugfs_create_x32(const char *name, umode_t mode, struct dentry *parent,
			u32 *value);
void debugfs_create_x64(const char *name, umode_t mode, struct dentry *parent,
			u64 *value);
void debugfs_create_size_t(const char *name, umode_t mode,
			   struct dentry *parent, size_t *value);
void debugfs_create_atomic_t(const char *name, umode_t mode,
			     struct dentry *parent, atomic_t *value);
void debugfs_create_bool(const char *name, umode_t mode, struct dentry *parent,
			 bool *value);
void debugfs_create_str(const char *name, umode_t mode,
			struct dentry *parent, char **value);

struct dentry *debugfs_create_blob(const char *name, umode_t mode,
				  struct dentry *parent,
				  struct debugfs_blob_wrapper *blob);

void debugfs_create_regset32(const char *name, umode_t mode,
			     struct dentry *parent,
			     struct debugfs_regset32 *regset);

void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
			  int nregs, void __iomem *base, char *prefix);

void debugfs_create_u32_array(const char *name, umode_t mode,
			      struct dentry *parent,
			      struct debugfs_u32_array *array);

void 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);

ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf,
			       size_t count, loff_t *ppos);

ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf,
				size_t count, loff_t *ppos);

ssize_t debugfs_read_file_str(struct file *file, char __user *user_buf,
			      size_t count, loff_t *ppos);

/**
 * struct debugfs_cancellation - cancellation data
 * @list: internal, for keeping track
 * @cancel: callback to call
 * @cancel_data: extra data for the callback to call
 */
struct debugfs_cancellation {
	struct list_head list;
	void (*cancel)(struct dentry *, void *);
	void *cancel_data;
};

void __acquires(cancellation)
debugfs_enter_cancellation(struct file *file,
			   struct debugfs_cancellation *cancellation);
void __releases(cancellation)
debugfs_leave_cancellation(struct file *file,
			   struct debugfs_cancellation *cancellation);

#else

#include <linux/err.h>

/*
 * We do not return NULL from these functions if CONFIG_DEBUG_FS is not enabled
 * so users have a chance to detect if there was a real error or not.  We don't
 * want to duplicate the design decision mistakes of procfs and devfs again.
 */

static inline struct dentry *debugfs_lookup(const char *name,
					    struct dentry *parent)
{
	return ERR_PTR(-ENODEV);
}

static inline struct dentry *debugfs_create_file_aux(const char *name,
					umode_t mode, struct dentry *parent,
					void *data, void *aux,
					const void *fops)
{
	return ERR_PTR(-ENODEV);
}

static inline struct dentry *debugfs_create_file(const char *name, umode_t mode,
					struct dentry *parent, void *data,
					const void *fops)
{
	return ERR_PTR(-ENODEV);
}

static inline struct dentry *debugfs_create_file_unsafe(const char *name,
					umode_t mode, struct dentry *parent,
					void *data,
					const struct file_operations *fops)
{
	return ERR_PTR(-ENODEV);
}

static inline void debugfs_create_file_size(const char *name, umode_t mode,
					    struct dentry *parent, void *data,
					    const struct file_operations *fops,
					    loff_t file_size)
{ }

static inline struct dentry *debugfs_create_dir(const char *name,
						struct dentry *parent)
{
	return ERR_PTR(-ENODEV);
}

static inline struct dentry *debugfs_create_symlink(const char *name,
						    struct dentry *parent,
						    const char *dest)
{
	return ERR_PTR(-ENODEV);
}

static inline struct dentry *debugfs_create_automount(const char *name,
					struct dentry *parent,
					debugfs_automount_t f,
					void *data)
{
	return ERR_PTR(-ENODEV);
}

static inline void debugfs_remove(struct dentry *dentry)
{ }

static inline void debugfs_remove_recursive(struct dentry *dentry)
{ }

static inline void debugfs_lookup_and_remove(const char *name,
					     struct dentry *parent)
{ }

const struct file_operations *debugfs_real_fops(const struct file *filp);
void *debugfs_get_aux(const struct file *file);

static inline int debugfs_file_get(struct dentry *dentry)
{
	return 0;
}

static inline void debugfs_file_put(struct dentry *dentry)
{ }

static inline ssize_t debugfs_attr_read(struct file *file, char __user *buf,
					size_t len, loff_t *ppos)
{
	return -ENODEV;
}

static inline ssize_t debugfs_attr_write(struct file *file,
					const char __user *buf,
					size_t len, loff_t *ppos)
{
	return -ENODEV;
}

static inline ssize_t debugfs_attr_write_signed(struct file *file,
					const char __user *buf,
					size_t len, loff_t *ppos)
{
	return -ENODEV;
}

static inline int __printf(2, 3) debugfs_change_name(struct dentry *dentry,
					const char *fmt, ...)
{
	return -ENODEV;
}

static inline void debugfs_create_u8(const char *name, umode_t mode,
				     struct dentry *parent, u8 *value) { }

static inline void debugfs_create_u16(const char *name, umode_t mode,
				      struct dentry *parent, u16 *value) { }

static inline void debugfs_create_u32(const char *name, umode_t mode,
				      struct dentry *parent, u32 *value) { }

static inline void debugfs_create_u64(const char *name, umode_t mode,
				      struct dentry *parent, u64 *value) { }

static inline void debugfs_create_ulong(const char *name, umode_t mode,
					struct dentry *parent,
					unsigned long *value) { }

static inline void debugfs_create_x8(const char *name, umode_t mode,
				     struct dentry *parent, u8 *value) { }

static inline void debugfs_create_x16(const char *name, umode_t mode,
				      struct dentry *parent, u16 *value) { }

static inline void debugfs_create_x32(const char *name, umode_t mode,
				      struct dentry *parent, u32 *value) { }

static inline void debugfs_create_x64(const char *name, umode_t mode,
				      struct dentry *parent, u64 *value) { }

static inline void debugfs_create_size_t(const char *name, umode_t mode,
					 struct dentry *parent, size_t *value)
{ }

static inline void debugfs_create_atomic_t(const char *name, umode_t mode,
					   struct dentry *parent,
					   atomic_t *value)
{ }

static inline void debugfs_create_bool(const char *name, umode_t mode,
				       struct dentry *parent, bool *value) { }

static inline void debugfs_create_str(const char *name, umode_t mode,
				      struct dentry *parent,
				      char **value)
{ }

static inline struct dentry *debugfs_create_blob(const char *name, umode_t mode,
				  struct dentry *parent,
				  struct debugfs_blob_wrapper *blob)
{
	return ERR_PTR(-ENODEV);
}

static inline void debugfs_create_regset32(const char *name, umode_t mode,
					   struct dentry *parent,
					   struct debugfs_regset32 *regset)
{
}

static inline void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
			 int nregs, void __iomem *base, char *prefix)
{
}

static inline bool debugfs_initialized(void)
{
	return false;
}

static inline void debugfs_create_u32_array(const char *name, umode_t mode,
					    struct dentry *parent,
					    struct debugfs_u32_array *array)
{
}

static inline void debugfs_create_devm_seqfile(struct device *dev,
					       const char *name,
					       struct dentry *parent,
					       int (*read_fn)(struct seq_file *s,
							      void *data))
{
}

static inline ssize_t debugfs_read_file_bool(struct file *file,
					     char __user *user_buf,
					     size_t count, loff_t *ppos)
{
	return -ENODEV;
}

static inline ssize_t debugfs_write_file_bool(struct file *file,
					      const char __user *user_buf,
					      size_t count, loff_t *ppos)
{
	return -ENODEV;
}

static inline ssize_t debugfs_read_file_str(struct file *file,
					    char __user *user_buf,
					    size_t count, loff_t *ppos)
{
	return -ENODEV;
}

#endif

#define debugfs_create_file_aux_num(name, mode, parent, data, n, fops) \
	debugfs_create_file_aux(name, mode, parent, data, \
				(void *)(unsigned long)n, fops)
#define debugfs_get_aux_num(f) (unsigned long)debugfs_get_aux(f)

/**
 * debugfs_create_xul - create a debugfs file that is used to read and write an
 * unsigned long value, formatted in hexadecimal
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @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.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 */
static inline void debugfs_create_xul(const char *name, umode_t mode,
				      struct dentry *parent,
				      unsigned long *value)
{
	if (sizeof(*value) == sizeof(u32))
		debugfs_create_x32(name, mode, parent, (u32 *)value);
	else
		debugfs_create_x64(name, mode, parent, (u64 *)value);
}

#endif