1 files changed, 46 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0180102dace1..9b8b696d4f15 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1657,6 +1657,52 @@ static inline void simple_transaction_set(struct file *file, size_t n)
         ar->size = n;
 }
 
+/*
+ * simple attribute files
+ *
+ * These attributes behave similar to those in sysfs:
+ *
+ * Writing to an attribute immediately sets a value, an open file can be
+ * written to multiple times.
+ *
+ * Reading from an attribute creates a buffer from the value that might get
+ * read with multiple read calls. When the attribute has been read
+ * completely, no further read calls are possible until the file is opened
+ * again.
+ *
+ * All attributes contain a text representation of a numeric value
+ * that are accessed with the get() and set() functions.
+ */
+#define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)            \
+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 struct file_operations __fops = {                                \
+        .owner   = THIS_MODULE,                                         \
+        .open    = __fops ## _open,                                     \
+        .release = simple_attr_close,                                   \
+        .read    = simple_attr_read,                                    \
+        .write   = simple_attr_write,                                   \
+};
+
+static inline void __attribute__((format(printf, 1, 2)))
+__simple_attr_check_format(const char *fmt, ...)
+{
+        /* don't do anything, just let the compiler check the arguments; */
+}
+
+int simple_attr_open(struct inode *inode, struct file *file,
+                     u64 (*get)(void *), void (*set)(void *, u64),
+                     const char *fmt);
+int simple_attr_close(struct inode *inode, struct file *file);
+ssize_t simple_attr_read(struct file *file, char __user *buf,
+                         size_t len, loff_t *ppos);
+ssize_t simple_attr_write(struct file *file, const char __user *buf,
+                          size_t len, loff_t *ppos);
+
+
 #ifdef CONFIG_SECURITY
 static inline char *alloc_secdata(void)
 {