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authorJosé Pekkarinen <jose.pekkarinen@nokia.com>2016-04-11 10:41:07 +0300
committerJosé Pekkarinen <jose.pekkarinen@nokia.com>2016-04-13 08:17:18 +0300
commite09b41010ba33a20a87472ee821fa407a5b8da36 (patch)
treed10dc367189862e7ca5c592f033dc3726e1df4e3 /kernel/Documentation/filesystems/debugfs.txt
parentf93b97fd65072de626c074dbe099a1fff05ce060 (diff)
These changes are the raw update to linux-4.4.6-rt14. Kernel sources
are taken from kernel.org, and rt patch from the rt wiki download page. During the rebasing, the following patch collided: Force tick interrupt and get rid of softirq magic(I70131fb85). Collisions have been removed because its logic was found on the source already. Change-Id: I7f57a4081d9deaa0d9ccfc41a6c8daccdee3b769 Signed-off-by: José Pekkarinen <jose.pekkarinen@nokia.com>
Diffstat (limited to 'kernel/Documentation/filesystems/debugfs.txt')
-rw-r--r--kernel/Documentation/filesystems/debugfs.txt42
1 files changed, 41 insertions, 1 deletions
diff --git a/kernel/Documentation/filesystems/debugfs.txt b/kernel/Documentation/filesystems/debugfs.txt
index 88ab81c79..4f45f7114 100644
--- a/kernel/Documentation/filesystems/debugfs.txt
+++ b/kernel/Documentation/filesystems/debugfs.txt
@@ -51,6 +51,17 @@ operations should be provided; others can be included as needed. Again,
the return value will be a dentry pointer to the created file, NULL for
error, or ERR_PTR(-ENODEV) if debugfs support is missing.
+Create a file with an initial size, the following function can be used
+instead:
+
+ struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ const struct file_operations *fops,
+ loff_t file_size);
+
+file_size is the initial file size. The other parameters are the same
+as the function debugfs_create_file.
+
In a number of cases, the creation of a set of file operations is not
actually necessary; the debugfs code provides a number of helper functions
for simple situations. Files containing a single integer value can be
@@ -94,12 +105,20 @@ a variable of type size_t.
Boolean values can be placed in debugfs with:
struct dentry *debugfs_create_bool(const char *name, umode_t mode,
- struct dentry *parent, u32 *value);
+ struct dentry *parent, bool *value);
A read on the resulting file will yield either Y (for non-zero values) or
N, followed by a newline. If written to, it will accept either upper- or
lower-case values, or 1 or 0. Any other input will be silently ignored.
+Also, atomic_t values can be placed in debugfs with:
+
+ struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
+ struct dentry *parent, atomic_t *value)
+
+A read of this file will get atomic_t values, and a write of this file
+will set atomic_t values.
+
Another option is exporting a block of arbitrary binary data, with
this structure and function:
@@ -147,6 +166,27 @@ The "base" argument may be 0, but you may want to build the reg32 array
using __stringify, and a number of register names (macros) are actually
byte offsets over a base for the register block.
+If you want to dump an u32 array in debugfs, you can create file with:
+
+ struct dentry *debugfs_create_u32_array(const char *name, umode_t mode,
+ struct dentry *parent,
+ u32 *array, u32 elements);
+
+The "array" argument provides data, and the "elements" argument is
+the number of elements in the array. Note: Once array is created its
+size can not be changed.
+
+There is a helper function to create device related seq_file:
+
+ struct dentry *debugfs_create_devm_seqfile(struct device *dev,
+ const char *name,
+ struct dentry *parent,
+ int (*read_fn)(struct seq_file *s,
+ void *data));
+
+The "dev" argument is the device related to this debugfs file, and
+the "read_fn" is a function pointer which to be called to print the
+seq_file content.
There are a couple of other directory-oriented helper functions: