HID: hid-wiimote-debug.c: Drop error checking for debugfs_create_file

This patch removes the error checking for debugfs_create_file
in hid-wiimote-debug.c.c. This is because the debugfs_create_file()
does not return NULL but an ERR_PTR after an error.
The DebugFS kernel API is developed in a way that the
caller can safely ignore the errors that occur during
the creation of DebugFS nodes.The debugfs Api handles
it gracefully. The check is unnecessary.

Link to the comment above debugfs_create_file:
https://elixir.bootlin.com/linux/latest/source/fs/debugfs/inode.c#L451

Signed-off-by: Osama Muhammad <osmtendev@gmail.com>
Reviewed-by: David Rheinsberg <david@readahead.eu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

HID: wiimote: fix DRM debug-attr to correctly parse input

We need to correctly zero-terminate the input to parse it. Otherwise, we
always end up interpreting it as numbers.
Furthermore, we actually want hexadecimal numbers instead of decimal. As
it is a debugfs interface, we can change the API at any time.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

HID: wiimote: lock DRM mode during debugfs overwrite

If we write a DRM mode via debugfs, we shouldn't allow normal operations
to overwrite this DRM mode. This is important if we want to debug
3rd-party devices and we want to see what data is sent on each mode.

If we write NULL/0 as DRM, the lock is removed again so the best matching
DRM is chosen by wiimote core.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

HID: wiimote: fix ctx pointer in debugfs DRM-write

single_open() stores the seq_file pointer in file->private_data. It stores
our ctx pointer in seq_file->private.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

HID: wiimote: extend driver description

The hid-wiimote driver supports more than the Wii Remote. Nintendo
produced many devices based on the Wii Remote, which have extension
devices built-in. It is not clear to many users, that these devices have
anything in common with the Wii Remote, so fix the driver description.

This also updates the copyright information for the coming hotplugging
rework.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

HID: Fix uninitialized variable "size" in hid-wiimote-debug

This variable is initialized conditionally, based on whether a wiimote
call succeeds. However, the logic is not obvious to the compiler so it
throws a warning. Eliminate the warning by initializing "size" to 0.

The warning is:
files/drivers/hid/hid-wiimote-debug.c:69:18: warning: 'size' may be used
uninitialized in this function [-Wmaybe-uninitialized]

Signed-off-by: Simon Que <sque@chromium.org>
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

simple_open: automatically convert to simple_open()

Many users of debugfs copy the implementation of default_open() when
they want to support a custom read/write function op. This leads to a
proliferation of the default_open() implementation across the entire
tree.

Now that the common implementation has been consolidated into libfs we
can replace all the users of this function with simple_open().

This replacement was done with the following semantic patch:

<smpl>
@ open @
identifier open_f != simple_open;
identifier i, f;
@@
-int open_f(struct inode *i, struct file *f)
-{
(
-if (i->i_private)
-f->private_data = i->i_private;
|
-f->private_data = i->i_private;
)
-return 0;
-}

@ has_open depends on open @
identifier fops;
identifier open.open_f;
@@
struct file_operations fops = {
...
-.open = open_f,
+.open = simple_open,
...
};
</smpl>

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

HID: wiimote: Allow direct DRM debug access

Keep track of current drm and add new debugfs file which reads or writes the
current DRM.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

HID: wiimote: Allow direct eeprom access

The wiimote provides direct access to parts of its eeprom. This implements read
support for small chunks of the eeprom. This isn't very fast but prevents the
reader from blocking the wiimote stream for too long.

Write support is not yet supported as the wiimote breaks if we overwrite its
memory. Use hidraw to reverse-engineer the eeprom before implementing write
support here.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

HID: wiimote: Add debugfs support stubs

Add initializer and deinitializer for debugfs support. This will later allow raw
eeprom access and direct DRM modifications to debug wiimote behaviour and
further protocol reverse-engineerings.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>