staging: fieldbus: make fieldbus_class constant

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the fieldbus_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Link: https://lore.kernel.org/r/20240301-class_cleanup-staging-v1-1-34db2a5b0eb0@marliere.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fieldbus: Remove usage of the deprecated ida_simple_xx() API

ida_alloc() and ida_free() should be preferred to the deprecated
ida_simple_get() and ida_simple_remove().

Note that the upper limit of ida_simple_get() is exclusive, but the one of
ida_alloc_max() is inclusive. So a -1 has been added when needed.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/d305b97b1064ba7e026232fb8c2a0783ba1b1098.1705227001.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers: remove struct module * setting from struct class

There is no need to manually set the owner of a struct class, as the
registering function does it automatically, so remove all of the
explicit settings from various drivers that did so as it is unneeded.

This allows us to remove this pointer entirely from this structure going
forward.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230313181843.1207845-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fieldbus: use sysfs_emit() in show functions

The show() methods should only use sysfs_emit() when formatting values
to be returned to the user space.
Ref: Documentation/filesystems/sysfs.rst
Issue identified by coccicheck.

Signed-off-by: Deepak R Varma <drv@mailo.com>
Link: https://lore.kernel.org/r/Y2uEIzebbM/Fs5Jz@qemulion
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fieldbus: use kobj_to_dev() to get device

Use kobj_to_dev() instead of container_of()

Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20201117025933.668938-1-dingxiang@cmss.chinamobile.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fieldbus core: remove unused strings

Remove two unused static const strings - a leftover from
a previous stage. Interestingly, neither gcc nor sparse
warned about their presence.

Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Link: https://lore.kernel.org/r/20190918183552.28959-2-TheSven73@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: fieldbus: solve warning incorrect type dev_core.c

These changes solve a warning realated to an incorrect type inilizer in the function
fieldbus_poll.

Signed-off-by: Oscar Gomez Fuente <oscargomezf@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: add Fieldbus Device subsystem.

Fieldbus device (client) adapters allow data exchange with a PLC aka.
"Fieldbus Controller" over a fieldbus (Profinet, FLNet, etc.)

They are typically used when a Linux device wants to expose itself
as an actuator, motor, console light, switch, etc. over the fieldbus.

This framework is designed to provide a generic interface to Fieldbus
Devices from both the Linux Kernel and the userspace.

Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>