backlight: led_bl: Remove redundant of_match_ptr()

The driver depends on CONFIG_OF, it is not necessary to use
of_match_ptr() here.

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20230818012308.2058373-1-ruanjinjie@huawei.com
Signed-off-by: Lee Jones <lee@kernel.org>

backlight: led_bl: Take led_access lock when required

The led_access lock must be held when calling led_sysfs_enable() and
led_sysfs_disable(). This fixes warnings such as this:

[ 2.432495] ------------[ cut here ]------------
[ 2.437316] WARNING: CPU: 0 PID: 22 at drivers/leds/led-core.c:349 led_sysfs_disable+0x54/0x58
[ 2.446105] Modules linked in:
[ 2.449218] CPU: 0 PID: 22 Comm: kworker/u2:1 Not tainted 6.3.8+ #1
[ 2.456268] Hardware name: Generic AM3517 (Flattened Device Tree)
[ 2.462402] Workqueue: events_unbound deferred_probe_work_func
[ 2.468353] unwind_backtrace from show_stack+0x10/0x14
[ 2.473632] show_stack from dump_stack_lvl+0x24/0x2c
[ 2.478759] dump_stack_lvl from __warn+0x9c/0xc4
[ 2.483551] __warn from warn_slowpath_fmt+0x64/0xc0
[ 2.488586] warn_slowpath_fmt from led_sysfs_disable+0x54/0x58
[ 2.494567] led_sysfs_disable from led_bl_probe+0x20c/0x3b0
[ 2.500305] led_bl_probe from platform_probe+0x5c/0xb8
[ 2.505615] platform_probe from really_probe+0xc8/0x2a0
[ 2.510986] really_probe from __driver_probe_device+0x88/0x19c
[ 2.516967] __driver_probe_device from driver_probe_device+0x30/0xcc
[ 2.523498] driver_probe_device from __device_attach_driver+0x94/0xc4
[ 2.530090] __device_attach_driver from bus_for_each_drv+0x80/0xcc
[ 2.536437] bus_for_each_drv from __device_attach+0xf8/0x19c
[ 2.542236] __device_attach from bus_probe_device+0x8c/0x90
[ 2.547973] bus_probe_device from deferred_probe_work_func+0x80/0xb0
[ 2.554504] deferred_probe_work_func from process_one_work+0x228/0x4c0
[ 2.561187] process_one_work from worker_thread+0x1fc/0x4d0
[ 2.566925] worker_thread from kthread+0xb4/0xd0
[ 2.571685] kthread from ret_from_fork+0x14/0x2c
[ 2.576446] Exception stack(0xd0079fb0 to 0xd0079ff8)
[ 2.581573] 9fa0: 00000000 00000000 00000000 00000000
[ 2.589813] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.598052] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 2.604888] ---[ end trace 0000000000000000 ]---

Signed-off-by: Mans Rullgard <mans@mansr.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20230619160249.10414-1-mans@mansr.com
Signed-off-by: Lee Jones <lee@kernel.org>

backlight: led_bl: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230308073945.2336302-7-u.kleine-koenig@pengutronix.de

backlight: Use backlight_get_brightness() throughout

Introduce the backlight_get_brightness() helper in all
video/backlight/* drivers. This simplifies the code and align the
implementation of the update_status() operation across the different
backlight drivers.

Some of the drivers gains a little extra functionality by the change
as they now respect the fb_blank() ioctl.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

backlight: add led-backlight driver

This patch adds a led-backlight driver (led_bl), which is similar to
pwm_bl except the driver uses a LED class driver to adjust the
brightness in the HW. Multiple LEDs can be used for a single backlight.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Tony Lindgren <tony@atomide.com>