backlight: add led-backlight driver

Commit Message

Pavel Machek Feb. 19, 2020, 7:14 p.m. UTC

From: Tomi Valkeinen <[e-mail]>

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 <[e-mail]>
Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
Acked-by: Pavel Machek <[e-mail]>
Reviewed-by: Daniel Thompson <[e-mail]>
Acked-by: Lee Jones <[e-mail]>
Acked-by: Tony Lindgren <[e-mail]>
Tested-by: Tony Lindgren <[e-mail]>
Signed-off-by: Pavel Machek <[e-mail]>
---
 drivers/video/backlight/Kconfig  |   7 ++
 drivers/video/backlight/Makefile |   1 +
 drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 268 insertions(+)
 create mode 100644 drivers/video/backlight/led_bl.c

Hi!

Here's the version of the driver I have. AFAICT
default-brightness-level handling is ok, so does not need to be
changed.

Lee, it would be easiest for me if you could apply it to your tree and
push, but given enough time I can push it to Linus, too.

Thanks,
								Pavel

Comments

Tony Lindgren Feb. 19, 2020, 7:45 p.m. UTC | #1

* Pavel Machek <[e-mail]> [200219 19:15]:
> From: Tomi Valkeinen <[e-mail]>
> 
> 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 <[e-mail]>
> Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
> Acked-by: Pavel Machek <[e-mail]>
> Reviewed-by: Daniel Thompson <[e-mail]>
> Acked-by: Lee Jones <[e-mail]>
> Acked-by: Tony Lindgren <[e-mail]>
> Tested-by: Tony Lindgren <[e-mail]>
> Signed-off-by: Pavel Machek <[e-mail]>
> ---
>  drivers/video/backlight/Kconfig  |   7 ++
>  drivers/video/backlight/Makefile |   1 +
>  drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 268 insertions(+)
>  create mode 100644 drivers/video/backlight/led_bl.c
> 
> Hi!
> 
> Here's the version of the driver I have. AFAICT
> default-brightness-level handling is ok, so does not need to be
> changed.
> 
> Lee, it would be easiest for me if you could apply it to your tree and
> push, but given enough time I can push it to Linus, too.

Oh you're using quoted-printable for patches.. Got it applied now,
and it still works. Below is also the related dts change that
I tested with.

Feel free to pick the dts change too, naturally that should
not be applied before the driver.

If you guys instead want me to pick these both into my fixes
branch, just let me know and I'll do the explaining why these
are needed as fixes. Basically we no longer have a way to enable
the LCD backlight for droid4 manually starting with v5.6-rc1
unlike earlier.

Regards,

Tony

8< ------------------
From tony Mon Sep 17 00:00:00 2001
From: Tony Lindgren <[e-mail]>
Date: Wed, 19 Feb 2020 11:25:27 -0800
Subject: [PATCH] ARM: dts: droid4: Configure LED backlight for lm3532

With the LED backlight changes merged, we still need the dts configured
to have backlight working for droid4. Based on an earlier patch from
Pavel Machek <[e-mail]>, let's configure the backlight but update
the value range to be more usable.

We have a range of 256 register values split into 8 steps, so we can
generate the brightness levels backwards with:

$ for i in 0 1 2 3 4 5 6 7; do echo "255 - ${i} * (256 / 8)" | bc; done

To avoid more confusion why the LCD backlight is still not on, let's
also enable LED backlight as a loadable module for omap2plus_defconfig.

Cc: Merlijn Wajer <[e-mail]>
Cc: Pavel Machek <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>
---
 arch/arm/boot/dts/motorola-mapphone-common.dtsi | 13 +++++++++++--
 arch/arm/configs/omap2plus_defconfig            |  1 +
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/motorola-mapphone-common.dtsi b/arch/arm/boot/dts/motorola-mapphone-common.dtsi
--- a/arch/arm/boot/dts/motorola-mapphone-common.dtsi
+++ b/arch/arm/boot/dts/motorola-mapphone-common.dtsi
@@ -182,6 +182,14 @@ vibrator {
 		pwm-names = "enable", "direction";
 		direction-duty-cycle-ns = <10000000>;
 	};
+
+	backlight: backlight {
+		compatible = "led-backlight";
+
+		leds = <&backlight_led>;
+		brightness-levels = <31 63 95 127 159 191 223 255>;
+		default-brightness-level = <6>;
+	};
 };
 
 &dss {
@@ -205,6 +213,8 @@ lcd0: display {
 		vddi-supply = <&lcd_regulator>;
 		reset-gpios = <&gpio4 5 GPIO_ACTIVE_HIGH>;	/* gpio101 */
 
+		backlight = <&backlight>;
+
 		width-mm = <50>;
 		height-mm = <89>;
 
@@ -393,12 +403,11 @@ led-controller@38 {
 		ramp-up-us = <1024>;
 		ramp-down-us = <8193>;
 
-		led@0 {
+		backlight_led: led@0 {
 			reg = <0>;
 			led-sources = <2>;
 			ti,led-mode = <0>;
 			label = ":backlight";
-			linux,default-trigger = "backlight";
 		};
 
 		led@1 {
diff --git a/arch/arm/configs/omap2plus_defconfig b/arch/arm/configs/omap2plus_defconfig
--- a/arch/arm/configs/omap2plus_defconfig
+++ b/arch/arm/configs/omap2plus_defconfig
@@ -375,6 +375,7 @@ CONFIG_BACKLIGHT_GENERIC=m
 CONFIG_BACKLIGHT_PWM=m
 CONFIG_BACKLIGHT_PANDORA=m
 CONFIG_BACKLIGHT_GPIO=m
+CONFIG_BACKLIGHT_LED=m
 CONFIG_FRAMEBUFFER_CONSOLE=y
 CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
 CONFIG_LOGO=y

Pavel Machek Feb. 19, 2020, 8:53 p.m. UTC | #2

Hi!

> > 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 <[e-mail]>
> > Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
> > Acked-by: Pavel Machek <[e-mail]>
> > Reviewed-by: Daniel Thompson <[e-mail]>
> > Acked-by: Lee Jones <[e-mail]>
> > Acked-by: Tony Lindgren <[e-mail]>
> > Tested-by: Tony Lindgren <[e-mail]>
> > Signed-off-by: Pavel Machek <[e-mail]>
> > ---
> >  drivers/video/backlight/Kconfig  |   7 ++
> >  drivers/video/backlight/Makefile |   1 +
> >  drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 268 insertions(+)
> >  create mode 100644 drivers/video/backlight/led_bl.c

> > Here's the version of the driver I have. AFAICT
> > default-brightness-level handling is ok, so does not need to be
> > changed.
> > 
> > Lee, it would be easiest for me if you could apply it to your tree and
> > push, but given enough time I can push it to Linus, too.
> 
> Oh you're using quoted-printable for patches.. Got it applied now,
> and it still works. Below is also the related dts change that
> I tested with.
> 
> Feel free to pick the dts change too, naturally that should
> not be applied before the driver.
> 
> If you guys instead want me to pick these both into my fixes
> branch, just let me know and I'll do the explaining why these
> are needed as fixes. Basically we no longer have a way to enable
> the LCD backlight for droid4 manually starting with v5.6-rc1
> unlike earlier.

If you are willing to do that, it looks like good solution from my
point of view.

Thanks,
									Pavel

Tony Lindgren Feb. 19, 2020, 9:15 p.m. UTC | #3

* Pavel Machek <[e-mail]> [200219 20:54]:
> Hi!
> 
> > > 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 <[e-mail]>
> > > Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
> > > Acked-by: Pavel Machek <[e-mail]>
> > > Reviewed-by: Daniel Thompson <[e-mail]>
> > > Acked-by: Lee Jones <[e-mail]>
> > > Acked-by: Tony Lindgren <[e-mail]>
> > > Tested-by: Tony Lindgren <[e-mail]>
> > > Signed-off-by: Pavel Machek <[e-mail]>
> > > ---
> > >  drivers/video/backlight/Kconfig  |   7 ++
> > >  drivers/video/backlight/Makefile |   1 +
> > >  drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 268 insertions(+)
> > >  create mode 100644 drivers/video/backlight/led_bl.c
> 
> > > Here's the version of the driver I have. AFAICT
> > > default-brightness-level handling is ok, so does not need to be
> > > changed.
> > > 
> > > Lee, it would be easiest for me if you could apply it to your tree and
> > > push, but given enough time I can push it to Linus, too.
> > 
> > Oh you're using quoted-printable for patches.. Got it applied now,
> > and it still works. Below is also the related dts change that
> > I tested with.
> > 
> > Feel free to pick the dts change too, naturally that should
> > not be applied before the driver.
> > 
> > If you guys instead want me to pick these both into my fixes
> > branch, just let me know and I'll do the explaining why these
> > are needed as fixes. Basically we no longer have a way to enable
> > the LCD backlight for droid4 manually starting with v5.6-rc1
> > unlike earlier.
> 
> If you are willing to do that, it looks like good solution from my
> point of view.

OK. I'll apply them but won't push out yet in case Lee is already
applying the driver change..

Pavel, care to ack the dts patch?

Regards,

Tony

Sebastian Reichel Feb. 19, 2020, 11:44 p.m. UTC | #4

On Wed, Feb 19, 2020 at 11:45:40AM -0800, Tony Lindgren wrote:
> * Pavel Machek <[e-mail]> [200219 19:15]:
> > From: Tomi Valkeinen <[e-mail]>
> > 
> > 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 <[e-mail]>
> > Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
> > Acked-by: Pavel Machek <[e-mail]>
> > Reviewed-by: Daniel Thompson <[e-mail]>
> > Acked-by: Lee Jones <[e-mail]>
> > Acked-by: Tony Lindgren <[e-mail]>
> > Tested-by: Tony Lindgren <[e-mail]>
> > Signed-off-by: Pavel Machek <[e-mail]>
> > ---
> >  drivers/video/backlight/Kconfig  |   7 ++
> >  drivers/video/backlight/Makefile |   1 +
> >  drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 268 insertions(+)
> >  create mode 100644 drivers/video/backlight/led_bl.c
> > 
> > Hi!
> > 
> > Here's the version of the driver I have. AFAICT
> > default-brightness-level handling is ok, so does not need to be
> > changed.
> > 
> > Lee, it would be easiest for me if you could apply it to your tree and
> > push, but given enough time I can push it to Linus, too.
> 
> Oh you're using quoted-printable for patches.. Got it applied now,
> and it still works. Below is also the related dts change that
> I tested with.
> 
> Feel free to pick the dts change too, naturally that should
> not be applied before the driver.
> 
> If you guys instead want me to pick these both into my fixes
> branch, just let me know and I'll do the explaining why these
> are needed as fixes. Basically we no longer have a way to enable
> the LCD backlight for droid4 manually starting with v5.6-rc1
> unlike earlier.
> 
> Regards,
> 
> Tony
> 
> 8< ------------------
> From tony Mon Sep 17 00:00:00 2001
> From: Tony Lindgren <[e-mail]>
> Date: Wed, 19 Feb 2020 11:25:27 -0800
> Subject: [PATCH] ARM: dts: droid4: Configure LED backlight for lm3532
> 
> With the LED backlight changes merged, we still need the dts configured
> to have backlight working for droid4. Based on an earlier patch from
> Pavel Machek <[e-mail]>, let's configure the backlight but update
> the value range to be more usable.
> 
> We have a range of 256 register values split into 8 steps, so we can
> generate the brightness levels backwards with:
> 
> $ for i in 0 1 2 3 4 5 6 7; do echo "255 - ${i} * (256 / 8)" | bc; done
> 
> To avoid more confusion why the LCD backlight is still not on, let's
> also enable LED backlight as a loadable module for omap2plus_defconfig.
> 
> Cc: Merlijn Wajer <[e-mail]>
> Cc: Pavel Machek <[e-mail]>
> Signed-off-by: Tony Lindgren <[e-mail]>
> ---
>  arch/arm/boot/dts/motorola-mapphone-common.dtsi | 13 +++++++++++--
>  arch/arm/configs/omap2plus_defconfig            |  1 +
>  2 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/boot/dts/motorola-mapphone-common.dtsi b/arch/arm/boot/dts/motorola-mapphone-common.dtsi
> --- a/arch/arm/boot/dts/motorola-mapphone-common.dtsi
> +++ b/arch/arm/boot/dts/motorola-mapphone-common.dtsi
> @@ -182,6 +182,14 @@ vibrator {
>  		pwm-names = "enable", "direction";
>  		direction-duty-cycle-ns = <10000000>;
>  	};
> +
> +	backlight: backlight {
> +		compatible = "led-backlight";
> +
> +		leds = <&backlight_led>;
> +		brightness-levels = <31 63 95 127 159 191 223 255>;
> +		default-brightness-level = <6>;
> +	};
>  };
>  
>  &dss {
> @@ -205,6 +213,8 @@ lcd0: display {
>  		vddi-supply = <&lcd_regulator>;
>  		reset-gpios = <&gpio4 5 GPIO_ACTIVE_HIGH>;	/* gpio101 */
>  
> +		backlight = <&backlight>;
> +
>  		width-mm = <50>;
>  		height-mm = <89>;
>  
> @@ -393,12 +403,11 @@ led-controller@38 {
>  		ramp-up-us = <1024>;
>  		ramp-down-us = <8193>;
>  
> -		led@0 {
> +		backlight_led: led@0 {
>  			reg = <0>;
>  			led-sources = <2>;
>  			ti,led-mode = <0>;
>  			label = ":backlight";
> -			linux,default-trigger = "backlight";
>  		};
>  
>  		led@1 {
> diff --git a/arch/arm/configs/omap2plus_defconfig b/arch/arm/configs/omap2plus_defconfig
> --- a/arch/arm/configs/omap2plus_defconfig
> +++ b/arch/arm/configs/omap2plus_defconfig
> @@ -375,6 +375,7 @@ CONFIG_BACKLIGHT_GENERIC=m
>  CONFIG_BACKLIGHT_PWM=m
>  CONFIG_BACKLIGHT_PANDORA=m
>  CONFIG_BACKLIGHT_GPIO=m
> +CONFIG_BACKLIGHT_LED=m
>  CONFIG_FRAMEBUFFER_CONSOLE=y
>  CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
>  CONFIG_LOGO=y

Finally :)

Reviewed-by: Sebastian Reichel <[e-mail]>

-- Sebastian

Pavel Machek Feb. 19, 2020, 11:54 p.m. UTC | #5

Hi!

> > > If you guys instead want me to pick these both into my fixes
> > > branch, just let me know and I'll do the explaining why these
> > > are needed as fixes. Basically we no longer have a way to enable
> > > the LCD backlight for droid4 manually starting with v5.6-rc1
> > > unlike earlier.
> > 
> > If you are willing to do that, it looks like good solution from my
> > point of view.
> 
> OK. I'll apply them but won't push out yet in case Lee is already
> applying the driver change..
> 
> Pavel, care to ack the dts patch?

It looks okay to me (but did not test it yet).

Acked-by: Pavel Machek <[e-mail]>

Thanks,
									Pavel

Lee Jones Feb. 20, 2020, 7:48 a.m. UTC | #6

On Wed, 19 Feb 2020, Tony Lindgren wrote:

> * Pavel Machek <[e-mail]> [200219 19:15]:
> > From: Tomi Valkeinen <[e-mail]>
> > 
> > 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 <[e-mail]>
> > Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
> > Acked-by: Pavel Machek <[e-mail]>
> > Reviewed-by: Daniel Thompson <[e-mail]>
> > Acked-by: Lee Jones <[e-mail]>
> > Acked-by: Tony Lindgren <[e-mail]>
> > Tested-by: Tony Lindgren <[e-mail]>
> > Signed-off-by: Pavel Machek <[e-mail]>
> > ---
> >  drivers/video/backlight/Kconfig  |   7 ++
> >  drivers/video/backlight/Makefile |   1 +
> >  drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 268 insertions(+)
> >  create mode 100644 drivers/video/backlight/led_bl.c
> > 
> > Hi!
> > 
> > Here's the version of the driver I have. AFAICT
> > default-brightness-level handling is ok, so does not need to be
> > changed.
> > 
> > Lee, it would be easiest for me if you could apply it to your tree and
> > push, but given enough time I can push it to Linus, too.
> 
> Oh you're using quoted-printable for patches.. Got it applied now,
> and it still works. Below is also the related dts change that
> I tested with.
> 
> Feel free to pick the dts change too, naturally that should
> not be applied before the driver.
> 
> If you guys instead want me to pick these both into my fixes
> branch, just let me know and I'll do the explaining why these
> are needed as fixes. Basically we no longer have a way to enable
> the LCD backlight for droid4 manually starting with v5.6-rc1
> unlike earlier.

Please do.  You already have my Ack.

--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Guido Günther Feb. 20, 2020, 8:29 a.m. UTC | #7

Hi,
On Wed, Feb 19, 2020 at 08:14:12PM +0100, Pavel Machek wrote:
> From: Tomi Valkeinen <[e-mail]>
> 
> 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 <[e-mail]>
> Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
> Acked-by: Pavel Machek <[e-mail]>
> Reviewed-by: Daniel Thompson <[e-mail]>
> Acked-by: Lee Jones <[e-mail]>
> Acked-by: Tony Lindgren <[e-mail]>
> Tested-by: Tony Lindgren <[e-mail]>
> Signed-off-by: Pavel Machek <[e-mail]>

Tested-by: Guido Günther <[e-mail]>

Cheers,
 -- Guido

> ---
>  drivers/video/backlight/Kconfig  |   7 ++
>  drivers/video/backlight/Makefile |   1 +
>  drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 268 insertions(+)
>  create mode 100644 drivers/video/backlight/led_bl.c
> 
> Hi!
> 
> Here's the version of the driver I have. AFAICT
> default-brightness-level handling is ok, so does not need to be
> changed.
> 
> Lee, it would be easiest for me if you could apply it to your tree and
> push, but given enough time I can push it to Linus, too.
> 
> Thanks,
> 								Pavel
> 
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 403707a3e503..0093bbd0d326 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -456,6 +456,13 @@ config BACKLIGHT_RAVE_SP
>  	help
>  	  Support for backlight control on RAVE SP device.
>  
> +config BACKLIGHT_LED
> +	tristate "Generic LED based Backlight Driver"
> +	depends on LEDS_CLASS && OF
> +	help
> +	  If you have a LCD backlight adjustable by LED class driver, say Y
> +	  to enable this driver.
> +
>  endif # BACKLIGHT_CLASS_DEVICE
>  
>  endmenu
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index 6f8777037c37..0c1a1524627a 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -57,3 +57,4 @@ obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
>  obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
>  obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
>  obj-$(CONFIG_BACKLIGHT_RAVE_SP)		+= rave-sp-backlight.o
> +obj-$(CONFIG_BACKLIGHT_LED)		+= led_bl.o
> diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c
> new file mode 100644
> index 000000000000..3f66549997c8
> --- /dev/null
> +++ b/drivers/video/backlight/led_bl.c
> @@ -0,0 +1,260 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2015-2019 Texas Instruments Incorporated -  http://www.ti.com/
> + * Author: Tomi Valkeinen <[e-mail]>
> + *
> + * Based on pwm_bl.c
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +struct led_bl_data {
> +	struct device		*dev;
> +	struct backlight_device	*bl_dev;
> +	struct led_classdev	**leds;
> +	bool			enabled;
> +	int			nb_leds;
> +	unsigned int		*levels;
> +	unsigned int		default_brightness;
> +	unsigned int		max_brightness;
> +};
> +
> +static void led_bl_set_brightness(struct led_bl_data *priv, int level)
> +{
> +	int i;
> +	int bkl_brightness;
> +
> +	if (priv->levels)
> +		bkl_brightness = priv->levels[level];
> +	else
> +		bkl_brightness = level;
> +
> +	for (i = 0; i < priv->nb_leds; i++)
> +		led_set_brightness(priv->leds[i], bkl_brightness);
> +
> +	priv->enabled = true;
> +}
> +
> +static void led_bl_power_off(struct led_bl_data *priv)
> +{
> +	int i;
> +
> +	if (!priv->enabled)
> +		return;
> +
> +	for (i = 0; i < priv->nb_leds; i++)
> +		led_set_brightness(priv->leds[i], LED_OFF);
> +
> +	priv->enabled = false;
> +}
> +
> +static int led_bl_update_status(struct backlight_device *bl)
> +{
> +	struct led_bl_data *priv = bl_get_data(bl);
> +	int brightness = bl->props.brightness;
> +
> +	if (bl->props.power != FB_BLANK_UNBLANK ||
> +	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
> +	    bl->props.state & BL_CORE_FBBLANK)
> +		brightness = 0;
> +
> +	if (brightness > 0)
> +		led_bl_set_brightness(priv, brightness);
> +	else
> +		led_bl_power_off(priv);
> +
> +	return 0;
> +}
> +
> +static const struct backlight_ops led_bl_ops = {
> +	.update_status	= led_bl_update_status,
> +};
> +
> +static int led_bl_get_leds(struct device *dev,
> +			   struct led_bl_data *priv)
> +{
> +	int i, nb_leds, ret;
> +	struct device_node *node = dev->of_node;
> +	struct led_classdev **leds;
> +	unsigned int max_brightness;
> +	unsigned int default_brightness;
> +
> +	ret = of_count_phandle_with_args(node, "leds", NULL);
> +	if (ret < 0) {
> +		dev_err(dev, "Unable to get led count\n");
> +		return -EINVAL;
> +	}
> +
> +	nb_leds = ret;
> +	if (nb_leds < 1) {
> +		dev_err(dev, "At least one LED must be specified!\n");
> +		return -EINVAL;
> +	}
> +
> +	leds = devm_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,
> +			    GFP_KERNEL);
> +	if (!leds)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < nb_leds; i++) {
> +		leds[i] = devm_of_led_get(dev, i);
> +		if (IS_ERR(leds[i]))
> +			return PTR_ERR(leds[i]);
> +	}
> +
> +	/* check that the LEDs all have the same brightness range */
> +	max_brightness = leds[0]->max_brightness;
> +	for (i = 1; i < nb_leds; i++) {
> +		if (max_brightness != leds[i]->max_brightness) {
> +			dev_err(dev, "LEDs must have identical ranges\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	/* get the default brightness from the first LED from the list */
> +	default_brightness = leds[0]->brightness;
> +
> +	priv->nb_leds = nb_leds;
> +	priv->leds = leds;
> +	priv->max_brightness = max_brightness;
> +	priv->default_brightness = default_brightness;
> +
> +	return 0;
> +}
> +
> +static int led_bl_parse_levels(struct device *dev,
> +			   struct led_bl_data *priv)
> +{
> +	struct device_node *node = dev->of_node;
> +	int num_levels;
> +	u32 value;
> +	int ret;
> +
> +	if (!node)
> +		return -ENODEV;
> +
> +	num_levels = of_property_count_u32_elems(node, "brightness-levels");
> +	if (num_levels > 1) {
> +		int i;
> +		unsigned int db;
> +		u32 *levels = NULL;
> +
> +		levels = devm_kzalloc(dev, sizeof(u32) * num_levels,
> +				      GFP_KERNEL);
> +		if (!levels)
> +			return -ENOMEM;
> +
> +		ret = of_property_read_u32_array(node, "brightness-levels",
> +						levels,
> +						num_levels);
> +		if (ret < 0)
> +			return ret;
> +
> +		/*
> +		 * Try to map actual LED brightness to backlight brightness
> +		 * level
> +		 */
> +		db = priv->default_brightness;
> +		for (i = 0 ; i < num_levels; i++) {
> +			if ((i && db > levels[i-1]) && db <= levels[i])
> +				break;
> +		}
> +		priv->default_brightness = i;
> +		priv->max_brightness = num_levels - 1;
> +		priv->levels = levels;
> +	} else if (num_levels >= 0)
> +		dev_warn(dev, "Not enough levels defined\n");
> +
> +	ret = of_property_read_u32(node, "default-brightness-level", &value);
> +	if (!ret && value <= priv->max_brightness)
> +		priv->default_brightness = value;
> +	else if (!ret  && value > priv->max_brightness)
> +		dev_warn(dev, "Invalid default brightness. Ignoring it\n");
> +
> +	return 0;
> +}
> +
> +static int led_bl_probe(struct platform_device *pdev)
> +{
> +	struct backlight_properties props;
> +	struct led_bl_data *priv;
> +	int ret, i;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	priv->dev = &pdev->dev;
> +
> +	ret = led_bl_get_leds(&pdev->dev, priv);
> +	if (ret)
> +		return ret;
> +
> +	ret = led_bl_parse_levels(&pdev->dev, priv);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to parse DT data\n");
> +		return ret;
> +	}
> +
> +	memset(&props, 0, sizeof(struct backlight_properties));
> +	props.type = BACKLIGHT_RAW;
> +	props.max_brightness = priv->max_brightness;
> +	props.brightness = priv->default_brightness;
> +	props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN :
> +		      FB_BLANK_UNBLANK;
> +	priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
> +			&pdev->dev, priv, &led_bl_ops, &props);
> +	if (IS_ERR(priv->bl_dev)) {
> +		dev_err(&pdev->dev, "Failed to register backlight\n");
> +		return PTR_ERR(priv->bl_dev);
> +	}
> +
> +	for (i = 0; i < priv->nb_leds; i++)
> +		led_sysfs_disable(priv->leds[i]);
> +
> +	backlight_update_status(priv->bl_dev);
> +
> +	return 0;
> +}
> +
> +static int led_bl_remove(struct platform_device *pdev)
> +{
> +	struct led_bl_data *priv = platform_get_drvdata(pdev);
> +	struct backlight_device *bl = priv->bl_dev;
> +	int i;
> +
> +	backlight_device_unregister(bl);
> +
> +	led_bl_power_off(priv);
> +	for (i = 0; i < priv->nb_leds; i++)
> +		led_sysfs_enable(priv->leds[i]);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id led_bl_of_match[] = {
> +	{ .compatible = "led-backlight" },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, led_bl_of_match);
> +
> +static struct platform_driver led_bl_driver = {
> +	.driver		= {
> +		.name		= "led-backlight",
> +		.of_match_table	= of_match_ptr(led_bl_of_match),
> +	},
> +	.probe		= led_bl_probe,
> +	.remove		= led_bl_remove,
> +};
> +
> +module_platform_driver(led_bl_driver);
> +
> +MODULE_DESCRIPTION("LED based Backlight Driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:led-backlight");
> -- 
> 2.11.0

Tony Lindgren Feb. 20, 2020, 2:54 p.m. UTC | #8

* Sebastian Reichel <[e-mail]> [200219 23:45]:
> Finally :)
> 
> Reviewed-by: Sebastian Reichel <[e-mail]>

Yeah thanks for your persistent effort on getting this working :)

Regards,

Tony

Tony Lindgren Feb. 20, 2020, 3:09 p.m. UTC | #9

* Lee Jones <[e-mail]> [200220 07:49]:
> On Wed, 19 Feb 2020, Tony Lindgren wrote:
> 
> > * Pavel Machek <[e-mail]> [200219 19:15]:
> > > From: Tomi Valkeinen <[e-mail]>
> > > 
> > > 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 <[e-mail]>
> > > Signed-off-by: Jean-Jacques Hiblot <[e-mail]>
> > > Acked-by: Pavel Machek <[e-mail]>
> > > Reviewed-by: Daniel Thompson <[e-mail]>
> > > Acked-by: Lee Jones <[e-mail]>
> > > Acked-by: Tony Lindgren <[e-mail]>
> > > Tested-by: Tony Lindgren <[e-mail]>
> > > Signed-off-by: Pavel Machek <[e-mail]>
> > > ---
> > >  drivers/video/backlight/Kconfig  |   7 ++
> > >  drivers/video/backlight/Makefile |   1 +
> > >  drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 268 insertions(+)
> > >  create mode 100644 drivers/video/backlight/led_bl.c
> > > 
> > > Hi!
> > > 
> > > Here's the version of the driver I have. AFAICT
> > > default-brightness-level handling is ok, so does not need to be
> > > changed.
> > > 
> > > Lee, it would be easiest for me if you could apply it to your tree and
> > > push, but given enough time I can push it to Linus, too.
> > 
> > Oh you're using quoted-printable for patches.. Got it applied now,
> > and it still works. Below is also the related dts change that
> > I tested with.
> > 
> > Feel free to pick the dts change too, naturally that should
> > not be applied before the driver.
> > 
> > If you guys instead want me to pick these both into my fixes
> > branch, just let me know and I'll do the explaining why these
> > are needed as fixes. Basically we no longer have a way to enable
> > the LCD backlight for droid4 manually starting with v5.6-rc1
> > unlike earlier.
> 
> Please do.  You already have my Ack.

OK pushed out these two patches in omap-for-v5.6/droid4-lcd-fix.

Thanks,

Tony

Pavel Machek Feb. 20, 2020, 11:41 p.m. UTC | #10

Hi!

> > 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.
> 
> Tested-by: Guido Günther <[e-mail]>

Thanks for testing!

I noticed blog post about using Librem 5 torch. Unfortunately, it used
very strange/non-standard interface, first using LED as a GPIO to
enable LED controller, then direct i2c access. That is not acceptable
interface for mainline, and it would be better not to advertise such
code, as it will likely become broken in future.

https://puri.sm/posts/easy-librem-5-app-development-flashlight/

Best regards,
									Pavel

Guido Günther Aug. 14, 2020, 5:23 p.m. UTC | #11

Hi Pavel,
On Fri, Feb 21, 2020 at 12:41:51AM +0100, Pavel Machek wrote:
> Hi!
> 
> > > 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.
> > 
> > Tested-by: Guido Günther <[e-mail]>
> 
> Thanks for testing!
> 
> I noticed blog post about using Librem 5 torch. Unfortunately, it used
> very strange/non-standard interface, first using LED as a GPIO to
> enable LED controller, then direct i2c access. That is not acceptable
> interface for mainline, and it would be better not to advertise such
> code, as it will likely become broken in future.

I agree, there's a driver for the lm3560 in media/ but how would one
expose the torch part as a LED? It seems you hit something similar in

    https://lkml.org/lkml/2018/5/6/30

I also couldn't find an in tree driver that registers a flashlight
as a v4l subdev. Did i miss that?

Cheers,
 -- Guido

Pavel Machek Aug. 23, 2020, 9:22 p.m. UTC | #12

Hi!

> > > > 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.
> > > 
> > > Tested-by: Guido Günther <[e-mail]>
> > 
> > Thanks for testing!
> > 
> > I noticed blog post about using Librem 5 torch. Unfortunately, it used
> > very strange/non-standard interface, first using LED as a GPIO to
> > enable LED controller, then direct i2c access. That is not acceptable
> > interface for mainline, and it would be better not to advertise such
> > code, as it will likely become broken in future.
> 
> I agree, there's a driver for the lm3560 in media/ but how would one
> expose the torch part as a LED? It seems you hit something similar in
> 
>     https://lkml.org/lkml/2018/5/6/30

(Actually, I might have been wrong in that comment).

> I also couldn't find an in tree driver that registers a flashlight
> as a v4l subdev. Did i miss that?

You should get interface similar to this:

https://wiki.postmarketos.org/wiki/PINE64_PinePhone_(pine64-pinephone)

and the driver to enable that should already be in the mainline:

drivers/leds/leds-sgm3140.c

Best regards and good luck,
									Pavel

Patch

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 403707a3e503..0093bbd0d326 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -456,6 +456,13 @@  config BACKLIGHT_RAVE_SP
 	help
 	  Support for backlight control on RAVE SP device.
 
+config BACKLIGHT_LED
+	tristate "Generic LED based Backlight Driver"
+	depends on LEDS_CLASS && OF
+	help
+	  If you have a LCD backlight adjustable by LED class driver, say Y
+	  to enable this driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endmenu
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 6f8777037c37..0c1a1524627a 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -57,3 +57,4 @@  obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
 obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
 obj-$(CONFIG_BACKLIGHT_RAVE_SP)		+= rave-sp-backlight.o
+obj-$(CONFIG_BACKLIGHT_LED)		+= led_bl.o
diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c
new file mode 100644
index 000000000000..3f66549997c8
--- /dev/null
+++ b/drivers/video/backlight/led_bl.c
@@ -0,0 +1,260 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Texas Instruments Incorporated -  http://www.ti.com/
+ * Author: Tomi Valkeinen <[e-mail]>
+ *
+ * Based on pwm_bl.c
+ */
+
+#include <linux/backlight.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+struct led_bl_data {
+	struct device		*dev;
+	struct backlight_device	*bl_dev;
+	struct led_classdev	**leds;
+	bool			enabled;
+	int			nb_leds;
+	unsigned int		*levels;
+	unsigned int		default_brightness;
+	unsigned int		max_brightness;
+};
+
+static void led_bl_set_brightness(struct led_bl_data *priv, int level)
+{
+	int i;
+	int bkl_brightness;
+
+	if (priv->levels)
+		bkl_brightness = priv->levels[level];
+	else
+		bkl_brightness = level;
+
+	for (i = 0; i < priv->nb_leds; i++)
+		led_set_brightness(priv->leds[i], bkl_brightness);
+
+	priv->enabled = true;
+}
+
+static void led_bl_power_off(struct led_bl_data *priv)
+{
+	int i;
+
+	if (!priv->enabled)
+		return;
+
+	for (i = 0; i < priv->nb_leds; i++)
+		led_set_brightness(priv->leds[i], LED_OFF);
+
+	priv->enabled = false;
+}
+
+static int led_bl_update_status(struct backlight_device *bl)
+{
+	struct led_bl_data *priv = bl_get_data(bl);
+	int brightness = bl->props.brightness;
+
+	if (bl->props.power != FB_BLANK_UNBLANK ||
+	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
+	    bl->props.state & BL_CORE_FBBLANK)
+		brightness = 0;
+
+	if (brightness > 0)
+		led_bl_set_brightness(priv, brightness);
+	else
+		led_bl_power_off(priv);
+
+	return 0;
+}
+
+static const struct backlight_ops led_bl_ops = {
+	.update_status	= led_bl_update_status,
+};
+
+static int led_bl_get_leds(struct device *dev,
+			   struct led_bl_data *priv)
+{
+	int i, nb_leds, ret;
+	struct device_node *node = dev->of_node;
+	struct led_classdev **leds;
+	unsigned int max_brightness;
+	unsigned int default_brightness;
+
+	ret = of_count_phandle_with_args(node, "leds", NULL);
+	if (ret < 0) {
+		dev_err(dev, "Unable to get led count\n");
+		return -EINVAL;
+	}
+
+	nb_leds = ret;
+	if (nb_leds < 1) {
+		dev_err(dev, "At least one LED must be specified!\n");
+		return -EINVAL;
+	}
+
+	leds = devm_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,
+			    GFP_KERNEL);
+	if (!leds)
+		return -ENOMEM;
+
+	for (i = 0; i < nb_leds; i++) {
+		leds[i] = devm_of_led_get(dev, i);
+		if (IS_ERR(leds[i]))
+			return PTR_ERR(leds[i]);
+	}
+
+	/* check that the LEDs all have the same brightness range */
+	max_brightness = leds[0]->max_brightness;
+	for (i = 1; i < nb_leds; i++) {
+		if (max_brightness != leds[i]->max_brightness) {
+			dev_err(dev, "LEDs must have identical ranges\n");
+			return -EINVAL;
+		}
+	}
+
+	/* get the default brightness from the first LED from the list */
+	default_brightness = leds[0]->brightness;
+
+	priv->nb_leds = nb_leds;
+	priv->leds = leds;
+	priv->max_brightness = max_brightness;
+	priv->default_brightness = default_brightness;
+
+	return 0;
+}
+
+static int led_bl_parse_levels(struct device *dev,
+			   struct led_bl_data *priv)
+{
+	struct device_node *node = dev->of_node;
+	int num_levels;
+	u32 value;
+	int ret;
+
+	if (!node)
+		return -ENODEV;
+
+	num_levels = of_property_count_u32_elems(node, "brightness-levels");
+	if (num_levels > 1) {
+		int i;
+		unsigned int db;
+		u32 *levels = NULL;
+
+		levels = devm_kzalloc(dev, sizeof(u32) * num_levels,
+				      GFP_KERNEL);
+		if (!levels)
+			return -ENOMEM;
+
+		ret = of_property_read_u32_array(node, "brightness-levels",
+						levels,
+						num_levels);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * Try to map actual LED brightness to backlight brightness
+		 * level
+		 */
+		db = priv->default_brightness;
+		for (i = 0 ; i < num_levels; i++) {
+			if ((i && db > levels[i-1]) && db <= levels[i])
+				break;
+		}
+		priv->default_brightness = i;
+		priv->max_brightness = num_levels - 1;
+		priv->levels = levels;
+	} else if (num_levels >= 0)
+		dev_warn(dev, "Not enough levels defined\n");
+
+	ret = of_property_read_u32(node, "default-brightness-level", &value);
+	if (!ret && value <= priv->max_brightness)
+		priv->default_brightness = value;
+	else if (!ret  && value > priv->max_brightness)
+		dev_warn(dev, "Invalid default brightness. Ignoring it\n");
+
+	return 0;
+}
+
+static int led_bl_probe(struct platform_device *pdev)
+{
+	struct backlight_properties props;
+	struct led_bl_data *priv;
+	int ret, i;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->dev = &pdev->dev;
+
+	ret = led_bl_get_leds(&pdev->dev, priv);
+	if (ret)
+		return ret;
+
+	ret = led_bl_parse_levels(&pdev->dev, priv);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to parse DT data\n");
+		return ret;
+	}
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = priv->max_brightness;
+	props.brightness = priv->default_brightness;
+	props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN :
+		      FB_BLANK_UNBLANK;
+	priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
+			&pdev->dev, priv, &led_bl_ops, &props);
+	if (IS_ERR(priv->bl_dev)) {
+		dev_err(&pdev->dev, "Failed to register backlight\n");
+		return PTR_ERR(priv->bl_dev);
+	}
+
+	for (i = 0; i < priv->nb_leds; i++)
+		led_sysfs_disable(priv->leds[i]);
+
+	backlight_update_status(priv->bl_dev);
+
+	return 0;
+}
+
+static int led_bl_remove(struct platform_device *pdev)
+{
+	struct led_bl_data *priv = platform_get_drvdata(pdev);
+	struct backlight_device *bl = priv->bl_dev;
+	int i;
+
+	backlight_device_unregister(bl);
+
+	led_bl_power_off(priv);
+	for (i = 0; i < priv->nb_leds; i++)
+		led_sysfs_enable(priv->leds[i]);
+
+	return 0;
+}
+
+static const struct of_device_id led_bl_of_match[] = {
+	{ .compatible = "led-backlight" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, led_bl_of_match);
+
+static struct platform_driver led_bl_driver = {
+	.driver		= {
+		.name		= "led-backlight",
+		.of_match_table	= of_match_ptr(led_bl_of_match),
+	},
+	.probe		= led_bl_probe,
+	.remove		= led_bl_remove,
+};
+
+module_platform_driver(led_bl_driver);
+
+MODULE_DESCRIPTION("LED based Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:led-backlight");