[v3,3/3] backlight: Add Kinetic KTD2801 backlight support
Commit Message
KTD2801 is a LED backlight driver IC found in samsung,coreprimevelte.
The brightness can be set using PWM or the ExpressWire protocol. Add
support for the KTD2801.
Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
---
MAINTAINERS | 6 ++
drivers/video/backlight/Kconfig | 8 ++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/ktd2801-backlight.c | 143 ++++++++++++++++++++++++++++
4 files changed, 158 insertions(+)
Comments
On Sat, Jan 20, 2024 at 10:27 PM Duje Mihanović <duje.mihanovic@skole.hr> wrote:
> KTD2801 is a LED backlight driver IC found in samsung,coreprimevelte.
> The brightness can be set using PWM or the ExpressWire protocol. Add
> support for the KTD2801.
>
> Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
Very slim after abstracting out the library and the library
has the change I requested so:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Yours,
Linus Walleij
On Sat, Jan 20, 2024 at 10:26:45PM +0100, Duje Mihanović wrote:
> KTD2801 is a LED backlight driver IC found in samsung,coreprimevelte.
> The brightness can be set using PWM or the ExpressWire protocol. Add
> support for the KTD2801.
>
> Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
As Linus W. said, this is looking really nice now. Thanks!
Just a couple of nits below.
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 51387b1ef012..585a5a713759 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -183,6 +183,14 @@ config BACKLIGHT_KTD253
> which is a 1-wire GPIO-controlled backlight found in some mobile
> phones.
>
> +config BACKLIGHT_KTD2801
> + tristate "Backlight Driver for Kinetic KTD2801"
> + depends on GPIOLIB || COMPILE_TEST
As patch 1 feedback, seems odd for the client to be responsible for
this. It should be managed in LEDS_EXPRESSWIRE.
> + select LEDS_EXPRESSWIRE
> + help
> + Say Y to enable the backlight driver for the Kinetic KTD2801 1-wire
> + GPIO-controlled backlight found in Samsung Galaxy Core Prime VE LTE.
> +
> config BACKLIGHT_KTZ8866
> tristate "Backlight Driver for Kinetic KTZ8866"
> depends on I2C
> diff --git a/drivers/video/backlight/ktd2801-backlight.c b/drivers/video/backlight/ktd2801-backlight.c
> new file mode 100644
> index 000000000000..7b9d1a93aa71
> --- /dev/null
> +++ b/drivers/video/backlight/ktd2801-backlight.c
> @@ -0,0 +1,143 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Datasheet:
> + * https://www.kinet-ic.com/uploads/web/KTD2801/KTD2801-04b.pdf
> + */
> +#include <linux/backlight.h>
> +#include <linux/bits.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/leds-expresswire.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +
> +/* These values have been extracted from Samsung's driver. */
> +#define KTD2801_EXPRESSWIRE_DETECT_DELAY_US 150
> +#define KTD2801_EXPRESSWIRE_DETECT_US 270
> +#define KTD2801_SHORT_BITSET_US 5
> +#define KTD2801_LONG_BITSET_US (3 * KTD2801_SHORT_BITSET_US)
> +#define KTD2801_DATA_START_US 5
> +#define KTD2801_END_OF_DATA_LOW_US 10
> +#define KTD2801_END_OF_DATA_HIGH_US 350
> +#define KTD2801_PWR_DOWN_DELAY_US 2600
These are a little pointless now. They are all single use constants
and have little documentary value.
The lack of documentary value is because, for example,
KTD2801_EXPRESSWIRE_DETECT_DELAY_US, is assigned to a structure
field called detect_delay_us.
Likewise I doubt that explicitly stating that long_bitset_us is 3x
bigger than short_bitset_us is important for future driver maintainance.
> +
> +#define KTD2801_DEFAULT_BRIGHTNESS 100
> +#define KTD2801_MAX_BRIGHTNESS 255
> +
> +const struct expresswire_timing ktd2801_timing = {
> + .poweroff_us = KTD2801_PWR_DOWN_DELAY_US,
> + .detect_delay_us = KTD2801_EXPRESSWIRE_DETECT_DELAY_US,
> + .detect_us = KTD2801_EXPRESSWIRE_DETECT_US,
> + .data_start_us = KTD2801_DATA_START_US,
> + .short_bitset_us = KTD2801_SHORT_BITSET_US,
> + .long_bitset_us = KTD2801_LONG_BITSET_US,
> + .end_of_data_low_us = KTD2801_END_OF_DATA_LOW_US,
> + .end_of_data_high_us = KTD2801_END_OF_DATA_HIGH_US
> +};
> +
> +struct ktd2801_backlight {
> + struct expresswire_common_props props;
> + struct backlight_device *bd;
> + bool was_on;
> +};
> +
> +static int ktd2801_update_status(struct backlight_device *bd)
> +{
> + struct ktd2801_backlight *ktd2801 = bl_get_data(bd);
> + u8 brightness = (u8) backlight_get_brightness(bd);
> +
> + if (backlight_is_blank(bd)) {
> + expresswire_power_off(&ktd2801->props);
> + ktd2801->was_on = false;
> + return 0;
> + }
> +
> + if (!ktd2801->was_on) {
> + expresswire_enable(&ktd2801->props);
> + ktd2801->was_on = true;
> + }
> +
> + expresswire_start(&ktd2801->props);
> +
> + for (int i = 7; i >= 0; i--)
> + expresswire_set_bit(&ktd2801->props, !!(brightness & BIT(i)));
The !! is redundant... but, as previous feedback, I think writing a u8
should be in the library code anyway.
> + expresswire_end(&ktd2801->props);
> + return 0;
> +}
> +
> <snip>
Daniel.
On Monday, January 22, 2024 11:28:05 AM CET Daniel Thompson wrote:
> On Sat, Jan 20, 2024 at 10:26:45PM +0100, Duje Mihanović wrote:
> > diff --git a/drivers/video/backlight/ktd2801-backlight.c
> > b/drivers/video/backlight/ktd2801-backlight.c new file mode 100644
> > index 000000000000..7b9d1a93aa71
> > --- /dev/null
> > <snip>
> > +/* These values have been extracted from Samsung's driver. */
> > +#define KTD2801_EXPRESSWIRE_DETECT_DELAY_US 150
> > +#define KTD2801_EXPRESSWIRE_DETECT_US 270
> > +#define KTD2801_SHORT_BITSET_US 5
> > +#define KTD2801_LONG_BITSET_US (3 *
KTD2801_SHORT_BITSET_US)
> > +#define KTD2801_DATA_START_US 5
> > +#define KTD2801_END_OF_DATA_LOW_US 10
> > +#define KTD2801_END_OF_DATA_HIGH_US 350
> > +#define KTD2801_PWR_DOWN_DELAY_US 2600
>
> These are a little pointless now. They are all single use constants
> and have little documentary value.
>
> The lack of documentary value is because, for example,
> KTD2801_EXPRESSWIRE_DETECT_DELAY_US, is assigned to a structure
> field called detect_delay_us.
>
> Likewise I doubt that explicitly stating that long_bitset_us is 3x
> bigger than short_bitset_us is important for future driver maintainance.
Does this apply for ktd2692 as well?
Regards,
--
Duje
On Mon, Jan 22, 2024 at 05:24:56PM +0100, Duje Mihanović wrote:
> On Monday, January 22, 2024 11:28:05 AM CET Daniel Thompson wrote:
> > On Sat, Jan 20, 2024 at 10:26:45PM +0100, Duje Mihanović wrote:
> > > diff --git a/drivers/video/backlight/ktd2801-backlight.c
> > > b/drivers/video/backlight/ktd2801-backlight.c new file mode 100644
> > > index 000000000000..7b9d1a93aa71
> > > --- /dev/null
> > > <snip>
> > > +/* These values have been extracted from Samsung's driver. */
> > > +#define KTD2801_EXPRESSWIRE_DETECT_DELAY_US 150
> > > +#define KTD2801_EXPRESSWIRE_DETECT_US 270
> > > +#define KTD2801_SHORT_BITSET_US 5
> > > +#define KTD2801_LONG_BITSET_US (3 *
> KTD2801_SHORT_BITSET_US)
> > > +#define KTD2801_DATA_START_US 5
> > > +#define KTD2801_END_OF_DATA_LOW_US 10
> > > +#define KTD2801_END_OF_DATA_HIGH_US 350
> > > +#define KTD2801_PWR_DOWN_DELAY_US 2600
> >
> > These are a little pointless now. They are all single use constants
> > and have little documentary value.
> >
> > The lack of documentary value is because, for example,
> > KTD2801_EXPRESSWIRE_DETECT_DELAY_US, is assigned to a structure
> > field called detect_delay_us.
> >
> > Likewise I doubt that explicitly stating that long_bitset_us is 3x
> > bigger than short_bitset_us is important for future driver maintainance.
>
> Does this apply for ktd2692 as well?
I think so, yes... but I won't get in the way if you (or anyone else)
decides otherwise.
Daniel.
@@ -11891,6 +11891,12 @@ S: Maintained
F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml
F: drivers/video/backlight/ktd253-backlight.c
+KTD2801 BACKLIGHT DRIVER
+M: Duje Mihanović <duje.mihanovic@skole.hr>
+S: Maintained
+F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml
+F: drivers/video/backlight/ktd2801-backlight.c
+
KTEST
M: Steven Rostedt <rostedt@goodmis.org>
M: John Hawley <warthog9@eaglescrag.net>
@@ -183,6 +183,14 @@ config BACKLIGHT_KTD253
which is a 1-wire GPIO-controlled backlight found in some mobile
phones.
+config BACKLIGHT_KTD2801
+ tristate "Backlight Driver for Kinetic KTD2801"
+ depends on GPIOLIB || COMPILE_TEST
+ select LEDS_EXPRESSWIRE
+ help
+ Say Y to enable the backlight driver for the Kinetic KTD2801 1-wire
+ GPIO-controlled backlight found in Samsung Galaxy Core Prime VE LTE.
+
config BACKLIGHT_KTZ8866
tristate "Backlight Driver for Kinetic KTZ8866"
depends on I2C
@@ -35,6 +35,7 @@ obj-$(CONFIG_BACKLIGHT_HP680) += hp680_bl.o
obj-$(CONFIG_BACKLIGHT_HP700) += jornada720_bl.o
obj-$(CONFIG_BACKLIGHT_IPAQ_MICRO) += ipaq_micro_bl.o
obj-$(CONFIG_BACKLIGHT_KTD253) += ktd253-backlight.o
+obj-$(CONFIG_BACKLIGHT_KTD2801) += ktd2801-backlight.o
obj-$(CONFIG_BACKLIGHT_KTZ8866) += ktz8866.o
obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_bl.o
obj-$(CONFIG_BACKLIGHT_LM3630A) += lm3630a_bl.o
new file mode 100644
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Datasheet:
+ * https://www.kinet-ic.com/uploads/web/KTD2801/KTD2801-04b.pdf
+ */
+#include <linux/backlight.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/leds-expresswire.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+
+/* These values have been extracted from Samsung's driver. */
+#define KTD2801_EXPRESSWIRE_DETECT_DELAY_US 150
+#define KTD2801_EXPRESSWIRE_DETECT_US 270
+#define KTD2801_SHORT_BITSET_US 5
+#define KTD2801_LONG_BITSET_US (3 * KTD2801_SHORT_BITSET_US)
+#define KTD2801_DATA_START_US 5
+#define KTD2801_END_OF_DATA_LOW_US 10
+#define KTD2801_END_OF_DATA_HIGH_US 350
+#define KTD2801_PWR_DOWN_DELAY_US 2600
+
+#define KTD2801_DEFAULT_BRIGHTNESS 100
+#define KTD2801_MAX_BRIGHTNESS 255
+
+const struct expresswire_timing ktd2801_timing = {
+ .poweroff_us = KTD2801_PWR_DOWN_DELAY_US,
+ .detect_delay_us = KTD2801_EXPRESSWIRE_DETECT_DELAY_US,
+ .detect_us = KTD2801_EXPRESSWIRE_DETECT_US,
+ .data_start_us = KTD2801_DATA_START_US,
+ .short_bitset_us = KTD2801_SHORT_BITSET_US,
+ .long_bitset_us = KTD2801_LONG_BITSET_US,
+ .end_of_data_low_us = KTD2801_END_OF_DATA_LOW_US,
+ .end_of_data_high_us = KTD2801_END_OF_DATA_HIGH_US
+};
+
+struct ktd2801_backlight {
+ struct expresswire_common_props props;
+ struct backlight_device *bd;
+ bool was_on;
+};
+
+static int ktd2801_update_status(struct backlight_device *bd)
+{
+ struct ktd2801_backlight *ktd2801 = bl_get_data(bd);
+ u8 brightness = (u8) backlight_get_brightness(bd);
+
+ if (backlight_is_blank(bd)) {
+ expresswire_power_off(&ktd2801->props);
+ ktd2801->was_on = false;
+ return 0;
+ }
+
+ if (!ktd2801->was_on) {
+ expresswire_enable(&ktd2801->props);
+ ktd2801->was_on = true;
+ }
+
+ expresswire_start(&ktd2801->props);
+
+ for (int i = 7; i >= 0; i--)
+ expresswire_set_bit(&ktd2801->props, !!(brightness & BIT(i)));
+
+ expresswire_end(&ktd2801->props);
+ return 0;
+}
+
+static const struct backlight_ops ktd2801_backlight_ops = {
+ .update_status = ktd2801_update_status,
+};
+
+static int ktd2801_backlight_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct backlight_device *bd;
+ struct ktd2801_backlight *ktd2801;
+ u32 brightness, max_brightness;
+ int ret;
+
+ ktd2801 = devm_kzalloc(dev, sizeof(*ktd2801), GFP_KERNEL);
+ if (!ktd2801)
+ return -ENOMEM;
+ ktd2801->was_on = true;
+ ktd2801->props.timing = ktd2801_timing;
+
+ ret = device_property_read_u32(dev, "max-brightness", &max_brightness);
+ if (ret)
+ max_brightness = KTD2801_MAX_BRIGHTNESS;
+ if (max_brightness > KTD2801_MAX_BRIGHTNESS) {
+ dev_err(dev, "illegal max brightness specified\n");
+ max_brightness = KTD2801_MAX_BRIGHTNESS;
+ }
+
+ ret = device_property_read_u32(dev, "default-brightness", &brightness);
+ if (ret)
+ brightness = KTD2801_DEFAULT_BRIGHTNESS;
+ if (brightness > max_brightness) {
+ dev_err(dev, "default brightness exceeds max\n");
+ brightness = max_brightness;
+ }
+
+ ktd2801->props.ctrl_gpio = devm_gpiod_get(dev, "ctrl", GPIOD_OUT_HIGH);
+ if (IS_ERR(ktd2801->props.ctrl_gpio))
+ return dev_err_probe(dev, PTR_ERR(ktd2801->props.ctrl_gpio),
+ "failed to get backlight GPIO");
+ gpiod_set_consumer_name(ktd2801->props.ctrl_gpio, dev_name(dev));
+
+ bd = devm_backlight_device_register(dev, dev_name(dev), dev, ktd2801,
+ &ktd2801_backlight_ops, NULL);
+ if (IS_ERR(bd))
+ return dev_err_probe(dev, PTR_ERR(bd),
+ "failed to register backlight");
+
+ bd->props.max_brightness = max_brightness;
+ bd->props.brightness = brightness;
+
+ ktd2801->bd = bd;
+ platform_set_drvdata(pdev, bd);
+ backlight_update_status(bd);
+
+ return 0;
+}
+
+static const struct of_device_id ktd2801_of_match[] = {
+ { .compatible = "kinetic,ktd2801" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ktd2801_of_match);
+
+static struct platform_driver ktd2801_backlight_driver = {
+ .driver = {
+ .name = "ktd2801-backlight",
+ .of_match_table = ktd2801_of_match,
+ },
+ .probe = ktd2801_backlight_probe,
+};
+module_platform_driver(ktd2801_backlight_driver);
+
+MODULE_IMPORT_NS(EXPRESSWIRE);
+MODULE_AUTHOR("Duje Mihanović <duje.mihanovic@skole.hr>");
+MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver");
+MODULE_LICENSE("GPL");