Add driver for the Kinetic KTD2801 backlight driver.
Signed-off-by: Duje Mihanović <[email protected]>
---
Shared ExpressWire handling code and preemption watchdogs haven't been
implemented in this version as my questions regarding these two weren't
answered.
---
MAINTAINERS | 6 ++
drivers/video/backlight/Kconfig | 7 ++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/ktd2801-backlight.c | 149 ++++++++++++++++++++++++++++
4 files changed, 163 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index a7c4cf8201e0..1e25d760f312 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11884,6 +11884,12 @@ S: Maintained
F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml
F: drivers/video/backlight/ktd253-backlight.c
+KTD2801 BACKLIGHT DRIVER
+M: Duje Mihanović <[email protected]>
+S: Maintained
+F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml
+F: drivers/video/backlight/ktd2801-backlight.c
+
KTEST
M: Steven Rostedt <[email protected]>
M: John Hawley <[email protected]>
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 51387b1ef012..a2b268293345 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -183,6 +183,13 @@ 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
+ 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/Makefile b/drivers/video/backlight/Makefile
index f72e1c3c59e9..b33b647f31ca 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -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
diff --git a/drivers/video/backlight/ktd2801-backlight.c b/drivers/video/backlight/ktd2801-backlight.c
new file mode 100644
index 000000000000..bbcb2e2059a2
--- /dev/null
+++ b/drivers/video/backlight/ktd2801-backlight.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of.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_LOW_BIT_HIGH_TIME_US 5
+#define KTD2801_LOW_BIT_LOW_TIME_US (4 * KTD2801_HIGH_BIT_LOW_TIME_US)
+#define KTD2801_HIGH_BIT_LOW_TIME_US 5
+#define KTD2801_HIGH_BIT_HIGH_TIME_US (4 * KTD2801_HIGH_BIT_LOW_TIME_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
+
+struct ktd2801_backlight {
+ struct backlight_device *bd;
+ struct gpio_desc *gpiod;
+ 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)) {
+ gpiod_set_value(ktd2801->gpiod, 0);
+ udelay(KTD2801_PWR_DOWN_DELAY_US);
+ ktd2801->was_on = false;
+ return 0;
+ }
+
+ if (!ktd2801->was_on) {
+ gpiod_set_value(ktd2801->gpiod, 1);
+ udelay(KTD2801_EXPRESSWIRE_DETECT_DELAY_US);
+ gpiod_set_value(ktd2801->gpiod, 0);
+ udelay(KTD2801_EXPRESSWIRE_DETECT_US);
+ gpiod_set_value(ktd2801->gpiod, 1);
+ ktd2801->was_on = true;
+ }
+
+ gpiod_set_value(ktd2801->gpiod, 1);
+ udelay(KTD2801_DATA_START_US);
+
+ for (int i = 0; i < 8; i++) {
+ u8 next_bit = (brightness & 0x80) >> 7;
+
+ if (!next_bit) {
+ gpiod_set_value(ktd2801->gpiod, 0);
+ udelay(KTD2801_LOW_BIT_LOW_TIME_US);
+ gpiod_set_value(ktd2801->gpiod, 1);
+ udelay(KTD2801_LOW_BIT_HIGH_TIME_US);
+ } else {
+ gpiod_set_value(ktd2801->gpiod, 0);
+ udelay(KTD2801_HIGH_BIT_LOW_TIME_US);
+ gpiod_set_value(ktd2801->gpiod, 1);
+ udelay(KTD2801_HIGH_BIT_HIGH_TIME_US);
+ }
+ brightness <<= 1;
+ }
+ gpiod_set_value(ktd2801->gpiod, 0);
+ udelay(KTD2801_END_OF_DATA_LOW_US);
+ gpiod_set_value(ktd2801->gpiod, 1);
+ udelay(KTD2801_END_OF_DATA_HIGH_US);
+ 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;
+
+ 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->gpiod = devm_gpiod_get(dev, "ctrl", GPIOD_OUT_HIGH);
+ if (IS_ERR(ktd2801->gpiod))
+ return dev_err_probe(dev, PTR_ERR(dev),
+ "failed to get backlight GPIO");
+ gpiod_set_consumer_name(ktd2801->gpiod, 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_AUTHOR("Duje Mihanović <[email protected]>");
+MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver");
+MODULE_LICENSE("GPL");
--
2.43.0
Hi Duje,
thanks for your patch!
On Thu, Jan 18, 2024 at 6:33 PM Duje Mihanović <[email protected]> wrote:
> Add driver for the Kinetic KTD2801 backlight driver.>
> Signed-off-by: Duje Mihanović <[email protected]>
Add some commit message?
> +#include <linux/backlight.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/of.h>
I don't think you need <linux/of.h>, the compatible table works without
that (is in the device driver core).
> +/* These values have been extracted from Samsung's driver. */
> +#define KTD2801_EXPRESSWIRE_DETECT_DELAY_US 150
> +#define KTD2801_EXPRESSWIRE_DETECT_US 270
> +#define KTD2801_LOW_BIT_HIGH_TIME_US 5
> +#define KTD2801_LOW_BIT_LOW_TIME_US (4 * KTD2801_HIGH_BIT_LOW_TIME_US)
> +#define KTD2801_HIGH_BIT_LOW_TIME_US 5
> +#define KTD2801_HIGH_BIT_HIGH_TIME_US (4 * KTD2801_HIGH_BIT_LOW_TIME_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
> +
> +struct ktd2801_backlight {
> + struct backlight_device *bd;
> + struct gpio_desc *gpiod;
> + 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)) {
> + gpiod_set_value(ktd2801->gpiod, 0);
> + udelay(KTD2801_PWR_DOWN_DELAY_US);
That's 2600 us, a pretty long delay in a hard loop or delay timer!
Can you use usleep_range() instead, at least for this one?
> + for (int i = 0; i < 8; i++) {
> + u8 next_bit = (brightness & 0x80) >> 7;
I would just:
#include <linux/bits.h>
bool next_bit = !!(brightness & BIT(7));
Yours,
Linus Walleij
On Thu, Jan 18, 2024 at 06:32:39PM +0100, Duje Mihanović wrote:
> Add driver for the Kinetic KTD2801 backlight driver.
>
> Signed-off-by: Duje Mihanović <[email protected]>
>
> ---
> Shared ExpressWire handling code and preemption watchdogs haven't been
> implemented in this version as my questions regarding these two weren't
> answered.
> ---
The last mail I saw on this topic was of the "do you have any better
ideas?" variety. I (mis)read that as "unless you have any
better ideas" and didn't realize you were waiting for anything.
I didn't have any better ideas!
Daniel.
On Friday, January 19, 2024 10:02:33 AM CET Linus Walleij wrote:
> Hi Duje,
>
> thanks for your patch!
>
> On Thu, Jan 18, 2024 at 6:33 PM Duje Mihanović <[email protected]>
wrote:
> > Add driver for the Kinetic KTD2801 backlight driver.>
> > Signed-off-by: Duje Mihanović <[email protected]>
>
> Add some commit message?
Besides the usual short explanation of the hardware I'd also add a link to the
datasheet in the commit message if that's appropriate.
> > +#include <linux/backlight.h>
> > +#include <linux/delay.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/of.h>
>
> I don't think you need <linux/of.h>, the compatible table works without
> that (is in the device driver core).
Can confirm it compiles without.
> > +/* These values have been extracted from Samsung's driver. */
> > +#define KTD2801_EXPRESSWIRE_DETECT_DELAY_US 150
> > +#define KTD2801_EXPRESSWIRE_DETECT_US 270
> > +#define KTD2801_LOW_BIT_HIGH_TIME_US 5
> > +#define KTD2801_LOW_BIT_LOW_TIME_US (4 *
> > KTD2801_HIGH_BIT_LOW_TIME_US) +#define KTD2801_HIGH_BIT_LOW_TIME_US
> > 5
> > +#define KTD2801_HIGH_BIT_HIGH_TIME_US (4 *
> > KTD2801_HIGH_BIT_LOW_TIME_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
> > +
> > +struct ktd2801_backlight {
> > + struct backlight_device *bd;
> > + struct gpio_desc *gpiod;
> > + 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)) {
> > + gpiod_set_value(ktd2801->gpiod, 0);
> > + udelay(KTD2801_PWR_DOWN_DELAY_US);
>
> That's 2600 us, a pretty long delay in a hard loop or delay timer!
>
> Can you use usleep_range() instead, at least for this one?
Sounds like a good idea. Should I also make that GPIO pulldown _cansleep while
at it?
> > + for (int i = 0; i < 8; i++) {
> > + u8 next_bit = (brightness & 0x80) >> 7;
>
> I would just:
>
> #include <linux/bits.h>
>
> bool next_bit = !!(brightness & BIT(7));
Will do.
Regards,
--
Duje
On Friday, January 19, 2024 11:07:09 AM CET Daniel Thompson wrote:
> On Thu, Jan 18, 2024 at 06:32:39PM +0100, Duje Mihanović wrote:
> > Add driver for the Kinetic KTD2801 backlight driver.
> >
> > Signed-off-by: Duje Mihanović <[email protected]>
> >
> > ---
> > Shared ExpressWire handling code and preemption watchdogs haven't been
> > implemented in this version as my questions regarding these two weren't
> > answered.
> > ---
>
> The last mail I saw on this topic was of the "do you have any better
> ideas?" variety. I (mis)read that as "unless you have any
> better ideas" and didn't realize you were waiting for anything.
>
> I didn't have any better ideas!
My apologies, I'll write the library as I proposed in that email.
Regards,
--
Duje
Le 18/01/2024 à 18:32, Duje Mihanović a écrit :
> Add driver for the Kinetic KTD2801 backlight driver.
>
> Signed-off-by: Duje Mihanović <[email protected]>
>
> ---
..
> + ktd2801->gpiod = devm_gpiod_get(dev, "ctrl", GPIOD_OUT_HIGH);
> + if (IS_ERR(ktd2801->gpiod))
> + return dev_err_probe(dev, PTR_ERR(dev),
PTR_ERR(ktd2801->gpiod); ?
CJ
On Friday, January 19, 2024 6:29:21 PM CET Christophe JAILLET wrote:
> Le 18/01/2024 à 18:32, Duje Mihanović a écrit :
> > Add driver for the Kinetic KTD2801 backlight driver.
> >
> > Signed-off-by: Duje Mihanović <[email protected]>
> >
> > ---
>
> ...
>
> > + ktd2801->gpiod = devm_gpiod_get(dev, "ctrl", GPIOD_OUT_HIGH);
> > + if (IS_ERR(ktd2801->gpiod))
> > + return dev_err_probe(dev, PTR_ERR(dev),
>
> PTR_ERR(ktd2801->gpiod); ?
Good catch, I'll fix it in v3.
Regards,
--
Duje