| Message ID | 20240118-ktd2801-v2-2-425cf32e0769@skole.hr |
|---|---|
| State | New |
| Headers | show |
| Series | Kinetic KTD2801 backlight driver | expand |
Hi Duje, thanks for your patch! On Thu, Jan 18, 2024 at 6:33 PM Duje Mihanović <duje.mihanovic@skole.hr> wrote: > Add driver for the Kinetic KTD2801 backlight driver.> > Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr> 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 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 <duje.mihanovic@skole.hr> wrote: > > Add driver for the Kinetic KTD2801 backlight driver.> > > Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr> > > 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 <duje.mihanovic@skole.hr> > > > > --- > > 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 <duje.mihanovic@skole.hr> > > --- ... > + 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 <duje.mihanovic@skole.hr> > > > > --- > > ... > > > + 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
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 <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> 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 <duje.mihanovic@skole.hr>"); +MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver"); +MODULE_LICENSE("GPL");
Add driver for the Kinetic KTD2801 backlight driver. Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr> --- 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(+)