| Message ID | 20200812085850.2643820-3-linus.walleij@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | None | expand |
On Wed, Aug 12, 2020 at 10:58:50AM +0200, Linus Walleij wrote: > The Kinetic KTD253 backlight driver is controlled with a > single GPIO line, but still supports a range of brightness > settings by sending fast pulses on the line. > > This is based off the source code release for the Samsung > GT-S7710 mobile phone. > > Cc: Sam Ravnborg <sam@ravnborg.org> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> (although note that Sam has some patches that introduce new APIs that this driver should, but cannot yet, use) Daniel. > --- > ChangeLog v1->v2: > - Expose the 32 actual hardware levels of brightness directly > instead of using an interpolated "brightness" table. > - Use the new backlight_get_brightness() helper. > - Call backlight_update_status() in probe instead of calling > local functions to sync brightness. > - Sort includes alphabetically. > - Name the GPIO line "enable" and grab that in accordance > with the change to the DT bindings. > --- > MAINTAINERS | 6 + > drivers/video/backlight/Kconfig | 8 + > drivers/video/backlight/Makefile | 1 + > drivers/video/backlight/ktd253-backlight.c | 198 +++++++++++++++++++++ > 4 files changed, 213 insertions(+) > create mode 100644 drivers/video/backlight/ktd253-backlight.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index e627ed60d75a..4c93e3a7be11 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -9711,6 +9711,12 @@ F: Documentation/admin-guide/auxdisplay/ks0108.rst > F: drivers/auxdisplay/ks0108.c > F: include/linux/ks0108.h > > +KTD253 BACKLIGHT DRIVER > +M: Linus Walleij <linus.walleij@linaro.org> > +S: Maintained > +F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml > +F: drivers/video/backlight/ktd253-backlight.c > + > L3MDEV > M: David Ahern <dsahern@kernel.org> > L: netdev@vger.kernel.org > diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig > index 87f9fc238d28..d83c87b902c1 100644 > --- a/drivers/video/backlight/Kconfig > +++ b/drivers/video/backlight/Kconfig > @@ -182,6 +182,14 @@ config BACKLIGHT_IPAQ_MICRO > computers. Say yes if you have one of the h3100/h3600/h3700 > machines. > > +config BACKLIGHT_KTD253 > + tristate "Backlight Driver for Kinetic KTD253" > + depends on GPIOLIB || COMPILE_TEST > + help > + Say y to enabled the backlight driver for the Kinetic KTD253 > + which is a 1-wire GPIO-controlled backlight found in some mobile > + phones. > + > config BACKLIGHT_LM3533 > tristate "Backlight Driver for LM3533" > depends on MFD_LM3533 > diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile > index 13463b99f1f9..685f3f1ca4df 100644 > --- a/drivers/video/backlight/Makefile > +++ b/drivers/video/backlight/Makefile > @@ -35,6 +35,7 @@ obj-$(CONFIG_BACKLIGHT_GPIO) += gpio_backlight.o > obj-$(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_LM3533) += lm3533_bl.o > obj-$(CONFIG_BACKLIGHT_LM3630A) += lm3630a_bl.o > obj-$(CONFIG_BACKLIGHT_LM3639) += lm3639_bl.o > diff --git a/drivers/video/backlight/ktd253-backlight.c b/drivers/video/backlight/ktd253-backlight.c > new file mode 100644 > index 000000000000..e3fee3f1f582 > --- /dev/null > +++ b/drivers/video/backlight/ktd253-backlight.c > @@ -0,0 +1,198 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Backlight driver for the Kinetic KTD253 > + * Based on code and know-how from the Samsung GT-S7710 > + * Gareth Phillips <gareth.phillips@samsung.com> > + */ > +#include <linux/backlight.h> > +#include <linux/delay.h> > +#include <linux/err.h> > +#include <linux/fb.h> > +#include <linux/gpio/consumer.h> > +#include <linux/init.h> > +#include <linux/kernel.h> > +#include <linux/limits.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/property.h> > +#include <linux/slab.h> > + > +/* Current ratio is n/32 from 1/32 to 32/32 */ > +#define KTD253_MIN_RATIO 1 > +#define KTD253_MAX_RATIO 32 > +#define KTD253_DEFAULT_RATIO 13 > + > +#define KTD253_T_LOW_NS (200 + 10) /* Additional 10ns as safety factor */ > +#define KTD253_T_HIGH_NS (200 + 10) /* Additional 10ns as safety factor */ > +#define KTD253_T_OFF_MS 3 > + > +struct ktd253_backlight { > + struct device *dev; > + struct backlight_device *bl; > + struct gpio_desc *gpiod; > + u16 ratio; > +}; > + > +static int ktd253_backlight_update_status(struct backlight_device *bl) > +{ > + struct ktd253_backlight *ktd253 = bl_get_data(bl); > + int brightness = backlight_get_brightness(bl); > + u16 target_ratio; > + u16 current_ratio = ktd253->ratio; > + unsigned long flags; > + > + dev_dbg(ktd253->dev, "new brightness/ratio: %d/32\n", brightness); > + > + target_ratio = brightness; > + > + if (target_ratio == current_ratio) > + /* This is already right */ > + return 0; > + > + if (target_ratio == 0) { > + gpiod_set_value_cansleep(ktd253->gpiod, 0); > + /* > + * We need to keep the GPIO low for at least this long > + * to actually switch the KTD253 off. > + */ > + msleep(KTD253_T_OFF_MS); > + ktd253->ratio = 0; > + return 0; > + } > + > + if (current_ratio == 0) { > + gpiod_set_value_cansleep(ktd253->gpiod, 1); > + ndelay(KTD253_T_HIGH_NS); > + /* We always fall back to this when we power on */ > + current_ratio = KTD253_MAX_RATIO; > + } > + > + /* > + * WARNING: > + * The loop to set the correct current level is performed > + * with interrupts disabled as it is timing critical. > + * The maximum number of cycles of the loop is 32 > + * so the time taken will be (T_LOW_NS + T_HIGH_NS + loop_time) * 32, > + */ > + local_irq_save(flags); > + while (current_ratio != target_ratio) { > + /* > + * These GPIO operations absolutely can NOT sleep so no > + * _cansleep suffixes, and no using GPIO expanders on > + * slow buses for this! > + */ > + gpiod_set_value(ktd253->gpiod, 0); > + ndelay(KTD253_T_LOW_NS); > + gpiod_set_value(ktd253->gpiod, 1); > + ndelay(KTD253_T_HIGH_NS); > + /* After 1/32 we loop back to 32/32 */ > + if (current_ratio == KTD253_MIN_RATIO) > + current_ratio = KTD253_MAX_RATIO; > + else > + current_ratio--; > + } > + local_irq_restore(flags); > + ktd253->ratio = current_ratio; > + > + dev_dbg(ktd253->dev, "new ratio set to %d/32\n", target_ratio); > + > + return 0; > +} > + > +static const struct backlight_ops ktd253_backlight_ops = { > + .options = BL_CORE_SUSPENDRESUME, > + .update_status = ktd253_backlight_update_status, > +}; > + > +static int ktd253_backlight_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct backlight_device *bl; > + struct ktd253_backlight *ktd253; > + u32 max_brightness; > + u32 brightness; > + int ret; > + > + ktd253 = devm_kzalloc(dev, sizeof(*ktd253), GFP_KERNEL); > + if (!ktd253) > + return -ENOMEM; > + ktd253->dev = dev; > + > + ret = device_property_read_u32(dev, "max-brightness", &max_brightness); > + if (ret) > + max_brightness = KTD253_MAX_RATIO; > + if (max_brightness > KTD253_MAX_RATIO) { > + /* Clamp brightness to hardware max */ > + dev_err(dev, "illegal max brightness specified\n"); > + max_brightness = KTD253_MAX_RATIO; > + } > + > + ret = device_property_read_u32(dev, "default-brightness", &brightness); > + if (ret) > + brightness = KTD253_DEFAULT_RATIO; > + if (brightness > max_brightness) { > + /* Clamp default brightness to max brightness */ > + dev_err(dev, "default brightness exceeds max brightness\n"); > + brightness = max_brightness; > + } > + > + if (brightness) > + /* This will be the default ratio when the KTD253 is enabled */ > + ktd253->ratio = KTD253_MAX_RATIO; > + else > + ktd253->ratio = 0; > + > + ktd253->gpiod = devm_gpiod_get(dev, "enable", > + brightness ? GPIOD_OUT_HIGH : > + GPIOD_OUT_LOW); > + if (IS_ERR(ktd253->gpiod)) { > + ret = PTR_ERR(ktd253->gpiod); > + if (ret != -EPROBE_DEFER) > + dev_err(dev, "gpio line missing or invalid.\n"); > + return ret; > + } > + gpiod_set_consumer_name(ktd253->gpiod, dev_name(dev)); > + > + bl = devm_backlight_device_register(dev, dev_name(dev), dev, ktd253, > + &ktd253_backlight_ops, NULL); > + if (IS_ERR(bl)) { > + dev_err(dev, "failed to register backlight\n"); > + return PTR_ERR(bl); > + } > + bl->props.max_brightness = max_brightness; > + /* When we just enable the GPIO line we set max brightness */ > + if (brightness) { > + bl->props.brightness = brightness; > + bl->props.power = FB_BLANK_UNBLANK; > + } else { > + bl->props.brightness = 0; > + bl->props.power = FB_BLANK_POWERDOWN; > + } > + > + ktd253->bl = bl; > + platform_set_drvdata(pdev, bl); > + backlight_update_status(bl); > + > + return 0; > +} > + > +static const struct of_device_id ktd253_backlight_of_match[] = { > + { .compatible = "kinetic,ktd253" }, > + { /* sentinel */ } > +}; > +MODULE_DEVICE_TABLE(of, ktd253_backlight_of_match); > + > +static struct platform_driver ktd253_backlight_driver = { > + .driver = { > + .name = "ktd253-backlight", > + .of_match_table = ktd253_backlight_of_match, > + }, > + .probe = ktd253_backlight_probe, > +}; > +module_platform_driver(ktd253_backlight_driver); > + > +MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>"); > +MODULE_DESCRIPTION("Kinetic KTD253 Backlight Driver"); > +MODULE_LICENSE("GPL"); > +MODULE_ALIAS("platform:ktd253-backlight"); > -- > 2.26.2 > _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
diff --git a/MAINTAINERS b/MAINTAINERS index e627ed60d75a..4c93e3a7be11 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9711,6 +9711,12 @@ F: Documentation/admin-guide/auxdisplay/ks0108.rst F: drivers/auxdisplay/ks0108.c F: include/linux/ks0108.h +KTD253 BACKLIGHT DRIVER +M: Linus Walleij <linus.walleij@linaro.org> +S: Maintained +F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml +F: drivers/video/backlight/ktd253-backlight.c + L3MDEV M: David Ahern <dsahern@kernel.org> L: netdev@vger.kernel.org diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index 87f9fc238d28..d83c87b902c1 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -182,6 +182,14 @@ config BACKLIGHT_IPAQ_MICRO computers. Say yes if you have one of the h3100/h3600/h3700 machines. +config BACKLIGHT_KTD253 + tristate "Backlight Driver for Kinetic KTD253" + depends on GPIOLIB || COMPILE_TEST + help + Say y to enabled the backlight driver for the Kinetic KTD253 + which is a 1-wire GPIO-controlled backlight found in some mobile + phones. + config BACKLIGHT_LM3533 tristate "Backlight Driver for LM3533" depends on MFD_LM3533 diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile index 13463b99f1f9..685f3f1ca4df 100644 --- a/drivers/video/backlight/Makefile +++ b/drivers/video/backlight/Makefile @@ -35,6 +35,7 @@ obj-$(CONFIG_BACKLIGHT_GPIO) += gpio_backlight.o obj-$(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_LM3533) += lm3533_bl.o obj-$(CONFIG_BACKLIGHT_LM3630A) += lm3630a_bl.o obj-$(CONFIG_BACKLIGHT_LM3639) += lm3639_bl.o diff --git a/drivers/video/backlight/ktd253-backlight.c b/drivers/video/backlight/ktd253-backlight.c new file mode 100644 index 000000000000..e3fee3f1f582 --- /dev/null +++ b/drivers/video/backlight/ktd253-backlight.c @@ -0,0 +1,198 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Backlight driver for the Kinetic KTD253 + * Based on code and know-how from the Samsung GT-S7710 + * Gareth Phillips <gareth.phillips@samsung.com> + */ +#include <linux/backlight.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/fb.h> +#include <linux/gpio/consumer.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/limits.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/property.h> +#include <linux/slab.h> + +/* Current ratio is n/32 from 1/32 to 32/32 */ +#define KTD253_MIN_RATIO 1 +#define KTD253_MAX_RATIO 32 +#define KTD253_DEFAULT_RATIO 13 + +#define KTD253_T_LOW_NS (200 + 10) /* Additional 10ns as safety factor */ +#define KTD253_T_HIGH_NS (200 + 10) /* Additional 10ns as safety factor */ +#define KTD253_T_OFF_MS 3 + +struct ktd253_backlight { + struct device *dev; + struct backlight_device *bl; + struct gpio_desc *gpiod; + u16 ratio; +}; + +static int ktd253_backlight_update_status(struct backlight_device *bl) +{ + struct ktd253_backlight *ktd253 = bl_get_data(bl); + int brightness = backlight_get_brightness(bl); + u16 target_ratio; + u16 current_ratio = ktd253->ratio; + unsigned long flags; + + dev_dbg(ktd253->dev, "new brightness/ratio: %d/32\n", brightness); + + target_ratio = brightness; + + if (target_ratio == current_ratio) + /* This is already right */ + return 0; + + if (target_ratio == 0) { + gpiod_set_value_cansleep(ktd253->gpiod, 0); + /* + * We need to keep the GPIO low for at least this long + * to actually switch the KTD253 off. + */ + msleep(KTD253_T_OFF_MS); + ktd253->ratio = 0; + return 0; + } + + if (current_ratio == 0) { + gpiod_set_value_cansleep(ktd253->gpiod, 1); + ndelay(KTD253_T_HIGH_NS); + /* We always fall back to this when we power on */ + current_ratio = KTD253_MAX_RATIO; + } + + /* + * WARNING: + * The loop to set the correct current level is performed + * with interrupts disabled as it is timing critical. + * The maximum number of cycles of the loop is 32 + * so the time taken will be (T_LOW_NS + T_HIGH_NS + loop_time) * 32, + */ + local_irq_save(flags); + while (current_ratio != target_ratio) { + /* + * These GPIO operations absolutely can NOT sleep so no + * _cansleep suffixes, and no using GPIO expanders on + * slow buses for this! + */ + gpiod_set_value(ktd253->gpiod, 0); + ndelay(KTD253_T_LOW_NS); + gpiod_set_value(ktd253->gpiod, 1); + ndelay(KTD253_T_HIGH_NS); + /* After 1/32 we loop back to 32/32 */ + if (current_ratio == KTD253_MIN_RATIO) + current_ratio = KTD253_MAX_RATIO; + else + current_ratio--; + } + local_irq_restore(flags); + ktd253->ratio = current_ratio; + + dev_dbg(ktd253->dev, "new ratio set to %d/32\n", target_ratio); + + return 0; +} + +static const struct backlight_ops ktd253_backlight_ops = { + .options = BL_CORE_SUSPENDRESUME, + .update_status = ktd253_backlight_update_status, +}; + +static int ktd253_backlight_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct backlight_device *bl; + struct ktd253_backlight *ktd253; + u32 max_brightness; + u32 brightness; + int ret; + + ktd253 = devm_kzalloc(dev, sizeof(*ktd253), GFP_KERNEL); + if (!ktd253) + return -ENOMEM; + ktd253->dev = dev; + + ret = device_property_read_u32(dev, "max-brightness", &max_brightness); + if (ret) + max_brightness = KTD253_MAX_RATIO; + if (max_brightness > KTD253_MAX_RATIO) { + /* Clamp brightness to hardware max */ + dev_err(dev, "illegal max brightness specified\n"); + max_brightness = KTD253_MAX_RATIO; + } + + ret = device_property_read_u32(dev, "default-brightness", &brightness); + if (ret) + brightness = KTD253_DEFAULT_RATIO; + if (brightness > max_brightness) { + /* Clamp default brightness to max brightness */ + dev_err(dev, "default brightness exceeds max brightness\n"); + brightness = max_brightness; + } + + if (brightness) + /* This will be the default ratio when the KTD253 is enabled */ + ktd253->ratio = KTD253_MAX_RATIO; + else + ktd253->ratio = 0; + + ktd253->gpiod = devm_gpiod_get(dev, "enable", + brightness ? GPIOD_OUT_HIGH : + GPIOD_OUT_LOW); + if (IS_ERR(ktd253->gpiod)) { + ret = PTR_ERR(ktd253->gpiod); + if (ret != -EPROBE_DEFER) + dev_err(dev, "gpio line missing or invalid.\n"); + return ret; + } + gpiod_set_consumer_name(ktd253->gpiod, dev_name(dev)); + + bl = devm_backlight_device_register(dev, dev_name(dev), dev, ktd253, + &ktd253_backlight_ops, NULL); + if (IS_ERR(bl)) { + dev_err(dev, "failed to register backlight\n"); + return PTR_ERR(bl); + } + bl->props.max_brightness = max_brightness; + /* When we just enable the GPIO line we set max brightness */ + if (brightness) { + bl->props.brightness = brightness; + bl->props.power = FB_BLANK_UNBLANK; + } else { + bl->props.brightness = 0; + bl->props.power = FB_BLANK_POWERDOWN; + } + + ktd253->bl = bl; + platform_set_drvdata(pdev, bl); + backlight_update_status(bl); + + return 0; +} + +static const struct of_device_id ktd253_backlight_of_match[] = { + { .compatible = "kinetic,ktd253" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, ktd253_backlight_of_match); + +static struct platform_driver ktd253_backlight_driver = { + .driver = { + .name = "ktd253-backlight", + .of_match_table = ktd253_backlight_of_match, + }, + .probe = ktd253_backlight_probe, +}; +module_platform_driver(ktd253_backlight_driver); + +MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>"); +MODULE_DESCRIPTION("Kinetic KTD253 Backlight Driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ktd253-backlight");
The Kinetic KTD253 backlight driver is controlled with a single GPIO line, but still supports a range of brightness settings by sending fast pulses on the line. This is based off the source code release for the Samsung GT-S7710 mobile phone. Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- ChangeLog v1->v2: - Expose the 32 actual hardware levels of brightness directly instead of using an interpolated "brightness" table. - Use the new backlight_get_brightness() helper. - Call backlight_update_status() in probe instead of calling local functions to sync brightness. - Sort includes alphabetically. - Name the GPIO line "enable" and grab that in accordance with the change to the DT bindings. --- MAINTAINERS | 6 + drivers/video/backlight/Kconfig | 8 + drivers/video/backlight/Makefile | 1 + drivers/video/backlight/ktd253-backlight.c | 198 +++++++++++++++++++++ 4 files changed, 213 insertions(+) create mode 100644 drivers/video/backlight/ktd253-backlight.c -- 2.26.2 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel