backlight: Add Kinetic KTD2801 driver

Add driver for the Kinetic KTD2801 backlight driver.

Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>

diff --git a/MAINTAINERS b/MAINTAINERS
index 04d37e6a7d733b56f1837cad1d6d9b46d0248a6f..e9c95c7901b6021a68e111ee44e15971580a88a9 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11886,6 +11886,12 @@ 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 51387b1ef012a118c9ad54c2d19bf97d58805d65..a2b2682933459fa58d272b8229479d416167f3f6 100644 (file)
--- 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 f72e1c3c59e956a0e175429822884bef3497adcd..b33b647f31ca140ab2103cdf0f3b9b1415bcf03d 100644 (file)
--- 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 (file)
index 0000000..24a5f9e
--- /dev/null
+++ b/drivers/video/backlight/ktd2801-backlight.c
@@ -0,0 +1,151 @@
+// 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>
+
+#define EW_DELAY       150
+#define EW_DET         270
+#define LOW_BIT_HIGH   5
+#define LOW_BIT_LOW    (4 * HIGH_BIT_LOW)
+#define HIGH_BIT_LOW   5
+#define HIGH_BIT_HIGH  (4 * HIGH_BIT_LOW)
+#define DS             5
+#define EOD_L          10
+#define EOD_H          350
+#define PWR_DOWN_DELAY 2600
+
+#define KTD2801_DEFAULT_BRIGHTNESS     100
+#define KTD2801_MAX_BRIGHTNESS         255
+
+struct ktd2801_backlight {
+       struct device *dev;
+       struct backlight_device *bd;
+       struct gpio_desc *desc;
+       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->desc, 1);
+               udelay(PWR_DOWN_DELAY);
+               ktd2801->was_on = false;
+               return 0;
+       }
+
+       if (!ktd2801->was_on) {
+               gpiod_set_value(ktd2801->desc, 0);
+               udelay(EW_DELAY);
+               gpiod_set_value(ktd2801->desc, 1);
+               udelay(EW_DET);
+               gpiod_set_value(ktd2801->desc, 0);
+               ktd2801->was_on = true;
+       }
+
+       gpiod_set_value(ktd2801->desc, 0);
+       udelay(DS);
+
+       for (int i = 0; i < 8; i++) {
+               u8 next_bit = (brightness & 0x80) >> 7;
+
+               if (!next_bit) {
+                       gpiod_set_value(ktd2801->desc, 1);
+                       udelay(LOW_BIT_LOW);
+                       gpiod_set_value(ktd2801->desc, 0);
+                       udelay(LOW_BIT_HIGH);
+               } else {
+                       gpiod_set_value(ktd2801->desc, 1);
+                       udelay(HIGH_BIT_LOW);
+                       gpiod_set_value(ktd2801->desc, 0);
+                       udelay(HIGH_BIT_HIGH);
+               }
+               brightness <<= 1;
+       }
+       gpiod_set_value(ktd2801->desc, 1);
+       udelay(EOD_L);
+       gpiod_set_value(ktd2801->desc, 0);
+       udelay(EOD_H);
+       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->dev = dev;
+       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->desc = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
+       if (IS_ERR(ktd2801->desc))
+               return dev_err_probe(dev, PTR_ERR(ktd2801->desc),
+                               "failed to get backlight GPIO");
+       gpiod_set_consumer_name(ktd2801->desc, 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");
+MODULE_ALIAS("platform:ktd2801-backlight");