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Message-Id: <20240118-ktd2801-v2-2-425cf32e0769@skole.hr>
Date: Thu, 18 Jan 2024 18:32:39 +0100
From: Duje Mihanović <duje.mihanovic@...le.hr>
To: Lee Jones <lee@...nel.org>,
Daniel Thompson <daniel.thompson@...aro.org>,
Jingoo Han <jingoohan1@...il.com>, Pavel Machek <pavel@....cz>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>, Helge Deller <deller@....de>
Cc: Karel Balej <balejk@...fyz.cz>, ~postmarketos/upstreaming@...ts.sr.ht,
dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-fbdev@...r.kernel.org,
Duje Mihanović <duje.mihanovic@...le.hr>
Subject: [PATCH v2 2/2] backlight: Add Kinetic KTD2801 driver
Add driver for the Kinetic KTD2801 backlight driver.
Signed-off-by: Duje Mihanović <duje.mihanovic@...le.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(+)
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@...le.hr>
+S: Maintained
+F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml
+F: drivers/video/backlight/ktd2801-backlight.c
+
KTEST
M: Steven Rostedt <rostedt@...dmis.org>
M: John Hawley <warthog9@...lescrag.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@...le.hr>");
+MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver");
+MODULE_LICENSE("GPL");
--
2.43.0
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