Merge tag 'backlight-next-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight

Pull backlight updates from Lee Jones:
 "New Drivers:
   - Add support for KTD253

  Fix-ups:
   - Add Device Tree documentation; common, kinetic,ktd253
   - Use correct header(s); tosa_lcd, tosa_bl

  Bug Fixes:
   - Fix refcount imbalance; sky81452-backlight"

* tag 'backlight-next-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  backlight: tosa_bl: Include the right header
  backlight: tosa_lcd: Include the right header
  backlight: Add Kinetic KTD253 backlight driver
  dt-bindings: backlight: Add Kinetic KTD253 bindings
  dt-bindings: backlight: Add some common backlight properties
  backlight: sky81452-backlight: Fix refcount imbalance on error

Documentation/devicetree/bindings/leds/backlight/common.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/common.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Common backlight properties
+
+maintainers:
+  - Lee Jones <lee.jones@linaro.org>
+  - Daniel Thompson <daniel.thompson@linaro.org>
+  - Jingoo Han <jingoohan1@gmail.com>
+
+description:
+  Backlight devices provide backlight for different types of graphical
+  displays. They are typically but not necessarily implemented using a white
+  LED powered by a boost converter.
+
+properties:
+  default-brightness:
+    description:
+      The default brightness that should be applied to the LED by the operating
+      system on start-up. The brightness should not exceed the brightness the
+      LED can provide.
+    $ref: /schemas/types.yaml#definitions/uint32
+
+  max-brightness:
+    description:
+      Normally the maximum brightness is determined by the hardware and this
+      property is not required. This property is used to put a software limit
+      on the brightness apart from what the driver says, as it could happen
+      that a LED can be made so bright that it gets damaged or causes damage
+      due to restrictions in a specific system, such as mounting conditions.
+    $ref: /schemas/types.yaml#definitions/uint32

Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/kinetic,ktd253.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Kinetic Technologies KTD253 one-wire backlight
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+description: |
+  The Kinetic Technologies KTD253 is a white LED backlight that is
+  controlled by a single GPIO line. If you just turn on the backlight
+  it goes to maximum backlight then you can set the level of backlight
+  using pulses on the enable wire. This is sometimes referred to as
+  "expresswire".
+
+allOf:
+  - $ref: common.yaml#
+
+properties:
+  compatible:
+    const: kinetic,ktd253
+
+  enable-gpios:
+    description: GPIO to use to enable/disable and dim the backlight.
+    maxItems: 1
+
+  default-brightness: true
+  max-brightness: true
+
+required:
+  - compatible
+  - enable-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    backlight {
+        compatible = "kinetic,ktd253";
+        enable-gpios = <&gpio2 5 GPIO_ACTIVE_HIGH>;
+        default-brightness = <13>;
+    };

MAINTAINERS

@@ -9760,6 +9760,12 @@ 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

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

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

drivers/video/backlight/ktd253-backlight.c

+// 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");

drivers/video/backlight/sky81452-backlight.c

@@ -217,6 +217,7 @@ static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
 					num_entry);
 		if (ret < 0) {
 			dev_err(dev, "led-sources node is invalid.\n");
+			of_node_put(np);
 			return ERR_PTR(-EINVAL);
 		}
 

drivers/video/backlight/tosa_bl.c

@@ -11,7 +11,7 @@
 #include <linux/device.h>
 #include <linux/spi/spi.h>
 #include <linux/i2c.h>
-#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/fb.h>
 #include <linux/backlight.h>
 #include <linux/slab.h>

drivers/video/backlight/tosa_lcd.c

@@ -12,7 +12,7 @@
 #include <linux/spi/spi.h>
 #include <linux/i2c.h>
 #include <linux/slab.h>
-#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/delay.h>
 #include <linux/lcd.h>
 #include <linux/fb.h>