[PATCH v1 8/9] video: backlight: add Skyworks/Analogictech AAT2870 led controller driver

[Svyatoslav Ryhel]

Add support for Skyworks AAT2870 LED Backlight Driver and Multiple LDO
Lighting Management Unit. Only backlight is supported as for now. Supported
backlight level range is from 2 to 255 with step of 1.

Tested-by: Ion Agorria <ion at agorria.com>
Signed-off-by: Svyatoslav Ryhel <clamor95 at gmail.com>
---
 drivers/video/Kconfig             |  10 +++
 drivers/video/Makefile            |   1 +
 drivers/video/aat2870_backlight.c | 132 ++++++++++++++++++++++++++++++
 3 files changed, 143 insertions(+)
 create mode 100644 drivers/video/aat2870_backlight.c

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 3551aefae89..d855883fad9 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -754,6 +754,16 @@ config ATMEL_HLCD
 	help
 	   HLCDC supports video output to an attached LCD panel.
 
+config BACKLIGHT_AAT2870
+	bool "Backlight Driver for AAT2870"
+	depends on BACKLIGHT
+	select DM_I2C
+	help
+	  Say Y to enable the backlight driver for Skyworks AAT2870 LED
+	  Backlight Driver and Multiple LDO Lighting Management Unit.
+	  Only backlight is supported as for now. Supported backlight
+	  level range is from 2 to 255 with step of 1.
+
 config BACKLIGHT_LM3532
 	bool "Backlight Driver for LM3532"
 	depends on BACKLIGHT
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index ccd791cac59..a1bf92d9099 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_$(PHASE_)BMP) += bmp.o
 
 endif
 
+obj-$(CONFIG_BACKLIGHT_AAT2870) += aat2870_backlight.o
 obj-$(CONFIG_BACKLIGHT_LM3532) += lm3532_backlight.o
 obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_backlight.o
 obj-$(CONFIG_BACKLIGHT_LP855x) += lp855x_backlight.o
diff --git a/drivers/video/aat2870_backlight.c b/drivers/video/aat2870_backlight.c
new file mode 100644
index 00000000000..209d15b3639
--- /dev/null
+++ b/drivers/video/aat2870_backlight.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2024 Svyatoslav Ryhel <clamor95 at gmail.com>
+ */
+
+#define LOG_CATEGORY UCLASS_PANEL_BACKLIGHT
+
+#include <backlight.h>
+#include <dm.h>
+#include <i2c.h>
+#include <log.h>
+#include <linux/err.h>
+#include <asm/gpio.h>
+#include <power/regulator.h>
+
+#define AAT2870_BL_MIN_BRIGHTNESS	0x01
+#define AAT2870_BL_DEF_BRIGHTNESS	0x64
+#define AAT2870_BL_MAX_BRIGHTNESS	0xff
+
+#define AAT2870_BL_CH_EN		0x00
+#define AAT2870_BLM			0x01
+
+#define AAT2870_BL_CH_ALL		0xff
+
+#define AAT2870_CURRENT_MAX		27900000
+#define AAT2870_CURRENT_STEP		900000
+
+struct aat2870_backlight_priv {
+	struct gpio_desc enable_gpio;
+
+	int channels;
+	int max_current;
+};
+
+static int aat2870_backlight_enable(struct udevice *dev)
+{
+	struct aat2870_backlight_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	dm_gpio_set_value(&priv->enable_gpio, 1);
+
+	/* Enable backlight for defined set of channels */
+	ret = dm_i2c_reg_write(dev, AAT2870_BL_CH_EN, priv->channels);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int aat2870_backlight_set_brightness(struct udevice *dev, int percent)
+{
+	struct aat2870_backlight_priv *priv = dev_get_priv(dev);
+	int brightness, ret;
+
+	if (percent == BACKLIGHT_DEFAULT)
+		percent = AAT2870_BL_DEF_BRIGHTNESS;
+
+	if (percent < AAT2870_BL_MIN_BRIGHTNESS)
+		percent = AAT2870_BL_MIN_BRIGHTNESS;
+
+	if (percent > AAT2870_BL_MAX_BRIGHTNESS)
+		percent = AAT2870_BL_MAX_BRIGHTNESS;
+
+	brightness = percent * priv->max_current;
+	brightness /= AAT2870_BL_MAX_BRIGHTNESS;
+
+	/* Set brightness level */
+	ret = dm_i2c_reg_write(dev, AAT2870_BLM, brightness);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int aat2870_backlight_of_to_plat(struct udevice *dev)
+{
+	struct aat2870_backlight_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = gpio_request_by_name(dev, "enable-gpios", 0,
+				   &priv->enable_gpio, GPIOD_IS_OUT);
+	if (ret) {
+		log_err("%s: cannot get enable-gpios (%d)\n",
+			__func__, ret);
+		return ret;
+	}
+
+	/* Backlight is one of children but has no dedicated driver */
+	ofnode backlight = ofnode_find_subnode(dev_ofnode(dev), "backlight");
+	if (ofnode_valid(backlight) && ofnode_is_enabled(backlight)) {
+		/* Number of channel is equal to bit number */
+		priv->channels = dev_read_u32_default(dev, "channels", AAT2870_BL_CH_ALL);
+		if (priv->channels != AAT2870_BL_CH_ALL)
+			priv->channels = BIT(priv->channels);
+
+		/* 450mA - 27900mA range with a 900mA step */
+		priv->max_current = dev_read_u32_default(dev, "current-max-microamp",
+							 AAT2870_CURRENT_MAX);
+		priv->max_current /= AAT2870_CURRENT_STEP;
+	}
+
+	return 0;
+}
+
+static int aat2870_backlight_probe(struct udevice *dev)
+{
+	if (device_get_uclass_id(dev->parent) != UCLASS_I2C)
+		return -EPROTONOSUPPORT;
+
+	return 0;
+}
+
+static const struct backlight_ops aat2870_backlight_ops = {
+	.enable = aat2870_backlight_enable,
+	.set_brightness = aat2870_backlight_set_brightness,
+};
+
+static const struct udevice_id aat2870_backlight_ids[] = {
+	{ .compatible = "analogictech,aat2870" },
+	{ .compatible = "skyworks,aat2870" },
+	{ }
+};
+
+U_BOOT_DRIVER(aat2870_backlight) = {
+	.name		= "aat2870_backlight",
+	.id		= UCLASS_PANEL_BACKLIGHT,
+	.of_match	= aat2870_backlight_ids,
+	.of_to_plat	= aat2870_backlight_of_to_plat,
+	.probe		= aat2870_backlight_probe,
+	.ops		= &aat2870_backlight_ops,
+	.priv_auto	= sizeof(struct aat2870_backlight_priv),
+};
-- 
2.43.0