[PATCH 0/2] backlight: Add Awinic AW99703 driver

[PATCH 0/2] backlight: Add Awinic AW99703 driver

[Luka Panio]

The Awinic AW99703 is a high-efficiency 3-channel WLED driver with an
integrated boost converter and 11-bit brightness control over I2C,
optionally combined with a PWM input. It is used as an LCD backlight
driver in some mobile devices.

This series adds the devicetree binding and a driver for it.

Tested on the Nexphone by Nex Computers.

A board DTS using it will follow separately.

Luka Panio (2):
  dt-bindings: leds: backlight: Add Awinic AW99703 backlight
  backlight: Add Awinic AW99703 backlight driver

 .../leds/backlight/awinic,aw99703.yaml        | 131 ++++
 MAINTAINERS                                   |   6 +
 drivers/video/backlight/Kconfig               |  11 +
 drivers/video/backlight/Makefile              |   1 +
 drivers/video/backlight/aw99703.c             | 583 ++++++++++++++++++
 5 files changed, 732 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/awinic,aw99703.yaml
 create mode 100644 drivers/video/backlight/aw99703.c


base-commit: d419d682257d813f6cb7a28e42b35d0edf4ad038
-- 
2.55.0

[PATCH 1/2] dt-bindings: leds: backlight: Add Awinic AW99703 backlight

[Luka Panio]

The Awinic AW99703 is a 3-string WLED driver converter with an
integrated boost converter and 11-bit brightness control over I2C,
optionally combined with a PWM input.

Signed-off-by: Luka Panio <lukapanio@gmail.com>
---
 .../leds/backlight/awinic,aw99703.yaml        | 131 ++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/awinic,aw99703.yaml

diff --git a/Documentation/devicetree/bindings/leds/backlight/awinic,aw99703.yaml b/Documentation/devicetree/bindings/leds/backlight/awinic,aw99703.yaml
new file mode 100644
index 000000000000..62e8cc3118f2
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/awinic,aw99703.yaml
@@ -0,0 +1,131 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/awinic,aw99703.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Awinic AW99703 WLED Backlight Driver
+
+maintainers:
+  - Luka Panio <lukapanio@gmail.com>
+
+description:
+  The AW99703 is a 3-string WLED driver with an integrated boost converter
+  and 11-bit I2C (optionally PWM) brightness control.
+
+allOf:
+  - $ref: common.yaml#
+
+properties:
+  compatible:
+    const: awinic,aw99703
+
+  reg:
+    maxItems: 1
+
+  enable-gpios:
+    description: GPIO connected to the HWEN pin.
+    maxItems: 1
+
+  awinic,led-strings:
+    description: Number of enabled LED strings, starting with CH1.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 3
+    default: 3
+
+  awinic,iled-max-microamp:
+    description:
+      Full-scale current of each LED string, reached at the maximum
+      brightness code (and 100% PWM duty cycle if PWM dimming is used).
+    minimum: 4800
+    maximum: 29600
+    multipleOf: 800
+    default: 20000
+
+  awinic,ramp-on-time-us:
+    description: Current sink ramp-up time when leaving standby.
+    enum: [512, 1000, 2000, 4000, 8000, 16000, 32000, 64000, 128000,
+           256000, 512000, 1024000, 2048000, 4096000, 8192000, 16384000]
+    default: 8000
+
+  awinic,ramp-off-time-us:
+    description: Current sink ramp-down time when entering standby.
+    enum: [512, 1000, 2000, 4000, 8000, 16000, 32000, 64000, 128000,
+           256000, 512000, 1024000, 2048000, 4096000, 8192000, 16384000]
+    default: 8000
+
+  awinic,pwm-trans-time-ms:
+    description:
+      Transition time between brightness levels set by the PWM input,
+      for a change over the full duty cycle range.
+    enum: [2, 4, 8, 16, 32, 64, 128, 256]
+    default: 2
+
+  awinic,i2c-trans-time-ms:
+    description:
+      Fixed transition time between brightness levels set over I2C,
+      independent of the size of the change. When absent the brightness
+      ramps with a fixed slope of 1 us per brightness code instead.
+    enum: [128, 192, 256, 320, 384, 448, 512, 576, 640, 768, 1024, 1280,
+           1536, 2560, 4096]
+
+  awinic,ovp-microvolt:
+    description: Boost over-voltage protection threshold.
+    enum: [17500000, 24000000, 31000000, 38000000, 41500000]
+    default: 38000000
+
+  awinic,ocp-microamp:
+    description: Boost over-current protection threshold.
+    enum: [900000, 1800000, 2700000, 3400000]
+    default: 2700000
+
+  awinic,sw-freq-hz:
+    description: Boost switching frequency.
+    enum: [500000, 1000000]
+    default: 1000000
+
+  awinic,inductor-nanohenry:
+    description: Boost inductor value.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [4700, 10000]
+    default: 4700
+
+  awinic,pwm-input:
+    description: Combine the PWM input pin with the I2C brightness.
+    type: boolean
+
+  awinic,exponential-map:
+    description: Use the exponential brightness curve instead of linear.
+    type: boolean
+
+  default-brightness:
+    maximum: 2047
+
+  max-brightness:
+    maximum: 2047
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        backlight@36 {
+            compatible = "awinic,aw99703";
+            reg = <0x36>;
+            enable-gpios = <&gpio 7 GPIO_ACTIVE_HIGH>;
+            awinic,led-strings = <2>;
+            awinic,iled-max-microamp = <20000>;
+            awinic,ocp-microamp = <3400000>;
+            awinic,inductor-nanohenry = <10000>;
+        };
+    };
-- 
2.55.0

[PATCH 2/2] backlight: Add Awinic AW99703 backlight driver

[Luka Panio]

Add a driver for the Awinic AW99703 3-string WLED backlight controller.

Register values follow the AW99703 datasheet (V1.6), the structure
follows the aw99706 driver.

Signed-off-by: Luka Panio <lukapanio@gmail.com>
---
 MAINTAINERS                       |   6 +
 drivers/video/backlight/Kconfig   |  11 +
 drivers/video/backlight/Makefile  |   1 +
 drivers/video/backlight/aw99703.c | 583 ++++++++++++++++++++++++++++++
 4 files changed, 601 insertions(+)
 create mode 100644 drivers/video/backlight/aw99703.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 461a56850c84..e4168448e95c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4525,6 +4525,12 @@ L:	linux-sound@vger.kernel.org
 S:	Maintained
 F:	sound/hda/codecs/side-codecs/aw88399*
 
+AWINIC AW99703 WLED BACKLIGHT DRIVER
+M:	Luka Panio <lukapanio@gmail.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/leds/backlight/awinic,aw99703.yaml
+F:	drivers/video/backlight/aw99703.c
+
 AWINIC AW99706 WLED BACKLIGHT DRIVER
 M:	Junjie Cao <junjie.cao@linux.dev>
 S:	Maintained
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index dbf4ca23a9b6..c2494f7fa5d2 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -156,6 +156,17 @@ config BACKLIGHT_ATMEL_LCDC
 	  If in doubt, it's safe to enable this option; it doesn't kick
 	  in unless the board's description says it's wired that way.
 
+config BACKLIGHT_AW99703
+	tristate "Backlight Driver for Awinic AW99703"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you have a LCD backlight connected to the WLED outputs of an
+	  Awinic AW99703, say Y here to enable this driver.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called aw99703.
+
 config BACKLIGHT_AW99706
 	tristate "Backlight Driver for Awinic AW99706"
 	depends on I2C
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 34469711c6cd..09ec9bd71c92 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_BACKLIGHT_ADP8870)		+= adp8870_bl.o
 obj-$(CONFIG_BACKLIGHT_APPLE)		+= apple_bl.o
 obj-$(CONFIG_BACKLIGHT_APPLE_DWI)	+= apple_dwi_bl.o
 obj-$(CONFIG_BACKLIGHT_AS3711)		+= as3711_bl.o
+obj-$(CONFIG_BACKLIGHT_AW99703)		+= aw99703.o
 obj-$(CONFIG_BACKLIGHT_AW99706)		+= aw99706.o
 obj-$(CONFIG_BACKLIGHT_BD6107)		+= bd6107.o
 obj-$(CONFIG_BACKLIGHT_CGBC)		+= cgbc_bl.o
diff --git a/drivers/video/backlight/aw99703.c b/drivers/video/backlight/aw99703.c
new file mode 100644
index 000000000000..b0a46753d176
--- /dev/null
+++ b/drivers/video/backlight/aw99703.c
@@ -0,0 +1,583 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * aw99703 - Backlight driver for the AWINIC AW99703
+ *
+ * Copyright (C) 2026 Luka Panio <lukapanio@gmail.com>
+ *
+ * Register layout and init sequence based on the AW99703 datasheet (V1.6)
+ */
+#include <linux/backlight.h>
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/regmap.h>
+
+#define AW99703_MAX_BRT_LVL		2047
+#define AW99703_ID			0x03
+
+#define AW99703_REG_ID			0x00
+#define AW99703_REG_SFTRST		0x01
+#define AW99703_REG_MODE		0x02
+#define AW99703_PDIS_MASK		BIT(4)
+#define AW99703_MAP_LINEAR_MASK		BIT(2)
+#define AW99703_WORKMODE_MASK		GENMASK(1, 0)
+#define AW99703_WORKMODE_STANDBY	0
+#define AW99703_WORKMODE_BACKLIGHT	1
+#define AW99703_REG_LEDCUR		0x03
+#define AW99703_BLFS_MASK		GENMASK(7, 3)
+#define AW99703_CHANNEL_MASK		GENMASK(2, 0)
+#define AW99703_REG_BSTCTR1		0x04
+#define AW99703_SW_FREQ_MASK		BIT(5)
+#define AW99703_OVPSEL_MASK		GENMASK(4, 2)
+#define AW99703_OCPSEL_MASK		GENMASK(1, 0)
+#define AW99703_REG_BSTCTR2		0x05
+#define AW99703_IDCTSEL_MASK		BIT(6)
+#define AW99703_REG_LEDLSB		0x06
+#define AW99703_BRT_LSB_MASK		GENMASK(2, 0)
+#define AW99703_REG_LEDMSB		0x07
+#define AW99703_REG_PWM			0x08
+#define AW99703_REG_TURNCFG		0x09
+#define AW99703_RAMP_ON_MASK		GENMASK(7, 4)
+#define AW99703_RAMP_OFF_MASK		GENMASK(3, 0)
+#define AW99703_REG_TRANCFG		0x0A
+#define AW99703_PWM_TRANS_MASK		GENMASK(6, 4)
+#define AW99703_I2C_TRANS_MASK		GENMASK(3, 0)
+#define AW99703_REG_FLASH		0x0B
+#define AW99703_REG_AFHIGH		0x0C
+#define AW99703_REG_AFLOW		0x0D
+#define AW99703_REG_FLAGS1		0x0E
+#define AW99703_REG_FLAGS2		0x0F
+#define AW99703_FLAGS2_MASK		GENMASK(7, 5)
+#define AW99703_REG_FLAGS3		0x11
+#define AW99703_REG_MAX			0x69
+
+#define AW99703_HWEN_ON_DELAY_US	3500
+#define AW99703_ID_RETRIES		5
+
+#define RESV	U32_MAX
+
+/* Boost switching frequency, in Hz */
+static const u32 aw99703_sw_freq_tbl[] = { 500000, 1000000 };
+
+/* Boost over-voltage protection threshold, in uV (1xx = 41.5 V) */
+static const u32 aw99703_ovp_tbl[] = {
+	17500000, 24000000, 31000000, 38000000, 41500000, RESV, RESV, RESV
+};
+
+/* Boost over-current protection threshold, in uA */
+static const u32 aw99703_ocp_tbl[] = { 900000, 1800000, 2700000, 3400000 };
+
+/* Boost inductor, in nH */
+static const u32 aw99703_inductor_tbl[] = { 4700, 10000 };
+
+/* Current sink turn on/off ramp time, in us */
+static const u32 aw99703_ramp_tbl[] = {
+	512, 1000, 2000, 4000, 8000, 16000, 32000, 64000, 128000, 256000,
+	512000, 1024000, 2048000, 4096000, 8192000, 16384000
+};
+
+/* PWM dimming transition time, in ms */
+static const u32 aw99703_pwm_trans_tbl[] = {
+	2, 4, 8, 16, 32, 64, 128, 256
+};
+
+/* I2C dimming transition time, in ms (code 0: 1 us per brightness step) */
+static const u32 aw99703_i2c_trans_tbl[] = {
+	RESV, 128, 192, 256, 320, 384, 448, 512, 576, 640, 768, 1024, 1280,
+	1536, 2560, 4096
+};
+
+struct aw99703_dt_prop {
+	const char * const name;
+	const u32 * const lookup_tbl;
+	u8 tbl_size;
+	u32 min;
+	u32 step;
+	u8 reg;
+	u8 mask;
+	u8 def_code;
+};
+
+static const struct aw99703_dt_prop aw99703_dt_props[] = {
+	{
+		.name = "awinic,sw-freq-hz",
+		.lookup_tbl = aw99703_sw_freq_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_sw_freq_tbl),
+		.reg = AW99703_REG_BSTCTR1,
+		.mask = AW99703_SW_FREQ_MASK,
+		.def_code = 1,
+	},
+	{
+		.name = "awinic,ovp-microvolt",
+		.lookup_tbl = aw99703_ovp_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_ovp_tbl),
+		.reg = AW99703_REG_BSTCTR1,
+		.mask = AW99703_OVPSEL_MASK,
+		.def_code = 3,
+	},
+	{
+		.name = "awinic,ocp-microamp",
+		.lookup_tbl = aw99703_ocp_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_ocp_tbl),
+		.reg = AW99703_REG_BSTCTR1,
+		.mask = AW99703_OCPSEL_MASK,
+		.def_code = 2,
+	},
+	{
+		.name = "awinic,inductor-nanohenry",
+		.lookup_tbl = aw99703_inductor_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_inductor_tbl),
+		.reg = AW99703_REG_BSTCTR2,
+		.mask = AW99703_IDCTSEL_MASK,
+		.def_code = 0,
+	},
+	{
+		.name = "awinic,iled-max-microamp",
+		.min = 4800,
+		.step = 800,
+		.reg = AW99703_REG_LEDCUR,
+		.mask = AW99703_BLFS_MASK,
+		.def_code = 19,
+	},
+	{
+		.name = "awinic,ramp-on-time-us",
+		.lookup_tbl = aw99703_ramp_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_ramp_tbl),
+		.reg = AW99703_REG_TURNCFG,
+		.mask = AW99703_RAMP_ON_MASK,
+		.def_code = 4,
+	},
+	{
+		.name = "awinic,ramp-off-time-us",
+		.lookup_tbl = aw99703_ramp_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_ramp_tbl),
+		.reg = AW99703_REG_TURNCFG,
+		.mask = AW99703_RAMP_OFF_MASK,
+		.def_code = 4,
+	},
+	{
+		.name = "awinic,pwm-trans-time-ms",
+		.lookup_tbl = aw99703_pwm_trans_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_pwm_trans_tbl),
+		.reg = AW99703_REG_TRANCFG,
+		.mask = AW99703_PWM_TRANS_MASK,
+		.def_code = 0,
+	},
+	{
+		.name = "awinic,i2c-trans-time-ms",
+		.lookup_tbl = aw99703_i2c_trans_tbl,
+		.tbl_size = ARRAY_SIZE(aw99703_i2c_trans_tbl),
+		.reg = AW99703_REG_TRANCFG,
+		.mask = AW99703_I2C_TRANS_MASK,
+		.def_code = 0,
+	},
+};
+
+struct reg_init_data {
+	u8 reg;
+	u8 mask;
+	u8 val;
+};
+
+#define AW99703_INIT_TBL_SIZE	(ARRAY_SIZE(aw99703_dt_props) + 3)
+
+struct aw99703_device {
+	struct device *dev;
+	struct regmap *regmap;
+	struct backlight_device *bl_dev;
+	struct gpio_desc *hwen_gpio;
+	struct reg_init_data init_tbl[AW99703_INIT_TBL_SIZE];
+	bool bl_enable;
+};
+
+static bool aw99703_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case AW99703_REG_ID:
+	case AW99703_REG_MODE ... AW99703_REG_FLAGS2:
+	case AW99703_REG_FLAGS3:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool aw99703_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case AW99703_REG_SFTRST ... AW99703_REG_AFLOW:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool aw99703_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case AW99703_REG_FLAGS1:
+	case AW99703_REG_FLAGS2:
+	case AW99703_REG_FLAGS3:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config aw99703_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = AW99703_REG_MAX,
+	.readable_reg = aw99703_readable_reg,
+	.writeable_reg = aw99703_writeable_reg,
+	.volatile_reg = aw99703_volatile_reg,
+};
+
+static int aw99703_dt_lookup(const struct aw99703_dt_prop *prop, u32 dt_val,
+			     u8 *val)
+{
+	u32 max_code = prop->mask >> __ffs(prop->mask);
+	int i;
+
+	if (!prop->lookup_tbl) {
+		if (dt_val < prop->min || (dt_val - prop->min) % prop->step ||
+		    (dt_val - prop->min) / prop->step > max_code)
+			return -EINVAL;
+		*val = (dt_val - prop->min) / prop->step;
+		return 0;
+	}
+
+	for (i = 0; i < prop->tbl_size; i++)
+		if (prop->lookup_tbl[i] != RESV && prop->lookup_tbl[i] == dt_val)
+			break;
+
+	*val = i;
+	return i == prop->tbl_size ? -EINVAL : 0;
+}
+
+static void aw99703_dt_parse(struct aw99703_device *aw,
+			     struct backlight_properties *props)
+{
+	const struct aw99703_dt_prop *prop;
+	struct reg_init_data *init = aw->init_tbl;
+	bool exp_map;
+	u32 dt_val, strings = 3;
+	int i;
+	u8 val;
+
+	for (i = 0; i < ARRAY_SIZE(aw99703_dt_props); i++, init++) {
+		prop = &aw99703_dt_props[i];
+
+		val = prop->def_code;
+		if (!device_property_read_u32(aw->dev, prop->name, &dt_val) &&
+		    aw99703_dt_lookup(prop, dt_val, &val)) {
+			dev_warn(aw->dev, "invalid value %u for %s, using chip default\n",
+				 dt_val, prop->name);
+			val = prop->def_code;
+		}
+
+		init->reg = prop->reg;
+		init->mask = prop->mask;
+		init->val = val << __ffs(prop->mask);
+	}
+
+	device_property_read_u32(aw->dev, "awinic,led-strings", &strings);
+	if (strings < 1 || strings > 3) {
+		dev_warn(aw->dev, "invalid awinic,led-strings %u, using 3\n",
+			 strings);
+		strings = 3;
+	}
+	init->reg = AW99703_REG_LEDCUR;
+	init->mask = AW99703_CHANNEL_MASK;
+	init->val = GENMASK(strings - 1, 0);
+	init++;
+
+	init->reg = AW99703_REG_MODE;
+	init->mask = AW99703_PDIS_MASK;
+	init->val = device_property_read_bool(aw->dev, "awinic,pwm-input") ?
+		    0 : AW99703_PDIS_MASK;
+	init++;
+
+	exp_map = device_property_read_bool(aw->dev, "awinic,exponential-map");
+	init->reg = AW99703_REG_MODE;
+	init->mask = AW99703_MAP_LINEAR_MASK;
+	init->val = exp_map ? 0 : AW99703_MAP_LINEAR_MASK;
+	props->scale = exp_map ? BACKLIGHT_SCALE_NON_LINEAR :
+				 BACKLIGHT_SCALE_LINEAR;
+
+	props->max_brightness = AW99703_MAX_BRT_LVL;
+	device_property_read_u32(aw->dev, "max-brightness",
+				 &props->max_brightness);
+	if (props->max_brightness > AW99703_MAX_BRT_LVL)
+		props->max_brightness = AW99703_MAX_BRT_LVL;
+
+	props->brightness = props->max_brightness >> 1;
+	device_property_read_u32(aw->dev, "default-brightness",
+				 &props->brightness);
+	if (props->brightness > props->max_brightness)
+		props->brightness = props->max_brightness;
+}
+
+static int aw99703_hw_init(struct aw99703_device *aw)
+{
+	int ret, i;
+
+	if (aw->hwen_gpio) {
+		gpiod_set_value_cansleep(aw->hwen_gpio, 1);
+		fsleep(AW99703_HWEN_ON_DELAY_US);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(aw->init_tbl); i++) {
+		ret = regmap_update_bits(aw->regmap, aw->init_tbl[i].reg,
+					 aw->init_tbl[i].mask,
+					 aw->init_tbl[i].val);
+		if (ret) {
+			dev_err(aw->dev, "failed to write init data: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static const char * const aw99703_flags1_names[] = {
+	"over-temperature", "boost over-current", "LED3 short", "LED2 short",
+	"LED1 short", "LED3 open", "LED2 open", "LED1 open",
+};
+
+static const char * const aw99703_flags2_names[] = {
+	[5] = "flash timeout", [6] = "UVLO", [7] = "boost over-voltage",
+};
+
+static void aw99703_check_faults(struct aw99703_device *aw)
+{
+	unsigned int f1, f2;
+	unsigned long flags;
+	int bit;
+
+	if (regmap_read(aw->regmap, AW99703_REG_FLAGS1, &f1) ||
+	    regmap_read(aw->regmap, AW99703_REG_FLAGS2, &f2))
+		return;
+
+	flags = f1;
+	for_each_set_bit(bit, &flags, 8)
+		dev_warn_ratelimited(aw->dev, "fault: %s\n",
+				     aw99703_flags1_names[bit]);
+
+	flags = f2 & AW99703_FLAGS2_MASK;
+	for_each_set_bit(bit, &flags, 8)
+		dev_warn_ratelimited(aw->dev, "fault: %s\n",
+				     aw99703_flags2_names[bit]);
+}
+
+static int aw99703_update_brightness(struct aw99703_device *aw, u32 brt)
+{
+	bool enable = !!brt;
+	int ret;
+
+	ret = regmap_write(aw->regmap, AW99703_REG_LEDLSB,
+			   brt & AW99703_BRT_LSB_MASK);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(aw->regmap, AW99703_REG_LEDMSB, brt >> 3);
+	if (ret)
+		return ret;
+
+	if (aw->bl_enable == enable)
+		return 0;
+
+	ret = regmap_update_bits(aw->regmap, AW99703_REG_MODE,
+				 AW99703_WORKMODE_MASK,
+				 enable ? AW99703_WORKMODE_BACKLIGHT :
+					  AW99703_WORKMODE_STANDBY);
+	if (ret) {
+		dev_err(aw->dev, "failed to %s backlight: %d\n",
+			enable ? "enable" : "disable", ret);
+		return ret;
+	}
+
+	aw->bl_enable = enable;
+	if (enable)
+		aw99703_check_faults(aw);
+
+	return 0;
+}
+
+static int aw99703_bl_update_status(struct backlight_device *bl)
+{
+	struct aw99703_device *aw = bl_get_data(bl);
+
+	return aw99703_update_brightness(aw, backlight_get_brightness(bl));
+}
+
+static const struct backlight_ops aw99703_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = aw99703_bl_update_status,
+};
+
+static int aw99703_chip_id_read(struct aw99703_device *aw)
+{
+	unsigned int val = 0;
+	int ret = 0, i;
+
+	for (i = 0; i < AW99703_ID_RETRIES; i++) {
+		ret = regmap_read(aw->regmap, AW99703_REG_ID, &val);
+		if (!ret && val == AW99703_ID)
+			return 0;
+		fsleep(2000);
+	}
+
+	if (!ret)
+		dev_err(aw->dev, "unexpected chip id 0x%02x\n", val);
+
+	return ret ? ret : -ENODEV;
+}
+
+/*
+ * If the bootloader left the backlight on, start from its level so the
+ * handover doesn't flash the panel.
+ */
+static void aw99703_read_boot_brightness(struct aw99703_device *aw,
+					 struct backlight_properties *props)
+{
+	unsigned int mode, lsb, msb, brt;
+
+	if (regmap_read(aw->regmap, AW99703_REG_MODE, &mode) ||
+	    FIELD_GET(AW99703_WORKMODE_MASK, mode) != AW99703_WORKMODE_BACKLIGHT)
+		return;
+
+	if (regmap_read(aw->regmap, AW99703_REG_LEDLSB, &lsb) ||
+	    regmap_read(aw->regmap, AW99703_REG_LEDMSB, &msb))
+		return;
+
+	brt = (msb << 3) | (lsb & AW99703_BRT_LSB_MASK);
+	if (brt && brt <= props->max_brightness) {
+		props->brightness = brt;
+		aw->bl_enable = true;
+	}
+}
+
+static void aw99703_power_off(void *data)
+{
+	struct aw99703_device *aw = data;
+
+	aw99703_update_brightness(aw, 0);
+	gpiod_set_value_cansleep(aw->hwen_gpio, 0);
+}
+
+static int aw99703_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct backlight_properties props = {};
+	struct aw99703_device *aw;
+	int ret;
+
+	aw = devm_kzalloc(dev, sizeof(*aw), GFP_KERNEL);
+	if (!aw)
+		return -ENOMEM;
+
+	aw->dev = dev;
+	i2c_set_clientdata(client, aw);
+
+	aw->regmap = devm_regmap_init_i2c(client, &aw99703_regmap_config);
+	if (IS_ERR(aw->regmap))
+		return dev_err_probe(dev, PTR_ERR(aw->regmap),
+				     "failed to init regmap\n");
+
+	aw->hwen_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_ASIS);
+	if (IS_ERR(aw->hwen_gpio))
+		return dev_err_probe(dev, PTR_ERR(aw->hwen_gpio),
+				     "failed to get enable gpio\n");
+	if (aw->hwen_gpio) {
+		ret = gpiod_direction_output(aw->hwen_gpio, 1);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "failed to drive enable gpio\n");
+		fsleep(AW99703_HWEN_ON_DELAY_US);
+	}
+
+	ret = aw99703_chip_id_read(aw);
+	if (ret)
+		return dev_err_probe(dev, ret, "chip id check failed\n");
+
+	props.type = BACKLIGHT_RAW;
+	aw99703_dt_parse(aw, &props);
+	aw99703_read_boot_brightness(aw, &props);
+
+	ret = aw99703_hw_init(aw);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to initialize chip\n");
+
+	ret = devm_add_action_or_reset(dev, aw99703_power_off, aw);
+	if (ret)
+		return ret;
+
+	aw->bl_dev = devm_backlight_device_register(dev, "aw99703-backlight",
+						    dev, aw, &aw99703_bl_ops,
+						    &props);
+	if (IS_ERR(aw->bl_dev))
+		return dev_err_probe(dev, PTR_ERR(aw->bl_dev),
+				     "failed to register backlight\n");
+
+	return backlight_update_status(aw->bl_dev);
+}
+
+static void aw99703_shutdown(struct i2c_client *client)
+{
+	aw99703_power_off(i2c_get_clientdata(client));
+}
+
+static int aw99703_suspend(struct device *dev)
+{
+	struct aw99703_device *aw = dev_get_drvdata(dev);
+
+	if (aw->hwen_gpio) {
+		gpiod_set_value_cansleep(aw->hwen_gpio, 0);
+		aw->bl_enable = false;
+	}
+
+	return 0;
+}
+
+static int aw99703_resume(struct device *dev)
+{
+	struct aw99703_device *aw = dev_get_drvdata(dev);
+
+	return aw99703_hw_init(aw);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(aw99703_pm_ops, aw99703_suspend,
+				aw99703_resume);
+
+static const struct i2c_device_id aw99703_ids[] = {
+	{ "aw99703" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, aw99703_ids);
+
+static const struct of_device_id aw99703_match_table[] = {
+	{ .compatible = "awinic,aw99703" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, aw99703_match_table);
+
+static struct i2c_driver aw99703_i2c_driver = {
+	.probe = aw99703_probe,
+	.shutdown = aw99703_shutdown,
+	.id_table = aw99703_ids,
+	.driver = {
+		.name = "aw99703",
+		.of_match_table = aw99703_match_table,
+		.pm = pm_sleep_ptr(&aw99703_pm_ops),
+	},
+};
+module_i2c_driver(aw99703_i2c_driver);
+
+MODULE_AUTHOR("Luka Panio <lukapanio@gmail.com>");
+MODULE_DESCRIPTION("AWINIC AW99703 Backlight Driver");
+MODULE_LICENSE("GPL");
-- 
2.55.0