[PATCH v6 1/4] mfd: rt4831: Adds support for Richtek RT4831

@@ -1065,6 +1065,16 @@ config MFD_RDC321X
 	  southbridge which provides access to GPIOs and Watchdog using the
 	  southbridge PCI device configuration space.
 
+config MFD_RT4831
+	tristate "Richtek RT4831 four channel WLED and Display Bias Voltage"
+	depends on I2C
+	select MFD_CORE
+	select REGMAP_I2C
+	help
+	  This enables support for the Richtek RT4831 that includes 4 channel
+	  WLED driving and Display Bias Voltage. It's commonly used to provide
+	  power to the LCD display and LCD backlight.
+
 config MFD_RT5033
 	tristate "Richtek RT5033 Power Management IC"
 	depends on I2C

@@ -235,6 +235,7 @@ obj-$(CONFIG_MFD_MENF21BMC)	+= menf21bmc.o
 obj-$(CONFIG_MFD_HI6421_PMIC)	+= hi6421-pmic-core.o
 obj-$(CONFIG_MFD_HI655X_PMIC)   += hi655x-pmic.o
 obj-$(CONFIG_MFD_DLN2)		+= dln2.o
+obj-$(CONFIG_MFD_RT4831)	+= rt4831.o
 obj-$(CONFIG_MFD_RT5033)	+= rt5033.o
 obj-$(CONFIG_MFD_SKY81452)	+= sky81452.o
 

@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2021 Richtek Technology Corp.
+ *
+ * Author: ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#define RT4831_REG_REVISION	0x01
+#define RT4831_REG_ENABLE	0x08
+#define RT4831_REG_I2CPROT	0x15
+
+#define RICHTEK_VENDOR_ID	0x03
+#define RT4831_VID_MASK		GENMASK(1, 0)
+#define RT4831_RESET_MASK	BIT(7)
+#define RT4831_I2CSAFETMR_MASK	BIT(0)
+
+static const struct mfd_cell rt4831_subdevs[] = {
+	MFD_CELL_OF("rt4831-backlight", NULL, NULL, 0, 0, "richtek,rt4831-backlight"),
+	MFD_CELL_NAME("rt4831-regulator")
+};
+
+static bool rt4831_is_accessible_reg(struct device *dev, unsigned int reg)
+{
+	if (reg >= RT4831_REG_REVISION && reg <= RT4831_REG_I2CPROT)
+		return true;
+	return false;
+}
+
+static const struct regmap_config rt4831_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = RT4831_REG_I2CPROT,
+
+	.readable_reg = rt4831_is_accessible_reg,
+	.writeable_reg = rt4831_is_accessible_reg,
+};
+
+static int rt4831_probe(struct i2c_client *client)
+{
+	struct gpio_desc *enable_gpio;
+	struct regmap *regmap;
+	unsigned int chip_id;
+	int ret;
+
+	enable_gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH);
+	if (IS_ERR(enable_gpio)) {
+		dev_err(&client->dev, "Failed to get 'enable' GPIO\n");
+		return PTR_ERR(enable_gpio);
+	}
+
+	regmap = devm_regmap_init_i2c(client, &rt4831_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "Failed to initialize regmap\n");
+		return PTR_ERR(regmap);
+	}
+
+	ret = regmap_read(regmap, RT4831_REG_REVISION, &chip_id);
+	if (ret) {
+		dev_err(&client->dev, "Failed to get H/W revision\n");
+		return ret;
+	}
+
+	if ((chip_id & RT4831_VID_MASK) != RICHTEK_VENDOR_ID) {
+		dev_err(&client->dev, "Chip vendor ID 0x%02x not matched\n", chip_id);
+		return -ENODEV;
+	}
+
+	/*
+	 * Used to prevent the abnormal shutdown.
+	 * If SCL/SDA both keep low for one second to reset HW.
+	 */
+	ret = regmap_update_bits(regmap, RT4831_REG_I2CPROT, RT4831_I2CSAFETMR_MASK,
+				 RT4831_I2CSAFETMR_MASK);
+	if (ret) {
+		dev_err(&client->dev, "Failed to enable I2C safety timer\n");
+		return ret;
+	}
+
+	return devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO, rt4831_subdevs,
+				    ARRAY_SIZE(rt4831_subdevs), NULL, 0, NULL);
+}
+
+static int rt4831_remove(struct i2c_client *client)
+{
+	struct regmap *regmap = dev_get_regmap(&client->dev, NULL);
+
+	/* Disable WLED and DSV outputs */
+	return regmap_update_bits(regmap, RT4831_REG_ENABLE, RT4831_RESET_MASK, RT4831_RESET_MASK);
+}
+
+static const struct of_device_id __maybe_unused rt4831_of_match[] = {
+	{ .compatible = "richtek,rt4831", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rt4831_of_match);
+
+static struct i2c_driver rt4831_driver = {
+	.driver = {
+		.name = "rt4831",
+		.of_match_table = rt4831_of_match,
+	},
+	.probe_new = rt4831_probe,
+	.remove = rt4831_remove,
+};
+module_i2c_driver(rt4831_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_LICENSE("GPL v2");

@@ -0,0 +1,90 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mfd/richtek,rt4831.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Richtek RT4831 DSV and Backlight Integrated IC
+
+maintainers:
+  - ChiYuan Huang <cy_huang@richtek.com>
+
+description: |
+  RT4831 is a multifunctional device that can provide power to the LCD display
+  and LCD backlight.
+
+  For Display Bias Voltage DSVP and DSVN, the output range is about 4V to 6.5V.
+  It's sufficient to meet the current LCD power requirement.
+
+  For the LCD backlight, it can provide four channel WLED driving capability.
+  Each channel driving current is up to 30mA
+
+  Datasheet is available at
+  https://www.richtek.com/assets/product_file/RT4831A/DS4831A-05.pdf
+
+properties:
+  compatible:
+    const: richtek,rt4831
+
+  reg:
+    description: I2C device address.
+    maxItems: 1
+
+  enable-gpios:
+    description: |
+      GPIO to enable/disable the chip. It is optional.
+      Some usage directly tied this pin to follow VIO 1.8V power on sequence.
+    maxItems: 1
+
+  regulators:
+    $ref: ../regulator/richtek,rt4831-regulator.yaml
+
+  backlight:
+    $ref: ../leds/backlight/richtek,rt4831-backlight.yaml
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/leds/rt4831-backlight.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      rt4831@11 {
+        compatible = "richtek,rt4831";
+        reg = <0x11>;
+
+        regulators {
+          DSVLCM {
+            regulator-min-microvolt = <4000000>;
+            regulator-max-microvolt = <7150000>;
+            regulator-allow-bypass;
+          };
+          DSVP {
+            regulator-name = "rt4831-dsvp";
+            regulator-min-microvolt = <4000000>;
+            regulator-max-microvolt = <6500000>;
+            regulator-boot-on;
+          };
+          DSVN {
+            regulator-name = "rt4831-dsvn";
+            regulator-min-microvolt = <4000000>;
+            regulator-max-microvolt = <6500000>;
+            regulator-boot-on;
+          };
+        };
+
+        backlight {
+          compatible = "richtek,rt4831-backlight";
+          default-brightness = <1024>;
+          max-brightness = <2048>;
+          richtek,bled-ovp-sel = /bits/ 8 <RT4831_BLOVPLVL_21V>;
+          richtek,channel-use = /bits/ 8 <RT4831_BLED_ALLCHEN>;
+        };
+      };
+    };

@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/richtek,rt4831-backlight.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Richtek RT4831 Backlight
+
+maintainers:
+  - ChiYuan Huang <cy_huang@richtek.com>
+
+description: |
+  RT4831 is a mutifunctional device that can provide power to the LCD display
+  and LCD backlight.
+
+  For the LCD backlight, it can provide four channel WLED driving capability.
+  Each channel driving current is up to 30mA
+
+  Datasheet is available at
+  https://www.richtek.com/assets/product_file/RT4831A/DS4831A-05.pdf
+
+properties:
+  compatible:
+    const: richtek,rt4831-backlight
+
+  default-brightness:
+    description: |
+      The default brightness that applied to the system on start-up.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 2048
+
+  max-brightness:
+    description: |
+      The max brightness for the H/W limit
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 2048
+
+  richtek,pwm-enable:
+    description: |
+      Specify the backlight dimming following by PWM duty or by SW control.
+    type: boolean
+
+  richtek,bled-ovp-sel:
+    description: |
+      Backlight OVP level selection, currently support 17V/21V/25V/29V.
+    $ref: /schemas/types.yaml#/definitions/uint8
+    default: 1
+    minimum: 0
+    maximum: 3
+
+  richtek,channel-use:
+    description: |
+      Backlight LED channel to be used.
+      BIT 0/1/2/3 is used to indicate led channel 1/2/3/4 enable or disable.
+    $ref: /schemas/types.yaml#/definitions/uint8
+    minimum: 1
+    maximum: 15
+
+required:
+  - compatible
+  - richtek,channel-use
+
+additionalProperties: false

@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
+/*
+ * This header provides constants for rt4831 backlight bindings.
+ *
+ * Copyright (C) 2020, Richtek Technology Corp.
+ * Author: ChiYuan Huang <cy_huang@richtek.com>
+ */
+
+#ifndef _DT_BINDINGS_RT4831_BACKLIGHT_H
+#define _DT_BINDINGS_RT4831_BACKLIGHT_H
+
+#define RT4831_BLOVPLVL_17V	0
+#define RT4831_BLOVPLVL_21V	1
+#define RT4831_BLOVPLVL_25V	2
+#define RT4831_BLOVPLVL_29V	3
+
+#define RT4831_BLED_CH1EN	(1 << 0)
+#define RT4831_BLED_CH2EN	(1 << 1)
+#define RT4831_BLED_CH3EN	(1 << 2)
+#define RT4831_BLED_CH4EN	(1 << 3)
+#define RT4831_BLED_ALLCHEN	((1 << 4) - 1)
+
+#endif /* _DT_BINDINGS_RT4831_BACKLIGHT_H */

@@ -289,6 +289,14 @@ config BACKLIGHT_QCOM_WLED
 	  If you have the Qualcomm PMIC, say Y to enable a driver for the
 	  WLED block. Currently it supports PM8941 and PMI8998.
 
+config BACKLIGHT_RT4831
+	tristate "Richtek RT4831 Backlight Driver"
+	depends on MFD_RT4831
+	help
+	  This enables support for Richtek RT4831 Backlight driver.
+	  It's common used to drive the display WLED. There're four channels
+	  inisde, and each channel can provide up to 30mA current.
+
 config BACKLIGHT_SAHARA
 	tristate "Tabletkiosk Sahara Touch-iT Backlight Driver"
 	depends on X86

@@ -49,6 +49,7 @@ obj-$(CONFIG_BACKLIGHT_PANDORA)		+= pandora_bl.o
 obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o
 obj-$(CONFIG_BACKLIGHT_PWM)		+= pwm_bl.o
 obj-$(CONFIG_BACKLIGHT_QCOM_WLED)	+= qcom-wled.o
+obj-$(CONFIG_BACKLIGHT_RT4831)		+= rt4831-backlight.o
 obj-$(CONFIG_BACKLIGHT_SAHARA)		+= kb3886_bl.o
 obj-$(CONFIG_BACKLIGHT_SKY81452)	+= sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o

@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <dt-bindings/leds/rt4831-backlight.h>
+#include <linux/backlight.h>
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#define RT4831_REG_BLCFG	0x02
+#define RT4831_REG_BLDIML	0x04
+#define RT4831_REG_ENABLE	0x08
+
+#define RT4831_BLMAX_BRIGHTNESS	2048
+
+#define RT4831_BLOVP_MASK	GENMASK(7, 5)
+#define RT4831_BLOVP_SHIFT	5
+#define RT4831_BLPWMEN_MASK	BIT(0)
+#define RT4831_BLEN_MASK	BIT(4)
+#define RT4831_BLCH_MASK	GENMASK(3, 0)
+#define RT4831_BLDIML_MASK	GENMASK(2, 0)
+#define RT4831_BLDIMH_MASK	GENMASK(10, 3)
+#define RT4831_BLDIMH_SHIFT	3
+
+struct rt4831_priv {
+	struct device *dev;
+	struct regmap *regmap;
+	struct backlight_device *bl;
+};
+
+static int rt4831_bl_update_status(struct backlight_device *bl_dev)
+{
+	struct rt4831_priv *priv = bl_get_data(bl_dev);
+	int brightness = backlight_get_brightness(bl_dev);
+	unsigned int enable = brightness ? RT4831_BLEN_MASK : 0;
+	u8 v[2];
+	int ret;
+
+	if (brightness) {
+		v[0] = (brightness - 1) & RT4831_BLDIML_MASK;
+		v[1] = ((brightness - 1) & RT4831_BLDIMH_MASK) >> RT4831_BLDIMH_SHIFT;
+
+		ret = regmap_raw_write(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
+		if (ret)
+			return ret;
+	}
+
+	return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLEN_MASK, enable);
+
+}
+
+static int rt4831_bl_get_brightness(struct backlight_device *bl_dev)
+{
+	struct rt4831_priv *priv = bl_get_data(bl_dev);
+	unsigned int val;
+	u8 v[2];
+	int ret;
+
+	ret = regmap_read(priv->regmap, RT4831_REG_ENABLE, &val);
+	if (ret)
+		return ret;
+
+	if (!(val & RT4831_BLEN_MASK))
+		return 0;
+
+	ret = regmap_raw_read(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
+	if (ret)
+		return ret;
+
+	ret = (v[1] << RT4831_BLDIMH_SHIFT) + (v[0] & RT4831_BLDIML_MASK) + 1;
+
+	return ret;
+}
+
+static const struct backlight_ops rt4831_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = rt4831_bl_update_status,
+	.get_brightness = rt4831_bl_get_brightness,
+};
+
+static int rt4831_parse_backlight_properties(struct rt4831_priv *priv,
+					     struct backlight_properties *bl_props)
+{
+	struct device *dev = priv->dev;
+	u8 propval;
+	u32 brightness;
+	unsigned int val = 0;
+	int ret;
+
+	/* common properties */
+	ret = device_property_read_u32(dev, "max-brightness", &brightness);
+	if (ret)
+		brightness = RT4831_BLMAX_BRIGHTNESS;
+
+	bl_props->max_brightness = min_t(u32, brightness, RT4831_BLMAX_BRIGHTNESS);
+
+	ret = device_property_read_u32(dev, "default-brightness", &brightness);
+	if (ret)
+		brightness = bl_props->max_brightness;
+
+	bl_props->brightness = min_t(u32, brightness, bl_props->max_brightness);
+
+	/* vendor properties */
+	if (device_property_read_bool(dev, "richtek,pwm-enable"))
+		val = RT4831_BLPWMEN_MASK;
+
+	ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLPWMEN_MASK, val);
+	if (ret)
+		return ret;
+
+	ret = device_property_read_u8(dev, "richtek,bled-ovp-sel", &propval);
+	if (ret)
+		propval = RT4831_BLOVPLVL_21V;
+
+	propval = min_t(u8, propval, RT4831_BLOVPLVL_29V);
+	ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLOVP_MASK,
+				 propval << RT4831_BLOVP_SHIFT);
+	if (ret)
+		return ret;
+
+	ret = device_property_read_u8(dev, "richtek,channel-use", &propval);
+	if (ret) {
+		dev_err(dev, "richtek,channel-use DT property missing\n");
+		return ret;
+	}
+
+	if (!(propval & RT4831_BLCH_MASK)) {
+		dev_err(dev, "No channel specified\n");
+		return -EINVAL;
+	}
+
+	return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLCH_MASK, propval);
+}
+
+static int rt4831_bl_probe(struct platform_device *pdev)
+{
+	struct rt4831_priv *priv;
+	struct backlight_properties bl_props = { .type = BACKLIGHT_RAW,
+						 .scale = BACKLIGHT_SCALE_LINEAR };
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = &pdev->dev;
+
+	priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!priv->regmap) {
+		dev_err(&pdev->dev, "Failed to init regmap\n");
+		return -ENODEV;
+	}
+
+	ret = rt4831_parse_backlight_properties(priv, &bl_props);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to parse backlight properties\n");
+		return ret;
+	}
+
+	priv->bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, priv,
+						  &rt4831_bl_ops, &bl_props);
+	if (IS_ERR(priv->bl)) {
+		dev_err(&pdev->dev, "Failed to register backlight\n");
+		return PTR_ERR(priv->bl);
+	}
+
+	backlight_update_status(priv->bl);
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static int rt4831_bl_remove(struct platform_device *pdev)
+{
+	struct rt4831_priv *priv = platform_get_drvdata(pdev);
+	struct backlight_device *bl_dev = priv->bl;
+
+	bl_dev->props.brightness = 0;
+	backlight_update_status(priv->bl);
+
+	return 0;
+}
+
+static const struct of_device_id __maybe_unused rt4831_bl_of_match[] = {
+	{ .compatible = "richtek,rt4831-backlight", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rt4831_bl_of_match);
+
+static struct platform_driver rt4831_bl_driver = {
+	.driver = {
+		.name = "rt4831-backlight",
+		.of_match_table = rt4831_bl_of_match,
+	},
+	.probe = rt4831_bl_probe,
+	.remove = rt4831_bl_remove,
+};
+module_platform_driver(rt4831_bl_driver);
+
+MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
+MODULE_LICENSE("GPL v2");