Add Richtek RT8555 Backlight Support for samsung-gtelwifiue

arch/arm64/boot/dts/qcom/apq8016-samsung-gtelwifiue.dts

@@ -27,6 +27,29 @@
  };
  };
 
+ i2c-backlight {
+ status = "okay";
+ compatible = "i2c-gpio";
+ sda-gpios = <&msmgpio 24 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+ scl-gpios = <&msmgpio 25 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+
+ pinctrl-names = "default";
+ pinctrl-0 = <&bl_i2c_default>;
+
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ rt8555_backlight: backlight@31 {
+ compatible = "richtek,rt8555-backlight";
+ enable-gpios = <&msmgpio 69 GPIO_ACTIVE_HIGH>;
+ reg = <0x31>;
+
+ change-duty = <0>;
+ current-limit = <0xB6>;
+ driver-headroom = <1>;
+ };
+ };
+
  gpio-keys {
  compatible = "gpio-keys";
 
@@ -151,6 +174,7 @@
  compatible = "samsung,nt51017-b4p096wx5vp09";
  reg = <0>;
 
+ backlight = <&rt8555_backlight>;
  lcd-supply = <&reg_lcd>;
 
  port {
@@ -373,6 +397,22 @@
  bias-disable;
  };
 
+ bl_en_default: bl-en-default {
+ pins = "gpio69";
+ function = "gpio";
+
+ drive-strength = <2>;
+ bias-disable;
+ };
+
+ bl_i2c_default: bl-i2c-default {
+ pins = "gpio24", "gpio25";
+ function = "gpio";
+
+ drive-strength = <2>;
+ bias-disable;
+ };
+
  jack_default: jack-default {
  pins = "gpio110";
  function = "gpio";

drivers/video/backlight/Kconfig

@@ -297,6 +297,15 @@ config BACKLIGHT_RT4831
  It's commonly used to drive the display WLED. There're four channels
  inisde, and each channel can provide up to 30mA current.
 
+config BACKLIGHT_RT8555
+ tristate "Richtek RT8555 Backlight Driver"
+ depends on I2C
+ select REGMAP_I2C
+ help
+ This enables support for Richtek RT8555 Backlight driver.
+ It's commonly used to drive the display WLED. There are six channels
+ inisde, and each channel can provide up to 35mA current.
+
 config BACKLIGHT_SAHARA
  tristate "Tabletkiosk Sahara Touch-iT Backlight Driver"
  depends on X86

drivers/video/backlight/Makefile

@@ -50,6 +50,7 @@ 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-$(CONFIG_BACKLIGHT_RT8555) += rt8555-backlight.o
 obj-$(CONFIG_BACKLIGHT_SAHARA) += kb3886_bl.o
 obj-$(CONFIG_BACKLIGHT_SKY81452) += sky81452-backlight.o
 obj-$(CONFIG_BACKLIGHT_TOSA) += tosa_bl.o

drivers/video/backlight/rt8555-backlight.c

@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/err.h>
+#include <linux/backlight.h>
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define RT8555_MAX_BRIGHTNESS 1023
+
+/* Pulled from datashet */
+#define RT8555_DEFAULT_CURRENT_LIMIT 0x92
+#define RT8555_DEFAULT_LED_DRIVER_HEADROOM 0x00
+
+#define RT8555_REG_CFG0 0x00
+#define RT8555_REG_CFG1 0x01
+#define RT8555_REG_CFG8 0x08
+
+#define RT8555_REG_ILED_CURRENT_LIMIT 0x02
+#define RT8555_REG_ILED1_LSB 0x04
+#define RT8555_REG_ILED1_MSB 0x05
+
+#define RT8555_DIM_MODE_MASK BIT(0)
+#define RT8555_BRIGHTNESS_SOURCE_MASK BIT(1)
+#define RT8555_CHANGE_DUTY_MASK GENMASK(3, 2)
+#define RT8555_LED_DRIVER_HEADROOM_MASK GENMASK(3, 2)
+#define RT8555_MIX_26K_MASK BIT(7)
+#define RT8555_EN10BIT_MASK BIT(7)
+#define RT8555_LSB_MASK GENMASK(7, 0)
+
+struct rt8555_priv {
+ struct device *dev;
+ struct regmap *regmap;
+ struct backlight_device *bl;
+ struct gpio_desc *enable;
+
+ int change_duty;
+ int driver_headroom;
+ int current_limit;
+ bool pwm_dim_mode;
+};
+
+static int rt8555_bl_enable(struct rt8555_priv *priv)
+{
+ int ret;
+
+ if (!IS_ERR_OR_NULL(priv->enable)) {
+ gpiod_set_value(priv->enable, 1);
+
+ /* Wait for RT8555 to power on */
+ usleep_range(10000, 20000);
+ }
+
+ /* Set 10 bit mode */
+ ret = regmap_update_bits(priv->regmap, RT8555_REG_CFG1, RT8555_EN10BIT_MASK, 0xFF);
+ if (ret)
+ return ret;
+
+ /* Depend on i2c for brightness */
+ ret = regmap_update_bits(priv->regmap, RT8555_REG_CFG0,
+ RT8555_BRIGHTNESS_SOURCE_MASK, 0xFF);
+ if (ret)
+ return ret;
+
+ /* Whether we use PWM or mixed mode for dimming */
+ ret = regmap_update_bits(priv->regmap, RT8555_REG_CFG0, RT8555_DIM_MODE_MASK,
+ priv->pwm_dim_mode ? 0x00 : 0xFF);
+ if (ret)
+ return ret;
+
+ /* "Change Duty" for Mixed Mode */
+ ret = regmap_update_bits(priv->regmap, RT8555_REG_CFG0, RT8555_CHANGE_DUTY_MASK,
+ priv->change_duty << 2);
+ if (ret)
+ return ret;
+
+ /* Mixed mode frequency source, use fixed 26khz clock instead of PWM pin */
+ ret = regmap_update_bits(priv->regmap, RT8555_REG_CFG0, RT8555_MIX_26K_MASK, 0xFF);
+ if (ret)
+ return ret;
+
+ ret = regmap_update_bits(priv->regmap, RT8555_REG_CFG8, RT8555_LED_DRIVER_HEADROOM_MASK,
+ priv->driver_headroom << 2);
+ if (ret)
+ return ret;
+
+ ret = regmap_write(priv->regmap, RT8555_REG_ILED_CURRENT_LIMIT, priv->current_limit);
+ if (ret)
+ return ret;
+
+ return ret;
+}
+
+static int rt8555_bl_is_disabled(struct rt8555_priv *priv)
+{
+ if (!IS_ERR_OR_NULL(priv->enable))
+ return gpiod_get_value(priv->enable) == 0;
+ else
+ return 0;
+}
+
+static int rt8555_bl_update_status(struct backlight_device *bl_dev)
+{
+ struct rt8555_priv *priv = bl_get_data(bl_dev);
+ unsigned int brightness = backlight_get_brightness(bl_dev);
+ int ret;
+
+ /* Enable the IC (if disabled) before setting the brightness */
+ if (brightness && !IS_ERR_OR_NULL(priv->enable)) {
+ if (rt8555_bl_is_disabled(priv)) {
+ ret = rt8555_bl_enable(priv);
+ if (ret) {
+ dev_err(priv->dev, "rt8555_bl_enable failed with error %d", ret);
+ return ret;
+ }
+ }
+ }
+
+ ret = regmap_bulk_write(priv->regmap, RT8555_REG_ILED1_LSB, &brightness, 2);
+
+ /* Disable the IC after setting it to 0 */
+ if (brightness == 0)
+ if (!IS_ERR_OR_NULL(priv->enable))
+ gpiod_set_value(priv->enable, 0);
+
+ return 0;
+}
+
+static int rt8555_bl_get_brightness(struct backlight_device *bl_dev)
+{
+ struct rt8555_priv *priv = bl_get_data(bl_dev);
+ int ret;
+ int brightness;
+
+ /*
+ * If the RT8555 is disabled, there's no reason to turn it on just to read
+ * it back
+ */
+ if (rt8555_bl_is_disabled(priv))
+ return 0;
+
+ ret = regmap_bulk_read(priv->regmap, RT8555_REG_ILED1_LSB, &brightness, 2);
+ if (ret)
+ return ret;
+
+ return brightness;
+}
+
+static const struct backlight_ops rt8555_bl_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = rt8555_bl_update_status,
+ .get_brightness = rt8555_bl_get_brightness,
+};
+
+static const struct regmap_config rt8555_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+};
+
+static int rt8555_bl_probe(struct i2c_client *client)
+{
+ struct rt8555_priv *priv;
+ struct backlight_properties bl_props = {
+ .type = BACKLIGHT_RAW, .scale = BACKLIGHT_SCALE_LINEAR
+ };
+ int ret;
+ u32 brightness;
+
+ priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->dev = &client->dev;
+
+ priv->enable = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH);
+
+ priv->regmap = devm_regmap_init_i2c(client, &rt8555_regmap_config);
+ if (!priv->regmap) {
+ dev_err(&client->dev, "Failed to init regmap\n");
+ return -ENODEV;
+ }
+
+ ret = device_property_read_u32(&client->dev, "max-brightness", &brightness);
+ if (ret)
+ brightness = RT8555_MAX_BRIGHTNESS;
+
+ bl_props.max_brightness = min_t(u32, brightness, RT8555_MAX_BRIGHTNESS);
+
+ ret = device_property_read_u32(&client->dev, "default-brightness", &brightness);
+ if (ret)
+ brightness = bl_props.max_brightness;
+
+ bl_props.brightness = min_t(u32, brightness, bl_props.max_brightness);
+
+ priv->pwm_dim_mode = device_property_read_bool(&client->dev, "use-pwm-dimming-mode");
+
+ ret = device_property_read_u32(&client->dev, "change-duty", &priv->change_duty);
+ if (ret)
+ priv->change_duty = 3;
+
+ /* i2c register is only 2 bits, clamp value */
+ priv->change_duty = clamp(priv->change_duty, 0, 3);
+
+ ret = device_property_read_u32(&client->dev, "driver-headroom", &priv->driver_headroom);
+ if (ret)
+ priv->driver_headroom = RT8555_DEFAULT_LED_DRIVER_HEADROOM;
+
+ priv->driver_headroom = clamp(priv->driver_headroom, 0, 3);
+
+ ret = device_property_read_u32(&client->dev, "current-limit", &priv->current_limit);
+ if (ret)
+ priv->current_limit = RT8555_DEFAULT_CURRENT_LIMIT;
+
+ priv->bl = devm_backlight_device_register(&client->dev, client->name, &client->dev, priv,
+ &rt8555_bl_ops, &bl_props);
+ if (IS_ERR(priv->bl)) {
+ dev_err(&client->dev, "Failed to register backlight\n");
+ return PTR_ERR(priv->bl);
+ }
+
+ ret = rt8555_bl_enable(priv);
+ if (ret) {
+ dev_err(priv->dev, "rt8555_bl_enable failed with error %d",
+ ret);
+ return ret;
+ }
+
+ backlight_update_status(priv->bl);
+ i2c_set_clientdata(client, priv);
+
+ return 0;
+}
+
+static void rt8555_bl_remove(struct i2c_client *client)
+{
+ struct rt8555_priv *priv = i2c_get_clientdata(client);
+ struct backlight_device *bl_dev = priv->bl;
+
+ bl_dev->props.brightness = 0;
+ backlight_update_status(priv->bl);
+
+ if (!IS_ERR_OR_NULL(priv->enable))
+ gpiod_set_value(priv->enable, 0);
+}
+
+static const struct of_device_id __maybe_unused rt8555_bl_of_match[] = {
+ { .compatible = "richtek,rt8555-backlight", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, rt8555_bl_of_match);
+
+static struct i2c_driver rt8555_bl_driver = {
+ .driver = {
+ .name = "rt8555-backlight",
+ .of_match_table = rt8555_bl_of_match
+ },
+ .probe_new = rt8555_bl_probe,
+ .shutdown = rt8555_bl_remove
+};
+module_i2c_driver(rt8555_bl_driver);
+MODULE_AUTHOR("Michael Abood <[email protected]>");
+MODULE_LICENSE("GPL");