[RESEND PATCH v6 4/4] backlight: rt4831: Adds support for Richtek RT4831 backlight

cy_huang
2021-04-26T07:18:39Z

From: ChiYuan Huang <cy_huang@richtek.com>

Adds support for Richtek RT4831 backlight.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
Resend this v6 patch series to loop devicetree reviewers.

For next, if the typo in Kconfig 'common' to 'commonly' can be added the below line
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
drivers/video/backlight/Kconfig | 8 ++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/rt4831-backlight.c | 203 +++++++++++++++++++++++++++++
3 files changed, 212 insertions(+)
create mode 100644 drivers/video/backlight/rt4831-backlight.c

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index d83c87b..de96441 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -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
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 685f3f1..cae2c83 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -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
diff --git a/drivers/video/backlight/rt4831-backlight.c b/drivers/video/backlight/rt4831-backlight.c
new file mode 100644
index 00000000..42155c7
--- /dev/null
+++ b/drivers/video/backlight/rt4831-backlight.c
@@ -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");
--
2.7.4