[PATCH v3 14/14] video: backlight: mt6370: Add Mediatek MT6370 support

From: ChiaEn Wu chiaen_wu@richtek.com

Add Mediatek MT6370 Backlight support.

Signed-off-by: ChiaEn Wu chiaen_wu@richtek.com ---

v3 - Refine bool properties parsing (pwm-enable, ovp-shutdown, ocp-shutdown) in DT parsing function - Refine u32 and u8 properties parsing (pwm-hys-input-th-steps, ovp-microvolt, ocp-microamp), from using register value to using actual value - Refine error string of "channle-use" parsing failed - Refine Kconfig help text --- drivers/video/backlight/Kconfig | 9 + drivers/video/backlight/Makefile | 1 + drivers/video/backlight/mt6370-backlight.c | 346 +++++++++++++++++++++++++++++ 3 files changed, 356 insertions(+) create mode 100644 drivers/video/backlight/mt6370-backlight.c

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index a003e02..7cd823d 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -268,6 +268,15 @@ config BACKLIGHT_MAX8925 If you have a LCD backlight connected to the WLED output of MAX8925 WLED output, say Y here to enable this driver.

+config BACKLIGHT_MT6370 + tristate "Mediatek MT6370 Backlight Driver" + depends on MFD_MT6370 + help + This enables support for Mediatek MT6370 Backlight driver. + It's commonly used to drive the display WLED. There are 4 channels + inside, and each channel supports up to 30mA of current capability + with 2048 current steps in exponential or linear mapping curves. + config BACKLIGHT_APPLE tristate "Apple Backlight Driver" depends on X86 && ACPI diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile index cae2c83..e815f3f 100644 --- a/drivers/video/backlight/Makefile +++ b/drivers/video/backlight/Makefile @@ -44,6 +44,7 @@ obj-$(CONFIG_BACKLIGHT_LP855X) += lp855x_bl.o obj-$(CONFIG_BACKLIGHT_LP8788) += lp8788_bl.o obj-$(CONFIG_BACKLIGHT_LV5207LP) += lv5207lp.o obj-$(CONFIG_BACKLIGHT_MAX8925) += max8925_bl.o +obj-$(CONFIG_BACKLIGHT_MT6370) += mt6370-backlight.o obj-$(CONFIG_BACKLIGHT_OMAP1) += omap1_bl.o obj-$(CONFIG_BACKLIGHT_PANDORA) += pandora_bl.o obj-$(CONFIG_BACKLIGHT_PCF50633) += pcf50633-backlight.o diff --git a/drivers/video/backlight/mt6370-backlight.c b/drivers/video/backlight/mt6370-backlight.c new file mode 100644 index 0000000..c2ba09d --- /dev/null +++ b/drivers/video/backlight/mt6370-backlight.c @@ -0,0 +1,346 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/backlight.h> +#include <linux/bitfield.h> +#include <linux/bits.h> +#include <linux/gpio/consumer.h> +#include <linux/gpio/driver.h> +#include <linux/kernel.h> +#include <linux/log2.h> +#include <linux/minmax.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> + +#define MT6370_REG_DEV_INFO 0x100 +#define MT6370_REG_BL_EN 0x1A0 +#define MT6370_REG_BL_BSTCTRL 0x1A1 +#define MT6370_REG_BL_PWM 0x1A2 +#define MT6370_REG_BL_DIM2 0x1A4 + +#define MT6370_VENID_MASK GENMASK(7, 4) +#define MT6370_BL_EXT_EN_MASK BIT(7) +#define MT6370_BL_EN_MASK BIT(6) +#define MT6370_BL_CONFIG_MASK BIT(0) +#define MT6370_BL_CH_MASK GENMASK(5, 2) +#define MT6370_BL_DIM2_MASK GENMASK(2, 0) +#define MT6370_BL_DUMMY_6372_MASK GENMASK(2, 0) +#define MT6370_BL_DIM2_6372_SHIFT 3 +#define MT6370_BL_PWM_EN_MASK BIT(7) +#define MT6370_BL_PWM_HYS_EN_MASK BIT(2) +#define MT6370_BL_PWM_HYS_SEL_MASK GENMASK(1, 0) +#define MT6370_BL_OVP_EN_MASK BIT(7) +#define MT6370_BL_OVP_SEL_MASK GENMASK(6, 5) +#define MT6370_BL_OC_EN_MASK BIT(3) +#define MT6370_BL_OC_SEL_MASK GENMASK(2, 1) + +#define MT6370_BL_PWM_HYS_TH_MIN_STEP 1 +#define MT6370_BL_PWM_HYS_TH_MAX_STEP 64 +#define MT6370_BL_OVP_MIN_UV 17000000 +#define MT6370_BL_OVP_MAX_UV 29000000 +#define MT6370_BL_OVP_STEP_UV 4000000 +#define MT6370_BL_OCP_MIN_UA 900000 +#define MT6370_BL_OCP_MAX_UA 1800000 +#define MT6370_BL_OCP_STEP_UA 300000 +#define MT6370_BL_MAX_BRIGHTNESS 2048 +#define MT6370_BL_MAX_CH 15 + +enum { + MT6370_VID_COMMON = 0, + MT6370_VID_6372, +}; + +struct mt6370_priv { + int vid_type; + struct backlight_device *bl; + struct device *dev; + struct gpio_desc *enable_gpio; + struct regmap *regmap; +}; + +static int mt6370_bl_update_status(struct backlight_device *bl_dev) +{ + struct mt6370_priv *priv = bl_get_data(bl_dev); + int brightness = backlight_get_brightness(bl_dev); + unsigned int enable_val; + u8 brightness_val[2]; + int ret; + + if (brightness) { + brightness_val[0] = (brightness - 1) & MT6370_BL_DIM2_MASK; + brightness_val[1] = (brightness - 1) + >> fls(MT6370_BL_DIM2_MASK); + + /* + * To make MT6372 using 14 bits to control the brightness + * backward compatible with 11 bits brightness control + * (like MT6370 and MT6371 do), we left shift the value + * and pad with 1 to remaining bits. Hence, the MT6372's + * backlight brightness will be almost the same as MT6370's + * and MT6371's. + */ + if (priv->vid_type == MT6370_VID_6372) { + brightness_val[0] <<= MT6370_BL_DIM2_6372_SHIFT; + brightness_val[0] |= MT6370_BL_DUMMY_6372_MASK; + } + + ret = regmap_raw_write(priv->regmap, MT6370_REG_BL_DIM2, + brightness_val, sizeof(brightness_val)); + if (ret) + return ret; + } + + if (priv->enable_gpio) + gpiod_set_value(priv->enable_gpio, brightness ? 1 : 0); + + enable_val = brightness ? MT6370_BL_EN_MASK : 0; + return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN, + MT6370_BL_EN_MASK, enable_val); +} + +static int mt6370_bl_get_brightness(struct backlight_device *bl_dev) +{ + struct mt6370_priv *priv = bl_get_data(bl_dev); + unsigned int enable; + u8 brightness_val[2]; + int brightness, ret; + + ret = regmap_read(priv->regmap, MT6370_REG_BL_EN, &enable); + if (ret) + return ret; + + if (!(enable & MT6370_BL_EN_MASK)) + return 0; + + ret = regmap_raw_read(priv->regmap, MT6370_REG_BL_DIM2, + brightness_val, sizeof(brightness_val)); + if (ret) + return ret; + + if (priv->vid_type == MT6370_VID_6372) + brightness_val[0] >>= MT6370_BL_DIM2_6372_SHIFT; + + brightness = brightness_val[1] << fls(MT6370_BL_DIM2_MASK); + brightness += (brightness_val[0] & MT6370_BL_DIM2_MASK); + + return brightness + 1; +} + +static const struct backlight_ops mt6370_bl_ops = { + .options = BL_CORE_SUSPENDRESUME, + .update_status = mt6370_bl_update_status, + .get_brightness = mt6370_bl_get_brightness, +}; + +static int mt6370_init_backlight_properties(struct mt6370_priv *priv, + struct backlight_properties *props) +{ + struct device *dev = priv->dev; + u8 prop_val; + u32 brightness, ovp_uV, ocp_uA; + unsigned int mask, val; + int ret; + + /* Vendor optional properties */ + val = 0; + if (device_property_read_bool(dev, "mediatek,bled-pwm-enable")) + val |= MT6370_BL_PWM_EN_MASK; + + if (device_property_read_bool(dev, "mediatek,bled-pwm-hys-enable")) + val |= MT6370_BL_PWM_HYS_EN_MASK; + + ret = device_property_read_u8(dev, + "mediatek,bled-pwm-hys-input-th-steps", + &prop_val); + if (!ret) { + prop_val = clamp_val(prop_val, + MT6370_BL_PWM_HYS_TH_MIN_STEP, + MT6370_BL_PWM_HYS_TH_MAX_STEP); + /* + * prop_val = 1 --> 1 steps --> 0x00 + * prop_val = 2 ~ 4 --> 4 steps --> 0x01 + * prop_val = 5 ~ 16 --> 16 steps --> 0x10 + * prop_val = 17 ~ 64 --> 64 steps --> 0x11 + */ + prop_val = (ilog2(roundup_pow_of_two(prop_val)) + 1) >> 1; + val |= prop_val << (ffs(MT6370_BL_PWM_HYS_SEL_MASK) - 1); + } + + ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM, + val, val); + if (ret) + return ret; + + val = 0; + if (device_property_read_bool(dev, "mediatek,bled-ovp-shutdown")) + val |= MT6370_BL_OVP_EN_MASK; + + ret = device_property_read_u32(dev, "mediatek,bled-ovp-microvolt", + &ovp_uV); + if (!ret) { + ovp_uV = clamp_val(ovp_uV, MT6370_BL_OVP_MIN_UV, + MT6370_BL_OVP_MAX_UV); + ovp_uV = DIV_ROUND_UP(ovp_uV - MT6370_BL_OVP_MIN_UV, + MT6370_BL_OVP_STEP_UV); + val |= ovp_uV << (ffs(MT6370_BL_OVP_SEL_MASK) - 1); + } + + if (device_property_read_bool(dev, "mediatek,bled-ocp-shutdown")) + val |= MT6370_BL_OC_EN_MASK; + + ret = device_property_read_u32(dev, "mediatek,bled-ocp-microamp", + &ocp_uA); + if (!ret) { + ocp_uA = clamp_val(ocp_uA, MT6370_BL_OCP_MIN_UA, + MT6370_BL_OCP_MAX_UA); + ocp_uA = DIV_ROUND_UP(ocp_uA - MT6370_BL_OCP_MIN_UA, + MT6370_BL_OCP_STEP_UA); + val |= ocp_uA << (ffs(MT6370_BL_OC_SEL_MASK) - 1); + } + + ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL, + val, val); + if (ret) + return ret; + + /* Common properties */ + ret = device_property_read_u32(dev, "max-brightness", &brightness); + if (ret) + brightness = MT6370_BL_MAX_BRIGHTNESS; + + props->max_brightness = min_t(u32, brightness, + MT6370_BL_MAX_BRIGHTNESS); + + ret = device_property_read_u32(dev, "default-brightness", &brightness); + if (ret) + brightness = props->max_brightness; + + props->brightness = min_t(u32, brightness, props->max_brightness); + + val = 0; + prop_val = 0; + ret = device_property_read_u8(dev, "mediatek,bled-channel-use", + &prop_val); + if (ret) { + dev_err(dev, "mediatek,bled-channel-use DT property missing\n"); + return ret; + } + + if (!prop_val || prop_val > MT6370_BL_MAX_CH) { + dev_err(dev, + "No channel specified or over than upper bound (%d)\n", + prop_val); + return -EINVAL; + } + + mask = MT6370_BL_EXT_EN_MASK | MT6370_BL_CH_MASK; + val = prop_val << (ffs(MT6370_BL_CH_MASK) - 1); + + if (priv->enable_gpio) + val |= MT6370_BL_EXT_EN_MASK; + + return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN, mask, val); +} + +static int mt6370_check_vendor_info(struct mt6370_priv *priv) +{ + /* + * MT6372 uses 14 bits to control the brightness but MT6370 and MT6371 + * use 11 bits. They are different so we have to use this function to + * check the vendor ID and use different methods to calculate the + * brightness. + */ + unsigned int dev_info, vid; + int ret; + + ret = regmap_read(priv->regmap, MT6370_REG_DEV_INFO, &dev_info); + if (ret) + return ret; + + vid = FIELD_GET(MT6370_VENID_MASK, dev_info); + if (vid == 0x9 || vid == 0xb) + priv->vid_type = MT6370_VID_6372; + else + priv->vid_type = MT6370_VID_COMMON; + + return 0; +} + +static int mt6370_bl_probe(struct platform_device *pdev) +{ + struct mt6370_priv *priv; + struct backlight_properties 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_probe(&pdev->dev, -ENODEV, "Failed to get regmap\n"); + + ret = mt6370_check_vendor_info(priv); + if (ret) + dev_err_probe(&pdev->dev, ret, "Failed to check vendor info\n"); + + priv->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable", + GPIOD_OUT_HIGH); + if (IS_ERR(priv->enable_gpio)) + dev_err_probe(&pdev->dev, PTR_ERR(priv->enable_gpio), + "Failed to get 'enable' gpio\n"); + + ret = mt6370_init_backlight_properties(priv, &props); + if (ret) + dev_err_probe(&pdev->dev, ret, + "Failed to init backlight properties\n"); + + priv->bl = devm_backlight_device_register(&pdev->dev, pdev->name, + &pdev->dev, priv, + &mt6370_bl_ops, &props); + if (IS_ERR(priv->bl)) + dev_err_probe(&pdev->dev, PTR_ERR(priv->bl), + "Failed to register backlight\n"); + + backlight_update_status(priv->bl); + platform_set_drvdata(pdev, priv); + + return 0; +} + +static int mt6370_bl_remove(struct platform_device *pdev) +{ + struct mt6370_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 mt6370_bl_of_match[] = { + { .compatible = "mediatek,mt6370-backlight", }, + {} +}; +MODULE_DEVICE_TABLE(of, mt6370_bl_of_match); + +static struct platform_driver mt6370_bl_driver = { + .driver = { + .name = "mt6370-backlight", + .of_match_table = mt6370_bl_of_match, + }, + .probe = mt6370_bl_probe, + .remove = mt6370_bl_remove, +}; +module_platform_driver(mt6370_bl_driver); + +MODULE_AUTHOR("ChiaEn Wu chiaen_wu@richtek.com"); +MODULE_DESCRIPTION("Mediatek MT6370 Backlight Driver"); +MODULE_LICENSE("GPL v2");