From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- drivers/video/backlight/mt6370-backlight.c | 348 +++++++++++++++++++++++++++++ 1 file changed, 348 insertions(+) create mode 100644 drivers/video/backlight/mt6370-backlight.c (limited to 'drivers/video/backlight/mt6370-backlight.c') diff --git a/drivers/video/backlight/mt6370-backlight.c b/drivers/video/backlight/mt6370-backlight.c new file mode 100644 index 000000000..7905372c2 --- /dev/null +++ b/drivers/video/backlight/mt6370-backlight.c @@ -0,0 +1,348 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2022 Richtek Technology Corp. + * + * Author: ChiaEn Wu + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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_CODE_MASK BIT(0) +#define MT6370_BL_CH_MASK GENMASK(5, 2) +#define MT6370_BL_CH_SHIFT 2 +#define MT6370_BL_DIM2_COMMON_MASK GENMASK(2, 0) +#define MT6370_BL_DIM2_COMMON_SHIFT 3 +#define MT6370_BL_DIM2_6372_MASK GENMASK(5, 0) +#define MT6370_BL_DIM2_6372_SHIFT 6 +#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_OVP_SEL_SHIFT 5 +#define MT6370_BL_OC_EN_MASK BIT(3) +#define MT6370_BL_OC_SEL_MASK GENMASK(2, 1) +#define MT6370_BL_OC_SEL_SHIFT 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_COMMON_BRIGHTNESS 2048 +#define MT6370_BL_MAX_6372_BRIGHTNESS 16384 +#define MT6370_BL_MAX_CH 15 + +enum { + MT6370_VID_COMMON = 1, + MT6370_VID_6372, +}; + +struct mt6370_priv { + u8 dim2_mask; + u8 dim2_shift; + int def_max_brightness; + 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) & priv->dim2_mask; + brightness_val[1] = (brightness - 1) >> priv->dim2_shift; + + ret = regmap_raw_write(priv->regmap, MT6370_REG_BL_DIM2, + brightness_val, sizeof(brightness_val)); + if (ret) + return ret; + } + + gpiod_set_value(priv->enable_gpio, !!brightness); + + 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; + + brightness = brightness_val[1] << priv->dim2_shift; + brightness += brightness_val[0] & priv->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 = prop_val <= 1 ? 0 : + prop_val <= 4 ? 1 : + prop_val <= 16 ? 2 : 3; + val |= prop_val; + } + + 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 << MT6370_BL_OVP_SEL_SHIFT; + } + + 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 << MT6370_BL_OC_SEL_SHIFT; + } + + 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 = priv->def_max_brightness; + + props->max_brightness = min_t(u32, brightness, priv->def_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; + if (device_property_read_bool(dev, "mediatek,bled-exponential-mode-enable")) { + val |= MT6370_BL_CODE_MASK; + props->scale = BACKLIGHT_SCALE_NON_LINEAR; + } else + props->scale = BACKLIGHT_SCALE_LINEAR; + + 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 << MT6370_BL_CH_SHIFT; + + 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) +{ + /* + * Because MT6372 uses 14 bits to control the brightness, + * MT6370 and MT6371 use 11 bits. This function is used + * to check the vendor's ID and set the relative hardware + * mask, shift and default maximum brightness value that + * should be used. + */ + unsigned int dev_info, hw_vid, of_vid; + int ret; + + ret = regmap_read(priv->regmap, MT6370_REG_DEV_INFO, &dev_info); + if (ret) + return ret; + + of_vid = (uintptr_t)device_get_match_data(priv->dev); + hw_vid = FIELD_GET(MT6370_VENID_MASK, dev_info); + hw_vid = (hw_vid == 0x9 || hw_vid == 0xb) ? MT6370_VID_6372 : MT6370_VID_COMMON; + if (hw_vid != of_vid) + return dev_err_probe(priv->dev, -EINVAL, + "Buggy DT, wrong compatible string\n"); + + if (hw_vid == MT6370_VID_6372) { + priv->dim2_mask = MT6370_BL_DIM2_6372_MASK; + priv->dim2_shift = MT6370_BL_DIM2_6372_SHIFT; + priv->def_max_brightness = MT6370_BL_MAX_6372_BRIGHTNESS; + } else { + priv->dim2_mask = MT6370_BL_DIM2_COMMON_MASK; + priv->dim2_shift = MT6370_BL_DIM2_COMMON_SHIFT; + priv->def_max_brightness = MT6370_BL_MAX_COMMON_BRIGHTNESS; + } + + return 0; +} + +static int mt6370_bl_probe(struct platform_device *pdev) +{ + struct backlight_properties props = { + .type = BACKLIGHT_RAW, + }; + struct device *dev = &pdev->dev; + struct mt6370_priv *priv; + int ret; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->dev = dev; + + priv->regmap = dev_get_regmap(dev->parent, NULL); + if (!priv->regmap) + return dev_err_probe(dev, -ENODEV, "Failed to get regmap\n"); + + ret = mt6370_check_vendor_info(priv); + if (ret) + return dev_err_probe(dev, ret, "Failed to check vendor info\n"); + + priv->enable_gpio = devm_gpiod_get_optional(dev, "enable", + GPIOD_OUT_HIGH); + if (IS_ERR(priv->enable_gpio)) + return dev_err_probe(dev, PTR_ERR(priv->enable_gpio), + "Failed to get 'enable' gpio\n"); + + ret = mt6370_init_backlight_properties(priv, &props); + if (ret) + return dev_err_probe(dev, ret, + "Failed to init backlight properties\n"); + + priv->bl = devm_backlight_device_register(dev, pdev->name, dev, priv, + &mt6370_bl_ops, &props); + if (IS_ERR(priv->bl)) + return dev_err_probe(dev, PTR_ERR(priv->bl), + "Failed to register backlight\n"); + + backlight_update_status(priv->bl); + platform_set_drvdata(pdev, priv); + + return 0; +} + +static void 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); +} + +static const struct of_device_id mt6370_bl_of_match[] = { + { .compatible = "mediatek,mt6370-backlight", .data = (void *)MT6370_VID_COMMON }, + { .compatible = "mediatek,mt6372-backlight", .data = (void *)MT6370_VID_6372 }, + {} +}; +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 "); +MODULE_DESCRIPTION("MediaTek MT6370 Backlight Driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1