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/rtc/rtc-sd2405al.c | 229 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 229 insertions(+) create mode 100644 drivers/rtc/rtc-sd2405al.c (limited to 'drivers/rtc/rtc-sd2405al.c') diff --git a/drivers/rtc/rtc-sd2405al.c b/drivers/rtc/rtc-sd2405al.c new file mode 100644 index 000000000..7982a910a --- /dev/null +++ b/drivers/rtc/rtc-sd2405al.c @@ -0,0 +1,229 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * RTC driver for the SD2405AL Real-Time Clock + * + * Datasheet: + * https://image.dfrobot.com/image/data/TOY0021/SD2405AL%20datasheet%20(Angelo%20v0.1).pdf + * + * I2C slave address: 0x32 + * + * Copyright (C) 2024-2025 Tóth János + */ + +#include +#include +#include +#include + +/* Real time clock registers */ +#define SD2405AL_REG_T_SEC 0x00 +#define SD2405AL_REG_T_MIN 0x01 +#define SD2405AL_REG_T_HOUR 0x02 +# define SD2405AL_BIT_12H_PM BIT(5) +# define SD2405AL_BIT_24H BIT(7) +#define SD2405AL_REG_T_WEEK 0x03 +#define SD2405AL_REG_T_DAY 0x04 +#define SD2405AL_REG_T_MON 0x05 +#define SD2405AL_REG_T_YEAR 0x06 + +#define SD2405AL_NUM_T_REGS (SD2405AL_REG_T_YEAR - SD2405AL_REG_T_SEC + 1) + +/* Control registers */ +#define SD2405AL_REG_CTR1 0x0F +# define SD2405AL_BIT_WRTC2 BIT(2) +# define SD2405AL_BIT_WRTC3 BIT(7) +#define SD2405AL_REG_CTR2 0x10 +# define SD2405AL_BIT_WRTC1 BIT(7) +#define SD2405AL_REG_CTR3 0x11 +#define SD2405AL_REG_TTF 0x12 +#define SD2405AL_REG_CNTDWN 0x13 + +/* General RAM */ +#define SD2405AL_REG_M_START 0x14 +#define SD2405AL_REG_M_END 0x1F + +struct sd2405al { + struct device *dev; + struct regmap *regmap; +}; + +static int sd2405al_enable_reg_write(struct sd2405al *sd2405al) +{ + int ret; + + /* order of writes is important */ + ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2, + SD2405AL_BIT_WRTC1, SD2405AL_BIT_WRTC1); + if (ret < 0) + return ret; + + ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1, + SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, + SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3); + if (ret < 0) + return ret; + + return 0; +} + +static int sd2405al_disable_reg_write(struct sd2405al *sd2405al) +{ + int ret; + + /* order of writes is important */ + ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1, + SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, 0x00); + if (ret < 0) + return ret; + + ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2, + SD2405AL_BIT_WRTC1, 0x00); + if (ret < 0) + return ret; + + return 0; +} + +static int sd2405al_read_time(struct device *dev, struct rtc_time *time) +{ + u8 data[SD2405AL_NUM_T_REGS] = { 0 }; + struct sd2405al *sd2405al = dev_get_drvdata(dev); + int ret; + + ret = regmap_bulk_read(sd2405al->regmap, SD2405AL_REG_T_SEC, data, + SD2405AL_NUM_T_REGS); + if (ret < 0) + return ret; + + time->tm_sec = bcd2bin(data[SD2405AL_REG_T_SEC] & 0x7F); + time->tm_min = bcd2bin(data[SD2405AL_REG_T_MIN] & 0x7F); + + if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_24H) + time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] & 0x3F); + else + if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_12H_PM) + time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] + & 0x1F) + 12; + else /* 12 hour mode, AM */ + time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] + & 0x1F); + + time->tm_wday = bcd2bin(data[SD2405AL_REG_T_WEEK] & 0x07); + time->tm_mday = bcd2bin(data[SD2405AL_REG_T_DAY] & 0x3F); + time->tm_mon = bcd2bin(data[SD2405AL_REG_T_MON] & 0x1F) - 1; + time->tm_year = bcd2bin(data[SD2405AL_REG_T_YEAR]) + 100; + + dev_dbg(sd2405al->dev, "read time: %ptR (%d)\n", time, time->tm_wday); + + return 0; +} + +static int sd2405al_set_time(struct device *dev, struct rtc_time *time) +{ + u8 data[SD2405AL_NUM_T_REGS]; + struct sd2405al *sd2405al = dev_get_drvdata(dev); + int ret; + + data[SD2405AL_REG_T_SEC] = bin2bcd(time->tm_sec); + data[SD2405AL_REG_T_MIN] = bin2bcd(time->tm_min); + data[SD2405AL_REG_T_HOUR] = bin2bcd(time->tm_hour) | SD2405AL_BIT_24H; + data[SD2405AL_REG_T_DAY] = bin2bcd(time->tm_mday); + data[SD2405AL_REG_T_WEEK] = bin2bcd(time->tm_wday); + data[SD2405AL_REG_T_MON] = bin2bcd(time->tm_mon) + 1; + data[SD2405AL_REG_T_YEAR] = bin2bcd(time->tm_year - 100); + + ret = sd2405al_enable_reg_write(sd2405al); + if (ret < 0) + return ret; + + ret = regmap_bulk_write(sd2405al->regmap, SD2405AL_REG_T_SEC, data, + SD2405AL_NUM_T_REGS); + if (ret < 0) + return ret; + + ret = regmap_write(sd2405al->regmap, SD2405AL_REG_TTF, 0x00); + if (ret < 0) + return ret; + + ret = sd2405al_disable_reg_write(sd2405al); + if (ret < 0) + return ret; + + dev_dbg(sd2405al->dev, "set time: %ptR (%d)\n", time, time->tm_wday); + + return 0; +} + +static const struct rtc_class_ops sd2405al_rtc_ops = { + .read_time = sd2405al_read_time, + .set_time = sd2405al_set_time, +}; + +static const struct regmap_config sd2405al_regmap_conf = { + .reg_bits = 8, + .val_bits = 8, + .max_register = SD2405AL_REG_M_END, +}; + +static int sd2405al_probe(struct i2c_client *client) +{ + struct sd2405al *sd2405al; + struct rtc_device *rtc; + int ret; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + sd2405al = devm_kzalloc(&client->dev, sizeof(*sd2405al), GFP_KERNEL); + if (!sd2405al) + return -ENOMEM; + + sd2405al->dev = &client->dev; + + sd2405al->regmap = devm_regmap_init_i2c(client, &sd2405al_regmap_conf); + if (IS_ERR(sd2405al->regmap)) + return PTR_ERR(sd2405al->regmap); + + rtc = devm_rtc_allocate_device(&client->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + rtc->ops = &sd2405al_rtc_ops; + rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; + rtc->range_max = RTC_TIMESTAMP_END_2099; + + dev_set_drvdata(&client->dev, sd2405al); + + ret = devm_rtc_register_device(rtc); + if (ret < 0) + return ret; + + return 0; +} + +static const struct i2c_device_id sd2405al_id[] = { + { .name = "sd2405al" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(i2c, sd2405al_id); + +static const __maybe_unused struct of_device_id sd2405al_of_match[] = { + { .compatible = "dfrobot,sd2405al" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, sd2405al_of_match); + +static struct i2c_driver sd2405al_driver = { + .driver = { + .name = "sd2405al", + .of_match_table = of_match_ptr(sd2405al_of_match), + }, + .probe = sd2405al_probe, + .id_table = sd2405al_id, +}; + +module_i2c_driver(sd2405al_driver); + +MODULE_AUTHOR("Tóth János "); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("SD2405AL RTC driver"); -- cgit v1.3.1