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-ds1347.c | 183 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 183 insertions(+) create mode 100644 drivers/rtc/rtc-ds1347.c (limited to 'drivers/rtc/rtc-ds1347.c') diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c new file mode 100644 index 000000000..a40c1a52d --- /dev/null +++ b/drivers/rtc/rtc-ds1347.c @@ -0,0 +1,183 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* rtc-ds1347.c + * + * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible + * Real Time Clock + * + * Author : Raghavendra Chandra Ganiga + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +/* Registers in ds1347 rtc */ + +#define DS1347_SECONDS_REG 0x01 +#define DS1347_MINUTES_REG 0x03 +#define DS1347_HOURS_REG 0x05 +#define DS1347_DATE_REG 0x07 +#define DS1347_MONTH_REG 0x09 +#define DS1347_DAY_REG 0x0B +#define DS1347_YEAR_REG 0x0D +#define DS1347_CONTROL_REG 0x0F +#define DS1347_CENTURY_REG 0x13 +#define DS1347_STATUS_REG 0x17 +#define DS1347_CLOCK_BURST 0x3F + +#define DS1347_WP_BIT BIT(7) + +#define DS1347_NEOSC_BIT BIT(7) +#define DS1347_OSF_BIT BIT(2) + +static const struct regmap_range ds1347_ranges[] = { + { + .range_min = DS1347_SECONDS_REG, + .range_max = DS1347_STATUS_REG, + }, +}; + +static const struct regmap_access_table ds1347_access_table = { + .yes_ranges = ds1347_ranges, + .n_yes_ranges = ARRAY_SIZE(ds1347_ranges), +}; + +static int ds1347_read_time(struct device *dev, struct rtc_time *dt) +{ + struct regmap *map = dev_get_drvdata(dev); + unsigned int status, century, secs; + unsigned char buf[8]; + int err; + + err = regmap_read(map, DS1347_STATUS_REG, &status); + if (err) + return err; + + if (status & DS1347_OSF_BIT) + return -EINVAL; + + do { + err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8); + if (err) + return err; + + err = regmap_read(map, DS1347_CENTURY_REG, ¢ury); + if (err) + return err; + + err = regmap_read(map, DS1347_SECONDS_REG, &secs); + if (err) + return err; + } while (buf[0] != secs); + + dt->tm_sec = bcd2bin(buf[0]); + dt->tm_min = bcd2bin(buf[1] & 0x7f); + dt->tm_hour = bcd2bin(buf[2] & 0x3F); + dt->tm_mday = bcd2bin(buf[3]); + dt->tm_mon = bcd2bin(buf[4]) - 1; + dt->tm_wday = bcd2bin(buf[5]) - 1; + dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900; + + return 0; +} + +static int ds1347_set_time(struct device *dev, struct rtc_time *dt) +{ + struct regmap *map = dev_get_drvdata(dev); + unsigned int century; + unsigned char buf[8]; + int err; + + err = regmap_update_bits(map, DS1347_STATUS_REG, + DS1347_NEOSC_BIT, DS1347_NEOSC_BIT); + if (err) + return err; + + buf[0] = bin2bcd(dt->tm_sec); + buf[1] = bin2bcd(dt->tm_min); + buf[2] = (bin2bcd(dt->tm_hour) & 0x3F); + buf[3] = bin2bcd(dt->tm_mday); + buf[4] = bin2bcd(dt->tm_mon + 1); + buf[5] = bin2bcd(dt->tm_wday + 1); + buf[6] = bin2bcd(dt->tm_year % 100); + buf[7] = bin2bcd(0x00); + + err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8); + if (err) + return err; + + century = (dt->tm_year / 100) + 19; + err = regmap_write(map, DS1347_CENTURY_REG, bin2bcd(century)); + if (err) + return err; + + return regmap_update_bits(map, DS1347_STATUS_REG, + DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0); +} + +static const struct rtc_class_ops ds1347_rtc_ops = { + .read_time = ds1347_read_time, + .set_time = ds1347_set_time, +}; + +static int ds1347_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + struct regmap_config config; + struct regmap *map; + int err; + + memset(&config, 0, sizeof(config)); + config.reg_bits = 8; + config.val_bits = 8; + config.read_flag_mask = 0x80; + config.max_register = 0x3F; + config.wr_table = &ds1347_access_table; + + /* spi setup with ds1347 in mode 3 and bits per word as 8 */ + spi->mode = SPI_MODE_3; + spi->bits_per_word = 8; + spi_setup(spi); + + map = devm_regmap_init_spi(spi, &config); + + if (IS_ERR(map)) { + dev_err(&spi->dev, "ds1347 regmap init spi failed\n"); + return PTR_ERR(map); + } + + spi_set_drvdata(spi, map); + + /* Disable the write protect of rtc */ + err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0); + if (err) + return err; + + rtc = devm_rtc_allocate_device(&spi->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + rtc->ops = &ds1347_rtc_ops; + rtc->range_min = RTC_TIMESTAMP_BEGIN_0000; + rtc->range_max = RTC_TIMESTAMP_END_9999; + + return devm_rtc_register_device(rtc); +} + +static struct spi_driver ds1347_driver = { + .driver = { + .name = "ds1347", + }, + .probe = ds1347_probe, +}; + +module_spi_driver(ds1347_driver); + +MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER"); +MODULE_AUTHOR("Raghavendra C Ganiga "); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1