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-ds1390.c | 242 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 242 insertions(+) create mode 100644 drivers/rtc/rtc-ds1390.c (limited to 'drivers/rtc/rtc-ds1390.c') diff --git a/drivers/rtc/rtc-ds1390.c b/drivers/rtc/rtc-ds1390.c new file mode 100644 index 000000000..f7afd6bde --- /dev/null +++ b/drivers/rtc/rtc-ds1390.c @@ -0,0 +1,242 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC + * + * Copyright (C) 2008 Mercury IMC Ltd + * Written by Mark Jackson + * + * NOTE: Currently this driver only supports the bare minimum for read + * and write the RTC. The extra features provided by the chip family + * (alarms, trickle charger, different control registers) are unavailable. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#define DS1390_REG_100THS 0x00 +#define DS1390_REG_SECONDS 0x01 +#define DS1390_REG_MINUTES 0x02 +#define DS1390_REG_HOURS 0x03 +#define DS1390_REG_DAY 0x04 +#define DS1390_REG_DATE 0x05 +#define DS1390_REG_MONTH_CENT 0x06 +#define DS1390_REG_YEAR 0x07 + +#define DS1390_REG_ALARM_100THS 0x08 +#define DS1390_REG_ALARM_SECONDS 0x09 +#define DS1390_REG_ALARM_MINUTES 0x0A +#define DS1390_REG_ALARM_HOURS 0x0B +#define DS1390_REG_ALARM_DAY_DATE 0x0C + +#define DS1390_REG_CONTROL 0x0D +#define DS1390_REG_STATUS 0x0E +#define DS1390_REG_TRICKLE 0x0F + +#define DS1390_TRICKLE_CHARGER_ENABLE 0xA0 +#define DS1390_TRICKLE_CHARGER_250_OHM 0x01 +#define DS1390_TRICKLE_CHARGER_2K_OHM 0x02 +#define DS1390_TRICKLE_CHARGER_4K_OHM 0x03 +#define DS1390_TRICKLE_CHARGER_NO_DIODE 0x04 +#define DS1390_TRICKLE_CHARGER_DIODE 0x08 + +struct ds1390 { + struct rtc_device *rtc; + u8 txrx_buf[9]; /* cmd + 8 registers */ +}; + +static void ds1390_set_reg(struct device *dev, unsigned char address, + unsigned char data) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[2]; + + /* MSB must be '1' to write */ + buf[0] = address | 0x80; + buf[1] = data; + + spi_write(spi, buf, 2); +} + +static int ds1390_get_reg(struct device *dev, unsigned char address, + unsigned char *data) +{ + struct spi_device *spi = to_spi_device(dev); + struct ds1390 *chip = dev_get_drvdata(dev); + int status; + + if (!data) + return -EINVAL; + + /* Clear MSB to indicate read */ + chip->txrx_buf[0] = address & 0x7f; + /* do the i/o */ + status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1); + if (status != 0) + return status; + + *data = chip->txrx_buf[0]; + + return 0; +} + +static void ds1390_trickle_of_init(struct spi_device *spi) +{ + u32 ohms = 0; + u8 value; + + if (of_property_read_u32(spi->dev.of_node, "trickle-resistor-ohms", + &ohms)) + goto out; + + /* Enable charger */ + value = DS1390_TRICKLE_CHARGER_ENABLE; + if (of_property_read_bool(spi->dev.of_node, "trickle-diode-disable")) + value |= DS1390_TRICKLE_CHARGER_NO_DIODE; + else + value |= DS1390_TRICKLE_CHARGER_DIODE; + + /* Resistor select */ + switch (ohms) { + case 250: + value |= DS1390_TRICKLE_CHARGER_250_OHM; + break; + case 2000: + value |= DS1390_TRICKLE_CHARGER_2K_OHM; + break; + case 4000: + value |= DS1390_TRICKLE_CHARGER_4K_OHM; + break; + default: + dev_warn(&spi->dev, + "Unsupported ohm value %02ux in dt\n", ohms); + return; + } + + ds1390_set_reg(&spi->dev, DS1390_REG_TRICKLE, value); + +out: + return; +} + +static int ds1390_read_time(struct device *dev, struct rtc_time *dt) +{ + struct spi_device *spi = to_spi_device(dev); + struct ds1390 *chip = dev_get_drvdata(dev); + int status; + + /* build the message */ + chip->txrx_buf[0] = DS1390_REG_SECONDS; + + /* do the i/o */ + status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 7); + if (status != 0) + return status; + + /* The chip sends data in this order: + * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */ + dt->tm_sec = bcd2bin(chip->txrx_buf[0]); + dt->tm_min = bcd2bin(chip->txrx_buf[1]); + dt->tm_hour = bcd2bin(chip->txrx_buf[2]); + dt->tm_wday = bcd2bin(chip->txrx_buf[3]); + dt->tm_mday = bcd2bin(chip->txrx_buf[4]); + /* mask off century bit */ + dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1; + /* adjust for century bit */ + dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0); + + return 0; +} + +static int ds1390_set_time(struct device *dev, struct rtc_time *dt) +{ + struct spi_device *spi = to_spi_device(dev); + struct ds1390 *chip = dev_get_drvdata(dev); + + /* build the message */ + chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80; + chip->txrx_buf[1] = bin2bcd(dt->tm_sec); + chip->txrx_buf[2] = bin2bcd(dt->tm_min); + chip->txrx_buf[3] = bin2bcd(dt->tm_hour); + chip->txrx_buf[4] = bin2bcd(dt->tm_wday); + chip->txrx_buf[5] = bin2bcd(dt->tm_mday); + chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) | + ((dt->tm_year > 99) ? 0x80 : 0x00); + chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100); + + /* do the i/o */ + return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0); +} + +static const struct rtc_class_ops ds1390_rtc_ops = { + .read_time = ds1390_read_time, + .set_time = ds1390_set_time, +}; + +static int ds1390_probe(struct spi_device *spi) +{ + unsigned char tmp; + struct ds1390 *chip; + int res; + + spi->mode = SPI_MODE_3; + spi->bits_per_word = 8; + spi_setup(spi); + + chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL); + if (!chip) + return -ENOMEM; + + spi_set_drvdata(spi, chip); + + res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp); + if (res != 0) { + dev_err(&spi->dev, "unable to read device\n"); + return res; + } + + if (spi->dev.of_node) + ds1390_trickle_of_init(spi); + + chip->rtc = devm_rtc_device_register(&spi->dev, "ds1390", + &ds1390_rtc_ops, THIS_MODULE); + if (IS_ERR(chip->rtc)) { + dev_err(&spi->dev, "unable to register device\n"); + res = PTR_ERR(chip->rtc); + } + + return res; +} + +static const struct of_device_id ds1390_of_match[] __maybe_unused = { + { .compatible = "dallas,ds1390" }, + {} +}; +MODULE_DEVICE_TABLE(of, ds1390_of_match); + +static const struct spi_device_id ds1390_spi_ids[] = { + { .name = "ds1390" }, + {} +}; +MODULE_DEVICE_TABLE(spi, ds1390_spi_ids); + +static struct spi_driver ds1390_driver = { + .driver = { + .name = "rtc-ds1390", + .of_match_table = of_match_ptr(ds1390_of_match), + }, + .probe = ds1390_probe, + .id_table = ds1390_spi_ids, +}; + +module_spi_driver(ds1390_driver); + +MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver"); +MODULE_AUTHOR("Mark Jackson "); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:rtc-ds1390"); -- cgit v1.3.1