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-pcf8583.c | 317 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 317 insertions(+) create mode 100644 drivers/rtc/rtc-pcf8583.c (limited to 'drivers/rtc/rtc-pcf8583.c') diff --git a/drivers/rtc/rtc-pcf8583.c b/drivers/rtc/rtc-pcf8583.c new file mode 100644 index 000000000..df5e20cbc --- /dev/null +++ b/drivers/rtc/rtc-pcf8583.c @@ -0,0 +1,317 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * drivers/rtc/rtc-pcf8583.c + * + * Copyright (C) 2000 Russell King + * Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix + * + * Driver for PCF8583 RTC & RAM chip + * + * Converted to the generic RTC susbsystem by G. Liakhovetski (2006) + */ +#include +#include +#include +#include +#include +#include +#include +#include + +struct rtc_mem { + unsigned int loc; + unsigned int nr; + unsigned char *data; +}; + +struct pcf8583 { + struct rtc_device *rtc; + unsigned char ctrl; +}; + +#define CTRL_STOP 0x80 +#define CTRL_HOLD 0x40 +#define CTRL_32KHZ 0x00 +#define CTRL_MASK 0x08 +#define CTRL_ALARMEN 0x04 +#define CTRL_ALARM 0x02 +#define CTRL_TIMER 0x01 + + +static struct i2c_driver pcf8583_driver; + +#define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl +#define set_ctrl(x, v) get_ctrl(x) = v + +#define CMOS_YEAR (64 + 128) +#define CMOS_CHECKSUM (63) + +static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt) +{ + unsigned char buf[8], addr[1] = { 1 }; + struct i2c_msg msgs[2] = { + { + .addr = client->addr, + .flags = 0, + .len = 1, + .buf = addr, + }, { + .addr = client->addr, + .flags = I2C_M_RD, + .len = 6, + .buf = buf, + } + }; + int ret; + + memset(buf, 0, sizeof(buf)); + + ret = i2c_transfer(client->adapter, msgs, 2); + if (ret == 2) { + dt->tm_year = buf[4] >> 6; + dt->tm_wday = buf[5] >> 5; + + buf[4] &= 0x3f; + buf[5] &= 0x1f; + + dt->tm_sec = bcd2bin(buf[1]); + dt->tm_min = bcd2bin(buf[2]); + dt->tm_hour = bcd2bin(buf[3]); + dt->tm_mday = bcd2bin(buf[4]); + dt->tm_mon = bcd2bin(buf[5]) - 1; + } + + return ret == 2 ? 0 : -EIO; +} + +static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo) +{ + unsigned char buf[8]; + int ret, len = 6; + + buf[0] = 0; + buf[1] = get_ctrl(client) | 0x80; + buf[2] = 0; + buf[3] = bin2bcd(dt->tm_sec); + buf[4] = bin2bcd(dt->tm_min); + buf[5] = bin2bcd(dt->tm_hour); + + if (datetoo) { + len = 8; + buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6); + buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5); + } + + ret = i2c_master_send(client, (char *)buf, len); + if (ret != len) + return -EIO; + + buf[1] = get_ctrl(client); + ret = i2c_master_send(client, (char *)buf, 2); + + return ret == 2 ? 0 : -EIO; +} + +static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl) +{ + *ctrl = get_ctrl(client); + return 0; +} + +static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl) +{ + unsigned char buf[2]; + + buf[0] = 0; + buf[1] = *ctrl; + set_ctrl(client, *ctrl); + + return i2c_master_send(client, (char *)buf, 2); +} + +static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem) +{ + unsigned char addr[1]; + struct i2c_msg msgs[2] = { + { + .addr = client->addr, + .flags = 0, + .len = 1, + .buf = addr, + }, { + .addr = client->addr, + .flags = I2C_M_RD, + .len = mem->nr, + .buf = mem->data, + } + }; + + if (mem->loc < 8) + return -EINVAL; + + addr[0] = mem->loc; + + return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO; +} + +static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem) +{ + unsigned char buf[9]; + int ret; + + if (mem->loc < 8 || mem->nr > 8) + return -EINVAL; + + buf[0] = mem->loc; + memcpy(buf + 1, mem->data, mem->nr); + + ret = i2c_master_send(client, buf, mem->nr + 1); + return ret == mem->nr + 1 ? 0 : -EIO; +} + +static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + unsigned char ctrl, year[2]; + struct rtc_mem mem = { + .loc = CMOS_YEAR, + .nr = sizeof(year), + .data = year + }; + int real_year, year_offset, err; + + /* + * Ensure that the RTC is running. + */ + pcf8583_get_ctrl(client, &ctrl); + if (ctrl & (CTRL_STOP | CTRL_HOLD)) { + unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD); + + dev_warn(dev, "resetting control %02x -> %02x\n", + ctrl, new_ctrl); + + err = pcf8583_set_ctrl(client, &new_ctrl); + if (err < 0) + return err; + } + + if (pcf8583_get_datetime(client, tm) || + pcf8583_read_mem(client, &mem)) + return -EIO; + + real_year = year[0]; + + /* + * The RTC year holds the LSB two bits of the current + * year, which should reflect the LSB two bits of the + * CMOS copy of the year. Any difference indicates + * that we have to correct the CMOS version. + */ + year_offset = tm->tm_year - (real_year & 3); + if (year_offset < 0) + /* + * RTC year wrapped. Adjust it appropriately. + */ + year_offset += 4; + + tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900; + + return 0; +} + +static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + unsigned char year[2], chk; + struct rtc_mem cmos_year = { + .loc = CMOS_YEAR, + .nr = sizeof(year), + .data = year + }; + struct rtc_mem cmos_check = { + .loc = CMOS_CHECKSUM, + .nr = 1, + .data = &chk + }; + unsigned int proper_year = tm->tm_year + 1900; + int ret; + + /* + * The RTC's own 2-bit year must reflect the least + * significant two bits of the CMOS year. + */ + + ret = pcf8583_set_datetime(client, tm, 1); + if (ret) + return ret; + + ret = pcf8583_read_mem(client, &cmos_check); + if (ret) + return ret; + + ret = pcf8583_read_mem(client, &cmos_year); + if (ret) + return ret; + + chk -= year[1] + year[0]; + + year[1] = proper_year / 100; + year[0] = proper_year % 100; + + chk += year[1] + year[0]; + + ret = pcf8583_write_mem(client, &cmos_year); + + if (ret) + return ret; + + ret = pcf8583_write_mem(client, &cmos_check); + + return ret; +} + +static const struct rtc_class_ops pcf8583_rtc_ops = { + .read_time = pcf8583_rtc_read_time, + .set_time = pcf8583_rtc_set_time, +}; + +static int pcf8583_probe(struct i2c_client *client) +{ + struct pcf8583 *pcf8583; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583), + GFP_KERNEL); + if (!pcf8583) + return -ENOMEM; + + i2c_set_clientdata(client, pcf8583); + + pcf8583->rtc = devm_rtc_device_register(&client->dev, + pcf8583_driver.driver.name, + &pcf8583_rtc_ops, THIS_MODULE); + + return PTR_ERR_OR_ZERO(pcf8583->rtc); +} + +static const struct i2c_device_id pcf8583_id[] = { + { .name = "pcf8583" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, pcf8583_id); + +static struct i2c_driver pcf8583_driver = { + .driver = { + .name = "pcf8583", + }, + .probe = pcf8583_probe, + .id_table = pcf8583_id, +}; + +module_i2c_driver(pcf8583_driver); + +MODULE_AUTHOR("Russell King"); +MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1