From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- drivers/rtc/rtc-max8925.c | 322 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 322 insertions(+) create mode 100644 drivers/rtc/rtc-max8925.c (limited to 'drivers/rtc/rtc-max8925.c') diff --git a/drivers/rtc/rtc-max8925.c b/drivers/rtc/rtc-max8925.c new file mode 100644 index 000000000..6ce8afbea --- /dev/null +++ b/drivers/rtc/rtc-max8925.c @@ -0,0 +1,322 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * RTC driver for Maxim MAX8925 + * + * Copyright (C) 2009-2010 Marvell International Ltd. + * Haojian Zhuang + */ + +#include +#include +#include +#include +#include +#include + +enum { + RTC_SEC = 0, + RTC_MIN, + RTC_HOUR, + RTC_WEEKDAY, + RTC_DATE, + RTC_MONTH, + RTC_YEAR1, + RTC_YEAR2, +}; + +#define MAX8925_RTC_SEC 0x00 +#define MAX8925_RTC_MIN 0x01 +#define MAX8925_RTC_HOUR 0x02 +#define MAX8925_RTC_WEEKDAY 0x03 +#define MAX8925_RTC_DATE 0x04 +#define MAX8925_RTC_MONTH 0x05 +#define MAX8925_RTC_YEAR1 0x06 +#define MAX8925_RTC_YEAR2 0x07 +#define MAX8925_ALARM0_SEC 0x08 +#define MAX8925_ALARM0_MIN 0x09 +#define MAX8925_ALARM0_HOUR 0x0a +#define MAX8925_ALARM0_WEEKDAY 0x0b +#define MAX8925_ALARM0_DATE 0x0c +#define MAX8925_ALARM0_MON 0x0d +#define MAX8925_ALARM0_YEAR1 0x0e +#define MAX8925_ALARM0_YEAR2 0x0f +#define MAX8925_ALARM1_SEC 0x10 +#define MAX8925_ALARM1_MIN 0x11 +#define MAX8925_ALARM1_HOUR 0x12 +#define MAX8925_ALARM1_WEEKDAY 0x13 +#define MAX8925_ALARM1_DATE 0x14 +#define MAX8925_ALARM1_MON 0x15 +#define MAX8925_ALARM1_YEAR1 0x16 +#define MAX8925_ALARM1_YEAR2 0x17 +#define MAX8925_RTC_CNTL 0x1b +#define MAX8925_RTC_STATUS 0x20 + +#define TIME_NUM 8 +#define ALARM_1SEC (1 << 7) +#define HOUR_12 (1 << 7) +#define HOUR_AM_PM (1 << 5) +#define ALARM0_IRQ (1 << 3) +#define ALARM1_IRQ (1 << 2) +#define ALARM0_STATUS (1 << 2) +#define ALARM1_STATUS (1 << 1) + + +struct max8925_rtc_info { + struct rtc_device *rtc_dev; + struct max8925_chip *chip; + struct i2c_client *rtc; + struct device *dev; + int irq; +}; + +static irqreturn_t rtc_update_handler(int irq, void *data) +{ + struct max8925_rtc_info *info = (struct max8925_rtc_info *)data; + + /* disable ALARM0 except for 1SEC alarm */ + max8925_set_bits(info->rtc, MAX8925_ALARM0_CNTL, 0x7f, 0); + rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF); + return IRQ_HANDLED; +} + +static int tm_calc(struct rtc_time *tm, unsigned char *buf, int len) +{ + if (len < TIME_NUM) + return -EINVAL; + tm->tm_year = (buf[RTC_YEAR2] >> 4) * 1000 + + (buf[RTC_YEAR2] & 0xf) * 100 + + (buf[RTC_YEAR1] >> 4) * 10 + + (buf[RTC_YEAR1] & 0xf); + tm->tm_year -= 1900; + tm->tm_mon = ((buf[RTC_MONTH] >> 4) & 0x01) * 10 + + (buf[RTC_MONTH] & 0x0f); + tm->tm_mday = ((buf[RTC_DATE] >> 4) & 0x03) * 10 + + (buf[RTC_DATE] & 0x0f); + tm->tm_wday = buf[RTC_WEEKDAY] & 0x07; + if (buf[RTC_HOUR] & HOUR_12) { + tm->tm_hour = ((buf[RTC_HOUR] >> 4) & 0x1) * 10 + + (buf[RTC_HOUR] & 0x0f); + if (buf[RTC_HOUR] & HOUR_AM_PM) + tm->tm_hour += 12; + } else + tm->tm_hour = ((buf[RTC_HOUR] >> 4) & 0x03) * 10 + + (buf[RTC_HOUR] & 0x0f); + tm->tm_min = ((buf[RTC_MIN] >> 4) & 0x7) * 10 + + (buf[RTC_MIN] & 0x0f); + tm->tm_sec = ((buf[RTC_SEC] >> 4) & 0x7) * 10 + + (buf[RTC_SEC] & 0x0f); + return 0; +} + +static int data_calc(unsigned char *buf, struct rtc_time *tm, int len) +{ + unsigned char high, low; + + if (len < TIME_NUM) + return -EINVAL; + + high = (tm->tm_year + 1900) / 1000; + low = (tm->tm_year + 1900) / 100; + low = low - high * 10; + buf[RTC_YEAR2] = (high << 4) + low; + high = (tm->tm_year + 1900) / 10; + low = tm->tm_year + 1900; + low = low - high * 10; + high = high - (high / 10) * 10; + buf[RTC_YEAR1] = (high << 4) + low; + high = tm->tm_mon / 10; + low = tm->tm_mon; + low = low - high * 10; + buf[RTC_MONTH] = (high << 4) + low; + high = tm->tm_mday / 10; + low = tm->tm_mday; + low = low - high * 10; + buf[RTC_DATE] = (high << 4) + low; + buf[RTC_WEEKDAY] = tm->tm_wday; + high = tm->tm_hour / 10; + low = tm->tm_hour; + low = low - high * 10; + buf[RTC_HOUR] = (high << 4) + low; + high = tm->tm_min / 10; + low = tm->tm_min; + low = low - high * 10; + buf[RTC_MIN] = (high << 4) + low; + high = tm->tm_sec / 10; + low = tm->tm_sec; + low = low - high * 10; + buf[RTC_SEC] = (high << 4) + low; + return 0; +} + +static int max8925_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct max8925_rtc_info *info = dev_get_drvdata(dev); + unsigned char buf[TIME_NUM]; + int ret; + + ret = max8925_bulk_read(info->rtc, MAX8925_RTC_SEC, TIME_NUM, buf); + if (ret < 0) + goto out; + ret = tm_calc(tm, buf, TIME_NUM); +out: + return ret; +} + +static int max8925_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct max8925_rtc_info *info = dev_get_drvdata(dev); + unsigned char buf[TIME_NUM]; + int ret; + + ret = data_calc(buf, tm, TIME_NUM); + if (ret < 0) + goto out; + ret = max8925_bulk_write(info->rtc, MAX8925_RTC_SEC, TIME_NUM, buf); +out: + return ret; +} + +static int max8925_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) +{ + struct max8925_rtc_info *info = dev_get_drvdata(dev); + unsigned char buf[TIME_NUM]; + int ret; + + ret = max8925_bulk_read(info->rtc, MAX8925_ALARM0_SEC, TIME_NUM, buf); + if (ret < 0) + goto out; + ret = tm_calc(&alrm->time, buf, TIME_NUM); + if (ret < 0) + goto out; + ret = max8925_reg_read(info->rtc, MAX8925_RTC_IRQ_MASK); + if (ret < 0) + goto out; + if (ret & ALARM0_IRQ) { + alrm->enabled = 0; + } else { + ret = max8925_reg_read(info->rtc, MAX8925_ALARM0_CNTL); + if (ret < 0) + goto out; + if (!ret) + alrm->enabled = 0; + else + alrm->enabled = 1; + } + ret = max8925_reg_read(info->rtc, MAX8925_RTC_STATUS); + if (ret < 0) + goto out; + if (ret & ALARM0_STATUS) + alrm->pending = 1; + else + alrm->pending = 0; + return 0; +out: + return ret; +} + +static int max8925_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) +{ + struct max8925_rtc_info *info = dev_get_drvdata(dev); + unsigned char buf[TIME_NUM]; + int ret; + + ret = data_calc(buf, &alrm->time, TIME_NUM); + if (ret < 0) + goto out; + ret = max8925_bulk_write(info->rtc, MAX8925_ALARM0_SEC, TIME_NUM, buf); + if (ret < 0) + goto out; + if (alrm->enabled) + /* only enable alarm on year/month/day/hour/min/sec */ + ret = max8925_reg_write(info->rtc, MAX8925_ALARM0_CNTL, 0x77); + else + ret = max8925_reg_write(info->rtc, MAX8925_ALARM0_CNTL, 0x0); +out: + return ret; +} + +static const struct rtc_class_ops max8925_rtc_ops = { + .read_time = max8925_rtc_read_time, + .set_time = max8925_rtc_set_time, + .read_alarm = max8925_rtc_read_alarm, + .set_alarm = max8925_rtc_set_alarm, +}; + +static int max8925_rtc_probe(struct platform_device *pdev) +{ + struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent); + struct max8925_rtc_info *info; + int ret; + + info = devm_kzalloc(&pdev->dev, sizeof(struct max8925_rtc_info), + GFP_KERNEL); + if (!info) + return -ENOMEM; + info->chip = chip; + info->rtc = chip->rtc; + info->dev = &pdev->dev; + info->irq = platform_get_irq(pdev, 0); + + ret = devm_request_threaded_irq(&pdev->dev, info->irq, NULL, + rtc_update_handler, IRQF_ONESHOT, + "rtc-alarm0", info); + if (ret < 0) { + dev_err(chip->dev, "Failed to request IRQ: #%d: %d\n", + info->irq, ret); + return ret; + } + + dev_set_drvdata(&pdev->dev, info); + /* XXX - isn't this redundant? */ + platform_set_drvdata(pdev, info); + + device_init_wakeup(&pdev->dev, true); + + info->rtc_dev = devm_rtc_device_register(&pdev->dev, "max8925-rtc", + &max8925_rtc_ops, THIS_MODULE); + ret = PTR_ERR(info->rtc_dev); + if (IS_ERR(info->rtc_dev)) { + dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret); + return ret; + } + + return 0; +} + +#ifdef CONFIG_PM_SLEEP +static int max8925_rtc_suspend(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent); + + if (device_may_wakeup(dev)) + chip->wakeup_flag |= 1 << MAX8925_IRQ_RTC_ALARM0; + return 0; +} +static int max8925_rtc_resume(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent); + + if (device_may_wakeup(dev)) + chip->wakeup_flag &= ~(1 << MAX8925_IRQ_RTC_ALARM0); + return 0; +} +#endif + +static SIMPLE_DEV_PM_OPS(max8925_rtc_pm_ops, max8925_rtc_suspend, max8925_rtc_resume); + +static struct platform_driver max8925_rtc_driver = { + .driver = { + .name = "max8925-rtc", + .pm = &max8925_rtc_pm_ops, + }, + .probe = max8925_rtc_probe, +}; + +module_platform_driver(max8925_rtc_driver); + +MODULE_DESCRIPTION("Maxim MAX8925 RTC driver"); +MODULE_AUTHOR("Haojian Zhuang "); +MODULE_LICENSE("GPL"); + -- cgit v1.3.1