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-r9701.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 drivers/rtc/rtc-r9701.c (limited to 'drivers/rtc/rtc-r9701.c') diff --git a/drivers/rtc/rtc-r9701.c b/drivers/rtc/rtc-r9701.c new file mode 100644 index 000000000..60a3c3d74 --- /dev/null +++ b/drivers/rtc/rtc-r9701.c @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for Epson RTC-9701JE + * + * Copyright (C) 2008 Magnus Damm + * + * Based on rtc-max6902.c + * + * Copyright (C) 2006 8D Technologies inc. + * Copyright (C) 2004 Compulab Ltd. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define RSECCNT 0x00 /* Second Counter */ +#define RMINCNT 0x01 /* Minute Counter */ +#define RHRCNT 0x02 /* Hour Counter */ +#define RWKCNT 0x03 /* Week Counter */ +#define RDAYCNT 0x04 /* Day Counter */ +#define RMONCNT 0x05 /* Month Counter */ +#define RYRCNT 0x06 /* Year Counter */ +#define R100CNT 0x07 /* Y100 Counter */ +#define RMINAR 0x08 /* Minute Alarm */ +#define RHRAR 0x09 /* Hour Alarm */ +#define RWKAR 0x0a /* Week/Day Alarm */ +#define RTIMCNT 0x0c /* Interval Timer */ +#define REXT 0x0d /* Extension Register */ +#define RFLAG 0x0e /* RTC Flag Register */ +#define RCR 0x0f /* RTC Control Register */ + +static int write_reg(struct device *dev, int address, unsigned char data) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[2]; + + buf[0] = address & 0x7f; + buf[1] = data; + + return spi_write(spi, buf, ARRAY_SIZE(buf)); +} + +static int read_regs(struct device *dev, unsigned char *regs, int no_regs) +{ + struct spi_device *spi = to_spi_device(dev); + u8 txbuf[1], rxbuf[1]; + int k, ret; + + ret = 0; + + for (k = 0; ret == 0 && k < no_regs; k++) { + txbuf[0] = 0x80 | regs[k]; + ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1); + regs[k] = rxbuf[0]; + } + + return ret; +} + +static int r9701_get_datetime(struct device *dev, struct rtc_time *dt) +{ + int ret; + unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT, + RDAYCNT, RMONCNT, RYRCNT }; + + ret = read_regs(dev, buf, ARRAY_SIZE(buf)); + if (ret) + return ret; + + dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */ + dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */ + dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */ + + dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */ + dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */ + dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */ + + return 0; +} + +static int r9701_set_datetime(struct device *dev, struct rtc_time *dt) +{ + int ret; + + ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour)); + ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min)); + ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec)); + ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday)); + ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1)); + ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100)); + + return ret; +} + +static const struct rtc_class_ops r9701_rtc_ops = { + .read_time = r9701_get_datetime, + .set_time = r9701_set_datetime, +}; + +static int r9701_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + unsigned char tmp; + int res; + + tmp = R100CNT; + res = read_regs(&spi->dev, &tmp, 1); + if (res || tmp != 0x20) { + dev_err(&spi->dev, "cannot read RTC register\n"); + return -ENODEV; + } + + rtc = devm_rtc_allocate_device(&spi->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + spi_set_drvdata(spi, rtc); + rtc->ops = &r9701_rtc_ops; + rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; + rtc->range_max = RTC_TIMESTAMP_END_2099; + + return devm_rtc_register_device(rtc); +} + +static struct spi_driver r9701_driver = { + .driver = { + .name = "rtc-r9701", + }, + .probe = r9701_probe, +}; + +module_spi_driver(r9701_driver); + +MODULE_DESCRIPTION("r9701 spi RTC driver"); +MODULE_AUTHOR("Magnus Damm "); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:rtc-r9701"); -- cgit v1.3.1