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-mpfs.c | 297 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 297 insertions(+) create mode 100644 drivers/rtc/rtc-mpfs.c (limited to 'drivers/rtc/rtc-mpfs.c') diff --git a/drivers/rtc/rtc-mpfs.c b/drivers/rtc/rtc-mpfs.c new file mode 100644 index 000000000..ece6de4a6 --- /dev/null +++ b/drivers/rtc/rtc-mpfs.c @@ -0,0 +1,297 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Microchip MPFS RTC driver + * + * Copyright (c) 2021-2022 Microchip Corporation. All rights reserved. + * + * Author: Daire McNamara + * & Conor Dooley + */ +#include "linux/bits.h" +#include "linux/iopoll.h" +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define CONTROL_REG 0x00 +#define MODE_REG 0x04 +#define PRESCALER_REG 0x08 +#define ALARM_LOWER_REG 0x0c +#define ALARM_UPPER_REG 0x10 +#define COMPARE_LOWER_REG 0x14 +#define COMPARE_UPPER_REG 0x18 +#define DATETIME_LOWER_REG 0x20 +#define DATETIME_UPPER_REG 0x24 + +#define CONTROL_RUNNING_BIT BIT(0) +#define CONTROL_START_BIT BIT(0) +#define CONTROL_STOP_BIT BIT(1) +#define CONTROL_ALARM_ON_BIT BIT(2) +#define CONTROL_ALARM_OFF_BIT BIT(3) +#define CONTROL_RESET_BIT BIT(4) +#define CONTROL_UPLOAD_BIT BIT(5) +#define CONTROL_DOWNLOAD_BIT BIT(6) +#define CONTROL_MATCH_BIT BIT(7) +#define CONTROL_WAKEUP_CLR_BIT BIT(8) +#define CONTROL_WAKEUP_SET_BIT BIT(9) +#define CONTROL_UPDATED_BIT BIT(10) + +#define MODE_CLOCK_CALENDAR BIT(0) +#define MODE_WAKE_EN BIT(1) +#define MODE_WAKE_RESET BIT(2) +#define MODE_WAKE_CONTINUE BIT(3) + +#define MAX_PRESCALER_COUNT GENMASK(25, 0) +#define DATETIME_UPPER_MASK GENMASK(29, 0) +#define ALARM_UPPER_MASK GENMASK(10, 0) + +#define UPLOAD_TIMEOUT_US 50 + +struct mpfs_rtc_dev { + struct rtc_device *rtc; + void __iomem *base; +}; + +static void mpfs_rtc_start(struct mpfs_rtc_dev *rtcdev) +{ + u32 ctrl; + + ctrl = readl(rtcdev->base + CONTROL_REG); + ctrl &= ~CONTROL_STOP_BIT; + ctrl |= CONTROL_START_BIT; + writel(ctrl, rtcdev->base + CONTROL_REG); +} + +static void mpfs_rtc_clear_irq(struct mpfs_rtc_dev *rtcdev) +{ + u32 val = readl(rtcdev->base + CONTROL_REG); + + val &= ~(CONTROL_ALARM_ON_BIT | CONTROL_STOP_BIT); + val |= CONTROL_ALARM_OFF_BIT; + writel(val, rtcdev->base + CONTROL_REG); + /* + * Ensure that the posted write to the CONTROL_REG register completed before + * returning from this function. Not doing this may result in the interrupt + * only being cleared some time after this function returns. + */ + (void)readl(rtcdev->base + CONTROL_REG); +} + +static int mpfs_rtc_readtime(struct device *dev, struct rtc_time *tm) +{ + struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev); + u64 time; + + time = readl(rtcdev->base + DATETIME_LOWER_REG); + time |= ((u64)readl(rtcdev->base + DATETIME_UPPER_REG) & DATETIME_UPPER_MASK) << 32; + rtc_time64_to_tm(time, tm); + + return 0; +} + +static int mpfs_rtc_settime(struct device *dev, struct rtc_time *tm) +{ + struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev); + u32 ctrl, prog; + u64 time; + int ret; + + time = rtc_tm_to_time64(tm); + + writel((u32)time, rtcdev->base + DATETIME_LOWER_REG); + writel((u32)(time >> 32) & DATETIME_UPPER_MASK, rtcdev->base + DATETIME_UPPER_REG); + + ctrl = readl(rtcdev->base + CONTROL_REG); + ctrl &= ~CONTROL_STOP_BIT; + ctrl |= CONTROL_UPLOAD_BIT; + writel(ctrl, rtcdev->base + CONTROL_REG); + + ret = read_poll_timeout(readl, prog, !(prog & CONTROL_UPLOAD_BIT), 0, UPLOAD_TIMEOUT_US, + false, rtcdev->base + CONTROL_REG); + if (ret) { + dev_err(dev, "timed out uploading time to rtc"); + return ret; + } + mpfs_rtc_start(rtcdev); + + return 0; +} + +static int mpfs_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) +{ + struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev); + u32 mode = readl(rtcdev->base + MODE_REG); + u64 time; + + alrm->enabled = mode & MODE_WAKE_EN; + + time = (u64)readl(rtcdev->base + ALARM_LOWER_REG) << 32; + time |= (readl(rtcdev->base + ALARM_UPPER_REG) & ALARM_UPPER_MASK); + rtc_time64_to_tm(time, &alrm->time); + + return 0; +} + +static int mpfs_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) +{ + struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev); + u32 mode, ctrl; + u64 time; + + /* Disable the alarm before updating */ + ctrl = readl(rtcdev->base + CONTROL_REG); + ctrl |= CONTROL_ALARM_OFF_BIT; + writel(ctrl, rtcdev->base + CONTROL_REG); + + time = rtc_tm_to_time64(&alrm->time); + + writel((u32)time, rtcdev->base + ALARM_LOWER_REG); + writel((u32)(time >> 32) & ALARM_UPPER_MASK, rtcdev->base + ALARM_UPPER_REG); + + /* Bypass compare register in alarm mode */ + writel(GENMASK(31, 0), rtcdev->base + COMPARE_LOWER_REG); + writel(GENMASK(29, 0), rtcdev->base + COMPARE_UPPER_REG); + + /* Configure the RTC to enable the alarm. */ + ctrl = readl(rtcdev->base + CONTROL_REG); + mode = readl(rtcdev->base + MODE_REG); + if (alrm->enabled) { + mode = MODE_WAKE_EN | MODE_WAKE_CONTINUE; + /* Enable the alarm */ + ctrl &= ~CONTROL_ALARM_OFF_BIT; + ctrl |= CONTROL_ALARM_ON_BIT; + } + ctrl &= ~CONTROL_STOP_BIT; + ctrl |= CONTROL_START_BIT; + writel(ctrl, rtcdev->base + CONTROL_REG); + writel(mode, rtcdev->base + MODE_REG); + + return 0; +} + +static int mpfs_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) +{ + struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev); + u32 ctrl; + + ctrl = readl(rtcdev->base + CONTROL_REG); + ctrl &= ~(CONTROL_ALARM_ON_BIT | CONTROL_ALARM_OFF_BIT | CONTROL_STOP_BIT); + + if (enabled) + ctrl |= CONTROL_ALARM_ON_BIT; + else + ctrl |= CONTROL_ALARM_OFF_BIT; + + writel(ctrl, rtcdev->base + CONTROL_REG); + + return 0; +} + +static irqreturn_t mpfs_rtc_wakeup_irq_handler(int irq, void *dev) +{ + struct mpfs_rtc_dev *rtcdev = dev; + + mpfs_rtc_clear_irq(rtcdev); + + rtc_update_irq(rtcdev->rtc, 1, RTC_IRQF | RTC_AF); + + return IRQ_HANDLED; +} + +static const struct rtc_class_ops mpfs_rtc_ops = { + .read_time = mpfs_rtc_readtime, + .set_time = mpfs_rtc_settime, + .read_alarm = mpfs_rtc_readalarm, + .set_alarm = mpfs_rtc_setalarm, + .alarm_irq_enable = mpfs_rtc_alarm_irq_enable, +}; + +static int mpfs_rtc_probe(struct platform_device *pdev) +{ + struct mpfs_rtc_dev *rtcdev; + struct clk *clk; + unsigned long prescaler; + int wakeup_irq, ret; + + rtcdev = devm_kzalloc(&pdev->dev, sizeof(struct mpfs_rtc_dev), GFP_KERNEL); + if (!rtcdev) + return -ENOMEM; + + platform_set_drvdata(pdev, rtcdev); + + rtcdev->rtc = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(rtcdev->rtc)) + return PTR_ERR(rtcdev->rtc); + + rtcdev->rtc->ops = &mpfs_rtc_ops; + + /* range is capped by alarm max, lower reg is 31:0 & upper is 10:0 */ + rtcdev->rtc->range_max = GENMASK_ULL(42, 0); + + clk = devm_clk_get_enabled(&pdev->dev, "rtc"); + if (IS_ERR(clk)) + return PTR_ERR(clk); + + rtcdev->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(rtcdev->base)) { + dev_dbg(&pdev->dev, "invalid ioremap resources\n"); + return PTR_ERR(rtcdev->base); + } + + wakeup_irq = platform_get_irq(pdev, 0); + if (wakeup_irq <= 0) { + dev_dbg(&pdev->dev, "could not get wakeup irq\n"); + return wakeup_irq; + } + ret = devm_request_irq(&pdev->dev, wakeup_irq, mpfs_rtc_wakeup_irq_handler, 0, + dev_name(&pdev->dev), rtcdev); + if (ret) { + dev_dbg(&pdev->dev, "could not request wakeup irq\n"); + return ret; + } + + /* prescaler hardware adds 1 to reg value */ + prescaler = clk_get_rate(devm_clk_get(&pdev->dev, "rtcref")) - 1; + if (prescaler > MAX_PRESCALER_COUNT) { + dev_dbg(&pdev->dev, "invalid prescaler %lu\n", prescaler); + return -EINVAL; + } + + writel(prescaler, rtcdev->base + PRESCALER_REG); + dev_info(&pdev->dev, "prescaler set to: %lu\n", prescaler); + + devm_device_init_wakeup(&pdev->dev); + ret = devm_pm_set_wake_irq(&pdev->dev, wakeup_irq); + if (ret) + dev_err(&pdev->dev, "failed to enable irq wake\n"); + + return devm_rtc_register_device(rtcdev->rtc); +} + +static const struct of_device_id mpfs_rtc_of_match[] = { + { .compatible = "microchip,mpfs-rtc" }, + { } +}; + +MODULE_DEVICE_TABLE(of, mpfs_rtc_of_match); + +static struct platform_driver mpfs_rtc_driver = { + .probe = mpfs_rtc_probe, + .driver = { + .name = "mpfs_rtc", + .of_match_table = mpfs_rtc_of_match, + }, +}; + +module_platform_driver(mpfs_rtc_driver); + +MODULE_DESCRIPTION("Real time clock for Microchip Polarfire SoC"); +MODULE_AUTHOR("Daire McNamara "); +MODULE_AUTHOR("Conor Dooley "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1