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-ssd202d.c | 248 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 248 insertions(+) create mode 100644 drivers/rtc/rtc-ssd202d.c (limited to 'drivers/rtc/rtc-ssd202d.c') diff --git a/drivers/rtc/rtc-ssd202d.c b/drivers/rtc/rtc-ssd202d.c new file mode 100644 index 000000000..72aa02eb8 --- /dev/null +++ b/drivers/rtc/rtc-ssd202d.c @@ -0,0 +1,248 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Real time clocks driver for MStar/SigmaStar SSD202D SoCs. + * + * (C) 2021 Daniel Palmer + * (C) 2023 Romain Perier + */ + +#include +#include +#include +#include +#include +#include +#include + +#define REG_CTRL 0x0 +#define REG_CTRL1 0x4 +#define REG_ISO_CTRL 0xc +#define REG_WRDATA_L 0x10 +#define REG_WRDATA_H 0x14 +#define REG_ISOACK 0x20 +#define REG_RDDATA_L 0x24 +#define REG_RDDATA_H 0x28 +#define REG_RDCNT_L 0x30 +#define REG_RDCNT_H 0x34 +#define REG_CNT_TRIG 0x38 +#define REG_PWRCTRL 0x3c +#define REG_RTC_TEST 0x54 + +#define CNT_RD_TRIG_BIT BIT(0) +#define CNT_RD_BIT BIT(0) +#define BASE_WR_BIT BIT(1) +#define BASE_RD_BIT BIT(2) +#define CNT_RST_BIT BIT(3) +#define ISO_CTRL_ACK_MASK BIT(3) +#define ISO_CTRL_ACK_SHIFT 3 +#define SW0_WR_BIT BIT(5) +#define SW1_WR_BIT BIT(6) +#define SW0_RD_BIT BIT(7) +#define SW1_RD_BIT BIT(8) + +#define ISO_CTRL_MASK GENMASK(2, 0) + +struct ssd202d_rtc { + struct rtc_device *rtc_dev; + void __iomem *base; +}; + +static u8 read_iso_en(void __iomem *base) +{ + return readb(base + REG_RTC_TEST) & 0x1; +} + +static u8 read_iso_ctrl_ack(void __iomem *base) +{ + return (readb(base + REG_ISOACK) & ISO_CTRL_ACK_MASK) >> ISO_CTRL_ACK_SHIFT; +} + +static int ssd202d_rtc_isoctrl(struct ssd202d_rtc *priv) +{ + static const unsigned int sequence[] = { 0x0, 0x1, 0x3, 0x7, 0x5, 0x1, 0x0 }; + unsigned int val; + struct device *dev = &priv->rtc_dev->dev; + int i, ret; + + /* + * This gates iso_en by writing a special sequence of bytes to iso_ctrl + * and ensuring that it has been correctly applied by reading iso_ctrl_ack + */ + for (i = 0; i < ARRAY_SIZE(sequence); i++) { + writeb(sequence[i] & ISO_CTRL_MASK, priv->base + REG_ISO_CTRL); + + ret = read_poll_timeout(read_iso_ctrl_ack, val, val == (i % 2), 100, + 20 * 100, true, priv->base); + if (ret) { + dev_dbg(dev, "Timeout waiting for ack byte %i (%x) of sequence\n", i, + sequence[i]); + return ret; + } + } + + /* + * At this point iso_en should be raised for 1ms + */ + ret = read_poll_timeout(read_iso_en, val, val, 100, 22 * 100, true, priv->base); + if (ret) + dev_dbg(dev, "Timeout waiting for iso_en\n"); + mdelay(2); + return 0; +} + +static void ssd202d_rtc_read_reg(struct ssd202d_rtc *priv, unsigned int reg, + unsigned int field, unsigned int *base) +{ + unsigned int l, h; + u16 val; + + /* Ask for the content of an RTC value into RDDATA by gating iso_en, + * then iso_en is gated and the content of RDDATA can be read + */ + val = readw(priv->base + reg); + writew(val | field, priv->base + reg); + ssd202d_rtc_isoctrl(priv); + writew(val & ~field, priv->base + reg); + + l = readw(priv->base + REG_RDDATA_L); + h = readw(priv->base + REG_RDDATA_H); + + *base = (h << 16) | l; +} + +static void ssd202d_rtc_write_reg(struct ssd202d_rtc *priv, unsigned int reg, + unsigned int field, u32 base) +{ + u16 val; + + /* Set the content of an RTC value from WRDATA by gating iso_en */ + val = readw(priv->base + reg); + writew(val | field, priv->base + reg); + writew(base, priv->base + REG_WRDATA_L); + writew(base >> 16, priv->base + REG_WRDATA_H); + ssd202d_rtc_isoctrl(priv); + writew(val & ~field, priv->base + reg); +} + +static int ssd202d_rtc_read_counter(struct ssd202d_rtc *priv, unsigned int *counter) +{ + unsigned int l, h; + u16 val; + + val = readw(priv->base + REG_CTRL1); + writew(val | CNT_RD_BIT, priv->base + REG_CTRL1); + ssd202d_rtc_isoctrl(priv); + writew(val & ~CNT_RD_BIT, priv->base + REG_CTRL1); + + val = readw(priv->base + REG_CTRL1); + writew(val | CNT_RD_TRIG_BIT, priv->base + REG_CNT_TRIG); + writew(val & ~CNT_RD_TRIG_BIT, priv->base + REG_CNT_TRIG); + + l = readw(priv->base + REG_RDCNT_L); + h = readw(priv->base + REG_RDCNT_H); + + *counter = (h << 16) | l; + + return 0; +} + +static int ssd202d_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct ssd202d_rtc *priv = dev_get_drvdata(dev); + unsigned int sw0, base, counter; + u32 seconds; + int ret; + + /* Check that RTC is enabled by SW */ + ssd202d_rtc_read_reg(priv, REG_CTRL, SW0_RD_BIT, &sw0); + if (sw0 != 1) + return -EINVAL; + + /* Get RTC base value from RDDATA */ + ssd202d_rtc_read_reg(priv, REG_CTRL, BASE_RD_BIT, &base); + /* Get RTC counter value from RDDATA */ + ret = ssd202d_rtc_read_counter(priv, &counter); + if (ret) + return ret; + + seconds = base + counter; + + rtc_time64_to_tm(seconds, tm); + + return 0; +} + +static int ssd202d_rtc_reset_counter(struct ssd202d_rtc *priv) +{ + u16 val; + + val = readw(priv->base + REG_CTRL); + writew(val | CNT_RST_BIT, priv->base + REG_CTRL); + ssd202d_rtc_isoctrl(priv); + writew(val & ~CNT_RST_BIT, priv->base + REG_CTRL); + ssd202d_rtc_isoctrl(priv); + + return 0; +} + +static int ssd202d_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct ssd202d_rtc *priv = dev_get_drvdata(dev); + unsigned long seconds = rtc_tm_to_time64(tm); + + ssd202d_rtc_write_reg(priv, REG_CTRL, BASE_WR_BIT, seconds); + ssd202d_rtc_reset_counter(priv); + ssd202d_rtc_write_reg(priv, REG_CTRL, SW0_WR_BIT, 1); + + return 0; +} + +static const struct rtc_class_ops ssd202d_rtc_ops = { + .read_time = ssd202d_rtc_read_time, + .set_time = ssd202d_rtc_set_time, +}; + +static int ssd202d_rtc_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct ssd202d_rtc *priv; + + priv = devm_kzalloc(&pdev->dev, sizeof(struct ssd202d_rtc), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + priv->rtc_dev = devm_rtc_allocate_device(dev); + if (IS_ERR(priv->rtc_dev)) + return PTR_ERR(priv->rtc_dev); + + priv->rtc_dev->ops = &ssd202d_rtc_ops; + priv->rtc_dev->range_max = U32_MAX; + + platform_set_drvdata(pdev, priv); + + return devm_rtc_register_device(priv->rtc_dev); +} + +static const struct of_device_id ssd202d_rtc_of_match_table[] = { + { .compatible = "mstar,ssd202d-rtc" }, + { } +}; +MODULE_DEVICE_TABLE(of, ssd202d_rtc_of_match_table); + +static struct platform_driver ssd202d_rtc_driver = { + .probe = ssd202d_rtc_probe, + .driver = { + .name = "ssd202d-rtc", + .of_match_table = ssd202d_rtc_of_match_table, + }, +}; +module_platform_driver(ssd202d_rtc_driver); + +MODULE_AUTHOR("Daniel Palmer "); +MODULE_AUTHOR("Romain Perier "); +MODULE_DESCRIPTION("MStar SSD202D RTC Driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1