kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

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 <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 56 insertions, 0 deletions

diff --git a/include/sound/wm2200.h b/include/sound/wm2200.h
new file mode 100644
index 000000000..2e4913ee2
--- /dev/null
+++ b/include/sound/wm2200.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * linux/sound/wm2200.h -- Platform data for WM2200
+ *
+ * Copyright 2012 Wolfson Microelectronics. PLC.
+ */
+
+#ifndef __LINUX_SND_WM2200_H
+#define __LINUX_SND_WM2200_H
+
+#define WM2200_GPIO_SET 0x10000
+#define WM2200_MAX_MICBIAS 2
+
+enum wm2200_in_mode {
+	WM2200_IN_SE = 0,
+	WM2200_IN_DIFF = 1,
+	WM2200_IN_DMIC = 2,
+};
+
+enum wm2200_dmic_sup {
+	WM2200_DMIC_SUP_MICVDD = 0,
+	WM2200_DMIC_SUP_MICBIAS1 = 1,
+	WM2200_DMIC_SUP_MICBIAS2 = 2,
+};
+
+enum wm2200_mbias_lvl {
+	WM2200_MBIAS_LVL_1V5 = 1,
+	WM2200_MBIAS_LVL_1V8 = 2,
+	WM2200_MBIAS_LVL_1V9 = 3,
+	WM2200_MBIAS_LVL_2V0 = 4,
+	WM2200_MBIAS_LVL_2V2 = 5,
+	WM2200_MBIAS_LVL_2V4 = 6,
+	WM2200_MBIAS_LVL_2V5 = 7,
+	WM2200_MBIAS_LVL_2V6 = 8,
+};
+
+struct wm2200_micbias {
+	enum wm2200_mbias_lvl mb_lvl;      /** Regulated voltage */
+	unsigned int discharge:1;          /** Actively discharge */
+	unsigned int fast_start:1;         /** Enable aggressive startup ramp rate */
+	unsigned int bypass:1;             /** Use bypass mode */
+};
+
+struct wm2200_pdata {
+	int irq_flags;
+
+	int gpio_defaults[4];
+
+	enum wm2200_in_mode in_mode[3];
+	enum wm2200_dmic_sup dmic_sup[3];
+
+	/** MICBIAS configurations */
+	struct wm2200_micbias micbias[WM2200_MAX_MICBIAS];
+};
+
+#endif