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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /arch/hexagon/include/asm/cmpxchg.h
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/hexagon/include/asm/cmpxchg.h')
-rw-r--r--arch/hexagon/include/asm/cmpxchg.h75
1 files changed, 75 insertions, 0 deletions
diff --git a/arch/hexagon/include/asm/cmpxchg.h b/arch/hexagon/include/asm/cmpxchg.h
new file mode 100644
index 0000000000..bf6cf5579c
--- /dev/null
+++ b/arch/hexagon/include/asm/cmpxchg.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * xchg/cmpxchg operations for the Hexagon architecture
+ *
+ * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef _ASM_CMPXCHG_H
+#define _ASM_CMPXCHG_H
+
+/*
+ * __arch_xchg - atomically exchange a register and a memory location
+ * @x: value to swap
+ * @ptr: pointer to memory
+ * @size: size of the value
+ *
+ * Only 4 bytes supported currently.
+ *
+ * Note: there was an errata for V2 about .new's and memw_locked.
+ *
+ */
+static inline unsigned long
+__arch_xchg(unsigned long x, volatile void *ptr, int size)
+{
+ unsigned long retval;
+
+ /* Can't seem to use printk or panic here, so just stop */
+ if (size != 4) do { asm volatile("brkpt;\n"); } while (1);
+
+ __asm__ __volatile__ (
+ "1: %0 = memw_locked(%1);\n" /* load into retval */
+ " memw_locked(%1,P0) = %2;\n" /* store into memory */
+ " if (!P0) jump 1b;\n"
+ : "=&r" (retval)
+ : "r" (ptr), "r" (x)
+ : "memory", "p0"
+ );
+ return retval;
+}
+
+/*
+ * Atomically swap the contents of a register with memory. Should be atomic
+ * between multiple CPU's and within interrupts on the same CPU.
+ */
+#define arch_xchg(ptr, v) ((__typeof__(*(ptr)))__arch_xchg((unsigned long)(v), (ptr), \
+ sizeof(*(ptr))))
+
+/*
+ * see rt-mutex-design.txt; cmpxchg supposedly checks if *ptr == A and swaps.
+ * looks just like atomic_cmpxchg on our arch currently with a bunch of
+ * variable casting.
+ */
+
+#define arch_cmpxchg(ptr, old, new) \
+({ \
+ __typeof__(ptr) __ptr = (ptr); \
+ __typeof__(*(ptr)) __old = (old); \
+ __typeof__(*(ptr)) __new = (new); \
+ __typeof__(*(ptr)) __oldval = 0; \
+ \
+ asm volatile( \
+ "1: %0 = memw_locked(%1);\n" \
+ " { P0 = cmp.eq(%0,%2);\n" \
+ " if (!P0.new) jump:nt 2f; }\n" \
+ " memw_locked(%1,p0) = %3;\n" \
+ " if (!P0) jump 1b;\n" \
+ "2:\n" \
+ : "=&r" (__oldval) \
+ : "r" (__ptr), "r" (__old), "r" (__new) \
+ : "memory", "p0" \
+ ); \
+ __oldval; \
+})
+
+#endif /* _ASM_CMPXCHG_H */