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-rw-r--r--arch/loongarch/include/asm/cmpxchg.h219
1 files changed, 219 insertions, 0 deletions
diff --git a/arch/loongarch/include/asm/cmpxchg.h b/arch/loongarch/include/asm/cmpxchg.h
new file mode 100644
index 000000000..ecfa6cf79
--- /dev/null
+++ b/arch/loongarch/include/asm/cmpxchg.h
@@ -0,0 +1,219 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef __ASM_CMPXCHG_H
+#define __ASM_CMPXCHG_H
+
+#include <linux/bits.h>
+#include <linux/build_bug.h>
+#include <asm/barrier.h>
+
+#define __xchg_asm(amswap_db, m, val) \
+({ \
+ __typeof(val) __ret; \
+ \
+ __asm__ __volatile__ ( \
+ " "amswap_db" %1, %z2, %0 \n" \
+ : "+ZB" (*m), "=&r" (__ret) \
+ : "Jr" (val) \
+ : "memory"); \
+ \
+ __ret; \
+})
+
+static inline unsigned int __xchg_small(volatile void *ptr, unsigned int val,
+ unsigned int size)
+{
+ unsigned int shift;
+ u32 old32, mask, temp;
+ volatile u32 *ptr32;
+
+ /* Mask value to the correct size. */
+ mask = GENMASK((size * BITS_PER_BYTE) - 1, 0);
+ val &= mask;
+
+ /*
+ * Calculate a shift & mask that correspond to the value we wish to
+ * exchange within the naturally aligned 4 byte integerthat includes
+ * it.
+ */
+ shift = (unsigned long)ptr & 0x3;
+ shift *= BITS_PER_BYTE;
+ mask <<= shift;
+
+ /*
+ * Calculate a pointer to the naturally aligned 4 byte integer that
+ * includes our byte of interest, and load its value.
+ */
+ ptr32 = (volatile u32 *)((unsigned long)ptr & ~0x3);
+
+ asm volatile (
+ "1: ll.w %0, %3 \n"
+ " andn %1, %0, %z4 \n"
+ " or %1, %1, %z5 \n"
+ " sc.w %1, %2 \n"
+ " beqz %1, 1b \n"
+ : "=&r" (old32), "=&r" (temp), "=ZC" (*ptr32)
+ : "ZC" (*ptr32), "Jr" (mask), "Jr" (val << shift)
+ : "memory");
+
+ return (old32 & mask) >> shift;
+}
+
+static __always_inline unsigned long
+__xchg(volatile void *ptr, unsigned long x, int size)
+{
+ switch (size) {
+ case 1:
+ case 2:
+ return __xchg_small(ptr, x, size);
+
+ case 4:
+ return __xchg_asm("amswap_db.w", (volatile u32 *)ptr, (u32)x);
+
+ case 8:
+ return __xchg_asm("amswap_db.d", (volatile u64 *)ptr, (u64)x);
+
+ default:
+ BUILD_BUG();
+ }
+
+ return 0;
+}
+
+#define arch_xchg(ptr, x) \
+({ \
+ __typeof__(*(ptr)) __res; \
+ \
+ __res = (__typeof__(*(ptr))) \
+ __xchg((ptr), (unsigned long)(x), sizeof(*(ptr))); \
+ \
+ __res; \
+})
+
+#define __cmpxchg_asm(ld, st, m, old, new) \
+({ \
+ __typeof(old) __ret; \
+ \
+ __asm__ __volatile__( \
+ "1: " ld " %0, %2 # __cmpxchg_asm \n" \
+ " bne %0, %z3, 2f \n" \
+ " move $t0, %z4 \n" \
+ " " st " $t0, %1 \n" \
+ " beqz $t0, 1b \n" \
+ "2: \n" \
+ __WEAK_LLSC_MB \
+ : "=&r" (__ret), "=ZB"(*m) \
+ : "ZB"(*m), "Jr" (old), "Jr" (new) \
+ : "t0", "memory"); \
+ \
+ __ret; \
+})
+
+static inline unsigned int __cmpxchg_small(volatile void *ptr, unsigned int old,
+ unsigned int new, unsigned int size)
+{
+ unsigned int shift;
+ u32 old32, mask, temp;
+ volatile u32 *ptr32;
+
+ /* Mask inputs to the correct size. */
+ mask = GENMASK((size * BITS_PER_BYTE) - 1, 0);
+ old &= mask;
+ new &= mask;
+
+ /*
+ * Calculate a shift & mask that correspond to the value we wish to
+ * compare & exchange within the naturally aligned 4 byte integer
+ * that includes it.
+ */
+ shift = (unsigned long)ptr & 0x3;
+ shift *= BITS_PER_BYTE;
+ old <<= shift;
+ new <<= shift;
+ mask <<= shift;
+
+ /*
+ * Calculate a pointer to the naturally aligned 4 byte integer that
+ * includes our byte of interest, and load its value.
+ */
+ ptr32 = (volatile u32 *)((unsigned long)ptr & ~0x3);
+
+ asm volatile (
+ "1: ll.w %0, %3 \n"
+ " and %1, %0, %z4 \n"
+ " bne %1, %z5, 2f \n"
+ " andn %1, %0, %z4 \n"
+ " or %1, %1, %z6 \n"
+ " sc.w %1, %2 \n"
+ " beqz %1, 1b \n"
+ " b 3f \n"
+ "2: \n"
+ __WEAK_LLSC_MB
+ "3: \n"
+ : "=&r" (old32), "=&r" (temp), "=ZC" (*ptr32)
+ : "ZC" (*ptr32), "Jr" (mask), "Jr" (old), "Jr" (new)
+ : "memory");
+
+ return (old32 & mask) >> shift;
+}
+
+static __always_inline unsigned long
+__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, unsigned int size)
+{
+ switch (size) {
+ case 1:
+ case 2:
+ return __cmpxchg_small(ptr, old, new, size);
+
+ case 4:
+ return __cmpxchg_asm("ll.w", "sc.w", (volatile u32 *)ptr,
+ (u32)old, new);
+
+ case 8:
+ return __cmpxchg_asm("ll.d", "sc.d", (volatile u64 *)ptr,
+ (u64)old, new);
+
+ default:
+ BUILD_BUG();
+ }
+
+ return 0;
+}
+
+#define arch_cmpxchg_local(ptr, old, new) \
+ ((__typeof__(*(ptr))) \
+ __cmpxchg((ptr), \
+ (unsigned long)(__typeof__(*(ptr)))(old), \
+ (unsigned long)(__typeof__(*(ptr)))(new), \
+ sizeof(*(ptr))))
+
+#define arch_cmpxchg(ptr, old, new) \
+({ \
+ __typeof__(*(ptr)) __res; \
+ \
+ __res = arch_cmpxchg_local((ptr), (old), (new)); \
+ \
+ __res; \
+})
+
+#ifdef CONFIG_64BIT
+#define arch_cmpxchg64_local(ptr, o, n) \
+ ({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ arch_cmpxchg_local((ptr), (o), (n)); \
+ })
+
+#define arch_cmpxchg64(ptr, o, n) \
+ ({ \
+ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
+ arch_cmpxchg((ptr), (o), (n)); \
+ })
+#else
+#include <asm-generic/cmpxchg-local.h>
+#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
+#define arch_cmpxchg64(ptr, o, n) arch_cmpxchg64_local((ptr), (o), (n))
+#endif
+
+#endif /* __ASM_CMPXCHG_H */