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-rw-r--r--arch/arm/include/asm/system.h173
1 files changed, 173 insertions, 0 deletions
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index 7fce8f3b391..d65b2f5bf41 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -319,6 +319,12 @@ extern void enable_hlt(void);
#include <asm-generic/cmpxchg-local.h>
+#if __LINUX_ARM_ARCH__ < 6
+
+#ifdef CONFIG_SMP
+#error "SMP is not supported on this platform"
+#endif
+
/*
* cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
* them available.
@@ -332,6 +338,173 @@ extern void enable_hlt(void);
#include <asm-generic/cmpxchg.h>
#endif
+#else /* __LINUX_ARM_ARCH__ >= 6 */
+
+extern void __bad_cmpxchg(volatile void *ptr, int size);
+
+/*
+ * cmpxchg only support 32-bits operands on ARMv6.
+ */
+
+static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
+ unsigned long new, int size)
+{
+ unsigned long oldval, res;
+
+ switch (size) {
+#ifdef CONFIG_CPU_32v6K
+ case 1:
+ do {
+ asm volatile("@ __cmpxchg1\n"
+ " ldrexb %1, [%2]\n"
+ " mov %0, #0\n"
+ " teq %1, %3\n"
+ " strexbeq %0, %4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (ptr), "Ir" (old), "r" (new)
+ : "memory", "cc");
+ } while (res);
+ break;
+ case 2:
+ do {
+ asm volatile("@ __cmpxchg1\n"
+ " ldrexh %1, [%2]\n"
+ " mov %0, #0\n"
+ " teq %1, %3\n"
+ " strexheq %0, %4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (ptr), "Ir" (old), "r" (new)
+ : "memory", "cc");
+ } while (res);
+ break;
+#endif /* CONFIG_CPU_32v6K */
+ case 4:
+ do {
+ asm volatile("@ __cmpxchg4\n"
+ " ldrex %1, [%2]\n"
+ " mov %0, #0\n"
+ " teq %1, %3\n"
+ " strexeq %0, %4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (ptr), "Ir" (old), "r" (new)
+ : "memory", "cc");
+ } while (res);
+ break;
+ default:
+ __bad_cmpxchg(ptr, size);
+ oldval = 0;
+ }
+
+ return oldval;
+}
+
+static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
+ unsigned long new, int size)
+{
+ unsigned long ret;
+
+ smp_mb();
+ ret = __cmpxchg(ptr, old, new, size);
+ smp_mb();
+
+ return ret;
+}
+
+#define cmpxchg(ptr,o,n) \
+ ((__typeof__(*(ptr)))__cmpxchg_mb((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))))
+
+static inline unsigned long __cmpxchg_local(volatile void *ptr,
+ unsigned long old,
+ unsigned long new, int size)
+{
+ unsigned long ret;
+
+ switch (size) {
+#ifndef CONFIG_CPU_32v6K
+ case 1:
+ case 2:
+ ret = __cmpxchg_local_generic(ptr, old, new, size);
+ break;
+#endif /* !CONFIG_CPU_32v6K */
+ default:
+ ret = __cmpxchg(ptr, old, new, size);
+ }
+
+ return ret;
+}
+
+#define cmpxchg_local(ptr,o,n) \
+ ((__typeof__(*(ptr)))__cmpxchg_local((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))))
+
+#ifdef CONFIG_CPU_32v6K
+
+/*
+ * Note : ARMv7-M (currently unsupported by Linux) does not support
+ * ldrexd/strexd. If ARMv7-M is ever supported by the Linux kernel, it should
+ * not be allowed to use __cmpxchg64.
+ */
+static inline unsigned long long __cmpxchg64(volatile void *ptr,
+ unsigned long long old,
+ unsigned long long new)
+{
+ register unsigned long long oldval asm("r0");
+ register unsigned long long __old asm("r2") = old;
+ register unsigned long long __new asm("r4") = new;
+ unsigned long res;
+
+ do {
+ asm volatile(
+ " @ __cmpxchg8\n"
+ " ldrexd %1, %H1, [%2]\n"
+ " mov %0, #0\n"
+ " teq %1, %3\n"
+ " teqeq %H1, %H3\n"
+ " strexdeq %0, %4, %H4, [%2]\n"
+ : "=&r" (res), "=&r" (oldval)
+ : "r" (ptr), "Ir" (__old), "r" (__new)
+ : "memory", "cc");
+ } while (res);
+
+ return oldval;
+}
+
+static inline unsigned long long __cmpxchg64_mb(volatile void *ptr,
+ unsigned long long old,
+ unsigned long long new)
+{
+ unsigned long long ret;
+
+ smp_mb();
+ ret = __cmpxchg64(ptr, old, new);
+ smp_mb();
+
+ return ret;
+}
+
+#define cmpxchg64(ptr,o,n) \
+ ((__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \
+ (unsigned long long)(o), \
+ (unsigned long long)(n)))
+
+#define cmpxchg64_local(ptr,o,n) \
+ ((__typeof__(*(ptr)))__cmpxchg64((ptr), \
+ (unsigned long long)(o), \
+ (unsigned long long)(n)))
+
+#else /* !CONFIG_CPU_32v6K */
+
+#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
+
+#endif /* CONFIG_CPU_32v6K */
+
+#endif /* __LINUX_ARM_ARCH__ >= 6 */
+
#endif /* __ASSEMBLY__ */
#define arch_align_stack(x) (x)