asm-generic: add generic versions of common headers
These are all kernel internal interfaces that get copied
around a lot. In most cases, architectures can provide
their own optimized versions, but these generic versions
can work as well.
I have tried to use the most common contents of each
header to allow existing architectures to migrate easily.
Thanks to Remis for suggesting a number of cleanups.
Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/include/asm-generic/system.h b/include/asm-generic/system.h
new file mode 100644
index 0000000..efa403b
--- /dev/null
+++ b/include/asm-generic/system.h
@@ -0,0 +1,161 @@
+/* Generic system definitions, based on MN10300 definitions.
+ *
+ * It should be possible to use these on really simple architectures,
+ * but it serves more as a starting point for new ports.
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#ifndef __ASM_GENERIC_SYSTEM_H
+#define __ASM_GENERIC_SYSTEM_H
+
+#ifdef __KERNEL__
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/irqflags.h>
+
+#include <asm/cmpxchg-local.h>
+
+struct task_struct;
+
+/* context switching is now performed out-of-line in switch_to.S */
+extern struct task_struct *__switch_to(struct task_struct *,
+ struct task_struct *);
+#define switch_to(prev, next, last) \
+ do { \
+ ((last) = __switch_to((prev), (next))); \
+ } while (0)
+
+#define arch_align_stack(x) (x)
+
+#define nop() asm volatile ("nop")
+
+#endif /* !__ASSEMBLY__ */
+
+/*
+ * Force strict CPU ordering.
+ * And yes, this is required on UP too when we're talking
+ * to devices.
+ *
+ * This implementation only contains a compiler barrier.
+ */
+
+#define mb() asm volatile ("": : :"memory")
+#define rmb() mb()
+#define wmb() asm volatile ("": : :"memory")
+
+#ifdef CONFIG_SMP
+#define smp_mb() mb()
+#define smp_rmb() rmb()
+#define smp_wmb() wmb()
+#else
+#define smp_mb() barrier()
+#define smp_rmb() barrier()
+#define smp_wmb() barrier()
+#endif
+
+#define set_mb(var, value) do { var = value; mb(); } while (0)
+#define set_wmb(var, value) do { var = value; wmb(); } while (0)
+
+#define read_barrier_depends() do {} while (0)
+#define smp_read_barrier_depends() do {} while (0)
+
+/*
+ * we make sure local_irq_enable() doesn't cause priority inversion
+ */
+#ifndef __ASSEMBLY__
+
+/* This function doesn't exist, so you'll get a linker error
+ * if something tries to do an invalid xchg(). */
+extern void __xchg_called_with_bad_pointer(void);
+
+static inline
+unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
+{
+ unsigned long ret, flags;
+
+ switch (size) {
+ case 1:
+#ifdef __xchg_u8
+ return __xchg_u8(x, ptr);
+#else
+ local_irq_save(flags);
+ ret = *(volatile u8 *)ptr;
+ *(volatile u8 *)ptr = x;
+ local_irq_restore(flags);
+ return ret;
+#endif /* __xchg_u8 */
+
+ case 2:
+#ifdef __xchg_u16
+ return __xchg_u16(x, ptr);
+#else
+ local_irq_save(flags);
+ ret = *(volatile u16 *)ptr;
+ *(volatile u16 *)ptr = x;
+ local_irq_restore(flags);
+ return ret;
+#endif /* __xchg_u16 */
+
+ case 4:
+#ifdef __xchg_u32
+ return __xchg_u32(x, ptr);
+#else
+ local_irq_save(flags);
+ ret = *(volatile u32 *)ptr;
+ *(volatile u32 *)ptr = x;
+ local_irq_restore(flags);
+ return ret;
+#endif /* __xchg_u32 */
+
+#ifdef CONFIG_64BIT
+ case 8:
+#ifdef __xchg_u64
+ return __xchg_u64(x, ptr);
+#else
+ local_irq_save(flags);
+ ret = *(volatile u64 *)ptr;
+ *(volatile u64 *)ptr = x;
+ local_irq_restore(flags);
+ return ret;
+#endif /* __xchg_u64 */
+#endif /* CONFIG_64BIT */
+
+ default:
+ __xchg_called_with_bad_pointer();
+ return x;
+ }
+}
+
+#define xchg(ptr, x) \
+ ((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
+
+static inline unsigned long __cmpxchg(volatile unsigned long *m,
+ unsigned long old, unsigned long new)
+{
+ unsigned long retval;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ retval = *m;
+ if (retval == old)
+ *m = new;
+ local_irq_restore(flags);
+ return retval;
+}
+
+#define cmpxchg(ptr, o, n) \
+ ((__typeof__(*(ptr))) __cmpxchg((unsigned long *)(ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n)))
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_GENERIC_SYSTEM_H */