From 7fc4533b321fbe7ef6ce0ef05e3b99cebe13a39e Mon Sep 17 00:00:00 2001
From: "kaf24@firebug.cl.cam.ac.uk" <kaf24@firebug.cl.cam.ac.uk>
Date: Thu, 8 Dec 2005 15:24:02 +0100
Subject: Merge in the newer Xenbus implementation from Linux to the Mini-OS.
 The new version compiles and starts up, but I'm not really sure how to test
 the new xenbus implementation.

* Added unbind_evtchn
* Copied parts of the Linux spinlock implementation to make the changes to
  xenbus compared to Linux smaller. Also added a dummy rwsem implementation.
* Updated the xenbus-files

Signed-off-by: Simon Kagstrom <simon.kagstrom@bth.se>
---
 extras/mini-os/include/spinlock.h | 121 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 extras/mini-os/include/spinlock.h

(limited to 'extras/mini-os/include/spinlock.h')

diff --git a/extras/mini-os/include/spinlock.h b/extras/mini-os/include/spinlock.h
new file mode 100644
index 0000000000..4274cd2869
--- /dev/null
+++ b/extras/mini-os/include/spinlock.h
@@ -0,0 +1,121 @@
+#ifndef __ASM_SPINLOCK_H
+#define __ASM_SPINLOCK_H
+
+#include <lib.h>
+
+/*
+ * Your basic SMP spinlocks, allowing only a single CPU anywhere
+ */
+
+typedef struct {
+	volatile unsigned int slock;
+} spinlock_t;
+
+#define SPINLOCK_MAGIC	0xdead4ead
+
+#define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 }
+
+#define spin_lock_init(x)	do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
+
+/*
+ * Simple spin lock operations.  There are two variants, one clears IRQ's
+ * on the local processor, one does not.
+ *
+ * We make no fairness assumptions. They have a cost.
+ */
+
+#define spin_is_locked(x)	(*(volatile signed char *)(&(x)->slock) <= 0)
+#define spin_unlock_wait(x)	do { barrier(); } while(spin_is_locked(x))
+
+#define spin_lock_string \
+        "1:\n" \
+	LOCK \
+	"decb %0\n\t" \
+	"jns 3f\n" \
+	"2:\t" \
+	"rep;nop\n\t" \
+	"cmpb $0,%0\n\t" \
+	"jle 2b\n\t" \
+	"jmp 1b\n" \
+	"3:\n\t"
+
+#define spin_lock_string_flags \
+        "1:\n" \
+	LOCK \
+	"decb %0\n\t" \
+	"jns 4f\n\t" \
+	"2:\t" \
+	"testl $0x200, %1\n\t" \
+	"jz 3f\n\t" \
+	"#sti\n\t" \
+	"3:\t" \
+	"rep;nop\n\t" \
+	"cmpb $0, %0\n\t" \
+	"jle 3b\n\t" \
+	"#cli\n\t" \
+	"jmp 1b\n" \
+	"4:\n\t"
+
+/*
+ * This works. Despite all the confusion.
+ * (except on PPro SMP or if we are using OOSTORE)
+ * (PPro errata 66, 92)
+ */
+
+#define spin_unlock_string \
+	"xchgb %b0, %1" \
+		:"=q" (oldval), "=m" (lock->slock) \
+		:"0" (oldval) : "memory"
+
+static inline void _raw_spin_unlock(spinlock_t *lock)
+{
+	char oldval = 1;
+	__asm__ __volatile__(
+		spin_unlock_string
+	);
+}
+
+static inline int _raw_spin_trylock(spinlock_t *lock)
+{
+	char oldval;
+	__asm__ __volatile__(
+		"xchgb %b0,%1\n"
+		:"=q" (oldval), "=m" (lock->slock)
+		:"0" (0) : "memory");
+	return oldval > 0;
+}
+
+static inline void _raw_spin_lock(spinlock_t *lock)
+{
+	__asm__ __volatile__(
+		spin_lock_string
+		:"=m" (lock->slock) : : "memory");
+}
+
+static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
+{
+	__asm__ __volatile__(
+		spin_lock_string_flags
+		:"=m" (lock->slock) : "r" (flags) : "memory");
+}
+
+#define _spin_trylock(lock)     ({_raw_spin_trylock(lock) ? \
+                                1 : ({ 0;});})
+
+#define _spin_lock(lock)        \
+do {                            \
+        _raw_spin_lock(lock);   \
+} while(0)
+
+#define _spin_unlock(lock)      \
+do {                            \
+        _raw_spin_unlock(lock); \
+} while (0)
+
+
+#define spin_lock(lock)       _spin_lock(lock)
+#define spin_unlock(lock)       _spin_unlock(lock)
+
+#define DEFINE_SPINLOCK(x) spinlock_t x = SPIN_LOCK_UNLOCKED
+
+#endif
-- 
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