1 files changed, 96 insertions, 0 deletions

diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
new file mode 100644
index 000000000000..3794715b2972
--- /dev/null
+++ b/arch/powerpc/lib/locks.c
@@ -0,0 +1,96 @@
+/*
+ * Spin and read/write lock operations.
+ *
+ * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
+ * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
+ *   Rework to support virtual processors
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/stringify.h>
+#include <linux/smp.h>
+
+/* waiting for a spinlock... */
+#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
+#include <asm/hvcall.h>
+#include <asm/iSeries/HvCall.h>
+
+void __spin_yield(raw_spinlock_t *lock)
+{
+        unsigned int lock_value, holder_cpu, yield_count;
+        struct paca_struct *holder_paca;
+
+        lock_value = lock->slock;
+        if (lock_value == 0)
+                return;
+        holder_cpu = lock_value & 0xffff;
+        BUG_ON(holder_cpu >= NR_CPUS);
+        holder_paca = &paca[holder_cpu];
+        yield_count = holder_paca->lppaca.yield_count;
+        if ((yield_count & 1) == 0)
+                return;         /* virtual cpu is currently running */
+        rmb();
+        if (lock->slock != lock_value)
+                return;         /* something has changed */
+#ifdef CONFIG_PPC_ISERIES
+        HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
+                ((u64)holder_cpu << 32) | yield_count);
+#else
+        plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
+                           yield_count);
+#endif
+}
+
+/*
+ * Waiting for a read lock or a write lock on a rwlock...
+ * This turns out to be the same for read and write locks, since
+ * we only know the holder if it is write-locked.
+ */
+void __rw_yield(raw_rwlock_t *rw)
+{
+        int lock_value;
+        unsigned int holder_cpu, yield_count;
+        struct paca_struct *holder_paca;
+
+        lock_value = rw->lock;
+        if (lock_value >= 0)
+                return;         /* no write lock at present */
+        holder_cpu = lock_value & 0xffff;
+        BUG_ON(holder_cpu >= NR_CPUS);
+        holder_paca = &paca[holder_cpu];
+        yield_count = holder_paca->lppaca.yield_count;
+        if ((yield_count & 1) == 0)
+                return;         /* virtual cpu is currently running */
+        rmb();
+        if (rw->lock != lock_value)
+                return;         /* something has changed */
+#ifdef CONFIG_PPC_ISERIES
+        HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
+                ((u64)holder_cpu << 32) | yield_count);
+#else
+        plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
+                           yield_count);
+#endif
+}
+#endif
+
+void __raw_spin_unlock_wait(raw_spinlock_t *lock)
+{
+        while (lock->slock) {
+                HMT_low();
+                if (SHARED_PROCESSOR)
+                        __spin_yield(lock);
+        }
+        HMT_medium();
+}
+
+EXPORT_SYMBOL(__raw_spin_unlock_wait);