powerpc: Split ICSWX ACOP and PID processing

Some processors, like embedded, that already have a PID register that
is managed by the system.  This patch separates the ACOP and PID
processing into separate files so that the ACOP code can be shared.

Signed-off-by: Jimi Xenidis <jimix@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/mm/icswx_pid.c

@@ -0,0 +1,87 @@
+/*
+ *  ICSWX and ACOP/PID Management
+ *
+ *  Copyright (C) 2011 Anton Blanchard, IBM Corp. <anton@samba.org>
+ *
+ *  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/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/spinlock.h>
+#include <linux/idr.h>
+#include <linux/module.h>
+#include "icswx.h"
+
+#define COP_PID_MIN (COP_PID_NONE + 1)
+#define COP_PID_MAX (0xFFFF)
+
+static DEFINE_SPINLOCK(mmu_context_acop_lock);
+static DEFINE_IDA(cop_ida);
+
+static int new_cop_pid(struct ida *ida, int min_id, int max_id,
+		       spinlock_t *lock)
+{
+	int index;
+	int err;
+
+again:
+	if (!ida_pre_get(ida, GFP_KERNEL))
+		return -ENOMEM;
+
+	spin_lock(lock);
+	err = ida_get_new_above(ida, min_id, &index);
+	spin_unlock(lock);
+
+	if (err == -EAGAIN)
+		goto again;
+	else if (err)
+		return err;
+
+	if (index > max_id) {
+		spin_lock(lock);
+		ida_remove(ida, index);
+		spin_unlock(lock);
+		return -ENOMEM;
+	}
+
+	return index;
+}
+
+int get_cop_pid(struct mm_struct *mm)
+{
+	int pid;
+
+	if (mm->context.cop_pid == COP_PID_NONE) {
+		pid = new_cop_pid(&cop_ida, COP_PID_MIN, COP_PID_MAX,
+				  &mmu_context_acop_lock);
+		if (pid >= 0)
+			mm->context.cop_pid = pid;
+	}
+	return mm->context.cop_pid;
+}
+
+int disable_cop_pid(struct mm_struct *mm)
+{
+	int free_pid = COP_PID_NONE;
+
+	if ((!mm->context.acop) && (mm->context.cop_pid != COP_PID_NONE)) {
+		free_pid = mm->context.cop_pid;
+		mm->context.cop_pid = COP_PID_NONE;
+	}
+	return free_pid;
+}
+
+void free_cop_pid(int free_pid)
+{
+	spin_lock(&mmu_context_acop_lock);
+	ida_remove(&cop_ida, free_pid);
+	spin_unlock(&mmu_context_acop_lock);
+}