powerpc: Merge enough to start building in arch/powerpc.

This creates the directory structure under arch/powerpc and a bunch
of Kconfig files.  It does a first-cut merge of arch/powerpc/mm,
arch/powerpc/lib and arch/powerpc/platforms/powermac.  This is enough
to build a 32-bit powermac kernel with ARCH=powerpc.

For now we are getting some unmerged files from arch/ppc/kernel and
arch/ppc/syslib, or arch/ppc64/kernel.  This makes some minor changes
to files in those directories and files outside arch/powerpc.

The boot directory is still not merged.  That's going to be interesting.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 86 insertions, 0 deletions

diff --git a/arch/powerpc/mm/mmu_context.c b/arch/powerpc/mm/mmu_context.c
new file mode 100644
index 000000000000..a8816e0f6a86
--- /dev/null
+++ b/arch/powerpc/mm/mmu_context.c
@@ -0,0 +1,86 @@
+/*
+ * This file contains the routines for handling the MMU on those
+ * PowerPC implementations where the MMU substantially follows the
+ * architecture specification.  This includes the 6xx, 7xx, 7xxx,
+ * 8260, and POWER3 implementations but excludes the 8xx and 4xx.
+ *  -- paulus
+ *
+ *  Derived from arch/ppc/mm/init.c:
+ *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
+ *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
+ *    Copyright (C) 1996 Paul Mackerras
+ *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
+ *
+ *  Derived from "arch/i386/mm/init.c"
+ *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *
+ *  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/mm.h>
+#include <linux/init.h>
+
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+
+mm_context_t next_mmu_context;
+unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
+#ifdef FEW_CONTEXTS
+atomic_t nr_free_contexts;
+struct mm_struct *context_mm[LAST_CONTEXT+1];
+void steal_context(void);
+#endif /* FEW_CONTEXTS */
+
+/*
+ * Initialize the context management stuff.
+ */
+void __init
+mmu_context_init(void)
+{
+        /*
+         * Some processors have too few contexts to reserve one for
+         * init_mm, and require using context 0 for a normal task.
+         * Other processors reserve the use of context zero for the kernel.
+         * This code assumes FIRST_CONTEXT < 32.
+         */
+        context_map[0] = (1 << FIRST_CONTEXT) - 1;
+        next_mmu_context = FIRST_CONTEXT;
+#ifdef FEW_CONTEXTS
+        atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
+#endif /* FEW_CONTEXTS */
+}
+
+#ifdef FEW_CONTEXTS
+/*
+ * Steal a context from a task that has one at the moment.
+ * This is only used on 8xx and 4xx and we presently assume that
+ * they don't do SMP.  If they do then this will have to check
+ * whether the MM we steal is in use.
+ * We also assume that this is only used on systems that don't
+ * use an MMU hash table - this is true for 8xx and 4xx.
+ * This isn't an LRU system, it just frees up each context in
+ * turn (sort-of pseudo-random replacement :).  This would be the
+ * place to implement an LRU scheme if anyone was motivated to do it.
+ *  -- paulus
+ */
+void
+steal_context(void)
+{
+        struct mm_struct *mm;
+
+        /* free up context `next_mmu_context' */
+        /* if we shouldn't free context 0, don't... */
+        if (next_mmu_context < FIRST_CONTEXT)
+                next_mmu_context = FIRST_CONTEXT;
+        mm = context_mm[next_mmu_context];
+        flush_tlb_mm(mm);
+        destroy_context(mm);
+}
+#endif /* FEW_CONTEXTS */