powerpc/mm: Split the various pgtable-* headers based on MMU type

This patch moves the definition of the PTE format for each MMU type
to separate files instead of all in one file. This improves overall
maintainability and will make it easier to add new types.

On 64-bit, additionally, I've separated the headers relative to the
format of the page table tree (3 vs. 4 levels for 64K vs 4K pages)
from the headers specific to the PTE format for hash based processors,
this will make it easier to add support for Book3 "E" 64-bit
implementations.

There are still some type-related ifdef's in the generic headers,
we might remove them in the long run, but this patch shouldn't result
in any code change, -hopefully- just definitions being moved around.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 102 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/pte-44x.h b/arch/powerpc/include/asm/pte-44x.h
new file mode 100644
index 00000000000..37e98bcf83e
--- /dev/null
+++ b/arch/powerpc/include/asm/pte-44x.h
@@ -0,0 +1,102 @@
+#ifndef _ASM_POWERPC_PTE_44x_H
+#define _ASM_POWERPC_PTE_44x_H
+#ifdef __KERNEL__
+
+/*
+ * Definitions for PPC440
+ *
+ * Because of the 3 word TLB entries to support 36-bit addressing,
+ * the attribute are difficult to map in such a fashion that they
+ * are easily loaded during exception processing.  I decided to
+ * organize the entry so the ERPN is the only portion in the
+ * upper word of the PTE and the attribute bits below are packed
+ * in as sensibly as they can be in the area below a 4KB page size
+ * oriented RPN.  This at least makes it easy to load the RPN and
+ * ERPN fields in the TLB. -Matt
+ *
+ * This isn't entirely true anymore, at least some bits are now
+ * easier to move into the TLB from the PTE. -BenH.
+ *
+ * Note that these bits preclude future use of a page size
+ * less than 4KB.
+ *
+ *
+ * PPC 440 core has following TLB attribute fields;
+ *
+ *   TLB1:
+ *   0  1  2  3  4  ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
+ *   RPN.................................  -  -  -  -  -  - ERPN.......
+ *
+ *   TLB2:
+ *   0  1  2  3  4  ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
+ *   -  -  -  -  -    - U0 U1 U2 U3 W  I  M  G  E   - UX UW UR SX SW SR
+ *
+ * Newer 440 cores (440x6 as used on AMCC 460EX/460GT) have additional
+ * TLB2 storage attibute fields. Those are:
+ *
+ *   TLB2:
+ *   0...10    11   12   13   14   15   16...31
+ *   no change WL1  IL1I IL1D IL2I IL2D no change
+ *
+ * There are some constrains and options, to decide mapping software bits
+ * into TLB entry.
+ *
+ *   - PRESENT *must* be in the bottom three bits because swap cache
+ *     entries use the top 29 bits for TLB2.
+ *
+ *   - FILE *must* be in the bottom three bits because swap cache
+ *     entries use the top 29 bits for TLB2.
+ *
+ *   - CACHE COHERENT bit (M) has no effect on original PPC440 cores,
+ *     because it doesn't support SMP. However, some later 460 variants
+ *     have -some- form of SMP support and so I keep the bit there for
+ *     future use
+ *
+ * With the PPC 44x Linux implementation, the 0-11th LSBs of the PTE are used
+ * for memory protection related functions (see PTE structure in
+ * include/asm-ppc/mmu.h).  The _PAGE_XXX definitions in this file map to the
+ * above bits.  Note that the bit values are CPU specific, not architecture
+ * specific.
+ *
+ * The kernel PTE entry holds an arch-dependent swp_entry structure under
+ * certain situations. In other words, in such situations some portion of
+ * the PTE bits are used as a swp_entry. In the PPC implementation, the
+ * 3-24th LSB are shared with swp_entry, however the 0-2nd three LSB still
+ * hold protection values. That means the three protection bits are
+ * reserved for both PTE and SWAP entry at the most significant three
+ * LSBs.
+ *
+ * There are three protection bits available for SWAP entry:
+ *	_PAGE_PRESENT
+ *	_PAGE_FILE
+ *	_PAGE_HASHPTE (if HW has)
+ *
+ * So those three bits have to be inside of 0-2nd LSB of PTE.
+ *
+ */
+
+#define _PAGE_PRESENT	0x00000001		/* S: PTE valid */
+#define _PAGE_RW	0x00000002		/* S: Write permission */
+#define _PAGE_FILE	0x00000004		/* S: nonlinear file mapping */
+#define _PAGE_HWEXEC	0x00000004		/* H: Execute permission */
+#define _PAGE_ACCESSED	0x00000008		/* S: Page referenced */
+#define _PAGE_DIRTY	0x00000010		/* S: Page dirty */
+#define _PAGE_SPECIAL	0x00000020		/* S: Special page */
+#define _PAGE_USER	0x00000040		/* S: User page */
+#define _PAGE_ENDIAN	0x00000080		/* H: E bit */
+#define _PAGE_GUARDED	0x00000100		/* H: G bit */
+#define _PAGE_COHERENT	0x00000200		/* H: M bit */
+#define _PAGE_NO_CACHE	0x00000400		/* H: I bit */
+#define _PAGE_WRITETHRU	0x00000800		/* H: W bit */
+
+/* TODO: Add large page lowmem mapping support */
+#define _PMD_PRESENT	0
+#define _PMD_PRESENT_MASK (PAGE_MASK)
+#define _PMD_BAD	(~PAGE_MASK)
+
+/* ERPN in a PTE never gets cleared, ignore it */
+#define _PTE_NONE_MASK	0xffffffff00000000ULL
+
+
+#endif /* __KERNEL__ */
+#endif /*  _ASM_POWERPC_PTE_44x_H */