1 files changed, 64 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/pte-40x.h b/arch/powerpc/include/asm/pte-40x.h
new file mode 100644
index 000000000000..07630faae029
--- /dev/null
+++ b/arch/powerpc/include/asm/pte-40x.h
@@ -0,0 +1,64 @@
+#ifndef _ASM_POWERPC_PTE_40x_H
+#define _ASM_POWERPC_PTE_40x_H
+#ifdef __KERNEL__
+
+/*
+ * At present, all PowerPC 400-class processors share a similar TLB
+ * architecture. The instruction and data sides share a unified,
+ * 64-entry, fully-associative TLB which is maintained totally under
+ * software control. In addition, the instruction side has a
+ * hardware-managed, 4-entry, fully-associative TLB which serves as a
+ * first level to the shared TLB. These two TLBs are known as the UTLB
+ * and ITLB, respectively (see "mmu.h" for definitions).
+ *
+ * There are several potential gotchas here.  The 40x hardware TLBLO
+ * field looks like this:
+ *
+ * 0  1  2  3  4  ... 18 19 20 21 22 23 24 25 26 27 28 29 30 31
+ * RPN.....................  0  0 EX WR ZSEL.......  W  I  M  G
+ *
+ * Where possible we make the Linux PTE bits match up with this
+ *
+ * - bits 20 and 21 must be cleared, because we use 4k pages (40x can
+ *   support down to 1k pages), this is done in the TLBMiss exception
+ *   handler.
+ * - We use only zones 0 (for kernel pages) and 1 (for user pages)
+ *   of the 16 available.  Bit 24-26 of the TLB are cleared in the TLB
+ *   miss handler.  Bit 27 is PAGE_USER, thus selecting the correct
+ *   zone.
+ * - PRESENT *must* be in the bottom two bits because swap cache
+ *   entries use the top 30 bits.  Because 40x doesn't support SMP
+ *   anyway, M is irrelevant so we borrow it for PAGE_PRESENT.  Bit 30
+ *   is cleared in the TLB miss handler before the TLB entry is loaded.
+ * - All other bits of the PTE are loaded into TLBLO without
+ *   modification, leaving us only the bits 20, 21, 24, 25, 26, 30 for
+ *   software PTE bits.  We actually use use bits 21, 24, 25, and
+ *   30 respectively for the software bits: ACCESSED, DIRTY, RW, and
+ *   PRESENT.
+ */
+
+#define _PAGE_GUARDED   0x001   /* G: page is guarded from prefetch */
+#define _PAGE_FILE      0x001   /* when !present: nonlinear file mapping */
+#define _PAGE_PRESENT   0x002   /* software: PTE contains a translation */
+#define _PAGE_NO_CACHE  0x004   /* I: caching is inhibited */
+#define _PAGE_WRITETHRU 0x008   /* W: caching is write-through */
+#define _PAGE_USER      0x010   /* matches one of the zone permission bits */
+#define _PAGE_RW        0x040   /* software: Writes permitted */
+#define _PAGE_DIRTY     0x080   /* software: dirty page */
+#define _PAGE_HWWRITE   0x100   /* hardware: Dirty & RW, set in exception */
+#define _PAGE_HWEXEC    0x200   /* hardware: EX permission */
+#define _PAGE_ACCESSED  0x400   /* software: R: page referenced */
+
+#define _PMD_PRESENT    0x400   /* PMD points to page of PTEs */
+#define _PMD_BAD        0x802
+#define _PMD_SIZE       0x0e0   /* size field, != 0 for large-page PMD entry */
+#define _PMD_SIZE_4M    0x0c0
+#define _PMD_SIZE_16M   0x0e0
+
+#define PMD_PAGE_SIZE(pmdval)   (1024 << (((pmdval) & _PMD_SIZE) >> 4))
+
+/* Until my rework is finished, 40x still needs atomic PTE updates */
+#define PTE_ATOMIC_UPDATES      1
+
+#endif /* __KERNEL__ */
+#endif /*  _ASM_POWERPC_PTE_40x_H */