blob: d44826e4ff9772bf1a9b585d8466f03904030fc0 [file] [log] [blame]
#ifndef _ASM_POWERPC_PTE_8xx_H
#define _ASM_POWERPC_PTE_8xx_H
#ifdef __KERNEL__
* The PowerPC MPC8xx uses a TLB with hardware assisted, software tablewalk.
* We also use the two level tables, but we can put the real bits in them
* needed for the TLB and tablewalk. These definitions require Mx_CTR.PPM = 0,
* Mx_CTR.PPCS = 0, and MD_CTR.TWAM = 1. The level 2 descriptor has
* additional page protection (when Mx_CTR.PPCS = 1) that allows TLB hit
* based upon user/super access. The TLB does not have accessed nor write
* protect. We assume that if the TLB get loaded with an entry it is
* accessed, and overload the changed bit for write protect. We use
* two bits in the software pte that are supposed to be set to zero in
* the TLB entry (24 and 25) for these indicators. Although the level 1
* descriptor contains the guarded and writethrough/copyback bits, we can
* set these at the page level since they get copied from the Mx_TWC
* register when the TLB entry is loaded. We will use bit 27 for guard, since
* that is where it exists in the MD_TWC, and bit 26 for writethrough.
* These will get masked from the level 2 descriptor at TLB load time, and
* copied to the MD_TWC before it gets loaded.
* Large page sizes added. We currently support two sizes, 4K and 8M.
* This also allows a TLB hander optimization because we can directly
* load the PMD into MD_TWC. The 8M pages are only used for kernel
* mapping of well known areas. The PMD (PGD) entries contain control
* flags in addition to the address, so care must be taken that the
* software no longer assumes these are only pointers.
/* Definitions for 8xx embedded chips. */
#define _PAGE_PRESENT 0x0001 /* Page is valid */
#define _PAGE_FILE 0x0002 /* when !present: nonlinear file mapping */
#define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */
#define _PAGE_SHARED 0x0004 /* No ASID (context) compare */
#define _PAGE_SPECIAL 0x0008 /* SW entry, forced to 0 by the TLB miss */
#define _PAGE_DIRTY 0x0100 /* C: page changed */
/* These 4 software bits must be masked out when the entry is loaded
* into the TLB, 1 SW bit left(0x0080).
#define _PAGE_GUARDED 0x0010 /* software: guarded access */
#define _PAGE_ACCESSED 0x0020 /* software: page referenced */
#define _PAGE_WRITETHRU 0x0040 /* software: caching is write through */
/* Setting any bits in the nibble with the follow two controls will
* require a TLB exception handler change. It is assumed unused bits
* are always zero.
#define _PAGE_RW 0x0400 /* lsb PP bits, inverted in HW */
#define _PAGE_USER 0x0800 /* msb PP bits */
#define _PMD_PRESENT 0x0001
#define _PMD_BAD 0x0ff0
#define _PMD_PAGE_MASK 0x000c
#define _PMD_PAGE_8M 0x000c
/* Until my rework is finished, 8xx still needs atomic PTE updates */
/* We need to add _PAGE_SHARED to kernel pages */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_PTE_8xx_H */