diff options
Diffstat (limited to 'arch/powerpc/include/asm/pte-8xx.h')
| -rw-r--r-- | arch/powerpc/include/asm/pte-8xx.h | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/pte-8xx.h b/arch/powerpc/include/asm/pte-8xx.h new file mode 100644 index 000000000000..b07acfd330b0 --- /dev/null +++ b/arch/powerpc/include/asm/pte-8xx.h @@ -0,0 +1,64 @@ +#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 */ + +/* These five software bits must be masked out when the entry is loaded + * into the TLB. + */ +#define _PAGE_EXEC 0x0008 /* software: i-cache coherency required */ +#define _PAGE_GUARDED 0x0010 /* software: guarded access */ +#define _PAGE_DIRTY 0x0020 /* software: page changed */ +#define _PAGE_RW 0x0040 /* software: user write access allowed */ +#define _PAGE_ACCESSED 0x0080 /* software: page referenced */ + +/* 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_HWWRITE 0x0100 /* h/w write enable: never set in Linux PTE */ +#define _PAGE_USER 0x0800 /* One of the PP bits, the other is USER&~RW */ + +#define _PMD_PRESENT 0x0001 +#define _PMD_BAD 0x0ff0 +#define _PMD_PAGE_MASK 0x000c +#define _PMD_PAGE_8M 0x000c + +#define _PTE_NONE_MASK _PAGE_ACCESSED + +/* Until my rework is finished, 8xx still needs atomic PTE updates */ +#define PTE_ATOMIC_UPDATES 1 + + +#endif /* __KERNEL__ */ +#endif /* _ASM_POWERPC_PTE_8xx_H */ |