1#ifndef _ASM_POWERPC_PTE_8xx_H 2#define _ASM_POWERPC_PTE_8xx_H 3#ifdef __KERNEL__ 4 5/* 6 * The PowerPC MPC8xx uses a TLB with hardware assisted, software tablewalk. 7 * We also use the two level tables, but we can put the real bits in them 8 * needed for the TLB and tablewalk. These definitions require Mx_CTR.PPM = 0, 9 * Mx_CTR.PPCS = 0, and MD_CTR.TWAM = 1. The level 2 descriptor has 10 * additional page protection (when Mx_CTR.PPCS = 1) that allows TLB hit 11 * based upon user/super access. The TLB does not have accessed nor write 12 * protect. We assume that if the TLB get loaded with an entry it is 13 * accessed, and overload the changed bit for write protect. We use 14 * two bits in the software pte that are supposed to be set to zero in 15 * the TLB entry (24 and 25) for these indicators. Although the level 1 16 * descriptor contains the guarded and writethrough/copyback bits, we can 17 * set these at the page level since they get copied from the Mx_TWC 18 * register when the TLB entry is loaded. We will use bit 27 for guard, since 19 * that is where it exists in the MD_TWC, and bit 26 for writethrough. 20 * These will get masked from the level 2 descriptor at TLB load time, and 21 * copied to the MD_TWC before it gets loaded. 22 * Large page sizes added. We currently support two sizes, 4K and 8M. 23 * This also allows a TLB hander optimization because we can directly 24 * load the PMD into MD_TWC. The 8M pages are only used for kernel 25 * mapping of well known areas. The PMD (PGD) entries contain control 26 * flags in addition to the address, so care must be taken that the 27 * software no longer assumes these are only pointers. 28 */ 29 30/* Definitions for 8xx embedded chips. */ 31#define _PAGE_PRESENT 0x0001 /* Page is valid */ 32#define _PAGE_FILE 0x0002 /* when !present: nonlinear file mapping */ 33#define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */ 34#define _PAGE_SHARED 0x0004 /* No ASID (context) compare */ 35#define _PAGE_SPECIAL 0x0008 /* SW entry, forced to 0 by the TLB miss */ 36#define _PAGE_DIRTY 0x0100 /* C: page changed */ 37 38/* These 4 software bits must be masked out when the entry is loaded 39 * into the TLB, 1 SW bit left(0x0080). 40 */ 41#define _PAGE_GUARDED 0x0010 /* software: guarded access */ 42#define _PAGE_ACCESSED 0x0020 /* software: page referenced */ 43#define _PAGE_WRITETHRU 0x0040 /* software: caching is write through */ 44 45/* Setting any bits in the nibble with the follow two controls will 46 * require a TLB exception handler change. It is assumed unused bits 47 * are always zero. 48 */ 49#define _PAGE_RW 0x0400 /* lsb PP bits, inverted in HW */ 50#define _PAGE_USER 0x0800 /* msb PP bits */ 51 52#define _PMD_PRESENT 0x0001 53#define _PMD_BAD 0x0ff0 54#define _PMD_PAGE_MASK 0x000c 55#define _PMD_PAGE_8M 0x000c 56 57#define _PTE_NONE_MASK _PAGE_ACCESSED 58 59/* Until my rework is finished, 8xx still needs atomic PTE updates */ 60#define PTE_ATOMIC_UPDATES 1 61 62/* We need to add _PAGE_SHARED to kernel pages */ 63#define _PAGE_KERNEL_RO (_PAGE_SHARED) 64#define _PAGE_KERNEL_RW (_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE) 65 66#endif /* __KERNEL__ */ 67#endif /* _ASM_POWERPC_PTE_8xx_H */ 68