1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_POWERPC_NOHASH_32_PTE_8xx_H 3 #define _ASM_POWERPC_NOHASH_32_PTE_8xx_H 4 #ifdef __KERNEL__ 5 6 /* 7 * The PowerPC MPC8xx uses a TLB with hardware assisted, software tablewalk. 8 * We also use the two level tables, but we can put the real bits in them 9 * needed for the TLB and tablewalk. These definitions require Mx_CTR.PPM = 0, 10 * Mx_CTR.PPCS = 0, and MD_CTR.TWAM = 1. The level 2 descriptor has 11 * additional page protection (when Mx_CTR.PPCS = 1) that allows TLB hit 12 * based upon user/super access. The TLB does not have accessed nor write 13 * protect. We assume that if the TLB get loaded with an entry it is 14 * accessed, and overload the changed bit for write protect. We use 15 * two bits in the software pte that are supposed to be set to zero in 16 * the TLB entry (24 and 25) for these indicators. Although the level 1 17 * descriptor contains the guarded and writethrough/copyback bits, we can 18 * set these at the page level since they get copied from the Mx_TWC 19 * register when the TLB entry is loaded. We will use bit 27 for guard, since 20 * that is where it exists in the MD_TWC, and bit 26 for writethrough. 21 * These will get masked from the level 2 descriptor at TLB load time, and 22 * copied to the MD_TWC before it gets loaded. 23 * Large page sizes added. We currently support two sizes, 4K and 8M. 24 * This also allows a TLB hander optimization because we can directly 25 * load the PMD into MD_TWC. The 8M pages are only used for kernel 26 * mapping of well known areas. The PMD (PGD) entries contain control 27 * flags in addition to the address, so care must be taken that the 28 * software no longer assumes these are only pointers. 29 */ 30 31 /* Definitions for 8xx embedded chips. */ 32 #define _PAGE_PRESENT 0x0001 /* Page is valid */ 33 #define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */ 34 #define _PAGE_PRIVILEGED 0x0004 /* No ASID (context) compare */ 35 #define _PAGE_HUGE 0x0008 /* SPS: Small Page Size (1 if 16k, 512k or 8M)*/ 36 #define _PAGE_DIRTY 0x0100 /* C: page changed */ 37 38 /* These 4 software bits must be masked out when the L2 entry is loaded 39 * into the TLB. 40 */ 41 #define _PAGE_GUARDED 0x0010 /* Copied to L1 G entry in DTLB */ 42 #define _PAGE_SPECIAL 0x0020 /* SW entry */ 43 #define _PAGE_EXEC 0x0040 /* Copied to PP (bit 21) in ITLB */ 44 #define _PAGE_ACCESSED 0x0080 /* software: page referenced */ 45 46 #define _PAGE_NA 0x0200 /* Supervisor NA, User no access */ 47 #define _PAGE_RO 0x0600 /* Supervisor RO, User no access */ 48 49 #define _PMD_PRESENT 0x0001 50 #define _PMD_BAD 0x0fd0 51 #define _PMD_PAGE_MASK 0x000c 52 #define _PMD_PAGE_8M 0x000c 53 #define _PMD_PAGE_512K 0x0004 54 #define _PMD_USER 0x0020 /* APG 1 */ 55 56 /* Until my rework is finished, 8xx still needs atomic PTE updates */ 57 #define PTE_ATOMIC_UPDATES 1 58 59 #ifdef CONFIG_PPC_16K_PAGES 60 #define _PAGE_PSIZE _PAGE_HUGE 61 #endif 62 63 #endif /* __KERNEL__ */ 64 #endif /* _ASM_POWERPC_NOHASH_32_PTE_8xx_H */ 65