m68k: page table support definitions and code for ColdFire MMU

The ColdFire V4e MMU is nothing like any of the other m68k MMU's.
So we need to create a set of definitions and support routines
for the kernels paging functions.

This is largely taken from Freescales BSP code for this (though it
was a 2.6.25 kernel). I have cleaned it up alot from the original.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Matt Waddel <mwaddel@yahoo.com>
Acked-by: Kurt Mahan <kmahan@xmission.com>

arch/m68k/include/asm/mcf_pgtable.h

+#ifndef _MCF_PGTABLE_H
+#define _MCF_PGTABLE_H
+
+#include <asm/mcfmmu.h>
+#include <asm/page.h>
+
+/*
+ * MMUDR bits, in proper place. We write these directly into the MMUDR
+ * after masking from the pte.
+ */
+#define CF_PAGE_LOCKED		MMUDR_LK	/* 0x00000002 */
+#define CF_PAGE_EXEC		MMUDR_X		/* 0x00000004 */
+#define CF_PAGE_WRITABLE	MMUDR_W		/* 0x00000008 */
+#define CF_PAGE_READABLE	MMUDR_R		/* 0x00000010 */
+#define CF_PAGE_SYSTEM		MMUDR_SP	/* 0x00000020 */
+#define CF_PAGE_COPYBACK	MMUDR_CM_CCB	/* 0x00000040 */
+#define CF_PAGE_NOCACHE		MMUDR_CM_NCP	/* 0x00000080 */
+
+#define CF_CACHEMASK		(~MMUDR_CM_CCB)
+#define CF_PAGE_MMUDR_MASK	0x000000fe
+
+#define _PAGE_NOCACHE030	CF_PAGE_NOCACHE
+
+/*
+ * MMUTR bits, need shifting down.
+ */
+#define CF_PAGE_MMUTR_MASK	0x00000c00
+#define CF_PAGE_MMUTR_SHIFT	10
+
+#define CF_PAGE_VALID		(MMUTR_V << CF_PAGE_MMUTR_SHIFT)
+#define CF_PAGE_SHARED		(MMUTR_SG << CF_PAGE_MMUTR_SHIFT)
+
+/*
+ * Fake bits, not implemented in CF, will get masked out before
+ * hitting hardware.
+ */
+#define CF_PAGE_DIRTY		0x00000001
+#define CF_PAGE_FILE		0x00000200
+#define CF_PAGE_ACCESSED	0x00001000
+
+#define _PAGE_CACHE040		0x020   /* 68040 cache mode, cachable, copyback */
+#define _PAGE_NOCACHE_S		0x040   /* 68040 no-cache mode, serialized */
+#define _PAGE_NOCACHE		0x060   /* 68040 cache mode, non-serialized */
+#define _PAGE_CACHE040W		0x000   /* 68040 cache mode, cachable, write-through */
+#define _DESCTYPE_MASK		0x003
+#define _CACHEMASK040		(~0x060)
+#define _PAGE_GLOBAL040		0x400   /* 68040 global bit, used for kva descs */
+
+/*
+ * Externally used page protection values.
+ */
+#define _PAGE_PRESENT	(CF_PAGE_VALID)
+#define _PAGE_ACCESSED	(CF_PAGE_ACCESSED)
+#define _PAGE_DIRTY	(CF_PAGE_DIRTY)
+#define _PAGE_READWRITE (CF_PAGE_READABLE \
+				| CF_PAGE_WRITABLE \
+				| CF_PAGE_SYSTEM \
+				| CF_PAGE_SHARED)
+
+/*
+ * Compound page protection values.
+ */
+#define PAGE_NONE	__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED)
+
+#define PAGE_SHARED     __pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_SHARED)
+
+#define PAGE_INIT	__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_WRITABLE \
+				 | CF_PAGE_EXEC \
+				 | CF_PAGE_SYSTEM)
+
+#define PAGE_KERNEL	__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_WRITABLE \
+				 | CF_PAGE_EXEC \
+				 | CF_PAGE_SYSTEM)
+
+#define PAGE_COPY	__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_DIRTY)
+
+/*
+ * Page protections for initialising protection_map. See mm/mmap.c
+ * for use. In general, the bit positions are xwr, and P-items are
+ * private, the S-items are shared.
+ */
+#define __P000		PAGE_NONE
+#define __P001		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE)
+#define __P010		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_WRITABLE)
+#define __P011		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_WRITABLE)
+#define __P100		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_EXEC)
+#define __P101		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_EXEC)
+#define __P110		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_WRITABLE \
+				 | CF_PAGE_EXEC)
+#define __P111		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_WRITABLE \
+				 | CF_PAGE_EXEC)
+
+#define __S000		PAGE_NONE
+#define __S001		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE)
+#define __S010		PAGE_SHARED
+#define __S011		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_SHARED \
+				 | CF_PAGE_READABLE)
+#define __S100		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_EXEC)
+#define __S101		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_EXEC)
+#define __S110		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_SHARED \
+				 | CF_PAGE_EXEC)
+#define __S111		__pgprot(CF_PAGE_VALID \
+				 | CF_PAGE_ACCESSED \
+				 | CF_PAGE_SHARED \
+				 | CF_PAGE_READABLE \
+				 | CF_PAGE_EXEC)
+
+#define PTE_MASK	PAGE_MASK
+#define CF_PAGE_CHG_MASK (PTE_MASK | CF_PAGE_ACCESSED | CF_PAGE_DIRTY)
+
+#ifndef __ASSEMBLY__
+
+/*
+ * Conversion functions: convert a page and protection to a page entry,
+ * and a page entry and page directory to the page they refer to.
+ */
+#define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
+
+static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
+{
+	pte_val(pte) = (pte_val(pte) & CF_PAGE_CHG_MASK) | pgprot_val(newprot);
+	return pte;
+}
+
+#define pmd_set(pmdp, ptep) do {} while (0)
+
+static inline void pgd_set(pgd_t *pgdp, pmd_t *pmdp)
+{
+	pgd_val(*pgdp) = virt_to_phys(pmdp);
+}
+
+#define __pte_page(pte)	((unsigned long) (pte_val(pte) & PAGE_MASK))
+#define __pmd_page(pmd)	((unsigned long) (pmd_val(pmd)))
+
+static inline int pte_none(pte_t pte)
+{
+	return !pte_val(pte);
+}
+
+static inline int pte_present(pte_t pte)
+{
+	return pte_val(pte) & CF_PAGE_VALID;
+}
+
+static inline void pte_clear(struct mm_struct *mm, unsigned long addr,
+	pte_t *ptep)
+{
+	pte_val(*ptep) = 0;
+}
+
+#define pte_pagenr(pte)	((__pte_page(pte) - PAGE_OFFSET) >> PAGE_SHIFT)
+#define pte_page(pte)	virt_to_page(__pte_page(pte))
+
+static inline int pmd_none2(pmd_t *pmd) { return !pmd_val(*pmd); }
+#define pmd_none(pmd) pmd_none2(&(pmd))
+static inline int pmd_bad2(pmd_t *pmd) { return 0; }
+#define pmd_bad(pmd) pmd_bad2(&(pmd))
+#define pmd_present(pmd) (!pmd_none2(&(pmd)))
+static inline void pmd_clear(pmd_t *pmdp) { pmd_val(*pmdp) = 0; }
+
+static inline int pgd_none(pgd_t pgd) { return 0; }
+static inline int pgd_bad(pgd_t pgd) { return 0; }
+static inline int pgd_present(pgd_t pgd) { return 1; }
+static inline void pgd_clear(pgd_t *pgdp) {}
+
+#define pte_ERROR(e) \
+	printk(KERN_ERR "%s:%d: bad pte %08lx.\n",	\
+	__FILE__, __LINE__, pte_val(e))
+#define pmd_ERROR(e) \
+	printk(KERN_ERR "%s:%d: bad pmd %08lx.\n",	\
+	__FILE__, __LINE__, pmd_val(e))
+#define pgd_ERROR(e) \
+	printk(KERN_ERR "%s:%d: bad pgd %08lx.\n",	\
+	__FILE__, __LINE__, pgd_val(e))
+
+/*
+ * The following only work if pte_present() is true.
+ * Undefined behaviour if not...
+ * [we have the full set here even if they don't change from m68k]
+ */
+static inline int pte_read(pte_t pte)
+{
+	return pte_val(pte) & CF_PAGE_READABLE;
+}
+
+static inline int pte_write(pte_t pte)
+{
+	return pte_val(pte) & CF_PAGE_WRITABLE;
+}
+
+static inline int pte_exec(pte_t pte)
+{
+	return pte_val(pte) & CF_PAGE_EXEC;
+}
+
+static inline int pte_dirty(pte_t pte)
+{
+	return pte_val(pte) & CF_PAGE_DIRTY;
+}
+
+static inline int pte_young(pte_t pte)
+{
+	return pte_val(pte) & CF_PAGE_ACCESSED;
+}
+
+static inline int pte_file(pte_t pte)
+{
+	return pte_val(pte) & CF_PAGE_FILE;
+}
+
+static inline int pte_special(pte_t pte)
+{
+	return 0;
+}
+
+static inline pte_t pte_wrprotect(pte_t pte)
+{
+	pte_val(pte) &= ~CF_PAGE_WRITABLE;
+	return pte;
+}
+
+static inline pte_t pte_rdprotect(pte_t pte)
+{
+	pte_val(pte) &= ~CF_PAGE_READABLE;
+	return pte;
+}
+
+static inline pte_t pte_exprotect(pte_t pte)
+{
+	pte_val(pte) &= ~CF_PAGE_EXEC;
+	return pte;
+}
+
+static inline pte_t pte_mkclean(pte_t pte)
+{
+	pte_val(pte) &= ~CF_PAGE_DIRTY;
+	return pte;
+}
+
+static inline pte_t pte_mkold(pte_t pte)
+{
+	pte_val(pte) &= ~CF_PAGE_ACCESSED;
+	return pte;
+}
+
+static inline pte_t pte_mkwrite(pte_t pte)
+{
+	pte_val(pte) |= CF_PAGE_WRITABLE;
+	return pte;
+}
+
+static inline pte_t pte_mkread(pte_t pte)
+{
+	pte_val(pte) |= CF_PAGE_READABLE;
+	return pte;
+}
+
+static inline pte_t pte_mkexec(pte_t pte)
+{
+	pte_val(pte) |= CF_PAGE_EXEC;
+	return pte;
+}
+
+static inline pte_t pte_mkdirty(pte_t pte)
+{
+	pte_val(pte) |= CF_PAGE_DIRTY;
+	return pte;
+}
+
+static inline pte_t pte_mkyoung(pte_t pte)
+{
+	pte_val(pte) |= CF_PAGE_ACCESSED;
+	return pte;
+}
+
+static inline pte_t pte_mknocache(pte_t pte)
+{
+	pte_val(pte) |= 0x80 | (pte_val(pte) & ~0x40);
+	return pte;
+}
+
+static inline pte_t pte_mkcache(pte_t pte)
+{
+	pte_val(pte) &= ~CF_PAGE_NOCACHE;
+	return pte;
+}
+
+static inline pte_t pte_mkspecial(pte_t pte)
+{
+	return pte;
+}
+
+#define swapper_pg_dir kernel_pg_dir
+extern pgd_t kernel_pg_dir[PTRS_PER_PGD];
+
+/*
+ * Find an entry in a pagetable directory.
+ */
+#define pgd_index(address)	((address) >> PGDIR_SHIFT)
+#define pgd_offset(mm, address)	((mm)->pgd + pgd_index(address))
+
+/*
+ * Find an entry in a kernel pagetable directory.
+ */
+#define pgd_offset_k(address)	pgd_offset(&init_mm, address)
+
+/*
+ * Find an entry in the second-level pagetable.
+ */
+static inline pmd_t *pmd_offset(pgd_t *pgd, unsigned long address)
+{
+	return (pmd_t *) pgd;
+}
+
+/*
+ * Find an entry in the third-level pagetable.
+ */
+#define __pte_offset(address)	((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
+#define pte_offset_kernel(dir, address) \
+	((pte_t *) __pmd_page(*(dir)) + __pte_offset(address))
+
+/*
+ * Disable caching for page at given kernel virtual address.
+ */
+static inline void nocache_page(void *vaddr)
+{
+	pgd_t *dir;
+	pmd_t *pmdp;
+	pte_t *ptep;
+	unsigned long addr = (unsigned long) vaddr;
+
+	dir = pgd_offset_k(addr);
+	pmdp = pmd_offset(dir, addr);
+	ptep = pte_offset_kernel(pmdp, addr);
+	*ptep = pte_mknocache(*ptep);
+}
+
+/*
+ * Enable caching for page at given kernel virtual address.
+ */
+static inline void cache_page(void *vaddr)
+{
+	pgd_t *dir;
+	pmd_t *pmdp;
+	pte_t *ptep;
+	unsigned long addr = (unsigned long) vaddr;
+
+	dir = pgd_offset_k(addr);
+	pmdp = pmd_offset(dir, addr);
+	ptep = pte_offset_kernel(pmdp, addr);
+	*ptep = pte_mkcache(*ptep);
+}
+
+#define PTE_FILE_MAX_BITS	21
+#define PTE_FILE_SHIFT		11
+
+static inline unsigned long pte_to_pgoff(pte_t pte)
+{
+	return pte_val(pte) >> PTE_FILE_SHIFT;
+}
+
+static inline pte_t pgoff_to_pte(unsigned pgoff)
+{
+	return __pte((pgoff << PTE_FILE_SHIFT) + CF_PAGE_FILE);
+}
+
+/*
+ * Encode and de-code a swap entry (must be !pte_none(e) && !pte_present(e))
+ */
+#define __swp_type(x)		((x).val & 0xFF)
+#define __swp_offset(x)		((x).val >> PTE_FILE_SHIFT)
+#define __swp_entry(typ, off)	((swp_entry_t) { (typ) | \
+					(off << PTE_FILE_SHIFT) })
+#define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
+#define __swp_entry_to_pte(x)	(__pte((x).val))
+
+#define pmd_page(pmd)		(pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT))
+
+#define pte_offset_map(pmdp, addr) ((pte_t *)__pmd_page(*pmdp) + \
+				       __pte_offset(addr))
+#define pte_unmap(pte)		((void) 0)
+#define pfn_pte(pfn, prot)	__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
+#define pte_pfn(pte)		(pte_val(pte) >> PAGE_SHIFT)
+
+#endif	/* !__ASSEMBLY__ */
+#endif	/* _MCF_PGTABLE_H */