1/*
2 *  linux/arch/arm26/mm/memc.c
3 *
4 *  Copyright (C) 1998-2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 *  Page table sludge for older ARM processor architectures.
11 */
12#include <linux/sched.h>
13#include <linux/mm.h>
14#include <linux/init.h>
15#include <linux/bootmem.h>
16
17#include <asm/pgtable.h>
18#include <asm/pgalloc.h>
19#include <asm/page.h>
20#include <asm/memory.h>
21#include <asm/hardware.h>
22
23#include <asm/map.h>
24
25#define MEMC_TABLE_SIZE (256*sizeof(unsigned long))
26
27struct kmem_cache *pte_cache, *pgd_cache;
28int page_nr;
29
30/*
31 * Allocate space for a page table and a MEMC table.
32 * Note that we place the MEMC
33 * table before the page directory.  This means we can
34 * easily get to both tightly-associated data structures
35 * with a single pointer.
36 */
37static inline pgd_t *alloc_pgd_table(void)
38{
39	void *pg2k = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
40
41	if (pg2k)
42		pg2k += MEMC_TABLE_SIZE;
43
44	return (pgd_t *)pg2k;
45}
46
47/*
48 * Free a page table. this function is the counterpart to get_pgd_slow
49 * below, not alloc_pgd_table above.
50 */
51void free_pgd_slow(pgd_t *pgd)
52{
53	unsigned long tbl = (unsigned long)pgd;
54
55	tbl -= MEMC_TABLE_SIZE;
56
57	kmem_cache_free(pgd_cache, (void *)tbl);
58}
59
60/*
61 * Allocate a new pgd and fill it in ready for use
62 *
63 * A new tasks pgd is completely empty (all pages !present) except for:
64 *
65 * o The machine vectors at virtual address 0x0
66 * o The vmalloc region at the top of address space
67 *
68 */
69#define FIRST_KERNEL_PGD_NR     (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
70
71pgd_t *get_pgd_slow(struct mm_struct *mm)
72{
73	pgd_t *new_pgd, *init_pgd;
74	pmd_t *new_pmd, *init_pmd;
75	pte_t *new_pte, *init_pte;
76
77	new_pgd = alloc_pgd_table();
78	if (!new_pgd)
79		goto no_pgd;
80
81	/*
82	 * On ARM, first page must always be allocated since it contains
83	 * the machine vectors.
84	 */
85	new_pmd = pmd_alloc(mm, new_pgd, 0);
86	if (!new_pmd)
87		goto no_pmd;
88
89	new_pte = pte_alloc_map(mm, new_pmd, 0);
90	if (!new_pte)
91		goto no_pte;
92
93	init_pgd = pgd_offset(&init_mm, 0);
94	init_pmd = pmd_offset(init_pgd, 0);
95	init_pte = pte_offset(init_pmd, 0);
96
97	set_pte(new_pte, *init_pte);
98	pte_unmap(new_pte);
99
100	/*
101	 * the page table entries are zeroed
102	 * when the table is created. (see the cache_ctor functions below)
103	 * Now we need to plonk the kernel (vmalloc) area at the end of
104	 * the address space. We copy this from the init thread, just like
105	 * the init_pte we copied above...
106	 */
107	memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
108		(PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
109
110	/* update MEMC tables */
111	cpu_memc_update_all(new_pgd);
112	return new_pgd;
113
114no_pte:
115	pmd_free(new_pmd);
116no_pmd:
117	free_pgd_slow(new_pgd);
118no_pgd:
119	return NULL;
120}
121
122/*
123 * No special code is required here.
124 */
125void setup_mm_for_reboot(char mode)
126{
127}
128
129void __init memtable_init(struct meminfo *mi)
130{
131	pte_t *pte;
132	int i;
133
134	page_nr = max_low_pfn;
135
136	pte = alloc_bootmem_low_pages(PTRS_PER_PTE * sizeof(pte_t));
137	pte[0] = mk_pte_phys(PAGE_OFFSET + SCREEN_SIZE, PAGE_READONLY);
138	pmd_populate(&init_mm, pmd_offset(swapper_pg_dir, 0), pte);
139
140	for (i = 1; i < PTRS_PER_PGD; i++)
141		pgd_val(swapper_pg_dir[i]) = 0;
142}
143
144void __init iotable_init(struct map_desc *io_desc)
145{
146	/* nothing to do */
147}
148
149/*
150 * We never have holes in the memmap
151 */
152void __init create_memmap_holes(struct meminfo *mi)
153{
154}
155
156static void pte_cache_ctor(void *pte, struct kmem_cache *cache, unsigned long flags)
157{
158	memzero(pte, sizeof(pte_t) * PTRS_PER_PTE);
159}
160
161static void pgd_cache_ctor(void *pgd, struct kmem_cache *cache, unsigned long flags)
162{
163	memzero(pgd + MEMC_TABLE_SIZE, USER_PTRS_PER_PGD * sizeof(pgd_t));
164}
165
166void __init pgtable_cache_init(void)
167{
168	pte_cache = kmem_cache_create("pte-cache",
169				sizeof(pte_t) * PTRS_PER_PTE,
170				0, SLAB_PANIC, pte_cache_ctor, NULL);
171
172	pgd_cache = kmem_cache_create("pgd-cache", MEMC_TABLE_SIZE +
173				sizeof(pgd_t) * PTRS_PER_PGD,
174				0, SLAB_PANIC, pgd_cache_ctor, NULL);
175}
176