1 /*
2 * Copyright (C) 2005,2006,2007,2008,2009 Imagination Technologies
3 *
4 * Meta 1 MMU handling code.
5 *
6 */
7
8 #include <linux/sched.h>
9 #include <linux/mm.h>
10 #include <linux/io.h>
11
12 #include <asm/mmu.h>
13
14 #define DM3_BASE (LINSYSDIRECT_BASE + (MMCU_DIRECTMAPn_ADDR_SCALE * 3))
15
16 /*
17 * This contains the physical address of the top level 2k pgd table.
18 */
19 static unsigned long mmu_base_phys;
20
21 /*
22 * Given a physical address, return a mapped virtual address that can be used
23 * to access that location.
24 * In practice, we use the DirectMap region to make this happen.
25 */
map_addr(unsigned long phys)26 static unsigned long map_addr(unsigned long phys)
27 {
28 static unsigned long dm_base = 0xFFFFFFFF;
29 int offset;
30
31 offset = phys - dm_base;
32
33 /* Are we in the current map range ? */
34 if ((offset < 0) || (offset >= MMCU_DIRECTMAPn_ADDR_SCALE)) {
35 /* Calculate new DM area */
36 dm_base = phys & ~(MMCU_DIRECTMAPn_ADDR_SCALE - 1);
37
38 /* Actually map it in! */
39 metag_out32(dm_base, MMCU_DIRECTMAP3_ADDR);
40
41 /* And calculate how far into that area our reference is */
42 offset = phys - dm_base;
43 }
44
45 return DM3_BASE + offset;
46 }
47
48 /*
49 * Return the physical address of the base of our pgd table.
50 */
__get_mmu_base(void)51 static inline unsigned long __get_mmu_base(void)
52 {
53 unsigned long base_phys;
54 unsigned int stride;
55
56 if (is_global_space(PAGE_OFFSET))
57 stride = 4;
58 else
59 stride = hard_processor_id(); /* [0..3] */
60
61 base_phys = metag_in32(MMCU_TABLE_PHYS_ADDR);
62 base_phys += (0x800 * stride);
63
64 return base_phys;
65 }
66
67 /* Given a virtual address, return the virtual address of the relevant pgd */
pgd_entry_addr(unsigned long virt)68 static unsigned long pgd_entry_addr(unsigned long virt)
69 {
70 unsigned long pgd_phys;
71 unsigned long pgd_virt;
72
73 if (!mmu_base_phys)
74 mmu_base_phys = __get_mmu_base();
75
76 /*
77 * Are we trying to map a global address. If so, then index
78 * the global pgd table instead of our local one.
79 */
80 if (is_global_space(virt)) {
81 /* Scale into 2gig map */
82 virt &= ~0x80000000;
83 }
84
85 /* Base of the pgd table plus our 4Meg entry, 4bytes each */
86 pgd_phys = mmu_base_phys + ((virt >> PGDIR_SHIFT) * 4);
87
88 pgd_virt = map_addr(pgd_phys);
89
90 return pgd_virt;
91 }
92
93 /* Given a virtual address, return the virtual address of the relevant pte */
pgtable_entry_addr(unsigned long virt)94 static unsigned long pgtable_entry_addr(unsigned long virt)
95 {
96 unsigned long pgtable_phys;
97 unsigned long pgtable_virt, pte_virt;
98
99 /* Find the physical address of the 4MB page table*/
100 pgtable_phys = metag_in32(pgd_entry_addr(virt)) & MMCU_ENTRY_ADDR_BITS;
101
102 /* Map it to a virtual address */
103 pgtable_virt = map_addr(pgtable_phys);
104
105 /* And index into it for our pte */
106 pte_virt = pgtable_virt + ((virt >> PAGE_SHIFT) & 0x3FF) * 4;
107
108 return pte_virt;
109 }
110
mmu_read_first_level_page(unsigned long vaddr)111 unsigned long mmu_read_first_level_page(unsigned long vaddr)
112 {
113 return metag_in32(pgd_entry_addr(vaddr));
114 }
115
mmu_read_second_level_page(unsigned long vaddr)116 unsigned long mmu_read_second_level_page(unsigned long vaddr)
117 {
118 return metag_in32(pgtable_entry_addr(vaddr));
119 }
120
mmu_get_base(void)121 unsigned long mmu_get_base(void)
122 {
123 static unsigned long __base;
124
125 /* Find the base of our MMU pgd table */
126 if (!__base)
127 __base = pgd_entry_addr(0);
128
129 return __base;
130 }
131
mmu_init(unsigned long mem_end)132 void __init mmu_init(unsigned long mem_end)
133 {
134 unsigned long entry, addr;
135 pgd_t *p_swapper_pg_dir;
136
137 /*
138 * Now copy over any MMU pgd entries already in the mmu page tables
139 * over to our root init process (swapper_pg_dir) map. This map is
140 * then inherited by all other processes, which means all processes
141 * inherit a map of the kernel space.
142 */
143 addr = PAGE_OFFSET;
144 entry = pgd_index(PAGE_OFFSET);
145 p_swapper_pg_dir = pgd_offset_k(0) + entry;
146
147 while (addr <= META_MEMORY_LIMIT) {
148 unsigned long pgd_entry;
149 /* copy over the current MMU value */
150 pgd_entry = mmu_read_first_level_page(addr);
151 pgd_val(*p_swapper_pg_dir) = pgd_entry;
152
153 p_swapper_pg_dir++;
154 addr += PGDIR_SIZE;
155 entry++;
156 }
157 }
158