1 // SPDX-License-Identifier: GPL-2.0
3 * Based upon linux/arch/m68k/mm/sun3mmu.c
4 * Based upon linux/arch/ppc/mm/mmu_context.c
6 * Implementations of mm routines specific to the Coldfire MMU.
8 * Copyright (c) 2008 Freescale Semiconductor, Inc.
11 #include <linux/kernel.h>
12 #include <linux/types.h>
14 #include <linux/init.h>
15 #include <linux/string.h>
16 #include <linux/bootmem.h>
17 #include <linux/memblock.h>
19 #include <asm/setup.h>
21 #include <asm/pgtable.h>
22 #include <asm/mmu_context.h>
23 #include <asm/mcf_pgalloc.h>
24 #include <asm/tlbflush.h>
26 #define KMAPAREA(x) ((x >= VMALLOC_START) && (x < KMAP_END))
28 mm_context_t next_mmu_context;
29 unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
30 atomic_t nr_free_contexts;
31 struct mm_struct *context_mm[LAST_CONTEXT+1];
32 unsigned long num_pages;
35 * ColdFire paging_init derived from sun3.
37 void __init paging_init(void)
41 unsigned long address, size;
42 unsigned long next_pgtable, bootmem_end;
43 unsigned long zones_size[MAX_NR_ZONES];
47 empty_zero_page = (void *) alloc_bootmem_pages(PAGE_SIZE);
48 memset((void *) empty_zero_page, 0, PAGE_SIZE);
50 pg_dir = swapper_pg_dir;
51 memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
53 size = num_pages * sizeof(pte_t);
54 size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
55 next_pgtable = (unsigned long) alloc_bootmem_pages(size);
57 bootmem_end = (next_pgtable + size + PAGE_SIZE) & PAGE_MASK;
58 pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
60 address = PAGE_OFFSET;
61 while (address < (unsigned long)high_memory) {
62 pg_table = (pte_t *) next_pgtable;
63 next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
64 pgd_val(*pg_dir) = (unsigned long) pg_table;
67 /* now change pg_table to kernel virtual addresses */
68 for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
69 pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
70 if (address >= (unsigned long) high_memory)
73 set_pte(pg_table, pte);
80 for (zone = 0; zone < MAX_NR_ZONES; zone++)
81 zones_size[zone] = 0x0;
82 zones_size[ZONE_DMA] = num_pages;
83 free_area_init(zones_size);
86 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
88 unsigned long flags, mmuar, mmutr;
95 local_irq_save(flags);
97 mmuar = (dtlb) ? mmu_read(MMUAR) :
98 regs->pc + (extension_word * sizeof(long));
100 mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
102 local_irq_restore(flags);
106 pgd = pgd_offset(mm, mmuar);
107 if (pgd_none(*pgd)) {
108 local_irq_restore(flags);
112 pmd = pmd_offset(pgd, mmuar);
113 if (pmd_none(*pmd)) {
114 local_irq_restore(flags);
118 pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
119 : pte_offset_map(pmd, mmuar);
120 if (pte_none(*pte) || !pte_present(*pte)) {
121 local_irq_restore(flags);
126 if (!pte_write(*pte)) {
127 local_irq_restore(flags);
130 set_pte(pte, pte_mkdirty(*pte));
133 set_pte(pte, pte_mkyoung(*pte));
134 asid = mm->context & 0xff;
135 if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
136 set_pte(pte, pte_wrprotect(*pte));
138 mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
139 if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
140 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
141 mmu_write(MMUTR, mmutr);
143 mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
144 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
147 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
149 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
151 local_irq_restore(flags);
155 void __init cf_bootmem_alloc(void)
157 unsigned long memstart;
159 /* _rambase and _ramend will be naturally page aligned */
160 m68k_memory[0].addr = _rambase;
161 m68k_memory[0].size = _ramend - _rambase;
163 memblock_add(m68k_memory[0].addr, m68k_memory[0].size);
165 /* compute total pages in system */
166 num_pages = PFN_DOWN(_ramend - _rambase);
169 memstart = PAGE_ALIGN(_ramstart);
170 min_low_pfn = PFN_DOWN(_rambase);
171 max_pfn = max_low_pfn = PFN_DOWN(_ramend);
172 high_memory = (void *)_ramend;
174 /* Reserve kernel text/data/bss */
175 memblock_reserve(memstart, memstart - _rambase);
177 m68k_virt_to_node_shift = fls(_ramend - 1) - 6;
178 module_fixup(NULL, __start_fixup, __stop_fixup);
180 /* setup node data */
185 * Initialize the context management stuff.
186 * The following was taken from arch/ppc/mmu_context.c
188 void __init cf_mmu_context_init(void)
191 * Some processors have too few contexts to reserve one for
192 * init_mm, and require using context 0 for a normal task.
193 * Other processors reserve the use of context zero for the kernel.
194 * This code assumes FIRST_CONTEXT < 32.
196 context_map[0] = (1 << FIRST_CONTEXT) - 1;
197 next_mmu_context = FIRST_CONTEXT;
198 atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
202 * Steal a context from a task that has one at the moment.
203 * This is only used on 8xx and 4xx and we presently assume that
204 * they don't do SMP. If they do then thicfpgalloc.hs will have to check
205 * whether the MM we steal is in use.
206 * We also assume that this is only used on systems that don't
207 * use an MMU hash table - this is true for 8xx and 4xx.
208 * This isn't an LRU system, it just frees up each context in
209 * turn (sort-of pseudo-random replacement :). This would be the
210 * place to implement an LRU scheme if anyone was motivated to do it.
213 void steal_context(void)
215 struct mm_struct *mm;
217 * free up context `next_mmu_context'
218 * if we shouldn't free context 0, don't...
220 if (next_mmu_context < FIRST_CONTEXT)
221 next_mmu_context = FIRST_CONTEXT;
222 mm = context_mm[next_mmu_context];