Root/target/linux/coldfire/files-2.6.31/arch/m68k/mm/cf-mmu.c

1/*
2 * linux/arch/m68k/mm/cf-mmu.c
3 *
4 * Based upon linux/arch/m68k/mm/sun3mmu.c
5 * Based upon linux/arch/ppc/mm/mmu_context.c
6 *
7 * Implementations of mm routines specific to the Coldfire MMU.
8 *
9 * Copyright (c) 2008 Freescale Semiconductor, Inc.
10 * Copyright Freescale Semiconductor, Inc. 2008-2009
11 * Jason Jin Jason.Jin@freescale.com
12 * Shrek Wu B16972@freescale.com
13 */
14
15#include <linux/signal.h>
16#include <linux/sched.h>
17#include <linux/mm.h>
18#include <linux/swap.h>
19#include <linux/kernel.h>
20#include <linux/string.h>
21#include <linux/types.h>
22#include <linux/init.h>
23#ifdef CONFIG_BLK_DEV_RAM
24#include <linux/blkdev.h>
25#endif
26#include <linux/bootmem.h>
27
28#include <asm/setup.h>
29#include <asm/uaccess.h>
30#include <asm/page.h>
31#include <asm/pgtable.h>
32#include <asm/system.h>
33#include <asm/machdep.h>
34#include <asm/io.h>
35#include <asm/mmu_context.h>
36#include <asm/cf_pgalloc.h>
37
38#include <asm/coldfire.h>
39#include <asm/tlbflush.h>
40
41#define KMAPAREA(x) ((x >= VMALLOC_START) && (x < KMAP_END))
42
43#undef DEBUG
44
45#ifdef CONFIG_VDSO
46unsigned long next_mmu_context;
47#else
48mm_context_t next_mmu_context;
49#endif
50
51unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
52
53atomic_t nr_free_contexts;
54struct mm_struct *context_mm[LAST_CONTEXT+1];
55void steal_context(void);
56#ifdef CONFIG_M5445X
57void m68k_setup_node(int);
58#endif
59const char bad_pmd_string[] = "Bad pmd in pte_alloc: %08lx\n";
60
61extern unsigned long empty_bad_page_table;
62extern unsigned long empty_bad_page;
63extern unsigned long num_pages;
64#ifdef CONFIG_M5445X
65extern unsigned long availmem;
66#endif
67extern char __init_begin, __init_end;
68
69/*
70 * Free memory used for system initialization.
71 */
72void free_initmem(void)
73{
74#if 0
75    unsigned long addr;
76    unsigned long start = (unsigned long)&__init_begin;
77    unsigned long end = (unsigned long)&__init_end;
78
79    printk(KERN_INFO "free_initmem: __init_begin = 0x%lx __init_end = 0x%lx\n", start, end);
80
81    addr = (unsigned long)&__init_begin;
82    for (; addr < (unsigned long)&__init_end; addr += PAGE_SIZE) {
83        /* not currently used */
84        virt_to_page(addr)->flags &= ~(1 << PG_reserved);
85        init_page_count(virt_to_page(addr));
86        free_page(addr);
87        totalram_pages++;
88    }
89#endif
90}
91
92/*
93 * Initialize the paging system.
94 */
95void __init paging_init(void)
96{
97    pgd_t * pg_dir;
98    pte_t * pg_table;
99    int i;
100    unsigned long address;
101    unsigned long next_pgtable;
102    unsigned long zones_size[MAX_NR_ZONES];
103    unsigned long size;
104    enum zone_type zone;
105
106    /* allocate zero page */
107    empty_zero_page = (void *)alloc_bootmem_pages(PAGE_SIZE);
108    memset((void *)empty_zero_page, 0, PAGE_SIZE);
109
110    /* zero kernel page directory */
111    pg_dir = swapper_pg_dir;
112    memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
113    /*
114     * setup page tables for PHYSRAM
115     */
116
117    /* starting loc in page directory */
118    pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
119
120    /* allocate page tables */
121    size = num_pages * sizeof(pte_t);
122    size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
123    next_pgtable = (unsigned long)alloc_bootmem_pages(size);
124    address = PAGE_OFFSET;
125    while (address < (unsigned long)high_memory) {
126        /* setup page table in page directory */
127            pg_table = (pte_t *)next_pgtable;
128            next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
129        pgd_val(*pg_dir) = (unsigned long)pg_table;
130        pg_dir++;
131
132        /* create PTEs in page table */
133        for (i=0; i<PTRS_PER_PTE; ++i, ++pg_table) {
134            pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
135            if (address >= (unsigned long)high_memory)
136                pte_val (pte) = 0;
137
138            set_pte(pg_table, pte);
139            address += PAGE_SIZE;
140        }
141    }
142
143    /*
144     * setup page tables for DMA area
145     */
146
147    /* starting loc in page directory */
148    pg_dir = swapper_pg_dir;
149    pg_dir += CONFIG_DMA_BASE >> PGDIR_SHIFT;
150
151    /* allocate page tables */
152    size = (CONFIG_DMA_SIZE >> PAGE_SHIFT) * sizeof(pte_t);
153    size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
154    next_pgtable = (unsigned long)alloc_bootmem_pages(size);
155    address = CONFIG_DMA_BASE;
156    while (address < (CONFIG_DMA_BASE + CONFIG_DMA_SIZE)) {
157        /* setup page table in page directory */
158            pg_table = (pte_t *)next_pgtable;
159            next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
160        pgd_val(*pg_dir) = (unsigned long)pg_table;
161        pg_dir++;
162
163        /* create PTEs in page table */
164        for (i=0; i<PTRS_PER_PTE; ++i, ++pg_table) {
165            pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
166            if (address >= (CONFIG_DMA_BASE + CONFIG_DMA_SIZE))
167                pte_val (pte) = 0;
168
169            set_pte(pg_table, pte);
170            address += PAGE_SIZE;
171        }
172    }
173
174    /*
175     * setup zones
176     */
177
178    current->mm = NULL;
179
180    /* clear zones */
181    for (zone = 0; zone < MAX_NR_ZONES; zone++)
182        zones_size[zone] = 0x0;
183
184    zones_size[ZONE_DMA] = CONFIG_DMA_SIZE >> PAGE_SHIFT;
185    zones_size[ZONE_NORMAL] = (((unsigned long)high_memory -
186                    PAGE_OFFSET) >> PAGE_SHIFT) -
187                   zones_size[ZONE_DMA];
188
189    free_area_init(zones_size);
190}
191/*
192 * Handle a missed TLB
193 */
194int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
195{
196        struct mm_struct *mm;
197        pgd_t *pgd;
198        pmd_t *pmd;
199        pte_t *pte;
200        unsigned long mmuar;
201        int asid;
202    int flags;
203
204    local_save_flags(flags);
205    local_irq_disable();
206
207    mmuar = ( dtlb ) ? regs->mmuar
208             : regs->pc + (extension_word * sizeof(long));
209
210        mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
211
212        if (!mm) {
213        local_irq_restore(flags);
214        return (-1);
215    }
216
217        pgd = pgd_offset(mm, mmuar);
218        if (pgd_none(*pgd)) {
219        local_irq_restore(flags);
220        return (-1);
221    }
222        
223        pmd = pmd_offset(pgd, mmuar);
224        if (pmd_none(*pmd)) {
225        local_irq_restore(flags);
226        return (-1);
227    }
228    
229    pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
230                           : pte_offset_map(pmd, mmuar);
231        if (pte_none(*pte) || !pte_present(*pte)) {
232        local_irq_restore(flags);
233        return (-1);
234    }
235
236    if (write) {
237            if (!pte_write(*pte)) {
238        local_irq_restore(flags);
239            return (-1);
240        }
241            set_pte(pte, pte_mkdirty(*pte));
242    }
243    
244        set_pte(pte, pte_mkyoung(*pte));
245        asid = cpu_context(mm) & 0xff;
246        if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
247            set_pte(pte, pte_wrprotect(*pte));
248
249        *MMUTR = (mmuar & PAGE_MASK) | (asid << CF_ASID_MMU_SHIFT)
250               | (((int)(pte->pte) & (int)CF_PAGE_MMUTR_MASK ) >> CF_PAGE_MMUTR_SHIFT)
251               | MMUTR_V;
252
253        *MMUDR = (pte_val(*pte) & PAGE_MASK)
254           | ((pte->pte) & CF_PAGE_MMUDR_MASK)
255               | MMUDR_SZ8K | MMUDR_X;
256        
257    if ( dtlb )
258            *MMUOR = MMUOR_ACC | MMUOR_UAA;
259    else
260        *MMUOR = MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA;
261
262    asm("nop");
263
264#ifdef DEBUG
265    printk("cf_tlb_miss: va=%lx, pa=%lx\n", (mmuar & PAGE_MASK),
266          (pte_val(*pte) & PAGE_MASK));
267#endif
268    local_irq_restore(flags);
269        return (0);
270}
271
272
273/*
274 * Context Management
275 *
276 * Based on arch/ppc/mmu_context.c
277 */
278
279/*
280 * Initialize the context management system.
281 */
282void __init mmu_context_init(void)
283{
284    /*
285     * Some processors have too few contexts to reserve one for
286     * init_mm, and require using context 0 for a normal task.
287     * Other processors reserve the use of context zero for the kernel.
288     * This code assumes FIRST_CONTEXT < 32.
289     */
290    context_map[0] = (1 << FIRST_CONTEXT) - 1;
291    next_mmu_context = FIRST_CONTEXT;
292    atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
293}
294
295/*
296 * Steal a context from a task that has one at the moment.
297 * This is only used on 8xx and 4xx and we presently assume that
298 * they don't do SMP. If they do then thicfpgalloc.hs will have to check
299 * whether the MM we steal is in use.
300 * We also assume that this is only used on systems that don't
301 * use an MMU hash table - this is true for 8xx and 4xx.
302 * This isn't an LRU system, it just frees up each context in
303 * turn (sort-of pseudo-random replacement :). This would be the
304 * place to implement an LRU scheme if anyone was motivated to do it.
305 * -- paulus
306 */
307void steal_context(void)
308{
309    struct mm_struct *mm;
310    /* free up context `next_mmu_context' */
311    /* if we shouldn't free context 0, don't... */
312    if (next_mmu_context < FIRST_CONTEXT)
313        next_mmu_context = FIRST_CONTEXT;
314    mm = context_mm[next_mmu_context];
315    flush_tlb_mm(mm);
316    destroy_context(mm);
317}
318

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