xref: /openbmc/linux/arch/microblaze/mm/pgtable.c (revision d6fc9fcb)
1 /*
2  *  This file contains the routines setting up the linux page tables.
3  *
4  * Copyright (C) 2008 Michal Simek
5  * Copyright (C) 2008 PetaLogix
6  *
7  *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
8  *
9  *  Derived from arch/ppc/mm/pgtable.c:
10  *    -- paulus
11  *
12  *  Derived from arch/ppc/mm/init.c:
13  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
14  *
15  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
16  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
17  *    Copyright (C) 1996 Paul Mackerras
18  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
19  *
20  *  Derived from "arch/i386/mm/init.c"
21  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
22  *
23  *  This file is subject to the terms and conditions of the GNU General
24  *  Public License.  See the file COPYING in the main directory of this
25  *  archive for more details.
26  *
27  */
28 
29 #include <linux/export.h>
30 #include <linux/kernel.h>
31 #include <linux/types.h>
32 #include <linux/vmalloc.h>
33 #include <linux/init.h>
34 #include <linux/mm_types.h>
35 
36 #include <asm/pgtable.h>
37 #include <asm/pgalloc.h>
38 #include <linux/io.h>
39 #include <asm/mmu.h>
40 #include <asm/sections.h>
41 #include <asm/fixmap.h>
42 
43 unsigned long ioremap_base;
44 unsigned long ioremap_bot;
45 EXPORT_SYMBOL(ioremap_bot);
46 
47 #ifndef CONFIG_SMP
48 struct pgtable_cache_struct quicklists;
49 #endif
50 
51 static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
52 		unsigned long flags)
53 {
54 	unsigned long v, i;
55 	phys_addr_t p;
56 	int err;
57 
58 	/*
59 	 * Choose an address to map it to.
60 	 * Once the vmalloc system is running, we use it.
61 	 * Before then, we use space going down from ioremap_base
62 	 * (ioremap_bot records where we're up to).
63 	 */
64 	p = addr & PAGE_MASK;
65 	size = PAGE_ALIGN(addr + size) - p;
66 
67 	/*
68 	 * Don't allow anybody to remap normal RAM that we're using.
69 	 * mem_init() sets high_memory so only do the check after that.
70 	 *
71 	 * However, allow remap of rootfs: TBD
72 	 */
73 
74 	if (mem_init_done &&
75 		p >= memory_start && p < virt_to_phys(high_memory) &&
76 		!(p >= __virt_to_phys((phys_addr_t)__bss_stop) &&
77 		p < __virt_to_phys((phys_addr_t)__bss_stop))) {
78 		pr_warn("__ioremap(): phys addr "PTE_FMT" is RAM lr %ps\n",
79 			(unsigned long)p, __builtin_return_address(0));
80 		return NULL;
81 	}
82 
83 	if (size == 0)
84 		return NULL;
85 
86 	/*
87 	 * Is it already mapped? If the whole area is mapped then we're
88 	 * done, otherwise remap it since we want to keep the virt addrs for
89 	 * each request contiguous.
90 	 *
91 	 * We make the assumption here that if the bottom and top
92 	 * of the range we want are mapped then it's mapped to the
93 	 * same virt address (and this is contiguous).
94 	 *  -- Cort
95 	 */
96 
97 	if (mem_init_done) {
98 		struct vm_struct *area;
99 		area = get_vm_area(size, VM_IOREMAP);
100 		if (area == NULL)
101 			return NULL;
102 		v = (unsigned long) area->addr;
103 	} else {
104 		v = (ioremap_bot -= size);
105 	}
106 
107 	if ((flags & _PAGE_PRESENT) == 0)
108 		flags |= _PAGE_KERNEL;
109 	if (flags & _PAGE_NO_CACHE)
110 		flags |= _PAGE_GUARDED;
111 
112 	err = 0;
113 	for (i = 0; i < size && err == 0; i += PAGE_SIZE)
114 		err = map_page(v + i, p + i, flags);
115 	if (err) {
116 		if (mem_init_done)
117 			vfree((void *)v);
118 		return NULL;
119 	}
120 
121 	return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
122 }
123 
124 void __iomem *ioremap(phys_addr_t addr, unsigned long size)
125 {
126 	return __ioremap(addr, size, _PAGE_NO_CACHE);
127 }
128 EXPORT_SYMBOL(ioremap);
129 
130 void iounmap(volatile void __iomem *addr)
131 {
132 	if ((__force void *)addr > high_memory &&
133 					(unsigned long) addr < ioremap_bot)
134 		vfree((void *) (PAGE_MASK & (unsigned long) addr));
135 }
136 EXPORT_SYMBOL(iounmap);
137 
138 
139 int map_page(unsigned long va, phys_addr_t pa, int flags)
140 {
141 	pmd_t *pd;
142 	pte_t *pg;
143 	int err = -ENOMEM;
144 	/* Use upper 10 bits of VA to index the first level map */
145 	pd = pmd_offset(pgd_offset_k(va), va);
146 	/* Use middle 10 bits of VA to index the second-level map */
147 	pg = pte_alloc_kernel(pd, va); /* from powerpc - pgtable.c */
148 	/* pg = pte_alloc_kernel(&init_mm, pd, va); */
149 
150 	if (pg != NULL) {
151 		err = 0;
152 		set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
153 				__pgprot(flags)));
154 		if (unlikely(mem_init_done))
155 			_tlbie(va);
156 	}
157 	return err;
158 }
159 
160 /*
161  * Map in all of physical memory starting at CONFIG_KERNEL_START.
162  */
163 void __init mapin_ram(void)
164 {
165 	unsigned long v, p, s, f;
166 
167 	v = CONFIG_KERNEL_START;
168 	p = memory_start;
169 	for (s = 0; s < lowmem_size; s += PAGE_SIZE) {
170 		f = _PAGE_PRESENT | _PAGE_ACCESSED |
171 				_PAGE_SHARED | _PAGE_HWEXEC;
172 		if ((char *) v < _stext || (char *) v >= _etext)
173 			f |= _PAGE_WRENABLE;
174 		else
175 			/* On the MicroBlaze, no user access
176 			   forces R/W kernel access */
177 			f |= _PAGE_USER;
178 		map_page(v, p, f);
179 		v += PAGE_SIZE;
180 		p += PAGE_SIZE;
181 	}
182 }
183 
184 /* is x a power of 2? */
185 #define is_power_of_2(x)	((x) != 0 && (((x) & ((x) - 1)) == 0))
186 
187 /* Scan the real Linux page tables and return a PTE pointer for
188  * a virtual address in a context.
189  * Returns true (1) if PTE was found, zero otherwise.  The pointer to
190  * the PTE pointer is unmodified if PTE is not found.
191  */
192 static int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
193 {
194 	pgd_t	*pgd;
195 	pmd_t	*pmd;
196 	pte_t	*pte;
197 	int     retval = 0;
198 
199 	pgd = pgd_offset(mm, addr & PAGE_MASK);
200 	if (pgd) {
201 		pmd = pmd_offset(pgd, addr & PAGE_MASK);
202 		if (pmd_present(*pmd)) {
203 			pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
204 			if (pte) {
205 				retval = 1;
206 				*ptep = pte;
207 			}
208 		}
209 	}
210 	return retval;
211 }
212 
213 /* Find physical address for this virtual address.  Normally used by
214  * I/O functions, but anyone can call it.
215  */
216 unsigned long iopa(unsigned long addr)
217 {
218 	unsigned long pa;
219 
220 	pte_t *pte;
221 	struct mm_struct *mm;
222 
223 	/* Allow mapping of user addresses (within the thread)
224 	 * for DMA if necessary.
225 	 */
226 	if (addr < TASK_SIZE)
227 		mm = current->mm;
228 	else
229 		mm = &init_mm;
230 
231 	pa = 0;
232 	if (get_pteptr(mm, addr, &pte))
233 		pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
234 
235 	return pa;
236 }
237 
238 __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
239 {
240 	pte_t *pte;
241 	if (mem_init_done) {
242 		pte = (pte_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
243 	} else {
244 		pte = (pte_t *)early_get_page();
245 		if (pte)
246 			clear_page(pte);
247 	}
248 	return pte;
249 }
250 
251 void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags)
252 {
253 	unsigned long address = __fix_to_virt(idx);
254 
255 	if (idx >= __end_of_fixed_addresses)
256 		BUG();
257 
258 	map_page(address, phys, pgprot_val(flags));
259 }
260