xref: /openbmc/linux/arch/x86/mm/ioremap.c (revision b34e08d5)
1 /*
2  * Re-map IO memory to kernel address space so that we can access it.
3  * This is needed for high PCI addresses that aren't mapped in the
4  * 640k-1MB IO memory area on PC's
5  *
6  * (C) Copyright 1995 1996 Linus Torvalds
7  */
8 
9 #include <linux/bootmem.h>
10 #include <linux/init.h>
11 #include <linux/io.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/vmalloc.h>
15 #include <linux/mmiotrace.h>
16 
17 #include <asm/cacheflush.h>
18 #include <asm/e820.h>
19 #include <asm/fixmap.h>
20 #include <asm/pgtable.h>
21 #include <asm/tlbflush.h>
22 #include <asm/pgalloc.h>
23 #include <asm/pat.h>
24 
25 #include "physaddr.h"
26 
27 /*
28  * Fix up the linear direct mapping of the kernel to avoid cache attribute
29  * conflicts.
30  */
31 int ioremap_change_attr(unsigned long vaddr, unsigned long size,
32 			       unsigned long prot_val)
33 {
34 	unsigned long nrpages = size >> PAGE_SHIFT;
35 	int err;
36 
37 	switch (prot_val) {
38 	case _PAGE_CACHE_UC:
39 	default:
40 		err = _set_memory_uc(vaddr, nrpages);
41 		break;
42 	case _PAGE_CACHE_WC:
43 		err = _set_memory_wc(vaddr, nrpages);
44 		break;
45 	case _PAGE_CACHE_WB:
46 		err = _set_memory_wb(vaddr, nrpages);
47 		break;
48 	}
49 
50 	return err;
51 }
52 
53 /*
54  * Remap an arbitrary physical address space into the kernel virtual
55  * address space. Needed when the kernel wants to access high addresses
56  * directly.
57  *
58  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
59  * have to convert them into an offset in a page-aligned mapping, but the
60  * caller shouldn't need to know that small detail.
61  */
62 static void __iomem *__ioremap_caller(resource_size_t phys_addr,
63 		unsigned long size, unsigned long prot_val, void *caller)
64 {
65 	unsigned long offset, vaddr;
66 	resource_size_t pfn, last_pfn, last_addr;
67 	const resource_size_t unaligned_phys_addr = phys_addr;
68 	const unsigned long unaligned_size = size;
69 	struct vm_struct *area;
70 	unsigned long new_prot_val;
71 	pgprot_t prot;
72 	int retval;
73 	void __iomem *ret_addr;
74 
75 	/* Don't allow wraparound or zero size */
76 	last_addr = phys_addr + size - 1;
77 	if (!size || last_addr < phys_addr)
78 		return NULL;
79 
80 	if (!phys_addr_valid(phys_addr)) {
81 		printk(KERN_WARNING "ioremap: invalid physical address %llx\n",
82 		       (unsigned long long)phys_addr);
83 		WARN_ON_ONCE(1);
84 		return NULL;
85 	}
86 
87 	/*
88 	 * Don't remap the low PCI/ISA area, it's always mapped..
89 	 */
90 	if (is_ISA_range(phys_addr, last_addr))
91 		return (__force void __iomem *)phys_to_virt(phys_addr);
92 
93 	/*
94 	 * Don't allow anybody to remap normal RAM that we're using..
95 	 */
96 	last_pfn = last_addr >> PAGE_SHIFT;
97 	for (pfn = phys_addr >> PAGE_SHIFT; pfn <= last_pfn; pfn++) {
98 		int is_ram = page_is_ram(pfn);
99 
100 		if (is_ram && pfn_valid(pfn) && !PageReserved(pfn_to_page(pfn)))
101 			return NULL;
102 		WARN_ON_ONCE(is_ram);
103 	}
104 
105 	/*
106 	 * Mappings have to be page-aligned
107 	 */
108 	offset = phys_addr & ~PAGE_MASK;
109 	phys_addr &= PHYSICAL_PAGE_MASK;
110 	size = PAGE_ALIGN(last_addr+1) - phys_addr;
111 
112 	retval = reserve_memtype(phys_addr, (u64)phys_addr + size,
113 						prot_val, &new_prot_val);
114 	if (retval) {
115 		printk(KERN_ERR "ioremap reserve_memtype failed %d\n", retval);
116 		return NULL;
117 	}
118 
119 	if (prot_val != new_prot_val) {
120 		if (!is_new_memtype_allowed(phys_addr, size,
121 					    prot_val, new_prot_val)) {
122 			printk(KERN_ERR
123 		"ioremap error for 0x%llx-0x%llx, requested 0x%lx, got 0x%lx\n",
124 				(unsigned long long)phys_addr,
125 				(unsigned long long)(phys_addr + size),
126 				prot_val, new_prot_val);
127 			goto err_free_memtype;
128 		}
129 		prot_val = new_prot_val;
130 	}
131 
132 	switch (prot_val) {
133 	case _PAGE_CACHE_UC:
134 	default:
135 		prot = PAGE_KERNEL_IO_NOCACHE;
136 		break;
137 	case _PAGE_CACHE_UC_MINUS:
138 		prot = PAGE_KERNEL_IO_UC_MINUS;
139 		break;
140 	case _PAGE_CACHE_WC:
141 		prot = PAGE_KERNEL_IO_WC;
142 		break;
143 	case _PAGE_CACHE_WB:
144 		prot = PAGE_KERNEL_IO;
145 		break;
146 	}
147 
148 	/*
149 	 * Ok, go for it..
150 	 */
151 	area = get_vm_area_caller(size, VM_IOREMAP, caller);
152 	if (!area)
153 		goto err_free_memtype;
154 	area->phys_addr = phys_addr;
155 	vaddr = (unsigned long) area->addr;
156 
157 	if (kernel_map_sync_memtype(phys_addr, size, prot_val))
158 		goto err_free_area;
159 
160 	if (ioremap_page_range(vaddr, vaddr + size, phys_addr, prot))
161 		goto err_free_area;
162 
163 	ret_addr = (void __iomem *) (vaddr + offset);
164 	mmiotrace_ioremap(unaligned_phys_addr, unaligned_size, ret_addr);
165 
166 	/*
167 	 * Check if the request spans more than any BAR in the iomem resource
168 	 * tree.
169 	 */
170 	WARN_ONCE(iomem_map_sanity_check(unaligned_phys_addr, unaligned_size),
171 		  KERN_INFO "Info: mapping multiple BARs. Your kernel is fine.");
172 
173 	return ret_addr;
174 err_free_area:
175 	free_vm_area(area);
176 err_free_memtype:
177 	free_memtype(phys_addr, phys_addr + size);
178 	return NULL;
179 }
180 
181 /**
182  * ioremap_nocache     -   map bus memory into CPU space
183  * @phys_addr:    bus address of the memory
184  * @size:      size of the resource to map
185  *
186  * ioremap_nocache performs a platform specific sequence of operations to
187  * make bus memory CPU accessible via the readb/readw/readl/writeb/
188  * writew/writel functions and the other mmio helpers. The returned
189  * address is not guaranteed to be usable directly as a virtual
190  * address.
191  *
192  * This version of ioremap ensures that the memory is marked uncachable
193  * on the CPU as well as honouring existing caching rules from things like
194  * the PCI bus. Note that there are other caches and buffers on many
195  * busses. In particular driver authors should read up on PCI writes
196  *
197  * It's useful if some control registers are in such an area and
198  * write combining or read caching is not desirable:
199  *
200  * Must be freed with iounmap.
201  */
202 void __iomem *ioremap_nocache(resource_size_t phys_addr, unsigned long size)
203 {
204 	/*
205 	 * Ideally, this should be:
206 	 *	pat_enabled ? _PAGE_CACHE_UC : _PAGE_CACHE_UC_MINUS;
207 	 *
208 	 * Till we fix all X drivers to use ioremap_wc(), we will use
209 	 * UC MINUS.
210 	 */
211 	unsigned long val = _PAGE_CACHE_UC_MINUS;
212 
213 	return __ioremap_caller(phys_addr, size, val,
214 				__builtin_return_address(0));
215 }
216 EXPORT_SYMBOL(ioremap_nocache);
217 
218 /**
219  * ioremap_wc	-	map memory into CPU space write combined
220  * @phys_addr:	bus address of the memory
221  * @size:	size of the resource to map
222  *
223  * This version of ioremap ensures that the memory is marked write combining.
224  * Write combining allows faster writes to some hardware devices.
225  *
226  * Must be freed with iounmap.
227  */
228 void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
229 {
230 	if (pat_enabled)
231 		return __ioremap_caller(phys_addr, size, _PAGE_CACHE_WC,
232 					__builtin_return_address(0));
233 	else
234 		return ioremap_nocache(phys_addr, size);
235 }
236 EXPORT_SYMBOL(ioremap_wc);
237 
238 void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
239 {
240 	return __ioremap_caller(phys_addr, size, _PAGE_CACHE_WB,
241 				__builtin_return_address(0));
242 }
243 EXPORT_SYMBOL(ioremap_cache);
244 
245 void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size,
246 				unsigned long prot_val)
247 {
248 	return __ioremap_caller(phys_addr, size, (prot_val & _PAGE_CACHE_MASK),
249 				__builtin_return_address(0));
250 }
251 EXPORT_SYMBOL(ioremap_prot);
252 
253 /**
254  * iounmap - Free a IO remapping
255  * @addr: virtual address from ioremap_*
256  *
257  * Caller must ensure there is only one unmapping for the same pointer.
258  */
259 void iounmap(volatile void __iomem *addr)
260 {
261 	struct vm_struct *p, *o;
262 
263 	if ((void __force *)addr <= high_memory)
264 		return;
265 
266 	/*
267 	 * __ioremap special-cases the PCI/ISA range by not instantiating a
268 	 * vm_area and by simply returning an address into the kernel mapping
269 	 * of ISA space.   So handle that here.
270 	 */
271 	if ((void __force *)addr >= phys_to_virt(ISA_START_ADDRESS) &&
272 	    (void __force *)addr < phys_to_virt(ISA_END_ADDRESS))
273 		return;
274 
275 	addr = (volatile void __iomem *)
276 		(PAGE_MASK & (unsigned long __force)addr);
277 
278 	mmiotrace_iounmap(addr);
279 
280 	/* Use the vm area unlocked, assuming the caller
281 	   ensures there isn't another iounmap for the same address
282 	   in parallel. Reuse of the virtual address is prevented by
283 	   leaving it in the global lists until we're done with it.
284 	   cpa takes care of the direct mappings. */
285 	p = find_vm_area((void __force *)addr);
286 
287 	if (!p) {
288 		printk(KERN_ERR "iounmap: bad address %p\n", addr);
289 		dump_stack();
290 		return;
291 	}
292 
293 	free_memtype(p->phys_addr, p->phys_addr + get_vm_area_size(p));
294 
295 	/* Finally remove it */
296 	o = remove_vm_area((void __force *)addr);
297 	BUG_ON(p != o || o == NULL);
298 	kfree(p);
299 }
300 EXPORT_SYMBOL(iounmap);
301 
302 /*
303  * Convert a physical pointer to a virtual kernel pointer for /dev/mem
304  * access
305  */
306 void *xlate_dev_mem_ptr(unsigned long phys)
307 {
308 	void *addr;
309 	unsigned long start = phys & PAGE_MASK;
310 
311 	/* If page is RAM, we can use __va. Otherwise ioremap and unmap. */
312 	if (page_is_ram(start >> PAGE_SHIFT))
313 		return __va(phys);
314 
315 	addr = (void __force *)ioremap_cache(start, PAGE_SIZE);
316 	if (addr)
317 		addr = (void *)((unsigned long)addr | (phys & ~PAGE_MASK));
318 
319 	return addr;
320 }
321 
322 void unxlate_dev_mem_ptr(unsigned long phys, void *addr)
323 {
324 	if (page_is_ram(phys >> PAGE_SHIFT))
325 		return;
326 
327 	iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK));
328 	return;
329 }
330 
331 static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;
332 
333 static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
334 {
335 	/* Don't assume we're using swapper_pg_dir at this point */
336 	pgd_t *base = __va(read_cr3());
337 	pgd_t *pgd = &base[pgd_index(addr)];
338 	pud_t *pud = pud_offset(pgd, addr);
339 	pmd_t *pmd = pmd_offset(pud, addr);
340 
341 	return pmd;
342 }
343 
344 static inline pte_t * __init early_ioremap_pte(unsigned long addr)
345 {
346 	return &bm_pte[pte_index(addr)];
347 }
348 
349 bool __init is_early_ioremap_ptep(pte_t *ptep)
350 {
351 	return ptep >= &bm_pte[0] && ptep < &bm_pte[PAGE_SIZE/sizeof(pte_t)];
352 }
353 
354 void __init early_ioremap_init(void)
355 {
356 	pmd_t *pmd;
357 
358 	early_ioremap_setup();
359 
360 	pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
361 	memset(bm_pte, 0, sizeof(bm_pte));
362 	pmd_populate_kernel(&init_mm, pmd, bm_pte);
363 
364 	/*
365 	 * The boot-ioremap range spans multiple pmds, for which
366 	 * we are not prepared:
367 	 */
368 #define __FIXADDR_TOP (-PAGE_SIZE)
369 	BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
370 		     != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
371 #undef __FIXADDR_TOP
372 	if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
373 		WARN_ON(1);
374 		printk(KERN_WARNING "pmd %p != %p\n",
375 		       pmd, early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END)));
376 		printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
377 			fix_to_virt(FIX_BTMAP_BEGIN));
378 		printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_END):   %08lx\n",
379 			fix_to_virt(FIX_BTMAP_END));
380 
381 		printk(KERN_WARNING "FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
382 		printk(KERN_WARNING "FIX_BTMAP_BEGIN:     %d\n",
383 		       FIX_BTMAP_BEGIN);
384 	}
385 }
386 
387 void __init __early_set_fixmap(enum fixed_addresses idx,
388 			       phys_addr_t phys, pgprot_t flags)
389 {
390 	unsigned long addr = __fix_to_virt(idx);
391 	pte_t *pte;
392 
393 	if (idx >= __end_of_fixed_addresses) {
394 		BUG();
395 		return;
396 	}
397 	pte = early_ioremap_pte(addr);
398 
399 	if (pgprot_val(flags))
400 		set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags));
401 	else
402 		pte_clear(&init_mm, addr, pte);
403 	__flush_tlb_one(addr);
404 }
405