mm/early_ioremap.c

   1 /*
   2  * Provide common bits of early_ioremap() support for architectures needing
   3  * temporary mappings during boot before ioremap() is available.
   4  *
   5  * This is mostly a direct copy of the x86 early_ioremap implementation.
   6  *
   7  * (C) Copyright 1995 1996, 2014 Linus Torvalds
   8  *
   9  */
  10 #include <linux/kernel.h>
  11 #include <linux/init.h>
  12 #include <linux/io.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/mm.h>
  16 #include <linux/vmalloc.h>
  17 #include <asm/fixmap.h>
  18
  19 #ifdef CONFIG_MMU
  20 static int early_ioremap_debug __initdata;
  21
  22 static int __init early_ioremap_debug_setup(char *str)
  23 {
  24         early_ioremap_debug = 1;
  25
  26         return 0;
  27 }
  28 early_param("early_ioremap_debug", early_ioremap_debug_setup);
  29
  30 static int after_paging_init __initdata;
  31
  32 void __init __weak early_ioremap_shutdown(void)
  33 {
  34 }
  35
  36 void __init early_ioremap_reset(void)
  37 {
  38         early_ioremap_shutdown();
  39         after_paging_init = 1;
  40 }
  41
  42 /*
  43  * Generally, ioremap() is available after paging_init() has been called.
  44  * Architectures wanting to allow early_ioremap after paging_init() can
  45  * define __late_set_fixmap and __late_clear_fixmap to do the right thing.
  46  */
  47 #ifndef __late_set_fixmap
  48 static inline void __init __late_set_fixmap(enum fixed_addresses idx,
  49                                             phys_addr_t phys, pgprot_t prot)
  50 {
  51         BUG();
  52 }
  53 #endif
  54
  55 #ifndef __late_clear_fixmap
  56 static inline void __init __late_clear_fixmap(enum fixed_addresses idx)
  57 {
  58         BUG();
  59 }
  60 #endif
  61
  62 static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
  63 static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
  64 static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;
  65
  66 void __init early_ioremap_setup(void)
  67 {
  68         int i;
  69
  70         for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
  71                 if (WARN_ON(prev_map[i]))
  72                         break;
  73
  74         for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
  75                 slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*i);
  76 }
  77
  78 static int __init check_early_ioremap_leak(void)
  79 {
  80         int count = 0;
  81         int i;
  82
  83         for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
  84                 if (prev_map[i])
  85                         count++;
  86
  87         if (WARN(count, KERN_WARNING
  88                  "Debug warning: early ioremap leak of %d areas detected.\n"
  89                  "please boot with early_ioremap_debug and report the dmesg.\n",
  90                  count))
  91                 return 1;
  92         return 0;
  93 }
  94 late_initcall(check_early_ioremap_leak);
  95
  96 static void __init __iomem *
  97 __early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
  98 {
  99         unsigned long offset;
 100         resource_size_t last_addr;
 101         unsigned int nrpages;
 102         enum fixed_addresses idx;
 103         int i, slot;
 104
 105         WARN_ON(system_state != SYSTEM_BOOTING);
 106
 107         slot = -1;
 108         for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
 109                 if (!prev_map[i]) {
 110                         slot = i;
 111                         break;
 112                 }
 113         }
 114
 115         if (WARN(slot < 0, "%s(%08llx, %08lx) not found slot\n",
 116                  __func__, (u64)phys_addr, size))
 117                 return NULL;
 118
 119         /* Don't allow wraparound or zero size */
 120         last_addr = phys_addr + size - 1;
 121         if (WARN_ON(!size || last_addr < phys_addr))
 122                 return NULL;
 123
 124         prev_size[slot] = size;
 125         /*
 126          * Mappings have to be page-aligned
 127          */
 128         offset = phys_addr & ~PAGE_MASK;
 129         phys_addr &= PAGE_MASK;
 130         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 131
 132         /*
 133          * Mappings have to fit in the FIX_BTMAP area.
 134          */
 135         nrpages = size >> PAGE_SHIFT;
 136         if (WARN_ON(nrpages > NR_FIX_BTMAPS))
 137                 return NULL;
 138
 139         /*
 140          * Ok, go for it..
 141          */
 142         idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
 143         while (nrpages > 0) {
 144                 if (after_paging_init)
 145                         __late_set_fixmap(idx, phys_addr, prot);
 146                 else
 147                         __early_set_fixmap(idx, phys_addr, prot);
 148                 phys_addr += PAGE_SIZE;
 149                 --idx;
 150                 --nrpages;
 151         }
 152         WARN(early_ioremap_debug, "%s(%08llx, %08lx) [%d] => %08lx + %08lx\n",
 153              __func__, (u64)phys_addr, size, slot, offset, slot_virt[slot]);
 154
 155         prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
 156         return prev_map[slot];
 157 }
 158
 159 void __init early_iounmap(void __iomem *addr, unsigned long size)
 160 {
 161         unsigned long virt_addr;
 162         unsigned long offset;
 163         unsigned int nrpages;
 164         enum fixed_addresses idx;
 165         int i, slot;
 166
 167         slot = -1;
 168         for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
 169                 if (prev_map[i] == addr) {
 170                         slot = i;
 171                         break;
 172                 }
 173         }
 174
 175         if (WARN(slot < 0, "early_iounmap(%p, %08lx) not found slot\n",
 176                  addr, size))
 177                 return;
 178
 179         if (WARN(prev_size[slot] != size,
 180                  "early_iounmap(%p, %08lx) [%d] size not consistent %08lx\n",
 181                  addr, size, slot, prev_size[slot]))
 182                 return;
 183
 184         WARN(early_ioremap_debug, "early_iounmap(%p, %08lx) [%d]\n",
 185              addr, size, slot);
 186
 187         virt_addr = (unsigned long)addr;
 188         if (WARN_ON(virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)))
 189                 return;
 190
 191         offset = virt_addr & ~PAGE_MASK;
 192         nrpages = PAGE_ALIGN(offset + size) >> PAGE_SHIFT;
 193
 194         idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
 195         while (nrpages > 0) {
 196                 if (after_paging_init)
 197                         __late_clear_fixmap(idx);
 198                 else
 199                         __early_set_fixmap(idx, 0, FIXMAP_PAGE_CLEAR);
 200                 --idx;
 201                 --nrpages;
 202         }
 203         prev_map[slot] = NULL;
 204 }
 205
 206 /* Remap an IO device */
 207 void __init __iomem *
 208 early_ioremap(resource_size_t phys_addr, unsigned long size)
 209 {
 210         return __early_ioremap(phys_addr, size, FIXMAP_PAGE_IO);
 211 }
 212
 213 /* Remap memory */
 214 void __init *
 215 early_memremap(resource_size_t phys_addr, unsigned long size)
 216 {
 217         return (__force void *)__early_ioremap(phys_addr, size,
 218                                                FIXMAP_PAGE_NORMAL);
 219 }
 220 #else /* CONFIG_MMU */
 221
 222 void __init __iomem *
 223 early_ioremap(resource_size_t phys_addr, unsigned long size)
 224 {
 225         return (__force void __iomem *)phys_addr;
 226 }
 227
 228 /* Remap memory */
 229 void __init *
 230 early_memremap(resource_size_t phys_addr, unsigned long size)
 231 {
 232         return (void *)phys_addr;
 233 }
 234
 235 void __init early_iounmap(void __iomem *addr, unsigned long size)
 236 {
 237 }
 238
 239 #endif /* CONFIG_MMU */
 240
 241
 242 void __init early_memunmap(void *addr, unsigned long size)
 243 {
 244         early_iounmap((__force void __iomem *)addr, size);
 245 }