arch/arc/mm/ioremap.c

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/vmalloc.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/io.h>
  13 #include <linux/mm.h>
  14 #include <linux/slab.h>
  15 #include <linux/cache.h>
  16
  17 static inline bool arc_uncached_addr_space(phys_addr_t paddr)
  18 {
  19         if (is_isa_arcompact()) {
  20                 if (paddr >= ARC_UNCACHED_ADDR_SPACE)
  21                         return true;
  22         } else if (paddr >= perip_base && paddr <= 0xFFFFFFFF) {
  23                 return true;
  24         }
  25
  26         return false;
  27 }
  28
  29 void __iomem *ioremap(phys_addr_t paddr, unsigned long size)
  30 {
  31         phys_addr_t end;
  32
  33         /* Don't allow wraparound or zero size */
  34         end = paddr + size - 1;
  35         if (!size || (end < paddr))
  36                 return NULL;
  37
  38         /*
  39          * If the region is h/w uncached, MMU mapping can be elided as optim
  40          * The cast to u32 is fine as this region can only be inside 4GB
  41          */
  42         if (arc_uncached_addr_space(paddr))
  43                 return (void __iomem *)(u32)paddr;
  44
  45         return ioremap_prot(paddr, size, PAGE_KERNEL_NO_CACHE);
  46 }
  47 EXPORT_SYMBOL(ioremap);
  48
  49 /*
  50  * ioremap with access flags
  51  * Cache semantics wise it is same as ioremap - "forced" uncached.
  52  * However unline vanilla ioremap which bypasses ARC MMU for addresses in
  53  * ARC hardware uncached region, this one still goes thru the MMU as caller
  54  * might need finer access control (R/W/X)
  55  */
  56 void __iomem *ioremap_prot(phys_addr_t paddr, unsigned long size,
  57                            unsigned long flags)
  58 {
  59         unsigned long vaddr;
  60         struct vm_struct *area;
  61         phys_addr_t off, end;
  62         pgprot_t prot = __pgprot(flags);
  63
  64         /* Don't allow wraparound, zero size */
  65         end = paddr + size - 1;
  66         if ((!size) || (end < paddr))
  67                 return NULL;
  68
  69         /* An early platform driver might end up here */
  70         if (!slab_is_available())
  71                 return NULL;
  72
  73         /* force uncached */
  74         prot = pgprot_noncached(prot);
  75
  76         /* Mappings have to be page-aligned */
  77         off = paddr & ~PAGE_MASK;
  78         paddr &= PAGE_MASK;
  79         size = PAGE_ALIGN(end + 1) - paddr;
  80
  81         /*
  82          * Ok, go for it..
  83          */
  84         area = get_vm_area(size, VM_IOREMAP);
  85         if (!area)
  86                 return NULL;
  87         area->phys_addr = paddr;
  88         vaddr = (unsigned long)area->addr;
  89         if (ioremap_page_range(vaddr, vaddr + size, paddr, prot)) {
  90                 vunmap((void __force *)vaddr);
  91                 return NULL;
  92         }
  93         return (void __iomem *)(off + (char __iomem *)vaddr);
  94 }
  95 EXPORT_SYMBOL(ioremap_prot);
  96
  97
  98 void iounmap(const void __iomem *addr)
  99 {
 100         /* weird double cast to handle phys_addr_t > 32 bits */
 101         if (arc_uncached_addr_space((phys_addr_t)(u32)addr))
 102                 return;
 103
 104         vfree((void *)(PAGE_MASK & (unsigned long __force)addr));
 105 }
 106 EXPORT_SYMBOL(iounmap);