arch/riscv/mm/ioremap.c

   1 /*
   2  * (C) Copyright 1995 1996 Linus Torvalds
   3  * (C) Copyright 2012 Regents of the University of California
   4  *
   5  *   This program is free software; you can redistribute it and/or
   6  *   modify it under the terms of the GNU General Public License
   7  *   as published by the Free Software Foundation, version 2.
   8  *
   9  *   This program is distributed in the hope that it will be useful,
  10  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *   GNU General Public License for more details.
  13  */
  14
  15 #include <linux/export.h>
  16 #include <linux/mm.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/io.h>
  19
  20 #include <asm/pgtable.h>
  21
  22 /*
  23  * Remap an arbitrary physical address space into the kernel virtual
  24  * address space. Needed when the kernel wants to access high addresses
  25  * directly.
  26  *
  27  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  28  * have to convert them into an offset in a page-aligned mapping, but the
  29  * caller shouldn't need to know that small detail.
  30  */
  31 static void __iomem *__ioremap_caller(phys_addr_t addr, size_t size,
  32         pgprot_t prot, void *caller)
  33 {
  34         phys_addr_t last_addr;
  35         unsigned long offset, vaddr;
  36         struct vm_struct *area;
  37
  38         /* Disallow wrap-around or zero size */
  39         last_addr = addr + size - 1;
  40         if (!size || last_addr < addr)
  41                 return NULL;
  42
  43         /* Page-align mappings */
  44         offset = addr & (~PAGE_MASK);
  45         addr &= PAGE_MASK;
  46         size = PAGE_ALIGN(size + offset);
  47
  48         area = get_vm_area_caller(size, VM_IOREMAP, caller);
  49         if (!area)
  50                 return NULL;
  51         vaddr = (unsigned long)area->addr;
  52
  53         if (ioremap_page_range(vaddr, vaddr + size, addr, prot)) {
  54                 free_vm_area(area);
  55                 return NULL;
  56         }
  57
  58         return (void __iomem *)(vaddr + offset);
  59 }
  60
  61 /*
  62  * ioremap     -   map bus memory into CPU space
  63  * @offset:    bus address of the memory
  64  * @size:      size of the resource to map
  65  *
  66  * ioremap performs a platform specific sequence of operations to
  67  * make bus memory CPU accessible via the readb/readw/readl/writeb/
  68  * writew/writel functions and the other mmio helpers. The returned
  69  * address is not guaranteed to be usable directly as a virtual
  70  * address.
  71  *
  72  * Must be freed with iounmap.
  73  */
  74 void __iomem *ioremap(phys_addr_t offset, unsigned long size)
  75 {
  76         return __ioremap_caller(offset, size, PAGE_KERNEL,
  77                 __builtin_return_address(0));
  78 }
  79 EXPORT_SYMBOL(ioremap);
  80
  81
  82 /**
  83  * iounmap - Free a IO remapping
  84  * @addr: virtual address from ioremap_*
  85  *
  86  * Caller must ensure there is only one unmapping for the same pointer.
  87  */
  88 void iounmap(volatile void __iomem *addr)
  89 {
  90         vunmap((void *)((unsigned long)addr & PAGE_MASK));
  91 }
  92 EXPORT_SYMBOL(iounmap);