LXR linux/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 */
  31static 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 */
  74void __iomem *ioremap(phys_addr_t offset, unsigned long size)
  75{
  76        return __ioremap_caller(offset, size, PAGE_KERNEL,
  77                __builtin_return_address(0));
  78}
  79EXPORT_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 */
  88void iounmap(volatile void __iomem *addr)
  89{
  90        vunmap((void *)((unsigned long)addr & PAGE_MASK));
  91}
  92EXPORT_SYMBOL(iounmap);
  93