LXR linux/arch/avr32/boards/mimc200/fram.c

   1/*
   2 * FRAM driver for MIMC200 board
   3 *
   4 * Copyright 2008 Mark Jackson <mpfj@mimc.co.uk>
   5 *
   6 * This module adds *very* simply support for the system's FRAM device.
   7 * At the moment, this is hard-coded to the MIMC200 platform, and only
   8 * supports mmap().
   9 */
  10
  11#define FRAM_VERSION    "1.0"
  12
  13#include <linux/miscdevice.h>
  14#include <linux/proc_fs.h>
  15#include <linux/mm.h>
  16#include <linux/io.h>
  17
  18#define FRAM_BASE       0xac000000
  19#define FRAM_SIZE       0x20000
  20
  21/*
  22 * The are the file operation function for user access to /dev/fram
  23 */
  24
  25static int fram_mmap(struct file *filp, struct vm_area_struct *vma)
  26{
  27        int ret;
  28
  29        ret = remap_pfn_range(vma,
  30                vma->vm_start,
  31                virt_to_phys((void *)((unsigned long)FRAM_BASE)) >> PAGE_SHIFT,
  32                vma->vm_end-vma->vm_start,
  33                PAGE_SHARED);
  34
  35        if (ret != 0)
  36                return -EAGAIN;
  37
  38        return 0;
  39}
  40
  41static const struct file_operations fram_fops = {
  42        .owner                  = THIS_MODULE,
  43        .mmap                   = fram_mmap,
  44};
  45
  46#define FRAM_MINOR      0
  47
  48static struct miscdevice fram_dev = {
  49        FRAM_MINOR,
  50        "fram",
  51        &fram_fops
  52};
  53
  54static int __init
  55fram_init(void)
  56{
  57        int ret;
  58
  59        ret = misc_register(&fram_dev);
  60        if (ret) {
  61                printk(KERN_ERR "fram: can't misc_register on minor=%d\n",
  62                    FRAM_MINOR);
  63                return ret;
  64        }
  65        printk(KERN_INFO "FRAM memory driver v" FRAM_VERSION "\n");
  66        return 0;
  67}
  68
  69static void __exit
  70fram_cleanup_module(void)
  71{
  72        misc_deregister(&fram_dev);
  73}
  74
  75module_init(fram_init);
  76module_exit(fram_cleanup_module);
  77
  78MODULE_LICENSE("GPL");
  79
  80MODULE_ALIAS_MISCDEV(FRAM_MINOR);
  81