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fram.c

/*
 * FRAM driver for MIMC200 board
 *
 * Copyright 2008 Mark Jackson <mpfj@mimc.co.uk>
 *
 * This module adds *very* simply support for the system's FRAM device.
 * At the moment, this is hard-coded to the MIMC200 platform, and only
 * supports mmap().
 */

#define FRAM_VERSION    "1.0"

#include <linux/miscdevice.h>
#include <linux/proc_fs.h>
#include <linux/mm.h>
#include <linux/io.h>

#define FRAM_BASE 0xac000000
#define FRAM_SIZE 0x20000

/*
 * The are the file operation function for user access to /dev/fram
 */

static int fram_mmap(struct file *filp, struct vm_area_struct *vma)
{
      int ret;

      ret = remap_pfn_range(vma,
            vma->vm_start,
            virt_to_phys((void *)((unsigned long)FRAM_BASE)) >> PAGE_SHIFT,
            vma->vm_end-vma->vm_start,
            PAGE_SHARED);

      if (ret != 0)
            return -EAGAIN;

      return 0;
}

static const struct file_operations fram_fops = {
      .owner                  = THIS_MODULE,
      .mmap             = fram_mmap,
      .llseek                 = noop_llseek,
};

#define FRAM_MINOR      0

static struct miscdevice fram_dev = {
      FRAM_MINOR,
      "fram",
      &fram_fops
};

static int __init
fram_init(void)
{
      int ret;

      ret = misc_register(&fram_dev);
      if (ret) {
            printk(KERN_ERR "fram: can't misc_register on minor=%d\n",
                FRAM_MINOR);
            return ret;
      }
      printk(KERN_INFO "FRAM memory driver v" FRAM_VERSION "\n");
      return 0;
}

static void __exit
fram_cleanup_module(void)
{
      misc_deregister(&fram_dev);
}

module_init(fram_init);
module_exit(fram_cleanup_module);

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(FRAM_MINOR);

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