fram.c

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/*
 * FRAM driver for MIMC200 board
 *
 * Copyright 2008 Mark Jackson <[email protected]>
 *
 * 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);