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
  25 static 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
  41 static const struct file_operations fram_fops = {
  42         .owner                  = THIS_MODULE,
  43         .mmap                   = fram_mmap,
  44         .llseek                 = noop_llseek,
  45 };
  46
  47 #define FRAM_MINOR      0
  48
  49 static struct miscdevice fram_dev = {
  50         FRAM_MINOR,
  51         "fram",
  52         &fram_fops
  53 };
  54
  55 static int __init
  56 fram_init(void)
  57 {
  58         int ret;
  59
  60         ret = misc_register(&fram_dev);
  61         if (ret) {
  62                 printk(KERN_ERR "fram: can't misc_register on minor=%d\n",
  63                     FRAM_MINOR);
  64                 return ret;
  65         }
  66         printk(KERN_INFO "FRAM memory driver v" FRAM_VERSION "\n");
  67         return 0;
  68 }
  69
  70 static void __exit
  71 fram_cleanup_module(void)
  72 {
  73         misc_deregister(&fram_dev);
  74 }
  75
  76 module_init(fram_init);
  77 module_exit(fram_cleanup_module);
  78
  79 MODULE_LICENSE("GPL");
  80
  81 MODULE_ALIAS_MISCDEV(FRAM_MINOR);