arch/um/drivers/mmapper_kern.c

   1 /*
   2  * arch/um/drivers/mmapper_kern.c
   3  *
   4  * BRIEF MODULE DESCRIPTION
   5  *
   6  * Copyright (C) 2000 RidgeRun, Inc.
   7  * Author: RidgeRun, Inc.
   8  *         Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com
   9  *
  10  */
  11
  12 #include <linux/stddef.h>
  13 #include <linux/types.h>
  14 #include <linux/fs.h>
  15 #include <linux/init.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/module.h>
  18 #include <linux/mm.h>
  19
  20 #include <asm/uaccess.h>
  21 #include "mem_user.h"
  22
  23 /* These are set in mmapper_init, which is called at boot time */
  24 static unsigned long mmapper_size;
  25 static unsigned long p_buf;
  26 static char *v_buf;
  27
  28 static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count,
  29                             loff_t *ppos)
  30 {
  31         return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);
  32 }
  33
  34 static ssize_t mmapper_write(struct file *file, const char __user *buf,
  35                              size_t count, loff_t *ppos)
  36 {
  37         if (*ppos > mmapper_size)
  38                 return -EINVAL;
  39
  40         return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count);
  41 }
  42
  43 static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  44 {
  45         return -ENOIOCTLCMD;
  46 }
  47
  48 static int mmapper_mmap(struct file *file, struct vm_area_struct *vma)
  49 {
  50         int ret = -EINVAL;
  51         int size;
  52
  53         if (vma->vm_pgoff != 0)
  54                 goto out;
  55
  56         size = vma->vm_end - vma->vm_start;
  57         if (size > mmapper_size)
  58                 return -EFAULT;
  59
  60         /*
  61          * XXX A comment above remap_pfn_range says it should only be
  62          * called when the mm semaphore is held
  63          */
  64         if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size,
  65                             vma->vm_page_prot))
  66                 goto out;
  67         ret = 0;
  68 out:
  69         return ret;
  70 }
  71
  72 static int mmapper_open(struct inode *inode, struct file *file)
  73 {
  74         return 0;
  75 }
  76
  77 static int mmapper_release(struct inode *inode, struct file *file)
  78 {
  79         return 0;
  80 }
  81
  82 static const struct file_operations mmapper_fops = {
  83         .owner          = THIS_MODULE,
  84         .read           = mmapper_read,
  85         .write          = mmapper_write,
  86         .unlocked_ioctl = mmapper_ioctl,
  87         .mmap           = mmapper_mmap,
  88         .open           = mmapper_open,
  89         .release        = mmapper_release,
  90         .llseek         = default_llseek,
  91 };
  92
  93 /*
  94  * No locking needed - only used (and modified) by below initcall and exitcall.
  95  */
  96 static struct miscdevice mmapper_dev = {
  97         .minor          = MISC_DYNAMIC_MINOR,
  98         .name           = "mmapper",
  99         .fops           = &mmapper_fops
 100 };
 101
 102 static int __init mmapper_init(void)
 103 {
 104         int err;
 105
 106         printk(KERN_INFO "Mapper v0.1\n");
 107
 108         v_buf = (char *) find_iomem("mmapper", &mmapper_size);
 109         if (mmapper_size == 0) {
 110                 printk(KERN_ERR "mmapper_init - find_iomem failed\n");
 111                 return -ENODEV;
 112         }
 113         p_buf = __pa(v_buf);
 114
 115         err = misc_register(&mmapper_dev);
 116         if (err) {
 117                 printk(KERN_ERR "mmapper - misc_register failed, err = %d\n",
 118                        err);
 119                 return err;;
 120         }
 121         return 0;
 122 }
 123
 124 static void mmapper_exit(void)
 125 {
 126         misc_deregister(&mmapper_dev);
 127 }
 128
 129 module_init(mmapper_init);
 130 module_exit(mmapper_exit);
 131
 132 MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
 133 MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");
 134 MODULE_LICENSE("GPL");