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 #include <asm/uaccess.h>
  20 #include "mem_user.h"
  21
  22 /* These are set in mmapper_init, which is called at boot time */
  23 static unsigned long mmapper_size;
  24 static unsigned long p_buf;
  25 static char *v_buf;
  26
  27 static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count,
  28                             loff_t *ppos)
  29 {
  30         return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);
  31 }
  32
  33 static ssize_t mmapper_write(struct file *file, const char __user *buf,
  34                              size_t count, loff_t *ppos)
  35 {
  36         if (*ppos > mmapper_size)
  37                 return -EINVAL;
  38
  39         if (count > mmapper_size - *ppos)
  40                 count = mmapper_size - *ppos;
  41
  42         if (copy_from_user(&v_buf[*ppos], buf, count))
  43                 return -EFAULT;
  44
  45         return count;
  46 }
  47
  48 static int mmapper_ioctl(struct inode *inode, struct file *file,
  49                          unsigned int cmd, unsigned long arg)
  50 {
  51         return -ENOIOCTLCMD;
  52 }
  53
  54 static int mmapper_mmap(struct file *file, struct vm_area_struct *vma)
  55 {
  56         int ret = -EINVAL;
  57         int size;
  58
  59         if (vma->vm_pgoff != 0)
  60                 goto out;
  61
  62         size = vma->vm_end - vma->vm_start;
  63         if (size > mmapper_size)
  64                 return -EFAULT;
  65
  66         /*
  67          * XXX A comment above remap_pfn_range says it should only be
  68          * called when the mm semaphore is held
  69          */
  70         if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size,
  71                             vma->vm_page_prot))
  72                 goto out;
  73         ret = 0;
  74 out:
  75         return ret;
  76 }
  77
  78 static int mmapper_open(struct inode *inode, struct file *file)
  79 {
  80         return 0;
  81 }
  82
  83 static int mmapper_release(struct inode *inode, struct file *file)
  84 {
  85         return 0;
  86 }
  87
  88 static const struct file_operations mmapper_fops = {
  89         .owner          = THIS_MODULE,
  90         .read           = mmapper_read,
  91         .write          = mmapper_write,
  92         .ioctl          = mmapper_ioctl,
  93         .mmap           = mmapper_mmap,
  94         .open           = mmapper_open,
  95         .release        = mmapper_release,
  96 };
  97
  98 /*
  99  * No locking needed - only used (and modified) by below initcall and exitcall.
 100  */
 101 static struct miscdevice mmapper_dev = {
 102         .minor          = MISC_DYNAMIC_MINOR,
 103         .name           = "mmapper",
 104         .fops           = &mmapper_fops
 105 };
 106
 107 static int __init mmapper_init(void)
 108 {
 109         int err;
 110
 111         printk(KERN_INFO "Mapper v0.1\n");
 112
 113         v_buf = (char *) find_iomem("mmapper", &mmapper_size);
 114         if (mmapper_size == 0) {
 115                 printk(KERN_ERR "mmapper_init - find_iomem failed\n");
 116                 goto out;
 117         }
 118
 119         err = misc_register(&mmapper_dev);
 120         if (err) {
 121                 printk(KERN_ERR "mmapper - misc_register failed, err = %d\n",
 122                        err);
 123                 goto out;
 124         }
 125
 126         p_buf = __pa(v_buf);
 127 out:
 128         return 0;
 129 }
 130
 131 static void mmapper_exit(void)
 132 {
 133         misc_deregister(&mmapper_dev);
 134 }
 135
 136 module_init(mmapper_init);
 137 module_exit(mmapper_exit);
 138
 139 MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
 140 MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");