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