xref: /openbmc/linux/arch/um/drivers/mmapper_kern.c (revision bd6859fe) 
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");
143