e7abc6e3bba016faccb41606c75df5bc0461ecae
[linux-2.6.git] / drivers / acpi / debugfs.c
1 /*
2  * debugfs.c - ACPI debugfs interface to userspace.
3  */
4
5 #include <linux/init.h>
6 #include <linux/module.h>
7 #include <linux/kernel.h>
8 #include <linux/uaccess.h>
9 #include <linux/debugfs.h>
10 #include <acpi/acpi_drivers.h>
11
12 #define _COMPONENT              ACPI_SYSTEM_COMPONENT
13 ACPI_MODULE_NAME("debugfs");
14
15 struct dentry *acpi_debugfs_dir;
16 static struct dentry *cm_dentry;
17
18 /* /sys/kernel/debug/acpi/custom_method */
19
20 static ssize_t cm_write(struct file *file, const char __user * user_buf,
21                         size_t count, loff_t *ppos)
22 {
23         static char *buf;
24         static u32 max_size;
25         static u32 uncopied_bytes;
26
27         struct acpi_table_header table;
28         acpi_status status;
29
30         if (!(*ppos)) {
31                 /* parse the table header to get the table length */
32                 if (count <= sizeof(struct acpi_table_header))
33                         return -EINVAL;
34                 if (copy_from_user(&table, user_buf,
35                                    sizeof(struct acpi_table_header)))
36                         return -EFAULT;
37                 uncopied_bytes = max_size = table.length;
38                 buf = kzalloc(max_size, GFP_KERNEL);
39                 if (!buf)
40                         return -ENOMEM;
41         }
42
43         if (buf == NULL)
44                 return -EINVAL;
45
46         if ((*ppos > max_size) ||
47             (*ppos + count > max_size) ||
48             (*ppos + count < count) ||
49             (count > uncopied_bytes))
50                 return -EINVAL;
51
52         if (copy_from_user(buf + (*ppos), user_buf, count)) {
53                 kfree(buf);
54                 buf = NULL;
55                 return -EFAULT;
56         }
57
58         uncopied_bytes -= count;
59         *ppos += count;
60
61         if (!uncopied_bytes) {
62                 status = acpi_install_method(buf);
63                 kfree(buf);
64                 buf = NULL;
65                 if (ACPI_FAILURE(status))
66                         return -EINVAL;
67                 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
68         }
69
70         return count;
71 }
72
73 static const struct file_operations cm_fops = {
74         .write = cm_write,
75         .llseek = default_llseek,
76 };
77
78 static int __init acpi_custom_method_init(void)
79 {
80         if (!acpi_debugfs_dir)
81                 return -ENOENT;
82
83         cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
84                                         acpi_debugfs_dir, NULL, &cm_fops);
85         if (!cm_dentry)
86                 return -ENODEV;
87
88         return 0;
89 }
90
91 void __init acpi_debugfs_init(void)
92 {
93         acpi_debugfs_dir = debugfs_create_dir("acpi", NULL);
94
95         acpi_custom_method_init();
96 }