[PATCH] mark struct file_operations const 5
[linux-2.6.git] / drivers / s390 / char / vmcp.c
1 /*
2  * Copyright (C) 2004,2005 IBM Corporation
3  * Interface implementation for communication with the z/VM control program
4  * Author(s): Christian Borntraeger <cborntra@de.ibm.com>
5  *
6  *
7  * z/VMs CP offers the possibility to issue commands via the diagnose code 8
8  * this driver implements a character device that issues these commands and
9  * returns the answer of CP.
10
11  * The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS
12  */
13
14 #include <linux/fs.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/miscdevice.h>
18 #include <linux/module.h>
19 #include <asm/cpcmd.h>
20 #include <asm/debug.h>
21 #include <asm/uaccess.h>
22 #include "vmcp.h"
23
24 MODULE_LICENSE("GPL");
25 MODULE_AUTHOR("Christian Borntraeger <cborntra@de.ibm.com>");
26 MODULE_DESCRIPTION("z/VM CP interface");
27
28 static debug_info_t *vmcp_debug;
29
30 static int vmcp_open(struct inode *inode, struct file *file)
31 {
32         struct vmcp_session *session;
33
34         if (!capable(CAP_SYS_ADMIN))
35                 return -EPERM;
36
37         session = kmalloc(sizeof(*session), GFP_KERNEL);
38         if (!session)
39                 return -ENOMEM;
40         session->bufsize = PAGE_SIZE;
41         session->response = NULL;
42         session->resp_size = 0;
43         init_MUTEX(&session->mutex);
44         file->private_data = session;
45         return nonseekable_open(inode, file);
46 }
47
48 static int vmcp_release(struct inode *inode, struct file *file)
49 {
50         struct vmcp_session *session;
51
52         session = (struct vmcp_session *)file->private_data;
53         file->private_data = NULL;
54         free_pages((unsigned long)session->response, get_order(session->bufsize));
55         kfree(session);
56         return 0;
57 }
58
59 static ssize_t
60 vmcp_read(struct file *file, char __user * buff, size_t count, loff_t * ppos)
61 {
62         size_t tocopy;
63         struct vmcp_session *session;
64
65         session = (struct vmcp_session *)file->private_data;
66         if (down_interruptible(&session->mutex))
67                 return -ERESTARTSYS;
68         if (!session->response) {
69                 up(&session->mutex);
70                 return 0;
71         }
72         if (*ppos > session->resp_size) {
73                 up(&session->mutex);
74                 return 0;
75         }
76         tocopy = min(session->resp_size - (size_t) (*ppos), count);
77         tocopy = min(tocopy,session->bufsize - (size_t) (*ppos));
78
79         if (copy_to_user(buff, session->response + (*ppos), tocopy)) {
80                 up(&session->mutex);
81                 return -EFAULT;
82         }
83         up(&session->mutex);
84         *ppos += tocopy;
85         return tocopy;
86 }
87
88 static ssize_t
89 vmcp_write(struct file *file, const char __user * buff, size_t count,
90            loff_t * ppos)
91 {
92         char *cmd;
93         struct vmcp_session *session;
94
95         if (count > 240)
96                 return -EINVAL;
97         cmd = kmalloc(count + 1, GFP_KERNEL);
98         if (!cmd)
99                 return -ENOMEM;
100         if (copy_from_user(cmd, buff, count)) {
101                 kfree(cmd);
102                 return -EFAULT;
103         }
104         cmd[count] = '\0';
105         session = (struct vmcp_session *)file->private_data;
106         if (down_interruptible(&session->mutex)) {
107                 kfree(cmd);
108                 return -ERESTARTSYS;
109         }
110         if (!session->response)
111                 session->response = (char *)__get_free_pages(GFP_KERNEL
112                                                 | __GFP_REPEAT  | GFP_DMA,
113                                                 get_order(session->bufsize));
114         if (!session->response) {
115                 up(&session->mutex);
116                 kfree(cmd);
117                 return -ENOMEM;
118         }
119         debug_text_event(vmcp_debug, 1, cmd);
120         session->resp_size = cpcmd(cmd, session->response,
121                                      session->bufsize,
122                                      &session->resp_code);
123         up(&session->mutex);
124         kfree(cmd);
125         *ppos = 0;              /* reset the file pointer after a command */
126         return count;
127 }
128
129
130 /*
131  * These ioctls are available, as the semantics of the diagnose 8 call
132  * does not fit very well into a Linux call. Diagnose X'08' is described in
133  * CP Programming Services SC24-6084-00
134  *
135  * VMCP_GETCODE: gives the CP return code back to user space
136  * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
137  * expects adjacent pages in real storage and to make matters worse, we
138  * dont know the size of the response. Therefore we default to PAGESIZE and
139  * let userspace to change the response size, if userspace expects a bigger
140  * response
141  */
142 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
143 {
144         struct vmcp_session *session;
145         int temp;
146
147         session = (struct vmcp_session *)file->private_data;
148         if (down_interruptible(&session->mutex))
149                 return -ERESTARTSYS;
150         switch (cmd) {
151         case VMCP_GETCODE:
152                 temp = session->resp_code;
153                 up(&session->mutex);
154                 return put_user(temp, (int __user *)arg);
155         case VMCP_SETBUF:
156                 free_pages((unsigned long)session->response,
157                                 get_order(session->bufsize));
158                 session->response=NULL;
159                 temp = get_user(session->bufsize, (int __user *)arg);
160                 if (get_order(session->bufsize) > 8) {
161                         session->bufsize = PAGE_SIZE;
162                         temp = -EINVAL;
163                 }
164                 up(&session->mutex);
165                 return temp;
166         case VMCP_GETSIZE:
167                 temp = session->resp_size;
168                 up(&session->mutex);
169                 return put_user(temp, (int __user *)arg);
170         default:
171                 up(&session->mutex);
172                 return -ENOIOCTLCMD;
173         }
174 }
175
176 static const struct file_operations vmcp_fops = {
177         .owner          = THIS_MODULE,
178         .open           = &vmcp_open,
179         .release        = &vmcp_release,
180         .read           = &vmcp_read,
181         .llseek         = &no_llseek,
182         .write          = &vmcp_write,
183         .unlocked_ioctl = &vmcp_ioctl,
184         .compat_ioctl   = &vmcp_ioctl
185 };
186
187 static struct miscdevice vmcp_dev = {
188         .name   = "vmcp",
189         .minor  = MISC_DYNAMIC_MINOR,
190         .fops   = &vmcp_fops,
191 };
192
193 static int __init vmcp_init(void)
194 {
195         int ret;
196
197         if (!MACHINE_IS_VM) {
198                 printk(KERN_WARNING
199                        "z/VM CP interface is only available under z/VM\n");
200                 return -ENODEV;
201         }
202         ret = misc_register(&vmcp_dev);
203         if (!ret)
204                 printk(KERN_INFO "z/VM CP interface loaded\n");
205         else
206                 printk(KERN_WARNING
207                        "z/VM CP interface not loaded. Could not register misc device.\n");
208         vmcp_debug = debug_register("vmcp", 1, 1, 240);
209         debug_register_view(vmcp_debug, &debug_hex_ascii_view);
210         return ret;
211 }
212
213 static void __exit vmcp_exit(void)
214 {
215         WARN_ON(misc_deregister(&vmcp_dev) != 0);
216         debug_unregister(vmcp_debug);
217         printk(KERN_INFO "z/VM CP interface unloaded.\n");
218 }
219
220 module_init(vmcp_init);
221 module_exit(vmcp_exit);