Merge branch 'mini2440-dev-unlikely' into mini2440-dev
[linux-2.6/mini2440.git] / drivers / char / raw.c
blob64acd05f71c8743330e47a1d9883fc59acc22081
1 /*
2 * linux/drivers/char/raw.c
4 * Front-end raw character devices. These can be bound to any block
5 * devices to provide genuine Unix raw character device semantics.
7 * We reserve minor number 0 for a control interface. ioctl()s on this
8 * device are used to bind the other minor numbers to block devices.
9 */
11 #include <linux/init.h>
12 #include <linux/fs.h>
13 #include <linux/major.h>
14 #include <linux/blkdev.h>
15 #include <linux/module.h>
16 #include <linux/raw.h>
17 #include <linux/capability.h>
18 #include <linux/uio.h>
19 #include <linux/cdev.h>
20 #include <linux/device.h>
21 #include <linux/mutex.h>
22 #include <linux/smp_lock.h>
24 #include <asm/uaccess.h>
26 struct raw_device_data {
27 struct block_device *binding;
28 int inuse;
31 static struct class *raw_class;
32 static struct raw_device_data raw_devices[MAX_RAW_MINORS];
33 static DEFINE_MUTEX(raw_mutex);
34 static const struct file_operations raw_ctl_fops; /* forward declaration */
37 * Open/close code for raw IO.
39 * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
40 * point at the blockdev's address_space and set the file handle to use
41 * O_DIRECT.
43 * Set the device's soft blocksize to the minimum possible. This gives the
44 * finest possible alignment and has no adverse impact on performance.
46 static int raw_open(struct inode *inode, struct file *filp)
48 const int minor = iminor(inode);
49 struct block_device *bdev;
50 int err;
52 if (minor == 0) { /* It is the control device */
53 filp->f_op = &raw_ctl_fops;
54 return 0;
57 lock_kernel();
58 mutex_lock(&raw_mutex);
61 * All we need to do on open is check that the device is bound.
63 bdev = raw_devices[minor].binding;
64 err = -ENODEV;
65 if (!bdev)
66 goto out;
67 igrab(bdev->bd_inode);
68 err = blkdev_get(bdev, filp->f_mode);
69 if (err)
70 goto out;
71 err = bd_claim(bdev, raw_open);
72 if (err)
73 goto out1;
74 err = set_blocksize(bdev, bdev_logical_block_size(bdev));
75 if (err)
76 goto out2;
77 filp->f_flags |= O_DIRECT;
78 filp->f_mapping = bdev->bd_inode->i_mapping;
79 if (++raw_devices[minor].inuse == 1)
80 filp->f_path.dentry->d_inode->i_mapping =
81 bdev->bd_inode->i_mapping;
82 filp->private_data = bdev;
83 mutex_unlock(&raw_mutex);
84 unlock_kernel();
85 return 0;
87 out2:
88 bd_release(bdev);
89 out1:
90 blkdev_put(bdev, filp->f_mode);
91 out:
92 mutex_unlock(&raw_mutex);
93 unlock_kernel();
94 return err;
98 * When the final fd which refers to this character-special node is closed, we
99 * make its ->mapping point back at its own i_data.
101 static int raw_release(struct inode *inode, struct file *filp)
103 const int minor= iminor(inode);
104 struct block_device *bdev;
106 mutex_lock(&raw_mutex);
107 bdev = raw_devices[minor].binding;
108 if (--raw_devices[minor].inuse == 0) {
109 /* Here inode->i_mapping == bdev->bd_inode->i_mapping */
110 inode->i_mapping = &inode->i_data;
111 inode->i_mapping->backing_dev_info = &default_backing_dev_info;
113 mutex_unlock(&raw_mutex);
115 bd_release(bdev);
116 blkdev_put(bdev, filp->f_mode);
117 return 0;
121 * Forward ioctls to the underlying block device.
123 static int
124 raw_ioctl(struct inode *inode, struct file *filp,
125 unsigned int command, unsigned long arg)
127 struct block_device *bdev = filp->private_data;
129 return blkdev_ioctl(bdev, 0, command, arg);
132 static void bind_device(struct raw_config_request *rq)
134 device_destroy(raw_class, MKDEV(RAW_MAJOR, rq->raw_minor));
135 device_create(raw_class, NULL, MKDEV(RAW_MAJOR, rq->raw_minor), NULL,
136 "raw%d", rq->raw_minor);
140 * Deal with ioctls against the raw-device control interface, to bind
141 * and unbind other raw devices.
143 static int raw_ctl_ioctl(struct inode *inode, struct file *filp,
144 unsigned int command, unsigned long arg)
146 struct raw_config_request rq;
147 struct raw_device_data *rawdev;
148 int err = 0;
150 switch (command) {
151 case RAW_SETBIND:
152 case RAW_GETBIND:
154 /* First, find out which raw minor we want */
156 if (copy_from_user(&rq, (void __user *) arg, sizeof(rq))) {
157 err = -EFAULT;
158 goto out;
161 if (rq.raw_minor <= 0 || rq.raw_minor >= MAX_RAW_MINORS) {
162 err = -EINVAL;
163 goto out;
165 rawdev = &raw_devices[rq.raw_minor];
167 if (command == RAW_SETBIND) {
168 dev_t dev;
171 * This is like making block devices, so demand the
172 * same capability
174 if (!capable(CAP_SYS_ADMIN)) {
175 err = -EPERM;
176 goto out;
180 * For now, we don't need to check that the underlying
181 * block device is present or not: we can do that when
182 * the raw device is opened. Just check that the
183 * major/minor numbers make sense.
186 dev = MKDEV(rq.block_major, rq.block_minor);
187 if ((rq.block_major == 0 && rq.block_minor != 0) ||
188 MAJOR(dev) != rq.block_major ||
189 MINOR(dev) != rq.block_minor) {
190 err = -EINVAL;
191 goto out;
194 mutex_lock(&raw_mutex);
195 if (rawdev->inuse) {
196 mutex_unlock(&raw_mutex);
197 err = -EBUSY;
198 goto out;
200 if (rawdev->binding) {
201 bdput(rawdev->binding);
202 module_put(THIS_MODULE);
204 if (rq.block_major == 0 && rq.block_minor == 0) {
205 /* unbind */
206 rawdev->binding = NULL;
207 device_destroy(raw_class,
208 MKDEV(RAW_MAJOR, rq.raw_minor));
209 } else {
210 rawdev->binding = bdget(dev);
211 if (rawdev->binding == NULL)
212 err = -ENOMEM;
213 else {
214 __module_get(THIS_MODULE);
215 bind_device(&rq);
218 mutex_unlock(&raw_mutex);
219 } else {
220 struct block_device *bdev;
222 mutex_lock(&raw_mutex);
223 bdev = rawdev->binding;
224 if (bdev) {
225 rq.block_major = MAJOR(bdev->bd_dev);
226 rq.block_minor = MINOR(bdev->bd_dev);
227 } else {
228 rq.block_major = rq.block_minor = 0;
230 mutex_unlock(&raw_mutex);
231 if (copy_to_user((void __user *)arg, &rq, sizeof(rq))) {
232 err = -EFAULT;
233 goto out;
236 break;
237 default:
238 err = -EINVAL;
239 break;
241 out:
242 return err;
245 static const struct file_operations raw_fops = {
246 .read = do_sync_read,
247 .aio_read = generic_file_aio_read,
248 .write = do_sync_write,
249 .aio_write = blkdev_aio_write,
250 .open = raw_open,
251 .release= raw_release,
252 .ioctl = raw_ioctl,
253 .owner = THIS_MODULE,
256 static const struct file_operations raw_ctl_fops = {
257 .ioctl = raw_ctl_ioctl,
258 .open = raw_open,
259 .owner = THIS_MODULE,
262 static struct cdev raw_cdev;
264 static char *raw_devnode(struct device *dev, mode_t *mode)
266 return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
269 static int __init raw_init(void)
271 dev_t dev = MKDEV(RAW_MAJOR, 0);
272 int ret;
274 ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
275 if (ret)
276 goto error;
278 cdev_init(&raw_cdev, &raw_fops);
279 ret = cdev_add(&raw_cdev, dev, MAX_RAW_MINORS);
280 if (ret) {
281 kobject_put(&raw_cdev.kobj);
282 goto error_region;
285 raw_class = class_create(THIS_MODULE, "raw");
286 if (IS_ERR(raw_class)) {
287 printk(KERN_ERR "Error creating raw class.\n");
288 cdev_del(&raw_cdev);
289 ret = PTR_ERR(raw_class);
290 goto error_region;
292 raw_class->devnode = raw_devnode;
293 device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
295 return 0;
297 error_region:
298 unregister_chrdev_region(dev, MAX_RAW_MINORS);
299 error:
300 return ret;
303 static void __exit raw_exit(void)
305 device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
306 class_destroy(raw_class);
307 cdev_del(&raw_cdev);
308 unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), MAX_RAW_MINORS);
311 module_init(raw_init);
312 module_exit(raw_exit);
313 MODULE_LICENSE("GPL");