2 * HMC Drive CD/DVD Device
4 * Copyright IBM Corp. 2013
5 * Author(s): Ralf Hoppe (rhoppe@de.ibm.com)
7 * This file provides a Linux "misc" character device for access to an
8 * assigned HMC drive CD/DVD-ROM. It works as follows: First create the
9 * device by calling hmcdrv_dev_init(). After open() a lseek(fd, 0,
10 * SEEK_END) indicates that a new FTP command follows (not needed on the
11 * first command after open). Then write() the FTP command ASCII string
12 * to it, e.g. "dir /" or "nls <directory>" or "get <filename>". At the
13 * end read() the response.
16 #define KMSG_COMPONENT "hmcdrv"
17 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/slab.h>
23 #include <linux/cdev.h>
24 #include <linux/miscdevice.h>
25 #include <linux/device.h>
26 #include <linux/capability.h>
27 #include <linux/delay.h>
28 #include <linux/uaccess.h>
30 #include "hmcdrv_dev.h"
31 #include "hmcdrv_ftp.h"
33 /* If the following macro is defined, then the HMC device creates it's own
34 * separated device class (and dynamically assigns a major number). If not
35 * defined then the HMC device is assigned to the "misc" class devices.
37 #define HMCDRV_DEV_CLASS "hmcftp"
40 #define HMCDRV_DEV_NAME "hmcdrv"
41 #define HMCDRV_DEV_BUSY_DELAY 500 /* delay between -EBUSY trials in ms */
42 #define HMCDRV_DEV_BUSY_RETRIES 3 /* number of retries on -EBUSY */
44 struct hmcdrv_dev_node
{
46 #ifdef HMCDRV_DEV_CLASS
47 struct cdev dev
; /* character device structure */
48 umode_t mode
; /* mode of device node (unused, zero) */
50 struct miscdevice dev
; /* "misc" device structure */
55 static int hmcdrv_dev_open(struct inode
*inode
, struct file
*fp
);
56 static int hmcdrv_dev_release(struct inode
*inode
, struct file
*fp
);
57 static loff_t
hmcdrv_dev_seek(struct file
*fp
, loff_t pos
, int whence
);
58 static ssize_t
hmcdrv_dev_read(struct file
*fp
, char __user
*ubuf
,
59 size_t len
, loff_t
*pos
);
60 static ssize_t
hmcdrv_dev_write(struct file
*fp
, const char __user
*ubuf
,
61 size_t len
, loff_t
*pos
);
62 static ssize_t
hmcdrv_dev_transfer(char __kernel
*cmd
, loff_t offset
,
63 char __user
*buf
, size_t len
);
68 static const struct file_operations hmcdrv_dev_fops
= {
69 .open
= hmcdrv_dev_open
,
70 .llseek
= hmcdrv_dev_seek
,
71 .release
= hmcdrv_dev_release
,
72 .read
= hmcdrv_dev_read
,
73 .write
= hmcdrv_dev_write
,
76 static struct hmcdrv_dev_node hmcdrv_dev
; /* HMC device struct (static) */
78 #ifdef HMCDRV_DEV_CLASS
80 static struct class *hmcdrv_dev_class
; /* device class pointer */
81 static dev_t hmcdrv_dev_no
; /* device number (major/minor) */
84 * hmcdrv_dev_name() - provides a naming hint for a device node in /dev
85 * @dev: device for which the naming/mode hint is
86 * @mode: file mode for device node created in /dev
88 * See: devtmpfs.c, function devtmpfs_create_node()
90 * Return: recommended device file name in /dev
92 static char *hmcdrv_dev_name(struct device
*dev
, umode_t
*mode
)
94 char *nodename
= NULL
;
95 const char *devname
= dev_name(dev
); /* kernel device name */
98 nodename
= kasprintf(GFP_KERNEL
, "%s", devname
);
100 /* on device destroy (rmmod) the mode pointer may be NULL
103 *mode
= hmcdrv_dev
.mode
;
108 #endif /* HMCDRV_DEV_CLASS */
113 static int hmcdrv_dev_open(struct inode
*inode
, struct file
*fp
)
117 /* check for non-blocking access, which is really unsupported
119 if (fp
->f_flags
& O_NONBLOCK
)
122 /* Because it makes no sense to open this device read-only (then a
123 * FTP command cannot be emitted), we respond with an error.
125 if ((fp
->f_flags
& O_ACCMODE
) == O_RDONLY
)
128 /* prevent unloading this module as long as anyone holds the
129 * device file open - so increment the reference count here
131 if (!try_module_get(THIS_MODULE
))
134 fp
->private_data
= NULL
; /* no command yet */
135 rc
= hmcdrv_ftp_startup();
137 module_put(THIS_MODULE
);
139 pr_debug("open file '/dev/%s' with return code %d\n",
140 fp
->f_dentry
->d_name
.name
, rc
);
147 static int hmcdrv_dev_release(struct inode
*inode
, struct file
*fp
)
149 pr_debug("closing file '/dev/%s'\n", fp
->f_dentry
->d_name
.name
);
150 kfree(fp
->private_data
);
151 fp
->private_data
= NULL
;
152 hmcdrv_ftp_shutdown();
153 module_put(THIS_MODULE
);
160 static loff_t
hmcdrv_dev_seek(struct file
*fp
, loff_t pos
, int whence
)
163 case SEEK_CUR
: /* relative to current file position */
164 pos
+= fp
->f_pos
; /* new position stored in 'pos' */
167 case SEEK_SET
: /* absolute (relative to beginning of file) */
168 break; /* SEEK_SET */
170 /* We use SEEK_END as a special indicator for a SEEK_SET
171 * (set absolute position), combined with a FTP command
175 if (fp
->private_data
) {
176 kfree(fp
->private_data
);
177 fp
->private_data
= NULL
;
180 break; /* SEEK_END */
182 default: /* SEEK_DATA, SEEK_HOLE: unsupported */
189 if (fp
->f_pos
!= pos
)
197 * transfer (helper function)
199 static ssize_t
hmcdrv_dev_transfer(char __kernel
*cmd
, loff_t offset
,
200 char __user
*buf
, size_t len
)
203 unsigned trials
= HMCDRV_DEV_BUSY_RETRIES
;
206 retlen
= hmcdrv_ftp_cmd(cmd
, offset
, buf
, len
);
208 if (retlen
!= -EBUSY
)
211 msleep(HMCDRV_DEV_BUSY_DELAY
);
213 } while (--trials
> 0);
221 static ssize_t
hmcdrv_dev_read(struct file
*fp
, char __user
*ubuf
,
222 size_t len
, loff_t
*pos
)
226 if (((fp
->f_flags
& O_ACCMODE
) == O_WRONLY
) ||
227 (fp
->private_data
== NULL
)) { /* no FTP cmd defined ? */
231 retlen
= hmcdrv_dev_transfer((char *) fp
->private_data
,
234 pr_debug("read from file '/dev/%s' at %lld returns %zd/%zu\n",
235 fp
->f_dentry
->d_name
.name
, (long long) *pos
, retlen
, len
);
246 static ssize_t
hmcdrv_dev_write(struct file
*fp
, const char __user
*ubuf
,
247 size_t len
, loff_t
*pos
)
251 pr_debug("writing file '/dev/%s' at pos. %lld with length %zd\n",
252 fp
->f_dentry
->d_name
.name
, (long long) *pos
, len
);
254 if (!fp
->private_data
) { /* first expect a cmd write */
255 fp
->private_data
= kmalloc(len
+ 1, GFP_KERNEL
);
257 if (!fp
->private_data
)
260 if (!copy_from_user(fp
->private_data
, ubuf
, len
)) {
261 ((char *)fp
->private_data
)[len
] = '\0';
265 kfree(fp
->private_data
);
266 fp
->private_data
= NULL
;
270 retlen
= hmcdrv_dev_transfer((char *) fp
->private_data
,
271 *pos
, (char __user
*) ubuf
, len
);
275 pr_debug("write to file '/dev/%s' returned %zd\n",
276 fp
->f_dentry
->d_name
.name
, retlen
);
282 * hmcdrv_dev_init() - creates a HMC drive CD/DVD device
284 * This function creates a HMC drive CD/DVD kernel device and an associated
285 * device under /dev, using a dynamically allocated major number.
287 * Return: 0 on success, else an error code.
289 int hmcdrv_dev_init(void)
293 #ifdef HMCDRV_DEV_CLASS
296 rc
= alloc_chrdev_region(&hmcdrv_dev_no
, 0, 1, HMCDRV_DEV_NAME
);
301 cdev_init(&hmcdrv_dev
.dev
, &hmcdrv_dev_fops
);
302 hmcdrv_dev
.dev
.owner
= THIS_MODULE
;
303 rc
= cdev_add(&hmcdrv_dev
.dev
, hmcdrv_dev_no
, 1);
308 /* At this point the character device exists in the kernel (see
309 * /proc/devices), but not under /dev nor /sys/devices/virtual. So
310 * we have to create an associated class (see /sys/class).
312 hmcdrv_dev_class
= class_create(THIS_MODULE
, HMCDRV_DEV_CLASS
);
314 if (IS_ERR(hmcdrv_dev_class
)) {
315 rc
= PTR_ERR(hmcdrv_dev_class
);
319 /* Finally a device node in /dev has to be established (as 'mkdev'
320 * does from the command line). Notice that assignment of a device
321 * node name/mode function is optional (only for mode != 0600).
323 hmcdrv_dev
.mode
= 0; /* "unset" */
324 hmcdrv_dev_class
->devnode
= hmcdrv_dev_name
;
326 dev
= device_create(hmcdrv_dev_class
, NULL
, hmcdrv_dev_no
, NULL
,
327 "%s", HMCDRV_DEV_NAME
);
332 class_destroy(hmcdrv_dev_class
);
333 hmcdrv_dev_class
= NULL
;
336 cdev_del(&hmcdrv_dev
.dev
);
339 unregister_chrdev_region(hmcdrv_dev_no
, 1);
343 #else /* !HMCDRV_DEV_CLASS */
344 hmcdrv_dev
.dev
.minor
= MISC_DYNAMIC_MINOR
;
345 hmcdrv_dev
.dev
.name
= HMCDRV_DEV_NAME
;
346 hmcdrv_dev
.dev
.fops
= &hmcdrv_dev_fops
;
347 hmcdrv_dev
.dev
.mode
= 0; /* finally produces 0600 */
348 rc
= misc_register(&hmcdrv_dev
.dev
);
349 #endif /* HMCDRV_DEV_CLASS */
355 * hmcdrv_dev_exit() - destroys a HMC drive CD/DVD device
357 void hmcdrv_dev_exit(void)
359 #ifdef HMCDRV_DEV_CLASS
360 if (!IS_ERR_OR_NULL(hmcdrv_dev_class
)) {
361 device_destroy(hmcdrv_dev_class
, hmcdrv_dev_no
);
362 class_destroy(hmcdrv_dev_class
);
365 cdev_del(&hmcdrv_dev
.dev
);
366 unregister_chrdev_region(hmcdrv_dev_no
, 1);
367 #else /* !HMCDRV_DEV_CLASS */
368 misc_deregister(&hmcdrv_dev
.dev
);
369 #endif /* HMCDRV_DEV_CLASS */