mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
368 lines
8.9 KiB
C
368 lines
8.9 KiB
C
/*
|
|
* HMC Drive CD/DVD Device
|
|
*
|
|
* Copyright IBM Corp. 2013
|
|
* Author(s): Ralf Hoppe (rhoppe@de.ibm.com)
|
|
*
|
|
* This file provides a Linux "misc" character device for access to an
|
|
* assigned HMC drive CD/DVD-ROM. It works as follows: First create the
|
|
* device by calling hmcdrv_dev_init(). After open() a lseek(fd, 0,
|
|
* SEEK_END) indicates that a new FTP command follows (not needed on the
|
|
* first command after open). Then write() the FTP command ASCII string
|
|
* to it, e.g. "dir /" or "nls <directory>" or "get <filename>". At the
|
|
* end read() the response.
|
|
*/
|
|
|
|
#define KMSG_COMPONENT "hmcdrv"
|
|
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/cdev.h>
|
|
#include <linux/miscdevice.h>
|
|
#include <linux/device.h>
|
|
#include <linux/capability.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/uaccess.h>
|
|
|
|
#include "hmcdrv_dev.h"
|
|
#include "hmcdrv_ftp.h"
|
|
|
|
/* If the following macro is defined, then the HMC device creates it's own
|
|
* separated device class (and dynamically assigns a major number). If not
|
|
* defined then the HMC device is assigned to the "misc" class devices.
|
|
*
|
|
#define HMCDRV_DEV_CLASS "hmcftp"
|
|
*/
|
|
|
|
#define HMCDRV_DEV_NAME "hmcdrv"
|
|
#define HMCDRV_DEV_BUSY_DELAY 500 /* delay between -EBUSY trials in ms */
|
|
#define HMCDRV_DEV_BUSY_RETRIES 3 /* number of retries on -EBUSY */
|
|
|
|
struct hmcdrv_dev_node {
|
|
|
|
#ifdef HMCDRV_DEV_CLASS
|
|
struct cdev dev; /* character device structure */
|
|
umode_t mode; /* mode of device node (unused, zero) */
|
|
#else
|
|
struct miscdevice dev; /* "misc" device structure */
|
|
#endif
|
|
|
|
};
|
|
|
|
static int hmcdrv_dev_open(struct inode *inode, struct file *fp);
|
|
static int hmcdrv_dev_release(struct inode *inode, struct file *fp);
|
|
static loff_t hmcdrv_dev_seek(struct file *fp, loff_t pos, int whence);
|
|
static ssize_t hmcdrv_dev_read(struct file *fp, char __user *ubuf,
|
|
size_t len, loff_t *pos);
|
|
static ssize_t hmcdrv_dev_write(struct file *fp, const char __user *ubuf,
|
|
size_t len, loff_t *pos);
|
|
static ssize_t hmcdrv_dev_transfer(char __kernel *cmd, loff_t offset,
|
|
char __user *buf, size_t len);
|
|
|
|
/*
|
|
* device operations
|
|
*/
|
|
static const struct file_operations hmcdrv_dev_fops = {
|
|
.open = hmcdrv_dev_open,
|
|
.llseek = hmcdrv_dev_seek,
|
|
.release = hmcdrv_dev_release,
|
|
.read = hmcdrv_dev_read,
|
|
.write = hmcdrv_dev_write,
|
|
};
|
|
|
|
static struct hmcdrv_dev_node hmcdrv_dev; /* HMC device struct (static) */
|
|
|
|
#ifdef HMCDRV_DEV_CLASS
|
|
|
|
static struct class *hmcdrv_dev_class; /* device class pointer */
|
|
static dev_t hmcdrv_dev_no; /* device number (major/minor) */
|
|
|
|
/**
|
|
* hmcdrv_dev_name() - provides a naming hint for a device node in /dev
|
|
* @dev: device for which the naming/mode hint is
|
|
* @mode: file mode for device node created in /dev
|
|
*
|
|
* See: devtmpfs.c, function devtmpfs_create_node()
|
|
*
|
|
* Return: recommended device file name in /dev
|
|
*/
|
|
static char *hmcdrv_dev_name(struct device *dev, umode_t *mode)
|
|
{
|
|
char *nodename = NULL;
|
|
const char *devname = dev_name(dev); /* kernel device name */
|
|
|
|
if (devname)
|
|
nodename = kasprintf(GFP_KERNEL, "%s", devname);
|
|
|
|
/* on device destroy (rmmod) the mode pointer may be NULL
|
|
*/
|
|
if (mode)
|
|
*mode = hmcdrv_dev.mode;
|
|
|
|
return nodename;
|
|
}
|
|
|
|
#endif /* HMCDRV_DEV_CLASS */
|
|
|
|
/*
|
|
* open()
|
|
*/
|
|
static int hmcdrv_dev_open(struct inode *inode, struct file *fp)
|
|
{
|
|
int rc;
|
|
|
|
/* check for non-blocking access, which is really unsupported
|
|
*/
|
|
if (fp->f_flags & O_NONBLOCK)
|
|
return -EINVAL;
|
|
|
|
/* Because it makes no sense to open this device read-only (then a
|
|
* FTP command cannot be emitted), we respond with an error.
|
|
*/
|
|
if ((fp->f_flags & O_ACCMODE) == O_RDONLY)
|
|
return -EINVAL;
|
|
|
|
/* prevent unloading this module as long as anyone holds the
|
|
* device file open - so increment the reference count here
|
|
*/
|
|
if (!try_module_get(THIS_MODULE))
|
|
return -ENODEV;
|
|
|
|
fp->private_data = NULL; /* no command yet */
|
|
rc = hmcdrv_ftp_startup();
|
|
if (rc)
|
|
module_put(THIS_MODULE);
|
|
|
|
pr_debug("open file '/dev/%pD' with return code %d\n", fp, rc);
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* release()
|
|
*/
|
|
static int hmcdrv_dev_release(struct inode *inode, struct file *fp)
|
|
{
|
|
pr_debug("closing file '/dev/%pD'\n", fp);
|
|
kfree(fp->private_data);
|
|
fp->private_data = NULL;
|
|
hmcdrv_ftp_shutdown();
|
|
module_put(THIS_MODULE);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* lseek()
|
|
*/
|
|
static loff_t hmcdrv_dev_seek(struct file *fp, loff_t pos, int whence)
|
|
{
|
|
switch (whence) {
|
|
case SEEK_CUR: /* relative to current file position */
|
|
pos += fp->f_pos; /* new position stored in 'pos' */
|
|
break;
|
|
|
|
case SEEK_SET: /* absolute (relative to beginning of file) */
|
|
break; /* SEEK_SET */
|
|
|
|
/* We use SEEK_END as a special indicator for a SEEK_SET
|
|
* (set absolute position), combined with a FTP command
|
|
* clear.
|
|
*/
|
|
case SEEK_END:
|
|
if (fp->private_data) {
|
|
kfree(fp->private_data);
|
|
fp->private_data = NULL;
|
|
}
|
|
|
|
break; /* SEEK_END */
|
|
|
|
default: /* SEEK_DATA, SEEK_HOLE: unsupported */
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (pos < 0)
|
|
return -EINVAL;
|
|
|
|
if (fp->f_pos != pos)
|
|
++fp->f_version;
|
|
|
|
fp->f_pos = pos;
|
|
return pos;
|
|
}
|
|
|
|
/*
|
|
* transfer (helper function)
|
|
*/
|
|
static ssize_t hmcdrv_dev_transfer(char __kernel *cmd, loff_t offset,
|
|
char __user *buf, size_t len)
|
|
{
|
|
ssize_t retlen;
|
|
unsigned trials = HMCDRV_DEV_BUSY_RETRIES;
|
|
|
|
do {
|
|
retlen = hmcdrv_ftp_cmd(cmd, offset, buf, len);
|
|
|
|
if (retlen != -EBUSY)
|
|
break;
|
|
|
|
msleep(HMCDRV_DEV_BUSY_DELAY);
|
|
|
|
} while (--trials > 0);
|
|
|
|
return retlen;
|
|
}
|
|
|
|
/*
|
|
* read()
|
|
*/
|
|
static ssize_t hmcdrv_dev_read(struct file *fp, char __user *ubuf,
|
|
size_t len, loff_t *pos)
|
|
{
|
|
ssize_t retlen;
|
|
|
|
if (((fp->f_flags & O_ACCMODE) == O_WRONLY) ||
|
|
(fp->private_data == NULL)) { /* no FTP cmd defined ? */
|
|
return -EBADF;
|
|
}
|
|
|
|
retlen = hmcdrv_dev_transfer((char *) fp->private_data,
|
|
*pos, ubuf, len);
|
|
|
|
pr_debug("read from file '/dev/%pD' at %lld returns %zd/%zu\n",
|
|
fp, (long long) *pos, retlen, len);
|
|
|
|
if (retlen > 0)
|
|
*pos += retlen;
|
|
|
|
return retlen;
|
|
}
|
|
|
|
/*
|
|
* write()
|
|
*/
|
|
static ssize_t hmcdrv_dev_write(struct file *fp, const char __user *ubuf,
|
|
size_t len, loff_t *pos)
|
|
{
|
|
ssize_t retlen;
|
|
|
|
pr_debug("writing file '/dev/%pD' at pos. %lld with length %zd\n",
|
|
fp, (long long) *pos, len);
|
|
|
|
if (!fp->private_data) { /* first expect a cmd write */
|
|
fp->private_data = kmalloc(len + 1, GFP_KERNEL);
|
|
|
|
if (!fp->private_data)
|
|
return -ENOMEM;
|
|
|
|
if (!copy_from_user(fp->private_data, ubuf, len)) {
|
|
((char *)fp->private_data)[len] = '\0';
|
|
return len;
|
|
}
|
|
|
|
kfree(fp->private_data);
|
|
fp->private_data = NULL;
|
|
return -EFAULT;
|
|
}
|
|
|
|
retlen = hmcdrv_dev_transfer((char *) fp->private_data,
|
|
*pos, (char __user *) ubuf, len);
|
|
if (retlen > 0)
|
|
*pos += retlen;
|
|
|
|
pr_debug("write to file '/dev/%pD' returned %zd\n", fp, retlen);
|
|
|
|
return retlen;
|
|
}
|
|
|
|
/**
|
|
* hmcdrv_dev_init() - creates a HMC drive CD/DVD device
|
|
*
|
|
* This function creates a HMC drive CD/DVD kernel device and an associated
|
|
* device under /dev, using a dynamically allocated major number.
|
|
*
|
|
* Return: 0 on success, else an error code.
|
|
*/
|
|
int hmcdrv_dev_init(void)
|
|
{
|
|
int rc;
|
|
|
|
#ifdef HMCDRV_DEV_CLASS
|
|
struct device *dev;
|
|
|
|
rc = alloc_chrdev_region(&hmcdrv_dev_no, 0, 1, HMCDRV_DEV_NAME);
|
|
|
|
if (rc)
|
|
goto out_err;
|
|
|
|
cdev_init(&hmcdrv_dev.dev, &hmcdrv_dev_fops);
|
|
hmcdrv_dev.dev.owner = THIS_MODULE;
|
|
rc = cdev_add(&hmcdrv_dev.dev, hmcdrv_dev_no, 1);
|
|
|
|
if (rc)
|
|
goto out_unreg;
|
|
|
|
/* At this point the character device exists in the kernel (see
|
|
* /proc/devices), but not under /dev nor /sys/devices/virtual. So
|
|
* we have to create an associated class (see /sys/class).
|
|
*/
|
|
hmcdrv_dev_class = class_create(THIS_MODULE, HMCDRV_DEV_CLASS);
|
|
|
|
if (IS_ERR(hmcdrv_dev_class)) {
|
|
rc = PTR_ERR(hmcdrv_dev_class);
|
|
goto out_devdel;
|
|
}
|
|
|
|
/* Finally a device node in /dev has to be established (as 'mkdev'
|
|
* does from the command line). Notice that assignment of a device
|
|
* node name/mode function is optional (only for mode != 0600).
|
|
*/
|
|
hmcdrv_dev.mode = 0; /* "unset" */
|
|
hmcdrv_dev_class->devnode = hmcdrv_dev_name;
|
|
|
|
dev = device_create(hmcdrv_dev_class, NULL, hmcdrv_dev_no, NULL,
|
|
"%s", HMCDRV_DEV_NAME);
|
|
if (!IS_ERR(dev))
|
|
return 0;
|
|
|
|
rc = PTR_ERR(dev);
|
|
class_destroy(hmcdrv_dev_class);
|
|
hmcdrv_dev_class = NULL;
|
|
|
|
out_devdel:
|
|
cdev_del(&hmcdrv_dev.dev);
|
|
|
|
out_unreg:
|
|
unregister_chrdev_region(hmcdrv_dev_no, 1);
|
|
|
|
out_err:
|
|
|
|
#else /* !HMCDRV_DEV_CLASS */
|
|
hmcdrv_dev.dev.minor = MISC_DYNAMIC_MINOR;
|
|
hmcdrv_dev.dev.name = HMCDRV_DEV_NAME;
|
|
hmcdrv_dev.dev.fops = &hmcdrv_dev_fops;
|
|
hmcdrv_dev.dev.mode = 0; /* finally produces 0600 */
|
|
rc = misc_register(&hmcdrv_dev.dev);
|
|
#endif /* HMCDRV_DEV_CLASS */
|
|
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* hmcdrv_dev_exit() - destroys a HMC drive CD/DVD device
|
|
*/
|
|
void hmcdrv_dev_exit(void)
|
|
{
|
|
#ifdef HMCDRV_DEV_CLASS
|
|
if (!IS_ERR_OR_NULL(hmcdrv_dev_class)) {
|
|
device_destroy(hmcdrv_dev_class, hmcdrv_dev_no);
|
|
class_destroy(hmcdrv_dev_class);
|
|
}
|
|
|
|
cdev_del(&hmcdrv_dev.dev);
|
|
unregister_chrdev_region(hmcdrv_dev_no, 1);
|
|
#else /* !HMCDRV_DEV_CLASS */
|
|
misc_deregister(&hmcdrv_dev.dev);
|
|
#endif /* HMCDRV_DEV_CLASS */
|
|
}
|