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s390/hmcdrv: HMC drive CD/DVD access

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This device driver allows accessing a HMC drive CD/DVD-ROM.
It can be used in a LPAR and z/VM environment.

Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ralf Hoppe <rhoppe@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Ralf Hoppe
2013-04-08 09:52:57 +02:00
committed by Martin Schwidefsky
parent ea61a579ab
commit 8f933b1043
17 changed files with 1793 additions and 0 deletions
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370
drivers/s390/char/hmcdrv_dev.c Normal file
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/*
* 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/%s' with return code %d\n",
fp->f_dentry->d_name.name, rc);
return rc;
}
/*
* release()
*/
static int hmcdrv_dev_release(struct inode *inode, struct file *fp)
{
pr_debug("closing file '/dev/%s'\n", fp->f_dentry->d_name.name);
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/%s' at %lld returns %zd/%zu\n",
fp->f_dentry->d_name.name, (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/%s' at pos. %lld with length %zd\n",
fp->f_dentry->d_name.name, (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/%s' returned %zd\n",
fp->f_dentry->d_name.name, 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 */
}