diff options
Diffstat (limited to 'drivers/s390/char/hmcdrv_dev.c')
| -rw-r--r-- | drivers/s390/char/hmcdrv_dev.c | 368 |
1 files changed, 368 insertions, 0 deletions
diff --git a/drivers/s390/char/hmcdrv_dev.c b/drivers/s390/char/hmcdrv_dev.c new file mode 100644 index 000000000..43cee7fcd --- /dev/null +++ b/drivers/s390/char/hmcdrv_dev.c @@ -0,0 +1,368 @@ +/* + * 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 */ +} |