path: root/drivers/s390/char/vmur.c

/*
 * Linux driver for System z and s390 unit record devices
 * (z/VM virtual punch, reader, printer)
 *
 * Copyright IBM Corp. 2001, 2007
 * Authors: Malcolm Beattie <beattiem@uk.ibm.com>
 *	    Michael Holzheu <holzheu@de.ibm.com>
 *	    Frank Munzert <munzert@de.ibm.com>
 */

#define KMSG_COMPONENT "vmur"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/cdev.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>
#include <asm/cio.h>
#include <asm/ccwdev.h>
#include <asm/debug.h>
#include <asm/diag.h>

#include "vmur.h"

/*
 * Driver overview
 *
 * Unit record device support is implemented as a character device driver.
 * We can fit at least 16 bits into a device minor number and use the
 * simple method of mapping a character device number with minor abcd
 * to the unit record device with devno abcd.
 * I/O to virtual unit record devices is handled as follows:
 * Reads: Diagnose code 0x14 (input spool file manipulation)
 * is used to read spool data page-wise.
 * Writes: The CCW used is WRITE_CCW_CMD (0x01). The device's record length
 * is available by reading sysfs attr reclen. Each write() to the device
 * must specify an integral multiple (maximal 511) of reclen.
 */

static char ur_banner[] = "z/VM virtual unit record device driver";

MODULE_AUTHOR("IBM Corporation");
MODULE_DESCRIPTION("s390 z/VM virtual unit record device driver");
MODULE_LICENSE("GPL");

static dev_t ur_first_dev_maj_min;
static struct class *vmur_class;
static struct debug_info *vmur_dbf;

/* We put the device's record length (for writes) in the driver_info field */
static struct ccw_device_id ur_ids[] = {
	{ CCWDEV_CU_DI(READER_PUNCH_DEVTYPE, 80) },
	{ CCWDEV_CU_DI(PRINTER_DEVTYPE, 132) },
	{ /* end of list */ }
};

MODULE_DEVICE_TABLE(ccw, ur_ids);

static int ur_probe(struct ccw_device *cdev);
static void ur_remove(struct ccw_device *cdev);
static int ur_set_online(struct ccw_device *cdev);
static int ur_set_offline(struct ccw_device *cdev);

static struct ccw_driver ur_driver = {
	.name		= "vmur",
	.owner		= THIS_MODULE,
	.ids		= ur_ids,
	.probe		= ur_probe,
	.remove		= ur_remove,
	.set_online	= ur_set_online,
	.set_offline	= ur_set_offline,
};

static DEFINE_MUTEX(vmur_mutex);

/*
 * Allocation, freeing, getting and putting of urdev structures
 *
 * Each ur device (urd) contains a reference to its corresponding ccw device
 * (cdev) using the urd->cdev pointer. Each ccw device has a reference to the
 * ur device using the cdev->dev.driver_data pointer.
 *
 * urd references:
 * - ur_probe gets a urd reference, ur_remove drops the reference
 *   (cdev->dev.driver_data)
 * - ur_open gets a urd reference, ur_relase drops the reference
 *   (urf->urd)
 *
 * cdev references:
 * - urdev_alloc get a cdev reference (urd->cdev)
 * - urdev_free drops the cdev reference (urd->cdev)
 *
 * Setting and clearing of cdev->dev.driver_data is protected by the ccwdev lock
 */
static struct urdev *urdev_alloc(struct ccw_device *cdev)
{
	struct urdev *urd;

	urd = kzalloc(sizeof(struct urdev), GFP_KERNEL);
	if (!urd)
		return NULL;
	urd->reclen = cdev->id.driver_info;
	ccw_device_get_id(cdev, &urd->dev_id);
	mutex_init(&urd->io_mutex);
	init_waitqueue_head(&urd->wait);
	spin_lock_init(&urd->open_lock);
	atomic_set(&urd->ref_count,  1);
	urd->cdev = cdev;
	get_device(&cdev->dev);
	return urd;
}

static void urdev_free(struct urdev *urd)
{
	TRACE("urdev_free: %p\n", urd);
	if (urd->cdev)
		put_device(&urd->cdev->dev);
	kfree(urd);
}

static void urdev_get(struct urdev *urd)
{
	atomic_inc(&urd->ref_count);
}

static struct urdev *urdev_get_from_cdev(struct ccw_device *cdev)
{
	struct urdev *urd;
	unsigned long flags;

	spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
	urd = cdev->dev.driver_data;
	if (urd)
		urdev_get(urd);
	spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
	return urd;
}

static struct urdev *urdev_get_from_devno(u16 devno)
{
	char bus_id[16];
	struct ccw_device *cdev;
	struct urdev *urd;

	sprintf(bus_id, "0.0.%04x", devno);
	cdev = get_ccwdev_by_busid(&ur_driver, bus_id);
	if (!cdev)
		return NULL;
	urd = urdev_get_from_cdev(cdev);
	put_device(&cdev->dev);
	return urd;
}

static void urdev_put(struct urdev *urd)
{
	if (atomic_dec_and_test(&urd->ref_count))
		urdev_free(urd);
}

/*
 * Low-level functions to do I/O to a ur device.
 *     alloc_chan_prog
 *     free_chan_prog
 *     do_ur_io
 *     ur_int_handler
 *
 * alloc_chan_prog allocates and builds the channel program
 * free_chan_prog frees memory of the channel program
 *
 * do_ur_io issues the channel program to the device and blocks waiting
 * on a completion event it publishes at