[S390] cio: dont forget to set last slot to NULL in ccw_uevent().

[linux-block.git] / drivers / s390 / cio / cmf.c

/*
 * linux/drivers/s390/cio/cmf.c
 *
 * Linux on zSeries Channel Measurement Facility support
 *
 * Copyright 2000,2006 IBM Corporation
 *
 * Authors: Arnd Bergmann <arndb@de.ibm.com>
 *	    Cornelia Huck <cornelia.huck@de.ibm.com>
 *
 * original idea from Natarajan Krishnaswami <nkrishna@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/bootmem.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/timex.h>	/* get_clock() */

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/cmb.h>
#include <asm/div64.h>

#include "cio.h"
#include "css.h"
#include "device.h"
#include "ioasm.h"
#include "chsc.h"

/* parameter to enable cmf during boot, possible uses are:
 *  "s390cmf" -- enable cmf and allocate 2 MB of ram so measuring can be
 *               used on any subchannel
 *  "s390cmf=<num>" -- enable cmf and allocate enough memory to measure
 *                     <num> subchannel, where <num> is an integer
 *                     between 1 and 65535, default is 1024
 */
#define ARGSTRING "s390cmf"

/* indices for READCMB */
enum cmb_index {
 /* basic and exended format: */
	cmb_ssch_rsch_count,
	cmb_sample_count,
	cmb_device_connect_time,
	cmb_function_pending_time,
	cmb_device_disconnect_time,
	cmb_control_unit_queuing_time,
	cmb_device_active_only_time,
 /* extended format only: */
	cmb_device_busy_time,
	cmb_initial_command_response_time,
};

/**
 * enum cmb_format - types of supported measurement block formats
 *
 * @CMF_BASIC:      traditional channel measurement blocks supported
 * 		    by all machines that we run on
 * @CMF_EXTENDED:   improved format that was introduced with the z990
 * 		    machine
 * @CMF_AUTODETECT: default: use extended format when running on a z990
 *                  or later machine, otherwise fall back to basic format
 **/
enum cmb_format {
	CMF_BASIC,
	CMF_EXTENDED,
	CMF_AUTODETECT = -1,
};
/**
 * format - actual format for all measurement blocks
 *
 * The format module parameter can be set to a value of 0 (zero)
 * or 1, indicating basic or extended format as described for
 * enum cmb_format.
 */
static int format = CMF_AUTODETECT;
module_param(format, bool, 0444);

/**
 * struct cmb_operations - functions to use depending on cmb_format
 *
 * Most of these functions operate on a struct ccw_device. There is only
 * one instance of struct cmb_operations because the format of the measurement
 * data is guaranteed to be the same for every ccw_device.
 *
 * @alloc:	allocate memory for a channel measurement block,
 *		either with the help of a special pool or with kmalloc
 * @free:	free memory allocated with @alloc
 * @set:	enable or disable measurement
 * @readall:	read a measurement block in a common format
 * @reset:	clear the data in the associated measurement block and
 *		reset its time stamp
 * @align:	align an allocated block so that the hardware can use it
 */
struct cmb_operations {
	int (*alloc)  (struct ccw_device*);
	void(*free)   (struct ccw_device*);
	int (*set)    (struct ccw_device*, u32);
	u64 (*read)   (struct ccw_device*, int);
	int (*readall)(struct ccw_device*, struct cmbdata *);
	void (*reset) (struct ccw_device*);
	void * (*align) (void *);

	struct attribute_group *attr_group;
};
static struct cmb_operations *cmbops;

struct cmb_data {
	void *hw_block;   /* Pointer to block updated by hardware */
	void *last_block; /* Last changed block copied from hardware block */
	int size;	  /* Size of hw_block and last_block */
	unsigned long long last_update;  /* when last_block was updated */
};

/* our user interface is designed in terms of nanoseconds,
 * while the hardware measures total times in its own
 * unit.*/
static inline u64 time_to_nsec(u32 value)
{
	return ((u64)value) * 128000ull;
}

/*
 * Users are usually interested in average times,
 * not accumulated time.
 * This also helps us with atomicity problems
 * when reading sinlge values.
 */
static inline u64 time_to_avg_nsec(u32 value, u32 count)
{
	u64 ret;

	/* no samples yet, avoid division by 0 */
	if (count == 0)
		return 0;