path: root/drivers/s390/cio/cmf.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Linux on zSeries Channel Measurement Facility support
 *
 * Copyright IBM Corp. 2000, 2006
 *
 * Authors: Arnd Bergmann <arndb@de.ibm.com>
 *	    Cornelia Huck <cornelia.huck@de.ibm.com>
 *
 * original idea from Natarajan Krishnaswami <nkrishna@us.ibm.com>
 */

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

#include <linux/memblock.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/export.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/timex.h>	/* get_tod_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 {
	avg_utilization = -1,
 /* basic and exended format: */
	cmb_ssch_rsch_count = 0,
	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 machine
 *		    supporting extended format, 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, bint, 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
 * @read:	read a measurement entry at an index
 * @readall:	read a measurement block in a common format
 * @reset:	clear the data in the associated measurement block and
 *		reset its time stamp
 */
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 *);
/* private: */
	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.
 */<