cmf.c

linux 内核源代码

/*
 * linux/drivers/s390/cio/cmf.c
 *
 * Linux on zSeries Channel Measurement Facility support
 *
 * Copyright 2000,2006 IBM Corporation
 *
 * Authors: Arnd Bergmann <[e-mail]>
 *	    Cornelia Huck <[e-mail]>
 *
 * original idea from Natarajan Krishnaswami <[e-mail]>
 *
 * 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 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, 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
 * @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
 * @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 *);
/* 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.
 */
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;

	/* value comes in units of 128 µsec */
	ret = time_to_nsec(value);
	do_div(ret, count);

	return ret;
}

/*
 * Activate or deactivate the channel monitor. When area is NULL,
 * the monitor is deactivated. The channel monitor needs to
 * be active in order to measure subchannels, which also need
 * to be enabled.
 */
static inline void cmf_activate(void *area, unsigned int onoff)
{
	register void * __gpr2 asm("2");
	register long __gpr1 asm("1");

	__gpr2 = area;
	__gpr1 = onoff ? 2 : 0;
	/* activate channel measurement */
	asm("schm" : : "d" (__gpr2), "d" (__gpr1) );
}

static int set_schib(struct ccw_device *cdev, u32 mme, int mbfc,
		     unsigned long address)
{
	int ret;
	int retry;
	struct subchannel *sch;
	struct schib *schib;

	sch = to_subchannel(cdev->dev.parent);
	schib = &sch->schib;
	/* msch can silently fail, so do it again if necessary */
	for (retry = 0; retry < 3; retry++) {
		/* prepare schib */
		stsch(sch->schid, schib);
		schib->pmcw.mme  = mme;
		schib->pmcw.mbfc = mbfc;
		/* address can be either a block address or a block index */
		if (mbfc)
			schib->mba = address;
		else
			schib->pmcw.mbi = address;

		/* try to submit it */
		switch(ret = msch_err(sch->schid, schib)) {
			case 0:
				break;
			case 1:
			case 2: /* in I/O or status pending */
				ret = -EBUSY;
				break;
			case 3: /* subchannel is no longer valid */
				ret = -ENODEV;
				break;
			default: /* msch caught an exception */
				ret = -EINVAL;
				break;
		}
		stsch(sch->schid, schib); /* restore the schib */

		if (ret)
			break;

		/* check if it worked */
		if (schib->pmcw.mme  == mme &&
		    schib->pmcw.mbfc == mbfc &&
		    (mbfc ? (schib->mba == address)
			  : (schib->pmcw.mbi == address)))
			return 0;

		ret = -EINVAL;
	}

	return ret;
}

struct set_schib_struct {
	u32 mme;
	int mbfc;
	unsigned long address;
	wait_queue_head_t wait;
	int ret;
	struct kref kref;
};

static void cmf_set_schib_release(struct kref *kref)
{
	struct set_schib_struct *set_data;

	set_data = container_of(kref, struct set_schib_struct, kref);
	kfree(set_data);
}

#define CMF_PENDING 1

static int set_schib_wait(struct ccw_device *cdev, u32 mme,
				int mbfc, unsigned long address)
{
	struct set_schib_struct *set_data;
	int ret;

	spin_lock_irq(cdev->ccwlock);
	if (!cdev->private->cmb) {
		ret = -ENODEV;
		goto out;
	}
	set_data = kzalloc(sizeof(struct set_schib_struct), GFP_ATOMIC);
	if (!set_data) {
		ret = -ENOMEM;
		goto out;
	}
	init_waitqueue_head(&set_data->wait);
	kref_init(&set_data->kref);
	set_data->mme = mme;
	set_data->mbfc = mbfc;
	set_data->address = address;

	ret = set_schib(cdev, mme, mbfc, address);
	if (ret != -EBUSY)
		goto out_put;

	if (cdev->private->state != DEV_STATE_ONLINE) {
		/* if the device is not online, don't even try again */
		ret = -EBUSY;
		goto out_put;
	}

	cdev->private->state = DEV_STATE_CMFCHANGE;
	set_data->ret = CMF_PENDING;
	cdev->private->cmb_wait = set_data;

	spin_unlock_irq(cdev->ccwlock);
	if (wait_event_interruptible(set_data->wait,
				     set_data->ret != CMF_PENDING)) {
		spin_lock_irq(cdev->ccwlock);
		if (set_data->ret == CMF_PENDING) {
			set_data->ret = -ERESTARTSYS;
			if (cdev->private->state == DEV_STATE_CMFCHANGE)
				cdev->private->state = DEV_STATE_ONLINE;
		}
		spin_unlock_irq(cdev->ccwlock);
	}
	spin_lock_irq(cdev->ccwlock);
	cdev->private->cmb_wait = NULL;
	ret = set_data->ret;
out_put:
	kref_put(&set_data->kref, cmf_set_schib_release);
out:
	spin_unlock_irq(cdev->ccwlock);
	return ret;
}

void retry_set_schib(struct ccw_device *cdev)
{
	struct set_schib_struct *set_data;

	set_data = cdev->private->cmb_wait;
	if (!set_data) {
		WARN_ON(1);
		return;
	}
	kref_get(&set_data->kref);
	set_data->ret = set_schib(cdev, set_data->mme, set_data->mbfc,
				  set_data->address);
	wake_up(&set_data->wait);
	kref_put(&set_data->kref, cmf_set_schib_release);
}

static int cmf_copy_block(struct ccw_device *cdev)
{
	struct subchannel *sch;
	void *reference_buf;
	void *hw_block;
	struct cmb_data *cmb_data;

	sch = to_subchannel(cdev->dev.parent);

	if (stsch(sch->schid, &sch->schib))
		return -ENODEV;

	if (sch->schib.scsw.fctl & SCSW_FCTL_START_FUNC) {
		/* Don't copy if a start function is in progress. */
		if ((!(sch->schib.scsw.actl & SCSW_ACTL_SUSPENDED)) &&
		    (sch->schib.scsw.actl &
		     (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT)) &&
		    (!(sch->schib.scsw.stctl & SCSW_STCTL_SEC_STATUS)))
			return -EBUSY;
	}
	cmb_data = cdev->private->cmb;
	hw_block = cmbops->align(cmb_data->hw_block);
	if (!memcmp(cmb_data->last_block, hw_block, cmb_data->size))
		/* No need to copy. */
		return 0;
	reference_buf = kzalloc(cmb_data->size, GFP_ATOMIC);
	if (!reference_buf)
		return -ENOMEM;
	/* Ensure consistency of block copied from hardware. */
	do {
		memcpy(cmb_data->last_block, hw_block, cmb_data->size);
		memcpy(reference_buf, hw_block, cmb_data->size);
	} while (memcmp(cmb_data->last_block, reference_buf, cmb_data->size));
	cmb_data->last_update = get_clock();
	kfree(reference_buf);
	return 0;
}

struct copy_block_struct {
	wait_queue_head_t wait;
	int ret;
	struct kref kref;
};

static void cmf_copy_block_release(struct kref *kref)
{
	struct copy_block_struct *copy_block;

	copy_block = container_of(kref, struct copy_block_struct, kref);
	kfree(copy_block);
}

static int cmf_cmb_copy_wait(struct ccw_device *cdev)
{
	struct copy_block_struct *copy_block;
	int ret;
	unsigned long flags;

	spin_lock_irqsave(cdev->ccwlock, flags);
	if (!cdev->private->cmb) {
		ret = -ENODEV;
		goto out;
	}
	copy_block = kzalloc(sizeof(struct copy_block_struct), GFP_ATOMIC);
	if (!copy_block) {
		ret = -ENOMEM;
		goto out;
	}
	init_waitqueue_head(&copy_block->wait);
	kref_init(&copy_block->kref);

	ret = cmf_copy_block(cdev);
	if (ret != -EBUSY)
		goto out_put;

	if (cdev->private->state != DEV_STATE_ONLINE) {
		ret = -EBUSY;
		goto out_put;
	}

	cdev->private->state = DEV_STATE_CMFUPDATE;
	copy_block->ret = CMF_PENDING;
	cdev->private->cmb_wait = copy_block;

	spin_unlock_irqrestore(cdev->ccwlock, flags);
	if (wait_event_interruptible(copy_block->wait,
				     copy_block->ret != CMF_PENDING)) {
		spin_lock_irqsave(cdev->ccwlock, flags);
		if (copy_block->ret == CMF_PENDING) {
			copy_block->ret = -ERESTARTSYS;
			if (cdev->private->state == DEV_STATE_CMFUPDATE)
				cdev->private->state = DEV_STATE_ONLINE;
		}
		spin_unlock_irqrestore(cdev->ccwlock, flags);
	}
	spin_lock_irqsave(cdev->ccwlock, flags);
	cdev->private->cmb_wait = NULL;
	ret = copy_block->ret;
out_put:
	kref_put(&copy_block->kref, cmf_copy_block_release);
out:
	spin_unlock_irqrestore(cdev->ccwlock, flags);
	return ret;
}

void cmf_retry_copy_block(struct ccw_device *cdev)
{
	struct copy_block_struct *copy_block;

	copy_block = cdev->private->cmb_wait;
	if (!copy_block) {
		WARN_ON(1);
		return;
	}
	kref_get(&copy_block->kref);
	copy_block->ret = cmf_copy_block(cdev);
	wake_up(&copy_block->wait);
	kref_put(&copy_block->kref, cmf_copy_block_release);
}

static void cmf_generic_reset(struct ccw_device *cdev)
{
	struct cmb_data *cmb_data;

	spin_lock_irq(cdev->ccwlock);
	cmb_data = cdev->private->cmb;
	if (cmb_data) {
		memset(cmb_data->last_block, 0, cmb_data->size);
		/*
		 * Need to reset hw block as well to make the hardware start
		 * from 0 again.