css.c

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/*
 *  drivers/s390/cio/css.c
 *  driver for channel subsystem
 *
 *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
 *			 IBM Corporation
 *    Author(s): Arnd Bergmann ([e-mail])
 *		 Cornelia Huck ([e-mail])
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/reboot.h>

#include "css.h"
#include "cio.h"
#include "cio_debug.h"
#include "ioasm.h"
#include "chsc.h"
#include "device.h"
#include "idset.h"
#include "chp.h"

int css_init_done = 0;
static int need_reprobe = 0;
static int max_ssid = 0;

struct channel_subsystem *channel_subsystems[__MAX_CSSID + 1];

int css_characteristics_avail = 0;

int
for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
{
	struct subchannel_id schid;
	int ret;

	init_subchannel_id(&schid);
	ret = -ENODEV;
	do {
		do {
			ret = fn(schid, data);
			if (ret)
				break;
		} while (schid.sch_no++ < __MAX_SUBCHANNEL);
		schid.sch_no = 0;
	} while (schid.ssid++ < max_ssid);
	return ret;
}

static struct subchannel *
css_alloc_subchannel(struct subchannel_id schid)
{
	struct subchannel *sch;
	int ret;

	sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
	if (sch == NULL)
		return ERR_PTR(-ENOMEM);
	ret = cio_validate_subchannel (sch, schid);
	if (ret < 0) {
		kfree(sch);
		return ERR_PTR(ret);
	}

	if (sch->st != SUBCHANNEL_TYPE_IO) {
		/* For now we ignore all non-io subchannels. */
		kfree(sch);
		return ERR_PTR(-EINVAL);
	}

	/* 
	 * Set intparm to subchannel address.
	 * This is fine even on 64bit since the subchannel is always located
	 * under 2G.
	 */
	sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
	ret = cio_modify(sch);
	if (ret) {
		kfree(sch->lock);
		kfree(sch);
		return ERR_PTR(ret);
	}
	return sch;
}

static void
css_free_subchannel(struct subchannel *sch)
{
	if (sch) {
		/* Reset intparm to zeroes. */
		sch->schib.pmcw.intparm = 0;
		cio_modify(sch);
		kfree(sch->lock);
		kfree(sch);
	}
}

static void
css_subchannel_release(struct device *dev)
{
	struct subchannel *sch;

	sch = to_subchannel(dev);
	if (!cio_is_console(sch->schid)) {
		kfree(sch->lock);
		kfree(sch);
	}
}

static int css_sch_device_register(struct subchannel *sch)
{
	int ret;

	mutex_lock(&sch->reg_mutex);
	ret = device_register(&sch->dev);
	mutex_unlock(&sch->reg_mutex);
	return ret;
}

void css_sch_device_unregister(struct subchannel *sch)
{
	mutex_lock(&sch->reg_mutex);
	device_unregister(&sch->dev);
	mutex_unlock(&sch->reg_mutex);
}

static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)
{
	int i;
	int mask;

	memset(ssd, 0, sizeof(struct chsc_ssd_info));
	ssd->path_mask = pmcw->pim;
	for (i = 0; i < 8; i++) {
		mask = 0x80 >> i;
		if (pmcw->pim & mask) {
			chp_id_init(&ssd->chpid[i]);
			ssd->chpid[i].id = pmcw->chpid[i];
		}
	}
}

static void ssd_register_chpids(struct chsc_ssd_info *ssd)
{
	int i;
	int mask;

	for (i = 0; i < 8; i++) {
		mask = 0x80 >> i;
		if (ssd->path_mask & mask)
			if (!chp_is_registered(ssd->chpid[i]))
				chp_new(ssd->chpid[i]);
	}
}

void css_update_ssd_info(struct subchannel *sch)
{
	int ret;

	if (cio_is_console(sch->schid)) {
		/* Console is initialized too early for functions requiring
		 * memory allocation. */
		ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
	} else {
		ret = chsc_get_ssd_info(sch->schid, &sch->ssd_info);
		if (ret)
			ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
		ssd_register_chpids(&sch->ssd_info);
	}
}

static int css_register_subchannel(struct subchannel *sch)
{
	int ret;

	/* Initialize the subchannel structure */
	sch->dev.parent = &channel_subsystems[0]->device;
	sch->dev.bus = &css_bus_type;
	sch->dev.release = &css_subchannel_release;
	sch->dev.groups = subch_attr_groups;
	/*
	 * We don't want to generate uevents for I/O subchannels that don't
	 * have a working ccw device behind them since they will be
	 * unregistered before they can be used anyway, so we delay the add
	 * uevent until after device recognition was successful.
	 */
	if (!cio_is_console(sch->schid))
		/* Console is special, no need to suppress. */
		sch->dev.uevent_suppress = 1;
	css_update_ssd_info(sch);
	/* make it known to the system */
	ret = css_sch_device_register(sch);
	if (ret) {
		CIO_MSG_EVENT(0, "Could not register sch 0.%x.%04x: %d\n",
			      sch->schid.ssid, sch->schid.sch_no, ret);
		return ret;
	}
	return ret;
}

static int css_probe_device(struct subchannel_id schid)
{
	int ret;
	struct subchannel *sch;

	sch = css_alloc_subchannel(schid);
	if (IS_ERR(sch))
		return PTR_ERR(sch);
	ret = css_register_subchannel(sch);
	if (ret)
		css_free_subchannel(sch);
	return ret;
}

static int
check_subchannel(struct device * dev, void * data)
{
	struct subchannel *sch;
	struct subchannel_id *schid = data;

	sch = to_subchannel(dev);
	return schid_equal(&sch->schid, schid);
}

struct subchannel *
get_subchannel_by_schid(struct subchannel_id schid)
{
	struct device *dev;

	dev = bus_find_device(&css_bus_type, NULL,
			      &schid, check_subchannel);

	return dev ? to_subchannel(dev) : NULL;
}

static int css_get_subchannel_status(struct subchannel *sch)
{
	struct schib schib;

	if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
		return CIO_GONE;
	if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
		return CIO_REVALIDATE;
	if (!sch->lpm)
		return CIO_NO_PATH;
	return CIO_OPER;
}

static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
{
	int event, ret, disc;
	unsigned long flags;
	enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;

	spin_lock_irqsave(sch->lock, flags);
	disc = device_is_disconnected(sch);
	if (disc && slow) {
		/* Disconnected devices are evaluated directly only.*/
		spin_unlock_irqrestore(sch->lock, flags);
		return 0;
	}
	/* No interrupt after machine check - kill pending timers. */
	device_kill_pending_timer(sch);
	if (!disc && !slow) {
		/* Non-disconnected devices are evaluated on the slow path. */
		spin_unlock_irqrestore(sch->lock, flags);
		return -EAGAIN;
	}
	event = css_get_subchannel_status(sch);
	CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
		      sch->schid.ssid, sch->schid.sch_no, event,
		      disc ? "disconnected" : "normal",
		      slow ? "slow" : "fast");
	/* Analyze subchannel status. */
	action = NONE;
	switch (event) {
	case CIO_NO_PATH:
		if (disc) {
			/* Check if paths have become available. */
			action = REPROBE;
			break;
		}
		/* fall through */
	case CIO_GONE:
		/* Prevent unwanted effects when opening lock. */
		cio_disable_subchannel(sch);
		device_set_disconnected(sch);
		/* Ask driver what to do with device. */
		action = UNREGISTER;
		if (sch->driver && sch->driver->notify) {
			spin_unlock_irqrestore(sch->lock, flags);
			ret = sch->driver->notify(&sch->dev, event);
			spin_lock_irqsave(sch->lock, flags);
			if (ret)
				action = NONE;
		}
		break;
	case CIO_REVALIDATE:
		/* Device will be removed, so no notify necessary. */
		if (disc)
			/* Reprobe because immediate unregister might block. */
			action = REPROBE;
		else
			action = UNREGISTER_PROBE;
		break;
	case CIO_OPER:
		if (disc)
			/* Get device operational again. */
			action = REPROBE;
		break;
	}
	/* Perform action. */
	ret = 0;
	switch (action) {
	case UNREGISTER:
	case UNREGISTER_PROBE:
		/* Unregister device (will use subchannel lock). */
		spin_unlock_irqrestore(sch->lock, flags);
		css_sch_device_unregister(sch);
		spin_lock_irqsave(sch->lock, flags);

		/* Reset intparm to zeroes. */
		sch->schib.pmcw.intparm = 0;
		cio_modify(sch);
		break;
	case REPROBE:
		device_trigger_reprobe(sch);
		break;
	default:
		break;
	}
	spin_unlock_irqrestore(sch->lock, flags);
	/* Probe if necessary. */
	if (action == UNREGISTER_PROBE)
		ret = css_probe_device(sch->schid);

	return ret;
}

static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
{
	struct schib schib;

	if (!slow) {
		/* Will be done on the slow path. */
		return -EAGAIN;
	}
	if (stsch_err(schid, &schib) || !schib.pmcw.dnv) {
		/* Unusable - ignore. */
		return 0;
	}
	CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
			 "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);

	return css_probe_device(schid);
}

static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
{
	struct subchannel *sch;
	int ret;

	sch = get_subchannel_by_schid(schid);
	if (sch) {
		ret = css_evaluate_known_subchannel(sch, slow);
		put_device(&sch->dev);
	} else
		ret = css_evaluate_new_subchannel(schid, slow);
	if (ret == -EAGAIN)
		css_schedule_eval(schid);
}

static struct idset *slow_subchannel_set;
static spinlock_t slow_subchannel_lock;

static int __init slow_subchannel_init(void)
{
	spin_lock_init(&slow_subchannel_lock);
	slow_subchannel_set = idset_sch_new();
	if (!slow_subchannel_set) {
		CIO_MSG_EVENT(0, "could not allocate slow subchannel set\n");
		return -ENOMEM;
	}
	return 0;
}

static void css_slow_path_func(struct work_struct *unused)
{
	struct subchannel_id schid;

	CIO_TRACE_EVENT(4, "slowpath");
	spin_lock_irq(&slow_subchannel_lock);
	init_subchannel_id(&schid);
	while (idset_sch_get_first(slow_subchannel_set, &schid)) {
		idset_sch_del(slow_subchannel_set, schid);
		spin_unlock_irq(&slow_subchannel_lock);
		css_evaluate_subchannel(schid, 1);
		spin_lock_irq(&slow_subchannel_lock);
	}
	spin_unlock_irq(&slow_subchannel_lock);
}

static DECLARE_WORK(slow_path_work, css_slow_path_func);
struct workqueue_struct *slow_path_wq;

void css_schedule_eval(struct subchannel_id schid)
{
	unsigned long flags;

	spin_lock_irqsave(&slow_subchannel_lock, flags);
	idset_sch_add(slow_subchannel_set, schid);
	queue_work(slow_path_wq, &slow_path_work);
	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
}

void css_schedule_eval_all(void)
{