drivers/s390/cio/css.c - kernel/msm-4.9 - Gitiles

 /*
  *  drivers/s390/cio/css.c
  *  driver for channel subsystem
  *
  *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
  *			 IBM Corporation
  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
  *		 Cornelia Huck (cornelia.huck@de.ibm.com)
  */
 #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 "css.h"
 #include "cio.h"
 #include "cio_debug.h"
 #include "ioasm.h"
 #include "chsc.h"
 #include "device.h"

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

 struct channel_subsystem *css[__MAX_CSSID + 1];

 int css_characteristics_avail = 0;

 inline 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);
 		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);
 	}

 }

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

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

 extern int css_get_ssd_info(struct subchannel *sch);

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

 	/* Initialize the subchannel structure */
 	sch->dev.parent = &css[0]->device;
 	sch->dev.bus = &css_bus_type;
 	sch->dev.release = &css_subchannel_release;

 	/* make it known to the system */
 	ret = device_register(&sch->dev);
 	if (ret)
 		printk (KERN_WARNING "%s: could not register %s\n",
 			__func__, sch->dev.bus_id);
 	else
 		css_get_ssd_info(sch);
 	return ret;
 }

 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,
 			      (void *)&schid, check_subchannel);

 	return dev ? to_subchannel(dev) : NULL;
 }


 static inline int
 css_get_subchannel_status(struct subchannel *sch, struct subchannel_id schid)
 {
 	struct schib schib;
 	int cc;

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

 static int
 css_evaluate_subchannel(struct subchannel_id schid, int slow)
 {
 	int event, ret, disc;
 	struct subchannel *sch;
 	unsigned long flags;

 	sch = get_subchannel_by_schid(schid);
 	disc = sch ? device_is_disconnected(sch) : 0;
 	if (disc && slow) {
 		if (sch)
 			put_device(&sch->dev);
 		return 0; /* Already processed. */
 	}
 	/*
 	 * We've got a machine check, so running I/O won't get an interrupt.
 	 * Kill any pending timers.
 	 */
 	if (sch)
 		device_kill_pending_timer(sch);
 	if (!disc && !slow) {
 		if (sch)
 			put_device(&sch->dev);
 		return -EAGAIN; /* Will be done on the slow path. */
 	}
 	event = css_get_subchannel_status(sch, schid);
 	CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 		      schid.ssid, schid.sch_no, event,
 		      sch?(disc?"disconnected":"normal"):"unknown",
 		      slow?"slow":"fast");
 	switch (event) {
 	case CIO_NO_PATH:
 	case CIO_GONE:
 		if (!sch) {
 			/* Never used this subchannel. Ignore. */
 			ret = 0;
 			break;
 		}
 		if (disc && (event == CIO_NO_PATH)) {
 			/*
 			 * Uargh, hack again. Because we don't get a machine
 			 * check on configure on, our path bookkeeping can
 			 * be out of date here (it's fine while we only do
 			 * logical varying or get chsc machine checks). We
 			 * need to force reprobing or we might miss devices
 			 * coming operational again. It won't do harm in real
 			 * no path situations.
 			 */
 			spin_lock_irqsave(&sch->lock, flags);
 			device_trigger_reprobe(sch);
 			spin_unlock_irqrestore(&sch->lock, flags);
 			ret = 0;
 			break;
 		}
 		if (sch->driver && sch->driver->notify &&
 		    sch->driver->notify(&sch->dev, event)) {
 			cio_disable_subchannel(sch);
 			device_set_disconnected(sch);
 			ret = 0;
 			break;
 		}
 		/*
 		 * Unregister subchannel.
 		 * The device will be killed automatically.
 		 */
 		cio_disable_subchannel(sch);
 		device_unregister(&sch->dev);
 		/* Reset intparm to zeroes. */
 		sch->schib.pmcw.intparm = 0;
 		cio_modify(sch);
 		put_device(&sch->dev);
 		ret = 0;
 		break;
 	case CIO_REVALIDATE:
 		/*
 		 * Revalidation machine check. Sick.
 		 * We don't notify the driver since we have to throw the device
 		 * away in any case.
 		 */
 		if (!disc) {
 			device_unregister(&sch->dev);
 			/* Reset intparm to zeroes. */
 			sch->schib.pmcw.intparm = 0;
 			cio_modify(sch);
 			put_device(&sch->dev);
 			ret = css_probe_device(schid);
 		} else {
 			/*
 			 * We can't immediately deregister the disconnected
 			 * device since it might block.
 			 */
 			spin_lock_irqsave(&sch->lock, flags);
 			device_trigger_reprobe(sch);
 			spin_unlock_irqrestore(&sch->lock, flags);
 			ret = 0;
 		}
 		break;
 	case CIO_OPER:
 		if (disc) {
 			spin_lock_irqsave(&sch->lock, flags);
 			/* Get device operational again. */
 			device_trigger_reprobe(sch);
 			spin_unlock_irqrestore(&sch->lock, flags);
 		}
 		ret = sch ? 0 : css_probe_device(schid);
 		break;
 	default:
 		BUG();
 		ret = 0;
 	}
 	return ret;
 }

 static int
 css_rescan_devices(struct subchannel_id schid, void *data)
 {
 	return css_evaluate_subchannel(schid, 1);
 }

 struct slow_subchannel {
 	struct list_head slow_list;
 	struct subchannel_id schid;
 };

 static LIST_HEAD(slow_subchannels_head);
 static DEFINE_SPINLOCK(slow_subchannel_lock);

 static void
 css_trigger_slow_path(void)
 {
 	CIO_TRACE_EVENT(4, "slowpath");

 	if (need_rescan) {
 		need_rescan = 0;
 		for_each_subchannel(css_rescan_devices, NULL);
 		return;
 	}

 	spin_lock_irq(&slow_subchannel_lock);
 	while (!list_empty(&slow_subchannels_head)) {
 		struct slow_subchannel *slow_sch =
 			list_entry(slow_subchannels_head.next,
 				   struct slow_subchannel, slow_list);

 		list_del_init(slow_subchannels_head.next);
 		spin_unlock_irq(&slow_subchannel_lock);
 		css_evaluate_subchannel(slow_sch->schid, 1);
 		spin_lock_irq(&slow_subchannel_lock);
 		kfree(slow_sch);
 	}
 	spin_unlock_irq(&slow_subchannel_lock);
 }

 typedef void (*workfunc)(void *);
 DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
 struct workqueue_struct *slow_path_wq;

 /* Reprobe subchannel if unregistered. */
 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 {
 	struct subchannel *sch;
 	int ret;

 	CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
 		  schid.ssid, schid.sch_no);
 	if (need_reprobe)
 		return -EAGAIN;

 	sch = get_subchannel_by_schid(schid);
 	if (sch) {
 		/* Already known. */
 		put_device(&sch->dev);
 		return 0;
 	}

 	ret = css_probe_device(schid);
 	switch (ret) {
 	case 0:
 		break;
 	case -ENXIO:
 	case -ENOMEM:
 		/* These should abort looping */
 		break;
 	default:
 		ret = 0;
 	}

 	return ret;
 }

 /* Work function used to reprobe all unregistered subchannels. */
 static void reprobe_all(void *data)
 {
 	int ret;

 	CIO_MSG_EVENT(2, "reprobe start\n");

 	need_reprobe = 0;
 	/* Make sure initial subchannel scan is done. */
 	wait_event(ccw_device_init_wq,
 		   atomic_read(&ccw_device_init_count) == 0);
 	ret = for_each_subchannel(reprobe_subchannel, NULL);

 	CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 		      need_reprobe);
 }

 DECLARE_WORK(css_reprobe_work, reprobe_all, NULL);

 /* Schedule reprobing of all unregistered subchannels. */
 void css_schedule_reprobe(void)
 {
 	need_reprobe = 1;
 	queue_work(ccw_device_work, &css_reprobe_work);
 }

 EXPORT_SYMBOL_GPL(css_schedule_reprobe);

 /*
  * Rescan for new devices. FIXME: This is slow.
  * This function is called when we have lost CRWs due to overflows and we have
  * to do subchannel housekeeping.
  */
 void
 css_reiterate_subchannels(void)
 {
 	css_clear_subchannel_slow_list();
 	need_rescan = 1;
 }

 /*
  * Called from the machine check handler for subchannel report words.
  */
 int
 css_process_crw(int rsid1, int rsid2)
 {
 	int ret;
 	struct subchannel_id mchk_schid;

 	CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 		      rsid1, rsid2);

 	if (need_rescan)
 		/* We need to iterate all subchannels anyway. */
 		return -EAGAIN;

 	init_subchannel_id(&mchk_schid);
 	mchk_schid.sch_no = rsid1;
 	if (rsid2 != 0)
 		mchk_schid.ssid = (rsid2 >> 8) & 3;

 	/*
 	 * Since we are always presented with IPI in the CRW, we have to
 	 * use stsch() to find out if the subchannel in question has come
 	 * or gone.
 	 */
 	ret = css_evaluate_subchannel(mchk_schid, 0);
 	if (ret == -EAGAIN) {
 		if (css_enqueue_subchannel_slow(mchk_schid)) {
 			css_clear_subchannel_slow_list();
 			need_rescan = 1;
 		}
 	}
 	return ret;
 }

 static int __init
 __init_channel_subsystem(struct subchannel_id schid, void *data)
 {
 	struct subchannel *sch;
 	int ret;

 	if (cio_is_console(schid))
 		sch = cio_get_console_subchannel();
 	else {
 		sch = css_alloc_subchannel(schid);
 		if (IS_ERR(sch))
 			ret = PTR_ERR(sch);
 		else
 			ret = 0;
 		switch (ret) {
 		case 0:
 			break;
 		case -ENOMEM:
 			panic("Out of memory in init_channel_subsystem\n");
 		/* -ENXIO: no more subchannels. */
 		case -ENXIO:
 			return ret;
 		/* -EIO: this subchannel set not supported. */
 		case -EIO:
 			return ret;
 		default:
 			return 0;
 		}
 	}
 	/*
 	 * We register ALL valid subchannels in ioinfo, even those
 	 * that have been present before init_channel_subsystem.
 	 * These subchannels can't have been registered yet (kmalloc
 	 * not working) so we do it now. This is true e.g. for the
 	 * console subchannel.
 	 */
 	css_register_subchannel(sch);
 	return 0;
 }

 static void __init
 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 {
 	if (css_characteristics_avail && css_general_characteristics.mcss) {
 		css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 		css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 	} else {
 #ifdef CONFIG_SMP
 		css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 #else
 		css->global_pgid.pgid_high.cpu_addr = 0;
 #endif
 	}
 	css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 	css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 	css->global_pgid.tod_high = tod_high;

 }

 static void
 channel_subsystem_release(struct device *dev)
 {
 	struct channel_subsystem *css;

 	css = to_css(dev);
 	mutex_destroy(&css->mutex);
 	kfree(css);
 }

 static ssize_t
 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 		   char *buf)
 {
 	struct channel_subsystem *css = to_css(dev);

 	if (!css)
 		return 0;
 	return sprintf(buf, "%x\n", css->cm_enabled);
 }

 static ssize_t
 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 		    const char *buf, size_t count)
 {
 	struct channel_subsystem *css = to_css(dev);
 	int ret;

 	switch (buf[0]) {
 	case '0':
 		ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 		break;
 	case '1':
 		ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 		break;
 	default:
 		ret = -EINVAL;
 	}
 	return ret < 0 ? ret : count;
 }

 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);

 static inline void __init
 setup_css(int nr)
 {
 	u32 tod_high;

 	memset(css[nr], 0, sizeof(struct channel_subsystem));
 	mutex_init(&css[nr]->mutex);
 	css[nr]->valid = 1;
 	css[nr]->cssid = nr;
 	sprintf(css[nr]->device.bus_id, "css%x", nr);
 	css[nr]->device.release = channel_subsystem_release;
 	tod_high = (u32) (get_clock() >> 32);
 	css_generate_pgid(css[nr], tod_high);
 }

 /*
  * Now that the driver core is running, we can setup our channel subsystem.
  * The struct subchannel's are created during probing (except for the
  * static console subchannel).
  */
 static int __init
 init_channel_subsystem (void)
 {
 	int ret, i;

 	if (chsc_determine_css_characteristics() == 0)
 		css_characteristics_avail = 1;

 	if ((ret = bus_register(&css_bus_type)))
 		goto out;

 	/* Try to enable MSS. */
 	ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 	switch (ret) {
 	case 0: /* Success. */
 		max_ssid = __MAX_SSID;
 		break;
 	case -ENOMEM:
 		goto out_bus;
 	default:
 		max_ssid = 0;
 	}
 	/* Setup css structure. */
 	for (i = 0; i <= __MAX_CSSID; i++) {
 		css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 		if (!css[i]) {
 			ret = -ENOMEM;
 			goto out_unregister;
 		}
 		setup_css(i);
 		ret = device_register(&css[i]->device);
 		if (ret)
 			goto out_free;
 		if (css_characteristics_avail && css_chsc_characteristics.secm)
 			device_create_file(&css[i]->device,
 					   &dev_attr_cm_enable);
 	}
 	css_init_done = 1;

 	ctl_set_bit(6, 28);

 	for_each_subchannel(__init_channel_subsystem, NULL);
 	return 0;
 out_free:
 	kfree(css[i]);
 out_unregister:
 	while (i > 0) {
 		i--;
 		if (css_characteristics_avail && css_chsc_characteristics.secm)
 			device_remove_file(&css[i]->device,
 					   &dev_attr_cm_enable);
 		device_unregister(&css[i]->device);
 	}
 out_bus:
 	bus_unregister(&css_bus_type);
 out:
 	return ret;
 }

 /*
  * find a driver for a subchannel. They identify by the subchannel
  * type with the exception that the console subchannel driver has its own
  * subchannel type although the device is an i/o subchannel
  */
 static int
 css_bus_match (struct device *dev, struct device_driver *drv)
 {
 	struct subchannel *sch = container_of (dev, struct subchannel, dev);
 	struct css_driver *driver = container_of (drv, struct css_driver, drv);

 	if (sch->st == driver->subchannel_type)
 		return 1;

 	return 0;
 }

 static int
 css_probe (struct device *dev)
 {
 	struct subchannel *sch;

 	sch = to_subchannel(dev);
 	sch->driver = container_of (dev->driver, struct css_driver, drv);
 	return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 }

 static int
 css_remove (struct device *dev)
 {
 	struct subchannel *sch;

 	sch = to_subchannel(dev);
 	return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 }

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

 	sch = to_subchannel(dev);
 	if (sch->driver->shutdown)
 		sch->driver->shutdown(sch);
 }

 struct bus_type css_bus_type = {
 	.name     = "css",
 	.match    = css_bus_match,
 	.probe    = css_probe,
 	.remove   = css_remove,
 	.shutdown = css_shutdown,
 };

 subsys_initcall(init_channel_subsystem);

 int
 css_enqueue_subchannel_slow(struct subchannel_id schid)
 {
 	struct slow_subchannel *new_slow_sch;
 	unsigned long flags;

 	new_slow_sch = kzalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
 	if (!new_slow_sch)
 		return -ENOMEM;
 	new_slow_sch->schid = schid;
 	spin_lock_irqsave(&slow_subchannel_lock, flags);
 	list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
 	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 	return 0;
 }

 void
 css_clear_subchannel_slow_list(void)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&slow_subchannel_lock, flags);
 	while (!list_empty(&slow_subchannels_head)) {
 		struct slow_subchannel *slow_sch =
 			list_entry(slow_subchannels_head.next,
 				   struct slow_subchannel, slow_list);

 		list_del_init(slow_subchannels_head.next);
 		kfree(slow_sch);
 	}
 	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 }


 int
 css_slow_subchannels_exist(void)
 {
 	return (!list_empty(&slow_subchannels_head));
 }

 MODULE_LICENSE("GPL");
 EXPORT_SYMBOL(css_bus_type);
 EXPORT_SYMBOL_GPL(css_characteristics_avail);
	/*
	* drivers/s390/cio/css.c
	* driver for channel subsystem
	*
	* Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
	* IBM Corporation
	* Author(s): Arnd Bergmann (arndb@de.ibm.com)
	* Cornelia Huck (cornelia.huck@de.ibm.com)
	*/
	#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 "css.h"
	#include "cio.h"
	#include "cio_debug.h"
	#include "ioasm.h"
	#include "chsc.h"
	#include "device.h"

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

	struct channel_subsystem *css[__MAX_CSSID + 1];

	int css_characteristics_avail = 0;

	inline 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);
	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);
	}

	}

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

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

	extern int css_get_ssd_info(struct subchannel *sch);

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

	/* Initialize the subchannel structure */
	sch->dev.parent = &css[0]->device;
	sch->dev.bus = &css_bus_type;
	sch->dev.release = &css_subchannel_release;

	/* make it known to the system */
	ret = device_register(&sch->dev);
	if (ret)
	printk (KERN_WARNING "%s: could not register %s\n",
	__func__, sch->dev.bus_id);
	else
	css_get_ssd_info(sch);
	return ret;
	}

	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,
	(void *)&schid, check_subchannel);

	return dev ? to_subchannel(dev) : NULL;
	}


	static inline int
	css_get_subchannel_status(struct subchannel *sch, struct subchannel_id schid)
	{
	struct schib schib;
	int cc;

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

	static int
	css_evaluate_subchannel(struct subchannel_id schid, int slow)
	{
	int event, ret, disc;
	struct subchannel *sch;
	unsigned long flags;

	sch = get_subchannel_by_schid(schid);
	disc = sch ? device_is_disconnected(sch) : 0;
	if (disc && slow) {
	if (sch)
	put_device(&sch->dev);
	return 0; /* Already processed. */
	}
	/*
	* We've got a machine check, so running I/O won't get an interrupt.
	* Kill any pending timers.
	*/
	if (sch)
	device_kill_pending_timer(sch);
	if (!disc && !slow) {
	if (sch)
	put_device(&sch->dev);
	return -EAGAIN; /* Will be done on the slow path. */
	}
	event = css_get_subchannel_status(sch, schid);
	CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
	schid.ssid, schid.sch_no, event,
	sch?(disc?"disconnected":"normal"):"unknown",
	slow?"slow":"fast");
	switch (event) {
	case CIO_NO_PATH:
	case CIO_GONE:
	if (!sch) {
	/* Never used this subchannel. Ignore. */
	ret = 0;
	break;
	}
	if (disc && (event == CIO_NO_PATH)) {
	/*
	* Uargh, hack again. Because we don't get a machine
	* check on configure on, our path bookkeeping can
	* be out of date here (it's fine while we only do
	* logical varying or get chsc machine checks). We
	* need to force reprobing or we might miss devices
	* coming operational again. It won't do harm in real
	* no path situations.
	*/
	spin_lock_irqsave(&sch->lock, flags);
	device_trigger_reprobe(sch);
	spin_unlock_irqrestore(&sch->lock, flags);
	ret = 0;
	break;
	}
	if (sch->driver && sch->driver->notify &&
	sch->driver->notify(&sch->dev, event)) {
	cio_disable_subchannel(sch);
	device_set_disconnected(sch);
	ret = 0;
	break;
	}
	/*
	* Unregister subchannel.
	* The device will be killed automatically.
	*/
	cio_disable_subchannel(sch);
	device_unregister(&sch->dev);
	/* Reset intparm to zeroes. */
	sch->schib.pmcw.intparm = 0;
	cio_modify(sch);
	put_device(&sch->dev);
	ret = 0;
	break;
	case CIO_REVALIDATE:
	/*
	* Revalidation machine check. Sick.
	* We don't notify the driver since we have to throw the device
	* away in any case.
	*/
	if (!disc) {
	device_unregister(&sch->dev);
	/* Reset intparm to zeroes. */
	sch->schib.pmcw.intparm = 0;
	cio_modify(sch);
	put_device(&sch->dev);
	ret = css_probe_device(schid);
	} else {
	/*
	* We can't immediately deregister the disconnected
	* device since it might block.
	*/
	spin_lock_irqsave(&sch->lock, flags);
	device_trigger_reprobe(sch);
	spin_unlock_irqrestore(&sch->lock, flags);
	ret = 0;
	}
	break;
	case CIO_OPER:
	if (disc) {
	spin_lock_irqsave(&sch->lock, flags);
	/* Get device operational again. */
	device_trigger_reprobe(sch);
	spin_unlock_irqrestore(&sch->lock, flags);
	}
	ret = sch ? 0 : css_probe_device(schid);
	break;
	default:
	BUG();
	ret = 0;
	}
	return ret;
	}

	static int
	css_rescan_devices(struct subchannel_id schid, void *data)
	{
	return css_evaluate_subchannel(schid, 1);
	}

	struct slow_subchannel {
	struct list_head slow_list;
	struct subchannel_id schid;
	};

	static LIST_HEAD(slow_subchannels_head);
	static DEFINE_SPINLOCK(slow_subchannel_lock);

	static void
	css_trigger_slow_path(void)
	{
	CIO_TRACE_EVENT(4, "slowpath");

	if (need_rescan) {
	need_rescan = 0;
	for_each_subchannel(css_rescan_devices, NULL);
	return;
	}

	spin_lock_irq(&slow_subchannel_lock);
	while (!list_empty(&slow_subchannels_head)) {
	struct slow_subchannel *slow_sch =
	list_entry(slow_subchannels_head.next,
	struct slow_subchannel, slow_list);

	list_del_init(slow_subchannels_head.next);
	spin_unlock_irq(&slow_subchannel_lock);
	css_evaluate_subchannel(slow_sch->schid, 1);
	spin_lock_irq(&slow_subchannel_lock);
	kfree(slow_sch);
	}
	spin_unlock_irq(&slow_subchannel_lock);
	}

	typedef void (workfunc)(void );
	DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
	struct workqueue_struct *slow_path_wq;

	/* Reprobe subchannel if unregistered. */
	static int reprobe_subchannel(struct subchannel_id schid, void *data)
	{
	struct subchannel *sch;
	int ret;

	CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
	schid.ssid, schid.sch_no);
	if (need_reprobe)
	return -EAGAIN;

	sch = get_subchannel_by_schid(schid);
	if (sch) {
	/* Already known. */
	put_device(&sch->dev);
	return 0;
	}

	ret = css_probe_device(schid);
	switch (ret) {
	case 0:
	break;
	case -ENXIO:
	case -ENOMEM:
	/* These should abort looping */
	break;
	default:
	ret = 0;
	}

	return ret;
	}

	/* Work function used to reprobe all unregistered subchannels. */
	static void reprobe_all(void *data)
	{
	int ret;

	CIO_MSG_EVENT(2, "reprobe start\n");

	need_reprobe = 0;
	/* Make sure initial subchannel scan is done. */
	wait_event(ccw_device_init_wq,
	atomic_read(&ccw_device_init_count) == 0);
	ret = for_each_subchannel(reprobe_subchannel, NULL);

	CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
	need_reprobe);
	}

	DECLARE_WORK(css_reprobe_work, reprobe_all, NULL);

	/* Schedule reprobing of all unregistered subchannels. */
	void css_schedule_reprobe(void)
	{
	need_reprobe = 1;
	queue_work(ccw_device_work, &css_reprobe_work);
	}

	EXPORT_SYMBOL_GPL(css_schedule_reprobe);

	/*
	* Rescan for new devices. FIXME: This is slow.
	* This function is called when we have lost CRWs due to overflows and we have
	* to do subchannel housekeeping.
	*/
	void
	css_reiterate_subchannels(void)
	{
	css_clear_subchannel_slow_list();
	need_rescan = 1;
	}

	/*
	* Called from the machine check handler for subchannel report words.
	*/
	int
	css_process_crw(int rsid1, int rsid2)
	{
	int ret;
	struct subchannel_id mchk_schid;

	CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
	rsid1, rsid2);

	if (need_rescan)
	/* We need to iterate all subchannels anyway. */
	return -EAGAIN;

	init_subchannel_id(&mchk_schid);
	mchk_schid.sch_no = rsid1;
	if (rsid2 != 0)
	mchk_schid.ssid = (rsid2 >> 8) & 3;

	/*
	* Since we are always presented with IPI in the CRW, we have to
	* use stsch() to find out if the subchannel in question has come
	* or gone.
	*/
	ret = css_evaluate_subchannel(mchk_schid, 0);
	if (ret == -EAGAIN) {
	if (css_enqueue_subchannel_slow(mchk_schid)) {
	css_clear_subchannel_slow_list();
	need_rescan = 1;
	}
	}
	return ret;
	}

	static int __init
	__init_channel_subsystem(struct subchannel_id schid, void *data)
	{
	struct subchannel *sch;
	int ret;

	if (cio_is_console(schid))
	sch = cio_get_console_subchannel();
	else {
	sch = css_alloc_subchannel(schid);
	if (IS_ERR(sch))
	ret = PTR_ERR(sch);
	else
	ret = 0;
	switch (ret) {
	case 0:
	break;
	case -ENOMEM:
	panic("Out of memory in init_channel_subsystem\n");
	/* -ENXIO: no more subchannels. */
	case -ENXIO:
	return ret;
	/* -EIO: this subchannel set not supported. */
	case -EIO:
	return ret;
	default:
	return 0;
	}
	}
	/*
	* We register ALL valid subchannels in ioinfo, even those
	* that have been present before init_channel_subsystem.
	* These subchannels can't have been registered yet (kmalloc
	* not working) so we do it now. This is true e.g. for the
	* console subchannel.
	*/
	css_register_subchannel(sch);
	return 0;
	}

	static void __init
	css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
	{
	if (css_characteristics_avail && css_general_characteristics.mcss) {
	css->global_pgid.pgid_high.ext_cssid.version = 0x80;
	css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
	} else {
	#ifdef CONFIG_SMP
	css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
	#else
	css->global_pgid.pgid_high.cpu_addr = 0;
	#endif
	}
	css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
	css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
	css->global_pgid.tod_high = tod_high;

	}

	static void
	channel_subsystem_release(struct device *dev)
	{
	struct channel_subsystem *css;

	css = to_css(dev);
	mutex_destroy(&css->mutex);
	kfree(css);
	}

	static ssize_t
	css_cm_enable_show(struct device dev, struct device_attribute attr,
	char *buf)
	{
	struct channel_subsystem *css = to_css(dev);

	if (!css)
	return 0;
	return sprintf(buf, "%x\n", css->cm_enabled);
	}

	static ssize_t
	css_cm_enable_store(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct channel_subsystem *css = to_css(dev);
	int ret;

	switch (buf[0]) {
	case '0':
	ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
	break;
	case '1':
	ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
	break;
	default:
	ret = -EINVAL;
	}
	return ret < 0 ? ret : count;
	}

	static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);

	static inline void __init
	setup_css(int nr)
	{
	u32 tod_high;

	memset(css[nr], 0, sizeof(struct channel_subsystem));
	mutex_init(&css[nr]->mutex);
	css[nr]->valid = 1;
	css[nr]->cssid = nr;
	sprintf(css[nr]->device.bus_id, "css%x", nr);
	css[nr]->device.release = channel_subsystem_release;
	tod_high = (u32) (get_clock() >> 32);
	css_generate_pgid(css[nr], tod_high);
	}

	/*
	* Now that the driver core is running, we can setup our channel subsystem.
	* The struct subchannel's are created during probing (except for the
	* static console subchannel).
	*/
	static int __init
	init_channel_subsystem (void)
	{
	int ret, i;

	if (chsc_determine_css_characteristics() == 0)
	css_characteristics_avail = 1;

	if ((ret = bus_register(&css_bus_type)))
	goto out;

	/* Try to enable MSS. */
	ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
	switch (ret) {
	case 0: /* Success. */
	max_ssid = __MAX_SSID;
	break;
	case -ENOMEM:
	goto out_bus;
	default:
	max_ssid = 0;
	}
	/* Setup css structure. */
	for (i = 0; i <= __MAX_CSSID; i++) {
	css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
	if (!css[i]) {
	ret = -ENOMEM;
	goto out_unregister;
	}
	setup_css(i);
	ret = device_register(&css[i]->device);
	if (ret)
	goto out_free;
	if (css_characteristics_avail && css_chsc_characteristics.secm)
	device_create_file(&css[i]->device,
	&dev_attr_cm_enable);
	}
	css_init_done = 1;

	ctl_set_bit(6, 28);

	for_each_subchannel(__init_channel_subsystem, NULL);
	return 0;
	out_free:
	kfree(css[i]);
	out_unregister:
	while (i > 0) {
	i--;
	if (css_characteristics_avail && css_chsc_characteristics.secm)
	device_remove_file(&css[i]->device,
	&dev_attr_cm_enable);
	device_unregister(&css[i]->device);
	}
	out_bus:
	bus_unregister(&css_bus_type);
	out:
	return ret;
	}

	/*
	* find a driver for a subchannel. They identify by the subchannel
	* type with the exception that the console subchannel driver has its own
	* subchannel type although the device is an i/o subchannel
	*/
	static int
	css_bus_match (struct device dev, struct device_driver drv)
	{
	struct subchannel *sch = container_of (dev, struct subchannel, dev);
	struct css_driver *driver = container_of (drv, struct css_driver, drv);

	if (sch->st == driver->subchannel_type)
	return 1;

	return 0;
	}

	static int
	css_probe (struct device *dev)
	{
	struct subchannel *sch;

	sch = to_subchannel(dev);
	sch->driver = container_of (dev->driver, struct css_driver, drv);
	return (sch->driver->probe ? sch->driver->probe(sch) : 0);
	}

	static int
	css_remove (struct device *dev)
	{
	struct subchannel *sch;

	sch = to_subchannel(dev);
	return (sch->driver->remove ? sch->driver->remove(sch) : 0);
	}

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

	sch = to_subchannel(dev);
	if (sch->driver->shutdown)
	sch->driver->shutdown(sch);
	}

	struct bus_type css_bus_type = {
	.name = "css",
	.match = css_bus_match,
	.probe = css_probe,
	.remove = css_remove,
	.shutdown = css_shutdown,
	};

	subsys_initcall(init_channel_subsystem);

	int
	css_enqueue_subchannel_slow(struct subchannel_id schid)
	{
	struct slow_subchannel *new_slow_sch;
	unsigned long flags;

	new_slow_sch = kzalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
	if (!new_slow_sch)
	return -ENOMEM;
	new_slow_sch->schid = schid;
	spin_lock_irqsave(&slow_subchannel_lock, flags);
	list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
	return 0;
	}

	void
	css_clear_subchannel_slow_list(void)
	{
	unsigned long flags;

	spin_lock_irqsave(&slow_subchannel_lock, flags);
	while (!list_empty(&slow_subchannels_head)) {
	struct slow_subchannel *slow_sch =
	list_entry(slow_subchannels_head.next,
	struct slow_subchannel, slow_list);

	list_del_init(slow_subchannels_head.next);
	kfree(slow_sch);
	}
	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
	}



	int
	css_slow_subchannels_exist(void)
	{
	return (!list_empty(&slow_subchannels_head));
	}

	MODULE_LICENSE("GPL");
	EXPORT_SYMBOL(css_bus_type);
	EXPORT_SYMBOL_GPL(css_characteristics_avail);