[deliverable/linux.git] / drivers / s390 / cio / css.c

/*
 *  drivers/s390/cio/css.c
 *  driver for channel subsystem
 *   $Revision: 1.93 $
 *
 *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
 *			 IBM Corporation
 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *		 Cornelia Huck (cohuck@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"

int need_rescan = 0;
int css_init_done = 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;

/*
 * 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;
		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);
	kfree(css);
}

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

	memset(css[nr], 0, sizeof(struct channel_subsystem));
	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;
	}
	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--;
		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;
}

struct bus_type css_bus_type = {
	.name  = "css",
	.match = &css_bus_match,
};

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 = kmalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
	if (!new_slow_sch)
		return -ENOMEM;
	memset(new_slow_sch, 0, sizeof(struct slow_subchannel));
	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);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* drivers/s390/cio/css.c
	3	* driver for channel subsystem
fb6958a5	4	* $Revision: 1.93 $
1da177e4 LT	5	*
	6	* Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
	7	* IBM Corporation
	8	* Author(s): Arnd Bergmann (arndb@de.ibm.com)
	9	* Cornelia Huck (cohuck@de.ibm.com)
	10	*/
	11	#include <linux/module.h>
	12	#include <linux/init.h>
	13	#include <linux/device.h>
	14	#include <linux/slab.h>
	15	#include <linux/errno.h>
	16	#include <linux/list.h>
	17
	18	#include "css.h"
	19	#include "cio.h"
	20	#include "cio_debug.h"
	21	#include "ioasm.h"
	22	#include "chsc.h"
	23
1da177e4 LT	24	int need_rescan = 0;
1da177e4 LT	25	int css_init_done = 0;
fb6958a5	26	static int max_ssid = 0;
1da177e4	27
a28c6944	28	struct channel_subsystem *css[__MAX_CSSID + 1];
1da177e4	29
a28c6944	30	int css_characteristics_avail = 0;
1da177e4	31
f97a56fb CH	32	inline int
	33	for_each_subchannel(int(fn)(struct subchannel_id, void ), void *data)
	34	{
	35	struct subchannel_id schid;
	36	int ret;
	37
	38	init_subchannel_id(&schid);
	39	ret = -ENODEV;
	40	do {
fb6958a5 CH	41	do {
	42	ret = fn(schid, data);
	43	if (ret)
	44	break;
	45	} while (schid.sch_no++ < __MAX_SUBCHANNEL);
	46	schid.sch_no = 0;
	47	} while (schid.ssid++ < max_ssid);
f97a56fb CH	48	return ret;
	49	}
	50
1da177e4	51	static struct subchannel *
a8237fc4	52	css_alloc_subchannel(struct subchannel_id schid)
1da177e4 LT	53	{
	54	struct subchannel *sch;
	55	int ret;
	56
	57	sch = kmalloc (sizeof (*sch), GFP_KERNEL \| GFP_DMA);
	58	if (sch == NULL)
	59	return ERR_PTR(-ENOMEM);
a8237fc4	60	ret = cio_validate_subchannel (sch, schid);
1da177e4 LT	61	if (ret < 0) {
	62	kfree(sch);
	63	return ERR_PTR(ret);
	64	}
1da177e4 LT	65
	66	if (sch->st != SUBCHANNEL_TYPE_IO) {
	67	/* For now we ignore all non-io subchannels. */
	68	kfree(sch);
	69	return ERR_PTR(-EINVAL);
	70	}
	71
	72	/*
	73	* Set intparm to subchannel address.
	74	* This is fine even on 64bit since the subchannel is always located
	75	* under 2G.
	76	*/
	77	sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
	78	ret = cio_modify(sch);
	79	if (ret) {
	80	kfree(sch);
	81	return ERR_PTR(ret);
	82	}
	83	return sch;
	84	}
	85
	86	static void
	87	css_free_subchannel(struct subchannel *sch)
	88	{
	89	if (sch) {
	90	/* Reset intparm to zeroes. */
	91	sch->schib.pmcw.intparm = 0;
	92	cio_modify(sch);
	93	kfree(sch);
	94	}
	95
	96	}
	97
	98	static void
	99	css_subchannel_release(struct device *dev)
	100	{
	101	struct subchannel *sch;
	102
	103	sch = to_subchannel(dev);
a8237fc4	104	if (!cio_is_console(sch->schid))
1da177e4 LT	105	kfree(sch);
	106	}
	107
	108	extern int css_get_ssd_info(struct subchannel *sch);
	109
	110	static int
	111	css_register_subchannel(struct subchannel *sch)
	112	{
	113	int ret;
	114
	115	/* Initialize the subchannel structure */
a28c6944	116	sch->dev.parent = &css[0]->device;
1da177e4 LT	117	sch->dev.bus = &css_bus_type;
	118	sch->dev.release = &css_subchannel_release;
	119
	120	/* make it known to the system */
	121	ret = device_register(&sch->dev);
	122	if (ret)
	123	printk (KERN_WARNING "%s: could not register %s\n",
	124	__func__, sch->dev.bus_id);
	125	else
	126	css_get_ssd_info(sch);
	127	return ret;
	128	}
	129
	130	int
a8237fc4	131	css_probe_device(struct subchannel_id schid)
1da177e4 LT	132	{
	133	int ret;
	134	struct subchannel *sch;
	135
a8237fc4	136	sch = css_alloc_subchannel(schid);
1da177e4 LT	137	if (IS_ERR(sch))
	138	return PTR_ERR(sch);
	139	ret = css_register_subchannel(sch);
	140	if (ret)
	141	css_free_subchannel(sch);
	142	return ret;
	143	}
	144
b0744bd2 CH	145	static int
	146	check_subchannel(struct device * dev, void * data)
	147	{
	148	struct subchannel *sch;
a8237fc4	149	struct subchannel_id *schid = data;
b0744bd2 CH	150
b0744bd2 CH	151	sch = to_subchannel(dev);
a8237fc4	152	return schid_equal(&sch->schid, schid);
b0744bd2 CH	153	}
b0744bd2 CH	154
1da177e4	155	struct subchannel *
a8237fc4	156	get_subchannel_by_schid(struct subchannel_id schid)
1da177e4	157	{
1da177e4 LT	158	struct device *dev;
1da177e4 LT	159
b0744bd2	160	dev = bus_find_device(&css_bus_type, NULL,
a8237fc4	161	(void *)&schid, check_subchannel);
1da177e4	162
b0744bd2	163	return dev ? to_subchannel(dev) : NULL;
1da177e4 LT	164	}
1da177e4 LT	165
b0744bd2	166
1da177e4	167	static inline int
a8237fc4	168	css_get_subchannel_status(struct subchannel *sch, struct subchannel_id schid)
1da177e4 LT	169	{
	170	struct schib schib;
	171	int cc;
	172
	173	cc = stsch(schid, &schib);
	174	if (cc)
	175	return CIO_GONE;
	176	if (!schib.pmcw.dnv)
	177	return CIO_GONE;
	178	if (sch && sch->schib.pmcw.dnv &&
	179	(schib.pmcw.dev != sch->schib.pmcw.dev))
	180	return CIO_REVALIDATE;
	181	if (sch && !sch->lpm)
	182	return CIO_NO_PATH;
	183	return CIO_OPER;
	184	}
	185
	186	static int
a8237fc4	187	css_evaluate_subchannel(struct subchannel_id schid, int slow)
1da177e4 LT	188	{
	189	int event, ret, disc;
	190	struct subchannel *sch;
	191	unsigned long flags;
	192
a8237fc4	193	sch = get_subchannel_by_schid(schid);
1da177e4 LT	194	disc = sch ? device_is_disconnected(sch) : 0;
	195	if (disc && slow) {
	196	if (sch)
	197	put_device(&sch->dev);
	198	return 0; /* Already processed. */
	199	}
	200	/*
	201	* We've got a machine check, so running I/O won't get an interrupt.
	202	* Kill any pending timers.
	203	*/
	204	if (sch)
	205	device_kill_pending_timer(sch);
	206	if (!disc && !slow) {
	207	if (sch)
	208	put_device(&sch->dev);
	209	return -EAGAIN; /* Will be done on the slow path. */
	210	}
a8237fc4	211	event = css_get_subchannel_status(sch, schid);
fb6958a5 CH	212	CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
fb6958a5 CH	213	schid.ssid, schid.sch_no, event,
a8237fc4	214	sch?(disc?"disconnected":"normal"):"unknown",
1da177e4 LT	215	slow?"slow":"fast");
	216	switch (event) {
	217	case CIO_NO_PATH:
	218	case CIO_GONE:
	219	if (!sch) {
	220	/* Never used this subchannel. Ignore. */
	221	ret = 0;
	222	break;
	223	}
	224	if (disc && (event == CIO_NO_PATH)) {
	225	/*
	226	* Uargh, hack again. Because we don't get a machine
	227	* check on configure on, our path bookkeeping can
	228	* be out of date here (it's fine while we only do
	229	* logical varying or get chsc machine checks). We
	230	* need to force reprobing or we might miss devices
	231	* coming operational again. It won't do harm in real
	232	* no path situations.
	233	*/
	234	spin_lock_irqsave(&sch->lock, flags);
	235	device_trigger_reprobe(sch);
	236	spin_unlock_irqrestore(&sch->lock, flags);
	237	ret = 0;
	238	break;
	239	}
	240	if (sch->driver && sch->driver->notify &&
	241	sch->driver->notify(&sch->dev, event)) {
	242	cio_disable_subchannel(sch);
	243	device_set_disconnected(sch);
	244	ret = 0;
	245	break;
	246	}
	247	/*
	248	* Unregister subchannel.
	249	* The device will be killed automatically.
	250	*/
	251	cio_disable_subchannel(sch);
	252	device_unregister(&sch->dev);
	253	/* Reset intparm to zeroes. */
	254	sch->schib.pmcw.intparm = 0;
	255	cio_modify(sch);
	256	put_device(&sch->dev);
	257	ret = 0;
	258	break;
	259	case CIO_REVALIDATE:
	260	/*
	261	* Revalidation machine check. Sick.
	262	* We don't notify the driver since we have to throw the device
	263	* away in any case.
	264	*/
	265	if (!disc) {
	266	device_unregister(&sch->dev);
	267	/* Reset intparm to zeroes. */
	268	sch->schib.pmcw.intparm = 0;
	269	cio_modify(sch);
	270	put_device(&sch->dev);
a8237fc4	271	ret = css_probe_device(schid);
1da177e4 LT	272	} else {
	273	/*
	274	* We can't immediately deregister the disconnected
	275	* device since it might block.
	276	*/
	277	spin_lock_irqsave(&sch->lock, flags);
	278	device_trigger_reprobe(sch);
	279	spin_unlock_irqrestore(&sch->lock, flags);
	280	ret = 0;
	281	}
	282	break;
	283	case CIO_OPER:
	284	if (disc) {
	285	spin_lock_irqsave(&sch->lock, flags);
	286	/* Get device operational again. */
	287	device_trigger_reprobe(sch);
	288	spin_unlock_irqrestore(&sch->lock, flags);
	289	}
a8237fc4	290	ret = sch ? 0 : css_probe_device(schid);
1da177e4 LT	291	break;
	292	default:
	293	BUG();
	294	ret = 0;
	295	}
	296	return ret;
	297	}
	298
f97a56fb CH	299	static int
f97a56fb CH	300	css_rescan_devices(struct subchannel_id schid, void *data)
1da177e4	301	{
f97a56fb	302	return css_evaluate_subchannel(schid, 1);
1da177e4 LT	303	}
	304
	305	struct slow_subchannel {
	306	struct list_head slow_list;
a8237fc4	307	struct subchannel_id schid;
1da177e4 LT	308	};
	309
	310	static LIST_HEAD(slow_subchannels_head);
	311	static DEFINE_SPINLOCK(slow_subchannel_lock);
	312
	313	static void
	314	css_trigger_slow_path(void)
	315	{
	316	CIO_TRACE_EVENT(4, "slowpath");
	317
	318	if (need_rescan) {
	319	need_rescan = 0;
f97a56fb	320	for_each_subchannel(css_rescan_devices, NULL);
1da177e4 LT	321	return;
	322	}
	323
	324	spin_lock_irq(&slow_subchannel_lock);
	325	while (!list_empty(&slow_subchannels_head)) {
	326	struct slow_subchannel *slow_sch =
	327	list_entry(slow_subchannels_head.next,
	328	struct slow_subchannel, slow_list);
	329
	330	list_del_init(slow_subchannels_head.next);
	331	spin_unlock_irq(&slow_subchannel_lock);
	332	css_evaluate_subchannel(slow_sch->schid, 1);
	333	spin_lock_irq(&slow_subchannel_lock);
	334	kfree(slow_sch);
	335	}
	336	spin_unlock_irq(&slow_subchannel_lock);
	337	}
	338
	339	typedef void (workfunc)(void );
	340	DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
	341	struct workqueue_struct *slow_path_wq;
	342
	343	/*
	344	* Rescan for new devices. FIXME: This is slow.
	345	* This function is called when we have lost CRWs due to overflows and we have
	346	* to do subchannel housekeeping.
	347	*/
	348	void
	349	css_reiterate_subchannels(void)
	350	{
	351	css_clear_subchannel_slow_list();
	352	need_rescan = 1;
	353	}
	354
	355	/*
	356	* Called from the machine check handler for subchannel report words.
	357	*/
	358	int
fb6958a5	359	css_process_crw(int rsid1, int rsid2)
1da177e4 LT	360	{
1da177e4 LT	361	int ret;
a8237fc4	362	struct subchannel_id mchk_schid;
1da177e4	363
fb6958a5 CH	364	CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
fb6958a5 CH	365	rsid1, rsid2);
1da177e4 LT	366
	367	if (need_rescan)
	368	/* We need to iterate all subchannels anyway. */
	369	return -EAGAIN;
a8237fc4 CH	370
a8237fc4 CH	371	init_subchannel_id(&mchk_schid);
fb6958a5 CH	372	mchk_schid.sch_no = rsid1;
	373	if (rsid2 != 0)
	374	mchk_schid.ssid = (rsid2 >> 8) & 3;
	375
1da177e4 LT	376	/*
	377	* Since we are always presented with IPI in the CRW, we have to
	378	* use stsch() to find out if the subchannel in question has come
	379	* or gone.
	380	*/
a8237fc4	381	ret = css_evaluate_subchannel(mchk_schid, 0);
1da177e4	382	if (ret == -EAGAIN) {
a8237fc4	383	if (css_enqueue_subchannel_slow(mchk_schid)) {
1da177e4 LT	384	css_clear_subchannel_slow_list();
	385	need_rescan = 1;
	386	}
	387	}
	388	return ret;
	389	}
	390
f97a56fb CH	391	static int __init
	392	__init_channel_subsystem(struct subchannel_id schid, void *data)
	393	{
	394	struct subchannel *sch;
	395	int ret;
	396
	397	if (cio_is_console(schid))
	398	sch = cio_get_console_subchannel();
	399	else {
	400	sch = css_alloc_subchannel(schid);
	401	if (IS_ERR(sch))
	402	ret = PTR_ERR(sch);
	403	else
	404	ret = 0;
	405	switch (ret) {
	406	case 0:
	407	break;
	408	case -ENOMEM:
	409	panic("Out of memory in init_channel_subsystem\n");
	410	/* -ENXIO: no more subchannels. */
	411	case -ENXIO:
	412	return ret;
	413	default:
	414	return 0;
	415	}
	416	}
	417	/*
	418	* We register ALL valid subchannels in ioinfo, even those
	419	* that have been present before init_channel_subsystem.
	420	* These subchannels can't have been registered yet (kmalloc
	421	* not working) so we do it now. This is true e.g. for the
	422	* console subchannel.
	423	*/
	424	css_register_subchannel(sch);
	425	return 0;
	426	}
	427
1da177e4	428	static void __init
a28c6944	429	css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
1da177e4	430	{
a28c6944 CH	431	if (css_characteristics_avail && css_general_characteristics.mcss) {
	432	css->global_pgid.pgid_high.ext_cssid.version = 0x80;
	433	css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
	434	} else {
1da177e4	435	#ifdef CONFIG_SMP
a28c6944	436	css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
1da177e4	437	#else
a28c6944	438	css->global_pgid.pgid_high.cpu_addr = 0;
1da177e4 LT	439	#endif
1da177e4 LT	440	}
a28c6944 CH	441	css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
	442	css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
	443	css->global_pgid.tod_high = tod_high;
	444
	445	}
	446
3b793060 CH	447	static void
	448	channel_subsystem_release(struct device *dev)
	449	{
	450	struct channel_subsystem *css;
	451
	452	css = to_css(dev);
	453	kfree(css);
	454	}
	455
a28c6944 CH	456	static inline void __init
	457	setup_css(int nr)
	458	{
	459	u32 tod_high;
	460
	461	memset(css[nr], 0, sizeof(struct channel_subsystem));
	462	css[nr]->valid = 1;
	463	css[nr]->cssid = nr;
	464	sprintf(css[nr]->device.bus_id, "css%x", nr);
3b793060	465	css[nr]->device.release = channel_subsystem_release;
a28c6944 CH	466	tod_high = (u32) (get_clock() >> 32);
a28c6944 CH	467	css_generate_pgid(css[nr], tod_high);
1da177e4 LT	468	}
	469
	470	/*
	471	* Now that the driver core is running, we can setup our channel subsystem.
	472	* The struct subchannel's are created during probing (except for the
	473	* static console subchannel).
	474	*/
	475	static int __init
	476	init_channel_subsystem (void)
	477	{
a28c6944	478	int ret, i;
1da177e4 LT	479
	480	if (chsc_determine_css_characteristics() == 0)
	481	css_characteristics_avail = 1;
	482
1da177e4 LT	483	if ((ret = bus_register(&css_bus_type)))
1da177e4 LT	484	goto out;
1da177e4	485
fb6958a5 CH	486	/* Try to enable MSS. */
	487	ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
	488	switch (ret) {
	489	case 0: /* Success. */
	490	max_ssid = __MAX_SSID;
	491	break;
	492	case -ENOMEM:
	493	goto out_bus;
	494	default:
	495	max_ssid = 0;
	496	}
a28c6944 CH	497	/* Setup css structure. */
	498	for (i = 0; i <= __MAX_CSSID; i++) {
	499	css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
	500	if (!css[i]) {
	501	ret = -ENOMEM;
fb6958a5	502	goto out_unregister;
a28c6944 CH	503	}
	504	setup_css(i);
	505	ret = device_register(&css[i]->device);
	506	if (ret)
	507	goto out_free;
	508	}
1da177e4 LT	509	css_init_done = 1;
	510
	511	ctl_set_bit(6, 28);
	512
f97a56fb	513	for_each_subchannel(__init_channel_subsystem, NULL);
1da177e4	514	return 0;
a28c6944 CH	515	out_free:
a28c6944 CH	516	kfree(css[i]);
fb6958a5	517	out_unregister:
a28c6944 CH	518	while (i > 0) {
	519	i--;
	520	device_unregister(&css[i]->device);
	521	}
fb6958a5	522	out_bus:
1da177e4 LT	523	bus_unregister(&css_bus_type);
	524	out:
	525	return ret;
	526	}
	527
	528	/*
	529	* find a driver for a subchannel. They identify by the subchannel
	530	* type with the exception that the console subchannel driver has its own
	531	* subchannel type although the device is an i/o subchannel
	532	*/
	533	static int
	534	css_bus_match (struct device dev, struct device_driver drv)
	535	{
	536	struct subchannel *sch = container_of (dev, struct subchannel, dev);
	537	struct css_driver *driver = container_of (drv, struct css_driver, drv);
	538
	539	if (sch->st == driver->subchannel_type)
	540	return 1;
	541
	542	return 0;
	543	}
	544
	545	struct bus_type css_bus_type = {
	546	.name = "css",
	547	.match = &css_bus_match,
	548	};
	549
	550	subsys_initcall(init_channel_subsystem);
	551
1da177e4	552	int
a8237fc4	553	css_enqueue_subchannel_slow(struct subchannel_id schid)
1da177e4 LT	554	{
	555	struct slow_subchannel *new_slow_sch;
	556	unsigned long flags;
	557
	558	new_slow_sch = kmalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
	559	if (!new_slow_sch)
	560	return -ENOMEM;
	561	memset(new_slow_sch, 0, sizeof(struct slow_subchannel));
	562	new_slow_sch->schid = schid;
	563	spin_lock_irqsave(&slow_subchannel_lock, flags);
	564	list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
	565	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
	566	return 0;
	567	}
	568
	569	void
	570	css_clear_subchannel_slow_list(void)
	571	{
	572	unsigned long flags;
	573
	574	spin_lock_irqsave(&slow_subchannel_lock, flags);
	575	while (!list_empty(&slow_subchannels_head)) {
	576	struct slow_subchannel *slow_sch =
	577	list_entry(slow_subchannels_head.next,
	578	struct slow_subchannel, slow_list);
	579
	580	list_del_init(slow_subchannels_head.next);
	581	kfree(slow_sch);
	582	}
	583	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
	584	}
	585
	586
	587
	588	int
	589	css_slow_subchannels_exist(void)
	590	{
	591	return (!list_empty(&slow_subchannels_head));
	592	}
	593
	594	MODULE_LICENSE("GPL");
	595	EXPORT_SYMBOL(css_bus_type);
1da177e4	596	EXPORT_SYMBOL_GPL(css_characteristics_avail);