Initial import

1 files changed, 1272 insertions, 0 deletions

diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
new file mode 100644
index 000000000..41ba56d2e
--- /dev/null
+++ b/drivers/s390/char/sclp.c
@@ -0,0 +1,1272 @@
+/*
+ * core function to access sclp interface
+ *
+ * Copyright IBM Corp. 1999, 2009
+ *
+ * Author(s): Martin Peschke <mpeschke@de.ibm.com>
+ *	      Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/timer.h>
+#include <linux/reboot.h>
+#include <linux/jiffies.h>
+#include <linux/init.h>
+#include <linux/suspend.h>
+#include <linux/completion.h>
+#include <linux/platform_device.h>
+#include <asm/types.h>
+#include <asm/irq.h>
+
+#include "sclp.h"
+
+#define SCLP_HEADER		"sclp: "
+
+/* Lock to protect internal data consistency. */
+static DEFINE_SPINLOCK(sclp_lock);
+
+/* Mask of events that we can send to the sclp interface. */
+static sccb_mask_t sclp_receive_mask;
+
+/* Mask of events that we can receive from the sclp interface. */
+static sccb_mask_t sclp_send_mask;
+
+/* List of registered event listeners and senders. */
+static struct list_head sclp_reg_list;
+
+/* List of queued requests. */
+static struct list_head sclp_req_queue;
+
+/* Data for read and and init requests. */
+static struct sclp_req sclp_read_req;
+static struct sclp_req sclp_init_req;
+static char sclp_read_sccb[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
+static char sclp_init_sccb[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
+
+/* Suspend request */
+static DECLARE_COMPLETION(sclp_request_queue_flushed);
+
+/* Number of console pages to allocate, used by sclp_con.c and sclp_vt220.c */
+int sclp_console_pages = SCLP_CONSOLE_PAGES;
+/* Flag to indicate if buffer pages are dropped on buffer full condition */
+int sclp_console_drop = 0;
+/* Number of times the console dropped buffer pages */
+unsigned long sclp_console_full;
+
+static void sclp_suspend_req_cb(struct sclp_req *req, void *data)
+{
+	complete(&sclp_request_queue_flushed);
+}
+
+static int __init sclp_setup_console_pages(char *str)
+{
+	int pages, rc;
+
+	rc = kstrtoint(str, 0, &pages);
+	if (!rc && pages >= SCLP_CONSOLE_PAGES)
+		sclp_console_pages = pages;
+	return 1;
+}
+
+__setup("sclp_con_pages=", sclp_setup_console_pages);
+
+static int __init sclp_setup_console_drop(char *str)
+{
+	int drop, rc;
+
+	rc = kstrtoint(str, 0, &drop);
+	if (!rc && drop)
+		sclp_console_drop = 1;
+	return 1;
+}
+
+__setup("sclp_con_drop=", sclp_setup_console_drop);
+
+static struct sclp_req sclp_suspend_req;
+
+/* Timer for request retries. */
+static struct timer_list sclp_request_timer;
+
+/* Timer for queued requests. */
+static struct timer_list sclp_queue_timer;
+
+/* Internal state: is the driver initialized? */
+static volatile enum sclp_init_state_t {
+	sclp_init_state_uninitialized,
+	sclp_init_state_initializing,
+	sclp_init_state_initialized
+} sclp_init_state = sclp_init_state_uninitialized;
+
+/* Internal state: is a request active at the sclp? */
+static volatile enum sclp_running_state_t {
+	sclp_running_state_idle,
+	sclp_running_state_running,
+	sclp_running_state_reset_pending
+} sclp_running_state = sclp_running_state_idle;
+
+/* Internal state: is a read request pending? */
+static volatile enum sclp_reading_state_t {
+	sclp_reading_state_idle,
+	sclp_reading_state_reading
+} sclp_reading_state = sclp_reading_state_idle;
+
+/* Internal state: is the driver currently serving requests? */
+static volatile enum sclp_activation_state_t {
+	sclp_activation_state_active,
+	sclp_activation_state_deactivating,
+	sclp_activation_state_inactive,
+	sclp_activation_state_activating
+} sclp_activation_state = sclp_activation_state_active;
+
+/* Internal state: is an init mask request pending? */
+static volatile enum sclp_mask_state_t {
+	sclp_mask_state_idle,
+	sclp_mask_state_initializing
+} sclp_mask_state = sclp_mask_state_idle;
+
+/* Internal state: is the driver suspended? */
+static enum sclp_suspend_state_t {
+	sclp_suspend_state_running,
+	sclp_suspend_state_suspended,
+} sclp_suspend_state = sclp_suspend_state_running;
+
+/* Maximum retry counts */
+#define SCLP_INIT_RETRY		3
+#define SCLP_MASK_RETRY		3
+
+/* Timeout intervals in seconds.*/
+#define SCLP_BUSY_INTERVAL	10
+#define SCLP_RETRY_INTERVAL	30
+
+static void sclp_process_queue(void);
+static void __sclp_make_read_req(void);
+static int sclp_init_mask(int calculate);
+static int sclp_init(void);
+
+/* Perform service call. Return 0 on success, non-zero otherwise. */
+int
+sclp_service_call(sclp_cmdw_t command, void *sccb)
+{
+	int cc = 4; /* Initialize for program check handling */
+
+	asm volatile(
+		"0:	.insn	rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
+		"1:	ipm	%0\n"
+		"	srl	%0,28\n"
+		"2:\n"
+		EX_TABLE(0b, 2b)
+		EX_TABLE(1b, 2b)
+		: "+&d" (cc) : "d" (command), "a" (__pa(sccb))
+		: "cc", "memory");
+	if (cc == 4)
+		return -EINVAL;
+	if (cc == 3)
+		return -EIO;
+	if (cc == 2)
+		return -EBUSY;
+	return 0;
+}
+
+
+static void
+__sclp_queue_read_req(void)
+{
+	if (sclp_reading_state == sclp_reading_state_idle) {
+		sclp_reading_state = sclp_reading_state_reading;
+		__sclp_make_read_req();
+		/* Add request to head of queue */
+		list_add(&sclp_read_req.list, &sclp_req_queue);
+	}
+}
+
+/* Set up request retry timer. Called while sclp_lock is locked. */
+static inline void
+__sclp_set_request_timer(unsigned long time, void (*function)(unsigned long),
+			 unsigned long data)
+{
+	del_timer(&sclp_request_timer);
+	sclp_request_timer.function = function;
+	sclp_request_timer.data = data;
+	sclp_request_timer.expires = jiffies + time;
+	add_timer(&sclp_request_timer);
+}
+
+/* Request timeout handler. Restart the request queue. If DATA is non-zero,
+ * force restart of running request. */
+static void
+sclp_request_timeout(unsigned long data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (data) {
+		if (sclp_running_state == sclp_running_state_running) {
+			/* Break running state and queue NOP read event request
+			 * to get a defined interface state. */
+			__sclp_queue_read_req();
+			sclp_running_state = sclp_running_state_idle;
+		}
+	} else {
+		__sclp_set_request_timer(SCLP_BUSY_INTERVAL * HZ,
+					 sclp_request_timeout, 0);
+	}
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	sclp_process_queue();
+}
+
+/*
+ * Returns the expire value in jiffies of the next pending request timeout,
+ * if any. Needs to be called with sclp_lock.
+ */
+static unsigned long __sclp_req_queue_find_next_timeout(void)
+{
+	unsigned long expires_next = 0;
+	struct sclp_req *req;
+
+	list_for_each_entry(req, &sclp_req_queue, list) {
+		if (!req->queue_expires)
+			continue;
+		if (!expires_next ||
+		   (time_before(req->queue_expires, expires_next)))
+				expires_next = req->queue_expires;
+	}
+	return expires_next;
+}
+
+/*
+ * Returns expired request, if any, and removes it from the list.
+ */
+static struct sclp_req *__sclp_req_queue_remove_expired_req(void)
+{
+	unsigned long flags, now;
+	struct sclp_req *req;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	now = jiffies;
+	/* Don't need list_for_each_safe because we break out after list_del */
+	list_for_each_entry(req, &sclp_req_queue, list) {
+		if (!req->queue_expires)
+			continue;
+		if (time_before_eq(req->queue_expires, now)) {
+			if (req->status == SCLP_REQ_QUEUED) {
+				req->status = SCLP_REQ_QUEUED_TIMEOUT;
+				list_del(&req->list);
+				goto out;
+			}
+		}
+	}
+	req = NULL;
+out:
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return req;
+}
+
+/*
+ * Timeout handler for queued requests. Removes request from list and
+ * invokes callback. This timer can be set per request in situations where
+ * waiting too long would be harmful to the system, e.g. during SE reboot.
+ */
+static void sclp_req_queue_timeout(unsigned long data)
+{
+	unsigned long flags, expires_next;
+	struct sclp_req *req;
+
+	do {
+		req = __sclp_req_queue_remove_expired_req();
+		if (req && req->callback)
+			req->callback(req, req->callback_data);
+	} while (req);
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	expires_next = __sclp_req_queue_find_next_timeout();
+	if (expires_next)
+		mod_timer(&sclp_queue_timer, expires_next);
+	spin_unlock_irqrestore(&sclp_lock, flags);
+}
+
+/* Try to start a request. Return zero if the request was successfully
+ * started or if it will be started at a later time. Return non-zero otherwise.
+ * Called while sclp_lock is locked. */
+static int
+__sclp_start_request(struct sclp_req *req)
+{
+	int rc;
+
+	if (sclp_running_state != sclp_running_state_idle)
+		return 0;
+	del_timer(&sclp_request_timer);
+	rc = sclp_service_call(req->command, req->sccb);
+	req->start_count++;
+
+	if (rc == 0) {
+		/* Successfully started request */
+		req->status = SCLP_REQ_RUNNING;
+		sclp_running_state = sclp_running_state_running;
+		__sclp_set_request_timer(SCLP_RETRY_INTERVAL * HZ,
+					 sclp_request_timeout, 1);
+		return 0;
+	} else if (rc == -EBUSY) {
+		/* Try again later */
+		__sclp_set_request_timer(SCLP_BUSY_INTERVAL * HZ,
+					 sclp_request_timeout, 0);
+		return 0;
+	}
+	/* Request failed */
+	req->status = SCLP_REQ_FAILED;
+	return rc;
+}
+
+/* Try to start queued requests. */
+static void
+sclp_process_queue(void)
+{
+	struct sclp_req *req;
+	int rc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (sclp_running_state != sclp_running_state_idle) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return;
+	}
+	del_timer(&sclp_request_timer);
+	while (!list_empty(&sclp_req_queue)) {
+		req = list_entry(sclp_req_queue.next, struct sclp_req, list);
+		if (!req->sccb)
+			goto do_post;
+		rc = __sclp_start_request(req);
+		if (rc == 0)
+			break;
+		/* Request failed */
+		if (req->start_count > 1) {
+			/* Cannot abort already submitted request - could still
+			 * be active at the SCLP */
+			__sclp_set_request_timer(SCLP_BUSY_INTERVAL * HZ,
+						 sclp_request_timeout, 0);
+			break;
+		}
+do_post:
+		/* Post-processing for aborted request */
+		list_del(&req->list);
+		if (req->callback) {
+			spin_unlock_irqrestore(&sclp_lock, flags);
+			req->callback(req, req->callback_data);
+			spin_lock_irqsave(&sclp_lock, flags);
+		}
+	}
+	spin_unlock_irqrestore(&sclp_lock, flags);
+}
+
+static int __sclp_can_add_request(struct sclp_req *req)
+{
+	if (req == &sclp_suspend_req || req == &sclp_init_req)
+		return 1;
+	if (sclp_suspend_state != sclp_suspend_state_running)
+		return 0;
+	if (sclp_init_state != sclp_init_state_initialized)
+		return 0;
+	if (sclp_activation_state != sclp_activation_state_active)
+		return 0;
+	return 1;
+}
+
+/* Queue a new request. Return zero on success, non-zero otherwise. */
+int
+sclp_add_request(struct sclp_req *req)
+{
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (!__sclp_can_add_request(req)) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return -EIO;
+	}
+	req->status = SCLP_REQ_QUEUED;
+	req->start_count = 0;
+	list_add_tail(&req->list, &sclp_req_queue);
+	rc = 0;
+	if (req->queue_timeout) {
+		req->queue_expires = jiffies + req->queue_timeout * HZ;
+		if (!timer_pending(&sclp_queue_timer) ||
+		    time_after(sclp_queue_timer.expires, req->queue_expires))
+			mod_timer(&sclp_queue_timer, req->queue_expires);
+	} else
+		req->queue_expires = 0;
+	/* Start if request is first in list */
+	if (sclp_running_state == sclp_running_state_idle &&
+	    req->list.prev == &sclp_req_queue) {
+		if (!req->sccb) {
+			list_del(&req->list);
+			rc = -ENODATA;
+			goto out;
+		}
+		rc = __sclp_start_request(req);
+		if (rc)
+			list_del(&req->list);
+	}
+out:
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+EXPORT_SYMBOL(sclp_add_request);
+
+/* Dispatch events found in request buffer to registered listeners. Return 0
+ * if all events were dispatched, non-zero otherwise. */
+static int
+sclp_dispatch_evbufs(struct sccb_header *sccb)
+{
+	unsigned long flags;
+	struct evbuf_header *evbuf;
+	struct list_head *l;
+	struct sclp_register *reg;
+	int offset;
+	int rc;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	rc = 0;
+	for (offset = sizeof(struct sccb_header); offset < sccb->length;
+	     offset += evbuf->length) {
+		evbuf = (struct evbuf_header *) ((addr_t) sccb + offset);
+		/* Check for malformed hardware response */
+		if (evbuf->length == 0)
+			break;
+		/* Search for event handler */
+		reg = NULL;
+		list_for_each(l, &sclp_reg_list) {
+			reg = list_entry(l, struct sclp_register, list);
+			if (reg->receive_mask & (1 << (32 - evbuf->type)))
+				break;
+			else
+				reg = NULL;
+		}
+		if (reg && reg->receiver_fn) {
+			spin_unlock_irqrestore(&sclp_lock, flags);
+			reg->receiver_fn(evbuf);
+			spin_lock_irqsave(&sclp_lock, flags);
+		} else if (reg == NULL)
+			rc = -EOPNOTSUPP;
+	}
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+/* Read event data request callback. */
+static void
+sclp_read_cb(struct sclp_req *req, void *data)
+{
+	unsigned long flags;
+	struct sccb_header *sccb;
+
+	sccb = (struct sccb_header *) req->sccb;
+	if (req->status == SCLP_REQ_DONE && (sccb->response_code == 0x20 ||
+	    sccb->response_code == 0x220))
+		sclp_dispatch_evbufs(sccb);
+	spin_lock_irqsave(&sclp_lock, flags);
+	sclp_reading_state = sclp_reading_state_idle;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+}
+
+/* Prepare read event data request. Called while sclp_lock is locked. */
+static void __sclp_make_read_req(void)
+{
+	struct sccb_header *sccb;
+
+	sccb = (struct sccb_header *) sclp_read_sccb;
+	clear_page(sccb);
+	memset(&sclp_read_req, 0, sizeof(struct sclp_req));
+	sclp_read_req.command = SCLP_CMDW_READ_EVENT_DATA;
+	sclp_read_req.status = SCLP_REQ_QUEUED;
+	sclp_read_req.start_count = 0;
+	sclp_read_req.callback = sclp_read_cb;
+	sclp_read_req.sccb = sccb;
+	sccb->length = PAGE_SIZE;
+	sccb->function_code = 0;
+	sccb->control_mask[2] = 0x80;
+}
+
+/* Search request list for request with matching sccb. Return request if found,
+ * NULL otherwise. Called while sclp_lock is locked. */
+static inline struct sclp_req *
+__sclp_find_req(u32 sccb)
+{
+	struct list_head *l;
+	struct sclp_req *req;
+
+	list_for_each(l, &sclp_req_queue) {
+		req = list_entry(l, struct sclp_req, list);
+		if (sccb == (u32) (addr_t) req->sccb)
+				return req;
+	}
+	return NULL;
+}
+
+/* Handler for external interruption. Perform request post-processing.
+ * Prepare read event data request if necessary. Start processing of next
+ * request on queue. */
+static void sclp_interrupt_handler(struct ext_code ext_code,
+				   unsigned int param32, unsigned long param64)
+{
+	struct sclp_req *req;
+	u32 finished_sccb;
+	u32 evbuf_pending;
+
+	inc_irq_stat(IRQEXT_SCP);
+	spin_lock(&sclp_lock);
+	finished_sccb = param32 & 0xfffffff8;
+	evbuf_pending = param32 & 0x3;
+	if (finished_sccb) {
+		del_timer(&sclp_request_timer);
+		sclp_running_state = sclp_running_state_reset_pending;
+		req = __sclp_find_req(finished_sccb);
+		if (req) {
+			/* Request post-processing */
+			list_del(&req->list);
+			req->status = SCLP_REQ_DONE;
+			if (req->callback) {
+				spin_unlock(&sclp_lock);
+				req->callback(req, req->callback_data);
+				spin_lock(&sclp_lock);
+			}
+		}
+		sclp_running_state = sclp_running_state_idle;
+	}
+	if (evbuf_pending &&
+	    sclp_activation_state == sclp_activation_state_active)
+		__sclp_queue_read_req();
+	spin_unlock(&sclp_lock);
+	sclp_process_queue();
+}
+
+/* Convert interval in jiffies to TOD ticks. */
+static inline u64
+sclp_tod_from_jiffies(unsigned long jiffies)
+{
+	return (u64) (jiffies / HZ) << 32;
+}
+
+/* Wait until a currently running request finished. Note: while this function
+ * is running, no timers are served on the calling CPU. */
+void
+sclp_sync_wait(void)
+{
+	unsigned long long old_tick;
+	unsigned long flags;
+	unsigned long cr0, cr0_sync;
+	u64 timeout;
+	int irq_context;
+
+	/* We'll be disabling timer interrupts, so we need a custom timeout
+	 * mechanism */
+	timeout = 0;
+	if (timer_pending(&sclp_request_timer)) {
+		/* Get timeout TOD value */
+		timeout = get_tod_clock_fast() +
+			  sclp_tod_from_jiffies(sclp_request_timer.expires -
+						jiffies);
+	}
+	local_irq_save(flags);
+	/* Prevent bottom half from executing once we force interrupts open */
+	irq_context = in_interrupt();
+	if (!irq_context)
+		local_bh_disable();
+	/* Enable service-signal interruption, disable timer interrupts */
+	old_tick = local_tick_disable();
+	trace_hardirqs_on();
+	__ctl_store(cr0, 0, 0);
+	cr0_sync = cr0;
+	cr0_sync &= 0xffff00a0;
+	cr0_sync |= 0x00000200;
+	__ctl_load(cr0_sync, 0, 0);
+	__arch_local_irq_stosm(0x01);
+	/* Loop until driver state indicates finished request */
+	while (sclp_running_state != sclp_running_state_idle) {
+		/* Check for expired request timer */
+		if (timer_pending(&sclp_request_timer) &&
+		    get_tod_clock_fast() > timeout &&
+		    del_timer(&sclp_request_timer))
+			sclp_request_timer.function(sclp_request_timer.data);
+		cpu_relax();
+	}
+	local_irq_disable();
+	__ctl_load(cr0, 0, 0);
+	if (!irq_context)
+		_local_bh_enable();
+	local_tick_enable(old_tick);
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL(sclp_sync_wait);
+
+/* Dispatch changes in send and receive mask to registered listeners. */
+static void
+sclp_dispatch_state_change(void)
+{
+	struct list_head *l;
+	struct sclp_register *reg;
+	unsigned long flags;
+	sccb_mask_t receive_mask;
+	sccb_mask_t send_mask;
+
+	do {
+		spin_lock_irqsave(&sclp_lock, flags);
+		reg = NULL;
+		list_for_each(l, &sclp_reg_list) {
+			reg = list_entry(l, struct sclp_register, list);
+			receive_mask = reg->send_mask & sclp_receive_mask;
+			send_mask = reg->receive_mask & sclp_send_mask;
+			if (reg->sclp_receive_mask != receive_mask ||
+			    reg->sclp_send_mask != send_mask) {
+				reg->sclp_receive_mask = receive_mask;
+				reg->sclp_send_mask = send_mask;
+				break;
+			} else
+				reg = NULL;
+		}
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		if (reg && reg->state_change_fn)
+			reg->state_change_fn(reg);
+	} while (reg);
+}
+
+struct sclp_statechangebuf {
+	struct evbuf_header	header;
+	u8		validity_sclp_active_facility_mask : 1;
+	u8		validity_sclp_receive_mask : 1;
+	u8		validity_sclp_send_mask : 1;
+	u8		validity_read_data_function_mask : 1;
+	u16		_zeros : 12;
+	u16		mask_length;
+	u64		sclp_active_facility_mask;
+	sccb_mask_t	sclp_receive_mask;
+	sccb_mask_t	sclp_send_mask;
+	u32		read_data_function_mask;
+} __attribute__((packed));
+
+
+/* State change event callback. Inform listeners of changes. */
+static void
+sclp_state_change_cb(struct evbuf_header *evbuf)
+{
+	unsigned long flags;
+	struct sclp_statechangebuf *scbuf;
+
+	scbuf = (struct sclp_statechangebuf *) evbuf;
+	if (scbuf->mask_length != sizeof(sccb_mask_t))
+		return;
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (scbuf->validity_sclp_receive_mask)
+		sclp_receive_mask = scbuf->sclp_receive_mask;
+	if (scbuf->validity_sclp_send_mask)
+		sclp_send_mask = scbuf->sclp_send_mask;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	if (scbuf->validity_sclp_active_facility_mask)
+		sclp_facilities = scbuf->sclp_active_facility_mask;
+	sclp_dispatch_state_change();
+}
+
+static struct sclp_register sclp_state_change_event = {
+	.receive_mask = EVTYP_STATECHANGE_MASK,
+	.receiver_fn = sclp_state_change_cb
+};
+
+/* Calculate receive and send mask of currently registered listeners.
+ * Called while sclp_lock is locked. */
+static inline void
+__sclp_get_mask(sccb_mask_t *receive_mask, sccb_mask_t *send_mask)
+{
+	struct list_head *l;
+	struct sclp_register *t;
+
+	*receive_mask = 0;
+	*send_mask = 0;
+	list_for_each(l, &sclp_reg_list) {
+		t = list_entry(l, struct sclp_register, list);
+		*receive_mask |= t->receive_mask;
+		*send_mask |= t->send_mask;
+	}
+}
+
+/* Register event listener. Return 0 on success, non-zero otherwise. */
+int
+sclp_register(struct sclp_register *reg)
+{
+	unsigned long flags;
+	sccb_mask_t receive_mask;
+	sccb_mask_t send_mask;
+	int rc;
+
+	rc = sclp_init();
+	if (rc)
+		return rc;
+	spin_lock_irqsave(&sclp_lock, flags);
+	/* Check event mask for collisions */
+	__sclp_get_mask(&receive_mask, &send_mask);
+	if (reg->receive_mask & receive_mask || reg->send_mask & send_mask) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return -EBUSY;
+	}
+	/* Trigger initial state change callback */
+	reg->sclp_receive_mask = 0;
+	reg->sclp_send_mask = 0;
+	reg->pm_event_posted = 0;
+	list_add(&reg->list, &sclp_reg_list);
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	rc = sclp_init_mask(1);
+	if (rc) {
+		spin_lock_irqsave(&sclp_lock, flags);
+		list_del(&reg->list);
+		spin_unlock_irqrestore(&sclp_lock, flags);
+	}
+	return rc;
+}
+
+EXPORT_SYMBOL(sclp_register);
+
+/* Unregister event listener. */
+void
+sclp_unregister(struct sclp_register *reg)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	list_del(&reg->list);
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	sclp_init_mask(1);
+}
+
+EXPORT_SYMBOL(sclp_unregister);
+
+/* Remove event buffers which are marked processed. Return the number of
+ * remaining event buffers. */
+int
+sclp_remove_processed(struct sccb_header *sccb)
+{
+	struct evbuf_header *evbuf;
+	int unprocessed;
+	u16 remaining;
+
+	evbuf = (struct evbuf_header *) (sccb + 1);
+	unprocessed = 0;
+	remaining = sccb->length - sizeof(struct sccb_header);
+	while (remaining > 0) {
+		remaining -= evbuf->length;
+		if (evbuf->flags & 0x80) {
+			sccb->length -= evbuf->length;
+			memcpy(evbuf, (void *) ((addr_t) evbuf + evbuf->length),
+			       remaining);
+		} else {
+			unprocessed++;
+			evbuf = (struct evbuf_header *)
+					((addr_t) evbuf + evbuf->length);
+		}
+	}
+	return unprocessed;
+}
+
+EXPORT_SYMBOL(sclp_remove_processed);
+
+/* Prepare init mask request. Called while sclp_lock is locked. */
+static inline void
+__sclp_make_init_req(u32 receive_mask, u32 send_mask)
+{
+	struct init_sccb *sccb;
+
+	sccb = (struct init_sccb *) sclp_init_sccb;
+	clear_page(sccb);
+	memset(&sclp_init_req, 0, sizeof(struct sclp_req));
+	sclp_init_req.command = SCLP_CMDW_WRITE_EVENT_MASK;
+	sclp_init_req.status = SCLP_REQ_FILLED;
+	sclp_init_req.start_count = 0;
+	sclp_init_req.callback = NULL;
+	sclp_init_req.callback_data = NULL;
+	sclp_init_req.sccb = sccb;
+	sccb->header.length = sizeof(struct init_sccb);
+	sccb->mask_length = sizeof(sccb_mask_t);
+	sccb->receive_mask = receive_mask;
+	sccb->send_mask = send_mask;
+	sccb->sclp_receive_mask = 0;
+	sccb->sclp_send_mask = 0;
+}
+
+/* Start init mask request. If calculate is non-zero, calculate the mask as
+ * requested by registered listeners. Use zero mask otherwise. Return 0 on
+ * success, non-zero otherwise. */
+static int
+sclp_init_mask(int calculate)
+{
+	unsigned long flags;
+	struct init_sccb *sccb = (struct init_sccb *) sclp_init_sccb;
+	sccb_mask_t receive_mask;
+	sccb_mask_t send_mask;
+	int retry;
+	int rc;
+	unsigned long wait;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	/* Check if interface is in appropriate state */
+	if (sclp_mask_state != sclp_mask_state_idle) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return -EBUSY;
+	}
+	if (sclp_activation_state == sclp_activation_state_inactive) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return -EINVAL;
+	}
+	sclp_mask_state = sclp_mask_state_initializing;
+	/* Determine mask */
+	if (calculate)
+		__sclp_get_mask(&receive_mask, &send_mask);
+	else {
+		receive_mask = 0;
+		send_mask = 0;
+	}
+	rc = -EIO;
+	for (retry = 0; retry <= SCLP_MASK_RETRY; retry++) {
+		/* Prepare request */
+		__sclp_make_init_req(receive_mask, send_mask);
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		if (sclp_add_request(&sclp_init_req)) {
+			/* Try again later */
+			wait = jiffies + SCLP_BUSY_INTERVAL * HZ;
+			while (time_before(jiffies, wait))
+				sclp_sync_wait();
+			spin_lock_irqsave(&sclp_lock, flags);
+			continue;
+		}
+		while (sclp_init_req.status != SCLP_REQ_DONE &&
+		       sclp_init_req.status != SCLP_REQ_FAILED)
+			sclp_sync_wait();
+		spin_lock_irqsave(&sclp_lock, flags);
+		if (sclp_init_req.status == SCLP_REQ_DONE &&
+		    sccb->header.response_code == 0x20) {
+			/* Successful request */
+			if (calculate) {
+				sclp_receive_mask = sccb->sclp_receive_mask;
+				sclp_send_mask = sccb->sclp_send_mask;
+			} else {
+				sclp_receive_mask = 0;
+				sclp_send_mask = 0;
+			}
+			spin_unlock_irqrestore(&sclp_lock, flags);
+			sclp_dispatch_state_change();
+			spin_lock_irqsave(&sclp_lock, flags);
+			rc = 0;
+			break;
+		}
+	}
+	sclp_mask_state = sclp_mask_state_idle;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+/* Deactivate SCLP interface. On success, new requests will be rejected,
+ * events will no longer be dispatched. Return 0 on success, non-zero
+ * otherwise. */
+int
+sclp_deactivate(void)
+{
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	/* Deactivate can only be called when active */
+	if (sclp_activation_state != sclp_activation_state_active) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return -EINVAL;
+	}
+	sclp_activation_state = sclp_activation_state_deactivating;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	rc = sclp_init_mask(0);
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (rc == 0)
+		sclp_activation_state = sclp_activation_state_inactive;
+	else
+		sclp_activation_state = sclp_activation_state_active;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+EXPORT_SYMBOL(sclp_deactivate);
+
+/* Reactivate SCLP interface after sclp_deactivate. On success, new
+ * requests will be accepted, events will be dispatched again. Return 0 on
+ * success, non-zero otherwise. */
+int
+sclp_reactivate(void)
+{
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	/* Reactivate can only be called when inactive */
+	if (sclp_activation_state != sclp_activation_state_inactive) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return -EINVAL;
+	}
+	sclp_activation_state = sclp_activation_state_activating;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	rc = sclp_init_mask(1);
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (rc == 0)
+		sclp_activation_state = sclp_activation_state_active;
+	else
+		sclp_activation_state = sclp_activation_state_inactive;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+EXPORT_SYMBOL(sclp_reactivate);
+
+/* Handler for external interruption used during initialization. Modify
+ * request state to done. */
+static void sclp_check_handler(struct ext_code ext_code,
+			       unsigned int param32, unsigned long param64)
+{
+	u32 finished_sccb;
+
+	inc_irq_stat(IRQEXT_SCP);
+	finished_sccb = param32 & 0xfffffff8;
+	/* Is this the interrupt we are waiting for? */
+	if (finished_sccb == 0)
+		return;
+	if (finished_sccb != (u32) (addr_t) sclp_init_sccb)
+		panic("sclp: unsolicited interrupt for buffer at 0x%x\n",
+		      finished_sccb);
+	spin_lock(&sclp_lock);
+	if (sclp_running_state == sclp_running_state_running) {
+		sclp_init_req.status = SCLP_REQ_DONE;
+		sclp_running_state = sclp_running_state_idle;
+	}
+	spin_unlock(&sclp_lock);
+}
+
+/* Initial init mask request timed out. Modify request state to failed. */
+static void
+sclp_check_timeout(unsigned long data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (sclp_running_state == sclp_running_state_running) {
+		sclp_init_req.status = SCLP_REQ_FAILED;
+		sclp_running_state = sclp_running_state_idle;
+	}
+	spin_unlock_irqrestore(&sclp_lock, flags);
+}
+
+/* Perform a check of the SCLP interface. Return zero if the interface is
+ * available and there are no pending requests from a previous instance.
+ * Return non-zero otherwise. */
+static int
+sclp_check_interface(void)
+{
+	struct init_sccb *sccb;
+	unsigned long flags;
+	int retry;
+	int rc;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	/* Prepare init mask command */
+	rc = register_external_irq(EXT_IRQ_SERVICE_SIG, sclp_check_handler);
+	if (rc) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return rc;
+	}
+	for (retry = 0; retry <= SCLP_INIT_RETRY; retry++) {
+		__sclp_make_init_req(0, 0);
+		sccb = (struct init_sccb *) sclp_init_req.sccb;
+		rc = sclp_service_call(sclp_init_req.command, sccb);
+		if (rc == -EIO)
+			break;
+		sclp_init_req.status = SCLP_REQ_RUNNING;
+		sclp_running_state = sclp_running_state_running;
+		__sclp_set_request_timer(SCLP_RETRY_INTERVAL * HZ,
+					 sclp_check_timeout, 0);
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		/* Enable service-signal interruption - needs to happen
+		 * with IRQs enabled. */
+		irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
+		/* Wait for signal from interrupt or timeout */
+		sclp_sync_wait();
+		/* Disable service-signal interruption - needs to happen
+		 * with IRQs enabled. */
+		irq_subclass_unregister(IRQ_SUBCLASS_SERVICE_SIGNAL);
+		spin_lock_irqsave(&sclp_lock, flags);
+		del_timer(&sclp_request_timer);
+		if (sclp_init_req.status == SCLP_REQ_DONE &&
+		    sccb->header.response_code == 0x20) {
+			rc = 0;
+			break;
+		} else
+			rc = -EBUSY;
+	}
+	unregister_external_irq(EXT_IRQ_SERVICE_SIG, sclp_check_handler);
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+/* Reboot event handler. Reset send and receive mask to prevent pending SCLP
+ * events from interfering with rebooted system. */
+static int
+sclp_reboot_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	sclp_deactivate();
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block sclp_reboot_notifier = {
+	.notifier_call = sclp_reboot_event
+};
+
+/*
+ * Suspend/resume SCLP notifier implementation
+ */
+
+static void sclp_pm_event(enum sclp_pm_event sclp_pm_event, int rollback)
+{
+	struct sclp_register *reg;
+	unsigned long flags;
+
+	if (!rollback) {
+		spin_lock_irqsave(&sclp_lock, flags);
+		list_for_each_entry(reg, &sclp_reg_list, list)
+			reg->pm_event_posted = 0;
+		spin_unlock_irqrestore(&sclp_lock, flags);
+	}
+	do {
+		spin_lock_irqsave(&sclp_lock, flags);
+		list_for_each_entry(reg, &sclp_reg_list, list) {
+			if (rollback && reg->pm_event_posted)
+				goto found;
+			if (!rollback && !reg->pm_event_posted)
+				goto found;
+		}
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return;
+found:
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		if (reg->pm_event_fn)
+			reg->pm_event_fn(reg, sclp_pm_event);
+		reg->pm_event_posted = rollback ? 0 : 1;
+	} while (1);
+}
+
+/*
+ * Susend/resume callbacks for platform device
+ */
+
+static int sclp_freeze(struct device *dev)
+{
+	unsigned long flags;
+	int rc;
+
+	sclp_pm_event(SCLP_PM_EVENT_FREEZE, 0);
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	sclp_suspend_state = sclp_suspend_state_suspended;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+
+	/* Init supend data */
+	memset(&sclp_suspend_req, 0, sizeof(sclp_suspend_req));
+	sclp_suspend_req.callback = sclp_suspend_req_cb;
+	sclp_suspend_req.status = SCLP_REQ_FILLED;
+	init_completion(&sclp_request_queue_flushed);
+
+	rc = sclp_add_request(&sclp_suspend_req);
+	if (rc == 0)
+		wait_for_completion(&sclp_request_queue_flushed);
+	else if (rc != -ENODATA)
+		goto fail_thaw;
+
+	rc = sclp_deactivate();
+	if (rc)
+		goto fail_thaw;
+	return 0;
+
+fail_thaw:
+	spin_lock_irqsave(&sclp_lock, flags);
+	sclp_suspend_state = sclp_suspend_state_running;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	sclp_pm_event(SCLP_PM_EVENT_THAW, 1);
+	return rc;
+}
+
+static int sclp_undo_suspend(enum sclp_pm_event event)
+{
+	unsigned long flags;
+	int rc;
+
+	rc = sclp_reactivate();
+	if (rc)
+		return rc;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	sclp_suspend_state = sclp_suspend_state_running;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+
+	sclp_pm_event(event, 0);
+	return 0;
+}
+
+static int sclp_thaw(struct device *dev)
+{
+	return sclp_undo_suspend(SCLP_PM_EVENT_THAW);
+}
+
+static int sclp_restore(struct device *dev)
+{
+	return sclp_undo_suspend(SCLP_PM_EVENT_RESTORE);
+}
+
+static const struct dev_pm_ops sclp_pm_ops = {
+	.freeze		= sclp_freeze,
+	.thaw		= sclp_thaw,
+	.restore	= sclp_restore,
+};
+
+static ssize_t sclp_show_console_pages(struct device_driver *dev, char *buf)
+{
+	return sprintf(buf, "%i\n", sclp_console_pages);
+}
+
+static DRIVER_ATTR(con_pages, S_IRUSR, sclp_show_console_pages, NULL);
+
+static ssize_t sclp_show_con_drop(struct device_driver *dev, char *buf)
+{
+	return sprintf(buf, "%i\n", sclp_console_drop);
+}
+
+static DRIVER_ATTR(con_drop, S_IRUSR, sclp_show_con_drop, NULL);
+
+static ssize_t sclp_show_console_full(struct device_driver *dev, char *buf)
+{
+	return sprintf(buf, "%lu\n", sclp_console_full);
+}
+
+static DRIVER_ATTR(con_full, S_IRUSR, sclp_show_console_full, NULL);
+
+static struct attribute *sclp_drv_attrs[] = {
+	&driver_attr_con_pages.attr,
+	&driver_attr_con_drop.attr,
+	&driver_attr_con_full.attr,
+	NULL,
+};
+static struct attribute_group sclp_drv_attr_group = {
+	.attrs = sclp_drv_attrs,
+};
+static const struct attribute_group *sclp_drv_attr_groups[] = {
+	&sclp_drv_attr_group,
+	NULL,
+};
+
+static struct platform_driver sclp_pdrv = {
+	.driver = {
+		.name	= "sclp",
+		.pm	= &sclp_pm_ops,
+		.groups = sclp_drv_attr_groups,
+	},
+};
+
+static struct platform_device *sclp_pdev;
+
+/* Initialize SCLP driver. Return zero if driver is operational, non-zero
+ * otherwise. */
+static int
+sclp_init(void)
+{
+	unsigned long flags;
+	int rc = 0;
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	/* Check for previous or running initialization */
+	if (sclp_init_state != sclp_init_state_uninitialized)
+		goto fail_unlock;
+	sclp_init_state = sclp_init_state_initializing;
+	/* Set up variables */
+	INIT_LIST_HEAD(&sclp_req_queue);
+	INIT_LIST_HEAD(&sclp_reg_list);
+	list_add(&sclp_state_change_event.list, &sclp_reg_list);
+	init_timer(&sclp_request_timer);
+	init_timer(&sclp_queue_timer);
+	sclp_queue_timer.function = sclp_req_queue_timeout;
+	/* Check interface */
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	rc = sclp_check_interface();
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (rc)
+		goto fail_init_state_uninitialized;
+	/* Register reboot handler */
+	rc = register_reboot_notifier(&sclp_reboot_notifier);
+	if (rc)
+		goto fail_init_state_uninitialized;
+	/* Register interrupt handler */
+	rc = register_external_irq(EXT_IRQ_SERVICE_SIG, sclp_interrupt_handler);
+	if (rc)
+		goto fail_unregister_reboot_notifier;
+	sclp_init_state = sclp_init_state_initialized;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	/* Enable service-signal external interruption - needs to happen with
+	 * IRQs enabled. */
+	irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
+	sclp_init_mask(1);
+	return 0;
+
+fail_unregister_reboot_notifier:
+	unregister_reboot_notifier(&sclp_reboot_notifier);
+fail_init_state_uninitialized:
+	sclp_init_state = sclp_init_state_uninitialized;
+fail_unlock:
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+/*
+ * SCLP panic notifier: If we are suspended, we thaw SCLP in order to be able
+ * to print the panic message.
+ */
+static int sclp_panic_notify(struct notifier_block *self,
+			     unsigned long event, void *data)
+{
+	if (sclp_suspend_state == sclp_suspend_state_suspended)
+		sclp_undo_suspend(SCLP_PM_EVENT_THAW);
+	return NOTIFY_OK;
+}
+
+static struct notifier_block sclp_on_panic_nb = {
+	.notifier_call = sclp_panic_notify,
+	.priority = SCLP_PANIC_PRIO,
+};
+
+static __init int sclp_initcall(void)
+{
+	int rc;
+
+	rc = platform_driver_register(&sclp_pdrv);
+	if (rc)
+		return rc;
+
+	sclp_pdev = platform_device_register_simple("sclp", -1, NULL, 0);
+	rc = PTR_ERR_OR_ZERO(sclp_pdev);
+	if (rc)
+		goto fail_platform_driver_unregister;
+
+	rc = atomic_notifier_chain_register(&panic_notifier_list,
+					    &sclp_on_panic_nb);
+	if (rc)
+		goto fail_platform_device_unregister;
+
+	return sclp_init();
+
+fail_platform_device_unregister:
+	platform_device_unregister(sclp_pdev);
+fail_platform_driver_unregister:
+	platform_driver_unregister(&sclp_pdrv);
+	return rc;
+}
+
+arch_initcall(sclp_initcall);