Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1315 insertions, 0 deletions

diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
new file mode 100644
index 0000000000..8f74db689a
--- /dev/null
+++ b/drivers/s390/char/sclp.c
@@ -0,0 +1,1315 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/panic_notifier.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/platform_device.h>
+#include <asm/types.h>
+#include <asm/irq.h>
+#include <asm/debug.h>
+
+#include "sclp.h"
+
+#define SCLP_HEADER		"sclp: "
+
+struct sclp_trace_entry {
+	char id[4] __nonstring;
+	u32 a;
+	u64 b;
+};
+
+#define SCLP_TRACE_ENTRY_SIZE		sizeof(struct sclp_trace_entry)
+#define SCLP_TRACE_MAX_SIZE		128
+#define SCLP_TRACE_EVENT_MAX_SIZE	64
+
+/* Debug trace area intended for all entries in abbreviated form. */
+DEFINE_STATIC_DEBUG_INFO(sclp_debug, "sclp", 8, 1, SCLP_TRACE_ENTRY_SIZE,
+			 &debug_hex_ascii_view);
+
+/* Error trace area intended for full entries relating to failed requests. */
+DEFINE_STATIC_DEBUG_INFO(sclp_debug_err, "sclp_err", 4, 1,
+			 SCLP_TRACE_ENTRY_SIZE, &debug_hex_ascii_view);
+
+/* 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 LIST_HEAD(sclp_reg_list);
+
+/* List of queued requests. */
+static LIST_HEAD(sclp_req_queue);
+
+/* Data for read and init requests. */
+static struct sclp_req sclp_read_req;
+static struct sclp_req sclp_init_req;
+static void *sclp_read_sccb;
+static struct init_sccb *sclp_init_sccb;
+
+/* 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 */
+bool sclp_console_drop = true;
+/* Number of times the console dropped buffer pages */
+unsigned long sclp_console_full;
+
+/* The currently active SCLP command word. */
+static sclp_cmdw_t active_cmd;
+
+static inline void sclp_trace(int prio, char *id, u32 a, u64 b, bool err)
+{
+	struct sclp_trace_entry e;
+
+	memset(&e, 0, sizeof(e));
+	strncpy(e.id, id, sizeof(e.id));
+	e.a = a;
+	e.b = b;
+	debug_event(&sclp_debug, prio, &e, sizeof(e));
+	if (err)
+		debug_event(&sclp_debug_err, 0, &e, sizeof(e));
+}
+
+static inline int no_zeroes_len(void *data, int len)
+{
+	char *d = data;
+
+	/* Minimize trace area usage by not tracing trailing zeroes. */
+	while (len > SCLP_TRACE_ENTRY_SIZE && d[len - 1] == 0)
+		len--;
+
+	return len;
+}
+
+static inline void sclp_trace_bin(int prio, void *d, int len, int errlen)
+{
+	debug_event(&sclp_debug, prio, d, no_zeroes_len(d, len));
+	if (errlen)
+		debug_event(&sclp_debug_err, 0, d, no_zeroes_len(d, errlen));
+}
+
+static inline int abbrev_len(sclp_cmdw_t cmd, struct sccb_header *sccb)
+{
+	struct evbuf_header *evbuf = (struct evbuf_header *)(sccb + 1);
+	int len = sccb->length, limit = SCLP_TRACE_MAX_SIZE;
+
+	/* Full SCCB tracing if debug level is set to max. */
+	if (sclp_debug.level == DEBUG_MAX_LEVEL)
+		return len;
+
+	/* Minimal tracing for console writes. */
+	if (cmd == SCLP_CMDW_WRITE_EVENT_DATA &&
+	    (evbuf->type == EVTYP_MSG  || evbuf->type == EVTYP_VT220MSG))
+		limit = SCLP_TRACE_ENTRY_SIZE;
+
+	return min(len, limit);
+}
+
+static inline void sclp_trace_sccb(int prio, char *id, u32 a, u64 b,
+				   sclp_cmdw_t cmd, struct sccb_header *sccb,
+				   bool err)
+{
+	sclp_trace(prio, id, a, b, err);
+	if (sccb) {
+		sclp_trace_bin(prio + 1, sccb, abbrev_len(cmd, sccb),
+			       err ? sccb->length : 0);
+	}
+}
+
+static inline void sclp_trace_evbuf(int prio, char *id, u32 a, u64 b,
+				    struct evbuf_header *evbuf, bool err)
+{
+	sclp_trace(prio, id, a, b, err);
+	sclp_trace_bin(prio + 1, evbuf,
+		       min((int)evbuf->length, (int)SCLP_TRACE_EVENT_MAX_SIZE),
+		       err ? evbuf->length : 0);
+}
+
+static inline void sclp_trace_req(int prio, char *id, struct sclp_req *req,
+				  bool err)
+{
+	struct sccb_header *sccb = req->sccb;
+	union {
+		struct {
+			u16 status;
+			u16 response;
+			u16 timeout;
+			u16 start_count;
+		};
+		u64 b;
+	} summary;
+
+	summary.status = req->status;
+	summary.response = sccb ? sccb->response_code : 0;
+	summary.timeout = (u16)req->queue_timeout;
+	summary.start_count = (u16)req->start_count;
+
+	sclp_trace(prio, id, __pa(sccb), summary.b, err);
+}
+
+static inline void sclp_trace_register(int prio, char *id, u32 a, u64 b,
+				       struct sclp_register *reg)
+{
+	struct {
+		u64 receive;
+		u64 send;
+	} d;
+
+	d.receive = reg->receive_mask;
+	d.send = reg->send_mask;
+
+	sclp_trace(prio, id, a, b, false);
+	sclp_trace_bin(prio, &d, sizeof(d), 0);
+}
+
+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)
+{
+	return kstrtobool(str, &sclp_console_drop) == 0;
+}
+
+__setup("sclp_con_drop=", sclp_setup_console_drop);
+
+/* 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 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;
+
+/* 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_request_timeout(bool force_restart);
+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);
+
+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 (*cb)(struct timer_list *))
+{
+	del_timer(&sclp_request_timer);
+	sclp_request_timer.function = cb;
+	sclp_request_timer.expires = jiffies + time;
+	add_timer(&sclp_request_timer);
+}
+
+static void sclp_request_timeout_restart(struct timer_list *unused)
+{
+	sclp_request_timeout(true);
+}
+
+static void sclp_request_timeout_normal(struct timer_list *unused)
+{
+	sclp_request_timeout(false);
+}
+
+/* Request timeout handler. Restart the request queue. If force_restart,
+ * force restart of running request. */
+static void sclp_request_timeout(bool force_restart)
+{
+	unsigned long flags;
+
+	/* TMO: A timeout occurred (a=force_restart) */
+	sclp_trace(2, "TMO", force_restart, 0, true);
+
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (force_restart) {
+		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_normal);
+	}
+	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(struct timer_list *unused)
+{
+	unsigned long flags, expires_next;
+	struct sclp_req *req;
+
+	do {
+		req = __sclp_req_queue_remove_expired_req();
+
+		if (req) {
+			/* RQTM: Request timed out (a=sccb, b=summary) */
+			sclp_trace_req(2, "RQTM", req, true);
+		}
+
+		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);
+}
+
+static int sclp_service_call_trace(sclp_cmdw_t command, void *sccb)
+{
+	static u64 srvc_count;
+	int rc;
+
+	/* SRV1: Service call about to be issued (a=command, b=sccb address) */
+	sclp_trace_sccb(0, "SRV1", command, (u64)sccb, command, sccb, false);
+
+	rc = sclp_service_call(command, sccb);
+
+	/* SRV2: Service call was issued (a=rc, b=SRVC sequence number) */
+	sclp_trace(0, "SRV2", -rc, ++srvc_count, rc != 0);
+
+	if (rc == 0)
+		active_cmd = command;
+
+	return rc;
+}
+
+/* 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_trace(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_restart);
+		return 0;
+	} else if (rc == -EBUSY) {
+		/* Try again later */
+		__sclp_set_request_timer(SCLP_BUSY_INTERVAL * HZ,
+					 sclp_request_timeout_normal);
+		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);
+		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_normal);
+			break;
+		}
+		/* Post-processing for aborted request */
+		list_del(&req->list);
+
+		/* RQAB: Request aborted (a=sccb, b=summary) */
+		sclp_trace_req(2, "RQAB", req, true);
+
+		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_init_req)
+		return 1;
+	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;
+	}
+
+	/* RQAD: Request was added (a=sccb, b=caller) */
+	sclp_trace(2, "RQAD", __pa(req->sccb), _RET_IP_, false);
+
+	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) {
+		rc = __sclp_start_request(req);
+		if (rc)
+			list_del(&req->list);
+	}
+	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 & SCLP_EVTYP_MASK(evbuf->type))
+				break;
+			else
+				reg = NULL;
+		}
+
+		/* EVNT: Event callback (b=receiver) */
+		sclp_trace_evbuf(2, "EVNT", 0, reg ? (u64)reg->receiver_fn : 0,
+				 evbuf, !reg);
+
+		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 == __pa(req->sccb))
+			return req;
+	}
+	return NULL;
+}
+
+static bool ok_response(u32 sccb_int, sclp_cmdw_t cmd)
+{
+	struct sccb_header *sccb = (struct sccb_header *)__va(sccb_int);
+	struct evbuf_header *evbuf;
+	u16 response;
+
+	if (!sccb)
+		return true;
+
+	/* Check SCCB response. */
+	response = sccb->response_code & 0xff;
+	if (response != 0x10 && response != 0x20)
+		return false;
+
+	/* Check event-processed flag on outgoing events. */
+	if (cmd == SCLP_CMDW_WRITE_EVENT_DATA) {
+		evbuf = (struct evbuf_header *)(sccb + 1);
+		if (!(evbuf->flags & 0x80))
+			return false;
+	}
+
+	return true;
+}
+
+/* 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;
+
+	/* INT: Interrupt received (a=intparm, b=cmd) */
+	sclp_trace_sccb(0, "INT", param32, active_cmd, active_cmd,
+			(struct sccb_header *)__va(finished_sccb),
+			!ok_response(finished_sccb, active_cmd));
+
+	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;
+
+			/* RQOK: Request success (a=sccb, b=summary) */
+			sclp_trace_req(2, "RQOK", req, false);
+
+			if (req->callback) {
+				spin_unlock(&sclp_lock);
+				req->callback(req, req->callback_data);
+				spin_lock(&sclp_lock);
+			}
+		} else {
+			/* UNEX: Unexpected SCCB completion (a=sccb address) */
+			sclp_trace(0, "UNEX", finished_sccb, 0, true);
+		}
+		sclp_running_state = sclp_running_state_idle;
+		active_cmd = 0;
+	}
+	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;
+	static u64 sync_count;
+	u64 timeout;
+	int irq_context;
+
+	/* SYN1: Synchronous wait start (a=runstate, b=sync count) */
+	sclp_trace(4, "SYN1", sclp_running_state, ++sync_count, false);
+
+	/* 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_IRQ_SUBCLASS_MASK;
+	cr0_sync |= 1UL << (63 - 54);
+	__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 (get_tod_clock_fast() > timeout && del_timer(&sclp_request_timer))
+			sclp_request_timer.function(&sclp_request_timer);
+		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);
+
+	/* SYN2: Synchronous wait end (a=runstate, b=sync_count) */
+	sclp_trace(4, "SYN2", sclp_running_state, sync_count, false);
+}
+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) {
+			/* STCG: State-change callback (b=callback) */
+			sclp_trace(2, "STCG", 0, (u64)reg->state_change_fn,
+				   false);
+
+			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;
+	u8		masks[2 * 1021 + 4];	/* variable length */
+	/*
+	 * u8		sclp_receive_mask[mask_length];
+	 * u8		sclp_send_mask[mask_length];
+	 * 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;
+
+	BUILD_BUG_ON(sizeof(struct sclp_statechangebuf) > PAGE_SIZE);
+
+	scbuf = (struct sclp_statechangebuf *) evbuf;
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (scbuf->validity_sclp_receive_mask)
+		sclp_receive_mask = sccb_get_recv_mask(scbuf);
+	if (scbuf->validity_sclp_send_mask)
+		sclp_send_mask = sccb_get_send_mask(scbuf);
+	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;
+
+	/* REG: Event listener registered (b=caller) */
+	sclp_trace_register(2, "REG", 0, _RET_IP_, reg);
+
+	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;
+	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;
+
+	/* UREG: Event listener unregistered (b=caller) */
+	sclp_trace_register(2, "UREG", 0, _RET_IP_, reg);
+
+	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(sccb_mask_t receive_mask, sccb_mask_t send_mask)
+{
+	struct init_sccb *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(*sccb);
+	if (sclp_mask_compat_mode)
+		sccb->mask_length = SCLP_MASK_SIZE_COMPAT;
+	else
+		sccb->mask_length = sizeof(sccb_mask_t);
+	sccb_set_recv_mask(sccb, receive_mask);
+	sccb_set_send_mask(sccb, send_mask);
+	sccb_set_sclp_recv_mask(sccb, 0);
+	sccb_set_sclp_send_mask(sccb, 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 = 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_get_sclp_recv_mask(sccb);
+				sclp_send_mask = sccb_get_sclp_send_mask(sccb);
+			} 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 != __pa(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(struct timer_list *unused)
+{
+	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_trace(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);
+		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);
+		rc = -EBUSY;
+		if (sclp_init_req.status == SCLP_REQ_DONE) {
+			if (sccb->header.response_code == 0x20) {
+				rc = 0;
+				break;
+			} else if (sccb->header.response_code == 0x74f0) {
+				if (!sclp_mask_compat_mode) {
+					sclp_mask_compat_mode = true;
+					retry = 0;
+				}
+			}
+		}
+	}
+	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
+};
+
+static ssize_t con_pages_show(struct device_driver *dev, char *buf)
+{
+	return sysfs_emit(buf, "%i\n", sclp_console_pages);
+}
+
+static DRIVER_ATTR_RO(con_pages);
+
+static ssize_t con_drop_store(struct device_driver *dev, const char *buf, size_t count)
+{
+	int rc;
+
+	rc = kstrtobool(buf, &sclp_console_drop);
+	return rc ?: count;
+}
+
+static ssize_t con_drop_show(struct device_driver *dev, char *buf)
+{
+	return sysfs_emit(buf, "%i\n", sclp_console_drop);
+}
+
+static DRIVER_ATTR_RW(con_drop);
+
+static ssize_t con_full_show(struct device_driver *dev, char *buf)
+{
+	return sysfs_emit(buf, "%lu\n", sclp_console_full);
+}
+
+static DRIVER_ATTR_RO(con_full);
+
+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",
+		.groups = sclp_drv_attr_groups,
+	},
+};
+
+/* 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;
+	sclp_read_sccb = (void *) __get_free_page(GFP_ATOMIC | GFP_DMA);
+	sclp_init_sccb = (void *) __get_free_page(GFP_ATOMIC | GFP_DMA);
+	BUG_ON(!sclp_read_sccb || !sclp_init_sccb);
+	/* Set up variables */
+	list_add(&sclp_state_change_event.list, &sclp_reg_list);
+	timer_setup(&sclp_request_timer, NULL, 0);
+	timer_setup(&sclp_queue_timer, sclp_req_queue_timeout, 0);
+	/* 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;
+	free_page((unsigned long) sclp_read_sccb);
+	free_page((unsigned long) sclp_init_sccb);
+fail_unlock:
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	return rc;
+}
+
+static __init int sclp_initcall(void)
+{
+	int rc;
+
+	rc = platform_driver_register(&sclp_pdrv);
+	if (rc)
+		return rc;
+
+	return sclp_init();
+}
+
+arch_initcall(sclp_initcall);