Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 915 insertions, 0 deletions

diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
new file mode 100644
index 0000000..ceb0e47
--- /dev/null
+++ b/drivers/s390/char/sclp.c
@@ -0,0 +1,915 @@
+/*
+ *  drivers/s390/char/sclp.c
+ *     core function to access sclp interface
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *    Author(s): Martin Peschke <mpeschke@de.ibm.com>
+ *		 Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#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 <asm/types.h>
+#include <asm/s390_ext.h>
+
+#include "sclp.h"
+
+#define SCLP_HEADER		"sclp: "
+
+/* Structure for register_early_external_interrupt. */
+static ext_int_info_t ext_int_info_hwc;
+
+/* Lock to protect internal data consistency. */
+static DEFINE_SPINLOCK(sclp_lock);
+
+/* Mask of events that we can receive from the sclp interface. */
+static sccb_mask_t sclp_receive_mask;
+
+/* Mask of events that we can send to 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)));
+
+/* Timer for request retries. */
+static struct timer_list sclp_request_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 = 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
+#define SCLP_REQUEST_RETRY	3
+
+/* Timeout intervals in seconds.*/
+#define SCLP_BUSY_INTERVAL	2
+#define SCLP_RETRY_INTERVAL	5
+
+static void sclp_process_queue(void);
+static int sclp_init_mask(int calculate);
+static int sclp_init(void);
+
+/* Perform service call. Return 0 on success, non-zero otherwise. */
+static int
+service_call(sclp_cmdw_t command, void *sccb)
+{
+	int cc;
+
+	__asm__ __volatile__(
+		"   .insn rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
+		"   ipm	  %0\n"
+		"   srl	  %0,28"
+		: "=&d" (cc)
+		: "d" (command), "a" (__pa(sccb))
+		: "cc", "memory" );
+	if (cc == 3)
+		return -EIO;
+	if (cc == 2)
+		return -EBUSY;
+	return 0;
+}
+
+/* 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;
+
+	if (data) {
+		spin_lock_irqsave(&sclp_lock, flags);
+		sclp_running_state = sclp_running_state_idle;
+		spin_unlock_irqrestore(&sclp_lock, flags);
+	}
+	sclp_process_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);
+}
+
+/* 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);
+	if (req->start_count <= SCLP_REQUEST_RETRY) {
+		rc = service_call(req->command, req->sccb);
+		req->start_count++;
+	} else
+		rc = -EIO;
+	if (rc == 0) {
+		/* Sucessfully 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);
+		rc = __sclp_start_request(req);
+		if (rc == 0)
+			break;
+		/* Request failed. */
+		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);
+}
+
+/* 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_init_state != sclp_init_state_initialized ||
+	     sclp_activation_state != sclp_activation_state_active) &&
+	    req != &sclp_init_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;
+	/* Start if request is first in list */
+	if (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) {
+		/* Search for event handler */
+		evbuf = (struct evbuf_header *) ((addr_t) sccb + offset);
+		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 = -ENOSYS;
+	}
+	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 inline 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_READDATA;
+	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 pt_regs *regs, __u16 code)
+{
+	struct sclp_req *req;
+	u32 finished_sccb;
+	u32 evbuf_pending;
+
+	spin_lock(&sclp_lock);
+	finished_sccb = S390_lowcore.ext_params & 0xfffffff8;
+	evbuf_pending = S390_lowcore.ext_params & 0x3;
+	if (finished_sccb) {
+		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_receive_mask != 0 &&
+	    sclp_reading_state == sclp_reading_state_idle &&
+	    sclp_activation_state == sclp_activation_state_active ) {
+		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);
+	}
+	spin_unlock(&sclp_lock);
+	sclp_process_queue();
+}
+
+/* Return current Time-Of-Day clock. */
+static inline u64
+sclp_get_clock(void)
+{
+	u64 result;
+
+	asm volatile ("STCK 0(%1)" : "=m" (result) : "a" (&(result)) : "cc");
+	return result;
+}
+
+/* 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 psw_mask;
+	unsigned long cr0, cr0_sync;
+	u64 timeout;
+
+	/* 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 = sclp_get_clock() +
+			  sclp_tod_from_jiffies(sclp_request_timer.expires -
+						jiffies);
+	}
+	/* Prevent bottom half from executing once we force interrupts open */
+	local_bh_disable();
+	/* Enable service-signal interruption, disable timer interrupts */
+	__ctl_store(cr0, 0, 0);
+	cr0_sync = cr0;
+	cr0_sync |= 0x00000200;
+	cr0_sync &= 0xFFFFF3AC;
+	__ctl_load(cr0_sync, 0, 0);
+	asm volatile ("STOSM 0(%1),0x01"
+		      : "=m" (psw_mask) : "a" (&psw_mask) : "memory");
+	/* 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) &&
+		    sclp_get_clock() > timeout &&
+		    del_timer(&sclp_request_timer))
+			sclp_request_timer.function(sclp_request_timer.data);
+		barrier();
+		cpu_relax();
+	}
+	/* Restore interrupt settings */
+	asm volatile ("SSM 0(%0)"
+		      : : "a" (&psw_mask) : "memory");
+	__ctl_load(cr0, 0, 0);
+	__local_bh_enable();
+}
+
+EXPORT_SYMBOL(sclp_sync_wait);
+
+/* Dispatch changes in send and receive mask to registered listeners. */
+static inline 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->receive_mask & sclp_receive_mask;
+			send_mask = reg->send_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);
+	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;
+	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);
+
+struct init_sccb {
+	struct sccb_header header;
+	u16 _reserved;
+	u16 mask_length;
+	sccb_mask_t receive_mask;
+	sccb_mask_t send_mask;
+	sccb_mask_t sclp_send_mask;
+	sccb_mask_t sclp_receive_mask;
+} __attribute__((packed));
+
+/* 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_WRITEMASK;
+	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 pt_regs *regs, __u16 code)
+{
+	u32 finished_sccb;
+
+	finished_sccb = S390_lowcore.ext_params & 0xfffffff8;
+	/* Is this the interrupt we are waiting for? */
+	if (finished_sccb == 0)
+		return;
+	if (finished_sccb != (u32) (addr_t) sclp_init_sccb) {
+		printk(KERN_WARNING SCLP_HEADER "unsolicited interrupt "
+		       "for buffer at 0x%x\n", finished_sccb);
+		return;
+	}
+	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_early_external_interrupt(0x2401, sclp_check_handler,
+					       &ext_int_info_hwc);
+	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 = 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. */
+		ctl_set_bit(0, 9);
+		/* Wait for signal from interrupt or timeout */
+		sclp_sync_wait();
+		/* Disable service-signal interruption - needs to happen
+		 * with IRQs enabled. */
+		ctl_clear_bit(0,9);
+		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_early_external_interrupt(0x2401, sclp_check_handler,
+					    &ext_int_info_hwc);
+	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
+};
+
+/* Initialize SCLP driver. Return zero if driver is operational, non-zero
+ * otherwise. */
+static int
+sclp_init(void)
+{
+	unsigned long flags;
+	int rc;
+
+	if (!MACHINE_HAS_SCLP)
+		return -ENODEV;
+	spin_lock_irqsave(&sclp_lock, flags);
+	/* Check for previous or running initialization */
+	if (sclp_init_state != sclp_init_state_uninitialized) {
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return 0;
+	}
+	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);
+	/* Check interface */
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	rc = sclp_check_interface();
+	spin_lock_irqsave(&sclp_lock, flags);
+	if (rc) {
+		sclp_init_state = sclp_init_state_uninitialized;
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return rc;
+	}
+	/* Register reboot handler */
+	rc = register_reboot_notifier(&sclp_reboot_notifier);
+	if (rc) {
+		sclp_init_state = sclp_init_state_uninitialized;
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return rc;
+	}
+	/* Register interrupt handler */
+	rc = register_early_external_interrupt(0x2401, sclp_interrupt_handler,
+					       &ext_int_info_hwc);
+	if (rc) {
+		unregister_reboot_notifier(&sclp_reboot_notifier);
+		sclp_init_state = sclp_init_state_uninitialized;
+		spin_unlock_irqrestore(&sclp_lock, flags);
+		return rc;
+	}
+	sclp_init_state = sclp_init_state_initialized;
+	spin_unlock_irqrestore(&sclp_lock, flags);
+	/* Enable service-signal external interruption - needs to happen with
+	 * IRQs enabled. */
+	ctl_set_bit(0, 9);
+	sclp_init_mask(1);
+	return 0;
+}