[S390] pm: power management support for SCLP drivers.

The SCLP base driver defines a new notifier call back for all upper level SCLP
drivers, like the SCLP console, etc. This guarantees that in suspend first the
upper level drivers are suspended and afterwards the SCLP base driver. For
resume it is the other way round. The SCLP base driver itself registers a
new platform device at the platform bus and gets PM notifications via
the dev_pm_ops.

In suspend, the SCLP base driver switches off the receiver and sender mask
This is done in sclp_deactivate(). After suspend all new requests will be
rejected with -EIO and no more interrupts will be received, because the masks
are switched off. For resume the sender and receiver masks are reset in
the sclp_reactivate() function.

When the SCLP console is suspended, all new messages are cached in the
sclp console buffers. In resume, all the cached messages are written to the
console. In addition to that we have an early resume function that removes
the cached messages from the suspend image.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 99 insertions, 40 deletions

diff --git a/drivers/s390/char/sclp_con.c b/drivers/s390/char/sclp_con.c
index 9a25c4bd1421..336811a77672 100644
--- a/drivers/s390/char/sclp_con.c
+++ b/drivers/s390/char/sclp_con.c
@@ -1,11 +1,9 @@
 /*
- *  drivers/s390/char/sclp_con.c
- *    SCLP line mode console driver
+ * SCLP line mode console driver
  *
- *  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>
+ * Copyright IBM Corp. 1999, 2009
+ * Author(s): Martin Peschke <mpeschke@de.ibm.com>
+ *	      Martin Schwidefsky <schwidefsky@de.ibm.com>
  */
 
 #include <linux/kmod.h>
@@ -32,13 +30,14 @@ static spinlock_t sclp_con_lock;
 static struct list_head sclp_con_pages;
 /* List of full struct sclp_buffer structures ready for output */
 static struct list_head sclp_con_outqueue;
-/* Counter how many buffers are emitted (max 1) and how many */
-/* are on the output queue. */
-static int sclp_con_buffer_count;
 /* Pointer to current console buffer */
 static struct sclp_buffer *sclp_conbuf;
 /* Timer for delayed output of console messages */
 static struct timer_list sclp_con_timer;
+/* Suspend mode flag */
+static int sclp_con_suspended;
+/* Flag that output queue is currently running */
+static int sclp_con_queue_running;
 
 /* Output format for console messages */
 static unsigned short sclp_con_columns;
@@ -53,42 +52,71 @@ sclp_conbuf_callback(struct sclp_buffer *buffer, int rc)
 	do {
 		page = sclp_unmake_buffer(buffer);
 		spin_lock_irqsave(&sclp_con_lock, flags);
+
 		/* Remove buffer from outqueue */
 		list_del(&buffer->list);
-		sclp_con_buffer_count--;
 		list_add_tail((struct list_head *) page, &sclp_con_pages);
+
 		/* Check if there is a pending buffer on the out queue. */
 		buffer = NULL;
 		if (!list_empty(&sclp_con_outqueue))
-			buffer = list_entry(sclp_con_outqueue.next,
-					    struct sclp_buffer, list);
+			buffer = list_first_entry(&sclp_con_outqueue,
+						  struct sclp_buffer, list);
+		if (!buffer || sclp_con_suspended) {
+			sclp_con_queue_running = 0;
+			spin_unlock_irqrestore(&sclp_con_lock, flags);
+			break;
+		}
 		spin_unlock_irqrestore(&sclp_con_lock, flags);
-	} while (buffer && sclp_emit_buffer(buffer, sclp_conbuf_callback));
+	} while (sclp_emit_buffer(buffer, sclp_conbuf_callback));
 }
 
-static void
-sclp_conbuf_emit(void)
+/*
+ * Finalize and emit first pending buffer.
+ */
+static void sclp_conbuf_emit(void)
 {
 	struct sclp_buffer* buffer;
 	unsigned long flags;
-	int count;
 	int rc;
 
 	spin_lock_irqsave(&sclp_con_lock, flags);
-	buffer = sclp_conbuf;
+	if (sclp_conbuf)
+		list_add_tail(&sclp_conbuf->list, &sclp_con_outqueue);
 	sclp_conbuf = NULL;
-	if (buffer == NULL) {
-		spin_unlock_irqrestore(&sclp_con_lock, flags);
-		return;
-	}
-	list_add_tail(&buffer->list, &sclp_con_outqueue);
-	count = sclp_con_buffer_count++;
+	if (sclp_con_queue_running || sclp_con_suspended)
+		goto out_unlock;
+	if (list_empty(&sclp_con_outqueue))
+		goto out_unlock;
+	buffer = list_first_entry(&sclp_con_outqueue, struct sclp_buffer,
+				  list);
+	sclp_con_queue_running = 1;
 	spin_unlock_irqrestore(&sclp_con_lock, flags);
-	if (count)
-		return;
+
 	rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
 	if (rc)
 		sclp_conbuf_callback(buffer, rc);
+	return;
+out_unlock:
+	spin_unlock_irqrestore(&sclp_con_lock, flags);
+}
+
+/*
+ * Wait until out queue is empty
+ */
+static void sclp_console_sync_queue(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sclp_con_lock, flags);
+	if (timer_pending(&sclp_con_timer))
+		del_timer_sync(&sclp_con_timer);
+	while (sclp_con_queue_running) {
+		spin_unlock_irqrestore(&sclp_con_lock, flags);
+		sclp_sync_wait();
+		spin_lock_irqsave(&sclp_con_lock, flags);
+	}
+	spin_unlock_irqrestore(&sclp_con_lock, flags);
 }
 
 /*
@@ -123,6 +151,8 @@ sclp_console_write(struct console *console, const char *message,
 		/* make sure we have a console output buffer */
 		if (sclp_conbuf == NULL) {
 			while (list_empty(&sclp_con_pages)) {
+				if (sclp_con_suspended)
+					goto out;
 				spin_unlock_irqrestore(&sclp_con_lock, flags);
 				sclp_sync_wait();
 				spin_lock_irqsave(&sclp_con_lock, flags);
@@ -157,6 +187,7 @@ sclp_console_write(struct console *console, const char *message,
 		sclp_con_timer.expires = jiffies + HZ/10;
 		add_timer(&sclp_con_timer);
 	}
+out:
 	spin_unlock_irqrestore(&sclp_con_lock, flags);
 }
 
@@ -168,30 +199,43 @@ sclp_console_device(struct console *c, int *index)
 }
 
 /*
- * This routine is called from panic when the kernel
- * is going to give up. We have to make sure that all buffers
- * will be flushed to the SCLP.
+ * Make sure that all buffers will be flushed to the SCLP.
  */
 static void
 sclp_console_flush(void)
 {
+	sclp_conbuf_emit();
+	sclp_console_sync_queue();
+}
+
+/*
+ * Resume console: If there are cached messages, emit them.
+ */
+static void sclp_console_resume(void)
+{
 	unsigned long flags;
 
+	spin_lock_irqsave(&sclp_con_lock, flags);
+	sclp_con_suspended = 0;
+	spin_unlock_irqrestore(&sclp_con_lock, flags);
 	sclp_conbuf_emit();
+}
+
+/*
+ * Suspend console: Set suspend flag and flush console
+ */
+static void sclp_console_suspend(void)
+{
+	unsigned long flags;
+
 	spin_lock_irqsave(&sclp_con_lock, flags);
-	if (timer_pending(&sclp_con_timer))
-		del_timer(&sclp_con_timer);
-	while (sclp_con_buffer_count > 0) {
-		spin_unlock_irqrestore(&sclp_con_lock, flags);
-		sclp_sync_wait();
-		spin_lock_irqsave(&sclp_con_lock, flags);
-	}
+	sclp_con_suspended = 1;
 	spin_unlock_irqrestore(&sclp_con_lock, flags);
+	sclp_console_flush();
 }
 
-static int
-sclp_console_notify(struct notifier_block *self,
-			  unsigned long event, void *data)
+static int sclp_console_notify(struct notifier_block *self,
+			       unsigned long event, void *data)
 {
 	sclp_console_flush();
 	return NOTIFY_OK;
@@ -199,7 +243,7 @@ sclp_console_notify(struct notifier_block *self,
 
 static struct notifier_block on_panic_nb = {
 	.notifier_call = sclp_console_notify,
-	.priority = 1,
+	.priority = SCLP_PANIC_PRIO_CLIENT,
 };
 
 static struct notifier_block on_reboot_nb = {
@@ -221,6 +265,22 @@ static struct console sclp_console =
 };
 
 /*
+ * This function is called for SCLP suspend and resume events.
+ */
+void sclp_console_pm_event(enum sclp_pm_event sclp_pm_event)
+{
+	switch (sclp_pm_event) {
+	case SCLP_PM_EVENT_FREEZE:
+		sclp_console_suspend();
+		break;
+	case SCLP_PM_EVENT_RESTORE:
+	case SCLP_PM_EVENT_THAW:
+		sclp_console_resume();
+		break;
+	}
+}
+
+/*
  * called by console_init() in drivers/char/tty_io.c at boot-time.
  */
 static int __init
@@ -243,7 +303,6 @@ sclp_console_init(void)
 	}
 	INIT_LIST_HEAD(&sclp_con_outqueue);
 	spin_lock_init(&sclp_con_lock);
-	sclp_con_buffer_count = 0;
 	sclp_conbuf = NULL;
 	init_timer(&sclp_con_timer);