1 files changed, 297 insertions, 0 deletions
diff --git a/drivers/s390/char/sclp_con.c b/drivers/s390/char/sclp_con.c
new file mode 100644
index 000000000..e5d947c76
--- /dev/null
+++ b/drivers/s390/char/sclp_con.c
@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCLP line mode console driver
+ *
+ * Copyright IBM Corp. 1999, 2009
+ * Author(s): Martin Peschke <mpeschke@de.ibm.com>
+ *	      Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/kmod.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/panic_notifier.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+#include <linux/termios.h>
+#include <linux/err.h>
+#include <linux/reboot.h>
+#include <linux/gfp.h>
+
+#include "sclp.h"
+#include "sclp_rw.h"
+#include "sclp_tty.h"
+
+#define sclp_console_major 4		/* TTYAUX_MAJOR */
+#define sclp_console_minor 64
+#define sclp_console_name  "ttyS"
+
+/* Lock to guard over changes to global variables */
+static DEFINE_SPINLOCK(sclp_con_lock);
+/* List of free pages that can be used for console output buffering */
+static LIST_HEAD(sclp_con_pages);
+/* List of full struct sclp_buffer structures ready for output */
+static LIST_HEAD(sclp_con_outqueue);
+/* 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;
+/* Flag that output queue is currently running */
+static int sclp_con_queue_running;
+
+/* Output format for console messages */
+#define SCLP_CON_COLUMNS	320
+#define SPACES_PER_TAB		8
+
+static void
+sclp_conbuf_callback(struct sclp_buffer *buffer, int rc)
+{
+	unsigned long flags;
+	void *page;
+
+	do {
+		page = sclp_unmake_buffer(buffer);
+		spin_lock_irqsave(&sclp_con_lock, flags);
+
+		/* Remove buffer from outqueue */
+		list_del(&buffer->list);
+		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_first_entry(&sclp_con_outqueue,
+						  struct sclp_buffer, list);
+		if (!buffer) {
+			sclp_con_queue_running = 0;
+			spin_unlock_irqrestore(&sclp_con_lock, flags);
+			break;
+		}
+		spin_unlock_irqrestore(&sclp_con_lock, flags);
+	} while (sclp_emit_buffer(buffer, sclp_conbuf_callback));
+}
+
+/*
+ * Finalize and emit first pending buffer.
+ */
+static void sclp_conbuf_emit(void)
+{
+	struct sclp_buffer* buffer;
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(&sclp_con_lock, flags);
+	if (sclp_conbuf)
+		list_add_tail(&sclp_conbuf->list, &sclp_con_outqueue);
+	sclp_conbuf = NULL;
+	if (sclp_con_queue_running)
+		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);
+
+	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);
+	del_timer(&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);
+}
+
+/*
+ * When this routine is called from the timer then we flush the
+ * temporary write buffer without further waiting on a final new line.
+ */
+static void
+sclp_console_timeout(struct timer_list *unused)
+{
+	sclp_conbuf_emit();
+}
+
+/*
+ * Drop oldest console buffer if sclp_con_drop is set
+ */
+static int
+sclp_console_drop_buffer(void)
+{
+	struct list_head *list;
+	struct sclp_buffer *buffer;
+	void *page;
+
+	if (!sclp_console_drop)
+		return 0;
+	list = sclp_con_outqueue.next;
+	if (sclp_con_queue_running)
+		/* The first element is in I/O */
+		list = list->next;
+	if (list == &sclp_con_outqueue)
+		return 0;
+	list_del(list);
+	buffer = list_entry(list, struct sclp_buffer, list);
+	page = sclp_unmake_buffer(buffer);
+	list_add_tail((struct list_head *) page, &sclp_con_pages);
+	return 1;
+}
+
+/*
+ * Writes the given message to S390 system console
+ */
+static void
+sclp_console_write(struct console *console, const char *message,
+		   unsigned int count)
+{
+	unsigned long flags;
+	void *page;
+	int written;
+
+	if (count == 0)
+		return;
+	spin_lock_irqsave(&sclp_con_lock, flags);
+	/*
+	 * process escape characters, write message into buffer,
+	 * send buffer to SCLP
+	 */
+	do {
+		/* make sure we have a console output buffer */
+		if (sclp_conbuf == NULL) {
+			if (list_empty(&sclp_con_pages))
+				sclp_console_full++;
+			while (list_empty(&sclp_con_pages)) {
+				if (sclp_console_drop_buffer())
+					break;
+				spin_unlock_irqrestore(&sclp_con_lock, flags);
+				sclp_sync_wait();
+				spin_lock_irqsave(&sclp_con_lock, flags);
+			}
+			page = sclp_con_pages.next;
+			list_del((struct list_head *) page);
+			sclp_conbuf = sclp_make_buffer(page, SCLP_CON_COLUMNS,
+						       SPACES_PER_TAB);
+		}
+		/* try to write the string to the current output buffer */
+		written = sclp_write(sclp_conbuf, (const unsigned char *)
+				     message, count);
+		if (written == count)
+			break;
+		/*
+		 * Not all characters could be written to the current
+		 * output buffer. Emit the buffer, create a new buffer
+		 * and then output the rest of the string.
+		 */
+		spin_unlock_irqrestore(&sclp_con_lock, flags);
+		sclp_conbuf_emit();
+		spin_lock_irqsave(&sclp_con_lock, flags);
+		message += written;
+		count -= written;
+	} while (count > 0);
+	/* Setup timer to output current console buffer after 1/10 second */
+	if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
+	    !timer_pending(&sclp_con_timer)) {
+		mod_timer(&sclp_con_timer, jiffies + HZ / 10);
+	}
+	spin_unlock_irqrestore(&sclp_con_lock, flags);
+}
+
+static struct tty_driver *
+sclp_console_device(struct console *c, int *index)
+{
+	*index = c->index;
+	return sclp_tty_driver;
+}
+
+/*
+ * This panic/reboot notifier makes sure that all buffers
+ * will be flushed to the SCLP.
+ */
+static int sclp_console_notify(struct notifier_block *self,
+			       unsigned long event, void *data)
+{
+	/*
+	 * Perform the lock check before effectively getting the
+	 * lock on sclp_conbuf_emit() / sclp_console_sync_queue()
+	 * to prevent potential lockups in atomic context.
+	 */
+	if (spin_is_locked(&sclp_con_lock))
+		return NOTIFY_DONE;
+
+	sclp_conbuf_emit();
+	sclp_console_sync_queue();
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block on_panic_nb = {
+	.notifier_call = sclp_console_notify,
+	.priority = INT_MIN + 1, /* run the callback late */
+};
+
+static struct notifier_block on_reboot_nb = {
+	.notifier_call = sclp_console_notify,
+	.priority = INT_MIN + 1, /* run the callback late */
+};
+
+/*
+ * used to register the SCLP console to the kernel and to
+ * give printk necessary information
+ */
+static struct console sclp_console =
+{
+	.name = sclp_console_name,
+	.write = sclp_console_write,
+	.device = sclp_console_device,
+	.flags = CON_PRINTBUFFER,
+	.index = 0 /* ttyS0 */
+};
+
+/*
+ * called by console_init() in drivers/char/tty_io.c at boot-time.
+ */
+static int __init
+sclp_console_init(void)
+{
+	void *page;
+	int i;
+	int rc;
+
+	/* SCLP consoles are handled together */
+	if (!(CONSOLE_IS_SCLP || CONSOLE_IS_VT220))
+		return 0;
+	rc = sclp_rw_init();
+	if (rc)
+		return rc;
+	/* Allocate pages for output buffering */
+	for (i = 0; i < sclp_console_pages; i++) {
+		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+		list_add_tail(page, &sclp_con_pages);
+	}
+	sclp_conbuf = NULL;
+	timer_setup(&sclp_con_timer, sclp_console_timeout, 0);
+
+	/* enable printk-access to this driver */
+	atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
+	register_reboot_notifier(&on_reboot_nb);
+	register_console(&sclp_console);
+	return 0;
+}
+
+console_initcall(sclp_console_init);